JP2000118801A - Sheet conveyer device and image forming device furnished with sheet conveyer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct the skew of various sorts of sheets, by forming them in an adequate bending condition respectively, in a sheet conveyer device. SOLUTION: This sheet conveyer device 11 is furnished with a conveying roller 105 which carries a sheet to abut the tip of the sheet to two nip parts of a couples of resist rollers 106 in the condition of stopping the rotation, and bends the sheet to correct the skew of the sheet; and a control means to control the timings of the rotation and the stopping of the resist roller couples 106 and the conveying roller 105, so as to change the bending degree of the sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device for conveying a sheet, and an image forming apparatus equipped with the sheet conveying device, such as a copying machine, a facsimile or a printer.

[0002]

2. Description of the Related Art FIG. 12 shows a conventional sheet conveying apparatus.

The sheet conveying device is incorporated in a copying machine which is an example of an image forming apparatus, and conveys the sheet S sent from the cassettes 1a and 1b to the photosensitive drum 112. The sheet includes paper, a thin resin sheet that is a substitute for paper, and the like.

In FIG. 12, reference numerals 1a and 1b denote cassettes in which different types of sheets can be set. Reference numeral 304 denotes a feeding path from a lower cassette (not shown). Reference numeral 121 denotes a sheet reversing conveyance path for performing double-sided or multiple image formation. Reference numeral 105 denotes a transport roller. Reference numeral 106 denotes a registration roller. The registration roller 106 is a sheet from any sheet path, in any type (thickness, size, hardness, etc.) or in any state (curl direction, curl amount, degree of moisture absorption due to environment, etc.) Also, the feed roller 105 rotates the feed roller 105 in a state where the leading edge of the sheet is brought into contact with the nip, thereby forming a constant loop amount 300 in the sheet path 301 to correct the skew of the leading edge of the sheet. I have.

[0005]

However, in the conventional sheet conveying apparatus, the loop amount in the registration roller 106 is constant regardless of the type and state of the sheet. Could not be corrected. Conversely, if the loop is too large, the seat will buckle, or in the worst case jam,
There is also a risk that the direction and force of pushing into the registration roller 106 will be inappropriate, making it impossible to correct skew accurately.

Further, a copying machine (image forming apparatus) equipped with the above-mentioned conventional sheet conveying device forms an image on a sheet whose skew cannot be corrected accurately, and cannot form an accurate image. There was fear.

A first object of the present invention is to abut the leading edge of the sheet against the nip of the pair of rollers for any type of sheet to form an appropriate amount of loop to reliably correct skew. It is an object of the present invention to provide a sheet conveying device capable of performing the above.

A second object of the present invention is to irrespective of the state of a sheet, abutting the leading end of the sheet against the nip of a pair of rollers to form an appropriate amount of loop to reliably correct skew. It is an object of the present invention to provide a sheet conveying device capable of performing the above.

A third object of the present invention is to provide an image forming apparatus capable of accurately forming an image.

[0010]

The above object is achieved by the following sheet conveying apparatus.

A conveying roller that conveys the sheet, abuts the leading end of the sheet against the nip portion of the registration roller pair that is not rotating, curls the sheet, and corrects the skew of the sheet; Control means for controlling the timing of rotation and stop of the registration roller pair and the conveyance roller in accordance with the type information, and changing the degree of curvature of the sheet.

There are a plurality of types of the sheets, and the control means reads out the degree of curvature of the sheet corresponding to the type of the sheet stored in advance based on the input type information of the sheet, and The timing for stopping the rotation of the rollers is controlled.

The sheet type information is input by type input means for inputting the type of the sheet.

The type input means is an operation unit provided on the apparatus main body for inputting by a user.

The sheets are stacked on sheet stacking means which is detachable from the apparatus main body, and the type input means is provided on a size sensor provided on one of the apparatus main body and the sheet stacking means and on the other. And an operating body for operating the size sensor when the sheet stacking means is mounted on the apparatus main body.

A conveying roller for conveying the sheet, abutting the leading end of the sheet against the nip portion of the registration roller pair that is not rotating, and curving the sheet to correct skew of the sheet; Control means for controlling the timing of rotation and stop of the registration roller pair and the conveyance roller in accordance with the state information, and changing the degree of curvature of the sheet.

There are a plurality of states of the sheet, and the control means reads out a degree of curvature of the sheet corresponding to the type of the sheet stored in advance based on the input state information of the sheet, and The timing for stopping the rotation of the transport roller is controlled.

The sheet status information is information from a humidity sensor.

The above problem is solved by the following image forming apparatus.

The image forming apparatus includes a sheet conveying device according to any one of claims 1 to 8, and an image forming unit that forms an image on a sheet sent from the sheet conveying device.

(Operation) The control means stops the rotation of the registration roller pair and rotates the conveyance roller to convey the sheet, and causes the leading end of the sheet to abut the nip portion of the registration roller pair. Then, the rotation of the transport roller is stopped based on the input sheet type information. The slower the time when the rotation of the conveyance roller is stopped, the longer the distance the conveyance roller conveys the sheet, and the larger the sheet is curved.

Therefore, by stopping the rotation of the conveying roller in accordance with the input sheet type information, the sheet can be bent to an optimum state for correcting skew according to the type of sheet.

There are a plurality of sheet types, and the control means reads out the degree of sheet curvature corresponding to the sheet type stored in advance based on the input sheet type information, and stops the rotation of the transport roller. Control the time.

The sheet type information is stored in an operation section of the apparatus main body,
Alternatively, the input is performed by a size sensor that is operated by an operating body when the cassette is mounted on the apparatus main body.

Similarly, when the input information is the sheet state information, the rotation of the conveying roller is stopped according to the sheet state information, thereby correcting the skew according to the sheet state. It can be curved to an optimum state.

There are a plurality of sheet states, and the control means reads out the degree of sheet curvature corresponding to the sheet state stored in advance based on the inputted sheet state information, and stops the rotation of the transport roller. Control the time.

Sheet status information is input by a humidity sensor.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

First, a copying machine, which is an example of an image forming apparatus in which a sheet conveying apparatus according to a first embodiment of the present invention described later is incorporated, will be described with reference to FIG. The copying machine incorporates sheet conveying devices according to second and third embodiments to be described later, but illustration thereof is omitted. Further, the sheet conveying apparatuses according to the first to third embodiments of the present invention can be incorporated not only in a copying machine but also in a facsimile, a printer, and the like, but the drawings are omitted.

The same portions as those shown in FIG. 12 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1, an image reading section B for reading image information of a document is disposed at an upper portion of the image forming apparatus main body A, and an image for recording an image on a sheet S according to the image information is provided below the image reading section B. Forming part C is arranged.

Below the image forming section C, cassettes 1a and 1b for accommodating sheets S such as paper, plain paper such as synthetic resin sheets for paper, envelopes, and OHP sheets are provided so as to be drawn out and accommodated. I have.

Sheets S stored in cassettes 1a and 1b
Are selectively fed out by a pickup roller 3 serving as sheet feeding means in response to an instruction from a user or the like, and separated one by one by a pair of retard rollers 4 and 5 serving as separating means. The sheet is fed to the image forming section C to a position facing the photosensitive drum 112 through 302 and 302.

Here, when the copying machine main body A is in the copying mode, the scanning optical systems 201, 204 and 205 are driven, and
Image information of a document set on the document table 202 is read by the image reading unit 206.

Then, based on the image information read by the image reading means 206, the laser scanner 111 emits a laser beam L, and the surface thereof is uniformly charged by the charging roller 130. The surface of the rotating photosensitive drum 112 is scanned via a reflection mirror 131 to form an electrostatic latent image on the photosensitive drum 112. Toner is supplied to the electrostatic latent image from the developing device 114 to form a toner image, and the electrostatic latent image is visualized.

As described above, the cassettes 1a, 1a
In a state in which the leading end of the sheet S fed from the sheet b comes into contact with the nip of the pair of registration rollers 106, 106, the sheet S is formed in a loop with the conveyance roller 105, and then synchronized with the rotation of the photosensitive drum 112. Then, the toner image formed on the photosensitive drum 112 is transferred to a sheet by being conveyed between the photosensitive drum 112 and the transfer roller 115 disposed at a position facing the photosensitive drum 112.

The sheet S to which the image has been transferred is conveyed by the conveyor belt 117 and sent to the fixing device 118, where it is heated and pressed to fix the toner image.

When the copying machine main body A is in the print mode or the facsimile mode, the laser scanner 111 emits the laser beam L based on the image information sent from the external computer or the other party's facsimile machine, and performs the same operation as described above. Thus, a toner image is formed on the sheet S and fixed.

Then, the sheet S fixed by the fixing device 118 is discharged onto a discharge sheet tray 120 via a sheet discharge roller 119.

(First Embodiment) Next, a description will be given with reference to FIG. 2 which is an enlarged sectional view of the sheet conveying apparatus 11 of the first embodiment.

The sheet conveying device 11 determines whether or not the type of the sheet S is a predetermined first type. According to the determination result, the leading end of the sheet S is set to the registration roller pair 106,
A control system 12 (FIG. 3) for changing the loop amount in a state where the loop 106 abuts on the nip is provided.

In the sheet conveying apparatus 11, an envelope, a postcard, a cardboard, an OHP, etc., which are relatively stiff sheets, are set as the first type of sheet S.
Is described as an example.

The envelope S1 set in the cassette 1b is
The processing is performed by the control system 12 shown in FIG. 3 according to the flowchart shown in FIG. First, as shown in FIG.
f is housed in the cassette 1b such that the flap portion f1 of the envelope Sf is at the top and at the leading end in the transport direction.
Then, by inserting the cassette 1b into the apparatus main body A, the size frame 41 of the cassette 1b is detected by the size sensor 42 as a detecting means provided in the apparatus main body A, and the type of the sheet S stored in the cassette 1b is determined. The envelope 44 is recognized by the CPU 44 of the apparatus main assembly A (step 11 in FIG. 4). Then, the user gives an instruction to send the envelope from the operation unit 45 shown in FIG. 3, and this instruction is sent to the CPU 46 (step 12). The operation unit 45 is provided on the upper part of the copying machine main body A of FIG.

After receiving the instruction, the CPU 44 sends a signal to the clutch 307 at a set timing to stop driving the transport roller 105 after the leading end of the envelope Sf hits the nip of the registration roller pair 106, thereby stopping the envelope Sf. An appropriate pre-resist loop amount 305 is formed (step 13). The state in which the leading end of the sheet S abuts on the nip of the registration roller pair 106 is detected by a sheet leading end detection sensor 43 disposed near the nip. Then, by driving the registration roller 106 in accordance with the timing of the image on the photosensitive drum 112,
The skew correction of the envelope Sf is reliably performed, and the image is properly formed on the envelope Sf without skew. Further, since the loop amount is appropriate, the envelope Sf is smoothly transported without buckling or jamming.

Next, the user sets and feeds, as the second type of sheet, plain paper S2 (paper of about 60 g to about 90 g / square m), whose sheet is weaker than the envelope Sf, as a second type of sheet in the cassette 1a. Also in this case, the plain paper S2 is transported after forming an appropriate second pre-registration loop amount 306.
Skew correction is performed reliably, and there is no occurrence of buckling or jam, and the paper is smoothly transported.

According to the experiment, the loop amount 30 of the plain paper S2 was
The suitable loop amount 305 of the envelope Sf for the No. 6 is about 3 mm.
When the distance is reduced by about 7 mm, the skew correction and the conveyance of the envelope Sf can be facilitated.

In the above description, the type of the sheet S is detected by the detecting means including the size frame 41 of the cassette 2a and the size sensor 42 of the apparatus main body A, and the detected value is compared with a predetermined condition. Although the configuration for determining whether or not the type of the sheet S is the first type is described above, the present invention is not limited to this. For example, the operation unit 45 as an input unit may be used. , The type of the sheet S may be input, and the input value may be compared with a predetermined condition to determine whether the type of the sheet S is the predetermined first type. In this case, the operation unit 45
It is possible to input the type of sheet S for each cassette from, for example, when the user instructs the sheet supply from the cassette containing the first type of sheet S, the above-described envelope Sf and Similarly, the CPU 44 controls the conveyance. Even with this configuration, the supported sheet is smoothly conveyed without buckling or jamming.

Although the sheet conveying apparatus according to the first embodiment has been described for two types of sheets, the present invention is not limited to this. For three or more types of sheets, an appropriate loop amount is set for each type. By doing so, it is possible to reliably perform skew correction and excellent feeding of any type of sheet.

Accordingly, the transport device has the effect of greatly expanding the types of sheets that can be transported.

(Second Embodiment) Next, a sheet conveying apparatus 13 according to a second embodiment will be described with reference to FIGS. The sheet conveying device 13 of the second embodiment exemplifies a case where a postcard S3, which is also a relatively stiff sheet, is set and fed as a first type of sheet on the multi-feed tray 46.

When the postcard S3 is set on the multi-feed tray 46, the processing is performed by the control system 14 shown in FIG. 7 according to the flowchart shown in FIG. First, the multi-feed tray 46 will be described with reference to FIGS. As shown in the figure, the multi-feed tray 46 includes side regulating plates 47a and 47b for regulating an end in a width direction orthogonal to the conveying direction of the set sheet S.
7a and 47b have rack gears 48a and 48b, respectively. The rack gears 47a and 48b mesh with the pinion gear 49 at the center in the length direction. A rotary encoder 50 is provided coaxially with the pinion gear 49 as detection means for detecting the width of the sheet S.
When the side regulating plates 47a and 47b are moved according to the end of the sheet S set on the multi-feed tray 46,
The pinion gear 49 rotates, and the rotary encoder 50 provided on the same axis also rotates. Thereby, the length in the width direction of the sheet S is detected.

The multi-sheet supply tray 46 includes:
A trailing edge regulating plate 53 for regulating the trailing edge of the set sheet S in the transport direction is provided movably in the direction of arrow a along the elongated hole 54 formed in the tray 46. On the back side of the tray 46, a resistance sensor 56 is provided along the long hole 54 as detecting means for detecting the length of the sheet S. The rear end regulating plate 53 has a leg 55 attached to its back.
Move while making contact with the sensor 56.

Accordingly, when the rear end regulating plate 53 is moved in accordance with the rear end of the sheet S set on the multi-sheet supply tray 46, the length of the sheet in the conveying direction is detected.

Next, the operation of the control system 44 shown in FIG. 7 will be described in accordance with the flowchart shown in FIG. The side regulating plates 47a and 47b and the trailing edge regulating plate 53 regulate the position of both sides in the width direction of the sheet and the trailing edge.

When feed from the multi-feed tray 46 is instructed by the operation unit 45, the rotary encoder 50 reads between the side regulating plates 47a and 47b (step 2).
1), the CPU 44 recognizes the length of the sheet S in the width direction. The position of the trailing edge regulating plate 53 is read by the resistance sensor 56 (step 22), and the CPU 44 recognizes the length of the sheet S in the transport direction.

Next, the detected value (sheet size) and the CPU
The size is compared with the size of the postcard registered in advance in step 44 (step 23), and it is determined whether or not the sheet S is a postcard.

Then, the feeding of the sheet S by the feeding roller 52 is started (step 24). Here, if the sheet S is a postcard, the CPU 44 sends a signal to the clutch 51 at a set timing to stop driving the feeding roller 52, thereby forming a pre-registration loop 310 suitable for a postcard. (Step 25). If the sheet S has a size other than the postcard, the sheet S is also formed with an appropriate loop 311 and fed. Thus, the sheet conveying apparatus can perform skew correction reliably for any sheet, and can perform smooth feeding without buckling or jam.

As means for automatically detecting the type of the sheet, a sheet thickness detecting means is provided near the feeding roller 52, and the detected value of the detecting means is compared with a predetermined condition. The same effect can be obtained by the method of determining the type of sheet.

According to the second embodiment as described above,
In contrast to the first embodiment, the type of sheet set
Since the apparatus can automatically detect the operation without the user's operation and input, there is a further advantage that the operation operation of the user is simplified.

(Third Embodiment) A sheet conveying device 15 according to a third embodiment will be described with reference to FIGS.

The sheet conveying device 15 determines the moisture absorption state of the sheet, particularly when the sheet is paper, because the stiffness tends to change due to moisture absorption as a method of changing the pre-registration loop amount according to the state of the sheet. A case will be exemplified.

In FIG. 1, a humidity sensor 320 is provided on the upper portion of the multi-tray 46 in FIG. (A state of moisture absorption of the sheet).

FIG. 11 is an enlarged cross-sectional view of the sheet conveying device 15 according to the third embodiment. Plain paper (about 64 g paper) is set as a sheet S in the multi-sheet supply tray 46.

In the sheet conveying device 15, the CPU determines whether the detected value of the environmental humidity from the humidity sensor 320 (see FIG. 1) provided in the main body A is smaller than the humidity registered in advance in a CPU (not shown). , If small, loop amount 31
2. When the sheet is large, the loop amount 313 and the appropriate loop amount are formed and fed, so that the skew correction can be reliably performed in any moisture absorbing state of the sheet, and smooth feeding without jams or the like is performed. It can be carried out. In particular, it is extremely effective when used in an environment where the humidity varies greatly depending on the season, such as in Japan.

Also, since the magnitude of the curl amount in the state of the sheet also affects the stiffness of the sheet, a curl amount detecting means is provided near the feeding roller, and the detected value is compared with a predetermined condition. Thus, a similar advantage can be obtained by a method of forming an appropriate loop amount.

[0066]

As described above, according to the sheet conveying apparatus of the present invention, a sheet having a predetermined type, for example, a first type (envelope, postcard, OHP,
Whether it is a sheet of relatively strong stiffness such as thick paper) or a second type (a sheet of relatively stiffness such as plain paper), the optimum curvature for correcting skew for each sheet type Since the sheet can be in the state, the skew of the sheet can be reliably corrected, and the sheet can be smoothly conveyed while preventing the sheet from buckling or jamming.

In addition, the sheet conveying apparatus of the present invention has an optimum curved state for correcting skew for each sheet state, regardless of the state of the sheet (for example, the moisture absorption state or the amount of curl). Therefore, it is possible to reliably correct the skew of the sheet, prevent the buckling of the sheet, and prevent the occurrence of a jam, thereby smoothly conveying the sheet.

Further, since the image forming apparatus of the present invention is provided with the above-mentioned sheet conveying device, an image can be surely formed on a sheet fed smoothly.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an image forming apparatus provided with a sheet conveying device according to an embodiment of the present invention.

FIG. 2 is a front sectional view of the sheet conveying apparatus according to the first embodiment of the present invention.

FIG. 3 is a block diagram of a control system of the sheet conveying apparatus according to the first embodiment of the present invention.

FIG. 4 is a flowchart illustrating an operation sequence of the sheet conveying apparatus by the control system of FIG. 3;

FIG. 5 is a perspective view of a cassette of the image forming apparatus.

FIG. 6 is a front sectional view of a sheet conveying apparatus according to a second embodiment of the present invention.

FIG. 7 is a block diagram of a control system of a sheet conveying apparatus according to a second embodiment of the present invention.

FIG. 8 is a flowchart illustrating an operation sequence of the sheet conveying apparatus by the control system of FIG. 7;

FIG. 9 is a plan view of a multi-sheet supply tray.

FIG. 10 is an exploded perspective view of the multi-sheet supply tray as viewed from below.

FIG. 11 is a front sectional view of a sheet conveying apparatus according to a third embodiment of the present invention.

FIG. 12 is a front sectional view of a conventional sheet conveying apparatus.

[Explanation of symbols]

 Reference Signs List A Image forming apparatus main body B Image reading section C Image forming section S Sheet S3 Postcard Sf Envelope 1a Cassette 1b Cassette 11 Sheet transport device 12 Control system (control means) 13 Sheet transport device 14 Control system (control means) 15 Sheet transport device 41 Size frame (type input means, operating body) 42 Size sensor (type input means, operating body) 43 Sheet leading edge sensor 44 CPU 45 Operation unit (type input means) 46 Multi-sheet supply tray 51 Clutch 105 Transport roller 106 Registration roller 112 Photosensitive Body drum (image forming unit) 114 Developing device (image forming unit) 115 transfer roller 118 fixing device 119 sheet discharge roller 120 discharge sheet tray 121 sheet supply conveyance path 300 pre-registration loop 305 pre-registration loop 306 pre-registration loop 310 Gist front loop 311 pre-registration loop 312 pre-registration loop 313 pre-registration loop 320 temperature sensor (state input means)

Claims (9)

[Claims] A conveying roller that conveys the sheet, abuts the leading end of the sheet against a nip portion of a registration roller pair that is not rotating, curls the sheet, and corrects the skew of the sheet. Control means for controlling the timing of rotation and stop of the registration roller pair and the transport roller according to the sheet type information, and changing the degree of curvature of the sheet,
A sheet conveying device comprising: 2. The method according to claim 2, wherein the sheet includes a plurality of types, and the control unit reads out a degree of curvature of the sheet corresponding to the type of the sheet stored in advance based on the input type information of the sheet. The sheet conveying apparatus according to claim 1, wherein a timing of stopping the rotation of the conveying roller is controlled. 3. The sheet conveying apparatus according to claim 1, wherein the type information of the sheet is input by type input means for inputting the type of the sheet. 4. The sheet conveying apparatus according to claim 3, wherein the type input unit is an operation unit provided on the apparatus main body for inputting by a user. 5. The apparatus according to claim 1, wherein the sheet is stacked on a sheet stacking unit detachable from the apparatus main body, and the type input unit includes a size sensor provided on one of the apparatus main body and the sheet stacking unit, and a type sensor on the other side. The sheet conveying device according to claim 3, further comprising: an operating member provided to operate the size sensor when the sheet stacking unit is mounted on the apparatus main body. 6. A conveying roller that conveys a sheet, abuts the leading end of the sheet against a nip portion of a registration roller pair that is not rotating, curls the sheet, and corrects skew of the sheet. Control means for controlling the timing of rotation and stop of the registration roller pair and the conveyance roller according to the state information of the sheet, and changing the degree of curvature of the sheet,
A sheet conveying device comprising: 7. There are a plurality of states of the sheet, and the control means performs the processing based on the inputted state information of the sheet.
7. The sheet conveying apparatus according to claim 6, wherein a degree of curving of the sheet corresponding to the type of the sheet stored in advance is read out, and a timing of stopping the rotation of the conveying roller is controlled. 8. The sheet conveying apparatus according to claim 6, wherein the state information of the sheet is information from a humidity sensor. 9. An image, comprising: the sheet conveying device according to claim 1; and an image forming unit that forms an image on a sheet sent from the sheet conveying device. Forming equipment.