US20110187041A1 - Sheet processing apparatus - Google Patents

Abstract

A sheet processing apparatus includes a sheet-table unit, a sheet-separating unit, a convey unit, a discharge unit, a sheet processing unit, and a sensor arranged at an upstream end of the convey unit and spaced from the discharge unit with a predetermined distance. The convey unit has a convey roller, a convey pulley, and an elastic device connected with the convey pulley. The elastic device has a cylinder, a fixing shaft fixed to the cylinder, and a spring having two free ends fixed to the fixing shaft and a portion of the convey pulley opposite to the convey roller. When the signal resulted from a rear end of the sheet apart from the sensor is sent to the system controller, the cylinder is commanded by the system controller to draw back the fixing shaft. The spring is elongated to make the convey pulley away from the convey roller.

Description

BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• This present invention relates to a sheet processing apparatus, and more specifically to a sheet processing apparatus having a feeding structure which improves the stability of sheet feeding.
• 2. The Related Art
• Please refer toFIG. 1, a conventionalsheet processing apparatus100′ comprises a sheet-separating unit1′ which includes aseparating roller11′ and afirst driving device12′, asensor2′, aconvey unit3′, a sheet-processing unit4′, adischarge unit5′, asecond driving device7′ and asystem controller8′. The separatingroller11′ is commanded by thefirst driving device12′ to rotate anticlockwise for separating and feeding a sheet (not shown). Theconvey unit3′ has aconvey roller31′, aconvey pulley32′ disposed against theconvey roller31′, with aconvey path6′ defined therebetween, aswingable arm33′ and adriving device34′. Theswingable arm33′ has one free end pivoted to theconvey pulley32′, and the other free end connected to thedriving device34′, thereby forcing theconvey pulley32′ to move with respect to theconvey roller31′ under the drive of thedriving device34′. Herein, theswingable arm33′ has a middle portion pivoted to a housing (not shown). The sheet-processing unit4′ is capable of scanning, printing and copying a plurality of sheets.
• Take scanning the sheet for example, when thesheet processing apparatus100′ is in work, the plural sheets are disposed at an original end of the separatingroller11′. The separatingroller11′ is urged by thefirst driving device12′ to rotate for feeding one sheet downstream along theconvey path6′. Thesensor2′ detects a front end of the sheet and sends a signal to thesystem controller8′. Thesecond driving device7′ is accordingly commanded by thesystem controller8′ to operate theconvey roller31′ and thedischarge unit5′ to rotate. Consequently, the sheet will be conveyed downstream successively by the rotatedconvey roller31′ to process by the sheet-processing unit4′. When the front end of the sheet reaches thedischarge unit5′, a rear end of the sheet is still restrained between theconvey roller31′ and the conveypulley32′. At this time, thesystem controller8′ controls thedriving device34′ to bright theswingable arm33′ to swing so that theconvey pulley32′ is moved away from theconvey roller31′ with a small distance, releasing the conveying sheet. Thus the sheet will be conveyed only by thedischarge unit5′, avoiding pulling and dragging the sheet.
• However, since thesheet processing apparatus100′ provides with theswingable arm33′, served as a transitional element, for forcing theconvey pulley32′ to butt against and separate the sheets from theconvey roller31′, the assembling inaccuracy and the attrition of theswingable arm33′ is possible and apt to affect the engagement between theconvey roller31′ and theconvey pulley32′, as a result, having bad influence on the conveying stability for sheets.
SUMMARY OF THE INVENTION
• An object of the invention is to provide a sheet processing apparatus having a feeding structure which improves the stability of sheet feeding. The sheet processing apparatus adapted for processing a plurality of sheets includes a sheet-table unit for holding the sheets, a sheet-separating unit disposed at a downstream end of the sheet-table unit along a convey direction of the sheets, for separating the sheets one by one and feeding the sheets downstream, a convey unit arranged at a downstream end of the sheet-separating unit along the convey direction of the sheets, for feeding the sheets downstream, a discharge unit located at a downstream end of the convey unit along the convey direction of the sheets, for discharging the sheets, a sheet processing unit placed between the convey unit and the discharge unit, and close to a convey path of the sheets, for processing the sheets, and a sensor arranged at an upstream end of the convey unit and spaced away from the discharge unit with a predetermined distance, for detecting the sheets and sending signals to a system controller. The convey unit has a convey roller, a convey pulley detachably resting against the convey roller, and an elastic device connected with the convey pulley. The elastic device has a cylinder, a fixing shaft having one end fixed to the cylinder, and a spring having two free ends fixed to the other end of the shaft and a portion of the convey pulley opposite to the convey roller. The convey pulley is forced by the spring to rest against the convey roller resiliently for conveying the sheet. When the signal resulted from a rear end of the sheet apart from the sensor is sent to the system controller, the cylinder is commanded by the system controller to draw back the fixing shaft. The spring is accordingly elongated to make the convey pulley away from the convey roller for releasing the conveying sheet.
• As described above, the sheet processing apparatus is provided with the elastic device which is capable of forcing the convey pulley to rest against the convey roller for conveying the sheets stably, and separate the sheets from the convey roller before the front end of the sheet enters into the discharge unit, thereby releasing the rear end of the sheet for preventing from pulling and dragging the sheets. The elastic device is simple and convenient to manufacture and assemble. Furthermore, the elastic device provides the cylinder to bright the convey pulley to move, which guarantees the constant engagement between the convey roller and the convey pulley in a long time use.
BRIEF DESCRIPTION OF THE DRAWINGS
• The invention, together with its object and the advantages thereof may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which:
• FIG. 1 is a schematic sectional view of a sheet processing apparatus in prior art;
• FIG. 2 is a schematic sectional view of a sheet processing apparatus according to an embodiment of the present invention; and
• FIGS. 3-8 are schematic sectional views illustrating the different states of a sheet in the conveying process of the sheet processing apparatus shown inFIG. 2.
DETAILED DESCRIPTION OF THE EMBODIMENT
• Referring toFIGS. 2-3, asheet processing apparatus100 of the embodiment according to the present invention is shown. Thesheet processing apparatus100 comprises a sheet-table unit1, a sheet-separating unit2, afirst sensor3 connected with asystem controller81, aconvey unit4, asecond sensor5 connected with thesystem controller81, a sheet-processing unit6 connected with thesystem controller81, and adischarging unit7, with a convey path defined and passing therethrough for conveying a plurality ofsheets9.
• Please refer toFIG. 3, the sheet-table unit1 holds thesheets9 and has a feeding device (not shown) for feeding thesheets9 toward the downstream sheet-separatingunit2. The sheet-separatingunit2 has a separatingroller21 and aretard roller22 disposed upon the separatingroller21, with a nip area formed therebetween. Theretard roller22 is controlled by a twisting device (not shown). A friction coefficient between the separatingroller21 and thesheet9 is larger than that between theretard roller22 and thesheet9, for feeding each of theplural sheets9 forwards. The friction coefficient between theretard roller22 and thesheet9 is larger than that between the twoadjacent sheets9, for stopping theplural sheets9 from moving forwards except for the lowermost one. Herein, theretard roller22 can be replaced by a retard pad. When the separatingroller21 is rotated anticlockwise, thelowermost sheet9 is conveyed forward under the action of the friction force, butother sheets9 is stopped by theretard roller22, thereby separating thesheets9 one by one.
• Thefirst sensor3 is disposed at a downstream end of the sheet-separatingunit2, and close to the convey path of thesheets9. Thefirst sensor3 has a sensor arm which is pushed by thesheets9 from a position to another position and automatically returns the original position when thesheets9 are departed therefrom. Thefirst sensor3 sends different signals to thesystem controller81 when the sensor arm is located at different positions (two positions).
• Theconvey unit4 is disposed at a downstream end of thefirst sensor3, and has aconvey roller41, aconvey pulley42 disposed against theconvey roller41, and anelastic device43 connected with theconvey pulley42. Theelastic device43 has acylinder430, afixing shaft431, abarrel432 and aspring433. Thefixing shaft431 has one end fixed to thecylinder430, and the other end connected with one free end of thespring433. Thespring433 is received in thebarrel432 and has the other free end connected with a portion of theconvey pulley42 opposite to a portion of theconvey pulley42 resting against theconvey roller41 for providing the elastic force with theconvey pulley42 to make theconvey pulley42 rest against theconvey roller41 resiliently. Thecylinder430 is connected with thesystem controller81.
• Thesecond sensor5, which has a structure same as that of thefirst sensor3, is disposed at a downstream end of theconvey unit4, and capable of detecting thesheet9 when thesheet9 is arrived thereat and sending a signal to thesystem controller81. The sheet-processing unit6 is disposed at a downstream end of thesecond sensor5 and commanded by thesystem controller81 for processing thesheets9. Thedischarge unit7 is disposed at a downstream end of the sheet-processing unit6 and spaced away from thefirst sensor3 with a predetermined distance. Thedischarge unit7 has adischarge roller71 and adischarge pulley72 disposed against thedischarge roller71 for discharging the processedsheets9. Thesystem controller81 is connected with thefirst sensor3, thecylinder430, thesecond sensor5 and the sheet-processing unit6. Afirst driving device82 is commanded by thesystem controller81 to force the separatingroller21 to rotate anticlockwise, and asecond driving device83 is commanded by thesystem controller81 for driving theconvey roller41 and thedischarge roller71 to rotate anticlockwise.
• Please refer toFIGS. 2-4, when thesheet processing apparatus100 is in work, at least onesheet9 is put on the sheet-table unit1, and conveyed to the nip area of sheet-separatingunit2. Herein, thesheet9 defines afront end91 and arear end92. The sheet-separatingunit2 separates and conveys onesheet9 towards thefirst sensor3. When thefront end91 arrives at thefirst sensor3, thefirst sensor3 detects thefront end91 and sends a signal to thesystem controller81. Accordingly, thesystem controller81 controls thesecond driving device83 to drive the conveyroller41 and thedischarge roller71 to starting turning. Thus the conveyroller41 is able to convey thesheet9 successively. When thefront end91 contacts thesecond sensor5, thesystem controller81 controls the sheet-processing unit6 to start processing thesheet9 at a proper time under the condition of receiving a signal from thesecond sensor5.
• With reference toFIGS. 5-7, when thefront end91 of thesheet9 is going to enter into a nip area of thedischarge unit7, therear end92 departs from thefirst sensor3. Thefirst sensor3 generates and sends a signal to thesystem controller81. Thecylinder430 of theelastic device43, commanded by thesystem controller81, forces the fixingshaft431 to move towards thecylinder430, elongating thespring433. Consequently, the conveypulley42 is urged by thespring433 to move away from the conveyroller41 for reducing the pressing force acted on thesheet9. Thesystem controller81 is capable of calculating the time course of therear end92 conveyed from thefirst sensor3 to thedischarge unit4, in accordance with the signal resulted from therear end92 leaving thefirst sensor3, and setting the time point of thecylinder430 driven by thesecond driving device83 to release thespring433 to return the original position, when the rear end93 is apart from thedischarge unit4.
• Referring toFIG. 8, thesecond sensor5 sends a signal to thesystem controller81 as therear end92 leaves therefrom. Thesystem controller81 is going to control the sheet-processing unit6 to stop scanning thesheet9 after a predetermined time course when therear end92 departs from a scanning center line of the sheet-processing unit6. Thus thesheet9 is processed and discharged by thedischarge unit7. Theother sheets9 are processed in the same manner as mentioned above.
• As described above, thesheet processing apparatus100 is provided with theelastic device43 which is capable of forcing the conveypulley42 to rest against the conveyroller41 for conveying thesheets9 stably, and separate from the conveyroller41 before thefront end91 of thesheet9 enters into thedischarge unit7, thereby releasing therear end92 of thesheet9 for preventing from pulling and dragging thesheets9. Theelastic device43 is simple and convenient to manufacture and assemble. Furthermore, theelastic device43 provides thecylinder430 to bright the conveypulley42 to move, which guarantees the constant engagement between the conveyroller41 and the conveypulley42 in a long time use.

Claims (7)

1. A sheet processing apparatus adapted for processing a plurality of sheets, comprising:

a sheet-table unit for holding the sheets;

a sheet-separating unit disposed at a downstream end of the sheet-table unit along a convey direction of the sheets, for separating the sheets one by one and feeding the sheets downstream;

a convey unit arranged at a downstream end of the sheet-separating unit along the convey direction of the sheets, for feeding the sheets downstream, the convey unit having a convey roller, a convey pulley detachably resting against the convey roller, and an elastic device connected with the convey pulley, the elastic device having a cylinder, a fixing shaft having one end fixed to the cylinder, and a spring having two free ends fixed to the other end of the fixing shaft and a portion of the convey pulley opposite to the convey roller;

a discharge unit located at a downstream end of the convey unit along the convey direction of the sheets, for discharging the sheets;

a sheet processing unit placed between the convey unit and the discharge unit, and close to a convey path of the sheets, for processing the sheets; and

a sensor arranged at an upstream end of the convey unit and spaced away from the discharge unit with a predetermined distance, for detecting the sheets and sending signals to a system controller;

wherein the convey pulley is forced by the spring to rest against the convey roller resiliently for conveying the sheet, when the signal resulted from a rear end of the sheet apart from the sensor is sent to the system controller, the cylinder is commanded by the system controller to draw back the fixing shaft, the spring is accordingly elongated to make the convey pulley away from the convey roller for releasing the conveying sheet.

2. The sheet processing apparatus as set forth inclaim 1, wherein the system controller drives the convey roller to rotate when the system controller receives the signal resulted from the sensor detecting a front end of the sheet.

3. The sheet processing apparatus as set forth inclaim 2, wherein the discharge unit has a discharge roller and a discharge pulley disposed against the discharge roller, the system controller controls the discharge roller to rotate when the system controller receives the signal resulted from the sensor detecting a front end of the sheet.

4. The sheet processing apparatus as set forth inclaim 3, further comprising a driving device which is commanded by the system controller to drive the convey roller and the discharge roller to rotate.

5. The sheet processing apparatus as set forth inclaim 1, wherein the sheet-separating unit has a separating roller and a retard roller disposed against the separating roller.

6. The sheet processing apparatus as set forth inclaim 5, further comprising a first driving device which is commanded by the system controller to drive the separating roller to rotate for feeding the sheets.

7. The sheet processing apparatus as set forth inclaim 1, wherein the elastic device further has a barrel surrounding the spring.

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