JPH1191989A - Sheet material conveying device and image recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To convey a sheet material according to the conveying condition of a sheet material in a curved path by detecting the moving speed of a sheet material by a detecting means to a designated driving speed by a conveying means, and switching the driving speed of the conveying means after detection. SOLUTION: In a cut sheet conveying mode, a pick-up roller 33a or 33b in an automatic paper feed unit 30 is rotated to convey a recording sheet positioned by bringing the sheet into contact with a nip part between the stopped conveying roller 10 and a pinch roller 11. Driving pulses of a conveying motor the moment the leading end of the recording sheet turns on a sheet detecting sensor are counted, and when the pulse number is smaller than a preset value, it is judged that an ordinary cut sheet is conveyed, so that the conveying speed is not changed. On the contrary, if larger, it is judged that slip is caused between the conveying roller 10 and the conveyed recording sheet by conveyance, and the thick paper conveying condition is decided, so the speed is decreased to increase the torque of the conveying motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying apparatus for conveying a sheet, and is applied to, for example, an image recording apparatus such as a copying machine, a printer, or a facsimile machine.

[0002]

2. Description of the Related Art Conventionally, as this type of image recording apparatus, for example, there are a copying machine, a printer, a facsimile machine and the like.

A copying machine generally has a function of reading an image of an original or the like and records an image on a sheet based on the read image information. Some copiers have a function of inputting image information to be sent.

[0004] A printer is generally an external device,
For example, an image is recorded on a sheet based on image information sent from an apparatus such as a computer, and a facsimile apparatus generally has a function of reading an image of a document,
Further, it has a communication function, sends read image information to the outside, and records an image on a sheet based on information sent from the outside.

[0005] These image recording apparatuses are provided with, for example, a sheet material conveying device for sending a sheet material to an image recording unit.

Some sheet conveying apparatuses can use a single sheet such as a postcard, an envelope, or a cut sheet, and a continuous sheet such as a fanfold sheet, and selectively convey each sheet. It is a configuration that can be performed.

In such an apparatus, each sheet is usually conveyed by applying a conveying force by the frictional force of the surface of a single-sheet sheet by rotating the conveying roller, and upstream of the conveying roller by a continuous sheet. This is performed by applying a transfer force by a push tractor arranged on the side.

Hereinafter, a conventional sheet conveying apparatus will be described in more detail with reference to FIGS.

FIG. 12 is an explanatory sectional view showing the structure of a sheet conveying apparatus according to the prior art when a cut sheet is selected, and FIG. 13 is an explanatory view according to the prior art when a continuous sheet is selected. FIG. 2 is an explanatory cross-sectional configuration diagram illustrating a configuration of a sheet material conveying device.

First, a case where a cut sheet is selected will be described with reference to FIG.

When a release lever (not shown) is set to the cut sheet selection position, the pinch roller 111 held by the pinch roller holder 105 is moved by the urging force of the pinch roller control spring 108 and the auxiliary roller 116 is turned on.
Is pressed against the long conveying roller 110 by the urging force of the auxiliary roller spring 109.

At the same time, the needle roller 112 held by the needle roller holder 117 is
The urging force of 18 causes the roller to be pressed against the transport roller 110.

At this time, the needle roller spring 118
The fulcrum 118 is pushed by the protrusion 127c of the release shaft 127.
The fulcrum 118a is bent around the center a, and a biasing force is generated by a spring elastic force around the fulcrum 118a.

The pinch roller 111 and the auxiliary roller 11
6, and by the urging force of the needle roller 112,
The cut sheet is placed on the platen 12 while maintaining the sheet conveyance path.
4 is transported to the recording section at a constant transport speed.

Next, a case where a continuous sheet is selected will be described with reference to FIG.

When a release lever (not shown) is set to the continuous sheet selection position, the gear of the release shaft 127 fitted with the gear of the release lever rotates.

By the rotation of the release shaft 127, FIG.
As shown in FIG. 3, the protrusion 127b is
5, the pinch roller 111 is separated from the conveying roller 110, and is retracted from the sheet conveying path.

At this time, the auxiliary roller 116 held on the rotation fulcrum 105a side of the pinch roller holder 105 also tries to move in the direction away from the transport roller 110, but the auxiliary roller spring 109 moves to the transport roller 110. To a degree that weakens the biasing force of

Further, by the rotation of the release shaft 127, the pressing of the projection 127c against the needle roller spring 118 is released, and the pressing force of the needle roller 112 against the transport roller 110 is reduced.

Therefore, when the release lever is set to the continuous sheet selection position, only the pinch roller 111 is separated from the conveyance roller 110, and the auxiliary roller 116 and the needle roller 112 are pressed against the conveyance roller 110 with a small force.

Here, the reason why the pressing force of the auxiliary roller 116 against the transport roller 110 is set to a low pressure is that the auxiliary roller 1
This is to reduce a detection error caused by the sheet detection sensor 104 disposed near the position 16.

That is, the sheet material conveyed by the conveyance roller 110 is wound around the conveyance roller 110 and conveyed due to its weight (expressed in terms of basis weight, continuous weight, etc.) or stiffness due to the type. There is a case (a sheet with a low waist) and a case where the sheet is conveyed along the roller facing portion 106a of the paper pan 106 (a sheet with a high waist).

For this reason, if the pressing force of the auxiliary roller 116 is “0”, the weight or the stiffness of the sheet causes
The auxiliary roller 116 is separated from the peripheral surface of the transport roller 110.

That is, by pressing the auxiliary roller 116 against the conveying roller 110 with an appropriate pressing force, the sheet conveyed in the vicinity of the sheet detection sensor 104 is always conveyed while being wound around the conveying roller 110. Therefore, the above-described detection error can be reduced.

In this way, the continuous sheet is conveyed at a constant conveying speed to the recording section on the platen 124 mainly by the conveying force of the tractor 103.

The cut sheet or the continuous sheet conveyed to the recording unit is printed by a recording head (not shown) and is discharged by a discharge roller 114.

[0027]

However, in the case of the above-described prior art, the following problems have occurred.

In the above-described conventional sheet conveying apparatus, the conveying speed of the conveying roller 110 is set to a high speed in order to increase the processing speed. Since the transport path is formed in a U-turn so that the paper ports are substantially parallel, there are the following problems when transporting thick paper such as postcards and envelopes.

In order to transport stiff paper such as postcards and envelopes in a U-turn shape, the pinch roller 111 and the auxiliary roller 1 are used.
16, and it is necessary to increase the urging force of the needle roller 112 to some extent, but this increases the load for rotating the transport roller 110, and in some cases,
In some cases, the stepping motor driving the transport roller 110 lacks torque and loses synchronism.

Here, there is a method of reducing the transport speed in order to prevent the stepping motor that drives the transport roller 110 from stepping out. However, if this method is performed, the cut paper having no problem in the torque of the motor can be obtained. Also in the case of (1), the transport speed is reduced, and the adverse effect of reducing the processing speed occurs.

It is conceivable to provide two types of transport speeds of the transport roller 110, a high speed for cut paper and a low speed for thick paper. In this case, the user must set the transport speed for each paper type. The disadvantage is that the workability is reduced.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to enable stable sheet conveyance at an appropriate conveyance speed according to the type of sheet material to be conveyed. The object of the present invention is to provide a sheet conveying apparatus and an image recording apparatus having excellent reliability.

[0033]

In order to achieve the above object, according to the present invention, there is provided a sheet conveying path having a bent path, and conveying means for conveying the sheet along the sheet conveying path. And a detecting means for detecting a moving speed of the sheet material with respect to a predetermined driving speed by the conveying means at a predetermined position in the bending path, and detecting the moving speed of the sheet material based on a detection result of the detecting means. The present invention is characterized in that switching control of a driving speed of a later conveying means is performed.

Accordingly, by detecting the moving speed of the sheet material by the detecting means with respect to the predetermined driving speed by the conveying means and switching the driving speed of the conveying means after the detection, the conveying state of the sheet material in the bent path is changed. Can be transported according to the conditions.

The detecting means may detect a moving speed of the conveyed sheet material based on a conveying force applied by the conveying means in the vicinity of the most upstream portion of the bending path.

If the detecting means detects that the moving speed of the sheet material is lower than a predetermined speed, it is preferable to switch the driving speed to a speed lower than the driving speed before the detection.

Therefore, when it is detected that the sheet material is slower than the predetermined speed, it is determined that the sheet material is too stiff and is not properly conveyed with respect to the predetermined driving speed by the conveying means. Is transported properly by delaying

The detection means has a sheet detection sensor for detecting the presence or absence of a sheet material, and detects the sheet based on the timing from when the sheet material starts to convey at a predetermined position to when the sheet is detected by the sheet detection sensor. It is good to detect the moving speed of the material.

The timing may be measured based on the number of pulses of a stepping motor for driving the conveying means.

If the sheet detection sensor does not detect the sheet material even after a predetermined timing, it is preferable to warn that the sheet material conveyance is abnormal.

Preferably, the conveying means has a conveying roller, and the bent path of the sheet material conveying path is provided along a substantially outer semicircular portion of the conveying roller.

[0042] The sheet detection sensor may be arranged near an intermediate portion of the semicircular portion.

A plurality of pressing members for pressing the sheet material against the conveying roller are provided, and each pressing member presses each of the pressing members according to whether the sheet to be conveyed is a cut sheet or a long continuous sheet. It may be arranged so that the pressure can be adjusted or the pressure can be released.

Further, in order to achieve the above object, the image recording apparatus of the present invention is preferably provided with recording means for recording an image on a sheet conveyed by the above-mentioned sheet conveyer.

The recording means preferably performs recording by an ink jet method.

[0046]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

Referring to FIGS. 1 to 11, a sheet conveying apparatus and an image recording apparatus according to an embodiment of the present invention will be described.

In the present embodiment, a case will be described in which the image recording apparatus is a printer that records an image by an ink jet method.

First, an overall outline of a sheet conveying apparatus and an image recording apparatus according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is an external perspective view showing a state in which an automatic sheet feeding unit (hereinafter, referred to as ASF) is mounted on the image recording apparatus according to the embodiment of the present invention, and FIG. FIG. 3 is a partially cutaway perspective view of the image recording apparatus according to the embodiment, FIG. 3 is a cross-sectional view showing a main part configuration of the ASF of FIG. 1 in a two-bin configuration, and FIG. FIG. 5 is an external perspective view showing a state in which continuous paper is set in the image recording apparatus, and FIG. 5 is a sectional view of a main part showing a case where continuous paper is fed.

The image recording apparatus 1 according to the present embodiment includes a cut sheet such as a postcard, an envelope, and a cut sheet (hereinafter also simply referred to as a cut sheet) and a fan as a sheet material as a recording medium. A continuous long continuous sheet (continuous paper) such as fold paper can be selectively used.

That is, when the cut sheet is used, the feeding is usually performed by using the ASF 30, or the feeding is performed manually.

As shown in FIG. 3, the ASF 30 is composed of two bins 30a and 30b, whereby, for example, cut sheets having different sizes are set at the same time, and two types of sizes are set in accordance with a user's selection operation. Cut paper can be used.

The feeding mechanism for each of the bins 30a and 30b has the same mechanism.

That is, a plurality of cut sheets (cut sheets are not shown in FIG. 3) stacked on the pressing plates 31a and 31b are pressed by the pickup rollers 33a and 33b by the pressing force of the springs 32a and 32b. , And are separated and fed one by one by a pickup roller 33a or 33b which rotates according to a feeding start command.

When cut paper is used, when the release lever 7 (shown in FIG. 1) as a selection control means is set to the cut paper selection state, the pinch roller 11 held by the pinch roller holder 5 is moved to the pinch roller spring 8. As a result, the sheet is urged by the conveying roller 10 as a conveying means.

The pressing force of the pinch roller at this time is
For example, 4560 gf is set.

Similarly, the auxiliary roller 16 held by the pinch roller holder 5 so as to be able to move up and down is urged by the auxiliary roller spring 9 provided on the pinch roller holder 5 toward the transport roller 10.

The pressing force of the auxiliary roller 16 at this time is set to, for example, 2400 gf.

As a result, the cut sheet fed from the ASF 30 is transferred to the transport motor 216 as a stepping motor.
2 (shown in FIG. 2), a sheet material conveyance path having a curved path formed around the conveyance roller 10 (substantially a semicircular portion of the conveyance roller 10) is conveyed to the recording area side by the rotation of the conveyance roller 10 driven by (shown in FIG. Is done.

On the recording area side, a needle roller 12 as a sheet material pressing means is held by a needle roller holder 17, and is urged against the transport roller 10 by a needle roller spring 18 as a pressing force applying means.

At this time, the needle roller spring 18 bends due to the protrusion 27c of the release shaft 27, and the elastic force of the needle roller spring 18 (leaf spring) about the intersection 18a as a center and the pressing force applying means. The compression force of the needle assisting spring 19 (coil spring) generates a pressure contact force.

The pressing force of the needle roller 12 at this time is, for example, from the needle roller spring 18 to 127.
0 gf and the needle assist spring 19 to 200 gf
Is set to 1470 gf in total.

The pinch roller 11, the auxiliary roller 1
6, and the needle roller 12 constitute a pressing member.

The cut sheet is further conveyed by a conveying force to be conveyed between the recording head 20 and the platen 24.

The conveyance here is performed by one of the recording heads 20.
The conveyance amount is intermittently performed for each scan, and the conveyance amount is determined by a plurality of recording units provided in the recording head 20 as an image forming unit (in the case of a printer having an inkjet recording head, the ink ejection port, In the case of a wire impact printer, this is performed in accordance with the arrangement length of the wire) in the transport direction of the cut sheet.

The cut sheet on which the recording is performed by the recording head 20 during the conveyance for each scan and the rotation of the gap roller 13 and the discharge roller 14 (and the gap roller wheel 13a pressed by the rollers) ,
The paper is sequentially conveyed to the upper part of the apparatus by the paper ejection roller first wheel 14a), and is discharged by the paper ejection roller second wheel 14b.

When continuous paper (fanfold paper) is used, the ASF 30 is not used. As shown in FIG. 4, the continuous paper fed from the feed port 35 is a pin feed tractor (hereinafter referred to as a second transport means). Pinch tractor) 3
Is transported by the drive of.

When the release lever 7 (see FIG. 1) is set to the continuous paper selection state, the release shaft 27 rotates, and the projection 27b is moved to the pinch roller holder 5 as shown in FIG.
Is pressed, the pinch roller 11 is separated from the transport roller 10 and retracted from the transport path.

The pinch roller holder 5 has a pivot point provided on the needle roller holder 17 side, and the auxiliary roller 1 held by the pinch roller holder 5 so as to be vertically movable.
Similarly, the roller 6 moves in a direction away from the transport roller 10, but the auxiliary roller spring 9 reduces the transport force to the transport roller 10.

Further, the pressing of the projection 27c against the needle roller spring 18 is completely released.

However, the urging force of the needle assisting spring 19 (coil spring) is not released, so that the pressing force of the needle roller 12 against the transporting roller 10 during the transport of the continuous paper is reduced by a spring other than the needle assisting spring 19. Irrespective of the biasing state of the motor, the appropriate pressure can always be maintained.

For example, the pressing force of the auxiliary roller 16 at this time is 200 gf, and the pressing force of the needle roller 12 is 200 gf.

Although the pressing of the needle roller spring 18 is released, when the displacement of the needle roller holder 17 becomes large due to the continuous paper passing through the needle roller 12, a pressure contact is applied. .

The continuous paper conveyed to the recording area under a total pressing force of, for example, 400 gf is sequentially moved to the upper side of the apparatus by intermittent conveyance of the recording head 20 for each scan similarly to the case of the cut paper described above. , And recording is performed during this time.

Next, the detailed mechanism of the transport roller unit in the transport state of cut paper and continuous paper will be described with reference to FIGS.

FIG. 6 is a schematic sectional view of a sheet conveying apparatus according to an embodiment of the present invention. FIG. 6A shows a cut sheet conveying state, and FIG. 6B shows a continuous sheet conveying state. .

FIG. 7 is an arrangement diagram for explaining the pressing positions of the pinch roller 11, the auxiliary roller 16, and the needle roller 12 against the transport roller 10.

As shown in FIG. 6A, the pinch roller 1
1, the auxiliary roller 16 and the needle roller 12 are pressed against the transport roller 10 as described above.

At this time, the guide member 26 is
0 is cut out and held coaxially with the transport roller 10.

The guide member 26 presses each of the press-contact portions 10a and 10b of the pinch roller 11, the auxiliary roller 16 and the needle roller 12 in the conveying direction B of the recording medium.
In 10c, it is set so that no convex portion is formed with respect to the diameter of the transport roller 10.

Further, as shown in FIG. 7, the guide members 26 are disposed at positions 28 and 29, and the main scanning direction in which the contact interval between the conveying roller 10 and the sheet material is orthogonal to the sheet conveying direction. It is made to be almost constant in the direction.

By arranging the guide member 26 in such a manner, it is possible to prevent a reduction in the conveying force in the feeding section and the sheet reversing section that require a conveying force in a so-called U-turn path.

FIG. 6B shows a case where the continuous paper is conveyed. The pinch roller 11 is completely separated, and the auxiliary roller 16 and the needle roller 12 have a reduced pressure contact force.

The continuous paper is fed to the conveying roller 1 of the guide member 26.
It is conveyed on the convex portions 26a and 26b corresponding to 0.

As described above, the guide members 26 are arranged at substantially constant intervals in the main scanning direction orthogonal to the sheet material conveyance direction, and the auxiliary roller 16 presses the continuous paper against the conveyance roller 10. Since there is no pressing force enough to make the continuous paper, the continuous paper does not substantially obtain the conveying force from the conveying roller 10 except for the pressing portion of the needle roller 12.

Here, a gap is provided between the auxiliary roller 16 and the transport roller 10 in the portion of 10d.
Although the auxiliary roller 16 is in contact with the continuous paper,
This is to schematically show that it does not touch.

Further, since the guide member 26 is held coaxially with the conveyance roller 10, the projection 26
It is possible to accurately manage the protrusion amounts of a and 26b.

For example, for example, the diameter D of the conveying roller 10
φ38.808 mm, and the above rollers 11, 16, 1
The radius R of the guide member 26 at the pressure contact portion 2 is R = 1.
The projections 26a and 26 of the guide member 26 are set to 8.9 mm.
It is preferable that b is a protrusion of about 0.5 mm from the conveyance roller 10.

The reason why the pressing force of the needle roller 12 against the conveying roller 10 is set to be a weak pressing force is that the conveying accuracy of the continuous sheet is usually controlled by the pin tractor 3. This is because if the value is set to “0”, the needle roller 12 may be separated from the surface of the transport roller 10 due to a sheet joint (perforation).

In this apparatus, in order to prevent this, the needle roller 12 is pressed against the transport roller 10 with an appropriate pressing force.

For example, as described above, the pressing force of the needle roller 12 against the conveyance roller 10 is set to 1270 gf when a single-sheet sheet is selected, and is set to 2270 gf when a continuous sheet is selected.
It is good to be 00gf.

On the other hand, the reason why the pressing force of the auxiliary roller 16 against the transport roller 12 is set to a low pressure is that the sheet detection sensor 4 disposed near the auxiliary roller 16 detects the sheet as shown in FIGS. This is to reduce the error of the sheet detection position at the sensor arrangement position P1.

That is, the sheet material conveyed by the conveyance roller 10 is wound around the conveyance roller 10 and conveyed due to its weight (expressed in terms of basis weight, continuous weight, etc.) or its stiffness due to its type. Case (weak seat)
And a case where the sheet is conveyed along the roller facing portion 6a of the paper pan 6 (a strong sheet).

Here, the pressing force of the auxiliary roller 16 is "0".
In this case, the auxiliary roller 16 is separated from the peripheral surface of the transport roller 10 due to the weight or stiffness of the sheet.

That is, by pressing the auxiliary roller 16 against the conveying roller 10 with an appropriate pressing force, the sheet conveyed in the vicinity of the sheet detection sensor 4 is always conveyed while being wound around the conveying roller 10. Therefore, the detection error by the sheet detection sensor 4 can be reduced.

For example, as described above, the pressing force of the auxiliary roller 16 against the conveyance roller 10 is set to 2400 gf when a single-sheet sheet is selected, and 200 gf when a continuous sheet is selected.
up to f.

The sheet detection sensor 4 constituting the detection means will be briefly described. The sheet detection sensor 4 is a sensor capable of detecting the presence or absence of a sheet material. This sensor detects the presence or absence of the sheet material at a predetermined detection position. By detecting that the sheet material has not yet arrived,
It can detect that the sheet material has arrived, is being conveyed, has passed, and the like.

In the present embodiment, the transport speed of the sheet material is detected by measuring the time from when the sheet material starts to be transported at a predetermined position to when the sheet material is detected by the sheet detection sensor 4. doing.

In the present embodiment, the sheet detection sensor 4 is arranged near the auxiliary roller 16 (near the middle of the bending path (semicircle)), so that the sheet detection sensor 4 is located at the most upstream position in the bending path. The conveying speed (moving speed) of the conveyed sheet material is detected based on the applied conveying force (the conveying force obtained by the nip between the conveying roller 10 and the pinch roller 11) (however, the cut sheet is conveyed). Case).

Next, control means for controlling the driving of each member having the above-described structure will be described with reference to FIG.

FIG. 8 is a block diagram of a control system of the image recording apparatus according to the embodiment of the present invention.

Control unit 2 for sending drive control signals for each member
10 is a CPU 210a, ROM 210b, RAM 210
c, and a counter 210d.

The CPU 210a is a central processing unit which reads out programs and various data from the ROM 210b and the like, performs necessary calculations and judgments, and performs various controls.

The ROM 210b is a read-only memory, and stores various programs required for the operation of the CPU 210a, character codes, and various data necessary for recording dot patterns.

A RAM 210c is a read / write memory, and a working area in which the CPU 210a temporarily stores data in a command and a calculation result, or an external device 211.
It is composed of a buffer area for storing various data input from the above.

The counter 210d counts the number of drive pulses of the transport motor 216 and transmits the information to the CPU.

The control unit 210 includes an interface 212
, An image signal from the external device 211, a sheet detection signal from the sheet sensor 4 or the like, or the operation panel 21
8 and the like.

The control unit 210 outputs a drive signal to motor drivers 213 and 214 for driving the conveyance motor 216 and the carriage motor 217 based on a program, and a head driver 215 for driving the recording head 20. To output a drive signal.

Here, the controller 210 controls the transport motor 216
As described above, there are two modes in which a drive signal is output using a cut sheet (normal cut sheet and thick cut sheet) selected by the release lever 7 (see FIG. 1) and a mode in which continuous paper is used. There are types.

Next, a control procedure by the control means when a cut sheet is conveyed and recording is performed on the cut sheet will be described with reference to FIGS.

FIG. 9 is a flowchart illustrating a control procedure of the image recording apparatus according to the embodiment of the present invention. FIG. 10 is a timing chart of sheet conveyance.
1 is a schematic cross-sectional view of a transport unit in a cut sheet transport state.

[0113] The transport of the continuous paper is the same as that of the known art (prior art), and therefore the description thereof is omitted.

In the case of the cut sheet mode, first, it is determined whether or not the sheet sensor 4 is ON.

When the sheet sensor 4 is ON,
Since a recording sheet exists in the transport path, no new sheet transport is performed.

On the other hand, when the sheet sensor 4 is turned off, the recording sheet P is not in the apparatus, the sheet is being discharged, or the recording on one sheet P is almost completed. For this reason, the recording sheet P is completely discharged out of the apparatus.

After the recording sheet P is completely discharged out of the apparatus, it is determined whether or not the cut sheet transport mode is set.

In the case of the cut sheet transport mode, FIG.
As shown in FIG. 1, by rotating the pickup roller 33a or 33b in the ASF shown in FIG. 3, the recording sheet P positioned and applied to the nip portion between the stopped transport roller 10 and the pinch roller 11 is moved. Transport.

At the time of this conveyance, the number of drive pulses of the conveyance motor (stepping motor) 216 at the moment when the leading end of the recording sheet P turns on the sheet detection sensor 4 is counted. It is determined that the cut paper (weak) is being conveyed, and the conveyance speed is not changed.

However, if the number of drive pulses of the transport motor 216 is larger than the set value, the transport roller 1
Assuming that a slippage has occurred between the recording sheet P and the recording sheet P being conveyed, it is determined that the thick paper is being conveyed, the conveying speed is reduced, the torque of the conveying motor 216 is increased, and control is performed to prevent loss of synchronization.

That is, when the transport speed is f ₁ (pulse / s)
The drive frequency of the transport motor 216 is set so that
The drive is performed at that frequency until the sheet sensor 4 is turned on.

Then, it is determined whether or not to change the transport speed based on the number of drive pulses of the transport motor 216.

Hereinafter, a more specific example will be described.

For example, as shown in FIG. 10, when the sheet motor 4 is driven by the conveyance motor 216 at a driving frequency at which the conveyance speed becomes f ₁ (pulses / s) until the sheet sensor 4 is turned on, the conveyance is performed in about the first 10 pulses. The speed is accelerated to f ₁ , and at the speed f ₁ , at the position where the sheet sensor 4 is turned on (in theory, the sheet sensor 4 is driven up to 543 pulses), the ON timing of the sheet sensor 4 becomes 17 times the theoretical value. When the pulse is smaller than the pulse, that is, 543 + 17 =
If the number of pulses is equal to or less than 560 pulses, it is determined that the sheet is a normal cut sheet, and the conveyance speed is not changed thereafter.

However, when the ON timing of the sheet sensor 4 exceeds 560 pulses, it is determined that the sheet is thick paper, and the drive of the transport motor 216 is performed so that the transport speed becomes f ₂ (pulses / s) lower than f _1. Decelerate the frequency using about 10 pulses.

At this time, the number of pulses of the transport motor 216 becomes
If the sheet sensor 4 is not turned on even when the number of pulses reaches 590 or more, an error occurs as a sheet material conveyance error.

In this case, it is desirable to give a warning to the outside of the apparatus so as to urge the user to clear the jam.

In both cases where the transport speed is f ₁ or f ₂ ,
When the leading edge of the sheet P is detected by the sheet sensor 4, the transport motor 216 is driven for 412 pulses.

After that, the sheet P is decelerated by using about 10 pulses from the respective conveying speeds f ₁ and f ₂ and then stopped, so that the leading end of the sheet P is conveyed to the recording position by the recording means 20 over the needle roller 12, The cue has been performed.

In this embodiment, when the conveyance motor 216 drives one pulse, the recording sheet P is reduced by one.
/ 360 inches of paper are set.

For this reason, in the timing chart of FIG. 10, the leading end of the recording sheet P is detected by the sheet sensor 4 around the 543th pulse. The path length to the sheet sensor 4 is set to about 543/360 inches.

Then, from the time when the sheet sensor 4 detects the sheet, the cueing is performed at 422/360 inches.

That is, the transport roller 10 and the pinch roller 1
From the nip portion 1, the detection position of the sheet sensor 4 is set to a predetermined value of 543 pulses, and 422 pulses are added thereto. The predetermined value of 543 to 560 pulses is determined to be a normal cut sheet, but the predetermined value of 560 to 589 pulses is determined to be a thick sheet, the conveyance speed is reduced, and cueing to the recording unit is performed.

When the cueing of the recording sheet P is completed in this way, an image is recorded by a predetermined recording operation.

When one-line printing is completed, the conveying motor 216 is driven to convey the recording sheet P by one line, and recording is performed in the same manner.

As described above, when the recording on one recording sheet P is completed, the recording sheet P is discharged by driving the transport motor 216, and the sheet transport and the recording operation are completed.

As described above, the actual moving speed of the sheet material with respect to the predetermined driving speed by the conveying means is an appropriate speed (in the case of a weak (thin) sheet material in which slippage is difficult to occur) or a slow speed. Depending on whether the sheet is a strong (thick) sheet material in which slip is likely to occur, switching control of the driving speed is performed, and appropriate conveyance can be performed according to each.

That is, in the case of a sheet material having a weak (thin) stiffness, by carrying the sheet while maintaining the driving speed, it becomes possible to carry the sheet while maintaining the processing speed.

In the case of a stiff (thick) sheet material, the stepping motor is prevented from stepping out by reducing the driving speed, thereby enabling stable conveyance.

In the above description, a case has been described in which two-stage control is performed in which the driving speed is kept or reduced depending on whether the moving speed of the sheet material is faster or slower than the predetermined speed. Control for changing the driving speed in a plurality of stages according to the moving speed can also be performed.

[0141]

According to the sheet conveying apparatus of the present invention, the moving speed of the sheet material is detected by the detecting means with respect to the predetermined driving speed by the conveying means, and the driving speed of the conveying means after the detection is switched. In addition, the conveyance according to the conveyance state of the sheet material in the bending path can be performed, and the stable sheet conveyance can be performed, and the reliability is improved.

If the detecting means detects the moving speed of the conveyed sheet material on the basis of the conveying force applied by the conveying means in the vicinity of the most upstream portion of the bent path, the detecting means quickly responds to the conveying state of the sheet material. Transport is possible.

If the detecting means detects that the moving speed of the sheet material is lower than the predetermined speed, the sheet material is strong and is properly conveyed at the predetermined driving speed by the conveying means. It is determined that there is no transfer, and proper conveyance can be performed by reducing the driving speed.

The moving speed of the sheet material can be detected based on the timing from when the sheet material starts to convey at a predetermined position to when the sheet is detected by the sheet detection sensor.

Note that the timing can be measured by the number of pulses of the stepping motor for driving the conveying means.

When the sheet material is not detected by the sheet detection sensor after a predetermined timing,
It is possible to warn that sheet material conveyance is abnormal.

By providing a plurality of pressing members for pressing the sheet material against the conveying roller so that the pressing force can be adjusted or the pressing can be released, the case where the sheet to be conveyed is a cut sheet and the case where a long continuous sheet is used. The transport according to the case can be performed.

Further, the image recording apparatus of the present invention can be provided with a highly reliable sheet material conveying apparatus as described above.

Incidentally, as the recording means of the image recording apparatus, recording can be performed by an ink jet system.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing a state in which an automatic paper feeding unit is mounted on an image recording apparatus according to an embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view of the image recording apparatus according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a main configuration of the ASF of FIG. 1 in a two-bin configuration.

FIG. 4 is an external perspective view illustrating a state where continuous paper is set in the image recording apparatus according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view of a main part showing a case where continuous paper is fed.

FIG. 6 is a schematic cross-sectional view of the sheet conveying apparatus according to the embodiment of the present invention.

FIG. 7 is an arrangement diagram for explaining a pressing position of a pinch roller, an auxiliary roller, and a needle roller with respect to a transport roller.

FIG. 8 is a block diagram of a control system of the image recording apparatus according to the embodiment of the present invention.

FIG. 9 is a flowchart illustrating a control procedure of the image recording apparatus according to the embodiment of the present invention.

FIG. 10 is a timing chart of sheet conveyance.

FIG. 11 is a schematic cross-sectional view of a transport unit in a cut sheet transport state.

FIG. 12 is a cross-sectional configuration explanatory view showing the configuration of a sheet material transporting device according to the related art when a cut sheet is selected.

FIG. 13 is a cross-sectional configuration explanatory view showing a configuration of a sheet material conveying apparatus according to a conventional technique when a continuous sheet is selected.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 image recording device 3 pin feed tractor 4 sheet detection sensor 5 pinch roller holder 6 paper pan 7 release lever 8 pinch roller spring 9 auxiliary roller spring 10 transport roller 11 pinch roller 12 needle roller 13 gap roller 14 discharge roller 16 auxiliary roller 17 Needle roller holder 18 Needle roller spring 19 Needle auxiliary spring 20 Recording head 24 Platen 26 Guide member 27 Release shaft 28, 29 Guide member arrangement position 30 ADF 30a, 30b Bin 31a, 31b Press plate 32a, 32b Spring 33a, 33b Pickup roller P1 Sheet detection sensor arrangement position 35 Feeding port P Recording sheet 216 Transport motor 210 Control unit

Claims (11)

[Claims] 1. A sheet conveying path having a bent path,
A conveying means for conveying the sheet material along the sheet material conveying path, wherein a moving speed of the sheet material with respect to a predetermined driving speed by the conveying means at a predetermined position in the bending path is detected. A sheet conveying device for controlling the switching of the driving speed of the conveying unit after the detection based on the detection result of the detecting unit. 2. The apparatus according to claim 1, wherein said detecting means detects a moving speed of the conveyed sheet material based on a conveying force applied by said conveying means in the vicinity of the most upstream portion of the bending path. 2. The sheet material conveying device according to 1. 3. The method according to claim 1, wherein when the detecting means detects that the moving speed of the sheet material is lower than a predetermined speed, the driving speed is switched to a speed lower than the driving speed before the detection. Or the sheet conveying device according to 2. 4. The detecting means has a sheet detecting sensor for detecting the presence or absence of a sheet material, based on a timing from when the sheet material starts to convey a predetermined position to when a sheet is detected by the sheet detecting sensor. The sheet conveying device according to claim 1, wherein the moving speed of the sheet is detected by using the sheet conveying device. 5. The sheet conveying apparatus according to claim 4, wherein the timing is measured based on the number of pulses of a stepping motor for driving the conveying unit. 6. The apparatus according to claim 4, wherein when the sheet detection sensor does not detect the sheet material even after a predetermined timing, a warning that the sheet material conveyance is abnormal is issued. Sheet material transport device. 7. The sheet conveying device according to claim 1, wherein said conveying means has a conveying roller, and the bent path of said sheet material conveying path is provided along a substantially outer circumferential semicircular portion of said conveying roller. A sheet material conveying device according to one of the above. 8. The sheet conveying apparatus according to claim 7, wherein said sheet detection sensor is disposed near an intermediate portion of said semicircular portion. 9. A plurality of pressing members for pressing a sheet material against said conveying roller, wherein said pressing member is arranged in accordance with whether a sheet to be conveyed is a cut sheet or a long continuous sheet. 9. The sheet conveying apparatus according to claim 7, wherein each of the pressing members is arranged such that the pressing force can be adjusted or the pressing force can be released. 10. An image recording apparatus comprising a recording means for recording an image on a sheet conveyed by the sheet conveying apparatus according to claim 1. Description: 11. An image recording apparatus according to claim 10, wherein said recording means performs recording by an ink jet system.