JP4672583B2 - Control method for paper transport device provided with transport paper displacement detection device - Google Patents

Description

The present invention relates to a control method for a paper transport device including a displacement detection device for transport paper such as printing paper or plate-making paper.

  A paper transport device that transports a large number of papers sequentially is used in various machines such as stencil printers that transport plate-making paper and printing paper, photographic printers, photocopiers, and automatic readers that transport mail and forms. These paper transport devices are usually provided with a paper detection device for detecting the presence or absence of paper to be transported and the movement state of paper such as a jam.

  FIG. 14 shows an example of a conventional paper conveyance device and paper detection device. In FIG. 14, the conveyance means includes a pair of upper and lower conveyance rollers 101 and 102, and a lower drive-side conveyance roller 102. Are coupled to the motor 104 via the power transmission mechanism 103. Conventionally, a transmissive optical sensor 105 that detects light shielding is used as the paper detection device. The optical sensor 105 includes a light emitting unit 111 and a light receiving unit 112 arranged with a sheet conveyance path interposed therebetween, and the light receiving unit 112 is connected to the controller 120. On the other hand, the motor 104 is provided with an encoder 123 that detects the rotation speed and rotation amount (rotation angle) of the motor 104 and is connected to the controller 120. Although the light from the light emitting unit 111 is blocked by the paper P, the presence of the paper P can be detected. In addition to detecting the presence of the paper P, the following paper state or requirement is detected. It has become.

(1) Paper Length The light from the light emitting unit 111 is blocked by the paper P being conveyed, thereby detecting the front end of the paper P in the conveyance direction F. Thereafter, the light from the light emitting unit 111 is detected by the light receiving unit 112. By receiving light again, the rear end of the paper P is detected, and the rotation amount (rotation angle) of the motor 104 is detected by the encoder 123 from the time when the front edge of the paper P is detected to the time when the rear edge is detected. Is calculated (see Patent Document 1, etc.).

(2) Skew In order to detect the situation in which the paper P is transported obliquely with respect to the transport direction F, a predetermined interval is provided in the direction orthogonal to the transport direction F of the paper P as shown in FIG. A plurality of transmissive photosensors 200-1, 2, 3 are arranged, and the skew of the paper P is detected based on the difference in detection timing of each photosensor 200-1, 2, 3 (Patent Document 2).
JP 2001-232922 A JP 2001-168221 A

  As shown in FIGS. 14 and 15, the detection method using an optical sensor using light blocking and transmission has the following problems.

(1) It is difficult to detect the slip amount.
Paper dust or the like may adhere to the outer peripheral surface of the transport roller 102 or the roller may be worn, so that the paper may slip on the outer peripheral surface of the roller. Tends to be smaller than the expected paper feed amount. With respect to such a slip phenomenon, the transmission type optical sensor can detect the slip phenomenon itself as long as the length of the conveyance paper is uniform, but it can detect the slip amount accurately. It is difficult.

(2) Inaccuracy in detection of paper length Since it is difficult to accurately detect the slip amount with a transmission type optical sensor as described above, slipping occurs when papers of different lengths are mixed. When the phenomenon occurs, an error occurs in the accumulated length, and the paper length cannot be accurately detected.

(3) The skew detection speed is slow As shown in FIG. 15, in the method of detecting skew by the difference in detection timing of the plurality of optical sensors 200-1, 2, and 3, when the paper P is skewed, The time from the detection timing of the optical sensor 200-1 that detects the front edge of the paper the fastest to the detection timing of the optical sensor 200-3 that detects the latest or the intermediate optical sensor 200-2 is required, and the detection speed becomes slow.

(Object of invention)
An object of the present invention is a displacement detection device that can easily detect a slip amount and a two-dimensional displacement amount of a sheet, and ensures slip amount, sheet position, transport speed, displacement amount and skew even during a slip. Disclosed is a displacement detection device and a method for controlling a sheet conveying device including the displacement detection device.

According to a first aspect of the present invention, a light emitting unit that irradiates light from an LED light source onto a surface of a paper being transported at a predetermined position on a paper transport path, and a paper surface within a certain detection region where the light is irradiated A light receiving unit having an image sensor that receives reflected light to read a light / dark pattern and converts it into an electrical signal, and a control device connected to the light receiving unit to receive the electrical signal of the light / dark pattern; The image sensor is configured to read a light and dark pattern in the detection area of a sheet being conveyed periodically, and detects a displacement of a conveyance sheet, a conveyance unit that conveys the sheet, and drives the conveyance unit a drive motor, the control method of the paper conveying apparatus wherein the control unit compares the position of intersection of the plurality of light-dark pattern read periodically by the image sensor, the paper Is configured to calculates the amount of displacement, by the control device, wherein when the paper detection region of the displacement detecting device does not exist, as the first feedback control, the rotational speed of the drive motor at a constant value When the sheet exists in the detection area, the second feedback control is performed based on the sheet moving speed calculated from the displacement amount in the sheet conveying direction detected by the displacement detection device. The rotational speed of the drive motor is controlled so that the moving speed of the transport surface becomes the target speed . Preferably, as in the second aspect of the present invention, the second feedback control is performed by using the paper whose travel speed of the transport surface of the transport means is calculated from the displacement amount in the transport direction of the paper detected by the displacement detection device. The rotational speed of the drive motor is controlled so as to have a value substantially corresponding to the moving speed of the motor.

  According to the above configuration, the rotation speed of the drive motor is changed by the second feedback control so as to substantially correspond to the conveyance speed of the sheet only when the sheet is detected, so that the rotation of the motor is meaningless when the sheet is not detected. It is not necessary to change it, and the control of the rotational speed of the motor by the control device is not complicated, and the service life of the drive motor is increased. Further, since the control (change) always starts from the constant motor rotation speed when the sheet non-detection state changes to the sheet detection state, the motor rotation control can be started promptly.

According to a third aspect of the present invention, in the method for controlling a paper conveying device according to the first or second aspect, the control device causes the paper to be present from a state in which no paper is present in the detection area of the displacement detecting device. , The moving speed of the conveying surface of the conveying means is compared with the paper moving speed detected by the displacement detecting device for a predetermined time, and the moving speed of the conveying surface of the conveying means and the moving speed of the paper are compared. When the difference is larger than a predetermined value, the first feedback control is continued, and when the difference is less than the predetermined value, the second feedback control is switched.

  According to the above configuration, it is possible to avoid a situation in which the rotational speed of the drive motor changes drastically at the time of switching from the first feedback control when the paper is not detected to the second feedback control when the paper is detected. The above control can be switched smoothly.

According to a fourth aspect of the present invention, in the method for controlling a paper conveyance device according to any one of the first to third aspects, the displacement detection device can read a light / dark pattern on a conveyance surface of the conveyance unit. Is disposed above the conveying means, the conveying means is idled by a predetermined displacement amount, the displacement detecting device detects the displacement amount of the conveying surface of the conveying means, and the detected displacement amount is used as the conveying means. When the detection error occurs between the detected displacement amount and the predetermined displacement amount, the detected displacement amount is corrected to the same value as the predetermined displacement amount. ing.

  According to the above configuration, the measurement accuracy of the displacement detection device itself can be easily and accurately corrected when the displacement detection device is installed. That is, in the displacement detection device that receives the LED light reflected from the paper surface and reads the light / dark pattern, if the distance (height) or the arrangement angle from the paper surface to the light receiving unit is different, the paper quality and the paper surface pattern, etc. The amount of reflection of LED light changes, the measurement value has an error, and the reading accuracy changes. However, by correcting the accuracy of the displacement detection device itself, the light receiving unit is arranged in any position and at any angle. Therefore, accurate displacement amount detection can be performed.

According to a fifth aspect of the present invention, in the method for controlling a paper conveying apparatus according to any one of the first to fourth aspects, the conveying means is a conveying roller.

According to a sixth aspect of the present invention, in the method for controlling a paper conveying device according to any one of the first to fourth aspects, the conveying means is a conveying belt wound around a plurality of rollers.

According to a seventh aspect of the present invention, in the method for controlling the paper conveying device according to the fifth aspect , a mark indicating a reference position of one rotation of the conveying roller is attached, and the conveying roller is rotated once by the displacement detecting device. The amount of displacement in the circumferential direction of the mark is detected, and the detected amount of displacement is compared with the true total length of the transport roller obtained by calculation, and between the detected displacement amount and the true total length. When a detection error has occurred, the detected displacement is corrected to the same value as the true total circumference.

  According to the above configuration, in the paper transport device using the transport roller as the transport means, it is possible to easily and accurately correct the measurement accuracy when the displacement detection device is installed.

According to an eighth aspect of the present invention, in the method for controlling a paper conveying device according to the sixth aspect , the conveying belt is provided with a mark indicating a reference position of one cycle of the conveying belt, and the conveying belt is rotated around the conveying belt. A displacement detection device detects a displacement amount of the mark, compares the detected displacement amount with a true full length of the transport belt obtained by calculation, and a detection error is detected between the detected displacement amount and the true full length. When this occurs, the detected displacement is corrected to the same value as the true full length.

  According to the above configuration, in the paper conveying apparatus using the conveying belt as the conveying means, the measurement accuracy can be corrected easily and accurately when the displacement detecting device is installed.

According to a ninth aspect of the present invention, in the method for controlling a paper conveying device according to any one of the first to third aspects, the light / dark pattern of the paper is read by the reading device and is stored in the storage unit of the control device as an original light / dark pattern. Stores and reads the light / dark pattern of the paper being conveyed by the displacement detection device, compares the read light / dark pattern with the original light / dark pattern, and recognizes that the light / dark pattern is out of a predetermined range of identity. By doing so, a paper abnormality is detected.

  According to the above-described configuration, it is possible to quickly detect an abnormality of a sheet, for example, mixing of a defective printing sheet, a blank sheet, another type of sheet, and the like, and it is also possible to detect a double feed of sheets.

According to a tenth aspect of the present invention, in the method for controlling a paper conveyance device according to any one of the first to third aspects, the light and dark patterns of the sequentially conveyed paper are read by the displacement detection device, respectively, from any paper The read light / dark pattern is compared with the light / dark pattern of the paper read before the paper, and the abnormality of the paper is detected by recognizing that the light / dark pattern is out of a predetermined range of identity.

  According to the above configuration, since it is not necessary to use a reading device such as a scanner, the structure can be simplified and the cost can be reduced.

[First embodiment of the present invention]
FIG. 1 to FIG. 11 show a first embodiment of a paper transport device provided with a transport paper displacement detection device according to the present invention, and will be described below with reference to the drawings.

(Outline of paper transport device)
FIG. 1 is a schematic diagram of a main part of a sheet conveying apparatus including a displacement detection device. For convenience of explanation, the upstream side (conveying start end side) of the conveying direction F of the sheet P is “rear side”, and the sheet conveying direction F Hereinafter, the downstream side (conveyance end side) is referred to as “front side”, and the paper width direction (horizontal direction orthogonal to the paper conveyance direction F) is referred to as “left-right direction”.

  As a conveying means, a pair of conveying rollers 1 and 2 are vertically arranged opposite to each other, and the driving conveying roller 2 arranged on the lower side outputs the output of the driving motor 5 via the belt transmission mechanism 7. When the drive motor 5 rotates in conjunction with the shaft 6 and the drive motor 5 rotates, the drive roller 2 on the upper side is also driven in the direction of arrow R2 at the same time. That is, the sheet P is sandwiched between the upper and lower transport rollers 1 and 2 and is rotated in the R1 and R2 directions so that the sheet P is transported in the transport direction F.

  The drive motor 5 is connected to a control device (controller) 50, and is configured such that driving, stopping, and rotation speed are controlled by a control signal output from the control device 50.

  The displacement detection device 41 is arranged on the conveyance direction F side with respect to the conveyance rollers 1 and 2 and is located above the conveyance path of the paper P. The displacement detection device 41 is electrically connected to the control device 50 and detects various types of detected paper. A value signal is input to the control device 50.

  The drive motor 5 is provided with an encoder 5 that detects the rotation amount (rotation angle) of the output shaft 6. The encoder 5 includes, for example, a rotating plate 21 that rotates integrally with the output shaft 6, and the rotating plate 21. The rotating disk 21 is formed with a plurality of slits 23 at equal intervals in the circumferential direction, and these slits are detected by the detecting unit 22. Is to be detected. The detection unit 22 is electrically connected to a control device (controller) 50, and inputs the detected rotation amount (rotation angle) of the drive motor to the control device 50.

(Details of displacement detector)
FIG. 3 is a simplified perspective view of the displacement detection device 41. The displacement detection device 41 includes a light emitting unit 44 that incorporates an LED light source 45 and a light receiving unit 47 that incorporates an image sensor 48. The controller 50 is electrically connected. If necessary, a lens 46 is disposed in front of the LED light source 45 in the light emitting unit 44, and a lens 49 is also disposed below the image sensor 48 in the light receiving unit 47.

  The light emitting unit 44 is installed at a predetermined distance (for example, 7 mm to 10 mm) and a predetermined angle from the paper P in the transport path, and irradiates the LED light from the LED light source 45 onto the paper P through the lens 46. It is like that. The irradiation area S and the first displacement detection device 41 shown on the paper P are exaggerated with dimensions larger than the actual size in order to facilitate understanding thereof.

  The light receiving unit 47 is arranged at a predetermined distance (for example, 5 mm to 10 mm) from the paper P in the transport path. In particular, the image sensor 48 is arranged so as to be substantially parallel to the paper. The LED light reflected from the surface of P is received by the image sensor 48 via the lens 49, the imaged light / dark pattern is read, converted into an electrical signal, and input to the control device 50. The reading area B of the paper P by the image sensor 48 is shown in a substantially square shape in the irradiation area S. The bright and dark patterns are formed in a wide variety of ways, not only on the surface of the paper P, but also on the surface irregularities, paper fiber patterns, and unevenness that exist on ordinary white paper. Is.

  The image sensor 48 is a matrix in which a large number of image sensor pixels that detect the brightness (brightness) of light are arranged in a matrix. For example, 30 × 30 = 900 pixels (1 pixel = 1/800 inch) is formed in a square shape. The light and dark patterns in the reading area B can be read (photographed).

  Further, the image sensor 48 is set so as to periodically read the light / dark pattern of the reading region B on the paper P being conveyed, and the detection cycle is set to 130 μsec, for example. Note that this detection cycle can be changed as appropriate according to the type of paper, and can be changed, for example, to a maximum of about 81 μsec. Also, 1 pixel = 1/800, which is a reference for resolution, can be appropriately changed.

  By such a displacement detection device 41, the displacement amount (movement amount), movement speed, slip, slip amount, skew, skew angle, and sheet length of the sheet P moving in the conveyance path are detected. Of course, the presence or absence of the paper P can also be detected.

(Control content)
In order to control the drive and stop of the drive motor 5 and the rotational speed, the control device incorporates a program for performing the following steps, for example.

(1) In FIGS. 2 and 3, when the paper P does not exist in the detection area B of the displacement detection device 41, the rotation speed of the drive motor 5 is maintained at a constant value as the first feedback control, and the detection area When the sheet P exists in B, as the second feedback control, the movement speed (circumferential speed) of the outer peripheral transport surface of the transport roller 2 is the amount of displacement in the transport direction F of the paper P detected by the displacement detection device 41. The rotational speed of the drive motor 5 is controlled so that the value substantially corresponds to the moving speed of the paper P calculated from the above.

(2) In addition to the above control, the movement of the outer peripheral conveying surface of the conveying roller 2 for a predetermined time after the transition from the state in which the sheet P does not exist in the detection area B of the displacement detection device 41 to the state in which the sheet P exists. The speed is compared with the sheet movement speed in the conveyance direction F detected by the displacement detection device 41. When the difference between the movement speed of the outer peripheral conveyance surface of the conveyance roller 2 and the sheet movement speed is larger than a predetermined value, A control method for a sheet conveying device, characterized in that the first feedback control is continued and is switched to the second feedback control when the first feedback control is below a predetermined value.

(3) The light and dark patterns of the sequentially conveyed paper are read by the displacement detection device, the light and dark patterns read from an arbitrary paper P are compared with the light and dark patterns of the paper P read before the paper, and the both light and dark patterns are compared. By recognizing that the pattern is outside the range of the predetermined identity, the abnormality of the paper P is detected.

[Detection of moving amount and moving speed in transport direction]
FIG. 3 shows a method for detecting the movement amount and movement speed of the paper P in the transport direction F, and the upper and lower stages show states before and after one reading cycle by the image sensor 48. For example, if the position of the paper P shown in the upper row is the nth reading position by the displacement detection device 41, the position of the paper P shown in the lower row indicates the (n + 1) th reading position one cycle after the position shown in the upper row. ing.

  In FIG. 3, the light and dark patterns of the reading area B of the paper P at the position shown in the upper stage and the light and dark patterns of the reading area B of the paper P at the position shown in the lower stage are read by the image sensor 48 and converted into electric signals. Then, it is input to the control device 50, the displacement of the common part of both light and dark patterns is calculated, and the movement amount and movement speed of the paper P are detected.

  FIG. 4 shows an example of a bright and dark pattern formed on the image sensor 48 in an easy-to-understand manner. The upper part of FIG. 4 corresponds to the upper part of FIG. 3, and the reading area at the n-th reading position. 4 shows the light / dark pattern of B, and the lower part of FIG. 4 corresponds to the state of the lower part of FIG. 3, and shows the light / dark pattern of the reading region B at the (n + 1) th reading position after one cycle. The common part of the light / dark pattern is temporarily indicated by a triangle T (1,2). As shown in the lower part, the position of the common part (shaded triangle) T1 at the time of the n-th reading and the position of the common part T2 (black triangle) at the time of the n + 1-th reading are the same reading area. The amount of movement A1 (= A) in the conveyance direction F of the paper P in a predetermined cycle can be obtained from the difference D1 in the conveyance direction of T1 and T2 by comparing on the two-dimensional coordinates in B. Further, the moving speed of the paper P can be obtained from the moving amount A1 (D1) and a predetermined period (time).

  If the displacement amount D1 (movement amount A1) thus determined is the same as the displacement amount (movement amount) corresponding to the preset movement speed, the movement amount and movement speed of the paper P in the transport direction F are: It can be recognized that the normal value set in advance is maintained.

(Slip detection)
5 and 6 show a case where the paper P is completely stopped due to slip, and FIGS. 7 and 8 show a case where the paper P is moving in a slip state. 7 shows the same relationship as the relationship between the upper and lower steps in FIG. 3, and the upper and lower steps in FIGS. 6 and 8 show the same relationship as the relationship between the upper and lower steps in FIG. .

  In FIG. 5, when the paper P is completely stopped due to the slip, the paper P does not move forward and stops from the n-th reading at the upper stage to the n + 1-th reading at the lower stage. ing.

  Therefore, as shown in FIG. 6, the common portions T1 and T2 are not displaced between the common portion T1 at the time of the upper nth reading and the common portion T2 at the time of the lower (n + 1) th reading. The displacement amounts of the common portions T1 and T2 are zero. When such a displacement amount 0 is detected, it is recognized that the sheet P is completely stopped due to slipping, and for example, the printing press is stopped, and maintenance of the conveying means is performed.

  On the other hand, in FIG. 7, when the paper P is moving in a slip state, the paper P is normal for a period from the n-th reading at the upper stage to the n + 1-th reading at the lower stage. It moves with a movement amount A2 smaller than the movement amount A1.

  Accordingly, as shown in FIG. 8, a displacement amount D2 between the common portion T1 at the time of the n-th reading in the upper stage and the common portion T2 at the time of the (n + 1) -th reading is obtained, and this is calculated as a normal displacement set in advance. By comparing with the amount D1, the slip amount in a predetermined cycle can be obtained. In this case, for example, the rotational speed of the drive motor 5 in FIG. 1 is increased according to the obtained slip amount.

(Detection of paper length)
FIG. 9 shows a paper length detection method. The upper part shows a state at the start of length detection, and the lower part shows a state at the end of length detection. At the time of starting the upper length detection, the front end of the paper P is detected by the image sensor 48, and thereafter, as indicated by the phantom line in the lower stage, the reading area B (B ′) is read for each cycle. By determining the amount of displacement of the common portion, the amount of movement of the paper P for each period is detected. Then, when the trailing edge of the paper P is detected, the length L1 in the transport direction F of the paper P is obtained by integrating the displacement amount of the common part detected for each cycle.

  In this length detection method, even if the paper P slips, the amount of displacement of the common portion for each period changes according to the slip amount. Therefore, even if slip occurs, the paper length L1 is accurately obtained. be able to.

(Detect paper skew)
10 and 11 show a method for detecting the skew of a sheet. The upper and lower stages of FIG. 10 show the same relationship as the upper and lower stages of FIG. 3, and the upper and lower stages of FIG. 4 shows the same relationship between the upper and lower stages of FIG.

  That is, in FIG. 10, the left and right applied pressures or frictional forces of the rollers or the like are changed during one cycle or several cycles from the nth reading position in the upper stage to the (n + 1) th reading position shown in the lower stage. The paper P may be skewed due to a difference or the like.

  In the lower part of FIG. 11, when the paper P is skewed, the common portion T1 is displaced to T2 as the paper P is skewed. Specifically, the common portion T1 is displaced by a displacement amount D2 in the paper conveyance direction F, and is also displaced by a displacement amount E2 in a direction perpendicular to the conveyance direction F. The displacement direction and the displacement amount of the paper P are detected from the displacement amount D2 in the transport direction F and the displacement amount E2 in the direction perpendicular to the transport direction F. That is, the skew state of the paper P itself can be detected, and the skew angle θ and the displacement amount in the skew direction can also be detected.

  If skew of the paper P is detected as described above, for example, the printing machine is stopped.

[Detection of presence of paper and control of rotation speed of drive motor]
The rotational speed of the drive motor 5 is controlled based on the contents of the control according to various conditions of paper conveyance. Hereinafter, the control method will be summarized based on the relationship with the displacement detection device 41.

(1) According to the above control content (1), when the sheet P does not exist in the detection area B of the displacement detection device 41 in FIG. 2, the rotation speed of the drive motor 5 is kept constant by the first feedback control. Keep in value. That is, when the sheet is not detected, the drive motor 5 is rotated at a preset constant rotation speed, and thereby the transport roller 2 is rotated so as to have a preset movement speed.

  On the other hand, when the paper P is fed into the detection area B and the presence of the paper P is detected by the displacement detection device 41, the moving speed (circumferential speed) of the outer peripheral transport surface of the transport roller 2 is determined by the second feedback control. The rotational speed of the drive motor 5 is controlled so as to have a value substantially corresponding to the moving speed of the paper P calculated from the displacement amount in the transport direction F of the paper P detected by the displacement detector 41. That is, the transport roller 2 is rotated so that the moving speed is substantially the same as the actual moving speed of the paper P.

  As a result, the rotational speed of the motor 5 is not changed insignificantly when no paper is detected, the rotational speed control of the drive motor by the control device 41 is not complicated, and the service life of the drive motor is extended. Further, when the paper non-detection state changes to the paper detection state, the control (change) always starts from the constant rotation speed of the motor 5, so that the rotation control of the drive motor 5 can be started promptly.

(2) In addition to the above control, according to the control content (2) described above, after the transition from the state in which the paper P is not present in the detection area B of the displacement detection device 41 to the state in which the paper P is present, The moving speed of the outer peripheral conveying surface of the conveying roller 2 is compared with the paper moving speed detected by the displacement detection device, and the difference between the moving speed of the conveying outer peripheral surface of the conveying roller 2 and the paper moving speed is a predetermined value. When it is larger, the first feedback control is continued, and when it is less than a predetermined value, the second feedback control is switched.

  As a result, when the first feedback control at the time of non-detection of paper is switched to the second feedback control at the time of paper detection, a situation in which the rotational speed of the drive motor 5 changes greatly can be avoided. The above control can be switched.

(3) Further, according to the control content (3) described above, the light and dark patterns of the sequentially conveyed paper are read by the displacement detection device, and the light and dark patterns read from an arbitrary paper are read from the paper read before the paper. By comparing the light and dark pattern with the light and dark pattern and recognizing that the light and dark pattern is out of a predetermined range of identity, an abnormality in the paper is detected.

[Second embodiment of the present invention]
FIG. 12 shows a second embodiment of the sheet conveying apparatus provided with the displacement detecting device 41 according to the present invention. The structure different from that of the first embodiment shown in FIG. 1 is divided into left and right so as to have a space portion in the central portion in the axial direction, and a displacement detection device 41 is arranged in the central space portion so as to be positioned almost directly above the drive-side transport roller 2. Yes. In addition, a linear mark T extending in the axial direction, for example, is attached to the outer peripheral conveyance surface of the drive side conveyance roller 2 in order to directly detect one rotation of the drive side conveyance roller 2 by the displacement detection device 41. Other structures are the same as those of the first embodiment shown in FIG. 1, and the same components are denoted by the same reference numerals and description thereof is omitted.

  If the displacement detection device 41 is arranged directly above the driving-side conveyance roller 2 as in the configuration of FIG. 12, the detection accuracy of the conveyance state of the paper P by the displacement detection device 41 is improved. That is, the transported paper P is in a stable state where the flutter is the smallest and the flatness is maintained at the portion sandwiched between the upper and lower transport rollers 1 and 2 (nip portion), and this portion is detected. Since the light and dark pattern on the paper surface is detected as the area, for example, the light and dark pattern on the paper surface is accurately compared with the case where the displacement detection device 41 is arranged on the transport direction F side of the transport roller 2 as shown in FIG. The detection accuracy can be improved.

  The displacement detection device 41 differs in the sharpness of the brightness pattern of the reflected LED light depending on the height from the paper surface, which may cause an error in detection accuracy. By using the mark T attached to the roller 2, it is possible to easily adjust the detection accuracy when the displacement detector 41 itself is installed.

  That is, first, the radius (or diameter) of the driving-side transport roller 2 is measured in advance by a measuring device such as a caliper, a micrometer, or an electronic image measuring device, and is calculated from the measured radius (or diameter). The true total length C1 of the outer peripheral conveyance surface of the driving side conveyance roller 2 is obtained.

  Next, after the displacement detection device 41 is installed at a predetermined position as shown in FIG. 12, the drive-side transport roller 2 is idled without transporting the sheet, and the mark T passing periodically through the upper end of the transport roller 2 is displaced. Detected by the detection device 41, thereby detecting the movement amount C <b> 2 of the outer peripheral conveyance surface in one rotation of the conveyance roller 2. Then, the detected movement amount C2 is compared with the true total circumference length C1, and if there is a difference, the movement amount C2 is corrected so as to coincide with the true total circumference length C1.

[Third embodiment of the present invention]
FIG. 13 shows a third embodiment of a sheet conveying apparatus provided with a displacement detecting device 41 according to the present invention. The structure different from the first embodiment shown in FIG. A belt conveyance device 60 having a mechanism 61 is provided, and a displacement detection device 41 is disposed directly above the belt conveyance mechanism 60. Other structures are the same as those of the first embodiment shown in FIG. 1, and the same components are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 13, a belt conveying device 60 is composed of a pair of front and rear rotating rollers 62, 63, a conveying belt 64 wound around both rollers 62, 63, and the like. It is linked to the output shaft of the motor 5 through a transmission mechanism.

  The suction mechanism 61 includes a suction box 65 having a number of suction holes at the upper end, and a suction fan 66 connected to the suction box 65 via a duct or the like. A number of suction holes are also formed in the transport belt 64, and the paper P on the transport belt 64 is sucked by the suction box 65 so that the paper P is attracted to the transport belt 64 and transported in the transport direction F. ing.

  Although not shown, a linear mark T similar to the mark T shown in FIG. 12 is used on the outer peripheral conveyance surface of the conveyance belt 64 in order to directly detect the movement amount of the circumference of the conveyance belt 64 by the displacement detection device 41. Is attached. In the case of the conveyor belt 64, the entire circumference of the conveyor belt 64 is measured in advance, the conveyor belt 64 is rotated without conveying the paper P, and the mark T that periodically passes through the detection range is displaced. By detecting by the detection device 41, the movement amount of the outer peripheral conveyance surface in one circumference of the conveyance belt 64 is detected. Then, the detected movement amount is compared with the true total circumference of the conveyor belt 64, and when there is a difference, the detected movement amount is corrected so as to coincide with the true total circumference.

[Other embodiments]
(1) In the first embodiment, as a method of detecting a paper abnormality, the light and dark patterns of the paper P that are sequentially conveyed are read by the displacement detector 41, and the light and dark patterns read from any paper P are read. When abnormalities of the paper such as white paper and printing failure are detected by comparing with the light and dark pattern of the paper P read before the paper P, when a reading device such as a scanner can be used. Then, the light / dark pattern of the paper P is read by a reading device such as a scanner, and is stored as an original light / dark pattern in the storage unit of the control device. Then, in the paper transporting operation, the light and dark pattern of the paper P being transported is read by the displacement detection device 41, and the read light and dark pattern is compared with the original light and dark pattern, and both the light and dark patterns have a predetermined identity. By recognizing that it is out of range, an abnormality of the sheet is detected.

  The displacement detection device according to the present invention and the control method of the paper conveyance device provided with the displacement detection device include a stencil printing machine, a photo printing machine, a copying machine, or a postal item or a form for conveying a stencil sheet or printing paper. It can be used for various machines such as an automatic reader.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a simplified perspective view showing a first embodiment of a sheet conveying apparatus provided with a displacement detection device according to the present invention. FIG. 2 is a schematic side view of the sheet conveying device in FIG. 1. FIG. 6 is an explanatory diagram illustrating a method for detecting a moving amount and a moving speed of a sheet. It is a figure which shows the change of the light-and-dark pattern by the image sensor corresponding to FIG. It is explanatory drawing which shows the detection method when a paper stops by a slip. It is a figure which shows the change of the light-and-dark pattern by the image sensor corresponding to FIG. It is explanatory drawing which shows the detection method when the paper is moving in the slip state. It is a figure which shows the change of the light-and-dark pattern by the image sensor corresponding to FIG. FIG. 10 is an explanatory diagram illustrating a method for detecting a length in a conveyance direction of a sheet. FIG. 6 is an explanatory diagram illustrating a method for detecting skew of a sheet. It is a figure which shows the change of the light-and-dark pattern by the image sensor corresponding to FIG. It is a simplified perspective view which shows 2nd Embodiment of the paper conveying apparatus provided with the displacement detection apparatus by this invention. It is a simplified perspective view which shows 3rd Embodiment of the paper conveying apparatus provided with the displacement detection apparatus by this invention. It is the schematic of the conventional light-shielding type optical sensor. It is explanatory drawing which shows the skew detection method using the conventional light-shielding type optical sensor.

Explanation of symbols

1, 2 Transport rollers (transport means)
DESCRIPTION OF SYMBOLS 4 Displacement detection apparatus 5 Drive motor 11 Encoder 41 Displacement detection apparatus 44 Light emission part 45 LED light source 46 Lens 47 Light reception part 48 Image sensor 49 Lens 50 Control apparatus 60 Belt conveyance apparatus (conveyance means)

Claims (10)

A light emitting unit that irradiates light from the LED light source onto the surface of the paper being transported at a predetermined position on the paper transport path, and light reflected from the paper surface within a certain detection region irradiated with the light is received and brightened. A light receiving unit having an image sensor that reads a pattern and converts it into an electrical signal; and a control device that is connected to the light receiving unit and receives the electrical signal of the light and dark pattern, and the image sensor is periodically A displacement detection device for conveyance paper configured to read a light and dark pattern in the detection area of the paper being conveyed ;
Conveying means for conveying paper;
In a control method of a paper transport device comprising a drive motor for driving the transport means,
The control device is configured to compare the positions of common portions of a plurality of light and dark patterns periodically read by the image sensor, and calculate a displacement amount of the paper,
When the sheet is not present in the detection area of the displacement detector by the control device, the rotation speed of the drive motor is maintained at a constant value as the first feedback control, and the sheet is present in the detection area. In some cases, as the second feedback control, the movement speed of the conveyance surface of the conveyance means becomes the target speed based on the movement speed of the sheet calculated from the displacement amount in the sheet conveyance direction detected by the displacement detection device. And a method for controlling the sheet conveying device, wherein the rotational speed of the drive motor is controlled . In the control method of the paper conveyance device according to claim 1,
The second feedback control is driven so that the moving speed of the conveying surface of the conveying means becomes a value substantially corresponding to the moving speed of the paper calculated from the displacement amount in the paper conveying direction detected by the displacement detecting device. A method for controlling a sheet conveying apparatus , which controls a rotation speed of a motor . In the control method of the paper conveying apparatus according to claim 1 or 2 ,
After the transition from the state where no paper is present in the detection area of the displacement detection device to the state where the paper is present, the control device detects the movement speed of the conveyance surface of the conveyance means and the displacement detection device for a predetermined time. The first feedback control is continued when the difference between the movement speed of the conveyance surface of the conveyance means and the sheet movement speed is greater than a predetermined value, and when the difference is less than the predetermined value. And a control method for the sheet conveying device, wherein the control is switched to the second feedback control. In the control method of the paper conveyance device according to any one of claims 1 to 3 ,
The displacement detection device is disposed on the transport unit so as to be able to read a light / dark pattern on the transport surface of the transport unit,
The conveyance means is idled by a predetermined displacement amount, the displacement detection device detects the displacement amount of the conveyance surface of the conveyance means, and compares the detected displacement amount with the predetermined displacement amount of the conveyance surface of the conveyance means, Control of a sheet conveying apparatus, wherein when a detection error occurs between the detected displacement amount and the predetermined displacement amount, the detected displacement amount is corrected to the same value as the predetermined displacement amount. Method. In the control method of the paper conveyance device according to any one of claims 1 to 4 ,
A method for controlling a sheet conveying apparatus, wherein the conveying means is a conveying roller. In the control method of the paper conveyance device according to any one of claims 1 to 4 ,
The method of controlling a sheet conveying apparatus, wherein the conveying means is a conveying belt wound around a plurality of rollers. In the control method of the paper conveying apparatus according to claim 5 ,
With a mark indicating a reference position of one rotation of the transport roller,
Detecting the amount of displacement in the circumferential direction of the mark by the displacement detection device by rotating the transport roller once;
The detected displacement is compared with the true full circumference of the transport roller obtained by calculation, and when a detection error occurs between the detected displacement and the true full circumference, the detected displacement Is corrected to the same value as the true perimeter, a method for controlling a sheet conveying apparatus. In the control method of the paper conveyance device according to claim 6 ,
A mark indicating a reference position of one cycle of the conveyor belt is attached to the conveyor belt,
Rotate the conveyor belt to detect the displacement amount of the mark by the displacement detection device,
The detected displacement amount is compared with the true total length of the transport belt obtained by calculation. When a detection error occurs between the detected displacement amount and the true total length, the detected displacement amount is A method for controlling a sheet conveying device, wherein the sheet is corrected to the same value as the total length. In the control method of the paper conveyance device according to any one of claims 1 to 3 ,
The light / dark pattern of the paper is read by the reading device, and is stored in the storage unit of the control device as an original light / dark pattern,
While reading the light / dark pattern of the paper being conveyed by the displacement detector, the read light / dark pattern is compared with the original light / dark pattern,
A control method for a paper transport device that detects a paper abnormality by recognizing that the light and dark patterns are out of a predetermined range of identity. In the control method of the paper conveyance device according to any one of claims 1 to 3 ,
Read the light and dark patterns of the sequentially conveyed paper by the displacement detector,
Compare the light and dark pattern read from any paper with the light and dark pattern of the paper read before the paper,
A control method for a sheet conveying apparatus, wherein the abnormality of the sheet is detected by recognizing that both the light and dark patterns are out of a predetermined range of identity.

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