Patent Application
20130341852
This patent application is based on and claims priority pursuant to 35 U.S.C. ยง119 to Japanese Patent Application No. 2012-141201, filed on Jun. 22, 2012 in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.
1. Technical Field
The present invention relates to a sheet conveying device provided in a sheet conveying system, an image reading device including the sheet conveying system, and an image forming apparatus including the sheet conveying system or the like. In particular, the present invention relates to a skew correcting device employed in one of the sheet conveying system, the image reading device, and the image forming apparatus or the like suitable for correcting skew of a thin sheet.
2. Related Art
In various types of image forming apparatuses, such as copiers, printers, facsimiles etc., and an image reading device, such as a scanner, etc., an image formation unit and/or an image reading unit are installed in the apparatus and device. In such an apparatus and device, by conveying a sheet, such as a plain paper sheet, etc., through the image formation unit, a desired image is formed on the sheet. Similarly, by conveying a sheet as an original document with recorded image information thereon through the image reading unit in such a device, the image information on the sheet is optically read.
In the conventional image forming apparatus and image reading device, to properly form an image or read the image information, skew of the sheet is corrected just before respective positions of the image reading unit and the image formation unit in a sheet conveyance direction to adjust a posture and a position of the sheet.
As a sheet conveying device that corrects the skew of the sheet, a roller nip collision system is known, in which a leading end of a sheet collides with a pair of nip forming rollers that stop rotation to bend the sheet and cause the leading end to fit along a roller nip formed between the pair of nip forming rollers by its elasticity.
Otherwise, a gate collision system is provided to correct the skew of the sheet. Specifically, a gate unit capable of entering or evacuating from a sheet conveyance path is provided to stop the sheet and cause the leading end thereof to fit along a gate member. The gate member evacuates from the sheet conveyance path after fitting of the leading end and thereby correcting the skew of the sheet.
However, in the roller nip collision system, such sheet skew correction performance depends on the bending of the sheet. In addition, the number of rollers installed and the spacing of the rollers to form the bending the sheet are limited by the maximum sheet width that the image forming apparatus can handle.
By contrast, in the gate collision system, when the leading end of the sheet collides with a sheet striking member (e.g. the gate), since it is sandwiched, and accordingly restricted at the nip formed between the pair of opposed conveyance rollers, the sheet rarely rotates on a horizontal plane to correct its skew. Accordingly, a degree of freedom to correct a position of the leading end of the sheet is relatively low, and accordingly, a small amount of the skew of the sheet can be corrected. As a result, an image is either diagonally formed or read resulting in inaccurate recording or reading.
Then, in the past, various sheet skew correction technologies are proposed as discussed, for example, in Japanese Patent Application Publication Nos. JP-2002-265100-A, JP-2002-128326-A, and JP-H08-081089-A or the like.
For example, JP-2002-265100-A discloses a technology, in which a pair of roller pieces is disposed at a widthwise center of a sheet to bend the sheet while reducing restriction force applied to the sheet and improving a skew correction function during a skew correction process, thereby upgrading recording accuracy.
Further, JP-2002-128326-A and JP-H08-081089-A also disclose technologies, in which a spherical roller is employed to bend the sheet while further reducing the restriction force applied to the sheet, thereby preventing stains and wrinkles possibly generated in the sheet.
However, with such conventional skew correction technologies, an especially thin sheet having a thickness of about 55 gsm (gram per square meter: g/m2) wrinkles at its leading end during a skew correction process.
That is, with the gate collision system of JP-2002-128326-A or the like as shown in
Similarly, with the system of JP-H08-081089-A shown in
Accordingly, the present invention provides a novel sheet conveying device that includes a sheet conveying guide disposed on a portion of a sheet conveyance path to guide a sheet; a pair of upstream sheet conveying rollers disposed upstream in the sheet conveyance path in a sheet conveyance direction; and a pair of downstream sheet conveying rollers disposed downstream of the pair of upstream side sheet conveying rollers in the sheet conveyance direction. A gate unit is located adjacent to the pair of downstream sheet conveying rollers and includes at least two striking faces divided perpendicular to the sheet conveyance direction. The gate unit is enabled to enter and evacuate from the sheet conveyance path. A skew correction control mechanism is provided to correct skew by bringing the gate unit to the sheet conveyance path to cause the striking face to collide with a leading end of the sheet coming with skew while rotating the pair of upstream sheet conveying rollers. At least one roller is included in one of the pair of upstream sheet conveying rollers and is disposed in the vicinity of a center of the sheet conveyance path. A width W of the at least one roller in its widthwise direction is smaller than a widthwise interval L between the at least two striking faces of the gate unit (i.e., W<L).
In another aspect of the present invention, an image forming apparatus employs an image formation unit and a sheet conveying device that includes a sheet conveying guide disposed on a portion of a sheet conveyance path to guide a sheet; a pair of upstream sheet conveying rollers disposed upstream in the sheet conveyance path in a sheet conveyance direction; and a pair of downstream sheet conveying rollers disposed downstream of the pair of upstream side sheet conveying rollers in the sheet conveyance direction. A gate unit is located adjacent to the pair of downstream sheet conveying rollers and includes at least two striking faces divided perpendicular to the sheet conveyance direction. The gate unit is enabled to enter and evacuate from the sheet conveyance path. A skew correction control mechanism is provided to correct skew by bringing the gate unit to the sheet conveyance path to cause the striking face to collide with a leading end of the sheet coming with skew while rotating the pair of upstream sheet conveying rollers. At least one roller is included in one of the pair of upstream sheet conveying rollers and is disposed in the vicinity of a center of the sheet conveyance path. A width W of the at least one roller in its widthwise direction is smaller than a widthwise interval L between the at least two striking faces of the gate members (i.e., W<L).
In yet another aspect of the present invention, an image reading device employs an original document conveying device. The original document conveying device includes an original document conveying guide disposed in an original document conveying path to guide original document; a pair of upstream original document conveying rollers disposed upstream of the original document conveying guide in an original document conveying direction in the original document conveying path; and a pair of downstream original document conveying rollers disposed downstream of the pair of upstream side original document conveying rollers in the original document conveying direction. A gate unit is located adjacent to the pair of downstream original document conveying rollers and includes multiple striking faces divided perpendicular to the original document conveying direction. The gate unit is enabled to enter and evacuate from the original document conveying path. A skew correction control mechanism is provided to connect skew by bringing the gate unit into the original document conveying path to cause the striking face to collide with a leading end of the original document coming with the skew while rotating the pair of upstream original document conveying rollers. More than one roller is included in one of the pair of upstream original document conveying rollers and is disposed in the vicinity of a widthwise center of the original document conveying path. A width W of the roller in its widthwise direction is smaller than a widthwise interval L between the multiple striking faces of the gate unit (i.e., W<L).
A more complete appreciation of the present invention and many of the attendant advantages thereof will be more readily obtained as substantially the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views thereof and in particular to
The sheet conveying device according to one embodiment of the present invention is disposed in a sheet conveyance path that leads a sheet 4 in a direction as shown by arrow X in
As shown in
The gate unit 12 is divided into a pair of gate members 12a and 12b as arranged in a direction perpendicular to the sheet conveyance direction X in this embodiment as shown in
In the first embodiment, a pair of striking faces 14 and 14 of the pair of gate members 12a and 12b is located downstream of a nip of the pair of downstream sheet conveying rollers 11 as shown in
In the first embodiment, a pair of striking faces 14 and 14 of the pair of gate members 12a and 12b is located downstream of a nip of the pair of downstream sheet conveying rollers 11 as shown in
Although a swingable gate evacuating member 15 is employed as a gate evacuating mechanism in this embodiment, the pair of gate members 12a and 12b can be moved up and down from the sheet conveyance path 17 to enable the pair of striking faces 14 and 14 thereof to either enter or evacuate from the sheet conveyance path 17.
In either case, as in this embodiment, when the pair of striking faces 14 and 14 of the pair of gate members 12a and 12b is located downstream of the nip of the pair of downstream sheet conveying rollers 11, the rollers 11b and 11a collectively constituting the pair of downstream sheet conveying rollers 11 are enabled to either engage or disengage from each other.
As shown in
Each of the pair of gate members 12a and 12b is fixed to a periphery of the gate moving roller 18. The gate moving roller 18 is coaxially located on a concentric circle with a lower side roller 11a of the pair of downstream sheet conveying rollers. Thus, when the gate moving roller 18 rotates by a given angle, the pair of striking faces 14 and 14 of the pair of gate members 12a and 12b can either enter or evacuate from the sheet conveyance path 17.
When the pair of striking faces 14 and 14 of the pair of gate members 12a and 12b is located upstream of the nip of the pair of downstream sheet conveying rollers in the sheet conveyance direction X as in this embodiment, the pair of roller pieces 11a and 11b constituting the pair of downstream sheet conveying rollers 11 may be substantially frequently pressed against each other.
In such a situation, as shown in
Further, the widthwise interval L between the striking faces 14 and 14 of the pair of gate members 12a and 12b is set smaller than a lateral width H of a minimum usage sheet 4 to meet the inequality (H>L) in order to enable the sheet 4 to collide with both of the striking faces 14 and 14 even when the maximum skew of the sheet 4 occurs therein. That is, the relation H>L>W is established as a whole.
As shown in
A pair of bent or curved sheet bending sections 21a and 21b is provided in the upper and lower guide plates 20a and 20b, respectively, just before the pair of gate members 12a and 12b in the sheet conveyance direction X to bend the sheet 4 in a loop forming direction.
A blower type fan (i.e., a blower) 22 is installed below the sheet bending section 21a of the lower guide plate 20a while facing a lower side of the sheet 4 conveyed thereto. Further, an optical sheet sensor 23, for example, is disposed slightly upstream of the pair of gate members 12a and 12b, preferably at a widthwise center of the sheet 4 coming close to the gate members 12 to detect a leading end of the sheet 4 and turns on/off the blower 22.
Now, an exemplary function of the sheet conveying device is described herein below. Specifically, as shown in
By contrast, in the second embodiment, the pair of downstream sheet conveying rollers 11 keeps contacting each other with pressure as shown in
Accordingly, the sheet 4 sandwiched between the pair of upstream sheet conveying rollers 10 is conveyed toward the pair of downstream sheet conveying rollers 11 across the sheet conveyance path 17 formed between the upper and lower guide plates 20a and 20b.
When the sheet sensor 23 detects the leading end of the sheet 4 and outputs a detection signal when it comes close to the pair of guide plates 20a and 20b of the sheet bending divisions 21a and 21b. Subsequently, a control unit (not shown) outputs a driving signal based on the detection signal and drives the blower 22. In this example, the sheet sensor 23 is disposed downstream of an air blowing section of the blower 22 in the sheet conveyance direction as shown in
The blower 22 blows air 24 toward the sheet bending section 21a of the lower guide plate 20a. Although not shown in the drawing, multiple numbers of slender air blowing slits or pores are formed being extended in the sheet conveyance direction X in the sheet bending section 21a. Accordingly, the sheet 4 can be conveyed fitting the sheet bending section 21b of the upper guide plate 20b as shown in
Further, the blower 22 is preferably turned off when the leading end of the sheet 4 is expected to engage with the pair of striking faces 14 and 14. Specifically, a time period from when the leading end of the sheet 4 with maximum sheet skew is detected by the sheet sensor 23 to when it hits the pair of striking faces 14 and 14 is sought beforehand and the blower stops its operation at the time, sheet skew can be smoothly corrected.
In addition, arrangement of these blower 22 and sheet sensor 23 is not limited to that as described above. Specifically, the blower can be turned on before the sheet sensor 23 detects the sheet 4 conveyed thereto and is turned off timely thereafter (e.g. a time when the leading end of the sheet 4 is expected to engage with the pair of striking faces 14 and 14).
In a state shown in
As shown in
By contrast, as shown in
As described earlier, the pair of upstream sheet conveying rollers 10 with a single roller 19 on a roller shaft is utilized in first embodiment. By contrast, in this embodiment, the pair of upstream sheet conveying rollers 10 includes a pair of roller pieces 19a and 19b on its roller shaft adjacent to the center of the sheet conveyance path 13. Further, also in this modification, a total width W of the pair of roller pieces 19a and 19b of the pair of upstream sheet conveying rollers 10 is set smaller than the widthwise interval L of the pair of gate members 12a and 12b (i.e., W<L).
Further, as shown in
Specifically, in the first embodiment of the present invention, the pair of gate members 12a and 12b are arranged perpendicular to the sheet conveyance direction X. By contrast, according to this embodiment, four gate members 12a, 12b, 12c, and 12d are located perpendicular to the sheet conveyance direction X, and a width W of a roller included in one of the pair of upstream sheet conveying rollers 10 in its axial direction is set smaller than the widthwise interval L between the gate members 12b and 12c (i.e., W<L) through which the center line 13 of the sheet conveyance path is extended.
As in the above-described embodiment, when presence of the coming sheet 4 is detected by the sheet sensor 23 disposed adjacent to the blower 22 and the blower 22 is controlled to be turned on/off based thereon, the blower 22 can effectively operate
Further, the leading end of the sheet 4 can fit the sheet bending section 21a in the lower guide plate 20a using a suction type blower 22 and pressing the sheet 4 against the lower guide plate 20a with suction force. Further, the position of the blower is not limited to the above-described location, and may be a side of the sheet bending unit 21b of the upper guide plate, for example.
Although the image forming apparatus with the sheet conveying device is described with reference to
Specifically, as shown there, an exemplary configuration of an image reading device 400 including an original document conveying unit 43 is provided. The original document conveying unit 43 includes the similar configuration to one of the sheet conveying devices 43 as employed in the above-described various embodiments, respectively. Specifically, in the drawing, a reference number 40 denotes a scanner unit equipped with a CCD (Charge Coupled Device) or the like, which optically reads an image described in an original document and converts and generates a digital signal based on a reading result. An original document loading tray 41 is provided to load the multiple original documents 42 thereon. An original document conveying unit 43 is provided and includes the similar configuration and function to that of the sheet conveying device 32 as employed in the above-described various embodiments. An original document reading section 44 is located downstream of the original document conveying unit 43, in which the image of the original document is optically read. An original document receiving tray 45 is also provided located downstream of the original document reading section 44 to receive the original documents ejected from the original document reading section 44 after optical reading thereof.
Thus, a posture and a feeding direction of the original document 42 with the skew are corrected in the original document conveying unit 43. As a result, the image in the original document is precisely read in the original document reading section 44. The original document is then ejected from the original document reading section 44 onto the original document receiving tray 45.
Hence, as described heretofore, according to one aspect of the present invention, an exemplary sheet conveying device can easily complete skew correction while reducing occurrence of wrinkles even in a thin sheet. Because, the exemplary sheet conveying device includes a sheet conveying guide disposed on a portion of a sheet conveyance path to guide a sheet, a pair of upstream sheet conveying rollers disposed upstream in the sheet conveyance path in a sheet conveyance direction, and a pair of downstream sheet conveying rollers disposed downstream of the pair of upstream side sheet conveying rollers in the sheet conveyance direction. A gate unit is located adjacent to the pair of downstream sheet conveying rollers and includes at least two striking faces divided perpendicular to the sheet conveyance direction. The gate unit is enabled to enter and evacuate from the sheet conveyance path. A skew correction control mechanism is provided to correct skew by bringing the gate unit into the sheet conveyance path to cause the striking face to collide with a leading end of the sheet coming with skew while rotating the pair of upstream sheet conveying rollers. At least one roller is included in one of the pair of upstream sheet conveying rollers and is disposed in the vicinity of a center of the sheet conveyance path. A width W of the at least one roller in its widthwise direction is smaller than a widthwise interval L between the at least two striking faces of the gate unit (i.e., W<L).
According to another aspect of the present invention, a sheet bending section is formed in the sheet conveying guide adjacent to the gate unit to bend the sheet in a loop forming direction. The sheet conveying guide is disposed between the gate unit and the pair of upstream sheet conveying rollers. In yet another aspect of the present invention, a blower is provided to blow air toward the sheet to fit a portion of the sheet into the sheet bending section, the blower facing one side of the sheet adjacent to the sheet bending section. Further, according to yet another aspect of the present invention, a vacuum to vacuum air to fit a portion of the sheet into the sheet bending section, the vacuum facing one side of the sheet adjacent to the sheet bending section. According to yet another aspect of the present invention, the pair of downstream sheet conveying rollers includes upper and lower rollers capable of engaging and disengaging with each other. The gate unit is disposed downstream of the pair of the downstream sheet conveying rollers in the sheet conveyance direction, and the upper and lower rollers separate from the other, and the striking face of the gate unit is disposed in the sheet conveyance path when sheet skew is corrected. According to yet another aspect of the present invention, upper and lower rollers of the pair of downstream sheet conveying rollers substantially frequently contact each other, and a striking face of the gate member is disposed in the sheet conveyance path upstream of a nip of the pair of downstream sheet conveying rollers in the sheet conveyance direction when the sheet skew is corrected. According to yet another aspect of the present invention, the pair of upstream sheet conveying rollers have at least one roller located substantially at a center of the sheet conveyance path, and the gate unit has a pair of left and right side symmetrical striking faces disposed about the center of the sheet conveyance path. According to yet another aspect of the present invention, a thickness of the sheet is less than about 55 gsm. According to yet another aspect of the present invention, an exemplary image reading device includes the above-described sheet conveying device. According to another aspect of the present invention, an exemplary image forming apparatus includes the above-described sheet conveying device.
Numerous additional modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be executed otherwise than as specifically described herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-141201 | Jun 2012 | JP | national |
