Method for controlling a sheet feeding device (1) comprising an elevator (2) for a stack of sheets, and an air supply system (3) configured to supply and direct one of more air streams towards an upper region (4) of the sheet feeding device for floating a plurality of upper sheets of the stack of sheets, wherein the elevator comprises a vertically movable support (5) for supporting the stack of sheets from below, wherein the sheet feeding device comprises an optical sensor (6) positioned adjacent the floated sheets pot for measuring light reflected from the floated sheets at a plurality of different heights, wherein the method comprises the steps of: continuously deriving from the optical sensor a density reading (DR) indicating the density of sheets floated, continuously deriving an average density (AD) based on a plurality of density readings, continuously deriving an upper density limit (UDL) based on the average density multiplied by a predetermined upper density limit factor (UDLF), continuously deriving a lower density limit (LDL) based on the average density multiplied by a predetermined lower density limit factor (LDLF), adjusting a first operating parameter (OP) of the sheet feeding device should the density reading exceed the upper density limit, wherein the adjustment of the first operating parameter is such as to decrease the density of floated sheets, and adjusting the first operating parameter of the sheet feeding device should the density reading subceed the lower density limit, wherein the adjustment of the first operating parameter is such as to increase the density of floated sheets. Also, a sheet feeding device connected to a controller configured to operate according to this method.

A sensor unit includes an edge detection sensor and an illumination device. The edge detection sensor is disposed in a conveying path of a recording medium and detects a recording medium edge position in a width direction perpendicular to a conveying direction. The illumination device is disposed to face the edge detection sensor in the conveying path and emits light toward the edge detection sensor. The illumination device includes a light source and a diffuser. The light source emits light. The diffuser diffuses the light from the light source and suppresses luminance unevenness.

Example media size sensor assemblies and media handling device including the example media size sensor assemblies are disclosed. In an example, the media size sensor assembly includes a sensor to be mounted within the media handling device, the sensor to detect reflected light. In addition, the media size sensor assembly includes a plurality of reflective surfaces to be coupled to a width adjustment wall of a storage tray of the media handling device, such that movement of the width adjustment wall is to align a selected one of the plurality of reflective surfaces with the sensor. The reflective surfaces of the plurality of reflective surfaces are to reflect different amounts of light.

A document transport device includes a placement portion, a slide member, a movable piece, and a detector. A document is to be placed on the placement portion. The slide member includes a document guide that contacts one lateral side of the document which is placed on the placement portion. The movable piece is provided to the slide member, and includes a shading pattern composed of plural patches that have plural densities corresponding to plural document sizes and having plural adjacent patch density differences that are different from each other. The detector detects a density of the shading pattern, and outputs an output signal for document size recognition.

A measuring device, includes a physical property value detector and a push contact member that pushes to bring a sheet material in contact with the physical property value detector; and further includes a first processor that stops conveyance of the sheet material, pushes to bring the sheet material in contact with the physical property value detector, and detects a physical property value of the sheet material; a second processor that, after having detected the physical property value, cancels the pushing by the push contact member, separates the sheet material from the physical property value detector, and starts conveyance of the sheet material; and a physical property value specifier that specifies the physical property value on a basis of physical property values of a plurality of positions within a surface of the sheet material detected by executing the first processing and the second processing repeatedly.

A sheet stacker includes a housing, a fence, a first distance measurement sensor, and a second distance measurement sensor. The fence is movable in a fence moving direction on the housing and is configured to regulate a position of an end of a sheet. The first distance measurement sensor is configured to measure a distance between the fence and a first portion of the housing, the first portion being on one side of the housing with respect to the fence in the fence moving direction. The second distance measurement sensor is configured to measure a distance between the fence and a second portion of the housing, the second portion being on another side of the housing with respect to the fence in the fence moving direction.

A printing apparatus uses a time of flight sensor to determine distance between the sensor and a surface facing the sensor, and uses a reflectivity value to determine presence of print media in a media bin.

In a medium conveying device, a projector projects light, a projection light amount of the light changes, at every fixed time, to a first projection light amount and a second projection light amount less than the first projection light amount, a receiver receives the light projected from the projector, a processor determines, at fixed sampling timings, whether a reception light amount of the receiver is at a first reception light level or a second reception light level smaller than the first reception light level, determines, when the reception light amount alternately changes to the first reception light level and the second reception light level, that a medium is not present on a conveying path, and determines, when the reception light amount is fixed to either the first reception light level or the second reception light level, that the medium is present on the conveying path.

There is provided a medium transporting device including: a medium placement section on which a medium is placed, a feeding roller feeding a medium from the medium placement section, a motion detection sensor detects a motion of a medium, and a controller that stops feeding of a medium based on a detection value received from the motion detection sensor, in which the motion detection sensor is a two-dimensional sensor including a light emitting section and a light receiving section and detecting a motion of a medium, the medium placement section is provided with a placement detector that acquires information relating to a presence/absence of a medium on the medium placement section, and the controller sets a state of the light emitting section to a non-light emitting state when detection information of the placement detector indicates that a medium is absent on the medium placement section.

A printing apparatus can prevent a print medium from buckling during discharging. In a case in which the print conveyance speed determined by the print mode is higher than or equal to a specified speed, the print medium after printing is conveyed to a discharging tray at the print conveyance speed, and in a case in which the print conveyance speed determined by the print mode is lower than the specified speed, the print medium after printing is conveyed to the discharging tray at the specified speed increased from the print conveyance speed.