A sensor apparatus includes a photosensitive sensor, a cover, and a moving mechanism. The photosensitive sensor includes a first lens and a second lens which focus on a photosensitive element. The cover includes a first slit arranged on an optical axis of the first lens and a second slit arranged on an optical axis of the second lens. The moving mechanism is configured to move the photosensitive sensor and the cover relative to each other so that the second slit is arranged on the optical axis of the first lens.

An image forming apparatus operable to accept a login of a user by an input of medium information stored in a storage medium or an input via a user interface is provided. The apparatus comprises a storage to store account information that includes user identification information of a registered user and can further include the medium information associated with the user; a reader to read the medium information from the storage medium; a user interface to display a screen and accept an input; and a controller configured to accept a login by a user, wherein the controller, in a case where, at the time of a login of a user via the user interface, the medium information associated with a corresponding user is not registered, registers, in association with the corresponding user, the medium information inputted by the reader.

A processor identifies a specific part composed of a plurality of significant pixels in a mixed-color test image. Furthermore, the processor identifies a color vector. The color vector represents a vector in a color space from one of a color of the specific part in the mixed-color test image and a color of a reference area including a periphery of the specific part to the other. Furthermore, the processor determines which of a plurality of image creating portions of an image forming device corresponding to a plurality of developing colors, is a cause of an image defect, based on the color vector identified from the mixed-color test image.

An image processing apparatus includes an anomaly detecting unit configured to detect anomalies included in a target image; and an anomaly exclusion processing unit configured to exclude a specific anomaly among the detected anomalies. Further, the anomaly exclusion processing unit excludes one of an anomaly and another anomaly among the detected anomalies, if (a) a detection area of the anomaly, a detection area of the other anomaly, and an overlapping area of the detection areas of the anomaly and the other anomaly satisfy a predetermined condition and (b) a type of the anomaly and a type of the other anomaly are different from each other.

The image processing apparatus includes: an abnormality detection unit configured to detect one or more abnormalities included in a target image and an abnormality exclusion processing unit configured to exclude a specific abnormality from the detected one or more abnormalities. In a case in which a detection area of a certain abnormality among the detected one or more abnormalities and a detection area of another abnormality overlap with each other and a type of the certain abnormality and a type of the another abnormality are different from each other, when brightness information of one of the certain abnormality and the another abnormality satisfies a specific condition, the abnormality exclusion processing unit excludes the one of the certain abnormality and the another abnormality from the detected one or more abnormalities.

An image reading apparatus includes a control unit configured to detect occurrence or non-occurrence of multi-sheet feed of a medium based on a reception level signal output by a reception unit in accordance with the received ultrasonic wave. The control unit, after a tip of the medium reaches the positions of the reception unit in a transport path, when the reception level signal is below a predetermined threshold, causes the driving voltage to rise, when an amount of change in the reception level signal in accordance with the rise in the driving voltage is smaller than a reference amount of change, determines that multi-sheet feed is ongoing, and when the amount of change in the reception level signal in accordance with the rise in the driving voltage is greater than the reference amount of change, determines that multi-sheet feed is not ongoing.

A sheet separation device separates a non-bonding portion of a two-ply sheet in which two sheets are overlapped and bonded together at a bonding portion of the two-ply sheet. The sheet separation device includes a separator, an abnormality detection device, and circuitry. The separator is configured to move to be inserted into a gap formed between the two sheets of the two-ply sheet. The abnormality detection device is configured to detect an abnormal state in which the gap larger than a predetermined size is not formed between the two sheets before the separator is inserted into the gap. The circuitry is configured to control movement of the separator based on a result detected by the abnormality detection device.

In a reading device, a controller performs: detecting occurrence of a double-feed; executing a double-feed process; detecting a state of double-fed sheets; executing a first process when a command is inputted; and executing a second process when the command is not inputted. The double feed process includes: halting conveyance of an original document; and making notification of the occurrence of the double-feed. The first process performs, in accordance with the command, one of: resuming the conveyance of the original document; and quitting the conveyance of the original document. The second process performs, in accordance with a determination result, one of: resuming the conveyance of the original document; and continuing the halting and the making. The resuming is performed when the determination result indicates that the conveyance of the original document is possible. The continuing is performed when the determination result indicates that the conveyance of the original document is impossible.

Provided is an inter-shaft distance measuring device for measuring a distance between two shafts or an amount of a change in the distance that includes: measuring elements that are respectively in contact with peripheral surfaces of the two shafts at a time of measurement and that are used as measurement references; a moving mechanism that includes an elastic member and that holds the measuring elements to move the measuring elements relatively and adds a force in opposite directions separating the measuring elements by an elastic force of the elastic member; and a measurer that measures the change in the distance between the measuring elements. In a state at the time of the measurement, the measuring elements between the two shafts add a pressing force by the moving mechanism respectively to the two shafts in directions widening the distance, and the state at the time of the measurement is maintainable.

An image scanner includes a conveyance path and a conveyor that conveys a medium through the conveyance path. The medium bears a detection mark that is spaced from a leading edge of the medium in a medium conveyance direction. A background member is disposed opposite the conveyance path. A luminance sensor is disposed opposite the background member via the conveyance path. The luminance sensor detects a luminance value of each of the background member and the medium. A controller controls the luminance sensor to detect the luminance value at a plurality of times while the conveyor conveys the medium so as to obtain a plurality of detected luminance values. The controller determines a ground color luminance value of a ground color area on the medium based on a determination range including a first peak luminance value among the plurality of detected luminance values.