Document transport device, document transport method, and document transport control system

Abstract

A theoretical threshold corresponding to a transport path is set, and a control unit acquires a calculation value calculated based on a detection result of double feeding detection unit and a transport length of a document, determines occurrence of double feeding when the calculation value is greater than the theoretical threshold (step S120), and determines non-occurrence of double feeding when the calculation value is smaller than the theoretical threshold. In addition, if a non-detection period for double feeding occurs (step S110), the control unit sets a cumulative value in step S115. As a result, detection of double feeding is ended in a short period while a document is being transported, and in a case that double feeding is no longer detected, determination of double feeding will not be made.

What is claimed is: 
     
         1 . A document transport device comprising:
 a placement unit on which a document is placed;   a transport unit configured to transport the document placed on the placement unit along a predetermined transport path;   a processing unit configured to perform processing on the transported document;   a double feeding detection unit configured to detect double feeding of the document along the transport path; and   a control unit configured to determine occurrence of double feeding, wherein   the control unit acquires a calculation value that is a detection result of the double feed detection unit from when a double feed is detected until the next time when the double feed is no longer detected and a theoretical threshold to be compared with the calculation value when determining occurrence of double feeding, executes a first mode in which the calculation value is used to determine occurrence of double feeding, and a second mode in which the total value of the calculation values is used to determine occurrence of double feeding, in the first mode, determines the occurrence of double feeding when the calculation value is greater than the theoretical threshold, and determines non-occurrence of double feeding when the calculation value is smaller than the theoretical threshold.   
     
     
         2 . The document transport device according to  claim 1 , wherein
 the double feeding detection unit detects double feeding of the document at a fixed interval,   the calculation value is a cumulative value obtained by counting the number of times double feeding is detected at a fixed interval in a period in which double feeding is detected, and   the control unit resets the cumulative value when double feeding is no longer detected and the cumulative value does not meet the theoretical threshold.   
     
     
         3 . The document transport device according to  claim 1 , wherein the theoretical threshold is a value obtained by subtracting a variation in an end portion of a specific document in a transport direction from a length of the specific document in the transport direction. 
     
     
         4 . The document transport device according to  claim 1 , wherein
 the transport unit includes a first pair of transport rollers that transport the document to the processing unit and a second pair of transport rollers that transport the document processed by the processing unit, and   a length of a specific document in a direction in which the document is transported is longer than a length from a nip position of the first pair of transport rollers to a nip position of the second pair of transport rollers.   
     
     
         5 . The document transport device according to  claim 4 , wherein the specific document is a business card. 
     
     
         6 . The document transport device according to  claim 1 , wherein the specific document is an instant photographic sheet. 
     
     
         7 . The document transport device according to  claim 1 , comprising:
 an operation unit configured to receive an operation of a user, wherein   the control unit is configured to change the theoretical threshold based on information input from the operation unit.   
     
     
         8 . The document transport device according to  claim 1 , wherein the control unit selects the first mode or the second mode based on a result of determining whether a thin document is transported. 
     
     
         9 . The document transport device according to  claim 1 , wherein the processing unit is a reading unit configured to read the transported document. 
     
     
         10 . A document transport method of a document transport device including a placement unit on which a document is placed, a transport unit configured to transport the document placed on the placement unit along a predetermined transport path, a processing unit configured to perform processing on the transported document, and a double feeding detection unit configured to detect double feeding of the document along the transport path, the document transport method comprising:
 acquiring a calculation value that is a detection result of the double feed detection unit from when a double feed is detected until the next time when the double feed is no longer detected and a theoretical threshold to be compared with the calculation value when determining occurrence of double feeding; and   selecting a first mode in which the calculation value is used to determine occurrence of double feeding, and a second mode in which the total value of the calculation values is used to determine occurrence of double feeding,   in the first mode, determining occurrence of double feeding when the calculation value is greater than the theoretical threshold, and determining non-occurrence of double feeding when the calculation value is smaller than the theoretical threshold.   
     
     
         11 . A document transport control system comprising:
 a document transport device including a placement unit on which a document is placed, a transport unit configured to transport the document placed on the placement unit along a predetermined transport path, a processing unit configured to perform processing on the transported document, and a double feeding detection unit configured to detect double feeding of the document along the transport path; and   a control device configured to control the document transport device, wherein   the control device acquires a calculation value that is a detection result of the double feed detection unit from when a double feed is detected until the next time when the double feed is no longer detected and a theoretical threshold to be compared with the calculation value when determining occurrence of double feeding, is capable of executing a first mode in which the calculation value is used to determine occurrence of double feeding, and a second mode in which the total value of the calculation values is used to determine occurrence of double feeding, in the first mode, determines the occurrence of double feeding when the calculation value is greater than the theoretical threshold, and determines non-occurrence of double feeding when the calculation value is smaller than the theoretical threshold.