JP2006264807A - Sheet carrying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet carrying device, capable of reducing settling time in which contact pressure of a feed roll to sheet paper or the like is constant under addition of a prescribed load by modifying the shape as well as step signals in the profile of control signals input to a drive source. <P>SOLUTION: This sheet carrying device is provided with a drive source to which a feed pressure signal is input to generate drive force, a feed roll to get in contact with an upper surface of a sheet bundle housed in a tray with prescribed feed pressure to feed a sheet from the tray, and a drive control part to provide a feed pressure signal for feeding the sheet to the drive source. The feed pressure signal provided by the drive control part to the drive source has a feed start part having a high set pressure range higher than a set value of the feed pressure at normal time at least at a head part of a signal profile. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet conveying apparatus used in an image forming apparatus such as a copying machine and a printer using an electrophotographic system or an ink jet printer system.

JP 05-032356 A JP 06-048614 A Japanese Patent Laid-Open No. 07-137858 JP 07-237759 A Japanese Unexamined Patent Publication No. 07-247039 Japanese Patent Laid-Open No. 08-188291 JP 09-188430 A Japanese Patent Laid-Open No. 09-194067 JP-A-10-045272 JP 2000-264460 A JP 2001-213540 A

  2. Description of the Related Art Conventionally, in an image forming apparatus such as an electronic copying machine or a printer, a unit that feeds a sheet one by one from a sheet feeding tray by a sheet conveying device is mounted on a sheet feeding unit that accommodates sheets. . A sheet conveying device used in a general image forming apparatus is composed of a feeding roll positioned at a feeding side end of a sheet sheet accommodated in a sheet feeding tray, and a separation mechanism disposed downstream thereof. . As the separation mechanism, a mechanism is used in which a feed roll driven in the feeding direction with respect to a sheet paper or the like and a roll member for performing a separation action are arranged to face each other.

  The separation mechanism is configured to connect a driving unit to the retard roll via a torque limiter or the like so as to drive the retard roll in the direction opposite to the paper feeding direction. When only one sheet of paper or the like enters between the feed roll and the retard roll, the retard roll stops and only the feeding operation by the feed roll is performed. When a sheet or the like enters between both rolls, the feed roll feeds the uppermost sheet sheet and drives the retard roll in the return direction for the lower sheet sheet. As a result, the sheet paper or the like is separated.

  In the case of using the sheet conveying device, for example, in the case of a thin sheet paper or the like and in the case of a thick sheet paper or the like, the feeding action by the feeding roll and the separating action by the separation mechanism cannot be performed in the same state. There's a problem. However, in the conventional sheet conveying apparatus, the pressing force between the feed roll and the sheet and between the feed roll and the retard roll is set for the sheet paper having an average property. In addition, when a misfeed or double feed occurs, maintenance personnel are called to inspect and repair. In addition, even when making a copy using an OHP film or the like, for a sheet such as a film, under conditions different from those for a paper sheet, between a feed roll and a sheet, and a feed roll and a retard roll It is necessary to set the pressing force between.

  In order to solve the above problems, it has been proposed to use a means for adjusting the nip pressure between the feed roll and the retard roll constituting the separation mechanism. For thin paper such as tracing paper, poorly separable sheets such as OHP film, and normal copying sheet paper, etc., by changing the pressure at the separation part, It is possible to prevent the occurrence of feed and double feed.

However, in the separation mechanism as described above, it is necessary to adjust the pressing force between the feed roll and the retard roll in accordance with the sheet paper fed from the paper feed tray. There is a problem that it is troublesome to adjust the pressing force each time the value changes.
In addition, when double feeding of sheet paper or the like occurs, it is necessary to repeatedly adjust the pressing force between the feed roll and the retard roll until the multi-feed does not occur in the sheet conveying apparatus. There is a great burden on unfamiliar operators.
Further, misfeed or double feed of sheet paper or the like may change depending on the moisture content of the sheet paper or the like.

  In addition to the above problems, if the pressing force between the feed roll and the retard roll is increased, the double feed is reduced. However, if the pressing force is increased and the pressing force is decreased, the misfeed is decreased. However, there is a problem that double feed increases. Also, there is a problem that misfeeding conditions change due to the strength of the pressing force of the delivery roll on the sheet paper stored in the paper feed tray, and it is difficult to set these conditions accurately. It is.

  Therefore, both the misfeed detection sensor and the double feed detection sensor or one of the detection means are arranged in the downstream portion of the sheet conveying device, and the detection information is input to the control device, so that the nip pressure in the sheet separation mechanism is reduced. There is known an apparatus capable of automatically adjusting and adjusting the pressing force applied to a sheet paper or the like by a delivery roll (see Patent Documents 1 to 11).

  Further, the applicant of the present application can move relative to the sheet support, an electromagnetic drive source that generates a driving force of a magnitude corresponding to the pressure instruction signal in the movable part, a sheet support that supports the sheet, and the sheet support. A roll, rotational drive means for rotationally driving the roll, a movable part of the electromagnetic drive source and the roll, the driving force generated in the movable part being transmitted to the roll, An application has been filed for a sheet conveying apparatus including a driving force transmission mechanism that presses against a sheet supported by the sheet support, and a control unit that controls the pressure instruction signal (Japanese Patent Application No. 2004-192044). According to the present application, since the pressure of the roll pressed against the sheet is generated by the electromagnetic drive source, the roll pressure is controlled finely at high speed to prevent the occurrence of misfeeds and double feeds. It becomes possible.

  As described above, in the former sheet conveying apparatus, the feeding roll is pressed against the sheet paper or the like by the spring whose one end is connected to the arm member supported by the shaft of the feed roll, to the sheet paper or the like. The pressing force is adjusted by controlling a stepping motor or the like connected to the other end of the spring. In the latter prior application, the delivery roll is connected to an electromagnetic drive source that generates a driving force of a magnitude corresponding to the pressure instruction signal in the movable portion, and is pressed against the sheet paper or the like by the driving force of the electromagnetic drive source. Therefore, the adjustment of the pressing force on the sheet paper or the like is made by adjusting the driving force of the electromagnetic driving source.

  However, in the above prior art, since a constant control signal is input to a driving source such as a stepping motor and a solenoid, a constant load is applied for a settling time during which the contact pressure of the delivery roll to the sheet paper is constant. There is a problem that it cannot be reduced below.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and the object of the present invention is to change not only the step signal but also the shape of the profile of the control signal input to the drive source. Accordingly, an object of the present invention is to provide a sheet conveying apparatus capable of reducing the settling time during which the contact pressure of the delivery roll with respect to the sheet paper or the like is constant while applying a certain load.

  That is, according to the present invention, a driving source that generates a driving force when a feeding pressure signal is input, and a tray that is connected to the driving source and contacts the upper surface of a sheet bundle accommodated in the tray with a predetermined feeding pressure. In the sheet conveying apparatus having a feed roll for feeding a sheet from the sheet and a drive control unit for supplying a feed pressure signal for feeding the sheet to the drive source, the feed pressure signal supplied to the drive source by the drive control unit Is a sheet conveying apparatus characterized by having a feeding start portion having a high set pressure region at least higher than a set value of the feeding pressure in a steady state at the head portion of the signal profile. According to this, it is possible to reduce the settling time during which the contact pressure of the delivery roll with respect to the sheet paper or the like is constant under a constant load.

  In the present invention, the delivery start portion of the feed pressure signal may have a low set pressure region lower than the set value of the feed pressure in the steady state following the high set pressure region. The settling time during which the contact pressure with respect to the sheet or the like is constant can be further reduced under the application of a constant load.

  Note that the set value of the feeding pressure in a steady state is the sheet characteristic value such as the friction coefficient, size, weight, and air permeability of the sheet to be fed, or the roll coefficient such as the friction coefficient, hardness, and material of the roll to be conveyed. It is necessary to set the optimum value according to the characteristic value and the spatial arrangement of the drive source and drive gear, etc. In the case of plain paper used in electronic copying machines and printers, a feeding pressure of about 0.5 to 2.0 N is required. Used. Further, when a sheet having a high adhesion between sheets such as coated paper is conveyed, it is necessary to use a higher feeding pressure.

  In addition, the larger the high set pressure area, the shorter the time to grounding, so the maximum value of the drive source that generates the feed pressure is within the range where there is no other adverse effect such as the rigidity of the feed device. It is desirable to give. Further, it is desirable to keep the duration between the start of the grounding operation and the actual roll contact.

  In addition, the size and duration of the low set pressure area is intended to decelerate the roll accelerated by the force applied in the high set pressure area before grounding and to reduce vibration after grounding. It must be optimally adjusted by taking into account the physical properties such as the size, duration, and sliding resistance, viscosity, and elasticity of the entire device with respect to the grounding operation of the roll. In a system where the effect of deceleration due to physical characteristics is hardly expected, it is desirable to apply a force in the opposite direction to the grounding.

  According to the present invention, the profile of the control signal input to the drive source is changed not only by the step signal but also by the shape, so that the settling time during which the contact pressure of the delivery roll to the sheet paper is constant is applied with a constant load. It is possible to provide a sheet conveying device that can be reduced in the above.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are views showing a first embodiment in a sheet conveying apparatus according to the present invention.

  FIG. 1 is a diagram illustrating a delivery roll mechanism 10 in the sheet conveying apparatus of the present embodiment. The delivery roll mechanism 10 includes an actuator 12 as a driving source, a delivery roll 14 positioned upstream with respect to a separation mechanism direction (not shown) that separates the sheet P, a holding member 15 that holds the actuator 12 in an apparatus frame (not shown), and one end portion. From a spring 18 that is rotatably fixed to the apparatus frame and is supported at the other end by a support member 16 that rotatably supports the delivery roll at the end of the delivery roll, and a holding member 14 and the support member 16 that are elastically connected. It is roughly structured. The actuator 12 includes a main body portion 12 a held by the holding member 14 and a movable portion 12 b that contacts the support member 16 and contacts and separates the feeding roll 14 and the sheet P. Below the delivery roll mechanism 10, the sheet P is stored in a paper feed tray (not shown).

  In the above configuration, the delivery roll 14 in the sheet conveying apparatus of the present embodiment operates as follows. When no control signal is input to the actuator 12 (when the actuator is OFF), the support member 16 that is in contact with the actuator 12 is urged clockwise by the spring 18 and the delivery roll 14 is separated from the sheet P. Yes. On the other hand, when a control signal is input to the actuator 12 (when the actuator is ON), the movable portion 12b of the actuator 12 is lowered, and the support member 16 that is in contact with the actuator 12 resists the biasing force of the spring 18. The sheet is rotated clockwise and the delivery roll 14 is lowered and brought into contact with the sheet P.

  FIG. 2 is a block diagram illustrating the feeding roll unit 20 in the sheet conveying apparatus of the present embodiment. The delivery roll unit 20 includes a grounding operation control unit 22 (drive control unit) to which set load information is input from a device control unit (not shown), and a paper feed load generator 24 to which a load control signal is input from the grounding operation control unit 22. (Actuator 12) and a paper feeding device 26 (sending roll 14 and the like) to which a load is applied from the paper feeding load generator 24 are schematically configured.

  FIG. 3 is a graph showing the voltage input to the actuator 12 and the behavior of the delivery roll at that time.

  FIG. 3A is a graph showing a voltage input to the conventional actuator 12. When the set load information is input to the ground load control unit 22, a step signal corresponding to the set load is input to the actuator 12. In the case shown in the figure, a step signal of voltage (low) input to the actuator 12 when the set load is low, and a step signal of voltage (high) input to the actuator 12 when the set load is high.

  FIG. 3B is a diagram illustrating the behavior of the delivery roll when a voltage (high) step signal is input to the actuator 12. In the case of this figure, the rise, which is the time during which the delivery roll 14 is in contact with the sheet, is fast, but has a characteristic that convergence to the set load is slow.

  FIG. 3C is a diagram illustrating the behavior of the delivery roll when a voltage (low) step signal is input to the actuator 12. In the case of this figure, the rise, which is the time during which the delivery roll 14 is in contact with the sheet, is slow, but has a characteristic that convergence to the set load is fast.

  FIG. 4 is a graph showing the voltage input to the actuator 12 in this embodiment and the behavior of the delivery roll 14 at that time.

  FIG. 4A is a graph showing a voltage input to the actuator 12 in the present embodiment. When the set load information is input to the ground load control unit 22, a signal having a profile corresponding to the set load is input to the actuator 12. In the case shown in the figure, a signal that is higher than the height of the signal value (set value of the steady-state feeding pressure) corresponding to the set load at the rising edge of the input signal profile regardless of the set load (send start part). High set pressure region) is input, and then a signal having a height corresponding to the set load is input.

  FIG. 4B is a diagram showing the behavior of the delivery roll 14 when a signal having the profile of FIG. 4A in this embodiment is input to the actuator 12. In the case of this figure, compared with FIG.3 (b) and FIG.3 (c), it has the characteristic that the rise which is the time when the delivery roll 14 contacts a sheet | seat is quick, and the convergence to a setting load is a little quick. ing.

  As described above, according to the sheet conveying apparatus of the present embodiment, the profile of the control signal input to the actuator 12 is changed to the shape as shown in FIG. The settling time during which the contact pressure is constant can be reduced as shown in FIG. 4B under a constant load.

  Next, a second embodiment of the sheet conveying apparatus according to the present invention will be described. In the present embodiment, the same components as those shown in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 5 is a graph showing the voltage input to the actuator 12 in this embodiment and the behavior of the delivery roll 14 at that time.

  FIG. 5A is a graph showing a voltage input to the actuator 12 in the present embodiment. When the set load information is input to the ground load control unit 22, a signal having a profile corresponding to the set load is input to the actuator 12. In the case shown in the figure, at a rising edge of the input signal profile, regardless of the set load, it is lower than the height of the signal value corresponding to the set load after a signal higher than the signal value height corresponding to the set load is input for a certain interval. A signal (low set pressure region) is input, and thereafter a signal having a height corresponding to the set load is input.

  FIG. 5B is a diagram illustrating the behavior of the delivery roll 14 when a signal having the profile of FIG. 4A in this embodiment is input to the actuator 12. In the case of this figure, compared with FIG.3 (b) and FIG.3 (c), the rise which is the time when the delivery roll 14 contacts a sheet | seat is quick, and convergence to a setting load is further FIG.4 (b). It has the characteristic that it is quick in comparison.

  As described above, according to the sheet conveying apparatus of the second embodiment, the profile of the control signal input to the actuator 12 is changed to the shape as shown in FIG. The settling time during which the contact pressure with respect to the sheet P is constant can be reduced as shown in FIG.

  Next, a third embodiment of the sheet conveying apparatus according to the present invention will be described. In the present embodiment, the same components as those shown in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 6 is a graph showing the voltage input to the actuator 12 in this embodiment and the behavior of the delivery roll 14 at that time.

  FIG. 6A is a graph showing a voltage input to the actuator 12 in the present embodiment. When the set load information is input to the ground load control unit 22, a signal having a profile corresponding to the set load is input to the actuator 12. In the case shown in the figure, the signal value corresponding to the set load is shown in a curved line after a signal higher than the signal value height corresponding to the set load is input for a certain interval at the rising edge of the input signal profile. A signal lower than this is input, and thereafter a signal having a height corresponding to the set load is input in a curved manner.

  FIG. 6B is a diagram illustrating the behavior of the delivery roll 14 when a signal having the profile of FIG. 4A in this embodiment is input to the actuator 12. In the case of this figure, compared with FIG.3 (b) and FIG.3 (c), the rise which is the time when the delivery roll 14 contacts a sheet | seat is quick, and convergence to a setting load is further FIG.5 (b). It has the characteristic that it is quick in comparison.

  As described above, according to the sheet conveying apparatus in the third embodiment, the profile of the control signal input to the actuator 12 is changed to the shape as shown in FIG. The settling time during which the contact pressure with respect to the sheet P is constant can be reduced as shown in FIG.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention.

FIG. 1 is a view showing a feeding roll mechanism of a first embodiment in a sheet conveying apparatus according to the present invention. FIG. 2 is a block diagram showing the delivery roll unit 20 in the first embodiment. FIG. 3 is a graph showing the voltage input to the conventional actuator and the behavior of the delivery roll at that time. FIG. 4 is a graph showing the voltage input to the actuator in the first embodiment and the behavior of the delivery roll at that time. FIG. 5 is a graph showing the voltage input to the actuator in the second embodiment and the behavior of the delivery roll at that time. FIG. 5 is a graph showing the voltage input to the actuator in the third embodiment and the behavior of the delivery roll at that time.

Explanation of symbols

  10: Delivery roll mechanism, 12: Actuator, 14: Delivery roll, 20: Delivery roll unit, P: Sheet

Claims (2)

A driving source that generates a driving force when a feeding pressure signal is input, and a feeding roll that is connected to the driving source and feeds a sheet from the tray by contacting the upper surface of a sheet bundle accommodated in the tray with a predetermined feeding pressure. And a drive control unit that supplies a feeding pressure signal for feeding the sheet to the driving source,
The feed pressure signal supplied to the drive source by the drive control unit has a delivery start portion having a high set pressure region at least higher than a set value of the feed pressure in a steady state at the head of the signal profile. A sheet conveying apparatus.   2. The sheet conveying apparatus according to claim 1, wherein the feeding pressure signal sending start unit has a low set pressure region lower than a set value of the feed pressure in a steady state following the high set pressure region.

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