JP4261722B2 - Sheet feeding apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet feeding apparatus for feeding one sheet at a time from stacked sheets and an image forming apparatus including the sheet feeding apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, sheet feeding apparatuses that feed sheets one by one from stacked sheets are widely known, and are used in, for example, image forming apparatuses such as printers, copiers, and facsimiles.
[0003]
Such a sheet feeding apparatus generally includes a feeding roller and a conveyance roller, and firstly feeds the sheet one by one by the feeding roller and conveys the fed sheet further downstream by the conveyance roller. is there.
[0004]
Here, in order to perform conveyance in accordance with a predetermined timing, for example, in the case of an image forming apparatus, in order to form an image at an appropriate position on a sheet, it is conveyed toward the image forming unit at a predetermined timing. In addition, it is configured such that the resist is removed by a transport roller and transported.
[0005]
For example, Japanese Patent Laid-Open No. 11-79465 discloses a sheet having a conveyance roller, a feeding roller, and a clutch mechanism that selectively transmits driving from a single drive source to the feeding roller and the conveyance roller. A technique related to a feeding device is disclosed.
[0006]
In this case, the sheet fed by the rotation of the feeding roller abuts on the stopped conveying roller to perform the registration operation.
[0007]
In addition to this, there is a type in which the same driving source is used, and the feeding roller rotates normally in both cases when the conveying roller is rotated forward and backward. That is, the feeding roller is rotated forward by the reverse rotation of the motor, and the sheet fed thereby hits the conveying roller that is rotating in reverse, so that the registration operation is performed.
[0008]
Further, there is a type in which a separate driving source is provided for each of the feeding roller and the conveying roller, and switching means such as a clutch is eliminated. In this case, the registration operation is performed by abutting the leading end of the sheet against the stopped conveyance roller.
[0009]
[Problems to be solved by the invention]
However, in the case of the prior art as described above, the following problems have occurred.
[0010]
However, in recent years, various types of sheets used in printers and the like have come out according to applications, and there are differences in resist properties and sheet transport properties after resist depending on the thickness and material of the sheets.
[0011]
Here, in the case of one driving source of the above-described conventional example, the driving operation is switched and the registration operation is performed. Therefore, as a control mode during the registration operation, control for changing the feeding speed and registration operation are performed. Only the control for switching whether or not to perform the control, or the control for changing the abutting amount to the conveying roller according to the type of the sheet can be performed. Also, the control of sheet conveyance after registration cannot be changed.
[0012]
In addition, even when the feeding roller and the conveying roller have independent drive sources, the control during the registration operation is similar to that of a single driving source, whether or not the feeding speed and the registration operation are performed. In addition, there is no special control for the post-registration conveyance to the extent that the abutting amount is changed.
[0013]
Therefore, depending on the type of sheet, an appropriate resist may not be performed, or conveyance after the resist may not be performed appropriately.
[0014]
The present invention has been made in order to solve the above-described problems of the prior art, and an object of the present invention is to provide a sheet feeding apparatus having excellent quality and capable of appropriate feeding corresponding to various sheets. And providing an image forming apparatus.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, a feeding roller that feeds stacked sheets, a conveying roller that conveys a sheet fed by the feeding roller downstream, and the conveying roller Stop when the pinch roller to be urged and the sheet to be fed are not cardboard or envelope, but a sheet that forms a loop when the leading end abuts against the nip between the conveying roller and the pinch roller The first operation of performing the registration operation by abutting the leading end of the sheet against the nip is performed, and if the sheet to be fed is not a cardboard or an envelope but the first operation is performed, a loop is not formed. In this case, a second operation is performed in which the leading edge of the sheet is brought into contact with the nip between the conveying roller and the pinch roller that are reversed so that the sheet to be fed is thick paper. Is a sheet feeding apparatus comprising a control unit that performs a third operation that does not perform a registration operation while the conveyance roller is rotated forward when the envelope is an envelope, wherein the control unit includes the first unit When carrying out the operation or the second operation and conveying the sheet whose leading end is in contact with the nip downstream, if the sheet is a sheet that easily enters the nip, the feeding roller and the conveying roller are simultaneously A fourth operation of rotating is performed, and when the sheet is a sheet that is difficult to enter the nip, a fifth operation of rotating the conveying roller is performed after the feeding roller is rotated .
[0016]
In addition, when the second operation is performed, the control unit may stop the feeding roller after stopping the feeding roller.
[0023]
Further, in the image forming apparatus of the present invention, the above sheet feeding device,
Image forming means for forming an image on a sheet fed by the sheet feeding device.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.
[0025]
The sheet feeding apparatus according to the embodiment of the present invention is applied to various image forming apparatuses such as a printer and a copying machine. However, since the image forming apparatus is a known technique, only a brief description will be given. In the following description, the sheet feeding apparatus will be described in detail.
[0026]
A sheet feeding apparatus and an image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS. Note that an ink jet printer will be described as an example of the image forming apparatus.
[0027]
FIG. 1 is a perspective view of an image forming apparatus (inkjet printer) using a sheet feeding apparatus according to an embodiment of the present invention (a perspective view showing a state in which the inside is opened so that the inside can be seen), and FIG. FIG. 3 is a schematic cross-sectional view of a sheet feeding apparatus according to an embodiment of the present invention, and FIGS. 3 to 5 are also schematic cross-sectional views of the sheet feeding apparatus according to the embodiment of the present invention (feed operation is performed). FIG. 6 is an explanatory diagram showing operation control of the sheet feeding apparatus according to the embodiment of the present invention.
[0028]
First, the general configuration and operation of the entire apparatus will be described with reference to FIGS.
[0029]
The pressure plate 101 of the feeding unit 100 is rotatably supported, and the sheet S is stacked thereon. During feeding, the feeding roller 103 is rotated by a feeding motor 104 as a driving source and the pressure plate 101 is rotated toward the feeding roller 103 by the pressure plate spring 102, so that the uppermost sheet S is moved to the feeding roller 103. Pressed.
[0030]
When the feeding roller 103 rotates in this state, the stacked sheets S are separated and fed one by one from the top by the separation claw 105 and sent to the conveying unit 200.
[0031]
Here, the sheet conveying speed at the time of feeding is changed according to the type of the sheet. More specifically, if the sheet is thick and stiff, reduce the transport speed. Conversely, if the sheet is thin and weak, such as plain paper, increase the transport speed. ing. This is because in the former case, if the conveyance speed is increased, the stability at the time of conveyance deteriorates, so that it cannot be performed too quickly.
[0032]
When the sheet S is sent to the conveyance unit 200, the PE sensor lever 603 is rotated by being pushed by the leading edge of the sheet S, and thereby the leading edge position of the sheet S is detected by the PE sensor 602.
[0033]
When performing the registration operation, the sheet S is conveyed by a predetermined amount when the leading edge of the sheet is detected, and a registration operation is performed between the conveyance roller 201 and the pinch roller 202 (nip portion) (see FIG. 4). State shown).
[0034]
Here, the conveyance roller 201 is configured to be driven by a conveyance motor 207 (which is driven and controlled independently of the feeding motor 104) as a drive source, and the pinch roller 202 is driven by a pinch roller spring 206. It is pressed against the conveyance roller 201.
[0035]
After the registration operation is performed, the sheet S is transported on the platen 203 by the transport roller 201 and the pinch roller 202.
[0036]
Here, the sheet conveyance speed at the time of conveyance cueing is also changed according to the type of sheet. More specifically, for the same reason as in the case of feeding described above, in the case of a thick and stiff sheet, the transport speed is slowed, and conversely, it is thin and thin like plain paper. If the sheet is weak, the conveyance speed is increased.
[0037]
At this time, the feed roller 103 also rotates at the same paper feed speed as the transport roller 201, and the light shielding plate 106 provided on the feed roller 103 shields the feed roller sensor 601 so that the position of the feed roller 103 is changed. Detected, the feeding roller 103 stops at the initial position (state shown in FIG. 5).
[0038]
The conveyed sheet S is printed by the recording head 400 as an image forming unit supported by the carriage 300 while being held by the platen 203. Then, it passes between the paper discharge roller 204 and the paper discharge spur 205 and is discharged out of the apparatus.
[0039]
The carriage 300 is guided by a guide shaft 501 and a guide rail 502, and is driven by transmitting the driving from the carriage driving motor 503 to the carriage 300 by the timing belt 504.
[0040]
Next, operation control of the feeding roller 103 and the conveying roller 201 during sheet feeding will be described with reference to FIG.
[0041]
The embodiment of the present invention is characterized in that the operation control of the registration operation and the sheet conveyance start operation after the registration operation can be changed.
[0042]
First, regarding the registration operation, operation control of the feeding roller 103 and the conveyance roller 201 will be described. In the example shown below, the registration operation is switched to the following three types of operations depending on the type of sheet, and each control is performed (registration operation switching control).
[0043]
(A) In normal registration operation (when the conveyance roller is stopped and the feeding roller is rotated to perform registration operation) (First operation)
After the feeding command (S0) is issued, a sheet (such as plain paper) that can align the leading edge of the sheet by a normal registration operation (more specifically, feeding with the conveying roller 201 stopped) When the sheet is fed by the roller 103, the sheet is formed with a loop, or the leading end of the sheet is stopped at a predetermined position (the conveyance nip portion between the stopped conveyance roller 201 and the pinch roller 202). In the case of a sheet that slips between the rollers 103 (S1), control is performed so that registration is performed with the conveying roller 201 stopped (S3).
[0044]
That is, the sheet S fed by the feeding roller 103 hits the stopped conveyance roller 201 (the conveyance nip portion between the conveyance roller 201 and the pinch roller 202), and a loop is formed as shown in FIG. The resist is performed by. Alternatively, when the strain of the sheet S is strong, the loop is not formed, and registration is performed by causing a slip between the feeding roller 103 and the sheet S while the leading edge of the sheet S is stopped. In addition, after the registration is performed, that is, after the front end of the sheet S is abutted against the conveying roller 201 by a predetermined amount, the feeding roller 103 is also stopped (S4).
[0045]
(B) When the registration operation is performed by reversing the conveyance roller (second operation)
After the feeding command (S0) is issued, a sheet that cannot be properly registered if the conveying roller 201 is stopped (more specifically, the feeding roller 103 with the conveying roller 201 stopped). When the sheet is fed, the leading edge of the sheet S is not stopped at a predetermined position (the conveyance nip portion between the conveyance roller 201 and the pinch roller 202) and is pushed into the conveyance nip portion by the conveyance roller 201) In this case, control is performed so that the registration is performed in a state where the conveying roller 201 is reversed.
[0046]
That is, when the sheet is very strong and no loop is formed at the time of abutting, or when the sheet is strong and the resistance between the surface of the sheet and the feeding roller 103 is large, as in the case of (a) above. In the case where slippage is unlikely to occur between the sheet surface and the feeding roller 103 with the leading edge of the sheet abutting against the conveying roller 201 (S5), the sheet is conveyed in a state where the resist is not sufficiently formed. In some cases, the leading edge of the sheet is pushed into the conveyance nip portion between the roller 201 and the pinch roller 202.
[0047]
On the other hand, it may be possible to increase the pressure of the pinch roller spring 206 to make it difficult to be pushed in. Will occur.
[0048]
Therefore, in the present embodiment, when the sheet S hits the conveyance roller 201, the conveyance roller 201 is rotated in the reverse direction to prevent the leading edge of the sheet from being pushed in (S6, S7).
[0049]
When the feeding roller 103 and the conveying roller 201 are stopped, a predetermined amount of sheets are abutted, the feeding roller 103 is first stopped (S8), and then the reverse rotation of the conveying roller 201 is stopped (S9). Thereby, the resist is surely performed.
[0050]
(C) When the registration operation is not performed (third operation)
When a registration operation is performed after the feeding command (S0) is issued and a sheet that interferes with conveyance after registration is conveyed, the registration operation is not performed while the conveyance roller 201 is rotated in the sheet conveyance direction. To control.
[0051]
That is, when the sheet material is thick or the tip is swelled (envelope folding part, etc.) (S15), the post-registration transfer may not be performed successfully when the registration operation is performed. Therefore, the registration operation is not performed (S16). The reason why the conveyance after registration is not performed well is that, in the case of a sheet such as thick paper or an envelope, if the registration operation applied to the nip is performed while the conveyance roller 201 is stopped or reversed, the sheet is thick. This is because the pinch roller pressure may not be able to pass through the nip. Therefore, by rotating the conveyance roller 201 in advance, it is easy to pass through the nip, and stable feeding is possible.
[0052]
In such a case, assuming that the conveyance roller 201 rotates in the sheet S conveyance direction is normal rotation, the conveyance roller 201 is rotated in the normal rotation direction when the sheet S is fed. Does not stop at the transport nip portion of the transport roller 201, and is sandwiched between the transport roller 201 and the pinch roller 202 and transported to the platen 203 (S17). Thereafter, printing is started (S18).
[0053]
Next, regarding the conveyance start operation after the registration operation (the operation when the sheet is conveyed to the print start position (S10)) when the registration operation (in the cases (a) and (b) above) is performed. The operation control of the feeding roller 103 and the conveying roller 201 will be described.
[0054]
In the example shown below, regarding this operation, the following two types of operations are switched according to the type of sheet, and each control is performed (conveyance start operation switching control).
[0055]
(A) When the feed roller 103 and the transport roller 201 start to rotate simultaneously (fourth operation)
In the case of a normal sheet (a sheet that easily enters the conveyance nip portion between the conveyance roller 201 and the pinch roller 202) such as plain paper (S11), after the registration, the feeding roller 103 and the conveyance roller 201 are Control is performed so as to perform the rotation operation simultaneously (S12).
[0056]
Then, the feeding roller 103 rotates to the initial position and stops, and the conveying roller 201 cues the sheet S to the printing position and stops. Thereafter, printing is started (S18).
[0057]
(B) When the feed roller 103 starts rotating before the transport roller 201 (fifth operation)
In the case of a sheet that is difficult to enter the conveyance nip portion by the conveyance roller 201, control is performed so that the conveyance roller 201 is rotated after the feeding roller 201 is rotated.
[0058]
That is, when the registration operation is a sheet that is difficult to form a loop or a thick sheet (S13), the rotation of the feeding roller 103 is started before the conveyance roller 201 after registration (S14). As a result, when cueing and feeding are performed simultaneously as in (A) above, even if it is difficult to enter the feeding nip portion between the feeding roller 201 and the pinch roller 202, the feeding roller 103 is first moved. , The leading edge of the sheet S can easily enter the conveyance nip portion. Thereafter, printing is started (S18).
[0059]
【The invention's effect】
As described above, according to the present invention, by performing the registration operation switching control, when performing the registration operation, the conveyance roller is stopped and the registration is performed, and the conveyance roller is rotated in the direction opposite to the conveyance direction. Therefore, it is possible to perform the feeding corresponding to various sheets, and the quality is excellent.
[0060]
In addition, by carrying out the conveyance start operation switching control, when the feeding roller and the conveyance roller are simultaneously rotated to start conveyance, and when the conveyance roller is rotated after the feeding roller is rotated and conveyance is started Since it can be switched, it is possible to perform feeding corresponding to various sheets, and the quality is excellent.
[Brief description of the drawings]
FIG. 1 is a perspective view of an image forming apparatus using a sheet feeding apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of a sheet feeding apparatus according to an embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view (feed operation explanatory diagram) of the sheet feeding apparatus according to the embodiment of the present invention.
FIG. 4 is a schematic cross-sectional view (feed operation explanatory diagram) of the sheet feeding apparatus according to the embodiment of the present invention.
FIG. 5 is a schematic cross-sectional view (feed operation explanatory diagram) of the sheet feeding apparatus according to the embodiment of the present invention.
FIG. 6 is an explanatory diagram showing operation control of the sheet feeding apparatus according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 Feed part 101 Pressure plate 102 Pressure plate spring 103 Feed roller 104 Feed motor 105 Separation claw 106 Shading plate 200 Conveyance part 201 Conveyance roller 202 Pinch roller 203 Platen 204 Discharge roller 205 Discharge spur 206 Pinch roller spring 207 Conveyance motor 300 Carriage 400 Recording head 501 Guide shaft 502 Guide rail 503 Carriage drive motor 504 Timing belt 601 Feed roller sensor 602 PE sensor 603 PE sensor lever

Claims (3)

A feeding roller for feeding the stacked sheets;
A conveying roller for conveying a feed sheets by the feed roller downstream,
A pinch roller biased by the transport roller;
When the sheet fed by the sheet when abutted against a nip tip of the conveying roller and the pinch roller is stopped rather than cardboard or an envelope loop is formed, the sheet to the nip is stopped The first operation for performing the registration operation with the tip abutted is performed ,
When the sheet to be fed is not a cardboard or an envelope and a loop is not formed when the first operation is performed, the leading end of the sheet is abutted against the nip between the conveying roller and the pinch roller which are reversed. Perform a second operation to perform the resist operation ,
When the sheet to be fed is cardboard or an envelope, a control unit that performs a third operation that does not perform a registration operation while the conveyance roller is rotated forward ;
A sheet feeding apparatus comprising :
When the control unit performs the first operation or the second operation and conveys a sheet having its leading end abutting against the nip downstream, and the sheet is a sheet that easily enters the nip, the control unit A fourth operation for rotating the feeding roller and the conveying roller at the same time and rotating the conveying roller after rotating the feeding roller when the sheet is a sheet that is difficult to enter the nip. sheet feeding apparatus, characterized in that to perform. 2. The sheet feeding apparatus according to claim 1, wherein, when performing the second operation, the control unit stops the feeding roller after stopping the feeding roller. 3. An image forming apparatus comprising the sheet feeding device according to claim 1 , wherein an image is formed on a sheet fed from the sheet feeding device by a recording head.

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