JP2006160512A - Endless moving member drive control device, image formation device, and method of controlling moving speed of endless moving member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately control the moving speed of an endless moving member without being affected by the mounting error of sensors and the pitch error and extension/retraction of marks. <P>SOLUTION: A large number of marks formed continuously on the surface of an intermediate transfer belt 10 as the endless moving member at equal intervals are detected by a mark sensor 6, the detected signals are counted by a mark counter 12, and their integrated value is taken as moved position information on the intermediate transfer belt 10. On the other hand, pulse signals outputted from a rotary encoder 19 mounted on the rotating shaft of the intermediate transfer belt 10 are converted into rotating speed signals by an f-V conversion circuit 37. Then, based on the rotating speed signals and the moved position information, a controlling controller 71 controls the drive force of a motor 7 while correcting target position data and controls the moving speed of the intermediate transfer belt 10 by feedback. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a belt-shaped or drum-shaped endless moving member, in particular, various endless moving member drive control devices used in an image forming apparatus such as a copying machine or a printer, an image forming apparatus including the same, and an endless moving member thereof The present invention relates to a moving speed control method.

In recent years, for example, copiers and printers, which are image forming apparatuses using an electrophotographic system, are increasingly capable of forming full-color images in accordance with market demands.
A color image forming apparatus capable of forming such a color image is provided with a plurality of developing devices that perform development with toner of each color around one photosensitive member, and a latent image on the photosensitive member is formed by these developing devices. There is a so-called one-drum type in which a toner is attached to form a full-color synthetic toner image, and the toner image is sequentially superimposed and transferred onto a recording material sheet or a transfer belt to obtain a color image.

  Further, the image forming units for the respective colors including the photoconductor and the developing device are arranged in a straight line, and the toner images of the respective colors formed by the respective image forming units are carried on the sheet conveying belt and conveyed. A direct transfer system that forms a full-color image directly on the sheet (paper) by transferring the image on the sheet (paper), and a toner image of each color formed by the image forming unit for each color on the intermediate transfer belt. There is also an indirect transfer type tandem type color image forming apparatus in which a full-color image is formed by sequentially superimposing and transferring, and the color image is collectively transferred onto a sheet (paper) by a secondary transfer device.

  In any of these color image forming apparatuses, toner images of a plurality of colors (for example, four colors of yellow, cyan, magenta, and black) are created, and the toner images are formed on a sheet or a transfer belt (also referred to as an intermediate transfer belt). Since the color image is formed by sequentially superimposing and transferring the image on the upper side, if the overlapping positions of the toner images of the respective colors are deviated, the color deviation and the hue are changed, and the image quality is deteriorated. Accordingly, it has been an important problem to prevent a shift (color shift) in the transfer position of each color toner image.

It is known that the main cause of the color misregistration is uneven movement speed of the photosensitive drum (or photosensitive belt), the sheet conveying belt, the transfer belt (intermediate transfer belt), and the like.
Therefore, for example, as seen in Patent Document 1, in a one-drum type color image forming apparatus, the amount of movement of a rotating body such as a transfer belt can be accurately detected, and this is used for controlling the moving speed of the rotating body. Thus, it has been proposed to prevent deterioration in image quality such as color misregistration.

In Patent Document 1, toner images of four colors of cyan, magenta, yellow, and black are sequentially formed on the outer peripheral surface of a photosensitive drum for each rotation, and are sequentially superimposed on the surface of an endless transfer belt. A one-drum type color copying machine is described which forms a full-color image by transferring.
The transfer belt is then provided with a scale consisting of marks (scales) that are continuous in the direction of movement in the direction of movement, and the scale is read with an optical detector to detect the amount of movement of the transfer belt directly and accurately. Then, the detected moving amount is fed back by a feedback control system to accurately control the moving speed of the transfer belt. Furthermore, a scale is also provided on the surface of the photosensitive drum or other rotating body so that the same movement amount can be detected and the movement speed can be controlled.

According to this method, since the amount of movement of the surface of the rotating body such as the transfer belt is directly detected, the actual amount of movement of the surface of the rotating body should be able to be detected with high accuracy. However, in reality, there is a random variation in the interval (pitch) between the marks on the scale, so that the detected movement amount includes this and is not necessarily highly accurate.
Thus, for example, Patent Document 2 proposes a belt conveyance device that improves this point.
JP 11-24507 A Japanese Patent No. 3344614

  The belt conveyance device described in Patent Document 2 repeatedly provides a plurality of marks at a predetermined pitch in the conveyance direction on a carrier made of an endless belt such as an intermediate transfer belt that carries paper or a toner image, Two photoelectric sensors for sequentially reading the marks are provided with their positions shifted in the carrying direction of the carrier, and when the carrier is driven by the driving means, based on the outputs of the two sensors, The time difference at which the two sensors detect the same mark is calculated. Further, an average value is obtained for a plurality of time difference calculation results, and the control means controls the driving speed of the carrier by the driving means based on the calculation result of the average value and the time difference calculation result.

  In this case, the average value of the time difference during which the same mark passes through the two sensors is obtained over the integral rotation of the drive roll that drives the carrier, and this is used as the average speed of the carrier. This average speed is substantially equal to the rotational speed of the drive source, and is based on the recognition that the rotational speed of the drive source is suppressed to a fluctuation of a few percent of commas. Therefore, this average value is a highly accurate reference, and if the rotational speed of the drive source is controlled based on this reference, the speed of the carrier such as the intermediate transfer belt can be controlled to a stable and constant speed.

  However, it is difficult to form the scales and marks on the belt-like or drum-like endless moving members with high accuracy, and the temperature and humidity of the environment, and in the case of a belt, it expands and contracts due to roller tension. (Pitch) changes. Further, since the interval between the two sensors is also affected by an attachment error or expansion / contraction of the attachment member due to temperature, it is difficult to manage at an absolute position.

  For this reason, the method described in Patent Document 1 is directly affected by variations in the interval (pitch) of the scale marks as described above, so that it is difficult to control the transfer belt or the like with high accuracy. Also in the method described in Patent Document 2, the time difference during which the same mark passes through the two sensors is not only influenced by the fluctuation of the mark pitch and the interval between the two sensors, but also by the moving speed of the transfer belt or the like. Also changes. Therefore, even if the average value is taken, it cannot be said that it is an accurate reference value, and it is difficult to control the speed or position with high accuracy even if the drive speed of the transfer belt or the like is controlled based on the average value. It was not possible to eliminate color misregistration and density unevenness and to always obtain a high-quality image.

  The present invention has been made to solve such problems, and is a drive control device or a moving speed of various belt-like or drum-like endless moving members including a transfer belt and a photosensitive drum in an image forming apparatus. An object of the control method is to enable the moving speed of the endless moving member to be controlled with high accuracy, and thereby to always guarantee high-quality image formation (not limited to a full-color image) by the image forming apparatus. And

  An endless moving member drive control device according to the present invention is an endless moving member drive control device comprising a belt-shaped or drum-shaped endless moving member and a driving means for rotating the endless moving member. In order to achieve the above, on the surface or back surface of the endless moving member, a plurality of marks are provided so as to continue at a predetermined interval over the moving direction, and a mark sensor that detects the mark as the endless moving member moves, A rotary encoder that outputs a pulse signal corresponding to the rotation angle of the shaft member that rotates in conjunction with the rotation of the endless moving member, and a signal conversion means that converts the pulse signal output from the rotary encoder into a rotation speed signal; And a counter that counts a mark detection signal output from the mark sensor and outputs movement position information of the endless moving member. Furthermore, control means for feedback-controlling the moving speed of the endless moving member by the driving means based on the rotational speed signal output from the signal converting means and the moving position information output from the counter is provided. .

  The control means is a speed command generating means for generating a speed command according to a difference between a preset target position and the moving position information, and according to a difference between the generated speed command and the rotational speed signal. Torque command generating means for generating a torque command may be provided, and the driving force of the driving means may be controlled by the torque command generated by the torque command generating means.

  Alternatively, a plurality of mark sensors for detecting the marks are provided at predetermined intervals along the moving direction of the endless moving member, and the phase difference between the mark detection signals output from the plurality of mark sensors is calculated as described above. Phase difference calculating means for sequentially calculating with the movement of the endless moving member, a rotary encoder for outputting a pulse signal corresponding to the rotation angle of the shaft member rotating in conjunction with the rotation of the endless moving member, and the rotary encoder And a signal conversion means for converting the pulse signal output from the rotation speed signal into a rotation speed signal, and further, the driving based on the rotation speed signal output from the signal conversion means and the phase difference calculated by the phase difference calculation means. Control means for performing feedback control of the moving speed of the endless moving member by the means may be provided.

  In this case, the control means includes a target position correcting means for correcting a preset target position by a phase difference calculated by the phase difference calculating means, and a speed corresponding to the target position corrected by the target position correcting means. A speed command generating means for generating a command, and a torque command generating means for generating a torque command in accordance with a difference between the speed command generated by the means and the rotational speed signal. The driving force of the driving means may be controlled by a torque command.

Further, a counter that counts a mark detection signal output from any of the plurality of mark sensors and outputs movement position information of the endless moving member may be provided.
In this case, the control means includes a target position correcting means for correcting a preset target position by a phase difference calculated by the phase difference calculating means, a target position corrected by the target position correcting means, and the moving position. Speed command generating means for generating a speed command according to the difference with the information, and torque command generating means for generating a torque command according to the difference between the speed command generated by the means and the rotational speed signal, The driving force of the driving means may be controlled by the torque command generated by the torque command generating means.

The phase difference calculating means measures the time difference between rising edges or falling edges of the mark detection signals output from the plurality of mark sensors by using the pulse signal output from the rotary encoder as a reference clock. More preferably, it is a means for calculating the phase difference.
The plurality of mark sensors may be integrally supported by the same support member.
The interval between the plurality of mark sensors is preferably shorter than the moving distance of the endless moving member by one rotation of the motor of the driving means.

Furthermore, it is preferable to provide mark defect / seam detection means for detecting a defect or a joint of a plurality of marks continuous at the predetermined interval based on the phase difference calculated by the phase difference calculation means.
When the mark defect / seam detection means detects that a mark defect or seam is located between the plurality of mark sensors, the control means stops feedback control of the moving speed of the endless moving member. You may make it do.

  An image forming apparatus according to the present invention includes the endless moving member drive control device, and the endless moving member is at least one of a transfer belt, an intermediate transfer belt, a photosensitive belt, a paper transport belt, an intermediate transfer drum, and a photosensitive drum. One.

A moving speed control method according to the present invention is a moving speed control method when a belt-shaped or drum-shaped endless moving member is rotated by a driving means, and in order to achieve the above-mentioned object, the surface of the endless moving member or A plurality of marks are provided on the back surface so as to be continuous at a predetermined interval in the moving direction, the plurality of marks are detected by a mark sensor as the endless moving member moves, and the endless movement is detected from the mark detection signal. The movement position information of the member is acquired.
On the other hand, a pulse signal corresponding to the rotation angle of the shaft member is output by a rotary encoder attached to the shaft member rotating in conjunction with the rotation of the endless moving member, and the pulse signal is converted into a rotation speed signal.
Then, the moving speed of the endless moving member by the driving means is feedback controlled by the rotation speed signal and the moving position information.

In the moving speed control method for the endless moving member, the pulse signal output from the rotary encoder is counted between the rising or falling edges of the mark detection signal output from the mark sensor, and the count value is integrated. You may make it acquire the movement position information of the said endless moving member.
Then, a speed command is generated according to a difference between a preset target position and the movement position information, a torque command is generated according to a difference between the speed command and the rotation speed signal, and the torque command The driving force of the driving means can be controlled.

Further, the plurality of marks are detected by a plurality of mark sensors arranged at predetermined intervals along the moving direction of the endless moving member, and from the plurality of mark sensors as the endless moving member moves. The phase difference between the output mark detection signals may be calculated sequentially, and the moving speed of the endless moving member by the driving means may be feedback controlled based on the phase difference and the rotation speed signal.
In this endless moving member movement control method, a time difference between rising edges or falling edges of mark detection signals output from the plurality of mark sensors is measured using a pulse signal output from the rotary encoder as a reference clock. The phase difference may be calculated by

  Further, the mark detection signal output from any one of the plurality of mark sensors is counted to obtain the movement position information of the endless moving member, and the preset target position is corrected by the phase difference calculated sequentially. Then, a speed command is generated according to the difference between the corrected target position and the moving position information, a torque command is generated according to the difference between the speed command and the rotation speed signal, and the driving is performed according to the torque command. The driving force of the means can be controlled.

  According to the endless moving member drive control device and the endless moving member moving speed control method according to the present invention, the feedback control by detecting the rotational speed by the rotary encoder, the position information of the endless moving member itself by the mark detection signal of the mark sensor, or Since the feedback control based on the positional deviation information based on the phase difference is combined, it is possible to perform sufficiently high speed control.

In particular, if a plurality of mark sensors are provided, the phase difference between the mark detection signals is calculated, and the target position set in advance is corrected based on the phase difference, the mark pitch error and the expansion / contraction of the belt, etc. It is possible to control the speed more accurately with less influence.
When the phase difference between the rising edges or falling edges of the mark detection signals output from a plurality of mark sensors is calculated by measuring the pulse signal output from the rotary encoder as a reference clock, the rotational speed of the endless moving member Even if fluctuates, a phase difference corresponding to the amount of movement can always be obtained with the same accuracy.

In addition, if a plurality of mark sensors are integrally supported by the same support member, preferably a member made of a material having a low coefficient of linear expansion, the absolute position of the sensor interval is managed, and the phase difference due to expansion and contraction of the endless moving member is reduced. It can also be calculated more accurately.
It is also possible to prevent the movement speed feedback control from being disturbed by a defective mark or a joint.

  According to the image forming apparatus of the present invention, it is possible to accurately control the moving speed of an endless moving member related to image formation such as a transfer belt, an intermediate transfer belt or a drum, a photosensitive drum or a belt, a paper conveying belt, etc. It is always possible to guarantee high-quality image formation without distortion.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIGS. 1 and 2 are block diagrams showing configurations of first and second embodiments of an endless moving member drive control device and an endless moving member speed control method according to the present invention, respectively. FIG. 3 schematically shows the internal structure of an example of a color image forming apparatus that includes the endless moving member drive control device according to the present invention and that performs the speed control method of the endless moving member.
First, the image forming apparatus will be described.

In this color image forming apparatus, an apparatus main body 1 is placed on a sheet feed table 2 as shown in FIG. A scanner 3 is mounted on the apparatus body 1 and an automatic document feeder (ADF) 4 is mounted thereon.
In the apparatus main body 1, a transfer device 20 having an intermediate transfer belt 10 that is a belt-like endless moving member is provided at substantially the center thereof. The intermediate transfer belt 10 includes a driving roller 9 and two driven rollers 15 and 16. It is stretched between and rotated in the clockwise direction in FIG.

  The intermediate transfer belt 10 is configured so that residual toner remaining on the surface after image transfer is removed by a cleaning device 17 provided on the left side of the driven roller 15. Above the linear portion spanned between the driving roller 9 and the driven roller 15 of the intermediate transfer belt 10, yellow (Y), cyan (C), magenta along the moving direction of the intermediate transfer belt 10. Four drum-shaped photoconductors 40Y, 40C, 40M, and 40K (hereinafter simply referred to as photoconductors 40 if not specified) of (M) and black (K) are arranged at predetermined intervals. . Then, four primary transfer rollers 62 are provided inside the intermediate transfer belt 10 so as to oppose the respective photoreceptors 40 and sandwich the intermediate transfer belt 10 therebetween.

Each of the four photoconductors 40 can be rotated in the counterclockwise direction in FIG. 3. Around the photoconductors 40, a charging device 60, a developing device 61, the above-described primary transfer roller 62, and the like, respectively. A photoconductor cleaning device 63 and a charge removal device 64 are provided, and each constitutes an image forming unit 18. A common exposure device 21 is provided above the four image forming units 18.
Each image (toner image) formed on each photoconductor is successively transferred onto the intermediate transfer belt 10 in a superimposed manner.

  On the other hand, on the lower side of the intermediate transfer belt 10, a secondary transfer device 22 serving as a transfer unit that transfers an image on the intermediate transfer belt 10 to a sheet P that is a recording sheet is provided. The secondary transfer device 22 is a belt in which a secondary transfer belt 24 that is an endless belt is stretched between two rollers 23 and 23, and the secondary transfer belt 24 is driven by a driven roller 16 via an intermediate transfer belt 10. It comes to be pressed against.

The secondary transfer device 22 collectively transfers the toner images on the intermediate transfer belt 10 onto a sheet P fed between the secondary transfer belt 24 and the intermediate transfer belt 10.
A fixing device 25 for fixing the toner image on the sheet P is provided downstream of the secondary transfer device 22 in the sheet conveying direction. A pressure roller 27 is pressed against the fixing belt 26 which is an endless belt. Yes.

The secondary transfer device 22 also functions to convey the sheet after image transfer to the fixing device 25. Further, the secondary transfer device 22 may be a transfer device using a transfer roller or a non-contact charger. A sheet reversing device 28 is provided below the secondary transfer device 22 for reversing the sheet when images are formed on both sides of the sheet.
As described above, the apparatus main body 1 constitutes an indirect transfer tandem color image forming apparatus.

  When making a color copy with this color image forming apparatus, the document is set on the document table 30 of the automatic document feeder 4. When the document is manually set, the automatic document feeder 4 is opened, the document is set on the contact glass 32 of the scanner 3, and the automatic document feeder 4 is closed and pressed.

  When a start key (not shown) is pressed, when the document is set on the automatic document feeder 4, the document is fed onto the contact glass 32. When the document is manually set on the contact glass 32, the scanner 3 is immediately driven, and the first traveling body 33 and the second traveling body 34 start traveling. Then, light is emitted from the light source of the first traveling body 33 toward the document, and reflected light from the document surface is directed to the second traveling body 34, and the light is reflected by the mirror of the second traveling body 34. The light enters the reading sensor 36 through the imaging lens 35 and the content of the original is read.

  Further, when the start key is pressed, the intermediate transfer belt 10 starts to rotate. At the same time, the photoconductors 40Y, 40C, 40M, and 40K start to rotate, and yellow (Y), cyan (C), magenta (M), and black (K) monochromatic toners on the photoconductors. The operation for forming an image is started. The toner images of the respective colors formed on the respective photoconductors are sequentially transferred while being superimposed on the intermediate transfer belt 10 that rotates in the clockwise direction in FIG. 2, and a full-color composite color image is formed there. It is formed.

  On the other hand, when the start key described above is pressed, the paper feed roller 42 of the selected paper feed stage in the paper feed table 2 rotates, and the sheet P is fed from one selected paper feed cassette 44 in the paper bank 43. The paper is fed out, separated into one sheet by the separation roller 45, and conveyed to the paper feed path 46. The sheet P is transported to the paper feed path 48 in the apparatus main body 1 by the transport roller 47, hits the registration roller 49, and temporarily stops.

In the case of manual sheet feeding, the sheet P set on the manual tray 51 is fed out by the rotation of the sheet feeding roller 50, and is separated into one sheet by the separation roller 52 and conveyed to the manual sheet feeding path 53. Then, it hits the registration roller 49 and temporarily stops.
The registration roller 49 starts to rotate at an accurate timing in accordance with the composite color image on the intermediate transfer belt 10, and temporarily stops the sheet P between the intermediate transfer belt 10 and the secondary transfer device 22. Send it in. Then, a color image is transferred onto the sheet P by the secondary transfer device 22.

The sheet P on which the color image has been transferred is conveyed to a fixing device 25 by a secondary transfer device 22 that also functions as a conveying device, where the transferred color image is fixed by applying heat and pressure. . Thereafter, the sheet P is guided to the discharge side by the switching claw 55, is discharged onto the discharge tray 57 by the discharge roller 56, and is stacked there.
When the double-sided copy mode is selected, the sheet P on which an image is formed on one side is conveyed to the sheet reversing device 28 side by the switching claw 55, reversed there and led again to the transfer position, and this time the image is printed on the back side. After the formation, the paper is discharged onto a paper discharge tray 57 by a discharge roller 56.

A portion of the image forming apparatus corresponding to the endless moving member drive control apparatus according to the present invention will be described with reference to FIGS. FIG. 4 is a perspective view showing a schematic configuration of the first embodiment and FIG. 6 is a schematic configuration of the second embodiment.
The intermediate transfer belt 10 that is an endless moving member is stretched between the driving roller 9 and the driven roller 15, and is tensioned by the driven roller 16. Then, when the driving roller 9 is rotated by the motor 7 via the speed reducer 8, the motor 7 rotates in the direction indicated by the arrow F.
The intermediate transfer belt 10 is a belt formed of, for example, a fluorine-based resin, a polycarbonate resin, a polyimide resin, or the like, and an elastic belt in which all layers or a part of the belt is formed of an elastic member is often used. .

  A plurality of marks 5 are provided along one side edge of the outer peripheral surface of the intermediate transfer belt 10 so as to be continuous at a predetermined interval (pitch) in the moving direction. In this example, a large number of marks 5 are provided over the entire circumference of the intermediate transfer belt 10 so that the scale 250 is formed with extremely small bits (equal intervals). In the figure, the mark 5 is shown in a black scale, but in actuality, the mark 5 is printed with ink having a higher reflectance than the surface of the intermediate transfer belt 10, or the mark 5 having a reflectance different from the reflectance of the ground is printed. A tape is attached to the entire circumference of the intermediate transfer belt 10.

In the first embodiment shown in FIG. 4, one mark sensor 6 is provided above the side edge of the intermediate transfer belt 10 where the mark 5 is provided. In the second embodiment shown in FIG. A plurality (two in this example) of mark sensors 6A and 6B are arranged at predetermined intervals along the moving direction of the transfer belt 10 (direction indicated by arrow F).
An example of the arrangement relationship between the mark 5 and the two mark sensors 6A and 6B is shown in an enlarged manner in FIG.
Assuming that the design value of the interval (pitch) of the marks 5 forming the scale 250 is P0, the interval D of the detection points of the mark sensors 6A and 6B is an integral multiple of the pitch P0 of the marks 5, that is, D = N · P0 ( N is preferably 1, 2, 3,. In this embodiment, the mark sensor 6A is disposed downstream of the moving direction of the intermediate transfer belt 10 (direction indicated by arrow F), and the mark sensor 6B is disposed upstream.

The first embodiment shown in FIG. 4 is the same as that in which only one of the two mark sensors 6A and 6B shown in FIG. 7 is provided.
In the first embodiment, a mark detection signal from one mark sensor 6 is input to the control device 70. In the second embodiment shown in FIG. 6, the mark detection signals from the two mark sensors 6A and 6B are input to the control device 70, respectively.
Note that the scale 250 by the mark 5 may be provided on the inner peripheral surface of the intermediate transfer belt 10. In that case, of course, the mark sensor 6 or 6A, 6B is also disposed inside the intermediate transfer belt 10.

  In any of the embodiments, the control device 70 drives the motor 7, and the motor 7 rotates the drive roller 9 via the speed reducer 8, thereby rotating the intermediate transfer belt 10 in the direction indicated by the arrow F. Let As the intermediate transfer belt 10 moves, one mark sensor 6 or two mark sensors 6A and 6B detect the mark 5 of the scale 250 and input the signal to the controller 70. A rotary encoder 19 that outputs a pulse signal corresponding to the rotation angle is attached to the rotation shaft of the motor 7. The pulse signal from the rotary encoder 19 is also input to the control device 70.

Since the rotary encoder 19 may be attached to a shaft member that rotates in conjunction with the rotation of the intermediate transfer belt 10, the rotary encoder 19 may be attached to either the drive roller 9 or the driven rollers 15 and 16.
The control device 70 inputs the mark detection signal from these mark sensors 6 or 6A, 6B and the pulse signal corresponding to the rotation angle of the rotating shaft of the motor 7 from the rotary encoder 19 to drive the motor 7. A signal (voltage) is controlled, and the moving speed of the intermediate transfer belt 10 is feedback-controlled. Details thereof will be described later.

FIG. 5 shows a detection signal of the mark 5 on the intermediate transfer belt 10 by the mark sensor 6 shown in FIG. 4 (referred to as “mark sensor signal” in the figure) and a waveform of a reference clock for measuring the cycle thereof. ing. The reference clock is assumed to have a frequency of fc and a period of tc. The frequency is fc, fc> {belt conveyance speed} / {target measurement system}
And In this embodiment, the belt is the intermediate transfer belt 10.
When the belt conveyance speed is V and the pitch of the mark 5 is P, the mark interval T (n) is
T (n) = P / V (n).
Since tc = 1 / fc, if the resolution at this time is d,
d = P / (T (n) / tc) = V / fc
It becomes. In addition to the pitch of the marks 5, the frequency of the reference clock that divides the marks is also a factor that determines the measurement accuracy.

  FIG. 8 is a configuration diagram showing an example of a scale 250 and a mark sensor 6 (6A and 6B are the same since 6A and 6B are the same) provided on the outer peripheral surface of the intermediate transfer belt. a) is a plan view of a part of the scale 250 as viewed from above, and (b) is a side perspective view showing the configuration and optical path of the optical system of the mark sensor 6, which are shown upside down for convenience. (C) is a plan view of the detection surface of the mark sensor 6.

The scale 250 is a reflective scale, and is formed by alternately forming marks (reflecting portions) 5 and light shielding portions 58 along the rotation direction on the outer peripheral surface (or inner peripheral surface) of the intermediate transfer belt 10. is there.
The mark sensor 6 includes a light emitting element 111 such as an LED, a collimating lens 112, a light receiving window 114 provided with a slit mask 113 and a transparent cover such as glass or a transparent resin film as clearly shown in FIG. A light receiving element 115 such as a transistor is fixed to the housing 110.

  In the mark sensor 6, the light emitted from the light emitting element 111, which is a light source, passes through the collimator lens 112 to become a parallel light flux, and passes through a slit mask 113 in which a plurality of slits 113 a arranged in parallel with the scale 250 is formed. The light beam LB is divided into a plurality of light beams LB and irradiated on the scale 250 on the intermediate transfer belt. A part of the reflected light is reflected by the mark 5, and the reflected light is received by the light receiving element 115 through the light receiving window 114. The light receiving element 115 converts the change in brightness of the reflected light into an electric signal.

Therefore, the light receiving element 115 of the housing 110 of the mark sensor detects the mark 5 of the scale 250 by receiving the reflected light, and is continuously analog-modulated by the presence or absence of the reflecting portion 251 due to the rotation of the intermediate transfer belt. Output a signal. When the signal is waveform-shaped, a rectangular pulse signal as shown in FIG. 9 is obtained.
FIG. 9 is a diagram (timing chart) showing the relationship between the waveform obtained by shaping the output signals of the two mark sensors 6A and 6B and the phase difference thereof.

In this figure, (a) shows the waveform of the detection signal from the mark sensor 6A, Ca (1), Ca (2), Ca (n) are their respective periods, and (b) is the detection signal from the mark sensor 6B. Where Cb (1), Cb (2), and Cb (n) indicate their respective periods. (C) shows the waveform of the phase difference between the detection signals of the mark sensors 6A and 6B, and Cab (1), Cab (2), and Cab (n) are the phase differences.
Here, an area composed of the slit mask 113 and the light receiving window 114 on the detection surface of the mark sensor 6 shown in FIG. 8C is a mark detection area SA, and the mark detection areas SA of the two mark sensors 6A and 6B. The positional relationship with the mark 5 detected thereby will be described with reference to FIG.

As shown in FIG. 7, if the pitch P0 of the mark 5 remains the design value (initial value) and the distance D between the two mark sensors 6A and 6B is exactly N · P0, When the center line CLa of the mark detection area SA of the mark sensor 6A shown on the right side coincides with the center of the width of the mark 5 being detected, the mark 5 corresponding to the mark detection area SA of the mark sensor 6B shown on the left side is also shown by a broken line. The center of the width coincides with the center line CLb of the mark detection area SA.
Therefore, the rising and falling timings of the waveforms obtained by shaping the output signals of the mark sensors 6A and 6B coincide with each other, and the phase difference Cab = 0.

In practice, however, the intermediate transfer belt 10 expands and contracts due to the temperature and humidity in the machine and the tension applied to the intermediate transfer belt 10, thereby shifting the position of the mark 5 on the scale 250.
Therefore, when the center line CLa of the mark detection area SA of the mark sensor 6A shown on the right side of FIG. 10 coincides with the center of the width of the mark 5 being detected, the mark corresponding to the mark detection area SA of the mark sensor 6B shown on the left side 5 shifts as indicated by a solid line, and the center of its width deviates from the center line CLb of the mark detection area SA (when the pitch of the mark 5 increases, the movement direction of the intermediate transfer belt 10 indicated by an arrow F). It will be late.) As a result, as shown in FIG. 9, the rising and falling timings of the waveforms obtained by shaping the output signals of the mark sensors 6A and 6B are shifted, and a phase difference Cab is generated.

The pitch elongation amount ΔL of the mark 5 at this time is δt = ΔL / V, where δt is the delay time and V is the linear velocity of the intermediate transfer belt 10, and the period of the detection signal by the mark sensors 6A and 6B. Is Ca = Cb = T, the phase difference Cab is calculated by the following equation.
Cab = δt / T = ΔL / V · T (1)
Therefore, the phase difference Cab changes in proportion to the pitch elongation (change) ΔL.

The elongation change rate R is obtained by the following equation, where L is the distance between the mark sensors 6A and 6B.
R = ΔL / L = δt · V / L (2)
The actual belt linear velocity Vreal obtained by P / T using the pitch (scale pitch) P of the mark 5 is calculated by the following equation in consideration of the elongation of the scale.
Vreal = P (1 + R) / T (3)

The cumulative movement distance Lreal is calculated by multiplying the count value “N” of the detection signal by the mark sensor 6A or 6B by the scale pitch “P”.
Lreal = N · P + Σ {ΔL (k)} = N · P + Σ {P · R (k)}
= N · P {1 + Σ (P (k)} (4)
Thus, the amount obtained by adding the integral value of the elongation amount can be calculated as the actual cumulative moving distance.

In the control that does not consider the scale pitch error, the difference between the pulse interval Ca (n) or Cb (n) of the detection signal of one mark sensor 6 and the standard pulse interval C0 is feedback-controlled. A difference ΔV between the target speed Vref to be fed back and the actual speed Vreal is calculated by the following equation.
ΔV = Vref−Vreal
= Fc · P0 / C0−fc · Pa (n) / Ca (n) (5)
fc: counter clock P0: standard scale pitch C0: standard clock count of one cycle of detection signal of mark sensor,
Pa (n): Scale pitch with error added Ca (n): Real clock count of one cycle of detection signal of mark sensor

Next, based on the above description, the first and second embodiments of the endless moving member drive control device and the endless moving member speed control method according to the present invention will be described with reference to FIGS. This will be described with reference to FIG.
[First embodiment]
FIG. 1 is a block diagram showing the configuration of the first embodiment, which corresponds to an embodiment of the invention according to claims 1, 2, and 12-14. In FIG. 1, the same reference numerals are given to the portions corresponding to FIG. 4 described above.

In FIG. 1, the mark sensor 6, the mark counter 12, the fV conversion circuit 37, and the control controller 71 as a control means constitute the control device 70 shown in FIG. Further, the motor 7, the speed reducer 8 and the driving roller shown in FIG. 4 constitute driving means for rotating the intermediate transfer belt 10 which is an endless moving member.
A large number of marks 5 are provided on the outer peripheral surface of the intermediate transfer belt 10 so as to be continuous at a predetermined initial pitch P0 in the moving direction indicated by arrow F as shown in FIG. ing. In the vicinity of the scale forming portion of the intermediate transfer belt 10, a mark sensor 6 as shown in FIGS. 8B and 8C is fixedly fixed to the fixing portion of the image forming apparatus.

  When the driving roller 9 is rotated by the motor 7 and the intermediate transfer belt 10 rotates in the direction indicated by arrow F, the mark sensor 6 detects the mark 5 on the scale 250 as the intermediate transfer belt 10 moves. Then, a mark sensor signal (pulse signal) as shown on the upper side of FIG. 5 is output. The mark counter 12 counts the number of pulses of the mark sensor signal (the number of detected marks), and gives the count value to the controller 71 as belt surface position, that is, movement position (distance) information of the intermediate transfer belt 10.

Alternatively, the pulse signal Pe corresponding to the rotation angle, that is, the rotation amount of the motor 7 output from the rotary encoder 19 is used as a reference clock and counted by the mark counter 12 between the rising (or falling) edges of the pulse of the mark sensor signal. The integrated value of the count value may be given to the controller 71 as movement position information of the intermediate transfer belt 10.
On the other hand, the fV conversion circuit 37 is a signal conversion means, which receives a pulse signal Pe corresponding to the rotation amount of the motor 7 output from the rotary encoder 19, and sets its frequency (number of pulses per unit time) to the motor. 7 is output to the controller 71 after being converted into a shaft rotational speed signal.

Then, the control controller 71 serving as a control unit controls the driving force of the motor of the driving unit based on the rotational speed signal output from the fV conversion circuit 37 and the movement position information on the belt surface output from the mark counter 12. Then, feedback control is performed on the moving speed of the intermediate transfer belt 10 which is an endless moving member.
Therefore, the controller 71 of this embodiment includes a differential circuit 74 that takes a difference between a preset target position and movement position information from the mark counter 12, and a speed command generation that generates a speed command according to the difference. A speed command generating means comprising the unit 72, a differential circuit 75 for taking a difference between the speed command generated thereby and the rotational speed signal from the fV conversion circuit 37, and a torque command (drive) according to the difference Torque command generating means including a torque command generating unit 73 for generating (voltage), and the driving force of the motor 7 is controlled by the torque command generated thereby.

  Accordingly, the rotational speed of the motor 7 and the moving speed of the intermediate transfer belt 10 are controlled accordingly, and the result is fed back as the rotational speed by the rotary encoder 19 and the fV conversion circuit 37, and the mark sensor 6 and the mark counter. 12 is fed back as movement position information on the belt surface. Accordingly, the rotational speed is controlled with high accuracy so that the image transfer position of the intermediate transfer belt 10 always moves to a preset target position.

The control device 7 (FIG. 4) including the control controller 71 is totally controlled by a microcomputer (not shown).
In addition, although the example which uses the fV conversion circuit 37 as a means to detect the shaft rotational speed of the motor 7 based on the pulse signal Pe output from the rotary encoder 19 was demonstrated, it is not restricted to this, For example, 1 Speed detection with higher time resolution can be performed by obtaining the speed by measuring the time interval of the pulse edge for each pulse.

[Second Embodiment]
FIG. 2 is a block diagram showing the configuration of a second embodiment of the endless moving member drive control device and the speed control method of the endless moving member according to the present invention, and is an embodiment of the invention according to claims 3 to 8 and 15 to 17. It corresponds to. In FIG. 2, parts corresponding to those in FIGS. 1 and 6 described above are denoted by the same reference numerals, and description thereof is omitted.

  The second embodiment is different from the first embodiment shown in FIG. 1 described above in that a number of marks constituting the scale 250 on the intermediate transfer belt 10 are also described with reference to FIGS. Two mark sensors 6A and 6B are arranged at predetermined intervals along the moving direction of the intermediate transfer belt 10 (arrow F direction), and two phase counters 11A, 11A, In addition to the same configuration as the control controller 71 in the first embodiment described above, a target position correcting unit 77 is added to the controller 11 that is 11B, the phase difference calculating unit 13 and the control means 76 that is a control means. The output is input to the differential circuit 74. The mark counter 12 counts a mark sensor signal (pulse signal) that is a detection signal of one of the mark sensors (in the example shown in FIG. 2, the mark sensor 6A), and the count value is calculated as the belt surface position, that is, This is given to the controller 71 as movement position information of the intermediate transfer belt 10.

On the other hand, the detection signals Sa and Sb shown in FIGS. 9A and 9B by the two mark sensors 6A and 6B are input to the gates G of the phase counters 11A and 11B, respectively, and the rotary encoder 19 is used. The pulse signal Pe corresponding to the rotation amount of the motor 7 output from is input to the source S as a reference pulse.
Then, the phase counter 11A resets the count value at the rising edge of the detection signal Sa to return to 0, starts counting the pulse signal Pe again, and outputs the count value Na to the phase difference calculation unit 13. The phase counter 11B also resets the count value to 0 at the rising edge of the detection signal Sb, starts counting the pulse signal Pe again, and outputs the count value Nb to the phase difference calculation unit 13.

  The phase difference calculation unit 13 watches the count value Na or Nb of the phase counter that is reset earlier among the phase counters 11A and 11B, and then stores the count value when the other phase counter is reset. To do. The count value corresponds to the delay time δt in the above equation (1).

Thereafter, the count value immediately before the count value of the phase counter that was reset earlier is reset again is stored. The count value at this time corresponds to the cycle T of the detection signal Sa or Sb. Therefore, the phase difference Cab between the detection signals Sa and Sb described with reference to FIG. 9 can be easily calculated by calculating Cab = δt / T in (1) described above.
When calculating the phase difference Cab as the advance / delay of the detection signal Sa of the mark sensor 6A with respect to the detection signal Sb of the mark sensor 6B, the phase counter 11A is reset earlier when the pitch of the mark 5 increases. Therefore, when the lead phase difference is reached and the pitch of the mark 5 is reduced, the phase counter 11B is reset earlier and becomes a delayed phase difference.

Note that the phase difference calculation unit 13 may calculate the phase difference between the falling edges of the detection signals Sa and Sb.
This phase difference Cab is mainly caused by expansion / contraction of the intermediate transfer belt 10 due to a change in the pitch (interval) error when the mark 5 constituting the scale 250 shown in FIGS. Caused by.

In this embodiment, since the pulse signal Pe output from the rotary encoder 19 is used as the reference pulse of the phase counters 11A and 11B, the phase difference is calculated by the phase difference calculation unit 13 based on the rotation amount of the motor 7, that is, the position reference. Can be detected. Therefore, the phase difference indicating the pitch variation rate of the mark 5 can be detected without being affected by the moving speed of the intermediate transfer belt 10. Therefore, even when the moving speed of the intermediate transfer belt 10 is controlled to a plurality of different speeds, it is possible to always detect the phase difference, that is, the mark pitch fluctuation rate with the same accuracy.
However, this is not an essential requirement of the present invention. For example, a clock pulse that serves as a reference for the operation of a microcomputer that performs overall control of the control device 70 may be used as a reference pulse for the phase counters 11A and 11B. .

The controller 76 corrects the preset target position that increases linearly by the target position correction unit 77 using the phase difference Cab calculated by the phase difference calculation unit 13, and sets the difference between the corrected target positions. Input to the moving circuit 74. Subsequent processing in the controller 76 is the same as that in the controller 71 of the first embodiment.
That is, the differential circuit 74 takes the difference between the target position corrected by the target position correcting unit 77 and the movement position information from the mark counter 12. Then, the speed command generator 72 generates a speed command according to the difference, the difference between the speed command and the rotation speed signal from the fV conversion circuit 37 is taken by the differential circuit 75, and according to the difference. The torque command generator 73 generates a torque command (drive voltage), and controls the driving force of the motor 7 based on the generated torque command.

Accordingly, the rotational speed of the motor 7 and the moving speed of the intermediate transfer belt 10 are controlled accordingly, and the result is fed back as the rotational speed by the rotary encoder 19 and the fV conversion circuit 37, and the mark sensor 6A and the mark counter are fed back. 12 is fed back as movement position information on the belt surface, and is fed back as a phase difference (mark pitch fluctuation rate) by the mark sensors 6A and 6B, the phase counters 11A and 11B, and the phase difference calculation unit 13. Accordingly, the rotational speed is controlled with high accuracy so that the image transfer position of the intermediate transfer belt 10 always moves to a preset target position.
The control device 70 (FIG. 6) including the control controller 76 is also comprehensively controlled by a microcomputer not shown.

The two mark sensors 6A and 6B in this embodiment need to be fixed so that their distances do not fluctuate. Therefore, it is desirable that they are integrally supported by the same support member, such as a glass substrate. It is preferable to use a material having a small coefficient of thermal expansion.
The distance between the two mark sensors 6A and 6B is preferably shorter than the moving distance of the intermediate transfer belt 10 by one rotation of the rotating shaft of the motor 7.
In this embodiment as well, other speed detection means may be used in place of the fV conversion circuit 37 as in the case of the embodiment shown in FIG.

[Other Examples]
Here, an embodiment corresponding to claims 9 and 10 common to the endless moving member drive control apparatus of the first and second embodiments will be described.

In the second embodiment, when one of the mark sensors 6A and 6B corresponds to a mark discontinuous portion such as a portion where the mark 5 is missing or a joint of a scale, the mark detection signal Sb shown in FIG. The phase difference pulse becomes abnormally large and the phase comparison output increases rapidly. Means for detecting this can be provided to detect defects or joints in the mark 5.
In the example shown in FIG. 11, the phase difference is calculated based on the time difference between the falling edges of the detection signals Sa and Sb of the mark sensors 6A and 6B, but the phase difference pulse is an analog input when viewed as a signal whose duty changes as a PWM signal. Can be monitored. If the phase difference between the detection signals Sa and Sb of the two mark sensors 6A and 6B is monitored by a microcomputer, a mark discontinuity can be detected. In that case, the microcomputer also functions as a mark defect / seam detection means.

  Further, when the mark 5 is defective or the joint is located between the two mark sensors 6A and 6B, the detection signals of the mark sensors 6A and 6B are sequentially lost as shown in FIG. 12, and the phase difference pulse is abnormal. Or no longer output. Therefore, while this state is detected, the controller 76 shown in FIG. 2 stops feedback control of the moving speed of the intermediate transfer belt 10 based on the phase difference (referred to as “phase difference control stop section” in FIG. 12). As shown). Thereby, control due to an abnormal phase difference is prevented, and the control state can be maintained by continuing the control state immediately before that.

  It should be noted that three or more mark sensors can be provided so that even if a defect or joint of the mark 5 is located between the two mark sensors, it cannot be located between the other mark sensors. Accordingly, in the mark discontinuous portion, the mark sensor to be used can be switched, and the accurate phase difference can be continuously detected so that the feedback control of the moving speed of the intermediate transfer belt 10 does not have to be stopped.

  Furthermore, also in the first embodiment described above, when a mark discontinuity portion such as a portion where the mark 5 is missing from the mark sensor 6 or a joint of a scale is in a corresponding position, an interval is left in the mark detection signal. The count pulse of the mark counter 12 is lost, and accurate belt surface position (movement amount) information cannot be obtained. Therefore, for example, when the mark counter 12 shown in FIG. 1 measures the pulse period of the detection signal from the mark sensor 6 by counting the pulse signal output by the rotary encoder 19 or by counting the reference clock shown in FIG. The period T (n) is monitored by a microcomputer (not shown), and when it exceeds a preset value, it is determined that the mark is defective or a joint, and feedback control by the controller 71 is stopped. Control stability can be maintained if the immediately preceding control state is continued.

[Application example]
Here, although not an embodiment of the present invention, as an application example, when two mark sensors 6A and 6B are arranged as shown in FIG. 7, the two mark sensors 6A and 6B are identical to each other. By measuring the time difference for detecting the passage of the toner, the speed of the intermediate transfer belt 10 can be calculated with high accuracy.
As an example of the configuration, when the mark sensor 6B is on the upstream side in the moving direction (arrow F direction) of the intermediate transfer belt 10, the count value of the mark detection signal of the mark sensor 6B by the phase counter 11B shown in FIG. The multi-stage register is used as a delay memory to count the time for the number of marks between the two mark sensors 6A and 6B to pass.

When there are N marks between the mark sensors 6A and 6B, an N-stage register is used, and by a time T obtained by integrating N count values of detection signals from the mark sensor 6B,
V = (distance between sensors) / T
The speed V can be calculated by the following calculation.

In this case, the optimum value of the interval between the two mark sensors will be examined.
(1) Detection amplitude and reproducibility If the interval between the mark sensors is reduced, the observed phase difference is reduced. However, if the interval is increased, the measurable frequency is reduced by averaging the phase difference, and oscillation due to phase rotation occurs. A possibility arises. In order to correct the third-order component of the belt period, the interval between the mark sensors is preferably 50 mm or less.

(2) Detection sensitivity Even if the scale error is several tens of μm per rotation of the belt, the fluctuation that occurs within one pitch of the mark is 1 / number of marks (about 7000), so high sensitivity detection is required. Thus, the sensitivity increases as the interval between the mark sensors is increased.
The detection sensitivity x can be calculated by the following equation.
x = 7.85 / Nab (Nab: number of marks between mark sensor intervals)
When the interval is 20 mm, Nab = 118
x = 0.067 μm
Therefore, if there is an interval of 20 mm, the sensitivity is sufficient. Therefore, if the distance between the two mark sensors is D, it is appropriate to set the following range.
10mm <D <50mm

Although the embodiment in which the present invention is applied to the speed control of the intermediate transfer belt 10 of the tandem type color image forming apparatus shown in FIG. 3 has been described, the secondary transfer belt 24 and the photoreceptors 40Y, 40C, 40M, The present invention can be similarly applied to speed control of other belt-shaped or drum-shaped endless moving members such as 40K.
Also, images of transfer belts, intermediate transfer belts, photosensitive belts, paper transport belts, intermediate transfer drums, photosensitive drums, etc. in image forming apparatuses such as other electrophotographic color or monochrome copying machines, printers, facsimile machines, etc. The present invention can be similarly applied to the speed control of a belt-like or drum-like endless moving member related to formation.
Furthermore, the present invention can also be applied to speed control of an endless moving member in the form of a belt or drum that requires high-accuracy speed control in an inkjet color printer or other various devices.

  The present invention can be used for speed control of a belt-like or drum-like endless moving member that requires high-precision speed control in various devices. In particular, it is suitable for controlling the speed or position of an endless moving member such as a belt-shaped or drum-shaped transfer belt or a photosensitive member related to image formation of various image forming apparatuses with high accuracy. When applied to a color image forming apparatus, it is possible to prevent color misregistration and the like and always form a high-quality full-color image.

It is a block diagram which shows the structure of 1st Example of the endless moving member drive control apparatus by this invention and the speed control method of an endless moving member. It is a block diagram which similarly shows the structure of the 2nd Example. 1 is an overall configuration diagram of a mechanism unit showing an example of an image forming apparatus to which the present invention is applied. FIG. 4 is a schematic configuration diagram of a portion corresponding to the first embodiment of the endless moving member drive control device according to the present invention in the image forming apparatus shown in FIG. 3. 6 is a time chart showing a mark detection signal (mark sensor signal) by the mark sensor shown in FIG. 4 and a waveform of a reference clock for measuring the cycle thereof. FIG. 4 is a schematic configuration diagram of a portion corresponding to a second embodiment of the endless moving member drive control device according to the present invention in the image forming apparatus shown in FIG. 3.

It is explanatory drawing which expands and shows the example of the arrangement | positioning relationship between the mark 5 shown in FIG. 5, and the two mark sensors 6A and 6B. FIG. 6 is a diagram illustrating a configuration example of a scale and a mark sensor including a large number of marks provided on the outer peripheral surface of the intermediate transfer belt. It is a figure which shows the relationship between the waveform which shape | molded the output signal of two mark sensors 6A and 6B, and its phase difference. It is a figure for demonstrating the positional relationship of the mark detection area | region of two mark sensors 6A, 6B, and the mark detected by it. It is a timing chart for demonstrating a means to detect a mark discontinuity part from a phase difference pulse. It is a timing chart for demonstrating the case where control is stopped in a mark defective part.

Explanation of symbols

1: Main body 2: Paper feed table 3: Scanner 4: Automatic document feeder (ADF)
5: Mark (composing a scale) 6, 6A, 6B: Mark sensor 7: Motor 8: Reducer 9: Drive roller 10: Intermediate transfer belt (endless moving member)
11A, 11B: Phase counter 12: Mark counter 13: Phase difference calculation unit 15, 16: Driven roller 18: Image forming unit 19: Rotary encoder 20: Transfer device 21: Exposure device 22: Secondary transfer device 24: Secondary transfer belt

40Y, 40M, 40C, 40K: photoconductor 58: light shielding unit 60: charging device 61: developing device 62: primary transfer roller 63: photoconductor cleaning device 64: static eliminator 70: controller 71, 76: controller 72: Speed command generation unit 73: Torque command generation unit 74, 75: Differential circuit 77: Target position correction unit 110: Mark sensor housing 111: Light emitting element 112: Collimator lens
113 slit mask 114: light receiving window 115: light receiving element 250: scale

Claims (17)

An endless moving member drive control device comprising a belt-like or drum-like endless moving member and a driving means for rotating the endless moving member,
A plurality of marks are provided on the front or back surface of the endless moving member so as to be continuous at a predetermined interval over the moving direction,
A mark sensor for detecting the mark as the endless moving member moves,
A rotary encoder that outputs a pulse signal corresponding to a rotation angle of a shaft member that rotates in conjunction with the rotation of the endless moving member;
Signal conversion means for converting a pulse signal output from the rotary encoder into a rotation speed signal;
A counter that counts a mark detection signal output from the mark sensor and outputs movement position information of the endless moving member;
Control means for feedback-controlling the moving speed of the endless moving member by the driving means based on the rotational speed signal output from the signal converting means and the moving position information output from the counter is provided. Endless moving member drive control device. In the endless moving member drive control device according to claim 1,
The control means generates a speed command generating means for generating a speed command in accordance with a difference between a preset target position and the movement position information, and determines a difference between the speed command generated by the means and the rotational speed signal. An endless moving member drive control apparatus comprising: a torque command generation unit that generates a torque command in response to the torque command generated by the torque command generation unit. An endless moving member drive control device comprising a belt-like or drum-like endless moving member and a driving means for rotating the endless moving member,
A plurality of marks are provided on the front or back surface of the endless moving member so as to be continuous at a predetermined interval over the moving direction,
A plurality of mark sensors for detecting the marks are disposed at predetermined intervals along the moving direction of the endless moving member,
A phase difference calculating means for sequentially calculating a phase difference of mark detection signals output from the plurality of mark sensors as the endless moving member moves;
A rotary encoder that outputs a pulse signal corresponding to a rotation angle of a shaft member that rotates in conjunction with the rotation of the endless moving member;
Signal conversion means for converting a pulse signal output from the rotary encoder into a rotation speed signal;
Control means for feedback-controlling the moving speed of the endless moving member by the driving means based on the rotational speed signal output from the signal converting means and the phase difference calculated by the phase difference calculating means. An endless moving member drive control device. In the endless moving member drive control device according to claim 3,
The control means corrects a preset target position with a phase difference calculated by the phase difference calculation means, and generates a speed command according to the target position corrected by the target position correction means. Speed command generating means for generating torque command generating means for generating a torque command according to the difference between the speed command generated by the means and the rotational speed signal, and the torque command generated by the torque command generating means An endless moving member drive control device for controlling the drive force of the drive means. In the endless moving member drive control device according to claim 3,
Providing a counter that counts a mark detection signal output from any of a plurality of mark sensors and outputs movement position information of the endless moving member;
The control means corrects a preset target position with a phase difference calculated by the phase difference calculation means, a target position corrected by the target position correction means, and the movement position information. A speed command generating means for generating a speed command according to the difference; and a torque command generating means for generating a torque command according to a difference between the speed command generated by the means and the rotational speed signal. An endless moving member drive control apparatus, wherein the drive force of the drive means is controlled by a torque command generated by the generating means. In the endless moving member drive control device according to any one of claims 3 to 5,
The phase difference calculating means measures a time difference between rising edges or falling edges of mark detection signals output from the plurality of mark sensors, by measuring a pulse signal output from the rotary encoder as a reference clock. An endless moving member drive control device characterized by being means for calculating In the endless moving member drive control device according to any one of claims 3 to 6,
The endless moving member drive control device, wherein the plurality of mark sensors are integrally supported by the same support member. In the endless moving member drive control device according to any one of claims 3 to 7,
The endless moving member drive control device, wherein an interval between the plurality of mark sensors is shorter than a moving distance of the endless moving member by one rotation of a motor of the driving means. In the endless moving member drive control device according to any one of claims 3 to 8,
An endless moving member drive control device, comprising: a mark defect / seam detection means for detecting a defect or a joint of a plurality of consecutive marks at the predetermined interval based on the phase difference calculated by the phase difference calculation means. In the endless moving member drive control device according to claim 9,
When it is detected by the mark defect / seam detection means that the mark defect or the joint is located between the plurality of mark sensors, the control means performs feedback control of the moving speed of the endless moving member. An endless moving member drive control device characterized by stopping.   An endless moving member drive control device according to claim 1, wherein the endless moving member includes a transfer belt, an intermediate transfer belt, a photosensitive belt, a paper transport belt, an intermediate transfer drum, and a photosensitive drum. An image forming apparatus characterized by being at least one of the above. A moving speed control method for rotating a belt-shaped or drum-shaped endless moving member by a driving means,
A plurality of marks are provided on the front or back surface of the endless moving member so as to be continuous at a predetermined interval over the moving direction,
As the endless moving member moves, the plurality of marks are detected by a mark sensor,
Obtaining movement position information of the endless moving member from a mark detection signal output from the mark sensor;
A pulse signal corresponding to the rotation angle of the shaft member is output by a rotary encoder attached to the shaft member rotating in conjunction with the rotation of the endless moving member,
The pulse signal is converted into a rotation speed signal,
A moving speed control method for an endless moving member, wherein the moving speed of the endless moving member by the driving means is feedback-controlled by the rotation speed signal and the moving position information. In the moving speed control method of the endless moving member according to claim 12,
The pulse signal output from the rotary encoder is counted between the rising or falling edges of the mark detection signal output from the mark sensor, and the moving position information of the endless moving member is obtained by the integrated value of the count value. A moving speed control method for an endless moving member. In the moving speed control method of the endless moving member according to claim 12 or 13,
A speed command is generated according to a difference between a preset target position and the movement position information, a torque command is generated according to a difference between the speed command and the rotation speed signal, and the driving is performed according to the torque command. A moving speed control method for an endless moving member, characterized in that the driving force of the means is controlled. A moving speed control method for rotating a belt-shaped or drum-shaped endless moving member by a driving means,
A plurality of marks are provided on the front or back surface of the endless moving member so as to be continuous at a predetermined interval over the moving direction,
Detecting the plurality of marks by a plurality of mark sensors arranged at predetermined intervals along the moving direction of the endless moving member;
With the movement of the endless moving member, the phase difference between the mark detection signals output from the plurality of mark sensors is sequentially calculated,
A pulse signal corresponding to the rotation angle of the shaft member is output by a rotary encoder attached to the shaft member rotating in conjunction with the rotation of the endless moving member,
The pulse signal is converted into a rotation speed signal,
A method for controlling the moving speed of the endless moving member, wherein feedback control is performed on the moving speed of the endless moving member by the driving means based on the rotation speed signal and the phase difference sequentially calculated. In the moving speed control method of the endless moving member according to claim 15,
The phase difference is calculated by measuring a time difference between rising edges or falling edges of mark detection signals output from the plurality of mark sensors, using a pulse signal output from the rotary encoder as a reference clock. A moving speed control method for the endless moving member. The moving speed control method for an endless moving member according to claim 15 or 16,
Counting a mark detection signal output from any one of the plurality of mark sensors to obtain movement position information of the endless moving member,
A preset target position is corrected by the phase difference calculated sequentially, a speed command is generated according to a difference between the corrected target position and the movement position information, and the speed command and the rotation speed signal are A moving speed control method for an endless moving member, wherein a torque command is generated according to the difference, and the driving force of the driving means is controlled by the torque command.

Images