JP2019118054A - Document feeder - Google Patents

Abstract

To provide a technique enabling detection of a mounting angle of an imaging element used for detecting a transport state of a document in a document feeder capable of transporting the document.SOLUTION: A document feeder includes: a document table on which a document is placed; a transport path along which the document placed on the document table is transported; an imaging element disposed at a position capable of imaging the document transported from the document table and performing photoelectric conversion by receiving light reflected by an imaging target; a detection unit that detects a moving direction of the imaging target on the basis of the image acquired by the imaging element; and an opposing member that is disposed at a position facing the imaging element and has an opposing surface capable of performing imaging by the imaging element, and in which the opposing surface is movable relative to the imaging element. The attachment angle of the imaging element with respect to the transport direction of the document on the transport path is detected on the basis of the movement direction of the opposing surface detected by the detection unit.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a technique for detecting the transport state of a document in a document transport apparatus capable of transporting a document.

  Conventionally, there has been proposed a technique for detecting the amount of movement of a document in the conveyance direction for the purpose of detecting whether or not the document has been conveyed normally in the document conveyance device (Japanese Patent Application Laid-Open No. 2001-147118). In Patent Document 1, the conveyance direction from the optical sensor using an encoder that detects the movement amount of the document in the conveyance direction and an optical sensor that measures the displacement amount in a specific first detection direction that is not orthogonal to the conveyance direction. The amount of skewing is determined from the amount of displacement to the first direction and the amounts of displacement in the first and second detection directions. Further, the amount of displacement in the transport direction is determined using this amount of skewing and the amount of displacement from the encoder.

JP, 2013-209196, A

  As described above, in the technique of detecting the document transport direction using an optical image sensor (optical sensor), when there is a deviation in the mounting angle of the image sensor with respect to the document transport direction, the detection accuracy of the document transport direction Decreases. Such a shift in the mounting angle of the imaging device is often caused by a mounting error at the time of mounting the imaging device. In addition, the factor of the deviation of the mounting angle is the vibration applied to the device by opening / closing the unit attached with the imaging device or opening / closing another unit, expansion / contraction of material due to aging or temperature change, and the user touching the imaging device. There is a change in the mounting angle etc.

  The present invention has been made in view of the above problems. An object of the present invention is to provide a technique capable of detecting a deviation of a mounting angle of an imaging device used for detecting a conveyance state of a document in a document conveyance device capable of conveying a document.

  The document conveying apparatus according to an aspect of the present invention can pick up an original document on which a document is placed, a conveyance path on which the document placed on the document table is conveyed, and a document conveyed from the document table An imaging element disposed at a proper position and receiving light reflected by the imaging object to perform photoelectric conversion, and a detection unit detecting a moving direction of the imaging object based on an image acquired by the imaging element; An opposing member disposed at a position facing the imaging device and having an opposing surface that can be imaged by the imaging device, wherein the opposing surface is configured to be movable relative to the imaging device. And a mounting angle of the image pickup element with respect to the conveyance direction of the document on the conveyance path is detected based on the movement direction of the facing surface detected by the detection unit.

  According to the present invention, in the document conveyance device capable of conveying a document, it is possible to detect the deviation of the attachment angle of the imaging device used for detecting the conveyance state of the document. As a result, it is possible to correct the mounting angle of the imaging element and to detect the transport state of the document with higher accuracy.

FIG. 1 is a cross-sectional view schematically showing the configuration of a document conveyance device according to a first embodiment. FIG. 2 is a schematic view schematically showing the configuration of main parts of the document conveyance device of FIG. 1; FIG. 1 is a partial cross-sectional view schematically showing the arrangement of an optical sensor according to a first embodiment. The schematic diagram which shows the structure of an optical sensor roughly. FIG. 6 is a top view showing an arrangement example of an optical sensor, a pickup roller, a separation roller, and an image reading sensor. Sectional drawing which shows the example of arrangement | positioning of the case body which covers an optical sensor and its periphery. The schematic diagram which shows roughly the image which performed signal processing to the image obtained from the optical sensor. The schematic diagram which shows the characteristic of the moving speed of imaging object, and the detection accuracy of an optical sensor. The schematic diagram which shows the overlap of the imaging object which moved. The schematic diagram which shows the characteristic of the detection accuracy of an optical sensor with respect to the overlap degree of an imaging region. FIG. 7 is a cross-sectional view schematically showing the configuration of a document conveyance device according to a second embodiment. FIG. 12 is a schematic view schematically showing the configuration of main parts of the document conveyance device of FIG. 11; The fragmentary sectional view which shows roughly the example of arrangement | positioning of the optical sensor which concerns on 3rd Embodiment. The conceptual diagram which shows the moving direction and moving speed of an opposing surface member. The conceptual diagram which shows the movement direction and movement speed of an opposing surface member, and the attachment angle shift of an optical sensor. The schematic diagram which shows roughly the structural example of an optical sensor and an opposing surface member. The schematic diagram which shows roughly the structural example of an optical sensor and an opposing surface member. FIG. 13 is a schematic view schematically showing the configuration of main parts of a document conveyance device according to a fifth embodiment. The figure which shows the example of the movement direction of an opposing surface member, and the attachment angle shift of an optical sensor. The figure which shows the example of coordinate transformation for correction | amendment of the attachment angle shift of an optical sensor. The schematic diagram which shows schematically the structural example of the optical sensor which concerns on 5th Embodiment, and an opposing surface member. FIG. 17 is a schematic view schematically showing the configuration of main parts of a document conveyance device according to a seventh embodiment. The schematic diagram which shows schematically the structural example of the optical sensor which concerns on 7th Embodiment, and an opposing surface member.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the present invention according to the claims, and all combinations of the features described in the embodiments are not necessarily essential to the solution means of the present invention. .

First Embodiment
First, a document conveyance device according to a first embodiment of the present invention will be described.

<Document Transfer Device 200>
FIG. 1 is a partial cross-sectional view schematically showing the configuration of a document conveyance device (image reading device) according to the first embodiment, and FIG. 2 schematically shows the configuration of the main part of the document conveyance device of FIG. It is a schematic diagram shown to.

  In FIG. 1 and FIG. 2, the document conveying device 200 includes a sheet taking device 101. A plurality of sheets are loaded (placed) on a sheet loading table (original table) 1, and the sheet loading table 1 is configured to be movable up and down. The loading table drive motor 2 raises and lowers the sheet loading table 1. The sheet detection sensor 3 detects that the sheet stacked on the sheet stacking table 1 is at the sheet loading position. The sheet stacking detection sensor 12 detects that sheets are stacked on the sheet stacking surface 1 a of the sheet stacking table 1.

  A pick-up roller 4 (pick-up means) as an example of a document pick-up unit feeds sheets from the sheet stacking table 1 from the sheet stacking table 1. The pickup roller drive motor 5 rotates the pickup roller 4. In FIG. 2, the upper surface of the sheet is at the sheet take-in position, and when the pickup roller 4 is rotated, sheet take-in starts. Further, the pickup roller 4 can be moved to a sheet taking-in position and a retracted position above the sheet taking-in position by a driving means (not shown). The pickup roller 4 moves to the taking-in position when taking in a sheet, and to the retracted position when taking-in is finished.

  A feed roller 6 as an example of a document pickup unit is provided on the downstream side of the pickup roller 4 and is driven by the feed motor 8 so as to rotate the sheet in the transport direction downstream side. ing. The separation roller 7 provided opposite to the feed roller 6 with the conveyance path interposed therebetween is a separation motor 9 via a torque limiter (slip clutch) (not shown) that rotates in a direction to push the sheet back in the conveyance direction. I am always receiving from When one sheet is present between the feeding roller 6 and the separating roller 7, the feeding roller is determined according to the upper limit value of the rotational force in the direction in which the separating roller 7 pushes the sheet upstream. The rotational force in the direction in which the sheet is fed downstream is increased by the frictional force between the sheet fed downstream by 6 and the separation roller 7, and the separation roller 7 rotates following the feeding roller 6. (Turn around).

  On the other hand, when there are a plurality of sheets between the feeding roller 6 and the separating roller 7, the separating roller 7 receives rotation from the roller shaft in a direction to push the sheet back to the upstream side. Do not transport to the side.

  Thus, the sheet is overlapped by the action of feeding the sheet of the feeding roller 6 to the downstream side and the action of preventing the sheet of the separating roller 7 to be conveyed to the downstream side, and the feeding roller 6 and the separating roller 7 When the sheet is sent to the nip portion, only the uppermost sheet is fed to the downstream side, and the other sheets are not conveyed to the downstream side, so that the overlapped sheets are separated and fed. Thus, the feed roller 6 and the separation roller 7 constitute a pair of separation rollers 42. The separation roller pair 42 functions as an example of an original separation unit for separating and conveying a plurality of originals to be conveyed one by one. In the present embodiment, the separation roller pair 42 is used, but instead of the separation roller pair 42, a separation belt roller pair in which one of the separation roller and the feeding roller is a belt may be used. . Further, the separation roller may be replaced with a separation pad, and by contacting the sheet, the conveyance of a plurality of sheets to the downstream side may be prevented.

  Further, by providing the double feed detection sensor 30 at a position where the separated document passes, it is possible to detect whether the document can be separated one by one by the document separation unit. In the present embodiment, a detection device using an ultrasonic wave transmitter / receiver as the double feed detection sensor 30 is used, and double feed can be detected by the attenuation amount of the ultrasonic wave between the transmitter and receiver across the transport path.

  The conveyance motor 10 conveys the sheet after document separation to the image reading position where the image reading sensor 14 (image reading unit) reads an image of the document, and further conveys the sheet to the discharge position. Drive the (document conveyance unit). Further, the conveyance motor 10 drives each roller so that the conveyance speed of the sheet can be changed in accordance with the setting such as the optimum speed for reading the sheet and the resolution of the sheet.

  The nip adjustment motor 11 adjusts a gap between the feed roller 6 and the separation roller 7 or a pressing force with which the feed roller 6 is in pressure contact with the separation roller 7 via a sheet. As a result, the gap or the pressing force adapted to the thickness of the sheet is adjusted, and the sheet can be separated.

  The registration clutch 19 transmits the rotational driving force of the conveyance motor 10 to the registration roller 18 (original conveyance unit) or cuts off the transmission. By stopping the rotation of the registration roller pair constituted by the registration rollers 17 and 18, the leading end of the fed sheet is abutted against the nip portion of the registration roller pair, and the skew feeding of the sheet is corrected.

  The transport roller pair configured by the transport rollers 20 and 21, the transport roller pair configured by the transport rollers 22 and 23, and the roller pair further downstream shown in FIG. 1 transport the sheet to the discharge stacking unit 44. The two guide plates of the upper guide plate 40 and the lower guide plate 41 guide the sheet conveyed by the separation roller pair, the registration roller pair, each conveyance roller pair, and the downstream roller pair.

  The pre-registration sensor 32 is disposed on the upstream side of a pair of registration rollers formed by the registration rollers 17 and 18 and detects a sheet to be conveyed. The post-registration sensor 33 is disposed downstream of the pair of registration rollers formed by the registration rollers 17 and 18 and detects a sheet to be conveyed.

  The document conveying device 200 includes a control unit 45 that controls the operation of the entire device. The control unit 45 is configured of, for example, one or more processors (CPUs).

  The document conveying apparatus 200 according to the present embodiment includes an optical sensor 111 which is a sensor for detecting the behavior of the document to be conveyed, and an opposing surface member (an opposing member) 301 disposed at a position facing the optical sensor 111. Have. In the present embodiment, as shown in FIGS. 1 and 2, the optical sensor 111 is disposed at a position facing the sheet loading table 1, and the facing surface member 301 is a sheet loading that is the facing surface of the optical sensor 111. It is arranged in the platform 1.

  The opposite surface member 301 is movable by being driven by the motor 302, and is used to detect the attachment angle (attachment state) of the optical sensor 111 in the document conveyance device 200. The control unit 45 can control the movement of the facing member 301 by controlling the motor 302. As described later, while the document is not interposed between the optical sensor 111 and the opposing surface member 301, the control unit 45 moves the opposing surface member 301 relative to the optical sensor 111 to The amount of movement or the direction of movement of the surface of the facing member 301 facing the optical sensor 111 is detected by the sensor 111. Further, the control unit 45 detects the mounting angle of the optical sensor 111 with respect to the transport direction of the document on the transport path, based on the detection result of the movement amount or the movement direction of the facing surface member by the optical sensor 111.

<Optical sensor 111>
Next, with reference also to FIGS. 3 and 4, the optical sensor 111 according to the present embodiment will be described. The optical sensor 111 is a sensor for detecting the behavior of the document being conveyed, and is used to detect the amount of movement or the movement direction of the object to be imaged (the document or the opposing surface member 301) in the present embodiment. For example, the optical sensor 111 is used to detect the amount of movement of the document in the transport direction and the amount of movement in the direction orthogonal to the transport direction. The optical sensor 111 is disposed upstream of the image reading sensors 14 and 15 in the sheet (original) conveyance direction. Thus, detection of the document transport direction can be started earlier. That is, when a change in the behavior of the document occurs, it is possible to detect the movement earlier by using the optical sensor 111.

  As shown in FIG. 3, the substrate 100 on which the optical sensor 111 is mounted is mounted in parallel to the sheet stacking table 1 at a position facing the sheet stacking table 1. That is, the substrate 100 is attached such that the imaging surface of the optical sensor 111 is parallel to the surface (opposing surface) of the sheet loading table 1. Here, an area image sensor is used as the optical sensor 111. In the case of this embodiment, the fact that the imaging surface of the optical sensor 111 is parallel to the surface of the sheet loading table 1 means that the substrate 100 on which the optical sensor 111 is mounted is parallel to the surface of the sheet loading table 1 It is synonymous with

  Here, an example is shown in which the imaging surface of the optical sensor 111 is parallel to the surface of the sheet loading table 1, but the imaging surface of the optical sensor 111 does not have to be always parallel to the surface of the sheet loading table 1 It may be done. That is, as long as the imaging surface of the optical sensor 111 can detect the behavior of the document to be conveyed, the optical sensor 111 may be attached to the upstream side or the downstream side of the conveyance path.

  In the present embodiment, using the optical sensor 111 as an image pickup element, an image of a document to be conveyed is obtained, and the movement amount of the document is detected based on the image information to detect the behavior of the document. The optical sensor 111 is disposed so as to be separated by a predetermined distance D from the imaging reference surface in the transport path in which the document is transported. The imaging reference surface is a surface facing the optical sensor 111 which is an imaging element and serving as a reference for imaging by the optical sensor 111. In the present embodiment, a transport path (a document (sheet) which is an imaging object is transported The surface of the sheet loading table 1) is determined as an imaging reference surface. However, in a situation where a plurality of originals are stacked (placed) on the sheet loading table 1, a position corresponding to the surface of the original to be conveyed is the imaging reference plane. That is, the surface of the sheet stacking table 1 at the uppermost position in the raising and lowering range of the sheet stacking table 1 when feeding the document substantially coincides with the imaging reference surface.

  By separating the optical sensor 111 from the imaging reference surface by a predetermined distance D, it is possible to obtain an image of the original at an appropriate interval regardless of the type of the original and the position where the optical sensor 111 is disposed. Therefore, as the optical sensor 111, it is preferable to use a sensor whose imaging focus matches the document at a predetermined distance D apart. In the present embodiment, the optical sensor 111 is disposed apart from the imaging reference plane as the predetermined distance D by about 20 mm to 30 mm.

  In the present embodiment, the movement amount of the document is obtained by acquiring the images of the document at predetermined time intervals by the optical sensor 111 and comparing the images at predetermined time intervals (or the images based on the predetermined movement amount intervals). Determine The determination of the movement amount of the document is performed, for example, by an IC provided on the substrate 100 on which the optical sensor 111 is mounted. In this case, an IC mounted on the substrate 100 functions as a movement amount detection unit. However, the image acquired by the optical sensor 111 may be transmitted to the external device, and the movement amount may be determined on the external device. In that case, it can be said that the movement amount detection unit includes the external device. In that case, the document conveyance device 200 according to the present embodiment is configured to include the portion where the movement amount in the external device is determined. The determination of the movement amount of the document may be performed inside the optical sensor 111 as described later with reference to FIG.

  Detection (determination) of the movement amount or movement direction of the object to be imaged (original or opposing surface member 301) is obtained by acquiring an area image by the optical sensor 111 and A / D (analog / digital) converting the area image. This is done by sequentially comparing the received images. In this embodiment, the case where the optical sensor 111 is a sensor capable of detecting the amount of movement or the direction of movement of the object to be imaged (the detection of the amount of movement or the direction of movement is performed inside the optical sensor 111) will be described. In this case, the optical sensor 111 includes a movement amount detection unit capable of detecting the movement amount or movement direction of the imaging target.

  In the present embodiment, an image sensor (imaging element) is driven by TG (Timing Generator) inside the optical sensor 111 to acquire an image signal, and A / D conversion and analysis of the image signal are performed to move the imaging target. A configuration is employed to detect the amount or direction of movement. Specifically, as shown in FIG. 4B, the optical sensor 111 includes an image sensor, a TG, an AFE (Analog Front End), and a DSP (Digital Signal Processor) (so-called system on). Chip (SoC)). The optical sensor 111 acquires an area image (image signal) of an imaging target by the image sensor driven by the TG, and performs A / D conversion on the acquired image signal by the AFE. Furthermore, the optical sensor 111 detects the movement amount of the imaging target based on the digital image signal after A / D conversion by the DSP. That is, the DSP functions as a movement amount detection unit.

  As another example, the optical sensor 111 only acquires an image signal, and an image signal processing device (for example, an IC provided on the substrate 100 as described above) outside the optical sensor 111 performs A / D conversion. And the structure which analyzes the image signal, and detects the moving amount | distance or moving direction of an imaging target object may be employ | adopted.

  In the present embodiment, acquisition of an image signal by the optical sensor 111 is performed by irradiating light from the light source unit (light emitting element) to an imaging object (such as a document) and receiving the reflected light by the light receiving unit (image sensor). It is done by converting. The light source unit included in the optical sensor 111 is configured by a laser or a light emitting diode (LED). That is, the optical sensor 111 irradiates infrared imaging object light to the imaging target object by laser, or irradiates light to the imaging target object using light emission by LED, and receives reflected light by the imaging target object, A surface image of an imaging object is acquired.

  In particular, it is preferable to use a laser method for the light source unit, because the movement amount of the document can be detected in more detail. When the laser method is used, it is possible to reduce the decrease in the detection accuracy of the movement amount due to the flapping of the document being conveyed by appropriately selecting the wavelength of the laser light. For example, when the distance D from the document conveyance surface to the optical sensor 111 is about 20 mm for an original document conveyed in a conveyance path having a height of about 2 mm, use infrared laser light having a wavelength of about 850 nm. Thus, it has been experimentally proved that the detection accuracy of the movement amount can be maintained even if the document being conveyed is fluttered.

  Here, with reference to FIG. 5 and FIG. 6, the arrangement method of the optical sensor 111 will be described more specifically. FIG. 5 is a diagram in which the optical sensor 111, the pickup roller 4 and the separation roller 7 are extracted when the document conveyance device is viewed in a form facing the sheet feeding surface. In the present embodiment, a member holding the pickup roller 4 extends and holds the optical sensor 111. 6 is a cross-sectional view taken along the line AA 'of the structure of FIG. 5, and shows an example in which the optical sensor 111 is covered by the case body 112. As shown in FIG. In order to maximize the detection area of the optical sensor 111, it is desirable that the optical sensor 111 be disposed in a direction in which the pickup roller 4 is not imaged so that only the document is imaged (in a part of the imaging area). However, if there is an area other than the original, the amount of information for detecting the amount of movement or the direction of movement decreases, which causes a decrease in detection accuracy).

  However, among the wall surfaces of the case body 112 covering the periphery of the optical sensor 111, the direction in which the optical sensor 111 is disposed in the direction in which the wall surface having the shorter distance to the sheet feeding surface is disposed upstream When the optical sensor 111 is disposed in the direction in which the wall surface of the case body 112 having a shorter distance to the sheet feeding surface is disposed on the downstream side, the opposite When the detection area can be configured to include only the document, the wall surface having a shorter distance to the paper feed surface is disposed downstream in consideration of generation of paper dust in the pickup roller 4 and the separation roller 7 It is preferable to arrange the optical sensor 111 in the direction. By arranging in this manner, it is possible to reduce the adhesion of paper dust to the surface facing the optical sensor 111 (the light transmitting plate 112 c in FIG. 13 described later).

  When continuously conveying a bundle of documents stacked on the sheet stacking table 1 to a document feeding port provided upstream of a conveyance path, the document is conveyed by providing an optical sensor 111 at a position where a plurality of documents can pass simultaneously. The trailing edge of the document can be imaged to detect the trailing edge. In the present embodiment, as detection of the trailing edge of the document, it is possible to utilize variation in output when the trailing edge of the preceding document forms a shadow on the next document.

  A specific arrangement of the optical sensor 111 is slightly upstream of the leading end of the sheet loading table 1 at which the document (sheet) is loaded. That is, it is a position facing the sheet stacking table 1 at the leading edge side of the sheet stacking table 1. Further, by disposing the optical sensor 111 lower than the height of the sheet feeding unit having the pickup roller 4 and the feeding roller 6, the enlargement of the apparatus main body can be suppressed.

  As shown in FIGS. 1 and 2, the sheet stacking table 1 is provided with movable restriction members 51 at both ends in the width direction with respect to the transport direction, and restricts the width direction of the document (sheet). doing. By moving the regulating member 51 in the width direction to match the width of the document to be conveyed, it is possible to prevent the document from being skewed during conveyance. In the present embodiment, the optical sensor 111 may be attached to the regulating member 51 or may be attached to the exterior of the main body.

  As shown in FIG. 4A, when an optical member (a lens 103 in this example) such as a prism or a lens (not shown) is disposed in front of the optical sensor 111, the optical sensor The optical member is disposed such that the amount of light received by the light 111 is maximized. If there is no problem in operation, these optical members can be omitted in favor of miniaturization and cost.

  FIG. 7 shows a schematic view of an image obtained by performing signal processing on an image obtained from the optical sensor 111. In FIG. 7, a point extracted as a feature point is represented by a black square in the image captured at a certain time (t = 0). Here, as an example, 1 mass = 1 pixel (that is, the number of pixels of the optical sensor 111 is 5 × 5 = 25 mass), but one mass is represented after representing an average value of a plurality of pixels or a specific calculation. You may form. As an example, bright or dark points are extracted as feature points as compared to other squares. As a feature point, it is possible to extract asperities and scratches on the surface of the document. From this state, when time t 'has elapsed, the optical sensor 111 acquires an image again, extracts a black square (feature point), and shows how the black square (feature point) moves. By comparison, the movement amount from time 0 to t ′ is acquired (calculated). In the example of FIG. 5, it is determined that one space has moved to the right and one space has moved upward. As described above, the movement amount may be acquired by the DSP inside the optical sensor 111, or may be performed by an image signal processing device provided separately from the optical sensor 111.

  Here, as described above, the optical sensor 111 is disposed such that the imaging surface (light receiving surface) of the optical sensor 111 and the surface of the document are parallel to each other. The optical sensor used in the present embodiment has the characteristics as shown in FIG. As shown in FIG. 8A, the optical sensor is generally optical when the light receiving surface of the optical sensor and the surface of the document are parallel to each other (the left side of FIG. 8B). Compared with the case where the light receiving surface of the sensor is inclined with respect to the surface of the document (right side in FIG. 8B), it has a characteristic that it can follow up to a region where the moving speed of the document to be imaged is higher.

<Details of Arrangement of Optical Sensor 111>
Next, the arrangement of the optical sensor 111 will be described in detail using FIG. 3 again.

  Regarding the distance D between the optical sensor 111 and the sheet stacking table 1, in the imaging area of the optical sensor 111, the imaging range in the transport direction is L, the image acquisition interval time of the sensor is T, and the maximum value of the transport speed of the document transport unit The distance D is adjusted to be a distance satisfying LTT × V, where V is a distance. In the following description, L may be expressed as an imaging region. Note that the imaging area indicates the view angle of the optical sensor 111 in the imaging reference plane of the optical sensor 111, and if there is an imaging target (original) in the imaging reference plane, acquire an image in the imaging area. Can. Here, the conveyance direction is not the direction in which the original (sheet) is actually conveyed, but the direction in which the apparatus is intended to convey, that is, the direction along the rotation direction of the feed roller and the conveyance roller Vertical direction). Although the image acquisition interval time of the sensor is T, in fact, the movement amount detection unit for detecting the movement amount of the sheet based on the image acquired by the optical sensor 111 is provided, and the movement in the movement amount detection unit The acquisition interval of the quantity should be T. That is, while acquiring the image acquisition interval time of the sensor at an interval shorter than T, detection of the movement amount in the movement amount detection unit is performed at T intervals, and other acquired data is ignored or the movement amount detection unit Alternatively, the input may not be performed. Although the following description will be made based on the image acquisition interval time T of the sensor for the sake of explanation, this is the same as the explanation here, and may be replaced with the movement amount acquisition interval time T.

  Here, when the angle of view (viewing angle) of the combination of the optical sensor 111 and the optical member becomes large, the area which can be imaged at one time becomes large, so L has a large value. In addition, since the optical sensor 111 has a certain viewing angle, L can have a large value also by increasing the distance D.

  The image acquisition interval time T has a small value if the time required for the optical sensor 111 to acquire an image is short. Specifically, if the image reading clock of the optical sensor 111 is fast, the time for the optical sensor 111 to read the image signal becomes short. Alternatively, the smaller the number of pixels of the optical sensor 111, the shorter the time for reading out the image signal. However, when the number of pixels is small, the value of L may be influenced (small).

  When it is necessary to average a plurality of images obtained from the optical sensor 111 in order to detect the amount of movement of the document as described above, it takes time until the detection. In this case, it is necessary to replace the image acquisition interval time T with the movement amount detection interval time T ′ and adjust the distance D between the optical sensor 111 and the sheet stacking table 1 so as to satisfy L ≧ T ′ × V.

  However, since L ≧ T × V (or L ≧ T ′ × V) is the minimum condition, a more optimal arrangement will be mentioned here. For example, in the case of using the 5 × 5 pixel optical sensor shown in FIG. 7, while the optical sensor captures an image once, accurate detection is possible if the document has a displacement of 1 pixel or less. It becomes. That is, it is sufficient to satisfy L ≧ T × V × 5. From this relational expression, L / 5T is obtained as the upper limit value Vmax of the document transport speed for accurate detection.

  Assuming that the operation at the upper limit value Vmax is difficult, another embodiment will be described using FIGS. 9 and 10. FIG. 9 schematically shows the overlapping degree (overlap rate) of the imaging region of the document at a certain time t1 and another time t2 (> t1). As the overlapping area in both images in the area captured by the optical sensor 111 is larger at time t1 and time t2, the number of feature points described above can be detected and tracked more, so the movement amount Can be detected more accurately. In this case, the optical sensor 111 is disposed to satisfy αL ≧ T × V using αL (α indicates the degree of overlap of the imaging regions in FIG. 9 and α <1), and the transport speed V is set. That is, αL / T is obtained as the upper limit value Vmax of the document transport speed from this relational expression.

  As shown in FIG. 10, the detection accuracy of the optical sensor exhibits a characteristic that increases as the degree of overlap of the imaging regions is increased. When the detection accuracy is saturated at a predetermined overlap degree α1 of the imaging regions as a detection algorithm, Vmax may be set so that the overlap degree of the imaging regions is α1.

  As an example, in order to set the detection accuracy of the movement amount to a certain degree, it is preferable that the overlapping area αL be N or more as an imaging pixel. In this case, assuming that the number of pixels in the transport direction is L as an optical sensor, αL may be overlapped as pixels in the transport direction. In this case, L−V × T ≧ N (= αL). Therefore, in this case, by setting the transport speed so as to satisfy V ≦ (L−N) / T, the moving amount can be detected accurately. As a specific example, in the case of using the optical sensor shown in FIG. 7 and assuming that the overlapping area is 4 pixels or more (α = 4/5 = 0.8), V ≦ (5-4) The transport speed V may be set so that / T = 1 / T.

  In the present embodiment, as shown in FIG. 10, although the detection accuracy slightly increases from around where the overlapping degree is α1 = 0.8, the movement amount detection itself is performed at every image acquisition interval time. It is not always necessary to succeed in continuous detection. By setting the transport speed to such an extent that the amount of movement can be detected, that is, the extent to which the overlapping degree is α1 as the first threshold, the throughput of transport can be improved. In the present embodiment, when α = α1 = 0.6 (overlapping rate 60%), detection is possible well and the load on the processing unit can be suppressed, in which case N = Since αL = 0.6 × 5 = 3.0, V ≦ 2 / T.

  The above is an example, and although the characteristic of detection accuracy differs depending on the optical sensor to be used, it is preferable to set the overlapping degree α1 of the imaging area such that the detection accuracy starts to saturate or slightly saturates In the embodiment, α = 0.6, but it does not matter.

  As the transport speed V is the speed at which the document transport device transports the document, the speed increases stepwise (or steplessly depending on the type of motor) from the start of document transport until the predetermined speed is reached. It will be done. Conversely, when the document conveyance is stopped, the speed also decreases stepwise (or steplessly) from the predetermined speed toward the stop state (V = 0).

  As the setting value of the conveyance speed V described above, the speed V1 at the time when the conveyance speed reaches a predetermined speed after the start of document conveyance satisfies the above-mentioned relational expression so that the speed at the rising or falling Is slower than V1, the detection accuracy of the optical sensor does not decrease, and the amount of movement can be suitably detected.

  Here, for example, if there is no space in the apparatus, it is conceivable to dispose an optical member having a large angle of view in front of the optical sensor 111 to enlarge the imaging region L in the transport direction. With this configuration, it is possible to cope with a larger transport speed V.

  Alternatively, the image acquisition interval time T of the optical sensor 111 may be changed in conjunction with the change of the conveyance speed V. The above-mentioned TG controls the image acquisition interval time T so that the imaging overlap area is always constant even if the conveyance speed V changes, by determining the imaging overlap area (αL) as a target. By performing this control, even if the transport speed V changes, the detection accuracy of the optical sensor is always constant.

  Similarly, in the present embodiment, instead of setting the transport speed V as described above, the image acquisition interval time T may be adjusted to adjust the overlap degree α of the imaging regions to a predetermined value. Good. Although the detection accuracy of the optical sensor can be efficiently improved by setting the overlap degree α to α1, the present invention is not limited to this, as long as the image acquisition interval time T can maintain a certain degree of overlap α. Good.

  The output of the optical sensor may be output to an IC or the like that processes the output at a predetermined image acquisition interval time T, but another example will be shown below.

  For example, in the case of using an optical sensor that outputs a movement amount when the detection amount of the movement amount in the optical sensor exceeds a predetermined value, a case where conveyance of 150 sheets / minute is performed as conveyance of an A4 document will be described. Even if the document interval distance is taken into consideration, the transport speed V is around 1000 mm / sec. In this case, as an example of the image acquisition interval time T, if the resolution of the optical sensor is set to output 1500 cpi, that is, 1500 counts per inch, movement of 1/1500 inch per count, ie, about 0.017 mm is possible. If there is, it will output one count. For the transport speed V = 1000 mm / sec, 1000 / 0.017100060000 counts per second, that is, 1 count is output at 1/60000 sec.

  As shown in FIG. 8A, the optical sensor has a characteristic that the performance of the set resolution can not be exhibited when the transport speed is higher than a predetermined transport speed (detection accuracy decreases). On the other hand, the conveyance speed V = 1000 mm / sec actually used by setting the resolution to about 1500 cpi so that equivalent detection accuracy can be exhibited with respect to the conveyance speed that can be set as the document conveyance device. For moderate conditions, the detection accuracy can be kept constant without lowering the resolution. In particular, as described with reference to FIG. 8B, the performance of the resolution set by arranging so that the surface of the document and the imaging surface of the optical sensor are parallel to each other (the left side of FIG. 8B) The performance of the set resolution can be maintained even if the transport speed is increased, and the detection accuracy of the optical sensor can be maintained.

  In addition, some optical sensors have resolution of 5000 cpi or more, and if resolution is increased, detection accuracy of the optical sensor is improved, but it is necessary to operate the optical sensor at high speed, and the operation inside the optical sensor Since the clock frequency is increased, the load and power consumption on an IC or the like that processes the output of the optical sensor also increase. Considering detecting the document conveyance state as shown here, by setting the resolution to about 1500 cpi, sufficient detection accuracy is required for the conveyance speed V of about 100 sheets / minute required as the conveyance speed. It is possible to secure the load on the processing and the like.

  According to the configuration of the document conveyance device 200 as described above, since the conveyance condition of the document can be detected by one optical sensor 111, the device can be provided without increasing the size and cost of the device. Further, in the present embodiment, as shown in FIG. 4A, the light source unit 102 is provided for the purpose of increasing the amount of light received by the optical sensor 111. In the present embodiment, the light source unit 102 is provided as a device separate from the optical sensor 111, but the optical sensor 111 and the light source unit 102 may be configured as one device.

<Facing member 301>
Next, detection of the mounting angle (mounting state) of the optical sensor 111 using the facing surface member 301 will be described. As shown in FIGS. 1 and 2, in the document conveying device 200, an opposing surface member 301 is disposed on the sheet stacking table 1 which is the opposing surface of the optical sensor 111. The facing surface member 301 can be driven by the motor 302 to move relative to the optical sensor 111. More specifically, the opposing surface member 301 is driven by the motor 302 when the mounting angle correction of the optical sensor 111 attached to the document conveyance device 200 is performed, and is relative to the optical sensor 111. And move at a predetermined speed in a predetermined (predetermined) direction. In the present embodiment, the control unit 45 controls the facing surface member 301 so as to move at a predetermined speed in a predetermined direction relative to the optical sensor 111 (image sensor).

  The optical sensor 111 captures an image of the facing surface member with the image sensor while the facing surface member 301 moves, and detects the amount of movement or the moving direction of the facing surface member. The control unit 45 detects the mounting angle of the optical sensor 111 with respect to the document transport direction based on the detection result of the movement amount or the movement direction of the facing surface member 301 output from the optical sensor 111. Specifically, the moving direction of the opposite surface member 301 is set as the document conveyance direction, and the movement direction of the opposite surface member 301 detected by the optical sensor 111 is corrected so as to coincide with the conveyance direction of the optical sensor 111. In other words, the moving direction of the facing member 301 is considered to be the document transport direction.

  The control unit 45 can detect, for example, the deviation of the mounting angle of the optical sensor 111 from the mounting angle (reference angle) which is a reference. The control unit 45 moves (for example, rotationally moves) the optical sensor 111 so that the mounting angle of the optical sensor 111 is corrected based on the detected mounting angle. That is, the control unit 45 corrects the mounting angle of the optical sensor 111 so as to eliminate (or reduce) the deviation of the detected mounting angle. For example, the control unit 45 executes the mounting angle correction by rotating the optical sensor 111 by driving the optical sensor 111 with a motor (not shown) for correcting the mounting angle. The control unit 45 executes such mounting angle correction at appropriate timing.

  In the present embodiment, the facing surface member 301 is disposed on the sheet loading table 1 which is the facing surface of the optical sensor 111, but when the facing surface of the optical sensor 111 is the lower guide plate 41, the lower guide plate 41 is used. It may be arranged. That is, the facing surface member 301 may be disposed on a member present at a position facing the optical sensor 111. Further, the shape of the facing surface member 301 is not limited, and the facing surface member 301 may be an outer peripheral portion of a roller-like member as shown in FIG. 1 or may be a flat plate-like member. The opposite surface member 301 may or may not contribute to the conveyance of the document at the time of document conveyance, and there is no restriction on the operation at the time of document conveyance. For example, the facing surface member 301 may move relative to the optical sensor 111 even when the document is conveyed. If the document is not on the sheet loading table 1, the position and drive at which the movement can be detected by the optical sensor 111 may be performed.

<Execution timing of mounting angle correction>
In the document conveying apparatus 200 in which the optical sensor 111 is attached at a position facing the sheet loading table 1 as in the present embodiment, when a document (sheet) exists in the sheet loading table 1, the optical sensor 111 faces the facing member 301 can not be imaged. For this reason, the control unit 45 needs to execute the mounting angle correction at the timing when the document is not loaded (placed) on the sheet loading table 1.

  In order to execute the mounting angle correction at such timing, the document conveyance device 200 (control unit 45) may have a dedicated calibration mode for executing the mounting angle correction according to a predetermined condition. For example, as such a calibration mode, an operation unit (not shown) of the document conveyance device 200 is used while no document exists on the sheet loading table 1 (the sheet loading detection sensor 12 does not detect the sheet). The mounting angle correction may be performed according to the instruction of the user who performed the process. Further, the mounting angle correction may be performed in response to the opening and closing of the case of the document conveyance device 200.

  Further, when a plurality of documents stacked on the sheet stacking table 1 are continuously transported, the mounting angle correction may be performed in response to the last document being transported to the transport path. Specifically, the sheet detection sensor 3 detects that the last document of the plurality of documents has been lost from the sheet take-in position, and the passage of the rear end of the document is detected by the pre-registration sensor 32. Depending on the situation, attachment angle correction may be performed. That is, when it is detected that the rear end of the last original sheet of the plurality of original sheets stacked on the sheet loading table 1 has passed through the original separation portion (separation roller pair 42), the mounting angle correction is performed. It may be done. Furthermore, the sheet stacking detection sensor 12 may be combined, that is, in a situation where the sheet detection sensor 3 does not detect a sheet, and the sheet stacking detection sensor 12 does not detect a sheet. It may be determined that the sheet has not been stacked, and the mounting angle correction of the optical sensor 111 may be performed using the period during which the sheet conveyed last is being conveyed.

  As described above, in the present embodiment, the document conveying apparatus 200 includes the sheet loading table 1 on which the document is loaded, a transport path by which the document loaded on the sheet loading table 1 is transported, and the sheet loading table And an optical sensor 111 disposed at a position where an image of a document conveyed from 1 can be captured. The optical sensor 111 has a DSP that detects the movement amount or movement direction of the imaging target based on the image acquired by the image sensor. Note that the detection of the movement amount or movement direction of the imaging target may be performed by an IC provided on the substrate 100, for example. The document conveyance device 200 further includes an opposing surface member 301 disposed at a position facing the optical sensor 111 and having an opposing surface that can be imaged by the optical sensor 111. The facing surface member 301 (the facing surface of the facing surface member) is configured to be movable relative to the optical sensor 111. In the document conveyance device 200, the attachment angle of the optical sensor 111 with respect to the conveyance direction of the document in the conveyance path is detected by the control unit 45 based on the detection result of the movement amount or movement direction of the facing surface member 301 by the optical sensor 111. .

  According to the present embodiment, in the document conveying device 200 capable of conveying a document, it is possible to detect a deviation of the attachment angle of the optical sensor 111 (image sensor) used for detecting the conveyance state of the document. Further, when the mounting angle correction of the optical sensor 111 is performed based on the detection result of the mounting angle, it is possible to detect the transport state of the document with higher accuracy using the optical sensor 111.

Second Embodiment
Next, a document conveyance device according to the second embodiment will be described. The description of the parts common to the first embodiment will be omitted.

<Document Transfer Device 400>
FIG. 11 is a partial cross-sectional view schematically showing the configuration of a document conveyance device (image reading device) according to the first embodiment, and FIG. 12 schematically shows the main part of the document conveyance device of FIG. It is a schematic diagram shown to.

  As shown in FIG. 11, the document conveying device 400 is roughly divided into a sheet loading table 1, an upper unit 401, and a lower unit 402. The document conveyance device 400 basically has the same configuration as the document conveyance device 200 (FIGS. 1 and 2) of the first embodiment. However, the document conveyance device 400 is different from the document conveyance device 200 in that the optical sensor 111 is disposed downstream of the separation roller pair 42 in the conveyance direction of the sheet (document), among others. The differences from the first embodiment will be mainly described below.

  In the document conveyance device 400 of the present embodiment, as shown in FIG. 11, the sheet stacking surface 1 a of the sheet stacking table 1 and the conveyance path are provided to be inclined with respect to the installation surface of the document conveyance device 400. . The sheets stacked on the sheet stacking table 1 are separated one by one by a separation roller pair 42 provided on the downstream side of the sheet stacking table 1 in the sheet conveyance direction and configured by the feeding roller 6 and the separation roller 7. Into the transport path. In the document conveyance device 200 according to the first embodiment, a plurality of sheets stacked on the sheet stacking table 1 are sequentially taken into the conveyance path from the sheet placed thereon. On the other hand, in the document conveyance device 400 of the present embodiment, a plurality of sheets stacked on the sheet stacking table 1 are sequentially taken into the conveyance path from the sheet placed below.

  As shown in FIG. 12, the substrate 100 on which the optical sensor 111 is mounted is attached in parallel with the sheet conveyance direction in the conveyance path. The optical sensor 111 is disposed downstream of the separation roller pair 42 so as to detect the movement amount or movement direction of the sheet conveyed on the conveyance path. In the document conveyance device 400 of the present embodiment, by using the optical sensor 111, it is possible to detect the conveyance condition of the document, as in the first embodiment.

  The document conveyance device 400 includes an opposing surface member 301 disposed in the conveyance path at a position facing the optical sensor 111. Although the optical sensor 111 and the substrate 100 are disposed in the upper unit 401, an opening is provided at a position facing the optical sensor 111 in the upper unit 401 so that the opposing surface member 301 can be seen from the optical sensor 111. There is.

  In the present embodiment, the facing surface of the facing surface member 301 that faces the optical sensor 111 constitutes a portion of the lower unit 402 that faces the conveyance path. The opposing surface member 301 is configured by a member different from the member (for example, a sheet metal) forming the conveyance path in the lower unit 402. Similar to the first embodiment, the facing surface member 301 can be driven relative to the optical sensor 111 by being driven by the motor 302, and is used to correct the mounting angle of the optical sensor 111. .

<Execution timing of mounting angle correction>
In the configurations shown in FIGS. 11 and 12, not only at the timing when the sheet (original) is not loaded on the sheet loading stand 1, but also when the sheets are loaded on the sheet loading stand 1 within the imaging area of the optical sensor 111. If a document does not exist, imaging of the facing surface member 301 by the optical sensor 111 is possible. That is, in the state where the sheet is not conveyed in the area facing the optical sensor 111 on the conveyance path, the imaging of the facing surface member 301 by the optical sensor 111 is possible.

  For example, the control unit 45 corrects the mounting angle at a timing when reading (scanning) of the document stacked on the sheet stacking table 1 is started (before the first document is taken into the conveyance path by the separation roller pair 42). It may be executed. Before the first original is taken into the conveyance path by the separation roller pair 42, no original exists in the area facing the optical sensor 111, and the optical sensor 111 can pick up the image of the facing surface member 301. Specifically, the document reading instruction is issued from an operation unit provided in the image reading apparatus or an information processing apparatus connected to the image reading apparatus, and the mounting angle correction is performed before the separation roller pair 42 is driven. Just do it.

  When performing attachment angle correction, the control unit 45 moves the facing surface member 301 relative to the optical sensor 111, and causes the optical sensor 111 to detect the moving amount or the moving direction of the facing surface member 301. The control unit 45 detects the mounting angle of the optical sensor 111 with respect to the document transport direction based on the detection result of the movement amount or the movement direction of the facing surface member 301 output from the optical sensor 111.

  Further, the control unit 45 detects that the passage of the rear end of the document conveyed from the sheet loading table 1 is detected by the pre-registration sensor 32 (that is, the rear end of the document deviates from the imaging region of the optical sensor 111). Accordingly, mounting angle correction may be performed. For example, when a plurality of documents stacked on the sheet loading table 1 are continuously conveyed, the control unit 45 causes the rear edge of the document being conveyed to pass immediately after the position of the pre-registration sensor 32 ( That is, the mounting angle correction is executed).

  The detection of the rear end of the sheet (original) to be conveyed can be performed not by the pre-registration sensor 32 but by the optical sensor 111. When the document deviates from the imaging region of the optical sensor 111 (that is, passes through the end of the imaging region), the movement amount of the document detected by the optical sensor 111 changes. Depending on the setting of the optical sensor 111, this change causes a change in the movement amount of the document due to the shadow of the sheet being imaged by the optical sensor 111 and the document fluttering at the rear end and the floating being generated. It is due to. Such change in movement amount can be used to detect the trailing edge of the sheet. That is, as one example, the timing at which a specific change occurs in the movement amount in the direction orthogonal to the sheet conveyance direction obtained by the optical sensor 111 is taken as the timing when the rear end of the sheet passes the end of the imaging area By specifying, it is possible to detect the trailing edge of the sheet.

  As described above, according to the present embodiment, in the document conveyance device 400 capable of conveying a document, it is possible to detect the deviation of the attachment angle of the optical sensor 111 (image sensor) used for detecting the conveyance state of the document. . Further, when the mounting angle correction of the optical sensor 111 is performed based on the detection result of the mounting angle, it is possible to detect the transport state of the document with higher accuracy using the optical sensor 111.

  According to the configuration of the present embodiment, it is possible to detect the conveyance state of the document by one optical sensor 111 and to detect the conveyance state after the document is restricted. Therefore, the conveyance state of the document can be detected without performing additional processing, and the processing time is not increased. Accordingly, it is possible to provide a device that does not unnecessarily increase the processing time without increasing the size and cost of the device.

Third Embodiment
Next, a document conveyance device according to the third embodiment will be described. The description of the parts common to the first and second embodiments will be omitted.

  FIG. 13 is a partial cross-sectional view schematically showing an arrangement example of the optical sensor 111 in the document conveyance device according to the present embodiment, showing a configuration example of the optical sensor 111 whose periphery is covered with a mold member and a light transmission plate. ing. The configuration of the optical sensor 111 shown in FIG. 13 is applicable to any of the document feeder 200 (FIGS. 1 and 2) and the document feeder 400 (FIGS. 11 and 12).

  In the example of FIG. 13, the optical sensor 111 is mounted on the substrate 100 and, for example, a light emitting element (laser light source) that outputs infrared laser light and a light receiving element that receives reflected light of light output from the light emitting element And a sensor element including The light emitting element and the light receiving element are disposed adjacent to each other on the optical sensor 111. The mold members 112 a and 112 b and the light transmitting plate 112 c shown in FIG. 13 constitute a part of the case body 112 covering the periphery of the optical sensor 111. The mold members 112 a and 112 b form a wall perpendicular to the substrate 100. The light transmitting plate 112 c is connected to an end of the mold members 112 a and 112 b opposite to the end of the substrate 100 side. In the arrangement of FIG. 13, the wall formed by the mold member 112b is longer than the wall formed by the mold member 112a such that the light transmitting plate 112c has an inclination with respect to the surface of the substrate 100 or the above-described imaging reference surface. ing.

  The light transmitting plate 112 c transmits light that is output from the light emitting element of the optical sensor 111 and travels to the document. The light transmitted through the light transmitting plate 112 c and reflected by the document is transmitted through the light transmitting plate 112 c and received by the light receiving element of the optical sensor 111. With such a configuration of the optical sensor 111, paper dust can be prevented from directly adhering to the optical sensor 111, and paper dust can be prevented from being erroneously extracted as a feature point. The light emitted by the optical sensor 111 (light emitting element) preferably uses light in the near infrared region of about 850 nm, and a filter capable of transmitting light in that band may be used as the light transmitting plate 112c. preferable.

  As shown in FIG. 13, an optical sensor 111 is disposed in the middle of the conveyance path 1300 at a position between the conveyance roller 1301 and the conveyance roller 1302. Here, the conveyance roller 1301 may be the feeding roller 6 or the separation roller 7. In these cases, FIG. 13 is a schematic view for showing the positional relationship, and it is assumed that the optical sensor 111 is actually smaller than the transport roller 1301.

  13A, of the walls (mold members) 112a and 112b constituting the case body 112, the long wall 112b is disposed on the upstream side in the sheet conveying direction, and the short wall 112a is in the sheet conveying direction. It is located downstream. This arrangement is effective to suppress the influence of external light directed from the outside to the inside of the case body 112. Note that, as shown in FIG. 13B, the short wall 112a may be disposed on the upstream side in the sheet conveyance direction, and the long wall 112b may be disposed on the downstream side in the sheet conveyance direction. This arrangement is, for example, the paper dust generated by the conveyance roller 1302 when the rotation number of the conveyance roller 1302 arranged downstream of the conveyance roller 1301 is high (that is, when paper dust tends to fly by the conveyance roller 1302). It is effective to reduce the influence of

  According to the present embodiment, it is possible to prevent the detection accuracy of the transport state of the document by the optical sensor 111 from being degraded due to the influence of paper dust generated by the transport roller when transporting the sheet (document).

Fourth Embodiment
Next, a document conveyance device according to the fourth embodiment will be described. In the fourth embodiment, a specific example of the mounting angle correction of the optical sensor 111 will be described.

  The document conveyance device according to the present embodiment may be the document conveyance device 200 of the first embodiment or the document conveyance device 400 of the second embodiment. Hereinafter, the mounting angle correction of the optical sensor 111 will be described by using the document conveyance device 200 of the first embodiment as an example. The differences from the first to third embodiments will be mainly described below.

  The document conveying apparatus 200 has the configuration shown in FIGS. 1 and 2 as in the first embodiment. The opposite surface member 301 moves up and down in accordance with the movement of the sheet loading table 1. In a state in which the document is not loaded on the sheet loading table 1, the control unit 45 raises the sheet loading table 1 so that the facing surface member 301 is positioned in the imaging area of the optical sensor 111. In this position, the facing member 301 repeats movement at a predetermined speed in a predetermined direction under the control of the control unit 45.

  FIG. 14 is a conceptual view showing the moving direction and moving speed of the facing member 301. As shown in FIG. As long as the detection by the optical sensor 111 is possible within the imaging area of the optical sensor 111, the movement direction and the movement speed of the facing surface member 301 are not limited. For example, as shown in FIG. 14 (a), the opposite surface member 301 may move at a moving speed V1 in the document transport direction, and as shown in FIG. 14 (b), a direction orthogonal to the transport direction. To move at a moving speed V2. Further, as shown in FIG. 14C, the facing surface member 301 may move at a moving speed V3 in the direction of an arbitrary angle θ1 with respect to the document conveyance direction.

  As described in the first embodiment, the opposing surface member 301 is driven by the motor 302 when the mounting angle correction of the optical sensor 111 is performed, and is relative to the optical sensor 111, and Move at the default speed in the default direction. Meanwhile, the optical sensor 111 detects the movement amount or movement direction of the imaging target (the facing surface member 301) by the DSP based on the image acquired by the image sensor (imaging element).

  As described above, the moving direction of the opposite surface member 301 is predetermined in the document conveyance direction (that is, the relative movement direction is predetermined in the document conveyance direction). For this reason, it is possible to obtain the mounting angle of the optical sensor 111 with respect to the document conveyance direction from the movement direction of the facing surface member 301 detected by the optical sensor 111 (movement amount detection unit).

  For example, as shown in FIG. 15A, the facing surface member 301 moves at a moving speed V3 in the direction of the angle θ1 with respect to the document conveyance direction. As shown in FIG. 15B, the movement direction of the facing member 301 detected by the optical sensor 111 is an angle with respect to the axis that should coincide with the document conveyance direction when there is no deviation of the mounting angle of the optical sensor 111. Suppose that it is in the direction of Φ1. In this case, the mounting angle deviation of the optical sensor 111 with respect to the document conveyance direction is (θ1−φ1).

  The control unit 45 drives the optical sensor 111 by a motor (not shown) for mounting angle correction so as to rotate the optical sensor 111 so that the mounting angle deviation (θ1−Φ1) described above is corrected. Thus, the mounting angle correction of the optical sensor 111 can be realized.

  The mounting angle correction may be performed repeatedly. That is, after completion of the execution of one mounting angle correction, the mounting angle correction may be performed again. As a result, it is possible to increase the correction accuracy of the mounting angle of the optical sensor 111. In addition, when the mounting angle correction is repeatedly performed, the moving direction and the moving speed of the facing surface member 301 may be different from those in the previous execution. As the moving speed of the facing surface member 301 is slower, the detection accuracy of the moving speed of the facing surface member 301 by the optical sensor 111 is higher. Therefore, for example, the mounting angle of the optical sensor 111 is corrected more effectively by executing the mounting angle correction in a state where the facing surface member 301 is moved at a moving speed slower than the moving speed at the previous execution time. It will be possible.

  The opposite surface member 301 may not be in contact with the document at the time of document conveyance. For example, as shown in FIG. 16A, the facing surface member 301 may be disposed via an optically transparent member that abuts on the document to be conveyed. In addition, the moving direction of the facing member 301 may be the conveyance direction of the document as shown in FIG. 16 (a), or perpendicular to the conveyance direction of the document as shown in FIG. 16 (b). It may be orthogonal to That is, as described above, as long as the detection by the optical sensor 111 is possible within the imaging area of the optical sensor 111, the movement direction of the facing surface member 301 is not limited.

  In this embodiment, the movement amount or movement direction of the facing member 301 is detected using the optical sensor 111 used to detect the conveyance state of the document, and the optical sensor 111 in the conveyance direction of the document is detected based on the detection result. Correct the mounting angle of. This makes it possible to increase the detection accuracy of the transport state of the document using the optical sensor 111 when transporting the document.

Fifth Embodiment
Next, a document conveyance device according to the fifth embodiment will be described. In the fifth embodiment, another example regarding detection of the attachment angle of the optical sensor 111 will be described. The differences from the first to fourth embodiments will be mainly described below.

  FIG. 18 is a cross-sectional view schematically showing the configuration of the main part of the document conveyance device according to the present embodiment. FIG. 17A is a schematic view schematically showing the configuration around the optical sensor 111. As shown in FIG. The document conveyance device 200 of the present embodiment has basically the same configuration as that of the first embodiment. However, the position at which the optical sensor 111 is disposed is different. In the present embodiment, the optical sensor 111 is disposed near the feed roller 6 as shown in FIGS. 18 and 17A. Further, the outer peripheral surface of the separation roller 7 is used as the facing surface member 301. Since the separation roller 7 is driven by the separation motor 9, in the present embodiment, the motor 302 for driving the facing member 301 is not provided.

  Detection of the movement amount or movement direction of the facing surface member 301 (that is, the outer peripheral surface of the separation roller 7) by the optical sensor 111 for correction of the attachment angle of the optical sensor 111 is performed at timing when the document does not exist in the conveyance path. . When the control unit 45 executes the mounting angle correction of the optical sensor 111, the outer peripheral surface (the facing surface member 301) of the separation roller 7 as the imaging object is rotated by the optical sensor 111 while rotating the separation roller 7 at a predetermined speed. To detect the movement amount or movement direction of The control unit 45 performs attachment angle correction (rotational movement of the optical sensor 111) of the optical sensor 111 based on the detection result of the optical sensor 111 as in the above-described embodiment. The rotation direction of the separation roller 7 corresponding to the facing surface member 301 when performing the mounting angle correction may be clockwise or counterclockwise in FIG.

  In this embodiment, as shown in FIG. 17A, the optical sensor 111 is disposed in the vicinity of the feeding roller 6, and the separation roller 7 is used as the facing surface member 301, so that The configuration in which the diameter of the separation roller 7 is larger is employed. In general, in order to facilitate conveyance of a sheet (original) by the feed roller 6, a configuration in which the diameter of the feed roller 6 is larger than that of the separation roller 7 is often employed. However, as in the present embodiment, it is also possible to adopt a configuration in which the diameter of the separation roller 7 is larger than that of the feed roller 6. In this configuration, when the sheet is not in the conveyance path, the separation roller 7 is brought along with the feeding roller 6. Assuming that no slippage occurs between the two rollers, the separation roller 7 rotates at the same circumferential speed as the feed roller 6. In fact, it is assumed that almost no slippage occurs between the feed roller 6 and the separation roller 7 because they contact with the nip pressure to a certain extent.

  Next, the mounting angle correction of the optical sensor 111 will be further described. Here, as shown in FIG. 19A, an orthogonal coordinate system defined by the x axis and the y axis is used, with the document transport direction as the x axis. Further, as an orthogonal coordinate system from which the output of the optical sensor 111 can be obtained, as shown in FIG. 19B, an orthogonal coordinate system defined by the x ′ axis and the y ′ axis is used. The angular deviation between the x-axis and the x'-axis is θ2. θ2 corresponds to the mounting angle deviation of the optical sensor 111 with respect to the document conveyance direction.

In the state where the facing member 301 (in the present embodiment, the separation roller 7) is moving in the direction of the predetermined angle φ2 with respect to the x-axis, (x ′, y Suppose that ') = (a, b) is obtained. In this case, assuming that the angle of the moving direction of the separation roller 7 with respect to the x ′ axis is θ3, θ3 can be obtained by the following equation.
θ3 = arctan (b / a)
Further, the angular deviation θ2 between the x-axis and the x'-axis is determined by
θ2 = φ2-θ3

  Thus, based on the detection result (x ′, y ′) = (a, b) of the movement amount of the facing surface member 301 acquired by the optical sensor 111, an optical sensor in the document transport direction (reference direction) It is possible to obtain the deviation θ 2 of the mounting angle of 111. In the present embodiment, the attachment angle deviation θ2 is acquired (calculated) by the control unit 45 of the document conveyance device 200 based on the detection result of the movement amount of the facing surface member 301 acquired by the optical sensor 111. .

By using the mounting angle deviation θ2 obtained as described above, the movement amount data acquired by the optical sensor 111 at the time of document conveyance is determined by the coordinate system defined by the x-axis and y-axis corresponding to the document conveyance direction. (I.e., the movement direction of the document acquired at the time of conveyance of the document is converted to the movement direction based on the conveyance direction of the document). Thus, it is possible to detect the behavior of the document at the time of document transport based on the converted movement amount data. Specifically, as shown in FIG. 20, movement amount data (x ′, y ′) = (a1, b1) acquired by the optical sensor 111 at the time of document conveyance is corrected, and the mounting angle deviation θ2 of the optical sensor 111 is corrected. It can be converted (corrected) into movement amount data of a coordinate system defined by the x axis and the y axis. This coordinate conversion is performed by the following equation.
x component = a1 × cos (θ2) −b1 × sin (θ2)
y component = a1 × sin (θ2) + b1 × cos (θ2)

  Note that instead of performing coordinate conversion of the data each time movement amount data is acquired by the optical sensor 111 during document conveyance, coordinate conversion of data to be compared may be performed based on the attachment angle deviation θ2. Specifically, for example, thresholds of the x component and the y component to be compared with movement amount data acquired by the optical sensor 111 are specified by the x ′ axis and the y ′ axis by coordinate conversion based on the attachment angle deviation θ2. It may be converted to the threshold of the coordinate system to be As a result, when analyzing the movement amount data acquired by the optical sensor 111, it is not necessary to perform coordinate conversion of the movement amount data each time, and the amount of processing required to analyze the movement amount data can be reduced.

  In this embodiment, using the outer peripheral surface of the roller (in this example, the separation roller 7) contributing to the conveyance of the document as the facing surface member 301, detection of (attachment of) the mounting angle of the optical sensor 111 and correction of the mounting angle are performed. ing. As a modified example of such an embodiment, for example, as shown in FIG. 17B, the roller (in this example, the separation roller 7) contributing to the conveyance of the document is power coupled by a power coupling mechanism (not shown). Another roller (rotating member) may be used as the facing surface member 301. The rotating member may be configured to contribute to the transport of the document on the transport path, and is motively coupled to a roller (in this example, the separation roller 7) contributing to the transport of the document only when detecting the mounting angle deviation. May be Further, as shown in FIG. 17C, the rotary member is disposed outside the conveyance path with the transparent member 310 constituting a part of the conveyance path interposed, and does not contribute to conveyance of the document. It is also good. As described above, the facing surface member 301 may or may not contribute to the conveyance of the document at the time of document conveyance, and there is no restriction on the operation at the time of the document conveyance.

  In addition, as a modification of the above-described embodiment, for example, as illustrated in FIG. 21, the rotation shaft of the separation roller 7 or a member connected to the rotation shaft may be used as the facing surface member 301. . FIG. 21 is a schematic view of the separation roller 7, the feed roller 6, and the optical sensor 111 from the upstream side (front side of FIG. 21) to the downstream side (back side of FIG. 21) of the transport path. In FIG. 21, the document is conveyed from the front side to the back side between the upper guide plate 40 and the lower guide plate 41. As shown in FIG. 21A, it is possible to use a rotating shaft that rotates in conjunction with the separation roller 7 as the facing surface member 301. The arrangement shown in FIG. 21A is preferable from the viewpoint of reliably detecting the amount of movement of the document, since the document always passes between the two separation rollers 7 arranged along the direction orthogonal to the transport direction. is there. Further, as shown in FIG. 21B, the outer circumferential surface of a rotating body that rotates in conjunction with the separation roller 7 may be used as the facing surface member 301. In this case, for example, the optical sensor 111 may be disposed on the outside of both of the two separation rollers 7, and a rotating body facing each optical sensor 111 may be used as the facing surface member 301.

  According to the present embodiment, it is possible to use a rotating member such as the separation roller 7 contributing to the conveyance of the document as the facing surface member 301, and repeat the detection and correction of the mounting angle deviation of the optical sensor 111. It will be easier. Although the separation roller 7 is used as the facing surface member 301 in the embodiment described above, the outer peripheral surface of the feeding roller 6 may be used as the facing surface member 301 as well. In this case, the conveyance direction of the document conveyed by the feeding roller 6 can be matched with the movement direction of the facing member 301, which is preferable.

Sixth Embodiment
Next, a document conveyance device according to a sixth embodiment will be described. In the above embodiment, the facing surface member 301 facing the optical sensor 111 is moved relative to the optical sensor 111 in a predetermined direction at a predetermined speed, and based on the detection result of the movement amount or the movement direction Thus, the attachment angle of the optical sensor 111 is detected. On the other hand, in the present embodiment, an example will be described in which the optical sensor 111 itself is also moved for detection of (the deviation of) the attachment angle of the optical sensor 111 and correction thereof. The differences from the first to fifth embodiments will be mainly described below.

  FIG. 17D is a view schematically showing the configuration around the optical sensor 111. As shown in FIG. The optical sensor 111 of the present embodiment is driven by a drive mechanism (not shown), and is configured to be movable to a predetermined speed in a predetermined direction. For example, as shown in FIG. 17D, the controller 45 is controlled to move in the predetermined direction at the velocity V1 (t) to detect the deviation of the attachment angle of the optical sensor 111. On the other hand, the control unit 45 controls the facing surface member 301 facing the optical sensor 111 so as to move in the predetermined direction at the velocity V2 (t). Note that the facing surface member 301 may be a member that moves horizontally with respect to the conveyance road surface as shown in FIG. 17D, or may be a rotatable rotating member (for example, a rotating member as in the above embodiment). , Separation roller 7).

  The moving speeds V1 (t) and V2 (t) described above can be set to arbitrary speeds. For example, the relative velocity of the facing surface member 301 to the optical sensor 111 is V (t) = V2 (t) −V1 (t). Based on this, as in the above-described embodiment, the control unit 45 detects the deviation of the mounting angle of the optical sensor 111. Furthermore, the control unit 45 may correct the mounting angle of the optical sensor 111 as in the above-described embodiment based on the detected deviation of the mounting angle. Further, the control unit 45 may perform coordinate conversion of movement amount data acquired by the optical sensor 111 at the time of document conveyance based on the detected deviation of the attachment angle.

  In the present embodiment, the moving direction of the facing member 301 is not limited to the direction shown in FIG. 17D, and any direction as long as the movement of the facing member 301 can be detected by the optical sensor 111. It is possible to set Further, in FIG. 17 (d), it is assumed that the facing surface member 301 moves (V2 (t) ≠ 0), but the facing surface member 301 is stationary or fixed (V2 (t) = 0). May be

  In the present embodiment, as in the above-described embodiment, the moving direction of the facing member 301 is detected using the optical sensor 111 used to detect the conveyance state of the document, and the conveyance direction of the document is detected based on the detection result. The mounting angle of the optical sensor 111 with respect to is corrected. This makes it possible to increase the detection accuracy of the transport state of the document using the optical sensor 111 when transporting the document.

Seventh Embodiment
Next, a document conveyance device according to a seventh embodiment will be described. In the present embodiment, as a modification of the above-described embodiment, an example will be described in which the reference member 305 corresponding to the facing surface member 301 of the above-described embodiment can be advanced and retracted within the imaging region of the optical sensor 111. The differences from the first to sixth embodiments will be mainly described below.

  FIG. 22 is a cross sectional view schematically showing the configuration of the main part of the document conveyance device according to the present embodiment. FIG. 23A is a diagram schematically showing an example of the configuration and operation of the reference member 305, which corresponds to FIG. In the present embodiment, a reference member 305 as a reference of the mounting angle of the optical sensor 111 and a motor 306 for driving the reference member 305 are provided. The reference member 305 is driven by a motor 306 that operates according to an instruction of the control unit 45. The reference member 305 may be power coupled to another motor by a power coupling mechanism such as a power coupling clutch, instead of the motor 306.

  As shown in FIG. 23A, the reference member 305 is directed to the downstream side in the transport direction in the transport path via the entrance / exit provided on the upstream side of the optical sensor 111 in the transport direction of the upper guide plate 40. , And advances into the imaging region of the optical sensor 111. Thereby, the reference member 305 realizes the same function as the facing surface member 301 in the above-described embodiment.

  The optical sensor 111 is controlled to detect the amount of movement or the direction of movement of the reference member 305 at the timing when the reference member 305 advances to the imaging region of the optical sensor 111 in the transport path. Be done. The control unit 45 detects the deviation of the mounting angle of the optical sensor 111 based on the detection result of the movement amount or the movement direction of the reference member 305 by the optical sensor 111 as in the above-described embodiment. The control unit 45 mounts the optical sensor 111 based on the detection result of the movement amount or movement amount of the reference member 305 when the reference member 305 retracts out of the conveyance path, not when advancing into the conveyance path. An angle deviation may be detected. Further, the detection of the deviation of the mounting angle of the optical sensor 111 and the correction of the mounting angle may be performed both when the reference member 305 advances into the conveyance path and when retreating from the conveyance path. Thereby, it is possible to improve the correction accuracy of the mounting angle.

  The reference member 305 may be a sheet-like member or a block-like member as shown in FIG. 23 (a). The material and the shape of the reference member 305 are not limited as long as the optical sensor 111 is made of a member capable of extracting a feature point when imaging the reference member 305.

  Further, as a modification of the example of FIG. 23 (a), the reference member 305 is configured to advance into the conveyance path from the lower guide plate 41 constituting the lower surface of the conveyance path, as shown in FIG. 23 (b) It is also good. Further, as shown in FIG. 23C, the reference member 305 may be configured to advance from the side surface of the conveyance path into the conveyance path. Further, in the present embodiment, as shown in FIG. 23A, the reference member 305 is advanced into the conveyance path from the upstream side to the downstream side in the conveyance direction. However, the reference member 305 has the conveyance direction It may be configured to advance into the transport path from the downstream side to the upstream side. In this manner, the reference member 305 can advance into the conveyance path and be retracted out of the conveyance path, and can be positioned within the imaging region of the optical sensor 111 when advancing into the conveyance path. It suffices to have a possible configuration.

  Note that, as a modification of the present embodiment, a document capable of advancing into the conveyance path and retracting out of the conveyance path may be used instead of the reference member 305 (the facing surface member 301). The original may be any medium that can be conveyed by the original conveying device 200, and may not be a medium exclusively used for detection and correction of the mounting angle of the optical sensor 111. In this case, also at the time of execution of the mounting angle correction of the optical sensor 111, the original corresponding to the reference member 305 is advanced into the conveyance path and retracted from the conveyance path by conveying the original as in normal document conveyance. A configuration may be used. As long as the movement amount or the movement direction can be detected by the optical sensor 111, the conveyance speed and the conveyance direction of the document as the reference member 305 are not limited. In this case, the transport direction and transport speed of the document may be known in advance, or may be detected by the image reading sensors 14 and 15 each time. When the document reading direction and the feeding speed are detected by the image reading sensors 14 and 15, the same document may be read by the image reading sensors 14 and 15 and the optical sensor 111 at the same timing. Further, the document reading speed and direction are obtained by the image reading sensors 14 and 15, the moving amount and moving direction of the document are obtained by the optical sensor 111, and the mounting angle of the optical sensor 111 is detected. It is possible to improve the detection accuracy of the angular deviation.

  In this embodiment, the movement amount or movement direction of the reference member 305 corresponding to the facing surface member 301 is detected using the optical sensor 111 used to detect the conveyance state of the document, and the document is detected based on the detection result. The mounting angle of the optical sensor 111 with respect to the transport direction is corrected. This makes it possible to increase the detection accuracy of the transport state of the document using the optical sensor 111 when transporting the document.

  As mentioned above, although the document conveying apparatus of the present invention has been described in detail, the present invention is not limited to the above embodiment, and various improvements and changes can be made without departing from the scope of the present invention. Also, one or more of the above-described first to seventh embodiments can be implemented in combination as appropriate.

  Further, for example, as described in the fifth embodiment and the like as the facing surface member 301, when using a member such as a roller that presses the sheet conveyed in the conveyance path toward the conveyance path, the movement amount of the sheet by the optical sensor 111 When detecting the sheet, it is possible to suppress the fluttering of the conveyed sheet, and to detect the movement amount of the sheet with high accuracy. In this case, it is preferable to provide a transparent member or the like at a position facing the facing surface member 301 so as to hold the sheet therebetween, and to perform detection by the optical sensor 111 at that position. Further, as the facing surface member 301, the sheet may be held by the elasticity of the member itself forming the outer peripheral surface such as a roller, and the roller forming the facing surface member 301 is biased to the optical sensor 111 side. It may be movable. The separation roller 7 in the fifth embodiment is float-supported with respect to the feeding roller 6, and has a structure similar to the structure described here. Actually, a nip is not formed at the position of the separation roller 7 facing the optical sensor 111, but a nip is formed between the feeding roller 6 and the separation roller 7 in the vicinity thereof, so that the sheet is deformed. It can be suppressed to some extent.

1: sheet stacking platform, 1a: sheet stacking surface, 2: stacking platform drive motor, 3: sheet detection sensor, 4: pickup roller, 5: pickup roller drive motor, 6: feeding roller, 7: separation roller, 8: Feeding motor, 9: separation motor, 10: conveyance motor, 11: nip gap adjusting motor, 12: sheet stacking detection sensor, 14, 15: image reading sensor, 17, 18: registration roller, 19: registration clutch, 20 to 20 23: transport roller 30: double feed detection sensor 32: pre-registration sensor 33: post-registration sensor 40: upper guide plate 41: lower guide plate 42: separation roller pair (original separation portion) 44: discharge stacking Unit 45: Control unit 100: Substrate 101: Sheet take-in device 102: Light source 111: Optical sensor 112: Case body 301: Opposite surface member 30 , 306: Motor 305: reference member, 310: transparent member

Claims (20)

A platen on which a document is placed;
A transport path through which a document placed on the document table is transported;
An image pickup device disposed at a position capable of picking up an image of a document conveyed from the document table, receiving light reflected by the object to be photographed, and performing photoelectric conversion;
A detection unit that detects the moving direction of the imaging target based on the image acquired by the imaging element;
An opposing member disposed at a position facing the imaging device and having an opposing surface that can be imaged by the imaging device, wherein the opposing surface is configured to be movable relative to the imaging device. And a member,
A document conveying device, wherein an attachment angle of the image pickup element with respect to a conveyance direction of the document in the conveyance path is detected based on the movement direction of the facing surface detected by the detection unit. The image pickup device further includes a control unit configured to control the facing member so as to move at a predetermined speed in a predetermined direction relative to the image sensor.
The detection unit detects a moving direction of the facing surface based on an image acquired by the imaging device capturing the facing surface being moved.
The document conveyance device according to claim 1, wherein the control unit detects the attachment angle of the image pickup element based on a movement direction of the facing surface detected by the detection unit.   The document conveyance device according to claim 1, wherein the opposite surface is configured to be movable along the conveyance direction.   The said opposing member is a roller provided in the said conveyance path, and is a roller which contact | abuts to the said document and conveys the said document, The said opposing surface is an outer peripheral surface of the said roller, Document feeder. The image forming apparatus further comprises a roller provided in the transport path and configured to transport the original while contacting the original.
The document conveying device according to claim 3, wherein the facing member is a rotating member rotatable in conjunction with the roller, and the facing surface is an outer circumferential surface of the rotating member. The image forming apparatus further comprises a roller provided in the transport path and configured to transport the original while contacting the original.
The document conveying device according to claim 3, wherein the opposing member is a rotating shaft that rotates in conjunction with the roller, and the opposing surface is an outer peripheral surface of the rotating shaft. The image forming apparatus further comprises a roller provided in the transport path and configured to transport the original while contacting the original.
The facing member is a rotating body connected to the rotating shaft of the roller, which rotates in conjunction with the roller, and the facing surface is an outer circumferential surface of the rotating body. The document conveying device according to 3.   The document transport device according to any one of claims 1 to 7, wherein the imaging device is configured to be movable relative to the facing surface when imaging the facing surface. .   9. The document conveying apparatus according to claim 8, wherein when the image pickup device picks up the image of the facing surface, both the facing surface and the image pickup device move.   The document conveying device according to claim 1, wherein the facing member is a member configured to advance to an imaging area where the imaging device can pick up an image and to retract from the imaging area.   3. The document conveying apparatus according to claim 2, wherein the control unit rotationally moves the image pickup element based on a detection result of the attachment angle so that the attachment angle of the image pickup element is corrected. The document processing apparatus further includes a document separating unit for separating and transporting a plurality of documents to be transported one by one.
The document conveyance device according to claim 11, wherein the image pickup element and the opposing member are disposed upstream of the document separation unit in the conveyance direction.   13. The document conveying apparatus according to claim 12, wherein the control unit has a calibration mode for performing the mounting angle correction of the image pickup element at a timing when the document is not placed on the document table.   The control unit executes the mounting angle correction of the image pickup element when it is detected that the rear end of the last document of the plurality of documents placed on the document table has passed through the document separation unit. The document feeder according to claim 12 or 13, characterized in that The document processing apparatus further includes a document separating unit for separating and transporting a plurality of documents to be transported one by one.
The document conveyance device according to claim 11, wherein the image pickup element and the opposing member are disposed downstream of the document separation unit in the conveyance direction.   16. The document conveying apparatus according to claim 15, wherein the control unit executes attachment angle correction of the imaging device when instructed to start conveyance of a document placed on the document table. It further comprises a sensor provided on the downstream side of the image pickup device in the conveyance path for detecting an original to be conveyed;
17. The document conveying apparatus according to claim 15, wherein the control unit executes attachment angle correction of the image pickup element when the rear end of the document to be conveyed is detected by the sensor.   The control unit further converts the movement direction detected by the detection unit for the document having the document conveyed from the document table into the movement direction based on the conveyance direction based on the detection result of the attachment angle. 3. The document feeder according to claim 2, wherein:   The control unit is data of a coordinate system further defined by an axis along the transport direction and an axis along a direction orthogonal to the transport direction, and the detection unit detects the movement direction of the document. 3. The document conveying device according to claim 2, wherein coordinate conversion to a coordinate system corresponding to the detection result of the attachment angle is performed on data to be compared with the result.   20. The document according to any one of claims 1 to 19, further comprising an image reading unit provided downstream of the imaging device in the conveyance direction on the conveyance path and reading an image of the document. Transport device.