JP2017202934A - Sheet transportation device, original reading device equipped with sheet transportation device, and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet transportation device capable of suppressing occurrence of a jam.SOLUTION: A sheet transportation device includes feeding means for feeding a sheet material, a transportation roller which is provided on a downstream side of the feeding means in a sheet transportation direction for transporting the sheet material that is fed to the downstream side along the transportation direction, a motor for driving the transportation roller, phase determination means for determining rotation phase of a rotor of the motor, and control means which controls a drive current on the basis of a value of a torque current component for generating a torque at the rotor of the motor and a value of an excitation current component which strongly affects a magnetic flux penetrating a winding of the motor, which are current components of the drive current flowing the winding of the motor, represented in a rotation coordinate system with the determined rotation phase as a reference. The feeding means, in a state in which a first sheet material having been fed by the feeding means is being transported by the transportation roller, starts feeding of a second sheet material that should be fed next to the first sheet material when a value of the torque current component of the drive current flowing in the winding of the motor changes from a value that is a specified value or higher to a value that is smaller than the specified value.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a sheet material conveyance technique.

  For example, the image forming apparatus conveys a recording material that is a sheet material stored in a storage unit, and forms an image on the recording material. The document reading apparatus conveys a document that is a sheet material and reads an image of the document. As one of the methods for increasing the throughput of the image forming apparatus and the document reading apparatus, it is conceivable to shorten the interval between the fed sheet materials. For this purpose, it is necessary to advance the feeding timing of the subsequent sheet material, but it is necessary to reliably detect that the rear end of the preceding sheet material has passed a predetermined position. For this reason, Patent Document 1 discloses a configuration in which two sensors are provided on the downstream side in the transport direction from the separation unit that separates the sheet material stacked on the stacking unit one by one. According to Patent Document 1, when a state in which two sensors detect a sheet material transitions to a state in which any one of the sensors does not detect a sheet material and there is a next sheet material in the stacking unit, The sheet material feeding operation is started.

Japanese Patent No. 5262844

  Since the configuration described in Patent Document 1 uses two sensors, the control is complicated. Further, if two or more sheets are partially overlapped with the separation portion and the state in which the sensor detects the sheet is continued, jamming may occur.

  The present invention provides a sheet conveying apparatus, a document reading apparatus, and an image forming apparatus that can suppress the occurrence of a jam.

  According to one aspect of the present invention, the sheet conveying apparatus includes: a stacking unit that stacks the sheet material; a feeding unit that feeds the sheet material stacked on the stacking unit; and a transport direction in which the sheet material is transported. A conveying roller that is provided downstream of the feeding unit and that conveys the sheet material fed by the feeding unit to the downstream side in the conveying direction; a motor that drives the conveying roller; and A phase determining means for determining the rotational phase of the rotor, and a current component of a drive current flowing in the winding of the motor, expressed in a rotating coordinate system based on the rotational phase determined by the phase determining means, The drive current flowing in the motor winding is based on the value of the torque current component that generates torque in the rotor of the motor and the value of the excitation current component that affects the strength of the magnetic flux passing through the motor winding. Control means for controlling an electric current, wherein the feeding means is a driving current that flows in a winding of the motor in a state where the conveying roller is conveying the first sheet material fed by the feeding means. When the value of the torque current component changes from a value equal to or greater than a predetermined value to a value smaller than the predetermined value, feeding of the second sheet material to be fed next to the first sheet material is started. Features.

  According to the present invention, the occurrence of jam can be suppressed.

1 is a configuration diagram of an image forming apparatus including a sheet conveying device according to an embodiment. 1 is a control configuration diagram of a document reading device according to an embodiment. FIG. 1 is a control configuration diagram of an image printing apparatus according to an embodiment. FIG. The figure which shows the relationship between the two-phase motor which consists of A phase and B phase, and d-axis and q-axis of a rotation coordinate system. The block diagram which shows the structure of the conveyance motor control part by one Embodiment. The functional block diagram of CPU by one Embodiment. Explanatory drawing of feeding control by one Embodiment. Explanatory drawing of feeding control by one Embodiment. Explanatory drawing of the state determination by one Embodiment. Explanatory drawing of the state determination by one Embodiment. The flowchart of feeding control by one Embodiment. The block diagram which shows the structure of the conveyance motor control part by other embodiment.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In addition, the following embodiment is an illustration and does not limit this invention to the content of embodiment. In the following drawings, components that are not necessary for the description of the embodiments are omitted from the drawings.

  FIG. 1 is a configuration diagram of an image forming apparatus 100 including a sheet conveying apparatus that conveys a sheet material according to the present embodiment. The image forming apparatus 100 includes a document reading device 201 and an image printing device 301. Hereinafter, the document reading apparatus 201 will be described. The paper feed tray 2 is a stacking unit on which documents as sheet materials are stacked. The pickup roller 3, the feeding roller 4, the separation roller 5, and the swing arm 12 constitute a separation feeding unit that separates the documents on the sheet feeding tray 2 one by one and feeds them to the conveyance path. The feed roller 4, the swing arm 12 and the pickup roller 3 are rotationally driven by a feed motor M1 which is omitted in FIG. That is, the driving of the feeding roller 4 and the driving of the pickup roller 3 are synchronized. The swing arm 12 is connected to the drive shaft of the feeding roller 4 via a torque limiter L1 (not shown). By the forward / reverse rotation of the feed motor M1, the peristaltic arm 12 is rotated via the drive shaft of the feed roller 4, so that the pickup roller 3 feeds a document loaded on the feed tray 2. And the retracted position above the paper feeding position.

  The feed roller 4 is in pressure contact with the separation roller 5 to form a nip portion. The feed roller 4 is rotationally driven in the document transport direction by the drive of the feed motor M1, thereby feeding the uppermost document to the transport path. Here, the separation roller 5 prevents the conveying force from being transmitted to the document under the document to be fed by a torque limiter L2 (not shown). As a result, even if two originals are overlapped and fed out, only one uppermost original is fed toward the conveyance path.

  In FIG. 1, the registration rollers 6, the conveyance rollers 7, the reading rollers 8 and 9, and the paper discharge rollers 11, which are conveyance rollers, respectively constitute a conveyance unit that conveys a document along a conveyance path. doing. The registration roller 6 is provided to correct the skew of the document fed by the separation feeding unit. The conveyance of the document is stopped when the leading edge of the document hits the stopped registration roller 6, and then the document is drawn and conveyed by the registration roller 6. That is, when the registration roller 6 rotates while the feeding motor M1 is stopped, the registration roller 6 conveys the original document that is nipped by the nip portion of the separation feeding unit. The document whose skew has been corrected by the registration roller 6 is transported downstream along the transport direction by the transport roller 7 and the reading rollers 8 and 9, and after the image of the document is read, by the paper discharge roller 11. The paper is discharged onto the paper discharge tray 10.

  The document reading device 201 is provided with a document reading unit 16 that reads an image on the first surface of a document to be conveyed. Reflected light from the document image illuminated by the illumination 20 at the reading position is guided to the image reading unit 21 by an optical system including a reflection mirror, and is converted into an image signal by the image reading unit 21. The image reading unit 21 includes a lens, a CCD as a photoelectric conversion element, a drive circuit for the CCD, and the like. The image signal output from the image reading unit 21 is subjected to various correction processes by the image processing unit 22 including a hardware device such as an ASIC, and then output to the image printing apparatus 301 by the control unit 400 described later. The In addition, the document reading device 201 is provided with a document reading unit 17 that reads an image on the second side of the document to be conveyed. The configuration of the document reading unit 17 is the same as the configuration of the document reading unit 16. The image information read by the document reading unit 17 is output to the image printing apparatus 301 in the same manner as described in the document reading unit 16. As described above, the document is read.

  The document set sensor SS1 detects whether or not documents are stacked on the paper feed tray 2. The document detection sensor SS2 detects a document on the downstream side of the separation feeding unit and on the upstream side of the registration roller 6. The conveyance sensor SS3 detects a document on the downstream side of the registration roller 6 and on the upstream side of the conveyance roller 7. The read sensor SS4 and the read sensor SS5 detect the document on the upstream side of the image reading units 16 and 17, respectively. The timing for reading the image of the document is determined based on the detection results of the lead sensor SS4 and the lead sensor SS5.

  FIG. 2 is a control configuration diagram of the document reading apparatus 201 according to the present embodiment. The control unit 400 includes a CPU 401, a ROM 402 in which a control program is stored, and a RAM 403 that is used as an area for temporarily storing control data and a work area for operations associated with control. The control unit 400 can send and receive data and commands to and from each connected unit.

  The control unit 400 controls the feed motor control unit 204 and the transport motor control unit 205 based on the input signals from the above-described sensors. The feed motor control unit 204 controls the feed motor M <b> 1 in response to a command output from the control unit 400. As a result, the feeding roller 4 is driven. Further, the transport motor control unit 205 controls the transport motor M <b> 2 in accordance with a command output from the control unit 400. As a result, each roller of the transport unit including the registration roller 6 is driven. By dividing the drive system into two in this manner, even when a sudden load is applied to the feeding motor M1, the stability of the document conveyance speed in the conveyance unit by the conveyance motor M2 is ensured.

  As described above, the control unit 400 controls the operation sequence of the document reading apparatus 201. A portion of the document reading device 201 excluding the document reading units 16 and 17 corresponds to the document feeding device.

  Next, the configuration and function of the image printing apparatus 301 will be described. Inside the image printing apparatus 301, sheet storage trays 302 and 304 are provided. Each of the sheet storage trays 302 and 304 can store different types of sheet materials. For example, A4 size plain paper is stored in the sheet storage tray 302, and A4 size thick paper is stored in the sheet storage tray 304. The sheet material includes paper, a resin sheet, cloth, an OHP sheet, a label, and the like, and an image is formed on these sheet materials.

  The sheet material stored in the sheet storage tray 302 is fed by the paper feed roller 303 and sent to the registration roller 308 by the transport roller 306. Further, the sheet material stored in the sheet storage tray 304 is fed by the paper feed roller 305 and sent out to the registration roller 308 by the transport rollers 307 and 306.

  The image signal output from the control unit 400 is input to an optical scanning device 311 including a semiconductor laser and a polygon mirror. Further, the outer peripheral surface of the photosensitive drum 309 is charged by the charger 310. After the outer peripheral surface of the photosensitive drum 309 is charged, a laser beam corresponding to an image signal input to the optical scanning device 311 passes from the optical scanning device 311 via the polygon mirror and mirrors 312 and 313, and then the outer peripheral surface of the photosensitive drum 309. The surface is irradiated. As a result, an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 309.

  Subsequently, the electrostatic latent image is developed with toner in the developing device 314, and a toner image is formed on the outer peripheral surface of the photosensitive drum 309. The toner image formed on the photosensitive drum 309 is transferred to a sheet material by a transfer charger 315 provided at a position (transfer position) facing the photosensitive drum 309. In synchronization with this transfer timing, the registration roller 308 feeds the sheet material to the transfer position.

  As described above, the sheet material to which the toner image has been transferred is sent to the fixing device 318 by the conveyance belt 317, and is heated and pressed by the fixing device 318 to fix the toner image to the sheet material. In this way, an image is formed on the sheet material by the image forming apparatus 100.

  When image formation is performed in the single-sided printing mode, the sheet material that has passed through the fixing device 318 is discharged to a discharge tray (not shown) by discharge rollers 319 and 324. When image formation is performed in the duplex printing mode, after the fixing device 318 performs fixing processing on the first surface of the sheet material, the sheet material is discharged from the paper discharge roller 319, the conveyance roller 320, and the reverse roller 321. Is conveyed to the reverse path 325. Thereafter, the sheet material is conveyed again to the registration roller 308 by the conveyance rollers 322 and 323, and an image is formed on the second surface of the sheet material by the method described above. Thereafter, the sheet material is discharged to a discharge tray (not shown) by discharge rollers 319 and 324.

  When the sheet material image-formed on the first surface is discharged face-down outside the image forming apparatus 100, the sheet material that has passed through the fixing device 318 passes through the paper discharge roller 319 to the conveyance roller 320. Carry in the direction of heading. Thereafter, the rotation of the conveyance roller 320 is reversed immediately before the rear end of the sheet material passes through the nip portion of the conveyance roller 320. As a result, the sheet material is discharged to the outside of the image forming apparatus 100 via the paper discharge roller 324 with the first surface of the sheet material facing downward.

  FIG. 3 is a control configuration diagram of the image printing apparatus 301 according to the present embodiment. The control unit 151 includes a CPU 151a, a ROM 151b in which a control program is stored, and a RAM 151c that is used as an area for temporarily holding control data and a work area for operations associated with control. The control unit 151 is connected to the control unit 400, the operation unit 152, the analog / digital (A / D) converter 153, the high voltage control unit 155, the motor control unit 157, the sensors 159, and the AC driver 160. The control unit 151 can transmit and receive data and commands to and from each connected unit.

  The control unit 151 transmits setting value data of various apparatuses provided in the image printing apparatus 301 necessary for image processing in the document reading units 16 and 17 to the control unit 400. Furthermore, the control unit 151 receives a signal from the sensors 159 and sets a set value for the high-pressure control unit 155 based on the received signal. The high voltage control unit 155 supplies a necessary voltage to the high voltage unit 156 (charging device 310, developing device 314, transfer charging device 315, etc.) according to the set value set by the control unit 151.

  The motor control unit 157 controls the motor M6 by supplying a drive current to a winding of the motor M6 that drives a load provided in the image printing apparatus 301 in accordance with a signal output from the CPU 151a.

  The A / D converter 153 receives the detection signal detected by the thermistor 154 for detecting the temperature of the fixing heater 161, converts the detection signal from an analog signal to a digital signal, and transmits it to the control unit 151. The control unit 151 controls the AC driver 160 based on the digital signal received from the A / D converter 153. The AC driver 160 controls the fixing heater 161 so that the temperature of the fixing heater 161 becomes a temperature necessary for performing the fixing process. The fixing heater 161 is a heater used for fixing processing and is included in the fixing device 318.

  The control unit 151 controls the operation unit 152 so that an operation screen for the user to set the type of sheet material used for image formation is displayed on a display unit provided in the operation unit 152. The control unit 151 receives information set by the user from the operation unit 152 and controls an operation sequence of the image printing apparatus 301 based on the information set by the user. In addition, the control unit 151 transmits information indicating the state of the image forming apparatus 100 to the operation unit 152. The information indicating the state of the image forming apparatus 100 is, for example, information related to the number of images formed, the progress of the image forming operation, sheet material jams, double feeds, and the like in the document reading apparatus 201 and the image printing apparatus 301. The operation unit 152 displays the information received from the control unit 151 on the display unit. As described above, the control unit 151 controls the operation sequence of the image printing apparatus 301.

  Next, the configuration of the transport motor control unit 205 will be described. The carry motor control unit 205 in the present embodiment controls the carry motor M2 using vector control. In the present embodiment, the motor M2 is not provided with a sensor such as a rotary encoder for detecting the rotational phase of the rotor of the motor, but may be configured with a sensor.

  FIG. 4 is represented by a transport motor (hereinafter referred to as a motor) M2, which is a stepping motor composed of two phases of A phase (first phase) and B phase (second phase), and d-axis and q-axis. It is a figure which shows the relationship with a rotation coordinate system. In FIG. 4, an α axis that is an axis corresponding to the A phase winding and a β axis that is an axis corresponding to the B phase winding are defined in the stationary coordinate system. In FIG. 4, the d axis is defined along the direction of the magnetic flux created by the magnetic poles of the permanent magnets used in the rotor 402, and the direction is 90 degrees counterclockwise from the d axis (perpendicular to the d axis). The q-axis is defined along the direction of The angle formed by the α axis and the d axis is defined as θ, and the rotational phase of the rotor 402 is represented by the angle θ. In the vector control, a rotational coordinate system based on the rotational phase θ of the rotor 402 is used. Specifically, in the vector control, the current component in the rotating coordinate system of the current vector corresponding to the drive current flowing through the winding, and the q-axis component (torque current component) value for generating torque in the rotor, The d-axis component (excitation current component) value that affects the strength of the magnetic flux passing through the winding is used.

  Vector control is a motor that performs phase feedback control that controls the value of the torque current component and the value of the excitation current component so that the deviation between the command phase representing the target phase of the rotor and the actual rotation phase is small. It is the control method which controls.

  FIG. 5 is a block diagram illustrating an example of the configuration of the transport motor control unit 205 that controls the motor M2. As shown in FIG. 5, the conveyance motor control unit 205 is a circuit for performing vector control, and outputs a drive current to the phase controller 502, current controller 503, coordinate inverse converter 505, coordinate converter 511, and motor windings. A PWM inverter 506 to be supplied is included.

  The coordinate converter 511 represents the current vector corresponding to the drive current flowing through the A-phase and B-phase windings of the motor M2 from the stationary coordinate system represented by the α-axis and the β-axis by the q-axis and the d-axis. Convert to rotating coordinate system. As a result, the drive current flowing in the winding is represented by the current value of the q-axis component (q-axis current) and the current value of the d-axis component (d-axis current) that are current values in the rotating coordinate system. The q-axis current corresponds to a torque current that generates torque in the rotor 402 of the motor M2. The d-axis current corresponds to an excitation current that affects the strength of the magnetic flux passing through the winding of the motor M2, and does not contribute to the torque generation of the rotor 402. The conveyance motor control unit 205 can independently control the q-axis current and the d-axis current. As a result, the conveyance motor control unit 205 can efficiently generate the torque necessary for the rotor 402 to rotate by controlling the q-axis current according to the load torque applied to the rotor.

  The conveyance motor control unit 205 determines the rotational phase θ of the rotor 402 of the motor M2 by a method described later, and performs vector control based on the determination result. The CPU 401 generates a command phase θ_ref that represents the target phase of the rotor 402 of the motor M2, and outputs the command phase θ_ref to the transport motor control unit 205 at a predetermined time period.

  The subtractor 101 calculates the deviation between the rotational phase θ of the rotor 402 of the motor M 2 and the command phase θ_ref, and outputs the deviation to the phase controller 502. The phase controller 502 uses the q-axis current command value iq_ref and the d-axis so that the deviation output from the subtractor 101 becomes small based on proportional control (P), integral control (I), and differential control (D). A current command value id_ref is generated and output. Specifically, the phase controller 502 controls the q-axis current command value iq_ref and the d-axis current command value id_ref so that the deviation output from the subtractor 101 is 0 based on P control, I control, and D control. Is generated and output. The P control is a control method for controlling the value to be controlled based on a value proportional to the deviation between the command value and the estimated value. The I control is a control method for controlling the value to be controlled based on a value proportional to the time integral of the deviation between the command value and the estimated value. The D control is a control method for controlling the value to be controlled based on a value proportional to the time change of the deviation between the command value and the estimated value. The phase controller 502 in the present embodiment generates the q-axis current command value iq_ref and the d-axis current command value id_ref based on PID control, but is not limited to this. For example, the phase controller 502 may generate the q-axis current command value iq_ref and the d-axis current command value id_ref based on the PI control. When a permanent magnet is used for the rotor 402, the d-axis current command value id_ref that normally affects the strength of the magnetic flux passing through the winding is set to 0, but the present invention is not limited to this.

  The drive currents flowing in the A-phase and B-phase windings of the motor M2 are detected by current detectors 507 and 508, and then converted from analog values to digital values by the A / D converter 510.

The current value of the drive current converted from the analog value to the digital value by the A / D converter 510 is expressed by the following equation by the current vector phase θe shown in FIG. 4 as current values iα and iβ in the stationary coordinate system. expressed. The phase θe of the current vector is defined as an angle formed by the α axis and the current vector. I represents the magnitude of the current vector.
iα = I * cos θe (1)
iβ = I * sin θe (2)
These current values iα and iβ are input to the coordinate converter 511 and the induced voltage determiner 512.

The coordinate converter 511 converts the current values iα and iβ into the current value iq of the q-axis current and the current value id of the d-axis current in the rotating coordinate system by the following equation.
id = cos θ * iα + sin θ * iβ (3)
iq = −sin θ * iα + cos θ * iβ (4)
The current value iq converted by the coordinate converter 511 is input to the subtractor 102 and the CPU 401. The current value id converted by the coordinate converter 511 is input to the subtractor 103.

  The subtractor 102 calculates a deviation between the q-axis current command value iq_ref output from the phase controller 502 and the current value iq output from the coordinate converter 511, and outputs the deviation to the current controller 503. The subtractor 103 calculates a deviation between the d-axis current command value id_ref output from the phase controller 502 and the current value id output from the coordinate converter 511, and outputs the deviation to the current controller 503. .

  The current controller 503 generates drive voltages Vq and Vd based on PID control so that the deviations are reduced. Specifically, the current controller 503 generates drive voltages Vq and Vd so that the deviations become 0, and outputs them to the coordinate inverse converter 505. The current controller 503 in the present embodiment generates the drive voltages Vq and Vd based on PID control, but is not limited to this. For example, the current controller 503 may generate the drive voltages Vq and Vd based on PI control.

The coordinate inverse converter 505 inversely converts the drive voltages Vq and Vd in the rotating coordinate system output from the current controller 503 into the drive voltages Vα and Vβ in the stationary coordinate system according to the following equation.
Vα = cos θ * Vd−sin θ * Vq (5)
Vα = sin θ * Vd + cos θ * Vq (6)
The coordinate inverse converter 505 converts the drive voltages Vq and Vd in the rotating coordinate system into the drive voltages Vα and Vβ in the stationary coordinate system, and then outputs Vα and Vβ to the PWM inverter 506 and the induced voltage determiner 512.

  The PWM inverter 506 has a full bridge circuit. The full bridge circuit is driven by a PWM signal based on the drive voltages Vα and Vβ input from the coordinate inverse converter 505. As a result, the PWM inverter 506 generates drive currents iα and iβ corresponding to the drive voltages Vα and Vβ, and drives the motor M2 by supplying the drive currents iα and iβ to the windings of each phase of the motor M2. . In this embodiment, the PWM inverter has a full bridge circuit, but the PWM inverter may have a half bridge circuit or the like.

Next, a method for determining the rotational phase θ of the rotor will be described. For determining the rotational phase θ of the rotor, values of induced voltages Eα and Eβ induced in the A-phase and B-phase windings of the motor 509 by the rotation of the rotor are used. The value of the induced voltage is determined (calculated) by the induced voltage determiner 512. Specifically, the induced voltages Eα and Eβ are input from the A / D converter 510 to the induced voltage determiner 512 and the current values iα and iβ input from the coordinate inverse converter 505 to the induced voltage determiner 512. From the drive voltages Vα and Vβ, it is determined by the following equation.
Eα = Vα−R * iα−L * diα / dt (7)
Eβ = Vβ−R * iβ−L * diβ / dt (8)
Here, R is winding resistance, and L is winding inductance. The values of the winding resistance R and the winding inductance L are values specific to the motor M2 being used, and are stored in advance in a memory (not shown) provided in the ROM 402 or the conveyance motor control unit 205. The induced voltages Eα and Eβ determined by the induced voltage determiner 512 are output to the phase determiner 513.

The phase determiner 513 determines the rotational phase θ of the rotor 402 of the motor M2 based on the ratio of the induced voltage Eα and the induced voltage Eβ output from the induced voltage determiner 512 according to the following equation.
θ = tan ^ −1 (−Eβ / Eα) (9)
In the present embodiment, the phase determiner 513 determines the rotational phase θ by performing a calculation based on Expression (9), but this is not restrictive. For example, the phase determiner 513 rotates by referring to a table stored in the ROM 151b or the like and showing a relationship between the induced voltage Eα and the induced voltage Eβ and the rotational phase θ corresponding to the induced voltage Eα and the induced voltage Eβ. The phase θ may be determined.

  The rotor rotational phase θ obtained as described above is input to the subtractor 101, the coordinate inverse converter 505, and the coordinate converter 511. The transport motor control unit 205 repeatedly performs the above control.

  As described above, the transport motor control unit 205 according to the present embodiment performs vector control using phase feedback control that controls the current value in the rotating coordinate system so that the deviation between the command phase θ_ref and the rotating phase θ is small. . By performing the vector control, it is possible to suppress the motor from being stepped out, an increase in motor noise due to excess torque, and an increase in power consumption.

  FIG. 6 is a functional block diagram relating to feeding control and conveyance control by the CPU 401. As illustrated in FIG. 6, the current value iq output from the transport motor control unit 205 is input to the current comparison unit 2014 provided in the CPU 401. The current comparison unit 2014 detects a change in the current value iq and controls the feed motor control unit 204 based on the detection result. The feed motor control unit 204 drives the feed motor M1 as described below.

  Hereinafter, an example of document feeding and conveyance will be described with reference to FIG. Hereinafter, a document to be fed / conveyed is referred to as a document P, and a document fed / conveyed next to the document P is referred to as a document P ′.

  FIG. 7A shows a state where the document P is fed out by the pickup roller 3 and the leading end thereof reaches the nip portion of the separation feeding unit. The separation roller 5 comes into contact with the document P and rotates due to the frictional force with the document P. In FIG. 7A, the leading edge of the document P ′ does not reach the nip portion of the separation feeding unit.

  FIG. 7B shows a state in which the original P is conveyed by the rotation of the registration roller 6. When the document P is conveyed by the registration roller 6, the driving of the feeding motor M1 is stopped. As a result, the rotation of the pickup roller 3 and the feeding roller 4 stops. In FIG. 7B, since the document P is in contact with the feeding roller 4 and the separation roller 5, the feeding roller 4 and the separation roller 5 are rotated by a frictional force with the document P. That is, the feeding roller 4 and the separation roller 5 are rotated by a frictional force with the original P while the original P is being conveyed by the registration roller 6. In FIG. 7B, the leading edge of the subsequent document P ′ does not reach the nip portion of the separation feeding unit.

  FIG. 7C shows a state in which the trailing edge of the document P conveyed by the registration roller 6 has passed through the nip portion of the separation feeding unit. Since the feeding roller 4 and the separation roller 5 are not in contact with the original P, the rotation is stopped, and the feeding roller 4 and the separation roller 5 are stopped. In FIG. 7C, the leading edge of the document P ′ does not reach the nip portion of the separation feeding unit.

  Next, another example of document feeding and conveyance will be described with reference to FIG. 8A and 8B are the same as FIGS. 7A and 7B.

  8C, the state of the document P is the same as that in FIG. 8B, but shows the state at the moment when the leading edge of the document P ′ reaches the nip portion of the separation feeding unit. Since the document P ′ enters between the document P and the separation roller 5, the frictional force of the document P is not directly transmitted to the separation roller 5. Thereby, the rotation of the separation roller 5 is stopped.

  FIG. 8D shows a state where the original P ′ has moved slightly downstream from the state of FIG. 8C due to the frictional force between the original P and the original P ′. FIG. 8E shows a state immediately after the document P is conveyed by the registration roller 6 and its trailing edge has passed through the nip portion of the separation feeding unit. FIG. 8F shows the state shown in FIG. ) Shows a state in which the original P is slightly conveyed downstream.

  Next, a change in torque applied to the rotor of the conveyance motor M2 that drives the registration roller 6 will be described.

  7B and FIG. 8B, the preceding document P has a frictional force generated by the friction between the document P and the feeding roller 4 and a frictional force generated by the friction between the document P and the separation roller 5. Works in the direction opposite to the conveying direction. That is, the torque applied to the rotor of the conveyance motor M2 that drives the registration roller 6 is a torque corresponding to the friction force generated by the friction between the registration roller 6 and the document P, and the friction acting on the document P in the direction opposite to the conveyance direction. The torque corresponding to the force is added. Hereinafter, a state in which the document P is conveyed by the rotation of the registration roller 6 and the feeding roller 4 and the separation roller 5 are rotated by the frictional force with the document P is referred to as a state # 1. Further, the torque applied to the rotor of the conveyance motor M2 that drives the registration roller 6 in the state # 1 is referred to as a first torque.

  On the other hand, in the state shown in FIG. 7C, the preceding document P is conveyed by the registration roller 6, but the trailing edge of the document P passes through the nip portion of the separation feeding unit and the separation roller 4 and the separation roller 6 are separated. The rotation of the roller 5 is stopped. At this time, the torque applied to the rotor of the conveyance motor M2 that drives the registration roller 6 is only the torque corresponding to the frictional force generated by the friction between the registration roller 6 and the document P. Hereinafter, a state in which the document P is conveyed by the rotation of the registration roller 6 and the feeding roller 4 and the separation roller 5 are stopped is referred to as a state # 2. Further, the torque applied to the rotor of the conveyance motor M2 that drives the registration roller 6 in the state # 2 is referred to as a second torque.

  Further, in the state of FIG. 8D, the preceding document P has a frictional force generated by the friction between the document P and the feeding roller 4 and a frictional force generated by the friction between the document P and the document P ′ in the transport direction. Work in the opposite direction. The rotation of the separation roller 5 is stopped by the leading edge of the subsequent document P ′ entering the nip portion of the separation feeding unit. At this time, the torque applied to the rotor of the transport motor M2 that drives the registration roller 6 acts on the document P in a direction opposite to the transport direction to a torque corresponding to the frictional force generated by the friction between the registration roller 6 and the document P. The torque corresponding to the frictional force is added. In the following, state # 3 is a state in which the separation roller 5 is stopped because the document P is conveyed by the rotation of the registration roller 6 and the leading edge of the subsequent document P ′ enters the nip portion of the separation feeding unit. Shall be called. Further, the torque applied to the rotor of the conveyance motor M2 that drives the registration roller 6 in the state # 3 is referred to as a third torque. Note that the frictional force generated by the friction between the original P and the original P ′ is smaller than the frictional force generated by the friction between the original P and the separation roller 5. Therefore, the third torque is smaller than the first torque.

  From the above, among the first torque, the second torque, and the third torque, the first torque is the largest value, the second torque is the smallest value, and the third torque is the first torque and the second torque. It becomes a value between.

  The state shown in FIG. 8F is a state where the trailing edge of the document P has passed through the nip portion of the separation feeding unit. At this time, the torque applied to the rotor of the conveyance motor M2 that drives the registration roller 6 is the same as the second torque in FIG. However, the state of FIG. 8F is a state transitioned from the state # 3, and the document P ′ is nipped in the nip portion of the separation feeding unit. In the following, as shown in FIG. 8F, the rear end of the document P passes through the nip portion of the separation feeding unit, and the document P ′ nipped in the nip portion of the separation feeding unit overlaps the document P. The state that is not present is referred to as state # 4.

  The current comparison unit 2014 in the present embodiment determines whether the document P and the document P ′ are in the state # 1 to the state # 4 based on the current value iq acquired from the transport motor control unit 204. Hereinafter, a method in which the current comparison unit 2014 determines the states of the document P and the document P ′ based on the current value iq will be described. In the following description, a value smaller than the value of the torque current component corresponding to the first torque and larger than the value of the torque current component corresponding to the third torque is set as the first threshold value isth1. Further, a value smaller than the value of the torque current component corresponding to the third torque and larger than the value of the torque current component corresponding to the second torque is set as the second threshold value isth2. The second threshold value isth2 is set to a value such that the current value iq does not fall below the second threshold value itth2 when the original P is being conveyed with the next original P ′ and the original P being overlapped.

  9 and 10 are diagrams showing the relationship among the current value iq, the first threshold value ith1, and the second threshold value ith2. As shown in FIG. 9, the current comparison unit 2014 determines that the state of the document P and the document P ′ is the state # 1 when the input current value iq is equal to or greater than the first threshold value isth1. Thereafter, when the state in which the input current value iq is smaller than the first threshold value isth1 and is equal to or larger than the second threshold value isth2 is smaller than the second threshold value isth2 without continuing for a predetermined time T1, the current comparison unit 2014 It is determined that the state of the document P and the document P ′ has transitioned from state # 1 to state # 2.

  On the other hand, as shown in FIG. 10, after determining that the state is # 1, the state where the input current value iq is smaller than the first threshold value isth1 and is equal to or larger than the second threshold value ish2 continues for a predetermined time, that is, If it continues for the time T1, the current comparison unit 2014 determines that the state of the document P and the document P ′ has transitioned from state # 1 to state # 3. Thereafter, when the input current value iq becomes a value smaller than the second threshold value isth2, the current comparison unit 2014 determines that the state of the document P and the document P ′ has transitioned from the state # 3 to the state # 4. Note that the predetermined time T1 is longer than the time taken for the states of the original P and the original P ′ to change from the state # 1 to the state # 2 in FIG. 9, and the original P and the original P ′ in FIG. It is set to a time shorter than the time during which the state is continued.

  FIG. 11 is a flowchart of feeding control in the image forming apparatus 100. The process of this flowchart is executed by the CPU 401. After the sheet conveyance is instructed, in S101, the CPU 401 determines whether or not a document is stacked on the paper feed tray 2 based on the output of the document set sensor SS1. If the document is not stacked on the paper feed tray 2, the CPU 401 ends the process of this flowchart. On the other hand, if the document is stacked on the paper feed tray 2, the CPU 401 starts feeding and transporting the document by the transport motors M1 and M2 in S102.

  Next, in S103, when the current value iq is equal to or greater than the first threshold value isth1, the CPU 401 advances the process to S104. Thereafter, in S104, when the current value iq is smaller than the first threshold value ith1 and not equal to or larger than the second threshold value ith2, the CPU 401 advances the process to S105. If the current value iq is not smaller than the second threshold value isth2 in S105, the CPU 401 repeats the process from S104. On the other hand, if the current value iq is smaller than the second threshold value isth in S105, the CPU 401 advances the process to S106. In S106, it is determined based on the output of the document set sensor SS1 whether or not the next document is stacked on the paper feed tray 2. If the next original is not stacked on the paper feed tray 2, the CPU 401 ends the processing of this flowchart. On the other hand, when the next original is stacked on the paper feed tray 2, the CPU 401 repeats the processing from S102.

  On the other hand, if the current value iq is smaller than the first threshold value ith1 and greater than or equal to the second threshold value ith2 in S104, the CPU 401 advances the process to S107. In S107, when the state where the current value iq is smaller than the first threshold value ith1 and equal to or larger than the second threshold value ith2 does not continue for the predetermined time T1, the CPU 401 advances the process to S105. In S107, when the current value iq is smaller than the first threshold value ith1 and is equal to or larger than the second threshold value ith2, the CPU 401 advances the process to S108.

  After that, when the current value iq becomes smaller than the second threshold value isth2 in S108, the CPU 401 determines in S109 whether the document detection sensor SS2 is OFF, that is, whether the document detection sensor SS2 has detected the document. Note that the document detection sensor SS2 does not detect the document in S109 because the trailing edge of the document P to be fed is on the downstream side in the transport direction from the document detection sensor SS2, and the leading edge of the next document P ′ is It means that it is on the upstream side in the conveyance direction with respect to the document detection sensor SS2. That is, there is an interval between the document P to be fed and the next document P ′.

  If the document detection sensor SS2 does not detect a document in S109, the CPU 401 determines in S106 whether there is a next document. If there is a next document, the CPU 401 feeds the next document in S102. Start. In this case, the next document is a document that is nipped in the nip portion of the separation feeding unit.

  On the other hand, if the document detection sensor SS2 detects a document in S109, the CPU 401 advances the process to S110.

  In S110, when the predetermined time T2 has not elapsed since the current value iq has become smaller than the second threshold value isth2, the CPU 401 repeats the processing from S109. Note that the elapse of the predetermined time T2 in S110 means that the next original P ′ is detected by the original detection sensor SS2. Further, since the current value iq is smaller than the second threshold value isth2, there is no overlap between the preceding document P and the next document P ′. Accordingly, when the predetermined time T2 has elapsed in S110 and there is a next original in S106, the CPU 401 starts feeding the next original. Here, the next document is a document P ′ that is nipped in the nip portion of the separation feeding unit and detected by the document detection sensor SS2. When the sheet conveyance is instructed, the CPU 401 repeatedly performs the above-described processing.

  As described above, in the present embodiment, the feeding of the sheet material is controlled based on the current value iq. Specifically, when the current value iq changes from a value greater than or equal to a predetermined value (second threshold value isth2) to a value smaller than the predetermined value, if there is a next original P ′, the next original P ′ is fed. To start. More specifically, the current value iq is changed from a value greater than or equal to the first threshold value ith1 to a value smaller than the first threshold value ith1 and smaller than the second threshold value ith2 without continuing for a predetermined time T1. Then, the CPU 401 determines that the trailing edge of the document P has passed through the separation feeding unit. In this case, if there is a next document P ′, the CPU 401 starts feeding the next document P ′.

  On the other hand, when the current value iq continues from the value equal to or greater than the first threshold value ith1 to a value smaller than the first threshold value ith1 and equal to or greater than the second threshold value ith2 for a predetermined time T1, the CPU 401 reads It is determined that P and the next original P ′ are nipped in the nip portion of the separation feeding unit. The document P to be fed is conveyed by the registration roller 6. Thereafter, when the current value iq becomes smaller than the second threshold value itth2, the CPU 401 eliminates the overlap between the document P to be fed and the next document P ′, and the trailing edge of the document P to be fed is separated and fed. Is determined to have passed through the nip portion. Note that it can be determined that there is no overlap because the current value iq does not fall below the second threshold value isth2 when the next original P ′ is moved by the frictional force with the original P to be fed.

  In this case, when the document detection sensor SS2 no longer detects the document P, the CPU 401 starts feeding the next document P ′. That the document detection sensor SS2 does not detect the document is that the trailing edge of the document P to be fed is on the downstream side in the transport direction from the document detection sensor SS2, and the leading edge of the next document P ′ is from the document detection sensor SS2. This also means that it is located upstream in the transport direction. Also, when the predetermined time T2 has elapsed since the current value iq has become smaller than the second threshold value isth2, the CPU 401 starts feeding the next document P ′. By waiting for the predetermined time T2, it is possible to secure an interval between the document P to be fed and the next document P ′. As a result, it is possible to suppress the occurrence of jam even when the feeding of the next original P ′ is started.

  As described above, in this embodiment, it is determined based on the value of the torque current component that the document to be fed has passed through the separation feeding unit. Further, based on the value of the torque current component, it is detected that the document P to be fed and the next document P ′ are in the double feed state at the nip portion of the separation feed unit and the double feed state is eliminated. Is done. By detecting the cancellation of the double feeding state, the feeding timing of the next document P ′ is appropriately determined. As described above, the configuration according to the present embodiment can shorten the interval between a plurality of sheets fed and conveyed.

  In the present embodiment, the feeding control is performed based on the current value iq, but this is not restrictive. For example, feeding control may be performed based on the q-axis current command value iq_ref.

  Further, the feeding control may be performed based on the load torque T applied to the rotor of the motor M2. The load torque T is determined based on, for example, the deviation between the rotational phase θ of the rotor 402 and the command phase θ_ref. Further, the load torque T may be determined based on a table stored in advance in the ROM 402 and indicating the relationship between the current value iq and the load torque T.

  In the present embodiment, the separation roller 5 is used as a separation member for separating the fed sheet material, but the present invention is not limited to this. For example, a separation pad or the like may be used.

  In this embodiment, a stepping motor is used as a motor for driving a load, but another motor such as a DC motor may be used. The motor is not limited to a two-phase motor, and may be another motor such as a three-phase motor. Moreover, although the conveyance motor control part in this embodiment controls the motor M2 by performing phase feedback control, it is not limited to this. For example, the configuration of the transport motor control unit may be a configuration that controls the motor M2 by feeding back the rotational speed ω of the rotor 402. Specifically, as shown in FIG. 12, the speed controller 500 provided in the transport motor controller has a small deviation between the command speed ω_ref representing the target speed of the rotor output from the CPU 401 and the rotational speed ω. The q-axis current command value iq_ref and the d-axis current command value id_ref are generated and output as described above. A configuration in which the motor M2 is controlled by performing such speed feedback control may be employed. The rotational speed ω is determined by the speed determiner 514 based on the temporal change of the rotational phase θ.

  2: Paper feed tray, 3: Pickup roller, 4: Feed roller, 5: Separation roller, 12: Peristaltic arm, 6: Registration roller, 205: Conveyance motor controller, 401: CPU

Claims (10)

A loading means for loading the sheet material;
A feeding means for feeding the sheet material loaded on the loading means;
A conveyance roller that is provided downstream of the feeding unit in the conveyance direction in which the sheet material is conveyed, and conveys the sheet material fed by the feeding unit to the downstream side in the conveyance direction;
A motor for driving the transport roller;
Phase determining means for determining the rotational phase of the rotor of the motor;
A current component of a drive current flowing in the winding of the motor, expressed in a rotational coordinate system based on the rotational phase determined by the phase determining means, and generating a torque in the rotor of the motor Control means for controlling the drive current flowing in the winding of the motor based on the value of and the value of the excitation current component affecting the strength of the magnetic flux passing through the winding of the motor;
With
In the feeding unit, a value of a torque current component of the driving current flowing in the winding of the motor in a state where the feeding roller is feeding the first sheet material fed by the feeding unit is a predetermined value or more. The sheet conveying apparatus starts feeding the second sheet material to be fed next to the first sheet material when the value is changed from the value to a value smaller than the predetermined value.   The feeding means has a torque current component value of the driving current flowing in the winding of the motor in a state where the conveying roller is conveying the first sheet material, a second predetermined value larger than the predetermined value. When the value of the torque current component changes from a value equal to or greater than the predetermined value to a value smaller than the predetermined value without continuing the state that is smaller and equal to or greater than the predetermined value for a predetermined time, the feeding of the second sheet material The sheet conveying apparatus according to claim 1, wherein the sheet conveying apparatus is started. The sheet conveying apparatus includes a detecting unit that detects the sheet material between the feeding unit and the conveying roller.
The feeding means has a torque current component value of the driving current flowing in the winding of the motor in a state where the conveyance roller is conveying the first sheet material and is smaller than the second predetermined value and the predetermined value. After the state having been described above continues for the predetermined time, when the value of the torque current component changes to a value smaller than the predetermined value and the detection means has not detected the sheet material, the second sheet material The sheet conveying apparatus according to claim 2, wherein the feeding of the sheet is started. The feeding means is
A pickup roller for feeding the sheet material stacked on the stacking means;
A feeding roller that further feeds the sheet material fed by the pickup roller;
A separation member that configures the nip portion with the feeding roller, and separates a plurality of sheet materials conveyed in the overlapped state with the feeding roller at the nip portion;
With
The predetermined value is a second torque corresponding to a load torque applied to the rotor of the motor when the conveying roller conveys the first sheet material in a state where the first sheet material is not nipped at the nip portion. When the transport roller transports the first sheet material in a state in which the first sheet material and the second sheet material are overlapped and nipped in the nip portion, the current roller is larger than the current component value. The sheet conveying apparatus according to claim 2, wherein the sheet conveying apparatus is smaller than a value of a third torque current component corresponding to a load torque applied to the rotor. When the conveying roller conveys the first sheet material, the driving of the feeding roller is stopped,
The second predetermined value is set such that the first sheet material is nipped at a nip portion between the feeding roller and the separating member in a stopped state, and the transport roller is in the state where the second sheet material is not nipped. 5. A value of a fourth torque current component corresponding to a load torque applied to a rotor of the motor when a sheet material is conveyed is greater than a value of the third torque current component. The sheet conveying apparatus according to 4. The separation member is a separation roller that forms a nip portion with the feeding roller,
The separation roller is rotated by friction with the sheet material conveyed by the conveyance roller while the sheet material conveyed by the conveyance roller is nipped by the nip portion. 5. The sheet conveying apparatus according to 5.   The sheet conveying apparatus according to claim 4, wherein the driving of the feeding roller is synchronized with the driving of the pickup roller. The sheet conveying apparatus is
Current detection means for detecting the drive current flowing in the winding of the motor;
Conversion means for converting a current value of the stationary coordinate system of the driving current detected by the current detection means into a current value of the rotational coordinate system based on the rotational phase determined by the phase determination means;
With
8. The feeding device according to claim 1, wherein the feeding unit starts feeding the second sheet material based on a torque current component of the current value of the rotating coordinate system converted by the converting unit. The sheet conveying apparatus according to claim 1. A loading means for loading a document;
A feeding means for feeding a document loaded on the loading means;
A transport roller provided downstream of the feeding unit in the transport direction in which the document is transported, and transports the document fed by the feed unit to the downstream side of the transport direction;
Reading means for reading the document conveyed by the conveyance roller;
A motor for driving the transport roller;
Phase determining means for determining the rotational phase of the rotor of the motor;
A current component of a drive current flowing in the winding of the motor, expressed in a rotational coordinate system based on the rotational phase determined by the phase determining means, and generating a torque in the rotor of the motor Control means for controlling the drive current flowing in the winding of the motor based on the value of and the value of the excitation current component affecting the strength of the magnetic flux passing through the winding of the motor;
With
In the feeding unit, a value of a torque current component of the driving current flowing in the winding of the motor in a state where the feeding roller is feeding the first sheet material fed by the feeding unit is a predetermined value or more. The document reading apparatus is characterized in that when the first sheet material changes to a value smaller than the predetermined value, feeding of the second sheet material to be fed next to the first sheet material is started. A loading means for loading the sheet material;
A feeding means for feeding the sheet material loaded on the loading means;
A conveyance roller that is provided downstream of the feeding unit in the conveyance direction in which the sheet material is conveyed, and conveys the sheet material fed by the feeding unit to the downstream side in the conveyance direction;
Image forming means for forming an image on the sheet material conveyed by the conveyance roller;
A motor for driving the transport roller;
Phase determining means for determining the rotational phase of the rotor of the motor;
A current component of a drive current flowing in the winding of the motor, expressed in a rotational coordinate system based on the rotational phase determined by the phase determining means, and generating a torque in the rotor of the motor Control means for controlling the drive current flowing in the winding of the motor based on the value of and the value of the excitation current component affecting the strength of the magnetic flux passing through the winding of the motor;
With
In the feeding unit, a value of a torque current component of the driving current flowing in the winding of the motor in a state where the feeding roller is feeding the first sheet material fed by the feeding unit is a predetermined value or more. The image forming apparatus according to claim 1, wherein when the first sheet material is changed to a value smaller than the predetermined value, feeding of the second sheet material to be fed next to the first sheet material is started.

Images