JP2023086451A - Sheet transport device and image formation device - Google Patents

Abstract

To provide a sheet transport device that surely detects a paper tip of a roll and stably transports delivered paper to a paper feeding part.SOLUTION: The sheet transport device for supplying paper P from a roll Pr formed by winding sheet-like paper to a paper feeding part, includes: a sensor 93 capable of detecting a paper tip of the roll Pr; a roller member 92 disposed at a different position from the sensor 93 in a circumferential direction of the roll Pr; and a guide member 91 capable of supporting the sensor 93 and the roller member 92 so as to abut on a surface of the roll Pr. The sheet transport device controls the rotation speed of the roll Pr when supplying the paper tip to the paper feeding part in response to the sensor displacement output.SELECTED DRAWING: Figure 4

Description

The present invention relates to a sheet conveying device and an image forming apparatus.

In an image forming apparatus that uses a roll of sheet paper (roll paper), the user manually inserts the leading edge of the paper into the paper feed unit, and then the device detects the leading edge of the paper and then feeds the paper. A sheet transport device with a paper mechanism is already known.
In the conventional paper feeding operation, it takes time and effort to manually insert the leading edge of the roll paper, and depending on the insertion method, the paper may be inserted obliquely, which causes skew and leads to a service call.

In order to address such a problem, Patent Document 1 discloses that a roll is rotated in a winding direction to peel off the paper, and the leading end of the peeled paper is detected by a sensor (a sensor whose output value changes according to the distance to the paper). is disclosed.

However, in the apparatus of Patent Document 1, since the peeling state changes depending on the thickness, stiffness, and curling state of the paper, the output of the sensor may become unstable, and there is a problem that it is difficult to reliably detect the leading edge of the paper.

On the other hand, it is required to stabilize the behavior of the paper when automatically conveying the fed paper to the paper feeding unit after the leading edge of the paper is detected.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a sheet conveying apparatus capable of reliably detecting the leading edge of a roll of paper and stably conveying the fed paper to a paper feeding unit.

In order to solve the above problems, a sheet conveying device of the present invention is a sheet conveying device that supplies the paper from a roll formed by winding a sheet of paper to a paper feeding unit, wherein the paper of the roll A sensor capable of detecting a leading end, a roller member arranged at a position different from the sensor in the circumferential direction of the roll, and a guide member supporting the sensor and the roller member so as to contact the surface of the roll. and controlling the rotation speed of the roll when the leading edge of the paper is fed to the paper feeding unit according to the displacement output of the sensor.

According to the present invention, it is possible to provide a sheet conveying device capable of reliably detecting the leading end of a roll of paper and stably conveying the fed paper to the paper feeding unit.

1 is a diagram showing a schematic configuration example of an image forming apparatus according to an embodiment of the present invention; FIG. 1 is a schematic cross-sectional view showing a configuration example of an image forming apparatus according to one embodiment of the present invention; FIG. It is a figure explaining the setting method of the conventional roll. 1 is a side view for explaining a main part of a configuration example of a sheet conveying device according to an embodiment of the present invention; FIG. 3 is a block diagram illustrating an example of functions of a sheet conveying device according to one embodiment of the present invention; FIG. It is a figure explaining the example of a structure of a guide member, and a sensor. FIG. 10 is a diagram for explaining an operation example of detecting the leading edge of paper on a roll; It is a figure explaining the difference by the positional relationship of a roller member and a sensor. It is a figure which shows a schematic diagram and an example of a signal waveform when a roll surface has a concave crack. FIG. 10 is an explanatory diagram showing the relationship between the position of the leading edge of the paper on the roll and the change in the sensor output signal; FIG. 4 is an explanatory diagram showing details of sensor signal changes; FIG. 5 is an explanatory diagram showing the relationship between the roll diameter and the amount of change in sensor signal; FIG. 5 is an explanatory diagram showing the relationship between the paper thickness of paper and the amount of sensor signal displacement (pulse); 6 is a flow chart illustrating an example of operation for setting rolls in the sheet conveying device according to the embodiment of the present invention; 15 is a flowchart showing a detailed flow of leading edge detection processing in the flowchart of FIG. 14; FIG. 16 is a flowchart showing the flow following FIG. 15; FIG. FIG. 17 is a diagram illustrating explanations of symbols in FIGS. 15 and 16; FIG.

A sheet conveying device and an image forming apparatus according to the present invention will be described below with reference to the drawings. In addition, the present invention is not limited to the embodiments shown below, and can be changed within the scope of those skilled in the art, such as other embodiments, additions, modifications, deletions, etc. is also included in the scope of the present invention as long as the functions and effects of the present invention are exhibited. Further, in each drawing, constituent elements and corresponding portions having the same configuration or function are denoted by the same reference numerals, and descriptions thereof are omitted.

A sheet conveying device according to the present invention feeds and supplies a sheet from a roll. A roll is formed by winding a long sheet of paper (also referred to as a “sheet”).

A configuration example of an image forming apparatus to which a sheet conveying device according to an embodiment of the present invention is applied will be described with reference to FIGS.
An image forming apparatus, which is one aspect of an embodiment of the present invention, is an inkjet printer that prints on a recording medium by ejecting ink droplets corresponding to image data. It is also possible to apply it to an electrophotographic copying machine, a printing machine, or the like.

FIG. 1 is a perspective view of a schematic configuration example of an image forming apparatus 80 according to one embodiment, and FIG. 2 is a side cross-sectional view of the image forming apparatus. explain. 1, X indicates the depth direction (front-rear direction) of the image forming apparatus 80, Y indicates the width direction (main scanning direction) of the image forming apparatus 80, and Z indicates the vertical direction.

In FIG. 1 , the image forming apparatus 80 includes an image forming section 60 and a sheet conveying section 20 . FIG. 1 shows a serial-type liquid ejection type (ink ejection type) image forming apparatus, in which a body housing 81 is arranged on a body frame 82 . The image forming apparatus 80 has a main guide rod 64 and a sub-guide rod 65 extending in a main scanning direction indicated by a double-headed arrow Y in FIG. The main guide rod 64 movably supports the carriage 66 , and the carriage 66 is provided with a connecting piece 66 a that engages with the sub-guide rod 65 to stabilize the posture of the carriage 66 .

The image forming apparatus 80 has an endless belt-like timing belt 67 arranged along the main guide rod 64 , and the timing belt 67 is stretched between the drive pulley 68 and the driven pulley 69 . The drive pulley 68 is driven to rotate by the main scanning motor 70, and the driven pulley 69 is arranged in a state of giving a predetermined tension to the timing belt 67. As shown in FIG. The driving pulley 68 is rotationally driven by the main scanning motor 70 to rotate the timing belt 67 in the main scanning direction according to the rotational direction thereof.

The carriage 66 is connected to a timing belt 67, and the timing belt 67 is rotated in the main scanning direction by a drive pulley 68, thereby reciprocating the carriage 66 along the main guide rod 64 in the main scanning direction.

In the image forming apparatus 80 , a cartridge section 71 and a maintenance mechanism section 72 are detachably housed at an end position in the main scanning direction inside a main body housing 81 . The cartridge unit 71 accommodates replaceable cartridges 73 that respectively accommodate yellow (Y), magenta (M), cyan (C), and black (K) inks. Each cartridge of the cartridge unit 71 is connected to a print head (not shown) of a corresponding color of the print head (not shown) mounted on the carriage 66 by a pipe (not shown). supply ink.

The image forming apparatus 80 moves the carriage 66 in the main scanning direction, and intermittently scans the platen (plate) 74 (see FIG. 2) in the sub-scanning direction (the arrow X direction in FIG. 1) perpendicular to the main scanning direction. An image is recorded on the paper P by ejecting ink onto the paper P conveyed to the .

The paper P is not limited to paper, and various types of paper such as film can be used. The roll formed by winding is Pr (Pa, Pb), and the core tube (core portion) of the roll Pr is Ps.

As shown in FIG. 2, the image forming apparatus 80 is provided with a chamber 75 in which a fan is arranged below a platen 74. By driving the fan, the paper P conveyed on the platen 74 is moved to the platen. It is transported while being brought into close contact with 74 .

The image forming apparatus 80 intermittently conveys the paper P in the sub-scanning direction, and while the conveyance of the paper P in the sub-scanning direction is stopped, the image forming apparatus 80 is mounted on the carriage 66 while moving the carriage 66 in the main scanning direction. An image is formed (recorded) on the roll-shaped paper P by ejecting ink onto the paper P on the platen 74 from the nozzle rows of the recording head.

The maintenance mechanism unit 72 cleans the ejection surface of the print head, caps it, ejects unnecessary ink, and the like, thereby discharging unnecessary ink from the print head and maintaining the reliability of the print head.

The image forming apparatus 80 has an encoder sheet (not shown) arranged in parallel with the timing belt 67 and the main guide rod 64 over at least the moving range of the carriage 66 . An encoder sensor for reading the encoder sheet is attached to the carriage 66 . The image forming apparatus 80 controls the movement of the carriage 66 in the main scanning direction by controlling the drive of the main scanning motor 70 based on the reading result of the encoder sheet by the encoder sensor.

Both ends of the paper P conveyed to the image forming unit 60 are detected by a reflective sensor (encoder sensor, paper edge detection sensor) mounted on the carriage 66. At that time, the paper edge detection sensor reads The size of the paper P is detected from the position in the main scanning direction.

As shown in FIGS. 1 and 2, the image forming apparatus 80 is provided with two spool bearing stands 5a and 5b in the vertical direction in FIGS. .

The paper P pulled out from the tip of the roll Pr set on the spool bearing bases 5a and 5b is, as indicated by the arrows in FIG. It is transported within the transport path 9 .
The control unit 100 controls the driving device 7 to rotate the pair of conveying rollers 6a and 6b, the registration roller 10, the registration pressure roller 17, and the like.
Below the rolls Pr (Pa, Pb), roll paper receivers 8a and 8b are provided to prevent the rolls Pr from falling.

The paper P is transported onto the platen 74 in the image forming section 60 through the transport path 9 supported by the medium transport guide members 18a, 18b and the like. When images are formed on both sides, the sheets are reversed by the reversing section 19 .

In the image forming section 60, an image is formed by ejecting liquid droplets of each color onto the paper P in accordance with image data. A cutter 76 extending in the sub-scanning direction (paper width direction) is used to cut the paper P, which is a continuous paper, to a predetermined length at the forward transport direction ejection portion of the paper P on which an image has been formed. is provided.

The cutter 76 is fixed to a wire or timing belt that is stretched between a plurality of pulleys (one of which is connected to a drive motor) to align the leading edge of the conveyed continuous paper P. , and cuts the paper P to a predetermined length by moving in the main scanning direction Y by the driving motor. The cut paper P is discharged to the discharge section.
1 and 2 show an example of the configuration of the image forming apparatus in which the rolls Pa and Pb can be set on the two spool bearing bases 5a and 5b. good.

In the above description, the configuration corresponding to the two rolls Pa and Pb was described using the identifiers a and b, but hereinafter, when not distinguished, they are described as Pr.
Further, for example, the spool bearing bases 5a, 5b, etc. will not be labeled with the identifiers a, b when they are not to be distinguished from each other.

Here, a conventional roll paper setting method will be described. FIG. 3 is a diagram for explaining a conventional roll paper setting method.
Rolls Pr (Pa, Pb) are provided with flanges (flange members) at the ends in the width direction, and the spool 1 is set thereon. The user sets the roll Pr on which the spool 1 is set to the paper feed unit receiving portion (spool bearing stand) of the device, searches for the leading edge of the paper on the roll Pr, and while maintaining the leading edge, performs the operation as shown in FIG. 3(B). While pressing with both hands, the roll Pr is rotated so that the leading edge of the paper P comes to the front. Next, the user positions the leading edge of the sheet between the guide plates G at the back of the roll Pr and inserts the roll Pr while rotating it (see FIGS. 3(C) and 3(D)). The guide plate G is made of a transparent material so that the paper can be seen, and is composed of two upper and lower plates. When the user rotates the roll paper backward so that the leading edge of the paper is at the top of the lower guide, and inserts the paper into the back of the guide, the paper is fixed inside and pulled into the device. there is

Since the guide plate into which the leading edge of the paper is inserted is located at the back of the roll Pr, it is hidden behind the roll Pr and is difficult to see. There are cases where you have to do it all over again. Moreover, if the guide plate is not transparent, it will be difficult to confirm whether the guide plate has been inserted between the two guide plates.
In addition, it is necessary to insert the leading edge of the paper of the roll Pr as evenly as possible, which requires careful work. Furthermore, if the leading edge of the paper is not inserted evenly, the paper is fed obliquely, causing skew, which may lead to redoing the operation or causing a jam.

Further, as shown in FIGS. 3(A) to 3(C), particularly in an apparatus having a two-stage roll setting section, when the roll Pa is set in the upper stage, the roll Pb is placed in the lower stage. When setting and inserting the leading end between the guide plates, since the upper roll Pa is already present, the guide plate G is more difficult to see, which increases the difficulty of setting and the risk of oblique insertion.

Therefore, the sheet conveying apparatus of the present embodiment detects the leading edge of the sheet of the roll Pr by detecting the level difference at the leading edge of the sheet with a sensor, and conveys the leading edge of the sheet to the paper feeding unit.
The paper feeding unit is means for supplying paper P to a supply destination (for example, an image forming unit of an image forming apparatus), and is composed of, for example, the transport roller pair 6 or the transport path 9 shown in FIG. .

FIG. 4 is a side view for explaining the essential part of the configuration example of the sheet conveying device according to one embodiment.
As shown in FIG. 4, the sheet conveying device of the present embodiment is a sheet conveying device that supplies paper P from a roll Pr formed by winding a sheet of paper to a paper feeding unit. A sensor 93 capable of detecting the leading end, a roller member 92 arranged at a position different from the sensor 93 in the circumferential direction of the roll Pr, and a guide member 91 supporting the sensor 93 and the roller member 92 so as to contact the surface of the roll Pr. and have.
The guide member 91 is rotatable and supports the roller member 92 and the sensor 93 so as to be able to contact and separate from the surface of the roll Pr.
In addition, it is preferable to provide the conveying roller pair 6 constituting the paper feeding section, and further to provide an entrance guide plate 95 on the upstream side in the direction in which the leading edge of the paper is supplied to the paper feeding section.

FIG. 4 shows the position when the roll Pr is set in the sheet conveying device. The roll Pr is rotatably held by a module component (not shown) with a roll center (axis) 96 as a reference.
In FIG. 4, the forward rotation indicated by arrow D2 is the direction of rotation during the feeding operation in which the roll paper Pr is fed in the conveying direction, and the reverse rotation indicated by arrow D3 is the direction of rotation during the paper leading edge detection operation. ing. Also, S indicates the paper leading end stop position.

The guide member 91 is configured to be rotatable about a rotation center 911 . Further, the guide member 91 supports the roller member 92 and the sensor 93 on the other end side of the rotation center 911 in the sheet conveying direction.
Since the guide member 91 is pressed in the direction of the roll Pr by a spring or the like, the roller member 92 and the sensor 93 are in contact with the outer circumference of the roll Pr even if the roll diameter changes. An arrow D4 indicates the rotation direction of the guide member 91 .

The guide member 91 is also a member that guides the paper P peeled off from the roll Pr to the paper feeding unit.
The guide member 91 has a region facing the roll Pr formed in a shape (for example, an arc shape) along the outer diameter of the roll so that the roll Pr is held when the roll Pr is set (so as not to fall, etc.). It is preferably shaped so as to
The guide member 91 also functions as the roll paper receiver 8 shown in FIG.
Since the guide member 91 also serves as a member for guiding the roll Pr, the number of parts can be reduced and the cost can be suppressed.
The roller member 92 and the sensor 93 are arranged so as to face the roll center (axis) 96 (to face the roll center (axis) 96) regardless of the size of the roll diameter.

The roll Pr rotates in the direction of winding the paper by the reverse rotation (CW) indicated by the arrow D3, and the leading end of the paper is detected. After the leading edge of the paper is detected, the operation is switched to forward rotation (CCW) indicated by arrow D2, and the leading edge of the paper is conveyed to the paper feeding section in the conveying direction indicated by arrow D1.

Next, control of the functions of the sheet conveying device will be described.
FIG. 5 is a functional block diagram illustrating an example of functions of the sheet conveying device according to one embodiment.
A control unit 110 controls the entire sheet conveying apparatus. FIG. 5 shows an example of functional blocks in which the control unit 110 controls the sensor 93, the operation panel 170, and the motor drive circuit units 120 and 140, and other functional blocks are omitted.
Also, the functions of the control unit 110 may be configured to be executed by the control unit 100 (see FIG. 2) that controls the entire image forming apparatus. Similarly, the operation panel 170 that receives input from the user may also be configured to function as an operation panel of the image forming apparatus.

The control unit 110 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like.
The CPU executes various programs, performs arithmetic processing, and controls the entire image processing apparatus based on control programs.
The RAM is a volatile storage medium for reading and writing information at high speed, and functions as a work area when the CPU executes programs.
The ROM is a read-only non-volatile storage medium in which various programs and control programs are stored.

The motor drive circuit unit 120 drives the motor under the control of the control unit 110 and drives the roll drive unit 130 .
The roll drive unit 130 rotates the roll in the normal direction or the reverse direction. The roll drive unit 130 uses, for example, a roll rotation motor.
The motor drive circuit unit 140 drives the motor under the control of the control unit 110 to drive the transport drive unit 150 .
The transport drive unit 150 drives the transport unit 160 .
The transport unit 160 is a transport unit that transports a sheet, and is, for example, a pair of transport rollers 6 .

6A and 6B are explanatory views showing an example of the configuration of the guide member provided in the sheet conveying apparatus of the present embodiment. FIG. 6A is a perspective view explaining an example of the guide member 91, and FIG. 6B is a sensor 93. FIG. 6C is a side view illustrating an example of an actuator and a side plate that constitute the sensor 93. FIG.
The sensor 93 is preferably arranged downstream of the roller member 92 in the direction in which the leading edge of the paper is supplied to the paper feeder.

As the sensor 93, for example, an encoder sensor in which an actuator 931 is provided with a slit 932 is used. The actuator 931 is arranged between two side plates 933 that constitute the housing of the sensor. The actuator 931 has, for example, an asymmetric shape about an axis 934 as shown in FIG. 6(C).
The sensor 93 has a light-emitting portion and a light-receiving portion (not shown). ) to detect the tip of the roll Pr.

In the configuration example shown in FIG. 6A, two roller members 92 are arranged in the width direction of the guide member 91, and the sensors 93 are arranged in the width direction of the guide member 91. is placed between
In this manner, two or more roller members 92 are arranged in the width direction of the guide member 91, and the sensor 93 is arranged between them. It is possible to prevent the output of the sensor 93 from becoming unstable due to the thickness, stiffness, and curling of the paper, and to reliably detect the leading edge of the paper.
In addition, since the roller member 92 and the sensor 93 are displaced in the circumferential direction of the roll Pr, even if there is a partial scratch or the like, the damage to both the roller member 92 and the sensor 93 is reduced. , erroneous detection is unlikely.

7A and 7B are diagrams for explaining an operation example for detecting the leading edge 97 of the paper. 8A and 8B are diagrams for explaining the difference due to the positional relationship between the roller member 92 and the sensor 93. FIG.
7A shows the state before the leading edge 97 of the paper passes through the roller member 92 and the sensor 93, and FIG. 7B shows the leading edge of the paper. FIG. 7C shows the state before the paper 97 has passed the roller member 92 and the sensor 93, and the state where the leading edge 97 of the paper has passed the sensor 93. FIG.
8A shows the case where the roller member 92 is downstream of the sensor 93 in the direction in which the leading edge of the paper is supplied to the paper feeding unit, and FIG. 8B shows the case where the roller member 92 is upstream of the sensor 93. Each case is shown. Also, FIG. 8 shows the difference in the occurrence of the paper slack 98 in the leading edge detection operation.

The sensor 93 and the roller member 92 are arranged near each other with an offset (offset in the circumferential direction of the roll). The roller member 92 can hold the leading edge of the paper (FIG. 7(A)).
As shown in FIG. 7B, when the leading edge 97 of the paper passes the roller member 92, the guide member 91 moves in the direction of arrow D6. The actuator of sensor 93 then moves in the direction of arrow D5. As shown in FIG. 7C, when the leading edge 97 of the paper passes the sensor 93, the actuator of the sensor 93 moves in the direction of arrow D7.
As a result, when the tip of the sensor 93 is in close contact with the surface of the roll Pr, it is possible to detect a portion having a step (difference in paper thickness) on the roll surface as the tip of the paper. The output (detection result) of the sensor 93 does not become unstable due to the curling state, and the sensor 93 can reliably detect the leading edge of the paper on the roll Pr.

In addition, although the roller member 92 is arranged upstream of the sensor 93 in the example of the present embodiment, detection is possible even in the reverse arrangement (FIG. 8A). However, it is preferable to dispose the roller member 92 upstream of the sensor 93 because it is possible to more reliably hold the leading end portion of the paper until just before detection.
Further, by providing two roller members 92 and arranging the sensor 93 between the two roller members 92 as shown in FIG. can be held more securely.

Furthermore, in the sheet conveying apparatus of the present embodiment, the roller member 92 and the sensor 93 are displaced in the circumferential direction of the roll Pr. and the ratio of both will decrease.
FIG. 9(A) shows a state in which the sensor 93 is in contact with a concave scratch on the roll surface.
As shown in FIG. 9(A), a concave scratch is generally larger at the tip of the sensor 93, and the edge of the scratch is not detected because it is not as sharp as the leading edge of the paper. By making the shape of the actuator of the sensor 93 larger than that of the concave scratch, such a scratch is not erroneously detected as the edge of the sheet, and detection accuracy is ensured.

FIG. 9B shows an example of signal waveforms when detecting the leading edge of the paper, and FIG. 9C shows an example of signal waveforms when detecting a convex scratch.
In the arrangement of the roller member 92 and the sensor 93 as shown in FIG. 6A, the signal waveform shown in FIG. .
On the other hand, when the surface of the roll Pr has a belt-like convex scratch or the like, the signal waveform becomes as shown in FIG. 9(C).
For this reason, the control unit 110 can distinguish between the signal waveform of normal paper leading edge detection and the signal waveform due to a convex scratch in the detection result of the sensor 93, and can prevent erroneous detection. .

As shown in FIGS. 4 to 9, the sheet conveying apparatus according to the present embodiment can detect the edge of the roll Pr without the output of the sensor becoming unstable due to the thickness, stiffness, and curling of the sheet. Accuracy is ensured.

10 to 13, the detection of the leading edge of the paper based on the sensor displacement output and the detection of the roll diameter will be described.
The conveying device according to the present invention controls the rotational speed (number of rotations) of the roll Pr when feeding the leading edge of the paper to the paper feeding unit according to the sensor displacement output.
Specifically, the sensor displacement output is used to detect the leading edge of the paper, and the roll diameter of the roll Pr is detected from the sensor displacement output per unit time. Controls the rotation speed (number of rotations) of Pr.
More specifically, the leading edge of the paper is detected by the sensor displacement output per unit time, and the size of the roll diameter of the roll Pr is detected by setting a threshold value for the sensor displacement output per unit time. The rotational speed (number of rotations) of the roll Pr when feeding the leading edge of the paper to the paper feeding unit is controlled according to the value of .

Further, the conveying device according to the present invention can detect the thickness of the paper P according to the sensor displacement output.

Furthermore, the operation of detecting the roll diameter of the roll Pr can be executed at any timing. After the roll diameter is detected, the operation of supplying the leading edge of the paper to the paper feeding unit is executed.
The current roll diameter of the roll Pr can be calculated from the roll diameter and paper thickness of the paper P detected according to the sensor displacement output per unit time, and the cumulative rotation amount of the roll Pr.

FIG. 10 is an explanatory diagram showing the relationship between the leading edge position of the roll paper and the sensor output signal change, and FIG. 11 is an explanatory diagram showing details of the sensor signal change.
As shown in FIG. 10A, before the leading edge 97 of the paper passes the roller member 92 (up to the broken line A) is "I", and before the leading edge 97 of the paper passes the roller member 92 and passes the sensor 93 (from the broken line A FIG. 10(B) shows the sensor output signals obtained when "II" is "up to the dashed line B)" and "III" is after the leading edge 97 of the paper has passed the sensor 93 (after the dashed line B).

To detect the leading edge of the paper, the roll Pr is first reversed (CW) in the D3 direction, and when the leading edge of the paper passes the roller member 92 (dashed line A), the sensor displacement output K1 per unit time and the sensor 93 A sensor displacement output K2 per unit time is detected when passing (broken line B). By detecting K1 and K2, the leading edge of the paper is detected.
After the detection of the sensor displacement output K1, it is assumed that the leading edge of the paper is detected when the sensor displacement output K2 is detected continuously within the set time (T1). be able to.
Note that T1 can be expressed by the following formula.
T1 = (Circumferential distance from roller member to sensor (mm)) ÷ (Paper edge linear velocity (mm/s)) + (Set margin)
The paper leading edge linear velocity can also be expressed as the number of motor revolutions (rotational speed).

If the leading edge of the paper is not detected during one rotation of the roll Pr, the detection accuracy can be improved by repeating the same detection operation a predetermined number of times and by enabling the number of repetitions to be set. . The flow of detection operation will be described later.

In addition, in the configuration in which two or more roller members 92 are arranged along the roll axis direction as shown in FIG. In this case, the timing at which the leading edge of the paper passes through each roller member 92 differs, which may make it difficult to detect the sensor displacement output K1.
In such a case, when the leading edge of the paper is not detected even after the detection operation is repeated a predetermined number of times, detection accuracy can be improved by detecting only the sensor displacement output K2 when the leading edge of the paper passes the sensor 93. can be done.

In addition, when the leading edge of the paper is detected only by detecting the sensor displacement output K2, after the first K2 detection, when the sensor displacement output K2 is detected again within a certain time range (T2) corresponding to the cycle of one rotation of the roll, the leading edge of the paper is detected. is detected and the number of detection operations can be arbitrarily set, the detection accuracy can be improved.

After detecting the leading edge of the paper, the leading edge of the paper is stopped at the leading edge stop position indicated by symbol S in FIG. It is possible to suppress variations in posture and stably transport paper to the paper feed unit regardless of paper conditions (curl/paper type/paper thickness).

FIG. 12 is an explanatory diagram showing the relationship between the roll diameter and the amount of sensor signal change.
FIG. 12(A) is an explanatory diagram showing the size of the roll diameter of the roll Pr, FIG. 12(B) shows changes in the sensor signal when the roll diameter is large, and FIG. 12(C) shows the roll diameter This is the change in the sensor signal when the diameter is small. FIG. 12D is a table showing an example of roll diameter detection (calculation) using a threshold value.

When the roll Pr is rotated at a constant rotational speed (number of revolutions, rpm), the movement speed (mm/s) of the leading edge of the paper differs depending on the size of the roll diameter.
As shown in FIGS. 12B and 12C, the amount of change in the sensor displacement outputs K1 and K2 per unit time varies depending on the moving speed (mm/s) of the leading edge of the paper. Therefore, by providing a threshold for the sensor displacement output, it is possible to detect the size of the roll diameter.
As shown in FIG. 12(D), the value x of the roll diameter can be calculated by Equation 1 or Equation 2 below.
x=(K1+K2)/2 Expression 1
x=K2 Expression 2
Although the size of the diameter can be distinguished by providing one threshold value, a plurality of threshold values can also be provided. By providing a plurality of thresholds, the roll diameter can be distinguished in more detail.
For example, the value of the obtained roll diameter x can be small when x<1, medium when 1≤x<2, and large when 2≤x.

According to the obtained value of the roll diameter, it is possible to control the transport speed at which the paper is transported to the paper feeding unit after the operation of detecting the leading edge of the paper, that is, the rotation speed (number of rotations) of the roll Pr.
By keeping the paper transport speed constant regardless of the roll diameter, the paper can be stably transported.

In addition, the roll Pr is rewound (CW) for each print job in the image forming unit, the roll diameter is detected, and the roll is rotated forward (CCW) again to carry out the paper conveying operation. Amount can be detected.

FIG. 13 is an explanatory diagram showing the relationship between the paper thickness and the sensor signal displacement amount (pulse).
Since the sensor signal displacement amount (pulse) changes depending on the paper thickness, the paper thickness can be detected by setting a threshold for the sensor displacement output.
As shown in FIG. 13, for example, thin paper can be used when y<0.6, plain paper can be used when 0.6≦y<0.9, and thick paper can be used when 0.9≦y.
The paper thickness setting is necessary for setting the printing conditions in the image forming unit, so if it can be detected automatically, users will be able to save the trouble of manually setting the paper thickness from the control panel. .

Further, the current roll diameter of the roll Pr can be calculated using the roll diameter and paper thickness of the paper P detected according to the sensor displacement output per unit time, and the cumulative rotation amount of the roll Pr.
The control unit counts the amount of rotation of the roll Pr, acquires the integrated amount of rotation (total amount of rotation), and uses the value of the roll diameter and the paper thickness obtained during the operation of detecting the leading edge of the paper to calculate, for example, the following formula: Calculate the roll diameter.
(Current roll diameter) = (roll diameter x) - (paper thickness) x 2 - (roll cumulative rotation amount)
Note that the roll diameter x is a value obtained by (K1+K2)/2.

14 to 16 are flowcharts for explaining an operation example of setting the roll Pr in the sheet conveying device according to one embodiment of the present invention. Note that FIG. 17 shows an explanation of the symbols in the flow.
FIG. 14 is a flow chart showing the overall flow. When the control unit 110 detects that the roll Pr is set in the sheet conveying device (detected by the detection result of the sensor 93, for example) (S001), the motor driving circuit 120 to control the roll drive unit 130 to reverse the roll Pr.
The roll rotation motor (roll driving unit 130) rotates the roll Pr in the winding direction by reverse operation (S002), and the sensor 93 starts the leading edge detection operation (S003).

It is determined whether the detection of the leading edge is completed (S004), and if the operation of detecting the leading edge of the sheet is to be performed, the flow of FIG. A detailed flow of the paper leading edge detection operation is shown in FIGS. 15 and 16, and is connected by a connector B to return to this flow.
When the leading end of the paper is detected, the control unit 110 controls the motor drive circuit unit 120 to stop the roll rotation motor at the leading end stop position of the paper (S005). (S006). The rotation speed (number of rotations) of the roll rotation motor in step S006 is variable according to the roll diameter detected in the paper leading edge detection operation. A paper conveying operation is performed to convey the paper P drawn out from the roll Pr rotating at the controlled rotational speed to the paper feeding unit (S007). The motor drive circuit unit 140 rotates the transport unit 160 to transport the paper into the apparatus.

FIG. 15 shows a detailed flow of the paper leading edge detection operation connected by the connector A from step S004 in FIG.
First, starting from the paper leading edge detection count N=0 (S101), it is determined whether or not the sensor displacement output K1 has been detected (S102). After detecting K1, it is determined whether K2 is detected within T1 (S103). "T1" is a time obtained by adding a set margin to the movement time of the leading edge of the paper, which is calculated based on the number of motor revolutions and the distance from the roller member to the sensor.
When K2 is detected, the roll diameter is detected from K1 and K2 (S104). Then, the paper leading edge detection count N is increased by one (S105).

Next, it is determined whether or not the number of times N of sheet leading edge detections is greater than or equal to the set value a (S106). "a" is a reference value for the number of detections (how many detections are required to determine that the leading edge of the sheet has been successfully detected).
If N is greater than or equal to a, the detection of the leading edge of the paper is successful (S107).
The roll diameter is calculated based on the values of the sensor displacement outputs K1 and K2, and the size of the roll diameter is determined from a preset threshold value (S108). The subsequent flow is connected to step S005 in FIG. The rotation speed of the roll when feeding the leading edge of the paper to the paper feeding unit is controlled in step S006 of FIG. 14 according to the value of the roll diameter obtained in step S108.

On the other hand, if N is less than a in step S106, it is determined whether K1 is detected again within T2 after detecting K1 (S109). "T2" is the time obtained by adding a set margin to the time for one rotation of the roll calculated based on the number of rotations of the motor.
If K1 is detected, then it is determined whether K2 is detected within T1 (S110). When K2 is detected, the number of times the leading edge of the sheet is detected is incremented by one (S105).

If K1 is not detected in step S109, if K2 is not detected in step S110, and if K2 is not detected in step S103, it is determined whether the roll rotation is R times or more (S111). . “R” is a set value of the number of roll rotations (how many times the roll is rotated until the leading edge of the paper is detected).
If the cumulative number of rotations is less than R times, the process returns to the flow from step S102. On the other hand, when the cumulative number of rotations is R times or more, the flow of FIG.

FIG. 16 shows a detailed flow of the operation of detecting the leading edge of the sheet connected by the connector E from step S111 of FIG.
First, the process starts again from the tip detection count N=0 (S201), and it is determined whether or not the sensor displacement output K2 has been detected (S202). When K2 is detected, the roll diameter is detected from K2 (S203). Further, when K2 is detected, the paper leading edge detection count N is incremented by one (S204).

Next, it is determined whether or not the number of times N of paper leading edge detections is greater than or equal to the set value a (S205). "a" is a reference value for the number of detections (how many detections are required to determine that the leading edge of the sheet has been successfully detected).
If N is greater than or equal to a, it is assumed that the leading edge of the paper has been successfully detected (S206).
A roll diameter is calculated based on the value of the sensor displacement output K2, and the roll diameter is determined from a preset threshold value (S207). The subsequent flow is connected to step S005 in FIG. The rotation speed of the roll when feeding the leading edge of the paper to the paper feeding unit is controlled in step S006 of FIG. 14 according to the value of the roll diameter obtained in step S206.

On the other hand, if N is less than a in step S204, it is determined whether K2 is detected again within T2 after K2 is detected (S208). "T2" is the time obtained by adding a set margin to the time for one rotation of the roll calculated based on the number of rotations of the motor. If K2 is detected, the number of times the leading edge of the paper is detected is incremented by one (S204), and the flow returns to the subsequent steps.

If K2 is not detected in step S208 and if K2 is not detected in step S202, it is determined whether the roll rotation is R times or more (S209). “R” is a set value of the number of roll rotations (how many times the roll is rotated until the leading edge of the paper is detected).
If the cumulative number of rotations is less than R times, the process returns to the flow from step S202.
On the other hand, if the accumulated number of rotations is equal to or greater than R times, it is determined that the detection of the leading edge of the paper has failed, and the roll rotation motor is stopped (S210).

As described above, by using the sheet conveying device according to the present invention, in an image forming apparatus that feeds roll-shaped paper, simply by setting the roll by the user, the leading edge of the paper can be automatically detected and detected automatically. , the fed paper can be stably conveyed to the paper feeding unit.

6 transport roller pair 80 image forming device 90 sheet transport device 91 guide member 92 roller member 93 sensor 95 entrance guide plate 110 control unit 911 rotation center Pr (Pa, Pb) roll P paper

JP 2018-150107 A

Claims (11)

A sheet conveying device for supplying a sheet of paper to a paper feeding unit from a roll formed by winding a sheet of paper,
a sensor capable of detecting the leading edge of the paper on the roll;
a roller member arranged at a position different from the sensor in the circumferential direction of the roll;
a guide member that supports the sensor and the roller member so as to contact the surface of the roll,
A sheet conveying apparatus, wherein the rotation speed of the roll is controlled when the leading edge of the sheet is fed to the sheet feeder according to the sensor displacement output. Detecting the leading edge of the paper from the sensor displacement output and detecting the roll diameter of the roll from the sensor displacement output per unit time,
2. The sheet conveying apparatus according to claim 1, wherein the rotational speed of said roll when feeding said leading edge of said sheet to said paper feeding unit is controlled in accordance with the value of said roll diameter. 3. The sheet conveying apparatus according to claim 1, wherein the sheet thickness of the sheet is detected according to the sensor displacement output. 4. The sheet according to any one of claims 1 to 3, wherein the operation of detecting the roll diameter of the roll is performed at an arbitrary timing, and then the operation of supplying the leading end of the sheet to the paper feeding unit is performed. Conveyor. The current roll diameter of the roll is calculated using the roll diameter and the paper thickness of the paper detected according to the sensor displacement output per unit time, and the cumulative rotation amount of the roll. The sheet conveying device according to claim 3 or 4. 6. The sheet conveying apparatus according to claim 1, wherein the sensor is arranged downstream of the roller member in a direction in which the leading edge of the sheet is supplied to the sheet feeder. 7. The sheet conveying apparatus according to claim 1, wherein said sensor comprises an encoder sensor. 8. The sheet conveying apparatus according to claim 1, wherein the guide member guides the sheet separated from the roll to the sheet feeder. 9. The sheet conveying apparatus according to claim 1, further comprising an entrance guide plate on the upstream side in the direction in which the leading edge of the sheet is supplied to the sheet feeding section. Two or more roller members are arranged in the width direction of the guide member,
10. The sheet conveying apparatus according to claim 1, wherein the sensor is arranged between one roller member and another roller member in the width direction of the guide member. An image forming apparatus comprising the sheet conveying device according to any one of claims 1 to 10.

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