Sheet Processing Apparatus And Sheet Processing Method

Abstract

A sheet processing apparatus includes a sheet-table unit, a sheet-separating unit, a discharge unit, a sheet processing unit placed between the sheet-separating unit and the discharge unit, and a speed sensor arranged at the upstream end of the sheet-separating unit, and close to a convey path. The sheets are separated and conveyed downstream by the sheet-separating unit one by one. The speed sensor is capable of detecting the movement start time of each sheet on the convey path and the leaving time of each sheet therefrom, and sending corresponding signals to a system controller. The system controller delays predetermined times according to the received signals to control the sheet processing unit to start and stop processing the sheet which is passing through the sheet processing unit at an even speed.

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 discharge unit located at a downstream end of the sheet-separating unit along the convey direction of the sheets, for discharging the sheets;   a sheet processing unit placed between the sheet-separating unit and the discharge unit, and close to a convey path of the sheets, for processing the sheets;   a speed sensor arranged at an upstream end of the sheet-separating unit, and close to the convey path;   wherein the sheets are separated and conveyed downstream one by one, the speed sensor is capable of detecting the start time of the movement of each sheet on the convey path and the leaving time of each sheet therefrom, and sending corresponding signals to a system controller, the system controller delays predetermined times according to the received signals to control the sheet processing unit to start and stop processing the sheet which is passing through the sheet processing unit at an even speed.   
     
     
         2 . The sheet processing apparatus as set forth in  claim 1 , wherein the speed sensor comprises an illumination for illuminating the closest sheet, a lens for collecting the light reflected from the sheet, an image sensor for recording images on the sheet, and a micro processing unit for processing the images from the image sensor to determine the moving direction and velocity of the sheet, and sending corresponding signals to a signal processing device. 
     
     
         3 . The sheet processing apparatus as set forth in  claim 2 , wherein the signal processing device is capable of comparing the received values of velocity to the predetermined values set therein to judge weather the sheet is moving sufficiently, without the seldom move resulted from an unexpected shake or other factors. 
     
     
         4 . The sheet processing apparatus as set forth in  claim 1 , wherein the speed sensor comprises a roller located beneath the convey path and rotated by the conveying sheet, a time disc rotated with the roller, a photo interrupter sensor and a signal processing device. 
     
     
         5 . The sheet processing apparatus as set forth in  claim 4 , wherein the photo interrupter sensor has an LED mounted at one side of the time disc, and a receiver disposed at the other side of the time disc, the time disc is made from lightproof material and fixed at an end of the roller, a plurality of openings is ring-likely formed on the time disc and arranged at equal intervals, one of which is arranged in alignment with the LED and the receiver for allowing light emitted from LED to pass therethrough for generating two alternate signals by the receiver to transmit to the signal processing device. 
     
     
         6 . The sheet processing apparatus as set forth in  claim 1 , wherein the sheet-table unit has a stacking plate, and at least one pick spring, the stacking plate is disposed obliquely for holding the sheets, the at least one pick spring is arranged to press the sheets for guiding the sheets to reach the sheet-separating unit smoothly. 
     
     
         7 . The sheet processing apparatus as set forth in  claim 6 , further comprising a pick roller mounted in the stacking plate and feeding the sheets towards the sheet-separating unit. 
     
     
         8 . The sheet processing apparatus as set forth in  claim 1 , wherein the sheet-separating unit has a separating roller and a retard roller, with a nip area formed therebetween, a friction coefficient between the separating roller and the sheet is larger than that between the retard roller and the sheet, for feeding the sheet downstream, the friction coefficient between the retard roller and the sheet is larger than that between the two adjacent sheets, for stopping other sheets from moving with the picked sheet. 
     
     
         9 . A sheet processing method, comprising the steps of:
 separating and transporting a plurality of sheets placed on a sheet-table unit one by one along a convey path at an even speed;   detecting the start time of the movement of each sheet on the convey path and sending a corresponding signal to a system controller by a speed sensor;   calculating the time of the sheet arriving at the sheet processing unit on the basis of the received signal, and then controlling the sheet processing unit to start processing the sheet at the time by the system controller;   receiving a signal sent by the speed sensor when the sheet departs from the speed sensor, and calculating the time of the sheet leaving from the sheet processing unit on the basis of the received signal, and controlling the sheet processing unit to stop processing by the system controller; and   discharging the processed sheet by a discharging unit commanded by the system controller.   
     
     
         10 . The sheet processing method as set forth in  claim 9 , wherein the sheets are separated and transported downstream by a sheet-separating unit, the sheet-separating unit has a separating roller and a retard roller, the separating roller is rotated at an outer peripheral linear speed V 1 , a front end of the sheet is against the separating roller and apart from a processing line of the sheet processing unit at a distance L, the system controller sends a control signal to the sheet processing unit for starting processing when the front end of the sheet reaches the processing line of sheet processing unit after a substantially time course L/V 1 . 
     
     
         11 . The sheet processing method as set forth in  claim 10 , wherein another sheet adjacent to the sheet is in static when a rear end of the sheet is apart from the speed sensor, the speed sensor is capable of sensing the state variation of the two adjacent sheets and sending the corresponding control signal to the system controller. 
     
     
         12 . The sheet processing method as set forth in  claim 11 , wherein a length between the rear end of the sheet and the processing line of the sheet processing unit is designated as Q, when the rear end of the sheet is apart from the speed sensor, the system controller receives the control signal resulted from the rear end of the sheet apart from the speed sensor, and sends a control signal to the sheet processing unit for stopping processing after a substantially time course Q/V 1 . 
     
     
         13 . The sheet processing method as set forth in  claim 10 , wherein the discharge unit has a discharge roller rotated at the linear speed V 1  and a discharge pulley, a length from the processing line of the sheet processing unit to a nip area center between the discharge roller and the discharge pulley is defined as a length P, a last sheet, with a rear end thereof located at the processing line of the sheet processing unit, is substantially released from the discharge unit after a time course P/V 1 .