Determining device, conveying device, image reading device, and image forming apparatus

Abstract

A determining device includes an acquisition processing portion and a determination processing portion. The acquisition processing portion acquires a signal based on an ultrasonic wave emitted toward an object conveyed in a specific direction. The determination processing portion determines whether or not a first time period is equal to or larger than a predetermined first time threshold, wherein the first time period is a time period during which a level of the signal changes from a predetermined first level threshold to a second level threshold that is smaller than the first level threshold.

1 . A determining device comprising:
 an acquisition processing portion configured to acquire a signal based on an ultrasonic wave emitted toward an object conveyed in a specific direction; and   a determination processing portion configured to determine whether or not a first time period is equal to or larger than a predetermined first time threshold, wherein the first time period is a time period during which a level of the signal changes from a predetermined first level threshold to a second level threshold that is smaller than the first level threshold.   
     
     
         2 . The determining device according to  claim 1 , wherein
 the first time threshold is determined based on: a velocity at which the object is conveyed in the specific direction; and a distance from an end of the object on the first direction side in a reverse direction of the specific direction.   
     
     
         3 . The determining device according to  claim 1 , wherein
 the first level threshold and the second level threshold are determined based on a thickness of the object in an intersecting direction that intersects the specific direction.   
     
     
         4 . The determining device according to  claim 1 , wherein
 upon determining that the first time period is not equal to or larger than the first time threshold, the determination processing portion further determines whether or not a second time period is equal to or larger than a second time threshold, wherein the second time period is a time period in which the level of the signal is equal to or smaller than the first level threshold, and the second time threshold is longer than the first time threshold.   
     
     
         5 . The determining device according to  claim 4 , wherein
 the second time threshold is determined based on: a velocity at which the object is conveyed in the specific direction; and a length of the object in the specific direction.   
     
     
         6 . A conveying device comprising:
 a sensor portion configured to emit an ultrasonic wave toward the object, and output the signal having a level that changes according to an incident wave from the object; and   the determining device according to  claim 1 .   
     
     
         7 . The conveying device according to  claim 6 , further comprising:
 a detection processing portion configured to detect whether or not a double feeding of the object has occurred, based on a determination result of the determining device.   
     
     
         8 . The conveying device according to  claim 7 , wherein
 when the determination processing portion determines that the first time period is equal to or larger than the first time threshold, the detection processing portion detects that a double feeding has not occurred,   the conveying device further comprising:   a conveyance controlling portion configured to, when the detection processing portion detects that a double feeding has not occurred, further convey the object toward a downstream in the specific direction.   
     
     
         9 . The conveying device according to  claim 8 , wherein
 when the determination processing portion determines that the first time period is not equal to or larger than the first time threshold, the detection processing portion detects that a double feeding has occurred, and   when the detection processing portion detects that a double feeding has occurred, the conveyance controlling portion stops conveying the object in the specific direction.   
     
     
         10 . An image reading device comprising:
 the determining device according to  claim 1 .   
     
     
         11 . An image reading device comprising:
 the conveying device according to  claim 6 .   
     
     
         12 . An image forming apparatus comprising:
 the determining device according to  claim 1 .   
     
     
         13 . An image forming apparatus comprising:
 the conveying device according to  claim 6 .