JPH07315633A - Paper sheet carrier - Google Patents

Abstract

PURPOSE:To reduce the carrying resistance of a paper sheet in a curved section and to obtain nipping pressure suited to the thickness of the paper sheet by providing a curved guide plate for forming the outer peripheral guide face of a curved carrier path so as to be oscillatable centering around a shaft near the head in a carrying direction, and energizing the curved plate toward an inner periphery. CONSTITUTION:In the case where a thin paper sheet 2 (shown by a dotted line) is in passing, force for energizing a curved guide plate 11 in a direction designated with the arrow A does not exist or is weak. Thus the curved guide plate 11 is energized in a direction designated with the arrow B by the tension of a tension coil spring 13 to form a curved carrier path having a large curvature. During the passing of a thick paper sheet 2 (shown by a solid line), the toughness or restoring force of the paper sheet 2 surpasses the force of the tension coil spring 13, and the curved guide plate 11 therefore rotates in a direction designated with the arrow A to reduce the curvature of the curved carrier path 10. Since the frictional resistance of the paper sheet 2 passing through the curved carrier path 10 is therefore reduced, even if nipping pressure between skew rolls 8b, 8c is small, the smooth carrying of the paper sheet can be carried out.

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, and more particularly to a sheet conveying device suitable for forming an optimum conveying state according to the thickness of a sheet to be conveyed.

[0002]

2. Description of the Related Art In a sheet conveying device such as a printer or a copying machine, a sheet is conveyed to a next process by a roll provided in a conveying path. The rolls include a transport roll that simply sends the paper to the next step and a roll that also serves as a positioning (so-called skew roll) that obliquely feeds the paper and presses it against the guide side plate. The guide side plate is a guide unit that serves as a reference for aligning a sheet with a reference position in a direction orthogonal to the sheet conveying direction. A conveying device using such a conveying roll and a skew roll is disclosed in, for example, Japanese Utility Model Laid-Open No. 1-166654.

[0003]

The above-mentioned transport device has the following problems. In a recording device such as a printer or a copying machine in which the transport device is incorporated, a complicated transport path in which a curved portion and a straight portion are combined is formed in order to downsize the printer and enable double-sided printing on paper. The skew rolls are arranged on a straight conveying path for aligning the sheets, that is, for performing an aligning operation to a predetermined position. In many cases, a curved conveying path having a large curvature is provided before and after this straight conveying path.

Therefore, in the straight conveying path provided with the skew roll, the sheet is received from the curved conveying path in the preceding stage,
In order to discharge the sheet to the curved conveying path in the subsequent stage, it is necessary to set the sandwiching strength of the skew roll (hereinafter referred to as “nip pressure”) to be high to increase the conveying force. In particular, when transporting thick paper such as postcards, the resistance at the curved portion becomes large, so that the nip pressure needs to be further increased. However, if the nip pressure is set to be high, the paper may be scratched or buckling may occur on thin paper or paper of normal thickness.

Further, after the sheet is obliquely fed and comes into contact with the guide side plate, the guide side plate restricts the movement in the direction perpendicular to the conveying direction, so that a slip occurs between the skew roll and the sheet. . If the paper is scraped due to this slippage, it causes the generation of paper dust, and the paper dust may be scattered to each part of the apparatus and adversely affect the paper transport and the image quality.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems, to provide a sheet conveying apparatus which can reduce the sheet conveying resistance at a curved portion and can obtain a nip pressure suitable for the sheet thickness. To do.

[0007]

SUMMARY OF THE INVENTION To solve the above problems and to achieve the object, the present invention provides an outer peripheral guide surface of a curved conveyance path provided immediately before a straight conveyance path for aligning sheets. The first characteristic is that the bending guide plate to be formed is provided so as to be swingable about a shaft near the leading end in the transport direction, and spring means for urging the bending guide plate toward the inner peripheral side is provided.

Further, according to the present invention, a sensor for detecting the rotation amount of the bending guide plate, a means for changing the nip pressure of the skew roll, and a large nip pressure when the rotation amount is large so that the rotation amount is A second feature is that the control means for controlling the nip pressure to be small when the pressure is small is provided.

Further, according to the present invention, the nip pressure is kept at a predetermined value until the sheet reaches the conveying roll of the curved conveying path following the straight conveying path, and the bending guide plate is held at the timing when the sheet reaches the conveying roll. The third feature is that a control means for controlling the nip pressure changing means is provided so as to release the nip pressure on the assumption that the rotation amount of is small.

Further, according to the present invention, a sensor for detecting the thickness of the sheet, an urging means for oscillating the bending guide plate, and the urging means for controlling the urging means according to the thickness of the sheet are provided. A fourth feature is that the control means for determining the position of the bending guide plate is provided.

In addition to the fourth feature, the present invention provides a control means for increasing the nip pressure when the paper is thick and decreasing the nip pressure when the paper is thin according to the output of the paper thickness detection sensor. The fifth feature is that it is equipped.

Further, in addition to the fourth feature of the present invention, the nip pressure is maintained at a predetermined value until the paper reaches the conveyance roll of the curved conveyance path following the straight conveyance path, and the paper reaches the conveyance roll. A sixth feature is that a control means for controlling the nip pressure changing means is provided so as to release the nip pressure on the assumption that the sheet is thin at the timing.

[0013]

With the first and fourth characteristics, the bending guide plate swings in accordance with the characteristics of the conveyed sheet, that is, the thickness and the strength of the waist. In particular, according to the first feature, the paper oscillates. Further, according to the fourth feature, the urging means swings the urging member. Therefore, the curvature of the curved conveyance path becomes smaller as the sheet is thicker or stiffer, and the resistance when passing through the curved conveyance path is reduced.

In the second and fifth characteristics, the nip pressure is changed according to the characteristics of the sheet to be conveyed, that is, the thickness and the strength of the waist, and the sheet is conveyed so that the bending guide plate is largely rotated. Sometimes high nip pressures are obtained. Especially the second
According to the feature, the nip pressure is changed according to the amount of rotation of the bending guide plate. Further, according to the fifth feature, the nip pressure is changed according to the detected sheet thickness.

In the third and sixth features, the nip pressure is released after the sheet has passed the straight conveying path for aligning and has moved to the next conveying path. In particular, according to the third feature, the nip pressure is released on the premise that the amount of rotation of the bending guide plate is small, and according to the sixth feature, the nip pressure is released on the premise that the detected sheet thickness is thin. To be done.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of a recording apparatus including a sheet conveying apparatus according to an embodiment of the present invention. In the figure, the paper feed tray 1
Paper 2 is stacked and stored in the paper, and the paper 2 is
The uppermost roll is fed by the feed roll 3 in order. The fed-out sheet 2 is conveyed on a conveying path formed by a guide plate, and is sent to the fixing section 6 via the sheet aligning section 4 and the toner image forming section 5. Transport rolls 7a, 7b, 7 are provided in the transport path.
c and skew rolls 8a, 8b, 8c are arranged. Skew rolls 8a to 8 arranged in the sheet aligning unit 4
Solenoids 9a, 9b, 9c are connected to c as drive means for changing the nip pressure.

The skew roll 8c and the transport roll 7b
The curved guide plate 11 forming the outer peripheral guide surface of the curved conveyance path 10 between and is provided so as to be rotatable around the shaft 12. A tension coil spring 13 is provided on the opposite side of the bending guide plate 11 with respect to the shaft 12 and is biased counterclockwise in the figure by the tension coil spring 13. It is needless to say that a compression coil spring or a mainspring spring may be used instead of the tension coil spring 13 to generate the counterclockwise biasing force.

The sensor 14 detects that the bending guide plate 11 has rotated clockwise beyond a predetermined amount.
This is a so-called optical sensor that outputs a detection signal when the light between the light emitting unit and the light receiving unit is blocked. Transport rolls 7a and 7
A sheet detection sensor 16 is provided on the straight conveyance path 15 between the sheet conveyance path b and b. As the paper detection sensor 16, a reflection type optical sensor or the like generally used for paper jam detection can be used.
The sensor 14 is not limited to an optical sensor and may be replaced with a contact type limit switch.

The toner image forming section 5 includes a photoconductor drum 17 and a registration gate 18. The registration gate 18 is opened in synchronization with the timing of forming the toner image on the photoconductor drum 17, and transfer is performed. The toner image forming unit 5 is well known, and other components are not shown. The sheet on which the toner image has been transferred is conveyed by the vacuum transport 19 and discharged to the fixing unit 6. The control unit 21 controls the operations of the solenoids 8a to 8c based on the detection signals of the sensor 14 and the paper detection sensor 16, and is configured by a microcomputer. The operation of the control unit 21 will be described later.

Next, the operation of the bending guide plate 11 will be described in detail. FIG. 2 is an enlarged view of the curved conveyance path 10 and its peripheral portion. In the figure, the bending guide plate 1
No. 1 has no or extremely weak force for urging the bending guide plate 11 in the direction of arrow A when there is no sheet 2 or when an extremely thin sheet 2 (shown by a dotted line) is passing. Therefore, the bending guide plate 11 is biased in the direction of arrow B by the tension of the tension coil spring 13 to form a curved conveyance path having a large curvature.

On the other hand, while the thick sheet 2 (shown by the solid line) is passing, the waist strength or restoring force of the sheet 2 overcomes the force of the tension coil spring 13, and the bending guide plate 11 rotates in the direction of arrow A. The curvature of the curved conveyance path 10 becomes smaller as it moves. When the curvature of the curved conveyance path 10 becomes smaller, the contact resistance of the sheet passing through the curved conveyance path 10 decreases, so that smooth conveyance can be performed even if the nip pressure of the skew rolls 8a to 8c is small. In particular, the skew roll 8c, which plays a role of sandwiching and driving the paper 2 in order to guide the paper to the paper aligning unit 4, has been conventionally set to a higher nip pressure, but due to the reduction of the contact resistance, The nip pressure can be significantly reduced.

Further, when a thicker sheet 2 is conveyed, the bending guide plate 11 is largely rotated in the direction of arrow A, and the plate 1 formed on the back surface of the bending guide plate 11 is rotated.
1a reaches the concave portion of the sensor 14, and the optical axis of the sensor 14 is blocked. When a strong or thick sheet 2 that rotates the bending guide plate 11 as described above is conveyed, the conveyance abnormality may occur only by reducing the contact resistance due to the rotation of the bending guide plate 11. Conceivable. Therefore, the solenoid 9 is detected by the detection signal of the sensor 14.
The nip pressure can be changed by controlling a to 9c. This control operation will be described later in detail.

Next, a modified example of the rotation amount detecting portion of the bending guide plate 11 will be described. FIG. 3 is an example in which the rotation amount of the bending guide plate 11 is detected in three stages, and the same reference numerals as those in FIG. 2 indicate the same or equivalent portions. In this modified example, a sensor 20 is provided in which the light emitting portion and the light receiving portion are separated and are opposed to each other. The first light emitting portion 22a is paired with the first light receiving portion 22b, and the second light emitting portion 23a is paired with the second light receiving portion 23b.
When the bending guide plate 11 is at the position P1, the light emitted from the first light emitting portion 22a toward the first light receiving portion 22b is blocked. Further, the bending guide plate 11 is located at the position P2.
If it is, the first light emitting portion 22a to the second light receiving portion 22b
Both the light emitted toward and the light emitted from the second light emitting portion 23a toward the second light receiving portion 23b are blocked. Detection signals of the light blocking / light transmitting state by these sensors are sent to the control unit 21. Then, the solenoids 9a to 9c can be controlled by this detection signal to change the nip pressure. This control operation will be described later in detail.

Next, one example of the nip pressure changing means of the skew roll will be described in detail with respect to the skew roll 8a. FIG. 4 and FIG. 5 are side views showing the main configuration of the nip pressure changing means. First, in FIG. 4, the pressurizing side 81 of the skew roll 8a is rotatably supported by one end of an arm 25 that rotates around the support shaft 24. Further, one end of a tension coil spring 27 is hooked on a pin 26 provided at the other end of the arm 25, and the tension coil spring 27
The other end of is engaged with a pin 92 of a plunger 91 of the solenoid 9a. Conveying path 28 in the sheet aligning section 4
Is formed by an upper guide plate 29 and a lower guide plate 30.

When the solenoid 9a is not energized, the plunger 91 is held by the tension of the tension coil spring 27 in contact with the vertical plate of the stopper 93 which also serves as a holding portion of the solenoid 9a. On the other hand, when the solenoid 9a is biased, the plunger 91 is biased in the direction of arrow C, and as a result, the tension of the tension coil spring 27 increases. This increase in tension increases the force that biases the pressurizing side 81 of the skew roll 8a in the direction of arrow D via the arm 25. That is, the nip pressure between the pressing side 81 and the driving side 82 of the skew roll 8a sandwiching the sheet 2 is increased.

On the other hand, in the example of FIG. 5, the nip pressure is released when the solenoid 9a is energized. In the figure, one end of the tension coil spring 27 is hooked on the pin 26 at one end of the arm 25 as in the example of FIG. 4, and one end of the arm 25 is further connected to the plunger 91 of the solenoid 9a. ing. The other end of the tension coil spring 27 is fixed to the fixing portion 31 of the device body.

With this construction, the nip pressure is applied by the tension coil spring 27 when the solenoid 9a is not energized. Then, this nip pressure is released by energizing the solenoid 9a. That is, by urging the solenoid 9a, the plunger 91 is biased in the direction of the arrow E, and as a result, the arm 25 rotates about the support shaft 24 and the pressing side 8 of the skew roll 8a.
1 is biased in the direction of arrow F, and the nip pressure is released.

Next, the operation of the control unit 21 for changing the nip pressure of each of the skew rolls 8a to 8c in the sheet aligning unit 4 in the above configuration will be described. Note that FIG.
In the description of FIG. 10, each of the sensors 14 and 20 outputs a high-level detection signal when the bending guide plate 11 is detected, that is, when the light of each sensor is blocked.

FIG. 6 is a functional block diagram when the nip pressure is changed by the detection signal of the sensor 14 under the configuration of FIG. 4 in which the nip pressure increases when the solenoid is energized. In the figure, the sensor 14 bends the bending guide plate 11
Is detected, the detection signal is input to the solenoid driving units 211, 212, and 213 of the control unit 21. In response to this detection signal, each of the solenoid drive units 211 to 213 outputs a drive signal to the solenoid 9a, 9b, 9c. As a result, the solenoids 9a to 9c are urged to increase all the nip pressures of the skew rolls 8a to 8c. As described above, when the thick paper or the strong paper is conveyed, the sensor 14 detects that the turning amount of the bending guide plate 11 is large, and a large conveying force suitable for conveying the thick paper or the like is obtained.

Here, the skew roll 8 is not always required.
It does not increase the nip pressure for all of a-8c. That is, at least one pair of the skew rolls 8a to 8c may be provided with the configuration of FIG. 4 for changing the nip pressure, and the nip pressure may be changed only for the skew rolls.

Next, FIG. 7 shows a structure in which the number of skew rolls for increasing the nip pressure is changed according to the amount of rotation of the bending guide plate 11 under the structure of FIGS. 3 and 4.
In the figure, when the detection signal of the bending guide plate 11 is output by the first light receiving section 22b of the sensor 20, the solenoid drive section 211 outputs a drive signal to the solenoid 9a. Further, the bending guide plate 11 by the second light receiving portion 23b
Is supplied to the solenoid drive units 212 and 213, and these solenoid drive units 212 and 213 output drive signals to the solenoids 9b and 9c. Thus, the bending guide plate 1 detected by the sensor 20
The number of skew rolls that increase the nip pressure can be changed in accordance with the rotation amount of 1 to obtain the conveyance force according to the sheet.

Incidentally, the correspondence between the detection signal of the sensor 20 and the number of skew rolls for increasing the nip pressure is not limited to that shown in FIG. 7, and for example, the detection signal of the first light receiving portion 22b is transferred to the solenoid driving portion 211 and It may be supplied to 212 and the detection signal of the 2nd light sensing portion 23b may be supplied to solenoid actuator 213. Further, the detection signal of the first light receiving section 22b may be supplied to the solenoid driving section 212, and the detection signal of the second light receiving section 23b may be supplied to the solenoid driving sections 211 and 213.

Further, FIG. 8 shows skew rolls 8a to 8c.
Among the other skew rolls, leaving at least one pair among them, the nip pressure is released when the solenoid is energized, and the other skew rolls have a configuration in which the nip pressure is not changed. It is a block. Here, an example is shown in which the nip pressure of only the skew roll 8a is released. In the figure, the detection signal of the sensor 14 is inverted by the inverter 214 and
Entered in 2. The solenoid drive unit 212 outputs a drive signal to the solenoid 9b in response to an input signal from the sensor. As described above, when the detection signal of the sensor 14 is not output, that is, when the weak or thin paper is being conveyed, the detection signal is supplied to the solenoid drive unit 212 to energize the solenoid 9b and skew. The nip pressure of the roll 8b is released. Therefore, if the nip pressure of the skew rolls 8a to 8c is set to a high value in advance and the nip pressure of the skew roll 8b is released, the transport force in the sheet aligning device 4 is reduced as a whole suitable for transporting thin paper. It

Further, FIG. 9 is a functional block diagram when the skew rolls 9a to 9c are all arranged in the configuration of FIG. 5 to release the nip pressure when the solenoid is energized under the configuration of FIG. is there. In this example, the first light receiving unit 22b
And the detection signal of the second light receiving unit 23b is sent to the inverter 32,
33, and the solenoid drive units 211 to
13 as shown.

In this example, when the bending guide plate 11 is detected by the light receiving portions 22b and 23b, the solenoids 9a to 9c are not energized and therefore the nip pressure is not released. Then, when the bending guide plate 11 is not detected by the first light receiving portion 22b and the second light receiving portion 23b, that is, when the thin paper or the weak paper is being conveyed, the solenoids 9a to 9c are urged, and therefore the nip is reduced. The pressure is released. Here, the correspondence between the light receiving portion 22b and the light receiving portion 23b and the respective solenoids 9a to 9c is not limited to the illustrated example, and the point is that the number of solenoids to be biased can be changed according to the amount of rotation of the bending guide plate 11. It should be done.

Further, FIG. 10 shows a case where the nip pressure is changed in the configuration of FIG. 5 based on the detection signal of the sheet detection sensor 16 and the detection signal of the sensor 14 or the sensor 20 in the configuration of FIG. 2 or 3. It is a block diagram showing a control function. In FIG. 10, the paper detection signal from the paper detection sensor 16 is inverted by the inverter 34 and supplied to the solenoid drive units 211 to 213. That is, when the sheet is detected, the solenoid is de-energized, and the nip pressure due to the tension of the tension coil spring 27 is obtained. The paper detection signal is held by the holding means 44 until a release signal described later is supplied. A well-known means such as a flip-flop circuit can be used as the holding means 44.

On the other hand, the paper detection signal is sent to the timer means 35.
Is output to. In the timer means 35, the leading end of the conveyed sheet is conveyed by the conveying roll 7c in the next step of the sheet aligning device 4.
The time for obtaining the timing of being pinched by the sheet, that is, the time required to convey the sheet from the position of the sheet detection sensor 16 to the position of the conveying roll 7c is set. The timer means 35 is activated in response to the sheet detection signal, and the time-up signal is a holding signal via the AND gate 36 as a release signal for changing the solenoid from the non-excited state to the excited state. 44 is input. The hold signal 44 is reset by this release signal, the output of the inverter 34 is inverted to a high level, and the drive signals are output from the solenoid drive units 211-213 to the solenoids 9a-9c. As a result, the skew roll 8a-
The nip pressure of 8c is released, and the sheet is transported to the toner image forming unit 5 by the transport roll 7c.

In this embodiment, the nip pressure is not released when the bending guide plate 11 is detected by the sensor 14 or 20, that is, when a thick sheet is conveyed. That is, the timer means 3
The time-up signal of No. 5 is supplied to the solenoid drive units 211 to 213 via the AND gate 36. Then, the other input of the AND gate 36, that is, the detection signal of the bending guide plate 11 by the light receiving portion 22b or 23b of the sensor 14 or the sensor 20 is inverted by the inverter 37 and supplied to the AND gate 36. The AND gate 36 does not open when the signal is high. As a result, the solenoids 9a-9c are not energized and the nip pressure is not released. In this way, when it is detected that thin paper is being conveyed, the nip pressure of the skew rolls 8a to 8c is released at the timing of shifting to the next step, so that an excessive conveying force is not applied.

Next, a second embodiment of the present invention will be described. In the second embodiment, the bending guide plate 11 is not rotated by the repulsive force of the paper, but the thickness of the paper is detected by a sensor, and the biasing means such as a tension coil spring is used based on the detection result. The bending guide plate 11 is positively rotated.

FIG. 11 is a block diagram of a recording apparatus including a sheet conveying apparatus according to the second embodiment of the present invention, and the same reference numerals as those in FIG. 1 indicate the same or equivalent portions. In the figure, a paper thickness detection sensor 38 is a transmissive optical sensor and detects the paper thickness based on the amount of light transmission. That is, the detection signal of the paper thickness detection sensor 38 is supplied to the control unit 21, and is conveyed, for example, by referring to a correspondence table between the size of the detection signal and the paper thickness, or by comparing it with a predetermined threshold value. The thickness of the paper that is stuck.

A shaft of a stepping motor 39 is connected to the shaft 12 of the bending guide plate 11. The stepping motor 39 and the shaft 12 may be directly connected, but may be connected using a connecting means such as a gear or a belt. The structure for rotating the bending guide plate 11 continues to be as shown in FIG.
2 will be described.

FIG. 12 is a schematic view showing a driving means for rotating the bending guide plate 11. In the figure, a closed position detection sensor 40 is provided to detect the closed position of the bending guide plate 11. This closed position detection sensor 40
May be a limit switch arranged so as to contact the edge of the bending guide plate 11 in the closed position, or may be an optical sensor. The tension coil spring 41 has one end coupled to the edge of the bending guide plate 11 and the other end fixed to the apparatus body. The bending guide plate 11 is biased in the opening direction (the direction of arrow A) by the tension coil spring 41, while the bending guide plate 11 is moved by the stepping motor 39.
Is urged in the closing direction (the direction of arrow B). The compression coil spring 43 having the buffer member 42 at one end and fixed to the apparatus main body at the other end is the tension coil spring 41.
This is a positioning means for the open position (the position of the bending guide plate 11 shown by the dotted line in the figure) when the bending guide plate 11 is biased by. Further, a buffer member 44 is provided as a positioning means on the closed side of the bending guide plate 11. The cushioning member 44 and the cushioning member 42 may be those normally used as cushioning members such as rubber, sponge, or cork plate. Needless to say, the cushioning members 44 are provided at the left and right ends in the transport direction so as not to obstruct the transport of the paper.

Next, the operation of the second embodiment will be described. 13, in step S1, it is determined whether or not there is a detection signal from the paper thickness detection sensor 38, and if the determination is affirmative, the process proceeds to step S2 to refer to the correspondence table of the signal level and the thickness data, or Recognize the thickness of the paper by comparing it with the threshold value. In step S3, a predetermined register of the control unit 21 is set according to the recognized thickness of the sheet. Here, the flag is set to "1" for thick paper. In step S4, it is determined whether or not the leading edge of the sheet has been detected by the sheet detection sensor 16. This can be detected by whether or not the output signal of the paper detection sensor 16 has reached a predetermined level of H or L. If the leading edge of the paper is detected, the process proceeds to step S5, and two timers (T1, T
2) Start up. The timer T1 is set with the time until the leading edge of the paper reaches the position of the skew roll 8c, and the timer T2 is set with the time until the trailing edge of the paper passes through the position of the skew roll 8c.

In step S6, it is determined whether or not the paper is thick based on the planned value, depending on whether or not the flag is "1". If the paper is thick, the process proceeds to step S7 to determine whether the timer T1 has timed out. If the determination is affirmative, the process proceeds to step S8, and the stepping motor 39 is deenergized (off). As a result, the biasing force of the bending guide plate 11 in the closing direction is released, and it is rotated in the opening direction by the tension coil spring 41. In step S9, it is determined whether or not the timer T2 started in step S5 has timed out. When the time is up, the process proceeds to step S10, and the stepping motor 39 is excited (turned on) to turn the bending guide plate 11 in the closing direction. Step S1
At 1, it is determined whether or not the bending guide plate 11 is detected by the closed position detection sensor 40. If this determination is affirmative, the process proceeds to step S12, in which the stepping motor 39 is kept in the excited state and its rotation is stopped to maintain its position.

By the above operation, when the thick paper is carried, the curvature of the curved carrying path 10 immediately before the paper arranging section 4 can be made small, and the resistance at the time of carrying can be reduced.

The second embodiment can be modified as follows. That is, when the sheet thickness detection sensor 38 detects the sheet thickness, the nip pressure of the skew rolls 8a to 8c is changed according to the thickness. By doing so, it is possible to solve the problem caused by increasing the nip pressure more than necessary.

Note that the nip pressure can be changed by referring to FIGS.
It can be realized by the same operation as described for 0. That is, the output signal of the paper thickness detection sensor 38 may be treated in the same manner as the output signal of the sensor 14 or the sensor 20. Here, in order to treat the output signal of the paper thickness detection sensor 38 in the same manner as the output signal of the sensor 20, the output signal of the paper thickness detection sensor 38 is based on a correspondence table that can be recognized in at least three stages. To determine the paper thickness.

[0048]

As is apparent from the above description, according to the present invention, the following effects can be obtained. According to the first and fifth aspects of the invention, the bending guide plate defining the outer peripheral side guide surface of the curved conveyance path oscillates according to the characteristics of the conveyed paper, that is, the thickness and the strength of the waist. Therefore, the substantial curvature of the curved conveyance path is smaller for thicker paper or stronger paper, and the resistance when passing through the curved conveyance path is reduced. As a result, it is possible to reduce the nip pressure of the skew roll in the straight conveyance path that follows the curved conveyance path, and it is possible to prevent the occurrence of scratches on the sheet and buckling.

According to the second, third, sixth and seventh aspects of the present invention, an appropriate nip pressure can be obtained according to the rotation amount of the bending guide plate or the sheet thickness detected by the sheet thickness detecting means. As a result, reliable transport force can be obtained even with thick paper,
For thin paper, the nip pressure is not increased more than necessary, so it is possible to prevent scratches and buckling on the paper.

In the inventions of claims 4 and 8, the nip pressure is released after the sheet has passed the straight conveying path for aligning and has moved to the next conveying path. Therefore,
Since the nip pressure is not applied when it is not necessary, the slip between the paper and the skew roll can be reduced, and the occurrence of scratches on the paper can be prevented.

[Brief description of drawings]

FIG. 1 is a system diagram showing a configuration of a recording apparatus including a conveying apparatus according to a first exemplary embodiment of the present invention.

FIG. 2 is an enlarged view showing a main part of a transport path.

FIG. 3 is an enlarged view showing a main part of a modified example of a transport path.

FIG. 4 is a diagram showing a configuration of a nip pressure adding device.

FIG. 5 is a diagram showing a configuration of a nip pressure release device.

FIG. 6 is a block diagram showing a main function of a nip pressure addition control device based on one sensor output.

FIG. 7 is a block diagram showing a main function of a nip pressure addition control device based on two sensor outputs.

FIG. 8 is a block diagram showing a main function of the nip pressure release control device based on one sensor output.

FIG. 9 is a block diagram showing a main function of a nip pressure release control device based on two sensor outputs.

FIG. 10 is a block diagram showing a main function of a nip pressure release timing control device based on a paper detection sensor output.

FIG. 11 is a system diagram showing a configuration of a recording apparatus including a conveying device according to a second embodiment of the present invention.

FIG. 12 is a diagram showing a configuration of a bending guide plate swinging device.

FIG. 13 is a flowchart showing the operation of the second embodiment.

[Explanation of symbols]

1 ... Paper feeding tray, 2 ... Paper, 4 ... Paper aligning section, 8a
~ 8c ... skew roll, 9a ~ 9c ... solenoid,
10 ... Curved conveyance path, 11 ... Bending guide plate, 12 ...
Shaft, 13 ... tension coil spring, 14 ... sensor, 2
DESCRIPTION OF SYMBOLS 1 ... Control part, 22b ... 1st light receiving part, 23b ... 2nd light receiving part

Claims (8)

[Claims] 1. A straight conveying path having a plurality of pairs of skew rolls for obliquely feeding the sheet for guiding the sheet to a reference position in a direction orthogonal to the conveying direction, and curves provided before and after the straight conveying path. In a sheet conveying device having a conveying path, a curved guide plate that forms an outer peripheral side guide surface of a curved conveying path that is arranged immediately before the linear conveying path, and is provided at an end portion of the curved guide plate that is closer to the linear conveying path. A shaft provided at right angles to the paper transport direction and parallel to the paper to be transported in order to swingably support the bend guide plate; A sheet conveying device, comprising: a turning force imparting spring that urges the center of the curved conveying path to rotate toward the inner peripheral side. 2. A sensor means for detecting the amount of movement of the bending guide plate when the bending guide plate is rotated to the outer peripheral side against the elastic force of the turning force imparting spring, and the nip pressure of the skew roll. In order to change, the nip pressure changing means provided on at least one pair of skew rolls, and the nip pressure when the amount of movement is large and the nip pressure when the amount of movement is small according to the detected amount of movement. The sheet conveying apparatus according to claim 1, further comprising a control unit that controls the nip pressure changing unit so as to reduce the nip pressure. 3. A sensor means for detecting the amount of movement of the bending guide plate when the bending guide plate is rotated to the outer peripheral side against the elastic force of the turning force imparting spring, and the nip pressure of the skew roll. In order to change, depending on the nip pressure changing means provided for each skew roll and the detected operation amount, the nip pressure is increased when the operation amount is large and is decreased when the operation amount is small. Therefore, a control means for controlling the number of the nip pressure changing means to be biased is provided.
The paper transport device described. 4. A sensor means for detecting an operation amount of the bending guide plate when the bending guide plate is rotated to the outer peripheral side against the elastic force of the turning force imparting spring, and a curve immediately before the straight conveying path. A sheet detecting means provided upstream of the conveying path; a conveying roll provided on the second curved conveying path immediately after the straight conveying path; a nip pressure releasing means for releasing a nip pressure of the skew roll; When the detection unit detects the sheet, the nip pressure releasing unit is de-energized, and at the timing when the conveying force is applied by the conveying roll, the nip pressure releasing unit is provided on condition that the operation amount is smaller than a predetermined value. 2. The sheet conveying apparatus according to claim 1, further comprising a control unit that controls to urge the sheet. 5. A straight conveying path having a plurality of pairs of skew rolls for obliquely feeding the sheet to guide the sheet to a reference position in a direction orthogonal to the conveying direction, and curves provided before and after the straight conveying path. In a sheet conveying device having a conveying path, a curved guide plate that forms an outer peripheral side guide surface of a curved conveying path that is arranged immediately before the linear conveying path, and is provided at an end portion of the curved guide plate that is closer to the linear conveying path. A shaft provided at right angles to the paper transport direction and parallel to the paper to be transported in order to swingably support the bend guide plate; An urging means for swinging about the center, a thickness detecting means provided upstream of the curved conveying path arranged immediately before the straight conveying path for detecting the thickness of the conveyed sheet, and a detected sheet thickness. If is thicker than the planned value, The rotation guide plate about the axis to the outer peripheral side to the predetermined position, and when the paper thickness is thin, the bending guide plate to rotate on the inner side to the predetermined position about the axis. A sheet conveying apparatus comprising: a control unit that controls a biasing unit. 6. A nip pressure changing unit provided on at least one pair of skew rolls for changing the nip pressure of the skew rolls, wherein the control unit controls the nip pressure when the detected sheet thickness is thick. 6. The sheet conveying apparatus according to claim 5, further comprising a configuration for controlling the nip pressure changing means so as to reduce the nip pressure when the pressure is large and the sheet thickness is thin. 7. A nip pressure changing unit provided for each skew roll to change the nip pressure of the skew roll, wherein the control unit controls the nip pressure when the detected sheet thickness is thick. 6. The sheet conveying apparatus according to claim 5, further comprising a configuration for controlling the number of the nip pressure changing means to be urged to reduce the nip pressure when the sheet is large and the sheet thickness is thin. 8. A nip between the skew detecting roller, a sheet detecting unit provided upstream of the curved transport path immediately before the straight transport path, a transport roll provided at a second curved transport path immediately after the straight transport path, and a skew roll. At the timing when the nip pressure releasing means for releasing the pressure and the nip pressure releasing means when the sheet is detected by the sheet detecting means are in the non-energized state and the conveying force is applied by the conveying roll, the sheet thickness is 6. The sheet conveying apparatus according to claim 5, further comprising a structure for controlling to urge the nip pressure releasing means on condition that the value is smaller than a predetermined value.