A measurement apparatus includes a first conveyance path, a second conveyance path, a measuring portion, a third conveyance path and a sheet stacking portion. A sheet discharged out of an image forming apparatus is conveyed toward a downstream apparatus through the first conveyance path. The second conveyance path is branched from the first conveyance path, extended below the first conveyance path, and merged with the first conveyance path. The measuring portion is disposed on the second conveyance path. The third conveyance path is provided above the first conveyance path and is configured to convey the sheet from which a test image has been measured by the measuring portion in the second conveyance path. The sheet stacking portion is provided above the first conveyance path, and the sheet discharged out of the third conveyance path is stacked on the sheet stacking portion.

An image reading apparatus includes a reading unit, a transport unit that transport a document, a feeding unit that transports the document to the transport unit, a controller that stops the feeding operation of the feeding unit after the leading end of the preceding document transported from the feeding unit reaches the transport unit and restarts the feeding operation after the rear end of the preceding document passes a predetermined position. The controller, restarts the feeding operation a first time after the rear end of the succeeding document following the preceding document passes the predetermined position when a size of the preceding document indicates a first size, and restarts the feeding operation a second time after the rear end of the succeeding document passes the predetermined position where the second time is longer than the first time when the size indicates a second size larger than the first size.

An image reading apparatus includes a reading unit, a transport unit that transport a document, a feeding unit that transports the document to the transport unit, a controller that stops the feeding operation of the feeding unit after the leading end of the preceding document transported from the feeding unit reaches the transport unit and restarts the feeding operation after the rear end of the preceding document passes a predetermined position. The controller, restarts the feeding operation a first time after the rear end of the succeeding document following the preceding document passes the predetermined position when a size of the preceding document indicates a first size, and restarts the feeding operation a second time after the rear end of the succeeding document passes the predetermined position where the second time is longer than the first time when the size indicates a second size larger than the first size.

In one example of the disclosure, an uncalibrated sensor may be calibrated. Calibrated sensor data is obtained. The data relates to an amount of light transmitted through an ink solution of a first colour as a function of ink concentration. An amount of light transmitted through an ink solution of the first colour is measured, using the uncalibrated sensor, at a plurality of ink concentrations. A calibration factor relating the light transmission of the calibrated sensor for the first colour and the light transmission of the uncalibrated sensor for the first colour is determined, using a processor, based on the obtained data and the measurements.

In one example of the disclosure, an uncalibrated sensor may be calibrated. Calibrated sensor data is obtained. The data relates to an amount of light transmitted through an ink solution of a first colour as a function of ink concentration. An amount of light transmitted through an ink solution of the first colour is measured, using the uncalibrated sensor, at a plurality of ink concentrations. A calibration factor relating the light transmission of the calibrated sensor for the first colour and the light transmission of the uncalibrated sensor for the first colour is determined, using a processor, based on the obtained data and the measurements.

The image forming apparatus includes: a printing section for conveying a sheet of paper; a reversal section for reversing top-and-back orientation of a sheet; and a control section for, based on an output of an image detection sensor resulting when a sheet has passed through a detection position for the first time, detecting whether or not a first surface is a blank surface, and moreover, based on an output of the image detection sensor resulting when the sheet subjected to reversal process has once again passed through the detection position, detecting whether or not a second surface is a blank surface, whereby the control section decides whether a sheet feed cassette is a back-sided sheet-containing cassette or a new sheet-containing cassette.

The image forming apparatus includes: a printing section for conveying a sheet of paper; a reversal section for reversing top-and-back orientation of a sheet; and a control section for, based on an output of an image detection sensor resulting when a sheet has passed through a detection position for the first time, detecting whether or not a first surface is a blank surface, and moreover, based on an output of the image detection sensor resulting when the sheet subjected to reversal process has once again passed through the detection position, detecting whether or not a second surface is a blank surface, whereby the control section decides whether a sheet feed cassette is a back-sided sheet-containing cassette or a new sheet-containing cassette.

A media registration system including an accumulation region and a transport track to receive and transport each media sheet of a series of media sheets forming a media job in a transport direction from an intake end to a registration end proximate to the accumulation region, and to stack the media sheets of the media job in the accumulation region to form a job stack. A translator adjusts a position of the registration end of the transport track in a direction lateral to the transport direction for each sheet to align edges of each sheet of the job stack in the lateral direction. A media sensor indicates a position of each sheet along the media path to facilitate a controller to determine an accumulation status of the job stack.

A controller of a sheet stacking device executes tray elevating processing and sheet stacking processing. The tray elevating processing is processing in which when a sensor detects an uppermost sheet, the controller once lowers a stacking tray, and lifts the stacking tray until the sensor detects the uppermost sheet. The sheet stacking processing is processing in which the controller arranges a guide arm at an advanced position to guide the sheet, arranges the guide arm at a retracted position before a rear end of the sheet passes the sheet discharge portion, and stacks the sheet on the stacking tray after the rear end of the sheet passes the sheet discharge portion. The controller executes the tray elevating processing in a state where the guide arm is disposed at the advanced position during the execution of the sheet stacking processing.

A controller of a sheet stacking device executes tray elevating processing and sheet stacking processing. The tray elevating processing is processing in which when a sensor detects an uppermost sheet, the controller once lowers a stacking tray, and lifts the stacking tray until the sensor detects the uppermost sheet. The sheet stacking processing is processing in which the controller arranges a guide arm at an advanced position to guide the sheet, arranges the guide arm at a retracted position before a rear end of the sheet passes the sheet discharge portion, and stacks the sheet on the stacking tray after the rear end of the sheet passes the sheet discharge portion. The controller executes the tray elevating processing in a state where the guide arm is disposed at the advanced position during the execution of the sheet stacking processing.