A sheet conveyance apparatus includes a conveyance unit configured to convey a sheet, a guide member disposed to define a conveyance path, a light-emitting element, a light-receiving element configured to output a detection signal that changes in accordance with an amount of received light, a first light-passing portion disposed to define an optical path from the light-emitting element to the conveyance path, and a second light-passing portion disposed to define an optical path from the conveyance path to the light-receiving element. The light-receiving element is configured such that the detection signal changes in accordance with whether or not a sheet is present in the conveyance path. Reflectance of each of the first light-passing portion and the second light-passing portion to the light emitted from the light-emitting element is higher than reflectance of the guide member to the light emitted from the light-emitting element.

An image forming apparatus includes a print engine to form an image on recording medium, a sensor including first and second electrodes disposed to oppose each other based on a recording medium transport path, along which the recording medium is transported, and to detect a capacitance between the first and second electrodes, and a processor to determine a state of the recording medium fed along the recording medium transport path by using the capacitance detected by the sensor and to control the print engine based on the state of the recording medium.

A post-processing device includes an intermediate tray on which a medium transported in a transport direction is placed, a discharge port through which the medium post-processed on the intermediate tray is discharged, a discharge tray which is disposed in a gravity direction with respect to the discharge port and on which the medium discharged from the discharge port is placed, and an elevating mechanism which elevates the discharge tray, in which the elevating mechanism can move the discharge tray to a first normal position and a first standby position positioned in a direction opposite to the gravity direction with respect to the first normal position, and moves the discharge tray to the first normal position or the first standby position according to an amount of ink before the medium comes in contact with the discharge tray or the medium previously placed on the discharge tray.

A post-processing device includes an intermediate tray on which a medium transported in a transport direction is placed, a discharge port through which the medium post-processed on the intermediate tray is discharged, a discharge tray which is disposed in a gravity direction with respect to the discharge port and on which the medium discharged from the discharge port is placed, and an elevating mechanism which elevates the discharge tray, in which the elevating mechanism can move the discharge tray to a first normal position and a first standby position positioned in a direction opposite to the gravity direction with respect to the first normal position, and moves the discharge tray to the first normal position or the first standby position according to an amount of ink before the medium comes in contact with the discharge tray or the medium previously placed on the discharge tray.

The aligning device receives a sheet conveyed in a sheet conveyance direction in a stackable manner and aligns a position of the sheet in the sheet conveyance direction. The moving mechanism moves the sheet aligned by the aligning device in the sheet conveyance direction together with the aligning device. The controller selectively executes a first mode in which first post-processing is performed on the sheet and then second post-processing is performed on the sheet and a second mode in which the second post-processing is performed on the sheet without performing the first post-processing on the sheet. The controller, in response to a selection of the first mode or the second mode, causes the moving mechanism to adjust a position of the aligning device in the sheet conveyance direction before the aligning device receives the sheet as a target of the first post-processing or the second post-processing, respectively.

The aligning device receives a sheet conveyed in a sheet conveyance direction in a stackable manner and aligns a position of the sheet in the sheet conveyance direction. The moving mechanism moves the sheet aligned by the aligning device in the sheet conveyance direction together with the aligning device. The controller selectively executes a first mode in which first post-processing is performed on the sheet and then second post-processing is performed on the sheet and a second mode in which the second post-processing is performed on the sheet without performing the first post-processing on the sheet. The controller, in response to a selection of the first mode or the second mode, causes the moving mechanism to adjust a position of the aligning device in the sheet conveyance direction before the aligning device receives the sheet as a target of the first post-processing or the second post-processing, respectively.

A post-processing device, includes a tray that accepts a carried sheet and places thereon; a post-processing unit that performs a post-processing to the sheet placed on the tray; and a controller that controls an operation of the post-processing unit. The controller that: obtains both of: a first sheet type specified by a user; and a second sheet type detected by a media detector that is installed on a sheet carrying path; and controls the operation of the post-processing unit based on the second sheet type when the first sheet type and the second sheet type are different.

Paper physical property detecting device includes a first detector that measures a sheet of paper (hereinafter, merely referred to as a paper) made to stop temporarily on a conveyance path and acquires a first value corresponding to a first physical property, a second detector that measures a paper while conveying the paper on the conveyance path and acquires a second value corresponding to a second physical property with regard to a physical property different from the first physical property; and a corrector that corrects the first value on a basis of the second value and creates post correction data.

A liquid discharge apparatus is provided that includes a transport unit configured to transport a medium, a discharge unit configured to discharge a liquid onto the medium, a housing including therein the discharge unit, a humidifying unit configured to humidify an interior of the housing, and a humidity detection unit configured to detect a humidity. When the humidity detection unit detected a humidity less than a lower limit value (one example of a first predetermined value) (positive determination in step S12), the interior of the housing is humidified by the humidifying unit during transport by the transport unit or during discharge by the discharge unit (step S16).

A liquid discharge apparatus is provided that includes a transport unit configured to transport a medium, a discharge unit configured to discharge a liquid onto the medium, a housing including therein the discharge unit, a humidifying unit configured to humidify an interior of the housing, and a humidity detection unit configured to detect a humidity. When the humidity detection unit detected a humidity less than a lower limit value (one example of a first predetermined value) (positive determination in step S12), the interior of the housing is humidified by the humidifying unit during transport by the transport unit or during discharge by the discharge unit (step S16).