JP2020019579A - Sheet conveying device, sheet feeding device, and image forming device - Google Patents

Abstract

To provide a sheet conveying device capable of reducing adhesion of rubber abrasion powder onto a surface (sliding surface) of a suction chamber brought into contact with a belt to thereby prevent adhesive abrasion of the rubber generated in conveying the belt, and inhibiting a sliding resistance between the belt and the suction chamber from being increased, whereby load variation exerted on a drive motor for driving the belt is reduced with passage of time.SOLUTION: A sheet conveying device includes: bridge rollers 22a, 22b as a pair of rollers arranged in parallel at intervals in a sheet conveying direction X; a suction belt 21 formed by a material including rubber having a lot of holes formed thereon and hung over the pair of rollers; a drive motor for driving one of the pair of rollers; a suction chamber 24 arranged between the pair of rollers and having openings on a side of a face sucking a sheet; and a fan for exhausting air in the suction chamber. Fine irregularities 30 as a plurality of concave parts are provided on a surface of the suction chamber brought into contact with the belt in sheet suction in which the sheet is sucked on the belt. The plurality of concave parts have a depth of 40 μm or more.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a sheet conveying device, a sheet feeding device, and an image forming device.

  2. Description of the Related Art An air feeding technology using an air pick type feeding device for feeding a sheet to an image forming unit or an image forming apparatus is known (for example, see Patent Document 1). In this type of sheet feeding device, the sheet is separated by blowing air to a sheet bundle stacked on a sheet stacking table of a sheet feeding tray, and the sheet is floated by blowing air from the leading end side of the sheet. Then, a rubber endless belt with a hole for suction conveyance is arranged on the upper side of the floating paper, and the paper is sucked to the belt by sucking air from the hole of the belt, and further suction to the belt. A separation air is blown between the separated sheet and the other sheets to separate and feed the sheets one by one.

  However, in a conventional air suction conveyance type conveyance device or paper feeding device that absorbs and conveys a sheet to a belt, including Patent Document 1, when a sheet is adsorbed on a suction and conveyance belt, the belt and the belt are conveyed. The surface of the suction chamber which generates negative pressure and which is disposed inside (hereinafter, also referred to as “suction chamber surface”) is in close contact. As a result, when the paper is repeatedly suctioned and conveyed, abrasion powder mainly composed of rubber (hereinafter, referred to as “rubber abrasion powder” or “belt abrasion powder”), which is a scrap of the rubber belt, is generated on the surface of the suction chamber. Adheres to the sliding surface (becomes a sliding surface because the belt is in close contact with the belt and is conveyed in rotation). The abrasion powder becomes tacky due to frictional heat generated when the belt rotates (hereinafter, referred to as “adhesive wear”), and adheres and stays on the sliding surface of the suction chamber surface with time, thereby causing the belt to adhere. There is a problem that the sliding resistance and frictional force between the shaft and the sliding surface of the chamber increase with time, and that a large load is applied to a motor for driving the belt.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and reduces adhesion of belt abrasion powder to the surface (sliding surface) of a suction chamber in contact with a belt, thereby preventing adhesive abrasion generated during belt conveyance. It is another object of the present invention to provide a sheet conveying apparatus capable of suppressing an increase in sliding resistance between a belt and a suction chamber over time.

  In order to achieve the above object, the present invention provides a roller pair arranged at intervals in the sheet conveying direction, a belt that is bridged over the roller pair, and has a plurality of holes, and the roller pair. A sheet transport device, comprising: a suction chamber provided with an opening on a surface on a sheet suction side, and a fan for exhausting air in the suction chamber, wherein the sheet is suctioned by the belt. There is provided a sheet conveying apparatus having a plurality of concave portions provided on a surface of the suction chamber which comes into contact with the belt at the time of sheet adsorption.

  According to the present invention, with a simple configuration in which a plurality of recesses are provided on the surface of the suction chamber that comes into contact with the belt, belt wear powder enters the plurality of recesses on the surface of the suction chamber, so that the surface of the suction chamber that comes into contact with the belt is provided. Of the belt abrasion powder on the sliding surface can be reduced, thereby preventing sticking and abrasion and suppressing the sliding resistance between the belt and the suction chamber over time.

1 is a perspective view illustrating a schematic configuration of an air-pick type sheet feeding device according to an embodiment of the present invention. FIG. 2 is a perspective view showing a sheet feeding unit included in the sheet feeding device of FIG. 1 upside down. FIG. 3 is a view of the sheet feeding unit in FIG. (A) is a diagram schematically showing a cross section of a main part of a conventional paper feeding unit, and (b) is a schematic cross section of a main part for explaining a problem of the conventional paper feeding unit of (a). FIG. FIG. 2A is a diagram schematically illustrating a cross section of a main part of the paper feeding unit according to the embodiment, and FIG. 2B is a diagram schematically illustrating a cross section of a main part explaining the operation of the paper feeding unit of FIG. is there. FIG. 3 is a plan view illustrating a shape of a minute uneven surface formed on the surface of the suction chamber according to the first embodiment. (A) is a graph illustrating the results of an experiment on the increase in the load of the drive motor over time due to the presence or absence of the minute uneven surface, and (b) is a graph illustrating the weight change of the suction belt during the experiment of (a). . FIG. 11 is a plan view showing a groove shape formed on the surface of the suction chamber according to the second embodiment. 5 is a graph illustrating a relationship between a static pressure in a suction chamber and a clearance of the sheet feeding unit according to the embodiment. FIG. 14 is a plan view illustrating a shape of a skew groove formed on the surface of the suction chamber according to the third embodiment. FIG. 14 is a plan view illustrating a formation range of a groove formed on a surface of a suction chamber according to a fourth embodiment. FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. FIG. 1 is a schematic configuration diagram of a sheet feeding device according to an embodiment.

  Hereinafter, embodiments of the present invention including examples will be described in detail with reference to the drawings. Throughout the embodiments, components (members and components) having the same function, shape, and the like will be described once unless there is a risk of confusion, and the description will be omitted by assigning the same reference numerals. For simplicity of the drawings and description, components that do not need to be specifically described in the drawings may be omitted without omission, even if they are components to be shown in the drawings. When a description is given with reference to constituent elements of a published patent publication or the like, the reference numerals are shown in parentheses to distinguish them from those of the embodiments and the like.

With reference to FIG. 1, a schematic configuration of an air-pick type sheet feeding device showing one embodiment of a sheet conveying device and a sheet feeding device of the present invention will be described. FIG. 1 is a perspective view illustrating a schematic configuration of an air-pick type sheet feeding device showing an embodiment of a sheet conveying device and a sheet feeding device according to the present invention.
As shown in FIG. 1, the air-pick type sheet feeding device 50 (hereinafter, simply referred to as “sheet feeding device 50”) includes a sheet feeding tray 10, a front blowing device 12, a pair of side blowing devices 14, a sheet feeding unit 20, and the like. Have. The paper feeding device 50 functions as a sheet feeding device according to the present invention.
In FIG. 1, the arrangement of the front air blower 12 and the pair of side air blowers 14 and the state of each air blow are hidden by the paper feed unit 20 so that they are difficult to see. The paper feeding unit 20 is intentionally shifted to the downstream side in the paper feeding direction X which is the feeding direction.

The paper feed tray 10 includes a sheet stacking table 11 which is a sheet stacking table for stacking a sheet bundle of sheets as an example of sheets. The paper loading table 11 is configured to be able to move up and down by a lifting mechanism having a motor as a drive source (not shown).
Further, air (hereinafter, also referred to as “air”) is blown to the paper feed tray 10 at an upper end portion of the sheet bundle SA (a downstream end portion in a sheet feeding direction or a sheet feeding direction X which is a sheet conveying direction). A side air blower 14 is provided for each of the front air blower 12 and the pair of side fences 13 and blows air to the upper side surface of the sheet bundle SA.

The front blower 12 has a floating nozzle (not shown) that guides air in a direction in which the sheet S or the sheet bundle SA floats, and guides air in a direction in which the uppermost floating sheet is separated from other sheets. Separating nozzles (not shown) are arranged, and the air blown from each nozzle is indicated by floating air (indicated by a thick white arrow below the front blower 12) and separated air (above the front blower 12). (Indicated by a thick white arrow). The side blowing device 14 is provided with a side floating nozzle (not shown) for guiding the air in a direction in which the sheet bundle SA is loosened and floated, and the air blown from the nozzle is supplied to the side air (each side blowing device 14). (Indicated by a thick white arrow erupting from).
As described above, the front air blower 12 and the side air blower 14 function as air blowing means for floating the end of the paper to the sheet S or the sheet bundle SA stacked and stacked on the sheet stacking table 11. . Further, the front blower 12 functions as a separating unit that separates the sheet bundle floated by the front blower 12 and the side blower 14 into individual sheets.

Above the paper feed tray 10, a paper feed unit 20 that adsorbs and feeds or conveys the paper P loaded on the paper loading table 11 is arranged. The paper supply unit 20 includes an endless suction belt 21 and a suction device 23 that are transport members.
The suction belt 21 is stretched over a pair of cross-linking rollers 22a and 22b (hereinafter, also referred to as “cross-linking”) that are arranged in parallel in the paper feeding direction X at an interval. Holes for suction and suction penetrating to the back surface side are formed over the entire area in the circumferential direction (see FIGS. 2 and 3 described later, and all the holes are omitted in FIG. 1).

  The suction device 23 is connected to and connected to a blower fan (not shown) (not shown) through an air duct 25 disposed inside the suction belt 21 between the pair of bridging rollers 22a and 22b. The air in the air duct 25 is sucked in the direction indicated by the thick white arrow by the exhaust of the blower fan, thereby generating a negative pressure below the upper suction belt 21. Acts to adsorb. As described above, the sheet feeding unit 20 functions as a holding unit or a sheet conveying device that holds and separates the floating sheet.

The detailed configuration and operation of the paper feed unit 20 provided in the paper feed device 50 of FIG. 1 will be described with reference to FIGS. FIG. 2 is a perspective view showing the sheet feeding unit 20 provided in the sheet feeding device 50 of FIG. 1 upside down, and FIG. 3 is a view of the sheet feeding unit 20 of FIG. 2 viewed from the direction of arrow A in FIG. FIG.
As shown in FIGS. 2 and 3, three sets of three suction belts 21a, 21b, and 21c are cross-linked to the cross-linking rollers 22a and 22b, and each of the suction belts 21a, 21b, and 21c is a suction belt. A plurality (many) of holes 21d are formed to penetrate the suction belt over the entire circumference. In FIGS. 2 and 3, the holes 21d are omitted from the suction belts 21a, 21b, and 21c located above the cross-linking rollers 22a and 22b for the sake of simplicity. When the suction belts 21a, 21b, 21c are described without distinction, they will be generically referred to as the suction belt 21 hereinafter.

  As shown in FIG. 2, a drive motor 27 for rotating the drive roller 26a and the suction belt 21 is connected to a drive shaft 26 of the bridge roller 22a via a drive force transmitting means such as a belt and a pulley. Have been. As the drive motor 27, for example, a stepping motor that rotates by pulse input is used. The bridging roller 22b is a driven roller that is driven to rotate via the suction belt 21, and is rotatably supported by the main frame of the sheet feeding unit via a shaft.

  Inside the bridging rollers 22a and 22b and the suction belt 21, a box-shaped suction chamber 24 having a hollow inside is disposed. As shown in FIG. 3, the suction chamber 24 has a plurality of openings 24 a (see FIG. 3) corresponding to the arrangement of the holes 21 d of the suction belt 21 so as to face the surface of the suction belt 21 on which the paper is to be suctioned. (Indicated by a broken line) is provided. Further, as shown in FIG. 2, the suction chamber 24 has an internal cavity communicating with one end of a duct 25, and the other end of the duct 25 communicates with a blower fan 28 schematically shown.

  The operation of the sheet feeding device 50 will be supplementarily described. When the blower fan 28 is driven to rotate, the air in the suction chamber 24 is exhausted through the duct 25, and the air pressure in the suction chamber 24 is reduced to a negative pressure. Air is sucked in through the hole 21d, and the uppermost sheet of the sheet bundle stacked below the suction belt 21 is suctioned to the suction belt 21.

  The sheet adsorbed on the suction belt 21 is rotated and driven by a drive motor 27 connected to a drive shaft 26 of the cross-linking roller 22a, so that the suction belt 21 rotates and runs in the sheet feeding direction X via the cross-linking roller 22a, The sheet S is conveyed toward an image forming apparatus or an image forming unit that is a sheet feeding destination.

With reference to FIG. 4, the configuration and problems of the conventional paper feeding unit will be described. FIG. 4A is a diagram schematically showing a cross section of a main part of the conventional paper feeding unit, and FIG. 4B is a main part for explaining a problem of the conventional paper feeding unit of FIG. It is a figure which shows the cross section of FIG. 4A and 4B, reference numeral 20X denotes a conventional paper feeding unit, and reference numeral 24X denotes a conventional suction chamber 24.
As shown in FIG. 4A, in the conventional paper feeding unit 20X, generally, there is no gap (clearance) between the lower surface 24b of the suction chamber 24X and the rear surface 21e of the suction belt 21. Was set to That is, at the time of non-sheet suction, in which the sheet is not sucked by not exhausting the air from the suction chamber 24X, there is no clearance between the front surface 24b of the suction chamber 24X and the back surface 21e of the suction belt, and the front surface 24b of the suction chamber 24X and the back surface 21e of the suction belt do not. Were set so as to always face each other. It should be noted that the non-sheet-sucking state represents a non-sheet-sucking state in which a sheet is not sucked.

A lower surface 24b of the suction chamber 24X of the conventional sheet feeding unit 20X has a sliding surface that slides on the back surface 21e of the suction belt 21 during sheet suction conveyance, which is a sheet suction conveyance for sucking and conveying a sheet. Therefore, it was usually formed on a smooth surface.
Therefore, when the air in the suction chamber 24X is sucked during the sheet suction conveyance, as shown in FIG. 4A, a suction force P that is a force for sucking the suction belt 21 is generated. When there is no clearance, the back surface 21e of the suction belt 21 is in close contact with the front surface 24b of the suction chamber 24X with the suction force P against the front surface 24b of the suction chamber 24X. 24b, the frictional force generated between the back surface 21e of the suction belt 21 and the front surface 24b of the suction chamber 24X, which is generated when the suction belt 21 is driven, is P.mu. Become. When the back surface 21e of the suction belt 21 comes into close contact with the suction chamber 24X with the suction force P against the front surface 24b of the suction chamber 24X, the tension T1 shown in FIG.

  When the paper is repeatedly fed in the paper feed unit 20X of FIG. 4A, the back surface 21e of the suction belt 21 comes into contact (close contact) with the surface 24b of the suction chamber 24X, and the surface 24b of the suction chamber 24X slides. As shown in FIG. 4 (b), the back surface 21e of the suction belt 21 is scraped due to the sliding resistance of the sliding surface, and the fine scrap 29 of the suction belt 21 (made of rubber abrasion powder) is formed. ) Adhere to the sliding surface 24b of the suction chamber 24X over time.

  When the main component of the suction belt 21 is rubber, shavings 29 adhered to the front surface 24b serving as the sliding surface of the suction chamber 24X are repeatedly rubbed between the back surface 21e of the suction belt 21 and the front surface 24b of the suction chamber 24X. As a result, the scrap 29 becomes tacky (adhesive wear) due to the influence of frictional heat generated when the suction belt 21 rotates, and a rubber film is formed on the surface 24b of the suction chamber 24X. When the sticky and worn rubber film is generated, the friction coefficient between the back surface 21e of the suction belt 21 and the front surface 24b of the suction chamber 24X when the suction belt 21 is driven is compared with the friction coefficient between the rubbers. Since μ ′ and μ <μ ′, the sliding resistance between the suction belt 21 and the suction chamber 24X increases, and the load on the drive motor 27 that drives the suction belt 21 via the bridging roller 22a increases. However, there is a problem that the motor loses synchronism due to a temporal change in load of the drive motor 27.

Next, a characteristic embodiment of the present invention which can solve the problem of the conventional paper feeding unit shown in FIG. 4 will be described with reference to FIGS.
FIG. 5A is a diagram schematically illustrating a cross section of a main part of the paper feeding unit according to the embodiment, and FIG. 5B is a cross section of a main part illustrating an operation of the paper feeding unit of FIG. It is a figure which shows typically.
The paper feeding unit 20 according to the present embodiment shown in FIG. 5 is different from the conventional paper feeding unit 20X shown in FIG. 4 only in that a suction chamber 24 is used instead of the suction chamber 24X. The suction chamber 24 has a plurality of concave / convex surfaces 30 as a plurality of recesses on the front surface 24b of the suction chamber 24 that comes into contact with the back surface 21e of the suction belt 21 when the paper exhausted from the suction chamber 24 is adsorbed as compared with the sheet feeding unit 20X. The point provided is mainly different.
In FIGS. 5A and 5B, a gap is provided intentionally so that the front surface 24b of the suction chamber 24 and the back surface 21e of the suction belt 21 are not in contact with each other. This is to clearly show the above-described characteristic configuration and operation of the surface 24b of the suction chamber 24 of the embodiment, and the surface 24b of the suction chamber 24 and the suction belt 21 are similar to the conventional suction chamber 24X shown in FIG. Is always in contact with the back surface 21e.

  As shown in FIG. 5A, the front surface 24b of the suction chamber 24 has a sliding surface between the back surface 21e of the suction belt 21 and the front surface 24b of the suction chamber 24 during paper suction. The minute uneven surface 30 is formed. The minute uneven surface 30 is formed such that the height difference of the minute uneven surface 30, which is the depth of the concave portion, is 40 μm or more.

  Due to the formation of the minute uneven surface 30 on the sliding surface of the surface 24b of the suction chamber 24, as shown in FIG. 5B, when the scrap 29 of the suction belt 21 is generated during the paper suction conveyance. Then, the shavings 29 enter the concave portions of the minute uneven surface 30. As a result, the scrap 29 does not intervene on the sliding surface between the back surface 21e of the suction belt 21 and the front surface 24b of the suction chamber 24, thereby suppressing the occurrence of the above-mentioned sticking and abrasion of the rubber. Since the friction coefficient μ with the motor 24 is maintained, an increase in the load on the drive motor can be suppressed, and the load can be reduced.

When the shavings 29 of the suction belt 21 are generated, the depth of the concave portion is 40 μm or more from the viewpoint of making it easier for the shavings 29 to enter the concave portion of the minute uneven surface 30 and the viewpoint of holding the shavings 29 by the concave portion. It is preferred that
Although the height difference of the minute uneven surface 30 is formed at 40 μm or more as described above, the surface 24 b of the suction chamber 24 that is in contact (close contact) with the back surface 21 e of the suction belt 21 as described in a second embodiment described later. The depth of the minute uneven surface 30 is preferably set to 1.25 mm or less from the viewpoint of avoiding double feeding caused by the influence of air leaking from a gap formed with the groove (hereinafter, also referred to as “clearance”).

(Example 1)
Embodiment 1 With reference to FIG. 6, a first embodiment in which minute concave and convex surfaces as a plurality of concave portions are formed on the surface of the suction chamber will be described. FIG. 6 is a plan view showing the shape of the minute uneven surface according to the first embodiment formed on the surface of the suction chamber.
The shape of the minute uneven surface 30 according to the first embodiment shown in FIG. 6 is such that a sandblasting process (fine) is performed on almost the entire surface 24b of the suction chamber 24 except for the plurality of openings 24a in contact with the back surface 21e of the suction belt 21. Fine irregularities are formed on the surface 24b, which is the sliding surface of the suction chamber 24 that slides on the suction belt 21, by forming a projection and depression on the surface by applying bead particles to the surface).
The sheet feeding unit (not shown) of the first embodiment is the same as the sheet feeding unit shown in FIG. 5 except that the method of forming the minute uneven surface 30 is clearly described as described above (the following examples 2 to 4 also). the same).

Strictly speaking, the micro uneven surface 30 in FIG. 6 is formed by the area of the front surface 24b of the suction chamber 24 facing / contacting the back surface 21e of the suction belts 21a, 21b, 21c shown in FIG. It is formed by performing the above-described surface treatment on a region between the suction belt 21b and the suction belt 21b and a region between the suction belt 21b and the suction belt 21c.
A region of the front surface 24b of the suction chamber 24 corresponding to a region between the suction belts 21a and 21b adjacent to each other and a region between the suction belts 21b and 21c faces the back surface 21e of the suction belt 21 but is in contact therewith. It is an area that has not been done. This is in consideration of eliminating the trouble of covering the above-mentioned portion with a cover or the like when performing the above-mentioned surface treatment processing. There is no problem in that it is possible to allow the margin 29 to enter the concave portion of the minute uneven surface 30 with a margin.

  As shown in FIG. 6, fine spherical or satin-like irregularities are formed on the surface 24b of the suction chamber 24 as minute irregularities 30, and shavings 29 of the suction belt enter the concaves of the minute irregularities (FIG. 5 (b)). )), The increase in the sliding resistance and the increase in the load on the drive motor can be suppressed, and the load torque on the drive motor can be reduced.

With reference to the graph of FIG. 7, a description will be given of the results of an experiment performed on the increase in the load of the drive motor 27 over time depending on the presence or absence of the minute uneven surface 30 of the suction chamber, and the weight change of the suction belts 21 a to 21 c at that time. FIG. 7A is a graph illustrating the result of an experiment on the increase in the load of the drive motor over time depending on the presence or absence of the minute uneven surface. FIG. 7B is a graph illustrating a change in weight of the suction belt during the experiment of FIG. 7A.
In the above experiment, the suction chamber 24X of the conventional example in which the surface 24b shown in FIG. 4 has no minute uneven surface (hereinafter referred to as “no unevenness”) and the minute uneven surface 30 described in the first embodiment of FIG. A comparative confirmation experiment is performed using a suction chamber 24 having an unevenness (hereinafter referred to as “unevenness”) (having a height difference of 40 μm between the unevenness). The experimental conditions other than the presence / absence of the minute uneven surface 30 of the suction chamber were the same. The suction belts 21a to 21c were made of ethylene propylene rubber (EPDM), and the suction chambers 24X and 24 were made of polyacetal. This was performed using a resin (POM).

In FIG. 7A, the horizontal axis indicates the number of passed sheets [k sheets (× 1000 sheets)], and the vertical axis indicates the load torque [Ncm] of the drive motor (in FIG. 7A, “motor load torque”). Are taking each one. From the experimental results in FIG. 7A, the suction belt is particularly easy to be scraped in the initial stage, and when there is no unevenness, scraps are generated by scraping the suction belt up to about 200k sheets, and the scraps adhere to the sliding surface of the suction chamber. As a result, the load torque of the drive motor continues to increase. Thereafter, the load torque tended to gradually decrease due to saturation of the scraping of the suction belt.
On the other hand, when there was unevenness, the load torque of the drive motor did not increase with time as compared with the case without unevenness, and the superiority of Example 1 with unevenness was recognized.

  The horizontal axis in FIG. 7B indicates the number of sheets passed [k sheets (× 1000 sheets)], and the vertical axis indicates the weight change amount [g] of the suction belt (in FIG. 7B, “weight change amount”). Are listed). According to the experimental results of FIG. 7B, when the suction chamber has irregularities, the amount of change in weight of the suction belt changes, but the experimental results of FIG. 7A show that there is no increase in the motor load torque. It was confirmed that the increase in the load torque was suppressed by the entry of shavings into the concave portions of the irregularities.

  As described above, according to the present embodiment and Example 1, the rubber abrasion powder is reduced by a simple configuration in which a plurality of concave portions and a plurality of minute concave and convex surfaces are provided on the surface of the suction chamber in contact with the suction belt. By entering the plurality of recesses on the surface of the suction chamber, it is possible to reduce the adhesion of the rubber wear powder to the sliding surface of the surface of the suction chamber that comes into contact with the belt. Thus, by preventing the rubber from sticking and abrasion and suppressing an increase in the sliding resistance between the suction belt and the suction chamber, the load fluctuation of the drive motor for driving the suction belt can be reduced over time, and the drive motor can be reduced. Step-out can be prevented beforehand.

(Example 2)
A second embodiment in which a plurality of minute grooves are formed as a plurality of recesses on the surface of the suction chamber will be described with reference to FIGS. FIG. 8 is a plan view showing a groove shape according to the second embodiment formed on the surface of the suction chamber. FIG. 9 is a graph illustrating the relationship between the static suction pressure and the gap according to the second embodiment.
In the second embodiment shown in FIG. 8, instead of the minute uneven surface 30 of the first embodiment shown in FIG. 6, a plurality of minute grooves 30a (hereinafter, also simply referred to as "grooves 30a") are formed as a plurality of concave portions. The main difference is that it is formed on the surface 24b of the H.24. In the plurality of grooves 30a, a concave portion is formed by engraving a linear groove 30a along the belt width direction Y orthogonal to the sheet feeding direction X. As described above, since the scraps of the suction belt enter the groove 30a, it is possible to suppress an increase in the sliding resistance and an increase in the load on the drive motor, and to reduce the load torque on the drive motor.
Strictly speaking, the groove 30a in FIG. 8 is formed in the area of the front surface 24b of the suction chamber 24 facing / contacting the back surface 21e of the suction belts 21a, 21b, 21c shown in FIG. The groove is formed by engraving the groove in the region between the belt 21b and the suction belt 21b and the suction belt 21c.

  However, when the groove is formed, if the depth of the groove exceeds 1.25 mm, the air leaking from the gap between the suction belt and the groove 30a (hereinafter, also referred to as “clearance”) becomes strong, and the paper adheres to the suction belt 21. At this time, since there is a possibility that a double feed that sucks the next sheet may occur, it is preferable to form the groove 30a with a depth of 1.25 mm or less.

Next, with reference to FIG. 9, Table 1 and Table 2, the grounds for preferably forming the groove 30a with a depth of 1.25 mm or less will be described. FIG. 9 is a graph showing the clearance [mm], which is the same as the depth of the groove 30a, on the horizontal axis and the static pressure [kPa] in the suction chamber on the vertical axis.
Regarding the surface density of the grooves 30a, which is the number of grooves per unit area, suction is performed by changing the clearance into five stages of 0.5 to 1.50 [mm] using a suction chamber in which a fixed number of grooves 30a are formed. The change in the static pressure [kPa] in the chamber was measured.

  In Table 1, the output of the measuring instrument represents the output [V] of the fan motor that drives the blower fan at a duty ratio (only described as “Duty” in Tables 1 and 2) of 40 to 100%. . In Table 2, the pressure conversion value represents a pressure [-kPa] corresponding to the output [V] of the fan motor that drives the blower fan at a duty ratio of 40 to 100%. In Tables 1 and 2, the duty ratio of 80% is the target value.

  From the above experimental results, it is possible to secure a substantially constant appropriate static pressure in the suction chamber up to a clearance of 0.5 to 1.25 mm, but if the clearance exceeds 1.25 mm, the suction chamber It was found that the internal static pressure dropped rapidly. Therefore, as shown in FIG. 9 and Tables 1 and 2, when forming the groove, if the depth of the groove exceeds 1.25 mm, the air leaking from the gap (clearance) between the suction belt and the groove 30a becomes strong, and It was found that it was not possible to secure a sufficient static pressure in the suction chamber. This means that when a sheet is attracted to the attraction belt 21, there is a possibility that a double feed may occur in which the next sheet is also attracted.

As described above, according to the second embodiment, the rubber has a simple configuration in which minute grooves formed by engraving grooves along the belt width direction Y orthogonal to the sheet feeding direction X are provided as a plurality of concave portions. Since the abrasion powder enters the plurality of linear small grooves on the suction chamber surface, it is possible to reduce the adhesion of the rubber abrasion powder to the sliding surface on the surface of the suction chamber that comes into contact with the belt. Thus, by preventing the rubber from sticking and abrasion and suppressing an increase in the sliding resistance between the suction belt and the suction chamber, the load fluctuation of the drive motor for driving the suction belt can be reduced over time, and the drive motor can be reduced. Step-out can be prevented beforehand.
Further, since the groove 30a is formed to have a depth of 1.25 mm or less, air leaking from a gap (clearance) between the suction belt and the groove 30a can be prevented, and double feed can be prevented. To summarize the above, it is desirable to form the groove 30a with a depth and width of 1.25 mm or less. That is, it is preferable that the depth of the groove 30a is equal to or greater than the depth of the minute uneven surface 30 of the first embodiment, that is, 40 μm or more and 1.25 mm or less.

(Example 3)
Third Embodiment With reference to FIG. 10, a third embodiment in which a plurality of minute diagonal grooves are formed as a plurality of concave portions on the surface of the suction chamber will be described. FIG. 10 is a plan view showing a fine oblique groove shape according to the third embodiment formed on the surface of the suction chamber.
In the third embodiment shown in FIG. 8, instead of the groove 30a of the second embodiment shown in FIG. 8, a plurality of linear skewing grooves 30b (hereinafter, also referred to simply as "slanting grooves 30b") as a plurality of concave portions. ) Is formed on the surface 24b of the suction chamber 24. The plurality of skew grooves 30b are formed as skew grooves 30b skewed in the sheet feeding direction X so as not to have a continuous convex plane in the sheet feeding direction X.

  For example, when a plurality of linear grooves are arranged in parallel with the sheet feeding direction X of the suction belt 21, the convex surface of the suction chamber is formed continuously in the same direction as the sheet feeding direction X, so that the convex portion The scraps of the suction belt adhere to the surface, and the effects of increasing the sliding resistance and suppressing the load torque, which are problems of the present invention, are lost. Therefore, the skewed groove 30b formed on the surface 24b of the suction chamber 24 is skewed with respect to the sheet feeding direction X as shown in FIG.

  As described above, according to the third embodiment, grooves are formed along the direction oblique to the sheet conveyance direction X as a plurality of recesses so as not to have a continuous convex plane in the sheet conveyance direction X. With the simple configuration of providing a plurality of skewed grooves formed as described above, the rubber abrasion powder enters the plurality of skewed grooves on the surface of the suction chamber, so that the surface of the suction chamber in contact with the belt slides on the sliding surface. Adhesion of rubber abrasion powder can be reduced. Thus, by preventing the rubber from sticking and abrasion and suppressing an increase in the sliding resistance between the suction belt and the suction chamber, the load fluctuation of the drive motor for driving the suction belt can be reduced over time, and the drive motor can be reduced. Step-out can be prevented beforehand.

(Example 4)
Referring to FIG. 11, a fourth embodiment in which the formation range of a plurality of minute grooves on the surface of the suction chamber is made equal to the width of the suction belt will be described. FIG. 11 is a plan view illustrating a formation range of a minute groove according to the fourth embodiment formed on the surface of the suction chamber.
First, the minute groove 30c according to the fourth embodiment shown in FIG. 11 is formed only on the surface 24b of the suction chamber 24 that comes into contact with the suction belt, as compared with the groove 30a according to the second embodiment shown in FIG. Is different. That is, the formation range of the groove 30c is the same as the width region of the corresponding suction belt. Specifically, the groove 30c is formed between the suction belt 21a and the suction belt 21b in the belt width direction Y adjacent to each other of the suction belts 21a, 21b, and 21c shown in FIG. It is not formed in the region between them. Thus, it is desirable that the formation range of the groove 30c be equal to or less than the width of the suction belt.

Second, the groove 30c according to the fourth embodiment has a depth in the belt width direction Y orthogonal to the sheet conveying direction X as compared with the groove 30a according to the second embodiment illustrated in FIG. The difference is that both ends of the belt (parts A and A in FIG. 11) are 0 mm, and are formed deeper toward the center part (part B shown in FIG. 11) of the suction belt in the belt width direction Y. This makes it possible to reduce air leaking from the plurality of grooves 30c as compared with the groove 30a according to the second embodiment shown in FIG.
Specifically, the depth of the groove 30c is such that the depth of both ends of the suction belt indicated by the point A in FIG. 11 is 0 mm, and the depth of the groove is increased toward the center B point of the suction belt. The air leakage described in the second embodiment in FIG. 8 can be prevented, and the occurrence of double feeding can be prevented.

As described above, according to the fourth embodiment, the rubber wear powder is reduced by a simple configuration in which a minute groove formed by engraving a linear groove in the belt width direction Y orthogonal to the sheet conveyance direction X is provided. By entering the plurality of minute grooves on the surface of the suction chamber, it is possible to reduce the adhesion of the rubber wear powder to the sliding surface of the surface of the suction chamber that comes into contact with the suction belt. Thus, by preventing the rubber from sticking and abrasion and suppressing an increase in the sliding resistance between the suction belt and the suction chamber, the load fluctuation of the drive motor for driving the suction belt can be reduced over time, and the drive motor can be reduced. Step-out can be prevented beforehand.
Further, the depth of the minute groove 30c is 0 mm at both ends of the suction belt in the belt width direction Y orthogonal to the sheet conveying direction X, and is formed deeper toward the center of the suction belt in the belt width direction Y. Thus, it is possible to prevent air leakage described in the second embodiment shown in FIG.

  Although the shape of the surface 24b of the suction chamber 24 in the first to fourth embodiments is a flat plate, the present invention is not limited to this. For example, a surface curved in a direction perpendicular to the sheet conveying direction as disclosed in Patent Document 1 described above. Needless to say, a plurality of recesses according to the present invention may be formed to obtain the above-described effect.

The overall configuration and operation of the image forming apparatus according to the embodiment will be described with reference to FIG. FIG. 12 is a schematic configuration diagram of the image forming apparatus according to the embodiment.
As shown in FIG. 12, an image forming apparatus 100 as an image forming unit according to the present embodiment has a printer to which the sheet conveying device and / or the sheet feeding device of the present embodiment can be applied, and an equivalent image forming function. 1 is an example of an image forming apparatus such as a copying machine having the same. The image forming apparatus 100 is a full-color printer using four color toners of yellow (Y), cyan (C), magenta (M), and black (K) and a full-color copying machine having an equivalent image forming function.

  Four image forming units 101Y, 101M, 101C, and 101K, each of which forms an image with each color toner, are arranged side by side in the upper part of the apparatus main body. Since the configuration and operation of each of the image forming units 101Y, 101M, 101C, and 101K are substantially the same, here, the image forming units will be described by omitting the symbols (Y, M, C, and K) indicating the colors. . In the image forming unit 101, a charger 103, a developing device 104, a cleaning device 105, and the like are arranged around a photosensitive drum 102 as an image carrier. Further, an exposure unit 107 is disposed above the photosensitive drum 102.

  Below the four image forming units 101Y, 101M, 101C, and 101K, an intermediate transfer belt 108 wound around a plurality of support rollers is arranged. The intermediate transfer belt 108 is driven to run in the direction of arrow A1 by rotating one of the support rollers by a driving unit (not shown). A transfer roller 106 as a primary transfer unit is disposed so as to face the photosensitive drum 102 of each image forming unit with the intermediate transfer belt 108 interposed therebetween.

  In each image forming unit 101, the photoconductor drum 102 is rotated counterclockwise in the drawing, and the surface of the photoconductor is uniformly charged to a predetermined polarity by the charger 103. Next, the charged surface is irradiated with a light-modulated laser beam emitted from the exposure means 107, whereby an electrostatic latent image is formed on the photosensitive drum 102. The electrostatic latent image is developed with toner provided from the developing device 104, and is visualized as a toner image. The yellow, cyan, magenta, and black toner images formed by the image forming units are sequentially superimposed and transferred onto the intermediate transfer belt 108.

  On the other hand, a sheet feeding unit 114 having sheet feeding trays 114a and 114b is provided at a lower portion of the apparatus main body. The sheet feeding unit 114 or a sheet feeding device 200 to be described later attached to the image forming apparatus 100 is provided with a sheet feeding unit 114. For example, transfer paper is fed as a sheet-like recording medium. The fed transfer paper is conveyed toward the registration roller 111 as indicated by an arrow B1. The transfer paper abutted against the registration roller 111 and temporarily stopped is sent out from the registration roller 111 at a timing with the toner image on the intermediate transfer belt 108, and the secondary transfer roller 109 and the intermediate transfer belt 108 come into contact with each other. It is sent to the secondary transfer section. A voltage having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roller 109, whereby the superposed toner image (full color image) on the intermediate transfer belt 108 is transferred onto the transfer paper. The transfer paper after the transfer of the toner image is transported to the fixing device 113 by the transport belt 112, and the toner is fixed on the transfer paper by the fixing device 113 by heat and pressure. The transfer paper after the toner image is fixed is discharged out of the apparatus as indicated by an arrow C and discharged onto a discharge tray (not shown).

  In the case of single-sided printing for backside discharge (face-down discharge), the paper is discharged outside the apparatus via the paper reversing unit 115 as shown by the arrow C, so that the front and back of the paper are reversed. In the case of double-sided printing, the sheet after fixing is fed again from the re-feeding path 117 to the registration roller 111 via the double-sided reversing section 116, and the toner image is transferred from the intermediate transfer belt 108 to the back side of the sheet. The sheet after the transfer of the toner image is fixed by the fixing device 113, and is transferred from the fixing device 113 to the outside of the machine as indicated by an arrow C as in the case of single-sided printing, or as indicated by an arrow C via the sheet reversing unit 115. The sheet is discharged and discharged onto a discharge tray (not shown). Switching claws 118 and 119 for switching the paper transport direction are appropriately arranged.

In the case of monochrome printing, the image forming apparatus 100 of the present embodiment forms a toner image using only the black (K) image forming unit 101K, and transfers the toner image onto transfer paper via the intermediate transfer belt 108. I do. The handling of the paper after fixing the toner image is the same as in the case of full-color printing.
A toner bottle setting unit 120 is provided on the upper surface of the apparatus main body to set toner bottles 121 for each color containing toner to be supplied to the developing device 104 of each image forming unit. An operation unit 124 having a display unit 122 and an operation panel 123 is also provided on the upper surface of the apparatus main body. Further, on the right side in the drawing of the apparatus main body, there is provided a sheet carrying-in section D from a sheet feeding device (see FIG. 13) described later. In the sheet carry-in section D, an opening 125 for receiving a sheet and a conveying means 126 for conveying the sheet are provided.

With reference to FIG. 13, a schematic configuration and operation of a sheet feeding device as a sheet feeding device of the present embodiment will be described. FIG. 13 is a diagram illustrating a schematic configuration and operation of the sheet feeding device according to the present embodiment.
As shown in FIG. 13, the sheet feeding device 200 of the present embodiment is an example of a sheet feeding device, and is detachably provided on a side surface of the apparatus main body of the image forming apparatus 100 shown in FIG. The paper feeding device 200 includes two upper and lower paper feeding trays 10 similar to those shown in FIG. Above each paper feed tray 10, a paper feed unit 20 that separates and feeds the paper S or a bundle of paper stacked on the paper feed tray 10 is arranged.

The paper feed unit 20 includes a suction belt 21 as a transport member and a suction device 23. Each paper feed tray 10 includes a paper loading table 11 on which a bundle of paper S and a bundle of paper are loaded. In the present embodiment, each paper feed tray can store up to about 2500 sheets. Further, each paper feed tray 10 is provided with a paper detection sensor 15 for controlling the elevation of the paper loading table 11.
The sheets stacked on the lower paper feed tray 10 are conveyed to the apparatus main body of the image forming apparatus 100 through the lower conveyance path 16 by the pair of exit rollers 80. The paper stacked on the upper paper feed tray 10 passes through the upper transport 17 and is transported to the apparatus main body of the image forming apparatus 100 by the exit roller pair 80.

  Not limited to the above-described configuration example, the image forming apparatus 100 in FIG. 12 and the sheet feeding apparatus 200 in FIG. 13 connected to the sheet carry-in section D may constitute a so-called image forming system. Further, instead of the sheet feeding unit 114 disposed in the apparatus main body of the image forming apparatus 100 in FIG. 12, an image forming apparatus in which the sheet feeding apparatus 200 in FIG. 13 is arranged may be used.

  Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and unless otherwise specified in the above description, the present invention described in the claims Various modifications and changes are possible within the scope of the spirit of the present invention. For example, it may be a combination of the technical matters described in the above embodiments and examples as appropriate.

  The present invention can also be applied to a device that conveys other than paper as long as it is a sheet conveying device that conveys the above-described sheet medium (also simply referred to as “sheet”). Examples of sheets include metal sheets such as coated paper, label paper, OHP sheets, plastic films, cloths, and copper foils, as well as paper, prepregs (sheet-like materials in which carbon fibers are pre-impregnated with resin). ), Etc., and include all transportable objects.

  Further, the image forming apparatus to which the present invention is applied may be an image forming apparatus having a sheet conveying device and / or a sheet feeding device and having an image forming unit for forming an image on a sheet. The image forming apparatus is not limited to the electrophotographic image forming apparatus shown in FIG. That is, the image forming apparatus includes an image forming apparatus including an image forming unit that forms an image on a sheet by an ink jet method, and an image forming unit that performs printing while wrapping a stencil master (stencil paper) around a plate cylinder and supplying ink. An image forming apparatus including a stencil printing apparatus or the like may be used.

  The effects described as appropriate in the embodiments of the present invention merely enumerate the most preferable effects resulting from the present invention, and the effects according to the present invention are limited to those described in the embodiments of the present invention. Not something.

10 paper feed tray 11 paper loading table (sheet loading table)
12 Front blower 13 Side fence 14 Side blower 15 Paper detection sensor (sheet detection means)
20 Paper feed unit (an example of a sheet conveying device)
21 Suction belt (example of belt)
21d Hole of suction belt 21e Back surface of suction belt 22a, 22b Cross-linking roller (an example of a roller pair)
Reference Signs List 23 suction device 24 suction chamber 24a opening of suction chamber 24b surface of suction chamber 25 air duct 26 drive shaft 27 drive motor 28 blower fan (an example of a fan)
29 Shavings 30 Micro uneven surface (an example of a concave portion)
30a, 30c Groove 30b Slant groove (an example of groove)
50,200 paper feeder (an example of a sheet feeder)
100 Image forming apparatus S paper (an example of a sheet)
SA Paper Bundle (Example of Sheet Bundle)
X Paper feeding direction (an example of sheet conveyance direction and sheet feeding direction)
Y belt width direction

JP 2013091549 A

Claims (12)

A roller pair arranged at intervals in the sheet conveying direction,
A belt spanned over the roller pair and having a plurality of holes,
A suction chamber disposed between the roller pair, the suction chamber having an opening on a surface on which the sheet is adsorbed;
A fan that exhausts air from the suction chamber,
A sheet transport device, wherein a plurality of concave portions are provided on a surface of the suction chamber which comes into contact with the belt when the sheet is sucked by the belt. The sheet conveying device according to claim 1,
The depth of the plurality of recesses is 40 μm or more, the sheet conveying device. The sheet conveying device according to claim 1, wherein
The sheet conveying device according to claim 1, wherein the plurality of recesses are formed by engraving a groove in a surface of the suction chamber. The sheet conveying device according to claim 3,
The sheet conveying device according to claim 1, wherein the groove has a depth of 1.25 mm or less. The sheet conveying device according to claim 3, wherein
The sheet conveying device, wherein the groove does not have a continuous convex surface in the sheet conveying direction. The sheet conveying device according to claim 3, wherein
The sheet conveying device according to claim 1, wherein the groove is formed only on a surface of the suction chamber that contacts the belt. The sheet conveying device according to claim 6,
The sheet is characterized in that the depth of the groove is 0 mm at both ends of the belt in a belt width direction orthogonal to the sheet conveyance direction, and is formed deeper toward a central portion of the belt in the belt width direction. Transport device. The sheet conveyance device according to any one of claims 1 to 7,
The depth of the plurality of recesses or the depth and width of the groove is set to 1.25 mm or less. The sheet conveyance device according to any one of claims 1 to 8,
The sheet conveying device, wherein the belt is formed of a material including rubber. The sheet conveyance device according to any one of claims 1 to 9,
A sheet conveying device comprising a drive motor for driving the roller pair. Air ejection means for floating the end of the air ejection sheet on the stacked sheets,
Holding means for holding and separating the floated sheet,
Conveying means for conveying the held sheet, and a sheet feeding apparatus comprising:
A sheet feeding device using the sheet conveying device according to any one of claims 1 to 10 as the conveying unit.   An image forming apparatus comprising the sheet conveying device according to claim 1 and / or the sheet feeding device according to claim 11.

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