JP2019119534A - Position detection mechanism and paper feeder - Google Patents

Abstract

To provide a position detection mechanism and paper feeder capable of accurately detecting a to-be-detected member in a non-contact way moving depending on a thickness, size, etc. of a sheet.SOLUTION: A position detection mechanism 37, for detecting a position of a to-be-detected member (follower roller) 27, comprises a coil spring 34 that expands and contracts with a movement of the follower roller 27 and an induction-type proximity sensor that detects an extension/contraction state of the coil spring 34. A thickness of a sheet S is determined by detecting a position of the follower roller 27 based on an extension/contraction state of the coil spring 34 in a detection area E of the induction-type proximity sensor.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a position detection mechanism and a sheet feeding device for specifying the position of a moving detected member.

  2. Description of the Related Art Conventionally, a sheet feeding device capable of stacking and feeding a large amount of sheets (sheets) of various sizes has been used for an image forming apparatus such as a copying machine or a printer. Such a sheet feeding apparatus includes a storage capable of storing a large amount of sheets, a loading tray capable of moving up and down in the storage, and a sheet feeding mechanism for conveying sheets stacked on the loading tray toward the image forming apparatus. Is equipped.

  The sheet feeding mechanism includes a feeding roller that contacts the uppermost sheet of the plurality of sheets stacked on the stacking tray, a separation roller and a sheet feeding roller that separates the sheet fed by the feeding roller, and the separation roller and The image forming apparatus further includes a conveyance roller pair for conveying the sheet having passed through the sheet supply roller toward the image forming apparatus.

  The transport roller pair is constituted by a drive roller and a driven roller, and the driven roller is elastically pressed into contact with the drive roller. Then, when the drive roller is driven to nip the sheet with the driven roller, the driven roller is elastically oscillated in accordance with the thickness of the sheet (Japanese Patent Application Laid-Open No. 2001-147118).

  As a means for detecting the thickness of the sheet nipped by the pair of conveying rollers, there is provided a position detection mechanism of another mechanism for mechanically detecting the vertical movement of the pair of conveying rollers when the sheet is nipped 2), a configuration provided with a position detection mechanism including a displacement sensor disposed in contact with one of the pair of transport rollers (Patent Document 3), and the like are known.

  On the other hand, the loading tray is provided with a regulating plate for regulating the length direction and the width direction of sheets of various sizes. The restricting plate is slidably disposed along the long grooves provided in the stacking tray, and can be aligned in the length direction and the width direction of the plurality of sheets by sliding in accordance with the sheets of various sizes. As such a sheet size detection means, a stacking tray provided with a position detection mechanism in which a plurality of sensors are arranged along the sliding direction of the regulating plate is disclosed (Japanese Patent Application Laid-Open No. 2000-112118).

Japanese Patent Application Laid-Open No. 2006-188292 Japanese Patent Application Laid-Open No. 2002-072772 JP, 2012-166913, A Unexamined-Japanese-Patent No. 2006-103953

  As a means for detecting the thickness of a conventional sheet, as disclosed in Patent Document 2, it is necessary to provide a position detection mechanism separate from the sheet conveyance mechanism, so that the number of components increases, and There was a problem that the device became large. Further, in a position detection mechanism including a contact type displacement sensor as disclosed in Patent Document 3, it is difficult to obtain an accuracy corresponding to the thickness of a sheet, and it is also possible to use a shaft of a conveyance roller or the like. Since the components are arranged in contact with each other, a detection error may occur due to vibration or the like.

  On the other hand, in the sheet size detection means disclosed in Patent Document 4, a plurality of sensors must be arranged in accordance with the sheet position of various sizes, so the number of parts is increased and the stacking tray is formed. There was a problem that the cost at the time of cost was high.

  Therefore, an object of the present invention is to provide a position detection mechanism and a sheet feeding device capable of accurately detecting a member to be detected which moves according to the thickness, size, and the like of a sheet without contact.

  In order to solve the above-mentioned subject, the position detection mechanism of the present invention is provided with a coil spring which expands and contracts with movement of a detected member, and an induction type proximity sensor which detects an expansion and contraction state of a coil spring. The position of the detected member is specified based on the expansion / contraction state of the coil spring detected in

  The first sheet feeding apparatus according to the present invention is disposed downstream of the stacking tray for stacking sheets, the sheet feeding roller for feeding sheets on the stacking tray, and the sheet feeding direction of the sheet feeding roller, and sandwiches the sheets. Supported by the bearing member, the bearing member rotatably supporting the bearing member in the vertical direction, and the bearing member rotatably supporting one of the pair of conveying rollers. A coil spring for urging one of the conveyance rollers toward the other conveyance roller, and a sheet thickness detection means for detecting the thickness of a sheet sandwiched between the pair of conveyance rollers from the position of the one conveyance roller, The sheet thickness detection means includes an inductive proximity sensor disposed in the vicinity of a direction orthogonal to the expansion and contraction direction of the coil spring and detecting a change in shape when the coil spring is expanded and contracted. Thus based on the shape change of the coil spring to be detected to identify the position of one transport roller supported by the bearing member.

  The second sheet feeding apparatus according to the present invention is provided so as to be movable in a stacking tray for stacking sheets, a sheet feeding unit for feeding sheets on the stacking tray, and in a direction away from or in contact with the sheets. The sheet size detection means for detecting the size of the sheet based on the position of the restriction plate, a restriction plate for restricting one end of the sheet, a coil spring urging the restriction plate toward the sheet, and the sheet size The detecting means is disposed in the vicinity of a direction orthogonal to the expansion and contraction direction of the coil spring, and has an inductive proximity sensor for detecting a shape change when the coil spring is expanded and contracted. The shape change of the coil spring detected by the inductive proximity sensor Based on the position of the regulation plate.

  According to the position detection mechanism of the present invention, the inductive proximity sensor detects the expansion / contraction state of the coil spring which expands / contracts with the movement of the detection target member, so that the moved position can be accurately detected without contacting the detection target member. It can be identified.

  According to the first sheet feeding apparatus of the present invention, any one of the pair of conveying rollers sandwiching the sheet is used as a detected member, and the shape change when the coil spring that biases the detected member expands and contracts is induced proximity Since the detection is performed by the sensor, the thickness of the sheet can be accurately detected in real time without contacting the conveyed sheet. As a result, sheet feeding can be performed according to the thickness of the sheet, and conveyance defects and the like can be prevented.

  According to the second sheet feeding apparatus of the present invention, the restriction plate for restricting the sheets stacked on the stacking tray is used as a detection target member, and the shape when the coil spring which biases the detection target member toward the sheet expands and contracts. Since the change is detected by the inductive proximity sensor, the sheet size can be accurately detected without contacting the stacked sheets. As a result, sheet feeding can be performed according to the size of the sheet, and conveyance defects and the like can be prevented.

FIG. 1 is a cross-sectional view showing an entire configuration of an image forming apparatus system provided with a sheet feeding device. FIG. 2 is a block diagram showing a system configuration of a sheet feeding device. It is a schematic sectional drawing which shows the internal structure of a sheet feeding device. FIG. 2 is a perspective view showing an internal structure of a sheet feeding device. It is the front view (a) and side view (b) of a conveyance roller pair. It is a perspective view which shows the structure of the sheet | seat thickness detection means of 1st Embodiment. It is an action view before sheet | seat nip (a) of a sheet | seat thickness detection means of 1st Embodiment, and after sheet | seat nip (b). It is an action view before sheet | seat nip (a) of a coil spring, and after sheet | seat nip (b). It is an action view before sheet nip (a) of a sheet thickness detection means of a 2nd embodiment, and after sheet nip (b). It is a top view of a loading tray provided with sheet size detection means.

  FIG. 1 shows the overall configuration of an image forming apparatus system provided with the sheet feeding device of the present invention. The image forming apparatus system 1 includes an image forming apparatus 2 for printing an image on a sheet, an original reading apparatus 3 for reading an original, an original feeding apparatus 4 for conveying a sheet to a reading unit of the original reading apparatus 2, and a sheet for the image forming apparatus 2. A sheet feeding device 5 is provided, and an accumulating device 6 is connected to a sheet discharge port of the image forming apparatus 2 to accumulate sheets discharged from the image forming apparatus 2.

  The image forming apparatus 2 includes two sheet feeding cassettes 7a and 7b capable of storing about 100 sheets. Then, the sheet is taken out from any one of the two sheet feeding cassettes 7 a and 7 b and the sheet feeding device 5, and the image data transferred from the document reading device 3 is printed on the taken out sheet. Discharge to device 6

  The sheet feeding device 5 includes a storage case 9 capable of storing a large amount of sheets S larger than the sheet feeding cassettes 7 a and 7 b, a stacking tray 11 for stacking a plurality of sheets S in the storage case 9, and the image forming apparatus 2. And a sheet feeding unit 21 that feeds the sheet S to the image forming apparatus 2 one by one according to a sheet feeding command from the sheet feeding unit. Further, as shown in FIG. 2, the sheet feeding device 5 includes a sheet thickness detection unit 31 and a sheet size detection unit 51, and in each of the detection units, a detection target member that moves in contact with the sheet S. The position detection mechanism 37 capable of determining the thickness and the size of the sheet S is provided by specifying the position.

  As shown in FIGS. 3 and 4, the sheet feeding unit 21 contacts the uppermost surface of the sheets S stacked on the stacking tray 11 so as to send the sheet S out. A separation mechanism including separation roller 23 and paper feed roller 24 for separating and feeding, a pair of conveyance rollers 25 for conveying the sheet S separated into one sheet by the separation mechanism to the image forming apparatus 2, and a stacking tray 11; An elevating mechanism 13 for raising and lowering in the storage case 9 is provided.

  The separation roller 23 is provided with a torque limiter (not shown) on its rotation shaft. As a result, when two or more sheets overlap and are nipped at the pressure contact portion between the sheet feeding roller 24 and the separating roller 23, the sheet feeding roller 24 is stopped to block the sheet feeding of the second and subsequent sheets.

  As shown in FIGS. 5 and 6, the conveying roller pair 25 is composed of a driving roller 26 rotationally driven by a conveying motor (not shown) and a driven roller 27 rotating following the driving roller 26. ing. The driving roller 26 is attached to a first shaft 28 connected to the transport motor, and the driven roller 27 is rotatably attached to a second shaft 29 provided opposite to the first shaft 28. The sheet S is fed out in a state of being nipped between the drive roller 26 and the driven roller 27.

  In the sheet feeding device 5, a lower guide plate 30a and an upper guide plate 30b for guiding the conveyance of the sheet S by the conveyance roller pair 25 are provided. In the lower guide plate 30a and the upper guide plate 30b, a plurality of openings 12 are provided in accordance with the position of the conveyance roller pair 25, and the drive roller 26 and the driven roller 27 are in contact via the respective openings 12 .

  The sheet thickness detection means 31 is provided on the upper guide plate 30b, and detects the position of the driven roller 27 as a detected member in order to detect the thickness of the sheet S nipped by the drive roller 26 and the driven roller 27. A position detection mechanism 37 is provided. The position detection mechanism 37 includes a coil spring 34 that expands and contracts with the movement of the driven roller 27 and an inductive proximity sensor (proximity sensor) 35 that detects the expansion state of the coil spring 34. The coil spring 34 detected by the proximity sensor 35 The position of the driven roller 27 is specified based on the expansion and contraction state of The sheet thickness detection means 31 includes a bearing member 32 for axially supporting both ends of the second shaft 29, and a bearing bracket 33 for slidably holding the bearing member 32, and a coil spring disposed in the bearing bracket 33. The bearing member 32 is biased toward the drive roller 26 by the reference numeral 34. One end portion of the coil spring 34 is fixed to the upper portion of the bearing bracket 33, and the other end portion is disposed so as to be expandable and contractable with the movement of the bearing member 32 in the vertical direction. The proximity sensor 35 is disposed on one end side of the coil spring 34 and in the vicinity of the outer periphery of the coil spring 34.

  The bearing member 32 is biased to the upper guide plate 30 b via a coil spring 34. The bearing bracket 33 has a space portion in which the bearing member 32 and the coil spring 34 can be accommodated, and is fixed on the upper guide plate 30 b.

  The proximity sensor 35 is disposed on one end side of the coil spring 34 and in the vicinity of the outer periphery of the coil spring 34 in the direction perpendicular to the expansion and contraction direction of the coil spring 34 via the mounting plate 36. The proximity sensor 35 detects magnetic loss due to overcurrent generated on the surface of the coil spring 34 which fluctuates due to expansion and contraction. In this embodiment, the proximity sensor 35 linearly detects the magnetic loss caused by the change in the winding density in the predetermined region of the coil spring 34, whereby the position of the driven roller 27 is specified, and the thickness of the sheet S conveyed by this is determined. It can be determined. Therefore, a metallic material having conductivity is used for the coil spring 34.

  FIG. 7A shows a cross-sectional configuration of the sheet thickness detection means 31 when the sheet S is nipped before the sheet S is nipped. In contrast to (a), since the sheet S is nipped between the drive roller 26 and the driven roller 27 in (b), the bearing member 32 resists the coil spring 34 due to the thickness of the sheet S. Slide upwards. The proximity sensor 35 sets a predetermined expansion / contraction direction of the coil spring 34 as a detection area E.

  FIGS. 8 (a) and 8 (b) show in the detection area E the shape change associated with the expansion and contraction of the coil spring 34 corresponding to FIGS. 7 (a) and 7 (b). As shown in FIG. 7, in the state (a) where there is no sheet S between the drive roller 26 and the driven roller 27, the coil spring 34 expands and the coil pitch P 1 spreads, so the winding density decreases. As a result, the output of the proximity sensor 35 also becomes low. Then, when the sheet S is nipped between the drive roller 26 and the driven roller 27, the coil spring 34 is compressed by the thickness of the sheet S to narrow the coil pitch P2, so that the winding density becomes high. The output of the sensor 35 also increases. Since the proximity sensor 35 detects the winding density accompanying such a coarse / dense state of the coil pitch, the thickness of the conveyed sheet S can be determined in real time.

  The transportable sheets S are roughly classified into three types of plain paper, thin paper, and thick paper, and by preparing the correspondence table in which the relationship between the respective thicknesses and the coil pitches P1 and P2 of the coil spring 34 is measured in advance The thickness detection operation can be performed efficiently and accurately.

  According to the sheet thickness detection means 31 described above, sheet feeding and sheet feeding damage can be eliminated by controlling sheet feeding, sheet feeding, and conveyance speeds based on the detected thickness of the sheet S. In addition, when the thickness of the detected sheet S is a non-conveyable thickness, it is possible to take appropriate measures such as automatically feeding the sheet, stopping feeding, and conveyance.

  In the above embodiment, the sheet is classified into plain paper, thin paper, and thick paper based on the thickness detected by the sheet thickness detecting means 31. However, when the thickness of the sheet detected by the sheet thickness detecting means 31 is a predetermined thickness or more, the sheet is It is also possible to determine that the sheet has been double-fed, feed the sheet, stop feeding the sheet, and stop the conveyance, and notify that the conveyance is defective.

  FIG. 9 shows the structure of the sheet thickness detection means 41 of the second embodiment. In this embodiment, in addition to the configuration of the sheet thickness detection means 31 of the first embodiment, the expansion and contraction range of the coil spring 34 is within the expansion and contraction range of the coil spring 34 detectable by the proximity sensor 35 in order to assist detection by the coil spring 34. A conductive auxiliary detection member 42 is provided which moves in conjunction with the above. The position of the driven roller 27 can be identified by detecting the winding density of the predetermined area of the coil spring 34 and the magnetic loss corresponding to the area of the predetermined area of the auxiliary detection member 42.

  The auxiliary detection member 42 is formed of a conductive member such as a metal plate of various shapes whose shape changes along the expansion and contraction direction of the coil spring 34 from the upper surface of the bearing member 32. This metal plate is shaped such that the lateral width or thickness changes linearly in the detection area E of the proximity sensor 35. The shape is set according to the expansion and contraction of the coil spring 34, and the sensor output is reduced in a narrow width or thickness so that the sensor output is low when the coil spring 34 is expanded and compressed when the coil spring 34 is compressed. Make the width wide or thick so as to be higher. As shown in FIG. 9 as such a shape, it is possible to use a triangular metal plate in which one of the expansion and contraction directions of the coil spring 34 is at the top and the other is at the bottom.

  By making the shape of the auxiliary detection member 42 into a triangular pattern, it is possible to set the same coarse and dense state as the coil pitch shown in FIG. 8. As a result, even if a sufficient change in sensor output can not be obtained only by the change in expansion and contraction of the coil spring 34, the change in pattern of the auxiliary detection member 42 can increase the detection sensitivity of the proximity sensor 35.

  Next, the configuration of the sheet size detection means 51 is shown in FIG. The sheet size detection unit 51 is provided so as to be movable in a direction away from or in contact with the sheet S. The sheet tray 11 for stacking the sheet S, the sheet feeding unit for feeding the sheet S on the sheet tray 11, A first restricting plate 52 and a second restricting plate 53 (detected member) for restricting one end of the sheet S on the tray 11, and a coil spring 34 for urging the second restricting plate 53 toward the sheet S, The size of the sheet S is detected based on the position of the restricting plate 53. The second restricting plate 53 is movably provided in the slide groove 54 formed in the bottom of the storage case 9, and is moved according to the size of the sheet S, and the rear of the sheet S stacked on the stacking tray 11 is moved. The end is regulated to align the leading end with the transport roller pair 25 side.

  The sheet size detection unit 51 includes a position detection mechanism 37 having the same configuration as that of the sheet thickness detection unit 31 described above. The position detection mechanism 37 is disposed in the vicinity of a coil spring 34 disposed between one end of the storage case 9 and the second restricting plate 53 and a direction orthogonal to the expansion and contraction direction of the coil spring 34. And a proximity sensor 35 for specifying the position of the second restricting plate 53. The configurations of the coil spring 34 and the proximity sensor 35 are the same as in the first and second embodiments, and thus the description thereof is omitted.

  After the sheet S of a predetermined size is placed on the stacking tray 11 and the width direction is regulated by the pair of first regulation plates 52, the second regulation plate 53 is slid to regulate the rear end of the sheet S. By sliding the second restricting plate 53, the coil spring 34 expands, and the winding density changes according to the width of the coil pitch of the coil spring 34 at this time. The proximity sensor 35 detects the change in the winding density in the predetermined detection area E, whereby the position of the second restricting plate 53 is detected, and the sheet size can be determined.

  If the size of the sheet S is small, the coil pitch is wide, and if the size of the sheet S is large, the coil pitch is narrow. A sheet set in the stacking tray 11 and regulated by the second regulation plate 53 by measuring and storing in advance the relationship between the output value of the proximity sensor 35 that detects such a change in coil pitch and the sheet size. The size of can be determined. Further, as in the case of the sheet thickness detection means 41 shown in FIG. 9, the sheet size can be more reliably determined by providing the auxiliary detection member 42 in parallel along the expansion and contraction direction of the coil spring 34.

  According to the sheet size detection unit 51 described above, sheet feeding and sheet feeding and sheet feeding can be appropriately controlled according to the detected sheet size, whereby sheet jamming and sheet damage can be eliminated. In addition, when the size of the detected sheet is a size that can not be conveyed, the sheet can be automatically fed out, fed and conveyed, and conveyance defects can be prevented beforehand.

E detection area S sheet 1 image forming apparatus system 2 image forming apparatus 3 document reading apparatus 4 document feeding apparatus 5 sheet feeding apparatus 6 stacking apparatus 7a, 7b sheet feeding cassette 8 sheet discharge roller pair 9 storage 11 stacking tray 12 opening 13 Lifting mechanism 21 paper feed unit 22 feed roller 23 separation roller 24 paper feed roller 25 transport roller pair 26 drive roller 27 driven roller (detected member)
28 1st shaft 29 2nd shaft 30a lower guide plate 30b upper guide plate 31 sheet thickness detection means 32 bearing member 33 bearing bracket 34 coil spring 35 proximity sensor (inductive proximity sensor)
36 mounting plate 37 position detection mechanism 41 sheet thickness detection means 42 auxiliary detection member 51 sheet size detection means 52 first regulation plate 53 second regulation plate (detection member)

Claims (9)

A position detection mechanism for detecting the position of a detection target member,
A coil spring that expands and contracts with the movement of the detection target member, and an inductive proximity sensor that detects an expansion and contraction state of the coil spring,
A position detection mechanism which specifies the position of the detected member based on the expansion and contraction state of the coil spring detected by the inductive proximity sensor. One end portion of the coil spring is fixed, and the other end portion of the coil spring is disposed so as to be expandable and contractable with the movement of the detection target member.
The position detection mechanism according to claim 1, wherein the inductive proximity sensor is disposed on one end side of the coil spring and in the vicinity of an outer periphery of the coil spring.   The position detection mechanism according to claim 1, wherein the inductive proximity sensor detects a winding density of a predetermined area in the coil spring, and specifies the position of the detection target based on the winding density. A conductive auxiliary detection member that moves in conjunction with the expansion and contraction of the coil spring is provided within the expansion and contraction range of the coil spring that can be detected by the inductive proximity sensor.
The position of the detected member is specified by detecting the winding density of the predetermined region of the coil spring and the magnetic loss corresponding to the area of the predetermined region of the auxiliary detection member by the inductive proximity sensor. The position detection mechanism according to any one of the above.   The position detection mechanism according to claim 4, wherein the auxiliary detection member is formed of a conductive member whose shape changes along the expansion and contraction direction of the coil spring.   The position detection mechanism according to claim 4 or 5, wherein the auxiliary detection member is formed of a triangular metal plate whose apex is one of expansion and contraction directions of the coil spring and the other is a base. A stacking tray for stacking sheets, a sheet feeding roller for feeding sheets on the stacking tray, a pair of conveying rollers disposed on the downstream side of the sheet feeding direction of the sheet feeding roller and conveying the sheet with a pair of sheets A bearing member rotatably supporting one of the transport rollers, a bearing bracket slidably holding the bearing member in the vertical direction, and one transport roller supported by the bearing member on the other transport roller side A coil spring for urging the sheet, and a sheet thickness detecting means for detecting the thickness of the sheet sandwiched between the pair of conveying rollers from the position of one of the conveying rollers;
The sheet thickness detection means is disposed in the vicinity of a direction orthogonal to the expansion and contraction direction of the coil spring, and includes an inductive proximity sensor for detecting a change in shape when the coil spring is expanded and contracted. The coil spring detected by the inductive proximity sensor A sheet feeding device for identifying a position of one of the conveyance rollers supported by the bearing member based on a change in shape of the sheet; A stacking tray for stacking the sheets, a sheet feeding unit for feeding the sheets on the stacking tray, a regulating plate movably provided in a direction away from or in contact with the sheets, and regulating one end of the sheets on the stacking tray; A coil spring biasing the restriction plate toward the sheet, and a sheet size detection unit detecting the size of the sheet based on the position of the restriction plate;
The sheet size detection means is disposed in the vicinity of a direction orthogonal to the expansion and contraction direction of the coil spring, and includes an inductive proximity sensor that detects a change in shape when the coil spring is expanded and contracted. The coil spring detected by the inductive proximity sensor A sheet feeding device for specifying the position of the restriction plate based on the change in shape of the sheet.   The sheet feeding device according to claim 7, wherein the inductive proximity sensor detects a change in coil pitch accompanying expansion and contraction of the coil spring.

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