JP2006290562A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device reducing generation of vibration and noise and reducing electric power consumption. <P>SOLUTION: The image forming device comprises a sheet material conveyance member for conveying sheet material, a conveyance member drive means for driving the sheet material conveyance member and a vibration detection means for detecting vibration of the sheet material conveyance member and changes driving current of the conveyance member drive means based on the vibration of the vibration detection means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention includes a conveying member that conveys a sheet and a driving unit that drives the conveying member, detects the conveyance state of the sheet by detecting vibration of the driving member, and changes the control of the driving unit according to the conveying state. The present invention relates to an image forming apparatus such as a copying machine or a printer provided with a means for performing the above.

Conventionally, there is Patent Document 1 that changes the control of the driving means by detecting vibration. This relates to a so-called panning type document conveying apparatus that reads an image with an image reading apparatus while conveying an original or recording paper at a constant speed with a roller driven by a stepping motor. In this document conveying device, a stepping motor that drives a roller that conveys a document on the reading position of the image reading device, a detection unit that detects vibration of the stepping motor, and a signal detected by the detection unit are amplitude and frequency And a control means for gradually reducing the drive current of the stepping motor when it is determined that the vibration level affects the image reading and / or the generation of noise. By gradually reducing the drive current, the torque of the stepping motor is reduced and vibration is reduced. As a result, motor vibration and minute fluctuations in the conveyance speed are suppressed, and image reading disturbance and noise generation are eliminated.
JP-A-10-109780

  The current stepping motor sets the drive current by adding an appropriate amount of margin to the maximum load torque in order to prevent step-out due to load fluctuations. However, vibration and noise are generated due to excessive torque at low loads. However, in the method of controlling the drive current by detecting the vibration of the stepping motor itself, which is the driving means, as described above, the vibration that affects the conveying member due to the vibration caused by the motor itself. Effective, but effective control for load-side factors such as vibrations that affect transport members due to factors other than motors, such as the type of sheet material to be transported, wear of transport rollers, and backlash of drive gear There was a problem that could not be done.

  Therefore, in the present invention, the vibration of the conveying member that conveys the sheet is detected, and the control of the driving unit that drives the conveying member is changed based on the detection result, thereby reducing the generation of vibration and noise and further reducing the consumption. An object of the present invention is to provide an image forming apparatus capable of reducing power.

  The present invention is an image forming apparatus having the following configuration.

  (1) A sheet material conveying member that conveys a sheet material, a conveying member driving unit that drives the sheet material conveying member, and a vibration detecting unit that detects vibration of the sheet material conveying member, the vibration of the vibration detecting unit And changing the driving current of the conveying member driving means.

  (2) A sheet material conveying member that conveys the sheet material, a conveying member driving unit that drives the sheet material conveying member, and a vibration detecting unit that detects vibration of the sheet material conveying member, and the vibration of the vibration detecting unit And changing the excitation method of the conveying member driving means.

  (3) The image forming apparatus according to (1) or (2), wherein the sheet material conveying member is a conveying roller.

  (4) The image forming apparatus according to (1) or (2), wherein the conveying member driving unit is a stepping motor.

  (5) The image forming apparatus according to (1) or (2), wherein the timing for controlling the driving current of the conveying member driving unit is between sheets.

  (6) The image forming apparatus according to (1) or (2), wherein the timing for controlling the driving current of the conveying member driving unit is between JOBs.

  (7) The image forming apparatus according to (1) or (2), wherein the vibration detecting unit is an acceleration sensor.

  According to the present invention, it is possible to provide a device that can reduce generation of vibration and noise and can further reduce power consumption.

  Embodiments of an image forming apparatus and an image formation control method according to the present invention will be described with reference to the drawings.

[First embodiment]
(overall structure)
FIG. 1 is an internal configuration diagram of an image forming apparatus to which the sheet conveying apparatus according to the first embodiment is applied.

  The image forming apparatus includes a main body image output unit 10 that forms and outputs a document image on a sheet sheet, a main body image input unit 11 that reads image data from the document, and a main body image input unit 11. An automatic document feeder 12 mounted on the upper part and a sorter 13 for sorting and discharging image-formed sheet sheets discharged from the main body image output unit 10 into a plurality of discharge trays 45 are provided. .

  This image forming apparatus is a digital copying machine. For this reason, the image formed by the main body image output unit 10 is pixelated from the original by the CCD of the main body image input unit 11 and read into the apparatus as image data, and after necessary image processing is performed, it is stored in the image memory. The image data is transferred to the main body image output unit 10, and the image is reproduced to form an image on a sheet.

  The main body image input unit 11 includes a light source 21 that scans while irradiating a document placed on a document table on the upper surface of the main body image input unit 11. The light source 21 obtains driving force from an optical system motor (not shown) and reciprocates in the left-right direction in FIG. The light generated from the light source 21 is reflected by the stacked originals to obtain an optical image. This optical image is transmitted to the CCD 26 via the mirrors 22, 23 and 24 and the lens 25. Further, the mirrors 22, 23 and 24 are driven integrally with the light source 21. The CCD 26 is composed of an element that converts light into an electric signal, and an optical image transmitted by the function of the element is converted into an electric signal and further converted into a digital signal (image data).

  The read image data of the original is subjected to various correction processes and image processes desired by the user, and is stored in an image memory (not shown).

  The main body image output unit 10 reads the image data stored in the image memory, reconverts the digital signal into an analog signal, and further amplifies the output value to an appropriate output value by an exposure control unit (not shown). Converted to a signal. The optical signal propagates through the scanner 28, the lens 29, and the mirror 30 and is irradiated onto the photosensitive drum 31 to form an electrostatic latent image.

  This latent image becomes an image developed with toner, and the developed image is transferred onto a sheet conveyed through the main body. Further, the sheet is conveyed, and the toner on the sheet is fixed by the fixing roller 32 to form an image. And the image data is recorded on the sheet and sent to the sorter 13.

  The sorter 13 is an apparatus installed on the left side of the main body image output unit 10, and performs a process of sorting and discharging the image-formed sheets output from the main body image output unit 10 into a plurality of discharge trays 45. Do. The paper discharge tray 45 is controlled by a main body control unit (not shown), and the output sheet is discharged to an arbitrary paper discharge tray 45 instructed by the main body control unit.

  The paper feed trays 34 and 35 are located at the lower part of the main body, and can store sheets for forming images to some extent. The main body control unit conveys the accumulated sheets from the paper feed trays 34 and 35 and forms an image on the conveyed sheets.

  The paper feed deck 36 is a device installed on the right side of the main body image output unit 10 and can store a large amount of sheets. As with the paper feed trays 34 and 35, the sheets accumulated by the main body control unit are conveyed, and an image is formed on the conveyed sheets.

  On the right side of the main body image output unit 10, a manual feed tray 37 that allows an operator to feed a small number of arbitrary types of sheets relatively easily is installed. The manual feed tray 37 is also used when a special sheet such as an OHP sheet, cardboard, or postcard size paper is used.

  When transferring an image from the photosensitive drum 31 onto the sheet, the registration roller 33 abuts the conveyed sheet against the registration roller 33, temporarily stops, and then transports the sheet to the image forming unit again. ing. Due to the above-described operation of the registration roller 33, the conveyance timing of the leading edge of the sheet is adjusted, and the registration roller 33 is controlled to start driving in synchronization with the formation of the latent image on the photosensitive drum 31. It is possible to form an image with less. When the sheet is conveyed from the registration roller 33 to the image forming unit, the sheet is conveyed at an image forming speed different from the normal sheet conveying speed.

  Conveying rollers 38, 39, 40, 41, 42, 43, and 44 as conveying means are provided on a sheet conveying path in the main body, and the conveying rollers 38, 39, 40, 41, 42, 43, and 44 are provided. Plays a role of actually transporting the sheet when feeding the image forming process. Each of the transport rollers 38, 39, 40, 41, 42, 43, 44 is independently connected to a stepping motor as a driving means via a transmission device such as a gear, and each stepping motor can be directly operated and stopped. Each stepping motor drives each conveyance roller 38, 39, 40, 41, 42, 43, 44 so as to be in an operating state.

  FIG. 2 shows a schematic configuration of drive control of a stepping motor that drives these transport rollers 38, 39, 40, 41, 42, 43, and 44. In the following, since all of the transport rollers 38, 39, 40, 41, 42, 43, 44 are the same, the transport rollers will be described without being numbered.

(Motor drive control)
FIG. 2 is a block diagram for performing motor control and vibration detection control in this embodiment. Here, the motor control will be described first, and the vibration detection control will be described later. Motor control mainly performs chopping control, variable control of current setting, and rotation speed control of the motor. In the drive circuit 403, constant current chopping control is configured by hardware, and the current supplied to the stepping motor 201 is turned on / off in accordance with the phase excitation signal output from the rotation speed variable control unit 412 included in the CPU 402. The chopping control is performed so that the current flowing through the motor becomes a constant current, and the current is supplied to the stepping motor 201. The drive circuit 403 includes a current setting circuit 411 for performing chopping control. In the present embodiment, at least two or more levels of current setting values can be controlled, and current setting is performed. The control signal is output from the CPU.

  The ROM 407 is a nonvolatile storage device. The ROM device 407 stores a motor control program, and the program is loaded into the CPU 402 as necessary. The SRAM 408 is a rewritable storage device for storing calculation results and temporarily saving calculation results when the CPU 402 performs calculations. In recent years, there are CPUs in which ROM and RAM are integrated in the same package as the CPU. When such a CPU is used, the ROM 407 and the SRAM 408 can be omitted.

  The detailed contents of the rotation speed variable control unit 412 related to the variable control of the rotation speed of the motor will be described with reference to FIG. The TCU (timer count unit) 602 includes a timer, counts the clock CLK, and outputs a single pulse PPS-CK when the count reaches a value set in the timer.

  In the CPU 402, in the gate array, or in the external SRAM 408, data corresponding to motor acceleration and steady rotational speed is stored. The ARBITER 604 is a control unit having a role of permitting and distributing the access right according to a predetermined priority order when the SRAM 408 is used as a shared memory. The DMAC is a control unit that performs a direct memory access function. The pattern generator 603 is a control unit that generates a pulse signal for each phase of the motor.

  Using the DMAC 601 built in the CPU 402 or a custom IC such as a gate array, the data on the SRAM 408 is read and a counter value is set for the TCU 602. When the ARBITER 604 receives a DREQ request signal when accessing the SRAM 408, it returns a DACK and permits access to the SRAM 408 when control can be performed according to an agreement such as priority. Further, the CPU 402 sets the start address and end address of the data on the SRAM 408 in the DMAC 601, and the DMAC 601 sets the data in the set address space in the read TCU 602.

  Here, DMA-UP / DOWN for controlling the trigger signal DMA-EXEC signal for executing the DMAC 601 and the case of setting the TCU 602 while incrementing the address space on the SRAM 408 and the case of setting the TCU 602 while decrementing. The CPU 402 controls the signal. By switching the DMA-UP / DOWN signal between acceleration and deceleration, the same data can be used and the data amount of the SRAM 408 can be saved.

  The TCU 602 is, for example, an up-count timer, and the DMAC 601 sets a value to be set in the compare device with a CMP signal, and the timer counts up until that value is reached. When counting up to the set compare value, PPA-CK is output to the pattern generator 603 as a compare match signal. Thereafter, the DMAC 601 reads the data to be set next in the compare unit from the SRAM 408 and sets it in the TCU 602. Further, the CLK input to the TCU 602 may be variably controlled. The pattern generator 603 is a shift register, and shifts the pattern bit by bit to the output stage by the input signal PPS-CK and outputs it.

  The interval for shifting is governed by PPS-CK. When the interval of PPS-CK is gradually narrowed, the motor performs an acceleration operation. Conversely, when the interval between PPS-CK is gradually increased, the motor performs a deceleration operation. When the interval of PPS-CK is constant, the motor performs a constant speed operation.

  When driving a four-phase stepping motor, if there are four shift registers and a pattern shifted in phase by an amount corresponding to one step is set as the initial value of each register, the A phase, A * phase, B phase, B * A phase output signal can be obtained.

  FIG. 4 is a diagram illustrating a detailed structure of a sheet conveying system as a sheet conveying device in the image forming apparatus according to the present embodiment. Here, since the same applies to all of the conveyance rollers 38, 39, 40, 41, 42, 43, and 44, these numbers are not assigned to the conveyance rollers, and 71 is arranged upstream in the sheet conveyance direction. The first conveyance roller 72 is a second conveyance roller disposed on the downstream side of the first conveyance roller 71 in the sheet conveyance direction, and the operation will be mainly described with respect to the second conveyance roller 72. Reference numeral 62 denotes a stepping motor that drives the first transport roller 71, and 63 denotes a stepping motor that drives the second transport roller 72.

  81 is a sheet detection sensor and 82 is a photo interrupter. The sheet sheet detection sensor 81 and the photo interrupter 82 constitute sheet detection means. Reference numeral 91 denotes a first sheet, and reference numeral 92 denotes a second sheet conveyed next to the first sheet 91.

  In the sheet conveyance system shown in FIG. 4, the sheet is conveyed in the direction from the first conveyance roller 71 to the second conveyance roller 72. When the sheet is transported and the leading edge of the sheet passes over the sheet detection sensor 81, the sheet detection sensor 81 and the photo interrupter 82 block the light receiving unit of the photo interrupter 82 and change depending on the state of the light receiving unit. The signal is transmitted to the control unit, and the main body control unit can determine whether or not the sheet exists on the sheet detection sensor 81 by the above-described electric signal.

  In the present embodiment, the leading edge of the sheet that has passed through the first conveyance roller 71 passes the sheet detection sensor 81, and the second conveyance roller 72 is based on the timing when the electrical signal of the photo interrupter 82 enters the sheet presence state. The stepping motor 63 for driving is started.

  The second conveying roller 72 is stopped on the basis of the timing at which the trailing edge of the sheet being conveyed passes through the above-described sheet detection sensor 81 and the electrical signal of the photo interrupter 82 becomes in the absence of the sheet. The stepping motor 63 that drives the conveying roller 72 is stopped.

  As shown in FIG. 3, when the sheet is continuously conveyed by the sheet conveyance system in the present embodiment, the timing at which the trailing edge of the first sheet 91 conveyed in advance passes through the sheet detection sensor 81. Accordingly, the stepping motor 63 that drives the second conveying roller 72 is decelerated and stopped, and the stepping motor 63 is started based on the timing at which the leading edge of the second sheet 92 passes the sheet detection sensor 81.

(Vibration detection control)
FIG. 5 is a diagram illustrating a configuration of a sheet conveyance path that detects vibration of a conveyance roller that conveys a sheet material.

  In the figure, 31 is a photosensitive drum for forming an image. A registration clutch (registration roller) 33 determines the sheet feeding timing. Reference numeral 53 denotes a paper sensor (hereinafter referred to as a registration sensor) that detects the conveyed paper, and is provided on the side opposite to the photosensitive drum 31 with respect to the registration clutch 33. Reference numerals 42a and 42b denote conveyance rollers for conveying the sheet, and reference numeral 54 denotes a sheet detection sensor. Reference numeral 51 denotes an acceleration sensor for detecting vibrations of the transport rollers 42a and 42b. Reference numeral 52 denotes a contact member for transmitting the vibration of the conveying roller to the acceleration sensor 51 and also serves as a holding mechanism for holding the acceleration sensor 51.

  FIG. 6 is a diagram illustrating in detail the arrangement of the acceleration sensor 51 that detects the vibration of the conveyance roller that conveys the sheet material. As shown in FIG. 3, the motor 201 is driven through a gear 202. The motor 201 is a stepping motor, and can easily perform variable control of the recording paper conveyance speed by the conveyance rollers 42a and 42b. A feature of the stepping motor is that it rotates in response to pulse power. In addition, since the rotation angle is displaced in proportion to the number of input pulses and the rotation speed is displaced in proportion to the input frequency, the motor can be driven without forming a feedback loop. Because of these features, it is widely used as a drive source for open-loop positioning control and speed control.

  In this embodiment, a two-phase excitation type HR stepping motor is employed. In the HR stepping motor, the rotor part is composed of a gear-shaped iron core and a magnet.

  Further, as shown in the figure, the acceleration sensor 51 is held by the contact member 52, and the contact member 52 is configured to detect the vibration of the transport roller 42b.

  Next, the internal block configuration of the acceleration sensor 51 will be described with reference to FIG. 7, and the operation principle will be described with reference to FIG. The acceleration sensor 51 is a converter that changes vibration and the like into an electrical quantity, and there are various types. Typical examples include a capacitive acceleration sensor, a piezoelectric acceleration sensor, and the like. This embodiment will be described using a capacitance type acceleration sensor. As a suitable example, an acceleration sensor manufactured by Analog Devices will be described.

  The sensor is constructed on a silicon wafer with a surface micromachined polysilicon structure as shown in FIG. The structure is supported on the wafer surface by a polysilicon spring to resist the force generated by acceleration. The deflection of this structure is measured using a differential capacitor consisting of a plurality of independent fixed plates and a central plate attached to the movable mass. This fixed plate is driven by a square wave that is 180 degrees out of phase. When the beam is swung by acceleration, an unbalance is generated in the differential capacitor, and an output square wave having an amplitude proportional to the acceleration is generated. This signal is rectified using phase detection and demodulation techniques to determine the direction of acceleration.

  As shown in FIG. 7, the acceleration sensor 51 includes a sensor unit, a gain amplifier, a demodulator, a buffer amplifier, and a clock generation unit. The acceleration detected by the sensor unit is amplified to an appropriate magnitude by a gain amplifier, and the amplified signal is demodulated by a demodulator. Then, the demodulated signal is amplified again by the buffer amplifier and output.

  The output signal is processed by the vibration detection control unit of FIG. A signal output from the acceleration sensor 51 is sent to the CPU 402 via the filter 39. The filter 39 removes DC components and high frequency noise components from the input signal, and outputs them to the A / D converter 61 in the CPU 402. The A / D conversion unit 61 converts an analog signal from the sensor sent through the filter into digital data. The timing control unit 62 divides continuous digital data into data for each sheet by a predetermined timing signal. The output signal and timing signal of the acceleration sensor after passing through the filter 60 are shown in FIG. The timing signal is generated by a signal generation unit (not shown) using the sheet detection sensor 54 shown in FIG. 3 as a reference signal. As a result, the timing signal is kept at the on level while the conveyed sheet passes the conveying roller. Then, only the signal component during the period in which the timing signal is maintained at the on level is cut out from the input signal input to the CPU, and is provided to the feature amount calculation unit 42 as an output signal. In this way, the feature amount calculation unit 42 can obtain sensing data for each sheet. The feature amount calculation unit 42 calculates a feature amount useful for determining the vibration state of the conveying roller from the sensing data for each sheet given in this way. Based on the calculation result of the feature amount calculation unit 42, the CPU 402 outputs a control signal for controlling the current of the stepping motor 201 to the current setting circuit 411. The driving circuit 403 drives the stepping motor 201 based on the set current.

  Next, vibration detection of the transport roller will be described with reference to FIG.

  The acceleration sensor 51 detects vibration corresponding to the rotation operation of the transport rollers 42a and 42b.

  That is, when the conveyance sheet enters the conveyance rollers 42 a and 42 b, the vibration energy is applied to the acceleration sensor 51. By detecting the vibration energy, the vibration state of the transport rollers 42a and 42b is detected. The force applied to the acceleration sensor 51 has different vibration energy depending on the state of the transport rollers 42a and 42b. Causes include the type of sheet to be conveyed, gear rattling, load fluctuations such as wear of the conveying roller, and vibration of the motor itself. Further, the stepping motor sets the drive current by adding an appropriate amount of margin to the maximum load torque in order to prevent step-out due to load fluctuations. However, vibration and noise are generated due to excessive torque at low loads. Therefore, in this embodiment, as shown in FIG. 5, an acceleration sensor 51 is provided on the conveyance roller to detect the generated vibration, and when it can be determined that the torque is surplus, the drive current value is decreased to adjust the torque. To prevent vibration and noise. This also has the effect of saving power consumption by suppressing the supply of extra current. In the present embodiment, the control in the case where the vibration energy differs depending on the type of the sheet, which is one of the load fluctuation factors, will be described. In general, when the basis weight of a sheet is large, the thickness generally increases and the rigidity of the sheet increases. As a result, when thick paper having a large paper basis weight collides with the registration sensor, vibration energy larger than that of plain paper is detected. FIG. 9 is a diagram showing detection of vibration energy in plain paper and cardboard in this embodiment. This figure shows vibration energy applied to the acceleration sensor 51 when three sheets are conveyed continuously. As can be seen from this figure, when the conveyance sheet enters the conveyance roller, the vibration energy rises and the peak value is proportional to the basis weight of the paper. In this case, by setting the threshold level of the peak value to around 1.0, it becomes possible to detect plain paper and thick paper. Based on this result, the current of the stepping motor that drives the transport roller is controlled. In this embodiment, when the peak value of vibration energy is within the threshold value 1, the motor is driven with the motor setting current value being 0.7 A, and when the threshold value is 1 or more, The motor is driven at a motor set current value of 1.0A.

  Further, the switching timing of the motor drive setting current value may be performed between papers or between JOBs. When it is performed between sheets, it can be realized by outputting a switching signal from the CPU to the current setting circuit unit while the timing signal shown in FIG. 9 is at the off level. In addition, between JOBs, vibration level data at the time of the previous JOB is stored in the RAM, and when a new JOB comes, current setting is performed at the start of JOB operation based on the detection result of the previous JOB data. It can be realized by switching.

  Next, the control sequence in the present embodiment will be described with reference to the flowchart of FIG.

  Here, a description will be given of the current switching control between sheets during the printing operation for two consecutive sheets.

  First, in step S1001, the presence or absence of JOB is determined. If it is determined that JOB is present, the first sheet feeding operation is executed in step S1002. In step S1003, the sheet sensor checks whether the first sheet is conveyed at a predetermined timing. If the sheet sensor is turned on at a predetermined timing, the driving of the conveying roller is started in step S1004 at a predetermined timing after the sheet sensor is turned on. In step S1005, the vibration of the conveying roller in the first sheet operation is detected. In step S1006, vibration detection data is stored in the memory. In step S1007, the first image forming operation is executed, and in step S1008, the second sheet feeding operation is started. In step S1009, it is determined whether the first vibration level is within a predetermined threshold. If it is determined that it is within the predetermined threshold value, the drive motor current setting is switched in step S1010. In step S1011, it is confirmed by the sheet sensor whether the second sheet is conveyed at a predetermined timing. If the sheet sensor is turned on at a predetermined timing, the driving of the conveying roller is started at a predetermined timing from the sheet sensor ON in step S1012. In step S1013, vibration of the transport roller in the second operation is detected. In step S1014, the second vibration detection data is stored in the memory. In step S1015, the second image forming operation is executed, and in step S1016, the job ends. If the sheet sensor is not turned ON at a predetermined timing in step S1003, it is determined as JAM (paper clogging) and the conveyance roller is stopped. If it is determined in step S1018 that the JAM (paper clogging) process is finished, the first sheet feeding operation is executed again in step S1002. If the sheet sensor is not turned ON at a predetermined timing in step S1011, it is determined that the paper is jammed (JAM), and the conveyance roller is stopped. If it is determined in step S1020 that the JAM (paper clogging) process has ended, the second sheet feeding operation is executed again in step S1008. If the vibration level is greater than or equal to the threshold value in step S1009, the control operation is continued without switching the current.

  Further, in the present embodiment, it is reflected at the time of the next sheet conveyance based on the vibration data for one sheet. However, data for a plurality of sheets is processed instead of one sheet, and is reflected in the next JOB. There is no problem. Further, in this embodiment, the current switching is performed in two stages, but it goes without saying that a plurality of stages of current switching can also be applied according to the vibration level. Further, in the present embodiment, the description has been made with respect to one certain conveying roller, but it goes without saying that the present invention can also be applied to other conveying rollers. In this embodiment, the detection is performed by attaching the acceleration sensor to the conveyance roller. However, it goes without saying that there is no problem even if it is attached to the shaft itself connected to the conveyance roller. In the present embodiment, the output device that mainly performs the image forming operation has been described. However, it goes without saying that the present invention can also be applied to a document conveying device that performs image reading.

  As described above, it is possible to prevent vibration and noise by providing an acceleration sensor on the transport roller, detecting the generated vibration, and controlling the drive current value based on the detection result. This also has the effect of saving power consumption by suppressing the supply of extra current.

[Second Embodiment]
Next, a second embodiment will be described. In the first embodiment, the motor drive current is controlled based on the vibration detection result, but in the second embodiment, the motor excitation method is controlled.

  For example, when vibration data as shown in FIG. 9 is obtained, the control is switched to 1-2 phase excitation if the threshold is within 1, and the two phase excitation method is used if the threshold is 1 or more. Control.

  Here, the excitation timings of the two-phase excitation method and the 1-2 phase excitation method are shown in FIG. The two-phase excitation method is a method in which two phases are excited simultaneously as shown in FIG. Although power consumption increases, a larger torque can be obtained. Therefore, when the vibration level of the conveying roller is large and the load fluctuation is large, the control is performed by two-phase excitation. Next, the 1-2 phase excitation method is an excitation method in which one-phase excitation and two-phase excitation are alternately repeated as shown in FIG. The power consumption is about 0.7 times that of two-phase excitation, and the motor torque is smaller than that of two-phase excitation. Therefore, when the vibration level of the conveying roller is small and the load fluctuation is small, the control is performed by 1-2 phase excitation.

  Further, the switching timing of the motor excitation method may be performed between papers or between JOBs. When it is performed between sheets, it can be realized by outputting an excitation signal from the rotation speed variable control unit 412 while the timing signal shown in FIG. In addition, the vibration level data at the time of the previous JOB is stored in the RAM between JOBs, and when a new JOB comes, an excitation signal is generated at the start of JOB operation based on the detection result of the previous JOB data. It can be realized by switching.

  By performing such control, when it can be determined that the torque is excessive, the excitation method is switched and the torque is adjusted to prevent vibration and noise. This also has the effect of saving power consumption by suppressing the supply of extra current.

  Next, a control sequence in the second embodiment will be described with reference to the flowchart of FIG. Here, a description will be given of the excitation method control between sheets during the printing operation of two continuous sheets.

  First, in step S1201, the presence or absence of JOB is determined. If it is determined that JOB is present, the first sheet feeding operation is executed in step S1202. In step S1203, the sheet sensor checks whether the first sheet is conveyed at a predetermined timing. If the sheet sensor is turned on at a predetermined timing, the driving of the conveying roller is started in step S1204 at a predetermined timing after the sheet sensor is turned on. In step S1205, the vibration of the conveying roller in the first sheet operation is detected. In step S1206, vibration detection data is stored in the memory. In step S1207, the first image forming operation is executed, and in step S1208, the second sheet feeding operation is started. In step S1209, it is determined whether the first vibration level is within a predetermined threshold. If it is determined that the value is within the predetermined threshold value, the excitation method of the drive motor is switched in step S1210. In step S1211, it is confirmed by the sheet sensor whether the second sheet is conveyed at a predetermined timing. If the sheet sensor is turned on at a predetermined timing, the driving of the conveying roller is started at a predetermined timing from the sheet sensor ON in step S1212. In step S1213, the vibration of the conveying roller in the second operation is detected. In step S1214, the second vibration detection data is stored in the memory. In step S1215, the second image forming operation is executed, and in step S1216, the job ends. If the sheet sensor is not turned on at a predetermined timing in step S1203, it is determined as JAM (paper clogging) and the conveyance roller is stopped. If it is determined in step S1218 that the JAM (paper clogging) process is finished, the first sheet feeding operation is executed again in step S1202. If the sheet sensor is not turned on at a predetermined timing in step S1211, it is determined that the sheet sensor is JAM (paper clogging), and the conveyance roller is stopped. If it is determined in step S1220 that the JAM (paper clogging) process has ended, the second sheet feeding operation is executed again in step S1208. If the vibration level is equal to or higher than the threshold value in step S1209, the control operation is continued without switching the excitation method.

  Further, in the present embodiment, it is reflected at the time of the next sheet conveyance based on the vibration data for one sheet. However, data for a plurality of sheets is processed instead of one sheet, and is reflected in the next JOB. There is no problem. Further, in this embodiment, the excitation method switching is performed in two stages. Needless to say, however, a plurality of stages of excitation system switching such as a combination of microstep control can be applied according to the vibration level. Further, in the present embodiment, the description has been made with respect to one certain conveying roller, but it goes without saying that the present invention can also be applied to other conveying rollers. In this embodiment, the detection is performed by attaching the acceleration sensor to the conveyance roller. However, it goes without saying that there is no problem even if it is attached to the shaft itself connected to the conveyance roller. In the present embodiment, the output device that mainly performs the image forming operation has been described. However, it goes without saying that the present invention can also be applied to a document conveying device that performs image reading. In this embodiment, a capacitance type acceleration sensor is used as the vibration detection means. However, there is no problem with a piezoelectric type vibration sensor, acceleration sensor, displacement sensor, or strain sensor.

  As described above, it is possible to prevent vibration and noise by providing an acceleration sensor on the transport roller, detecting the generated vibration, and controlling the motor excitation method based on the detection result. This also has the effect of saving power consumption by suppressing the supply of extra current.

Internal configuration diagram of an image forming apparatus to which a sheet conveying device is applied Block diagram for performing motor control and vibration detection control in this embodiment Detailed block diagram of variable speed controller Detailed structure of the sheet transport system The figure which shows the structure of the sheet conveyance path which detects the vibration of a conveyance roller. A diagram detailing the arrangement of acceleration sensors that detect the vibration of the transport rollers Diagram showing internal block configuration of acceleration sensor Diagram showing the principle of operation of the acceleration sensor Diagram showing detection of vibration energy in plain paper and cardboard Flow chart showing a control sequence in the present embodiment The figure which showed the excitation timing of the motor excitation system in 2nd Example The flowchart which showed the control sequence in 2nd Example.

Explanation of symbols

31 Photosensitive drum 42 Conveying roller 51 Acceleration sensor 54 Sheet sensor 411 Current setting circuit 412 Rotation speed variable control unit

Claims (7)

A sheet material conveying member for conveying the sheet material;
Conveying member driving means for driving the sheet material conveying member;
Comprising vibration detecting means for detecting vibration of the sheet material conveying member;
An image forming apparatus, wherein a driving current of the conveying member driving unit is changed based on a vibration of the vibration detecting unit. A sheet material conveying member for conveying the sheet material;
Conveying member driving means for driving the sheet material conveying member;
Comprising vibration detecting means for detecting vibration of the sheet material conveying member;
An image forming apparatus, wherein an excitation method of the conveying member driving unit is changed based on vibration of the vibration detecting unit.   The image forming apparatus according to claim 1, wherein the sheet material conveying member is a conveying roller.   The image forming apparatus according to claim 1, wherein the conveying member driving unit is a stepping motor.   The image forming apparatus according to claim 1, wherein the timing for controlling the driving current of the conveying member driving unit is between sheets.   The image forming apparatus according to claim 1, wherein the timing for controlling the driving current of the conveying member driving unit is between JOBs.   The image forming apparatus according to claim 1, wherein the vibration detection unit is an acceleration sensor.