Paper feeder and image forming apparatus

Abstract

A paper feeder includes a tray; a delivery roller; a paper feed roller; a guide member that guides the delivered sheet from the tray toward the paper feed roller; a lifting/lowering mechanism capable of changing a height of the tray; and a controller that executes paper feed processing, wherein the controller has: a setting device that accepts job settings including settings related to plural types of sheets, the plural types of sheets including a first sheet and a second sheet that is thicker than the first sheet; and a lifting/lowering controller that controls the lifting/lowering mechanism such that, in the case where the second sheet is set, before initiation of the paper feed processing, a height of the tray with respect to the guide member becomes higher by a first predetermined magnitude than that in the case where the first sheet is set.

What is claimed is: 
     
         1 . A paper feeder comprising:
 a tray in which a sheet can be placed;   a delivery roller that delivers the sheet placed in the tray;   a paper feed roller that feeds the delivered sheet to a conveyance path;   a guide member that guides the delivered sheet from the tray toward the paper feed roller and is provided to be inclined upward toward the paper feed roller;   a lifting/lowering mechanism capable of changing a height of the tray; and   a controller that executes paper feed processing to feed the delivered sheet from the tray to the conveyance path by causing the paper feed roller to rotate, wherein   the controller has: a setting device that accepts job settings including settings related to plural types of sheets, the plural types of sheets including a first sheet and a second sheet that is thicker than the first sheet; and a lifting/lowering controller that controls the lifting/lowering mechanism such that, in the case where the second sheet is set, before initiation of the paper feed processing, a height of the tray with respect to the guide member becomes higher by a first predetermined magnitude than that in the case where the first sheet is set.   
     
     
         2 . The paper feeder according to  claim 1  further comprising:
 a first detector that is arranged on a downstream side of the paper feed roller and detects the sheet fed by the paper feed roller, wherein, 
 in the case where the fed sheet is not detected by the first detector in the paper feed processing, the controller can execute retry processing to stop the paper feed processing and thereafter restart the paper feed processing, and the lifting/lowering controller controls the lifting/lowering mechanism such that, in the case where the second sheet is set, and the fed sheet is not detected by the first detector during the paper feed processing, the tray is further lifted by a predetermined magnitude with respect to the guide member in a period after the paper feed processing is stopped and before the paper feed processing is restarted in the retry processing. 
 
     
     
         3 . The paper feeder according to  claim 1  further comprising:
 a first detector that is arranged on a downstream side of the paper feed roller and detects the sheet fed by the paper feed roller, wherein, 
 in the case where the fed sheet is not detected by the first detector in the paper feed processing, the controller can execute retry processing to stop the paper feed processing and thereafter restart the paper feed processing, and, in the case where the first sheet is set, and the fed sheet is not detected by the first detector during the paper feed processing, the lifting/lowering controller executes the retry processing without lifting the tray with respect to the guide member. 
 
     
     
         4 . The paper feeder according to  claim 1 , wherein
 the controller further has a counter for counting the number of the fed sheets that is the number of the sheets fed by the paper feed roller, and the lifting/lowering controller controls the lifting/lowering mechanism such that, in the case where the second sheet is set, and it is determined that the number of the fed sheets is equal to or larger than a predetermined threshold during the paper feed processing, the tray is further lifted with respect to the guide member.   
     
     
         5 . The paper feeder according to  claim 1  further comprising:
 A second detector that detects the sheet placed in the tray, wherein, 
 in the case where the sheet placed in the tray is detected, and an instruction to start the job set for the second sheet is accepted via an operation acceptor, the lifting/lowering controller continuously lifts the tray from an initial position to a height position for a case where the second sheet is set. 
 
     
     
         6 . The paper feeder according to  claim 1  further comprising:
 a second detector that detects the sheet placed in the tray, wherein, 
 in the case where the sheet placed in the tray is detected, and any operation input is accepted via an operation acceptor, the lifting/lowering controller lifts the tray from an initial position to a height position for a case where the first sheet is set, and, in the case where an instruction to start the job set for the second sheet is accepted via the operation acceptor, the lifting/lowering controller lifts the tray from the height position for the case where the first sheet is set to a height position for a case where the second sheet is set. 
 
     
     
         7 . The paper feeder according to  claim 1 , wherein
 the guide member has a guide surface that is inclined upward toward the paper feed roller, and the lifting/lowering controller controls the lifting/lowering mechanism such that, in the case where the second sheet is set, an angle of a placement surface on which the sheet is placed in the tray with respect to the guide surface becomes smaller than that in the case where the first sheet is set.   
     
     
         8 . The paper feeder according to  claim 1 , wherein,
 The setting device can accept, as one of the settings related to the plural types of sheets, a setting related to a third sheet that is thinner than the first sheet, and, the lifting/lowering controller controls the lifting/lowering mechanism such that, in the case where the third sheet is set, before initiation of the paper feed processing, the height of the tray with respect to the guide member becomes higher by a second predetermined magnitude, which is smaller than the first predetermined magnitude, than that in a case where the first sheet is set.   
     
     
         9 . The paper feeder according to  claim 1 , wherein,
 the setting device can accept, as one of the settings related to the plural types of sheets, a setting related to a fourth sheet that is thicker than the first sheet and is smaller in size than the first sheet, and, the lifting/lowering controller controls the lifting/lowering mechanism such that, in the case where the fourth sheet is set, before initiation of the paper feed processing, the height of the tray with respect to the guide member becomes higher by a third predetermined magnitude than that in a case where the first sheet is set.   
     
     
         10 . An image forming apparatus comprising: the paper feeder according to  claim 1 .