Buffer device with a reserve buffer to accommodate a printing substrate web supplied with varying speed in an electrographic print device

Abstract

In an electrographic printing device, a printed printing substrate web is supplied to post-processing machines with irregular speed. In order to achieve that the post-processing machines receive the printing substrate web with a continuous speed, a reserve buffer is introduced in which based on sensor control, a loop of the printing substrate web is formed such that, in each operating mode of the printing device, the loop fluctuates around a desired position, with the result that sufficient printing substrate web is always contained in the reserve buffer.

1 . A buffer device with a reserve buffer for accommodation of a printing substrate web supplied with varying speed in an electrographic print device, comprising: 
 at least one operating device arranged in the reserve buffer, an operating force of the operating device acting on the printing substrate web in order to form a loop of the printing substrate web;    sensors scanning the loop arranged in the reserve buffer that emit sensor signals indicating a length of the loop; and    a discharge device controlled by the sensor signals which conveys the printing substrate web with continuous speed from the reserve buffer.    
   
   
       2 . A buffer device according to  claim 1  in which the operating device comprises at least one movable dancing roller.  
   
   
       3 . A buffer device according to  claim 2  in which two of said dancing rollers are provided that are rigidly coupled with one another via a connection web.  
   
   
       4 . A buffer device according to  claim 1  in which three sensors are arranged in a loop direction in the reserve buffer such that 
 the first sensor displays whether the reserve buffer is empty;    the second sensor indicates whether the loop of the printing substrate is in a desired position; and    the third sensor indicates whether the reserve buffer is full.    
   
   
       5 . A buffer device according to  claim 1  in which the sensors comprise light barriers.  
   
   
       6 . A buffer device according to  claim 4  in which a buffer controller, is provided to which the sensor signals are supplied and which controls the discharge device such that the loop fluctuates around the desired position.  
   
   
       7 . A buffer device according to  claim 6  in which the buffer controller controls the discharge device such that it 
 operates with a higher continuous speed when the third sensor indicates with a third sensor signal that the reserve buffer is full, and maintains this continuous speed until the second sensor indicates that the loop is in the desired position;    operates with a lower continuous speed when the first sensor indicates with a first sensor signal that the reserve buffer is empty, and maintains this continuous speed until the second sensor indicates that the loop has reached the desired position; and    operates with an average continuous speed, dependent on an operating mode of the printing device, when the second sensor indicates that the loop is in the desired position.    
   
   
       8 . A buffer device according to  claim 7  in which the buffer controller controls the discharge device such that 
 it operates with an average starting speed, dependent on the operating mode, upon the loop reaching the desired position;    given an under-run of the desired position by the loop in a direction towards the third sensor, the speed is increased until the loop crosses the desired position in a direction towards the first sensor, and then the speed is lowered again; and    a speed at which a duration in which the loop is located over the desired position coincides with a duration in which the loop is located below the desired position is maintained as an average operating speed.    
   
   
       9 . A buffer device according to  claim 8  in which the buffer controller controls the discharge device such that, after a start of the printing device, the discharge device operates after a delay with a speed that corresponds to the average starting speed.  
   
   
       10 . An electrographic printing device, comprising: 
 a printing device supplying a printed substrate supplied with varying speed from the printing device;    a buffer device following the printing device; and    said buffer device comprising at least one operating device, an operating force of the operating device acting on the printing substrate web in order to form a loop of the printing substrate web, sensors scanning the loop arranged in the buffer that emits sensor signals indicating a length of the loop, and a discharge device controlled by the sensor signals which conveys the printing substrate web with continuous speed from the buffer device.    
   
   
       11 . An electrographic printing device according to  claim 10  in which the buffer device is arranged within the printing device.  
   
   
       12 . A method for controlling a discharge device in a reserve buffer for a printing substrate web in an electrographic printing device, comprising the steps of: 
 scanning a loop of the printing substrate web formed by an operating device in the reserve buffer with regard to its position by sensors that emit sensor signals indicating a position of the loop; and    dependent on the sensor signals, with a buffer controller regulating the discharge device such that the loop of the printing substrate web, independent of a speed of supply of the printing substrate web into the reserve buffer in an adjusted state, always fluctuates around a desired position scanned by a sensor.    
   
   
       13 . A method according to  claim 12  in which the buffer controller regulates the discharge device dependent on the sensor signals emitted by first, second, and third sensors arranged in a loop direction in the reserve buffer such that the discharge device 
 operates with higher speed when the third sensor indicates with a respective sensor signal that the reserve buffer is full, and maintains this speed until the second sensor indicates with a respective sensor signal that the loop has achieved the desired position;    operates with lower speed when the first sensor indicates with a respective sensor signal that the reserve buffer is empty, and maintains this speed until the second sensor indicates with its sensor signal that the loop has reached the desired position; and    operates with average speed, dependent on an operating mode of the printing device, when the second sensor indicates that the loop is in the desired position.    
   
   
       14 . A method according to  claim 13  in which the buffer controller regulates the discharge device such that 
 it operates with average initial speed, dependent on the operating mode, upon the loop reaching the desired position;    given an under-run of the desired position by the loop in a direction towards the third sensor, the discharge device increases the speed until the loop crosses the desired position in a direction towards the first sensor, and then the speed is lowered again; and    the discharge device maintains as an average operating speed a speed at which a duration in which the loop is located over the desired position coincides with a duration in which the loop is located below the desired position.    
   
   
       15 . A method according to  claim 14  in which the buffer controller regulates the discharge device such that, after a start of the printing device, the discharge device operates after a delay with a speed that corresponds to the average starting speed.  
   
   
       16 . A method according to  claim 12  wherein a buffer device is provided with said reserve buffer.  
   
   
       17 . A buffer device for accommodation of a printing substrate web supplied with varying speed in an electrographic print device, comprising: 
 at least one operating device, an operating force of the operating device acting on the printing substrate web in order to form a loop of the printing substrate web;    at least one sensor scanning the loop arranged in the reserve buffer that emits sensor signal indicating a position of the loop; and    a discharge device controlled by the sensor signal which conveys the printing substrate web with adjustable continuous speeds from the buffer.    
   
   
       18 . A method for controlling a printing substrate web output from a printing system of an electrographic printing device, comprising the steps of: 
 forming a loop of the printing substrate web with an operating device in contact with the loop and determining a position by at least one sensor that emits a sensor signal indicating a position of the loop; and    dependent on the sensor signal, regulating a discharge device to convey the printing substrate web with adjustable continuous speeds from the buffer.