JP2017226499A - Medium conveyance device and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent paper powder from accumulating and adhering to a sensor light transmission surface of an optical sensor when conveying media having different thickness in a medium conveyance path where the optical sensor is arranged.SOLUTION: A sheet guide lower 5 of a medium conveyance path R is formed in a manner capable of contacting/separating in the vertical direction with respect to a sheet guide upper 3, and a feed roller lower 9 is installed in a manner capable of contacting/separating in the vertical direction. A prism 21 through which the sensor light of the optical sensor is transmitted and a skew sensor cover 29 are arranged on a conveyance surface 5s of the sheet guide lower 5, and the height of the sensor light transmission surfaces 22a, 22b and 30a are made to be slightly higher than the conveyance surface 5s. With this configuration, accumulating and adhering paper powder is automatically removed by conveyance of a thin sheet Ma or a thick sheet Mb.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a medium conveying apparatus capable of conveying a medium.

  In general, an image forming apparatus that prints an image on a sheet or the like includes a sheet conveyance device that conveys the sheet or the like through a sheet conveyance path, and performs printing on the conveyed sheet or the like by a print head or the like of the printing apparatus. This sheet conveyance path is formed by an upper guide member and a lower guide member that are arranged in parallel in the vertical direction. In order to transport sheets or the like having different thicknesses, a configuration is adopted in which the sheets are transported by making the upper guide member detachable in the vertical direction with respect to the lower guide member (for example, Japanese Patent Laid-Open No. 2009-2009). 84007 (see Patent Document 1).

  In the sheet conveying apparatus having such a configuration, in order to control the conveyance of the sheet or the like, the table sensor for detecting the sheet or the like set by the operator and the skew sensor for detecting the skew of the sheet or the like are fixed on the fixed sheet guide lower side. Placed in. As the table sensor and the skew sensor, it is preferable to use a mechanical sensor that is not easily affected by paper dust. However, when using a thick paper having a thickness of about 0.1 mm to a thick paper exceeding 2 mm, the mechanical sensor is used. In this case, it is preferable to use an optical sensor because a detection error is likely to occur.

JP 2009-84007 A

  However, in the paper transport device having the above configuration, the paper dust is most easily deposited and adhered to the transport surface of the lower guide member, and the paper dust is also deposited and adhered to the transport surface where the sensor light of the optical sensor is transmitted. For this reason, there is a problem that erroneous detection that the sensor light is blocked and it is determined that there is no paper or the like occurs.

  An object of the present invention is to solve such a problem. In a medium transport apparatus that transports media having different thicknesses by a medium transport path in which an optical sensor is arranged, the sensor light of the optical sensor in the lower guide member is transmitted. An object of the present invention is to provide a medium transport apparatus capable of automatically removing paper dust deposited and adhered to a transport surface at a position where the paper is transported by paper transport.

  In order to solve the above problems, a medium transport apparatus according to the present invention described in claim 1 is a medium transport apparatus that transports media having different thicknesses by a medium transport path in which an optical sensor is arranged, and the medium transport path includes: An upper guide member and a lower guide member that can be moved up and down with respect to the upper guide member are formed. The lower guide member transmits sensor light of the optical sensor to a transport surface on which the medium is transported. A light transmissive member is disposed, and the height of the sensor light transmissive surface of the light transmissive member is slightly higher than the transport surface.

  The medium conveying apparatus according to the second aspect of the present invention includes a first urging member that urges the lower guide member in the direction of the upper guide member, an upper feed roller and a lower feed roller that convey the medium, A first shaft that rotatably supports the lower feed roller, and a second urging member that urges the lower feed roller in the direction of the upper feed roller.

According to a third aspect of the present invention, there is provided the medium conveying device according to the present invention, wherein the lower guide member is further provided with a limiter that restricts movement of the first shaft in the vertical direction within a predetermined range.
According to a fourth aspect of the present invention, there is provided the medium carrying device according to the present invention, wherein the light transmitting member is a prism for guiding sensor light of the optical sensor.
According to a fifth aspect of the present invention, there is provided the medium conveying apparatus according to the present invention, wherein the light transmitting member is a sensor cover provided on the conveying surface of the medium conveying path.

  According to the present invention, in the medium transport apparatus that transports media having different thicknesses by the medium transport path in which the optical sensor is disposed, the medium transport path is formed in the vertical direction with respect to the upper guide member and the upper guide member. The lower guide member is formed of a detachable lower guide member, and the lower guide member has a light transmission member that transmits the sensor light of the optical sensor on the transport surface, and the height of the sensor light transmission surface of the light transmission member is Since the height is slightly higher than the conveyance surface, paper dust deposited and adhered to the sensor light transmission surface by the medium conveyance can be automatically removed.

1 is a perspective view of a printer according to a first embodiment. FIG. 3 is a perspective view illustrating a sheet guide lower of the sheet conveying device in the printer according to the first embodiment. FIG. 3 is a side view of the vicinity of a sheet guide lower viewed from the direction of arrow B in FIG. 2. It is X1-X1 sectional drawing in FIG. FIG. 6 is an explanatory diagram illustrating a cross section around a feed roller upper and a feed roller lower of the sheet conveying device according to the first embodiment. FIG. 6 is an explanatory diagram illustrating a cross section around a feed roller upper and a feed roller lower of the sheet conveying device according to the first embodiment. FIG. 3 is a perspective view of the sheet guide upper of the sheet conveying apparatus according to the first embodiment viewed from the upper front side of the apparatus. FIG. 3 is a perspective view of the sensor substrate of the sheet guide upper of the sheet conveying apparatus according to the first embodiment when viewed from the lower rear side of the apparatus. FIG. 3 is a perspective view of the sheet guide upper of the sheet conveying apparatus according to the first embodiment when viewed from the lower rear side of the apparatus. FIG. 3 is a perspective view of the sheet guide lower of the sheet conveying apparatus according to the first embodiment when viewed from the upper front side of the apparatus. FIG. 6 is a bottom view of a sheet guide lower of the sheet conveying device according to the first embodiment. FIG. 4 is a cross-sectional view of the sheet conveying apparatus according to the first embodiment around a feed roller upper and a feed roller lower. FIG. 3 is a layout diagram of a skew sensor substrate and a skew sensor light emitting element of the paper conveying apparatus according to the first embodiment. It is the a section enlarged view of FIG. It is explanatory drawing which shows a X3-X3 cross section. It is explanatory drawing which shows a X4-X4 cross section. FIG. 6 is an operation explanatory diagram when a thin sheet is conveyed in the sheet conveying apparatus according to the first embodiment. FIG. 10 is an operation explanatory diagram when transporting a thick sheet in the sheet transport apparatus according to the first embodiment. It is explanatory drawing of the modification of the paper conveying apparatus regarding 1st Embodiment.

(First embodiment)
The configurations of the medium transport device and the image forming apparatus according to the first embodiment of the present invention will be described below. Elements common to the drawings are given the same reference numerals. In the following description of the embodiments, a sheet is used as an example of a medium to be conveyed and printed, but a card-like or booklet-like medium may be used.

  FIG. 1 is a perspective view of the printer according to the first embodiment. A printer 1 as an image forming apparatus includes a sheet conveying apparatus 1a as a medium conveying apparatus that conveys a sheet M as a medium toward the back side of the apparatus, and a sheet M provided at the back side of the apparatus, as indicated by a broken line in the drawing. The printer 1b is configured to perform printing.

  The sheet conveying apparatus 1a receives sheets M having different thicknesses from the direction of arrow A and conveys them to the printing apparatus 1b. The sheet conveying apparatus 1a includes a sheet guide upper 3 as an upper guide member, a sheet guide lower 5 as a lower guide member, and optical sensors such as a table sensor and a skew sensor described later.

  The sheet guide upper 3 has a structure capable of covering the upper part with a sheet guide upper cover 3x as an assembly. The seat guide upper 3 is fixed to the main frame 2, and the seat guide lower 5 is supported and attached to the mechanical chassis 4 so as to be detachable in the arrow Y direction, that is, in the vertical direction of the apparatus, as will be described later. The sheet guide upper 3 is disposed on the upper side of the sheet guide lower 5 so as to face the sheet guide lower 5. A sheet conveyance path R described later is formed by the sheet guide upper 3 and the sheet guide lower 5. A paper insertion slot 5x for inserting the paper M is formed on the front side of the apparatus, and a paper conveyance path R is formed toward the back side of the apparatus.

  The printing apparatus 1b performs predetermined printing on sheets M having different thicknesses. The printing apparatus 1 b includes a print head 51 that performs printing, a slide belt 52 that moves the print head 51 to an arbitrary horizontal position, and a slide shaft 53 that supports the movement of the print head 51. The printing apparatus 1b moves the print head 51 in the paper width direction, and performs printing or the like on the paper M conveyed between the platen 54 provided facing the print head 51.

  Note that the printing apparatus 1b may be an impact type printing apparatus that performs printing via an ink ribbon, an inkjet type printing apparatus, or an electrophotographic printing apparatus. May be.

  The sheet M set on the sheet setting table (not shown) by the operator is sucked from the sheet insertion port 5x of the sheet conveying apparatus 1a, conveyed in the direction of arrow A along the sheet conveying path R, printed by the printing apparatus 1b, Discharged.

  Next, each part will be described. First, the configuration of the sheet guide lower 5 and the feed roller lower 9 will be described. FIG. 2 is a perspective view illustrating a sheet guide lower of the sheet conveying device in the printer according to the first embodiment. In FIG. 2, the upper periphery of the printer 1b and the paper transport device 1a in the printer 1 is omitted. The sheet guide lower 5 is disposed at the lower part of the sheet conveying apparatus 1a, and forms one of the sheet conveying paths R as described above. The sheet guide lower 5 is formed long in the width direction of the paper M.

  The sheet guide lower 5 is supported and attached to the mechanical chassis 4 and guides the sheet M conveyed in the direction of arrow A from below. The sheet guide lower 5 includes a feed roller lower 9 as a lower feed roller that conveys the paper M, table sensor light transmission surfaces 22a and 22b through which sensor light for detecting the paper M is transmitted, and a skew sensor light transmission surface 30a. Is placed. A plurality of feed roller lowers 9 are provided in the vicinity of the top of the mountain shape shown in FIG. The table sensor light transmission surfaces 22 a and 22 b are provided on the upstream side of the paper conveyance of the feed roller lower 9, and the skew sensor light transmission surface 30 a is provided on the downstream side of the paper conveyance of the feed roller lower 9.

  3 is a side view of the periphery of the sheet guide lower viewed from the direction of arrow B in FIG. 2, and FIG. 4 is a cross-sectional view taken along line X1-X1 in FIG. As shown in FIG. 3, the sheet guide lower 5 has a mountain shape, and has a shape in which the vicinity of the top is a lower conveyance surface 5 s that forms the sheet conveyance path R.

  The protruding portion 9-2 as a part of the circumference of the feed roller lower 9 protrudes from the lower conveyance surface 5 s of the sheet guide lower 5 and enters the paper conveyance path R. The sheet guide lower 5 is urged in the direction of the sheet guide upper 3 as the arrow Y1 direction by a spring 6b as a first urging member. Both ends of the spring 6 b are supported by a spring holder 7 b disposed in the mechanical chassis 4 and a lower end portion 5 b of the sheet guide lower 5.

  Then, as shown in FIG. 4, the left and right ends of the sheet guide lower 5 exert a biasing force of about 50 gf in total in the arrow Y1 direction, that is, the sheet guide upper 3 direction, by springs 6a and 6b as first biasing members. It is applied and pressed while maintaining a certain distance from the sheet guide upper 3. Accordingly, the upper and lower ends of the springs 6a and 6b are supported by the spring holders 7a and 7b disposed on the mechanical chassis 4 and the lower ends 5a and 5b of the sheet guide lower 5, respectively.

  Next, the sheet guide upper 3 and the sheet guide lower 5 constituting the sheet transport path R will be described. FIG. 5 is an explanatory view showing a cross section of the periphery of the feed roller upper and the feed roller lower of the sheet conveying apparatus according to the first embodiment. FIG. 5 shows a cross section of the periphery of the lower shaft 25 between the plurality of feed roller lowers 9 other than both ends in the paper width direction. The sheet guide upper 3 is substantially planar and has an upper conveyance surface 3 s that forms a sheet conveyance path R. The upper conveying surface 3s is provided with a roller hole 3-2, and a protruding portion 8-2 as a part of a feed roller upper 8 as an upper feed roller protrudes.

  The sheet guide lower 5 has a lower conveyance surface 5s in which the cross section is a mountain shape and the vicinity of the top forms a sheet conveyance path R. The lower conveying surface 5s is provided with a roller hole 5-2, and a protruding portion 9-2 of the feed roller lower 9 protrudes. Accordingly, the respective roller protrusions 8-2 and 9-2 protrude in the paper transport path R. Further, a sheet insertion opening 5x is formed on the most upstream side of the sheet conveyance path R formed by the sheet guide upper 3 and the sheet guide lower 5.

  The sheet guide lower 5 is pushed down in the direction of the arrow Y2 by the thickness of the conveyed paper M while being pushed up in the direction of the sheet guide upper 3 by the urging force of the springs 6a and 6b shown in FIG. Therefore, the sheet guide lower 5 can guide the sheet M to the roller contact position 10 a while maintaining a distance corresponding to the thickness of the sheet M between the sheet guide upper 3 and the sheet guide upper 3.

  Next, the feed roller upper 8 and the feed roller lower 9 that transport the paper M will be described. FIG. 6 is an explanatory diagram illustrating a cross section of the periphery of the feed roller upper and the feed roller lower of the sheet conveying device according to the first embodiment. FIG. 6 shows a cross section in which the periphery of the lower shaft 25 between the plurality of feed roller lowers 9 at one end of the both ends in the paper width direction is cut.

  A plurality of feed roller uppers 8 are disposed on the upper portion of the sheet guide upper 3. The feed roller lower 9 is disposed below the sheet guide lower 5 so as to face the feed roller upper 8. As described above, the feed roller lower 9 is supported by the mechanical chassis 4 and can be separated from the feed roller upper 8 only in the vertical direction, that is, in the directions of the arrows Y2 and Y1. The feed roller upper 8 is fixed to the main frame 2 so as not to move, and rotates by receiving a driving force from a driving source (not shown).

  In other words, the feed roller lower 9 has a lower shaft as a first shaft via a tension plate 12 that can rotate an urging force urged from a tension spring 11 as a second urging member by a support shaft 12a. Receive 25. As a result, the feed roller lower 9 is urged in the direction of the arrow Y1. By this urging force, the protruding portion 9-2 of the feed roller lower 9 is brought into contact with the protruding portion 8-2 of the feed roller upper 8 to generate a feed force for the paper M.

  The tension spring 11 and the tension plate 12 may be provided between the plurality of feed roller lowers 9 or may be provided only at both ends in the paper width direction of the paper transport device 1a.

  Further, when the paper M conveyed from the direction of arrow A reaches the roller contact position 10a, the feed roller lower 9 is pressed against the feed roller upper 8 by the urging force of the tension spring 11 shown in FIG. Is pushed down in the direction of the arrow Y2 in accordance with the thickness of. As a result, the feed roller lower 9 can transport the paper M while maintaining a distance corresponding to the thickness of the paper M with the feed roller upper 8.

  Next, the arrangement configuration of the optical sensors on the sheet guide upper 3 side of the sheet conveying apparatus 1a according to the first embodiment will be described. FIG. 7 is a perspective view of the sheet guide upper of the sheet conveying apparatus according to the first embodiment viewed from the upper front side of the apparatus. FIG. 8 is a perspective view of the sensor substrate of the sheet guide upper of the sheet conveying apparatus according to the first embodiment as viewed from the lower rear side of the apparatus. As shown in FIG. 7, the sensor substrate 14 is disposed between the upper shaft 13 of the feed roller upper 8 and the sheet guide upper 3.

  As shown in FIG. 8, a plurality of table sensor light emitting elements 16 and table sensor light receiving elements 17 are provided in the direction of arrow A, that is, in a direction perpendicular to the paper transport direction, on the upstream side of the paper transport on the lower surface of the sensor substrate 14. Are alternately arranged in a row. The plurality of table sensor light emitting elements 16 and the table sensor light receiving element 17 are used as table sensors for detecting paper set by an operator.

  Further, a plurality of skew sensor light receiving elements 19 are arranged in a line in the direction of arrow A, that is, in the direction perpendicular to the paper transport direction, on the downstream side of the paper transport on the lower surface of the sensor substrate 14. The plurality of skew sensor light receiving elements 19 are used as skew sensors for aligning the leading edge of the paper and controlling skew correction.

  FIG. 9 is a perspective view of the sheet guide upper of the sheet conveying apparatus according to the first embodiment viewed from the lower rear side of the apparatus. The upper conveyance surface 3 s of the sheet guide upper 3 forms a sheet conveyance path R for the sheet M. The sheet M is conveyed along the sheet conveyance path R from the direction of arrow A. As shown in FIG. 9, the sheet guide upper 3 is arranged in the same manner as each element so as not to hinder light emission from the table sensor light emitting element 16 and light reception to the table sensor light receiving element 17 of the sensor substrate 14 shown in FIG. 8. A plurality of table sensor openings 20a are provided. The table sensor opening 20a allows table sensor light 16x (see FIG. 15) from the table sensor light emitting element 16 of the sensor substrate 14 or table sensor light 16x to the table sensor light receiving element 17 to pass through.

  Similarly, a plurality of skew sensor openings 20b are provided in the same arrangement as the skew sensor light receiving elements 19 of the sensor substrate 14 as shown in FIG. Skew sensor light 27x (see FIG. 16) to the skew sensor light receiving element 19 of the sensor substrate 14 passes through the skew sensor opening 20b. The table sensor opening 20a and the skew sensor opening 20b are provided toward the paper transport path R.

  Next, the arrangement configuration of the optical sensors on the sheet guide lower 5 side in the sheet conveying apparatus 1a according to the first embodiment will be described. FIG. 10 is a perspective view of the sheet guide lower of the sheet conveying apparatus according to the first embodiment viewed from the upper front side of the apparatus. The lower conveyance surface 5 s of the sheet guide lower 5 forms a paper conveyance path R for the paper M. The sheet M is conveyed along the sheet conveyance path R from the direction of arrow A. A prism 21 as a first light transmitting member, which will be described later with reference to FIG. 11, is disposed on the upstream side of the sheet conveyance on the lower conveyance surface 5s of the sheet guide lower 5. The table sensor light transmission surface 22a that is the incident surface of the prism 21 and the table sensor light transmission surface 22b that is the emission surface are flat with no angle with respect to the lower conveyance surface 5s of the sheet guide lower 5, that is, parallel to the conveyance direction. Placed in.

  The table sensor light transmission surface 22a is arranged to face the table sensor opening 20a through which the table sensor light 16x (see FIG. 15) from the table sensor light emitting element 16 of the sensor substrate 14 described above passes. Similarly, the table sensor light transmission surface 22b is disposed to face the table sensor opening 20a through which the table sensor light 16x to the table sensor light receiving element 17 of the sensor substrate 14 passes. Thereby, the table sensor light 16x from the table sensor light emitting element 16 and the table sensor light 16x to the table sensor light receiving element 17 can enter the paper transport path R.

  Further, a skew sensor cover 29 as a second light transmission member, which will be described later with reference to FIG. 11, is disposed on the downstream side of the sheet conveyance on the lower conveyance surface 5 s of the sheet guide lower 5. The skew sensor light transmission surface 30a, which is the emission surface at the upper end of the skew sensor cover 29, is disposed as a plane having no angle with respect to the lower conveyance surface 5s of the sheet guide lower 5, that is, parallel to the conveyance direction. The skew sensor light transmission surface 30a is disposed to face a position where skew sensor light 27x from a skew sensor light emitting element 27 described later is transmitted. Accordingly, the skew sensor light 27x from the skew sensor light emitting element 27 can enter the paper transport path R.

  At both ends of the sheet guide lower 5 in the sheet width direction, limiters 23a and 23b that limit the movement of the lower shaft 25 in the vertical direction within a predetermined range are disposed. Details will be described later.

  Next, a configuration related to the optical sensor on the lower surface side of the sheet guide lower 5 of the sheet conveying apparatus 1a according to the first embodiment will be described. FIG. 11 is a bottom view of the sheet guide lower of the sheet conveying apparatus according to the first embodiment. The sheet M is conveyed in the direction indicated by the arrow A. The prism 21 as the first light transmitting member is disposed on the upstream side of the sheet conveyance on the lower surface side of the sheet guide lower 5.

  The prism 21 guides the table sensor light 16x from the table sensor light emitting element 16 of the sensor substrate 14 shown in FIG. The table sensor light transmission surface 22a and the table sensor light transmission surface 22b shown in FIG. 10, which are the entrance surfaces of the prism 21, and the table sensor light transmission surface 16b of the sensor substrate 14 with the sheet conveyance path R interposed therebetween, respectively. It is arranged opposite to the position of the light receiving element 17. The prism 21 is preferably made of a material such as a polycarbonate resin plastic having a high light transmittance.

  A skew sensor cover 29 is disposed on the downstream side of the sheet conveyance on the lower surface side of the sheet guide lower 5. The skew sensor cover 29 guides skew sensor light 27x from a skew sensor light emitting element 27, which will be described later, to the skew sensor light receiving element 19 of the sensor substrate 14 with the paper transport path R interposed therebetween. The skew sensor cover 29 is arranged according to the position of the skew sensor light emitting element 27. The skew sensor cover 29 is also preferably made of a material such as polycarbonate resin plastic having a high light transmittance.

  Next, the positional relationship of the optical sensors of the paper transport apparatus 1a relating to the first embodiment will be described. FIG. 12 is a cross-sectional view around the feed roller upper and the feed roller lower of the sheet conveying apparatus according to the first embodiment. FIG. 12 shows that the position of the X2-X2 plane shown in FIG. 11 is cut for the seed guide lower 5.

  As shown in FIG. 12, the paper M is sucked from the paper insertion opening 5x. A sensor substrate 14 on which the table sensor light emitting element 16 and the table sensor light receiving element 17 are arranged is attached to the sheet guide upper 3. A prism 21 having table sensor light transmission surfaces 22 a and 22 b facing the table sensor light emitting element 16 and the table sensor light receiving element 17 is disposed on the lower surface of the sheet guide lower 5 on the upstream side of the sheet conveyance.

  Further, a skew sensor substrate 28 (see FIG. 13) fixed vertically to the mechanical chassis 4 is disposed below the sheet guide lower 5 on the downstream side of the sheet conveyance. FIG. 13 is a layout diagram of the skew sensor substrate of the sheet conveying apparatus according to the first embodiment. On the skew sensor substrate 28 provided vertically, the skew sensor light emitting element 27 is disposed so as to face the skew sensor light receiving element 19 disposed on the sensor substrate 14 of the sheet guide upper 3.

  Further, the sheet guide lower 5 is provided with a skew sensor cover 29 through which the skew sensor light 27x emitted from the skew sensor light emitting element 27 is transmitted. The skew sensor cover 29 also has a function of preventing paper dust deposited and attached on the lower conveyance surface 5 s of the sheet guide lower 5 from dropping onto the skew sensor light emitting element 27.

  Further, a shutter 18 supported by a shutter slide shaft 18a is provided below the sheet guide lower 5 on the downstream side of the sheet conveyance, and when the skew of the sheet M is detected by the skew sensor light receiving element 19, the direction of the arrow Y1 is provided. That is, the sheet is raised in the direction of the sheet conveyance path R, the sheet conveyance path R is blocked, and the skew of the sheet M is corrected. When the skew is not detected or when the skew is corrected, the shutter 18 is lowered in the direction of the arrow Y2 to open the paper transport path R.

  Next, the configuration of the prism 21 and the skew sensor cover 29 will be described in detail. FIG. 14 is an enlarged view of part a in FIG. The table sensor light transmitting surfaces 22a and 22b, which are the entrance surface and the exit surface of the prism 21 used as the table sensor, are arranged at positions facing the table sensor light emitting element 16 and the table sensor light receiving element 17. The heights of the table sensor light transmission surfaces 22a and 22b are slightly higher by t1 than the lower conveyance surface 5s of the sheet guide lower 5 as the conveyance surface, and further t2 minutes from the roller contact position 10a. make low. The table sensor light transmission surfaces 22a and 22b are flat surfaces having no angle with respect to the transport direction, that is, planes parallel to the transport direction.

  The height t1 is from over 0 mm to about 0.1 mm so that the transported paper M abuts against the table sensor light transmission surfaces 22a and 22b and rubs, and the transport jam does not occur. It is good to do. Further, the height t2 is the largest sheet so that even a thick sheet of about 2 mm can be smoothly conveyed to the roller contact position 10a and the sheet M can be rubbed against the table sensor light transmission surfaces 22a and 22b. The thickness is preferably about 0.9 to 1 mm near the center value of the thickness.

  On the other hand, the upper conveying surface 3s on the sheet guide upper 3 side is disposed at a position higher by t3 than the roller contact position 10a. The height t3 is preferably about 0.5 mm so that the roller protruding portion 8-2 of the feed roller upper 8 protrudes from the upper conveying surface 3s of the sheet guide upper 3 to reliably convey even a thin sheet. .

  Similar to the table sensor light transmission surfaces 22a and 22b of the prism 21, the skew sensor light transmission surface 30a on the top of the skew sensor cover 29 is a plane having no angle with respect to the conveyance direction, that is, a plane parallel to the conveyance direction. It is. The height of the sheet guide lower 5 is slightly higher than the lower conveyance surface 5s by the height t1. The height t1 of the skew sensor light transmission surface 30a is also set to be about 0 mm or more from about 0 mm so that the conveyed paper M abuts against the skew sensor light transmission surface 30a and rubs, and no conveyance jam occurs. It should be 1 mm.

  Next, returning to FIG. 12, the limiter 23 will be described. The limiter 23 restricts the lower shaft 25 as the first shaft from moving in a predetermined range in the vertical direction as described above. The lower limit 24 of the limiter 23 limits the downward movement of the lower shaft 25 of the feed roller lower 9. The upper limit 26 of the limiter 23 limits the upward movement of the lower shaft 25.

  Here, the position of the lower limit 24 of the limiter 23 is set based on the height t2 from the table sensor light transmission surfaces 22a and 22b to the roller contact position 10a. On the other hand, the position of the upper limit 26 of the limiter 23 is set such that when the thick sheet Mb is conveyed, the sheet guide lower 5 is lowered and the sheet insertion opening 5x is opened in a range where the lower shaft 25 is not limited by the upper limit 26. .

  With the above configuration, the sheet conveying apparatus 1a according to the first embodiment operates as follows. First, the detection operation of the paper M by the table sensor of the paper transport apparatus 1a will be described. FIG. 15 is an explanatory diagram showing an X3-X3 cross section. In FIG. 15, the paper M is conveyed from the back side to the front side.

  The table sensor light 16 x is emitted from the table sensor light emitting element 16 of the sensor substrate 14 attached to the sheet guide upper 3. The table sensor light 16 x passes through the table sensor opening 20 a of the sheet guide upper 3 and enters the paper transport path R. Thereafter, the table sensor light 16x is incident from a table sensor light transmitting surface 22a as an incident surface of the prism 21 attached to the sheet guide lower 5.

  Further, the table sensor light 16x is transmitted through the prism 21 while being repeatedly reflected by a 45 degree mirror surface inside the prism 21, and is emitted from the table sensor light transmission surface 22b as the emission surface of the prism 21. Then, the table sensor light 16x enters the paper transport path R again. Thereafter, the table sensor light 16 x passes through the table sensor opening 20 a and is received by the table sensor light receiving element 17 of the sensor substrate 14.

  With this optical path, when the table sensor light 16x is received by the table sensor light receiving element 17, it is determined that the table sensor light 16x is not blocked by the paper M and there is no paper M. When the table sensor light 16x is blocked and is not received by the table sensor light receiving element 17, it is determined that there is a sheet M. In this way, the presence or absence of the paper M passing on the prism 21 can be detected by the table sensor.

  Next, the detection operation of the paper M by the skew sensor of the paper transport apparatus 1a will be described. FIG. 16 is an explanatory diagram showing the X4-X4 cross section. In the cross-sectional view of FIG. 16, the paper M is transported from the back side to the front side.

  The skew sensor light 27 x is emitted from the skew sensor light emitting element 27 disposed on the skew sensor substrate 28 provided vertically below the sheet guide lower 5, and passes through the skew sensor cover 29 attached to the sheet guide lower 5. To do. Then, the skew sensor light 27x exits the skew sensor light transmission surface 30a and enters the paper transport path R. Further, the skew sensor light 27 x passes through the skew sensor opening 20 b of the sheet guide upper 3 and is received by the skew sensor light receiving element 19 of the sensor substrate 14 attached to the sheet guide upper 3.

  With such an optical path, it is determined that there is no sheet M at the position where the skew sensor light 27x emitted from the skew sensor light receiving element 19 is received by the skew sensor light receiving element 19. Further, it is determined that the sheet M is present at a position where the skew sensor light receiving element 19 does not receive the skew sensor light 27x. As described above, the skew state of the paper M can be determined by detecting the timing of the presence of the paper M at each position by the plurality of skew sensors.

Next, the operation of the sheet conveying apparatus 1a relating to the first embodiment when conveying the sheet M will be described. First, the operation of the sheet conveying apparatus 1a relating to the first embodiment when conveying a thin sheet Ma will be described.
FIG. 17 is an operation explanatory diagram when a thin sheet is conveyed in the sheet conveying apparatus according to the first embodiment.

  When the thin paper Ma is transported, the sheet guide lower 5 is transported without being pushed down in the arrow Y2 direction by the thin paper Ma. At this time, the seat guide lower 5 is pushed up via the lower end portions 5a and 5b of the sheet guide lower 5 by the urging force in the arrow Y1 direction by the springs 6a and 6b, and does not move in the arrow Y2 direction. The position shown at 17 is maintained.

  The sheet guide lower 5 is provided with a prism 21 having table sensor light transmission surfaces 22a and 22b and a skew sensor cover 29 having a skew sensor light transmission surface 30a, and these also move without moving in the arrow Y2 direction. The position shown in FIG.

  Even when the thin paper Ma is transported to the roller contact position 10a, the paper Ma is thin, so that the lower shaft 25 is pushed up in the direction of the arrow Y1 via the tension plate 12 by the urging force of the tension spring 11. The feed roller upper 8 and the feed roller lower 9 convey the thin paper Ma while keeping the contacted position.

  Here, when the paper Ma is thin, the thin paper Ma is conveyed while generating some warping and bending. For this reason, the thin paper Ma conveyed from the paper insertion slot 5x as shown by the arrow a intermittently contacts the table sensor light transmission surfaces 22a and 22b slightly higher than the lower conveyance surface 5s of the sheet guide lower 5. become. As a result, when the thin paper Ma is conveyed, the paper dust deposited and adhered on the table sensor light transmission surfaces 22a and 22b is automatically removed by the thin paper Ma.

  Similarly, when the thin paper Ma is transported, the thin paper Ma abuts intermittently on the skew sensor light transmitting surface 30a on the downstream side of the paper transport and rubs against the skew sensor light transmitting surface 30a. The deposited and adhered paper dust is automatically removed by the thin paper Ma.

Next, the operation when transporting the thick paper Mb will be described. FIG. 18 is an operation explanatory diagram when a thick sheet is conveyed in the sheet conveying apparatus according to the first embodiment.
First, when the leading edge of the thick sheet Mb is conveyed from the sheet insertion slot 5x as indicated by the arrow A, the sheet guide lower 5 is pushed down in the direction of the arrow Y2 by the thickness of the leading end of the thick sheet Mb, and the sheet guide upper 3 The sheet conveyance path R formed by the sheet guide lower 5 is widened.

  As described above, the sheet guide lower 5 is provided with the prism 21 having the table sensor light transmission surfaces 22a and 22b and the sensor cover 29 having the skew sensor light transmission surface 30a. Move in the direction.

  At this time, the sheet guide lower 5 is pushed up in the direction of the arrow Y1 by the urging force of the spring 6, and the table sensor light transmission surfaces 22a and 22b are pressed against the thick paper Mb with a pressure that does not interfere with the paper conveyance.

  Then, as in the case of transporting the thin paper Ma described above, the thick paper Mb abuts against the table sensor light transmitting surfaces 22a and 22b slightly higher than the lower transport surface 5s of the sheet guide lower 5 and rubs to transmit the table sensor light. The paper dust deposited and adhered on the surfaces 22a and 22b is automatically removed by the thick paper Mb.

  Further, when the leading edge of the thick paper Mb is conveyed to the roller contact position 10a, the feed roller lower 9 is biased by the tension spring 11 to the lower shaft 25 due to the thickness of the thick paper Mb as shown in FIG. Pushed down against. At this time, the above-described position of the sheet guide lower 5 is maintained, and the position of the prism 21 disposed in the sheet guide lower 5 is also maintained. Accordingly, the table sensor light transmission surfaces 22a and 22b remain at the positions described above, and the thick paper Mb continues to rub against the table sensor light transmission surfaces 22a and 22b, and accumulates on and adheres to the table sensor light transmission surfaces 22a and 22b. The removed paper dust is further removed.

  Further, when the thick paper Mb is conveyed in the direction of arrow A, the thick paper Mb passes through the roller contact position 10a. Also at this time, the sheet guide lower 5 remains pressed down in the direction of the arrow Y2 due to the thickness of the sheet 10b to be conveyed, and the sheet conveyance path R formed by the sheet guide upper 3 and the sheet guide lower 5 remains widened. It becomes.

  On the other hand, in the feed roller lower 9, the thick paper Mb passes through the roller contact position 10a. Also at this time, the sheet guide lower 5 is such that the lower end portions 5a and 5b of the sheet guide lower 5 are pushed up in the direction of the arrow Y1 by the urging force of the spring 6, and the skew sensor light transmitting surface 30a does not hinder paper conveyance. Pressed against the thick paper Mb.

  Then, as in the case of transporting the thin paper Ma described above, the thick paper Mb abuts against the skew sensor light transmitting surface 30a slightly higher than the transport surface 5a of the sheet guide lower 5 and rubs, and the skew sensor light transmitting surface 30a is rubbed. The paper dust deposited and adhered to is automatically removed.

  As described above, according to the sheet conveying apparatus according to the first embodiment, in the sheet conveying apparatus that conveys the sheet M having a different thickness by the sheet conveying path R in which the optical sensor is arranged, the sheet conveying path R is set to the sheet. The sheet guide lower 5 is formed by a guide upper 3 and a sheet guide lower 5 that can be separated from and attached to the sheet guide upper 3 in the vertical direction. The sheet guide lower 5 has table sensor light transmission surfaces 22a and 22b of the prism 21 on the lower conveying surface 5s. And the height of the table sensor light transmission surfaces 22a and 22b is set slightly higher than the lower conveyance surface 5s, so that the paper dust deposited and adhered to the table sensor light transmission surfaces 22a and 22b is conveyed to the paper M. Can be removed automatically.

  At the same time, the sheet guide lower 5 is arranged such that the skew sensor light transmission surface 30a of the skew sensor cover 29 is disposed on the lower conveyance surface 5s, and the height of the skew sensor light transmission surface 30a is slightly higher than the lower conveyance surface 5s. Therefore, the paper dust deposited and attached to the skew sensor light transmission surface 30a by the conveyance of the paper M can be automatically removed.

  In addition, the sheet guide lower 5 can be separated from the sheet guide upper 3 in the vertical direction, and the sheet guide lower 5 is biased by the springs 6a and 6b from the lower side. The paper dust can be removed by reliably rubbing the table sensor light transmission surfaces 22a and 22b and the skew sensor light transmission surface 30a by the side.

(Modification of the embodiment)
In the description of the paper transport device relating to the above embodiment, the paper transport device of the printer has been described as an example. However, the paper transport device includes a medium transport device that transports media having different thicknesses while detecting the presence or absence of the medium using an optical sensor. If it is an apparatus, the present invention can be applied to a label printer, a card processing apparatus, and the like.

  Further, in the description of the sheet conveying apparatus regarding the above embodiment, the example in which the sheet guide upper 3 side is fixed and the sheet guide lower 5 side can be separated from the sheet guide upper 3 in the vertical direction has been described. The following may be used. In other words, the seat guide lower 5 side may be fixed, and the sheet guide upper 3 side may be separated from the seat guide lower 5 in the vertical direction. Similarly to the sheet conveying apparatus according to the first embodiment, the sheet M to be conveyed is brought into contact with the table sensor light transmission surfaces 22a and 22b and the skew sensor light transmission surface 30a and rubs on the sheet guide lower 5 side. The table sensor light transmission surfaces 22a and 22b and the skew sensor light transmission surface 30a are disposed.

  Further, in the description of the sheet conveying apparatus relating to the above embodiments, the table sensor light transmission surfaces 22a and 22b and the skew sensor light transmission surface 30a are described as planes having no angle with respect to the conveyance direction. May be provided. FIG. 19 is an explanatory diagram of a modified example of the sheet transport device according to the second embodiment.

  As shown by the broken line b in FIG. 19, the table sensor light transmission surfaces 22a and 22b are inclined at a predetermined angle so as to rise in the downstream direction of paper conveyance. That is, the heights of the table sensor light transmission surfaces 22a and 22b are lowered on the upstream side of the sheet conveyance and increased on the downstream side of the sheet conveyance. Similarly, as indicated by a broken line c, the skew sensor light transmission surface 30a is also inclined at a predetermined angle toward the paper transport downstream direction. That is, the height of the skew sensor light transmission surface 30a is lowered on the upstream side of the sheet conveyance and increased on the downstream side of the sheet conveyance.

  In this case, since the paths of the table sensor light 16x from the table sensor light emitting element 16 and the skew sensor light 27x from the skew sensor light emitting element 27 are affected by refraction, the table sensor light emitting element 16, the table sensor light receiving element 17, and the skew are affected. The position of the sensor light receiving element 19 is corrected as appropriate. By adopting such a shape, the paper dust deposited and adhered on the table sensor light transmission surfaces 22a and 22b and the skew sensor light transmission surface 30a can be more efficiently removed.

DESCRIPTION OF SYMBOLS 1 Printer 1a Paper conveyance apparatus 1b Printing apparatus 3 Sheet guide upper 5 Sheet guide lower 5s Conveying surface 6 Spring 8 Feed roller upper 9 Feed roller lower 11 Tension spring 16 Table sensor light emitting element 17 Table sensor light receiving element 19 Skew sensor light receiving element 22a, 22b Table sensor light transmission surface 21 Prism 23 Limiter 25 Lower shaft 27 Skew sensor light emitting element 29 Skew sensor cover 30a Skew sensor light transmission surface

Claims (8)

A medium conveying apparatus for conveying a medium having a different thickness by a medium conveying path in which an optical sensor is arranged,
The medium conveyance path is formed by an upper guide member and a lower guide member that can be moved up and down with respect to the upper guide member.
The lower guide member includes a light transmission member that transmits the sensor light of the optical sensor on a conveyance surface on which the medium is conveyed, and the height of the sensor light transmission surface of the light transmission member is slightly higher than the conveyance surface. A medium conveying apparatus characterized by being made high. A first biasing member that biases the lower guide member in the direction of the upper guide member;
An upper feed roller and a lower feed roller for conveying the medium;
A first shaft that rotatably supports the lower feed roller;
The medium conveying apparatus according to claim 1, further comprising: a second urging member that urges the lower feed roller toward the upper feed roller.   3. The medium conveying apparatus according to claim 2, further comprising a limiter that restricts movement of the first shaft in the vertical direction within a predetermined range on the lower guide member.   The medium conveying apparatus according to claim 1, wherein the light transmitting member is a prism that guides sensor light of the optical sensor.   The medium transport apparatus according to claim 1, wherein the light transmission member is a sensor cover provided on the transport surface of the medium transport path.   The medium conveying apparatus according to claim 1, wherein a height of the sensor light transmitting surface from the conveying surface is set to be greater than 0 mm to approximately 0.1 mm.   2. The medium conveying apparatus according to claim 1, wherein the height of the sensor light transmitting surface of the light transmitting member is set to be lower on the upstream side of paper conveyance and higher on the downstream side of paper conveyance. An image forming apparatus comprising the medium conveying device according to claim 1.

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