Abstract: An image forming device including an optical sensor, an ultrasound sensor, and a conveyance guide. The optical sensor and the ultrasound sensor are disposed alongside a conveyance path of a sheet and are used to determine sheet type. The conveyance guide guides the sheet along the conveyance path. The conveyance guide is structured such that, on the conveyance path between the optical sensor and the ultrasound sensor, the sheet is in contact with the conveyance guide while a portion of the sheet is in a light irradiation range of the optical sensor and a different portion of the sheet is in an ultrasound irradiation range of the ultrasound sensor.

Abstract: An image forming apparatus includes: a first rotor and a second rotor that are each a rotatable member; a first movable member including the first rotor or a transferer that transfers power of the first rotor to another member; a second movable member including the second rotor or a transferer that transfers power of the second rotor to another member; a hardware processor that drives simultaneously the first rotor and the second rotor at mutually different numbers of revolutions or speeds, and performs abnormality diagnosis on the first movable member and the second movable member, based on the sounds of operation acquired by the sound acquirer; and a sound acquirer that acquires sounds of operation of the first movable member and the second movable member with the first rotor and the second rotor being driven by the hardware processor.

Abstract: An image forming apparatus includes: a first rotor and a second rotor that are each a rotatable member; a first movable member including the first rotor or a transferer that transfers power of the first rotor to another member; a second movable member including the second rotor or a transferer that transfers power of the second rotor to another member; a hardware processor that drives simultaneously the first rotor and the second rotor at mutually different numbers of revolutions or speeds, and performs abnormality diagnosis on the first movable member and the second movable member, based on the sounds of operation acquired by the sound acquirer; and a sound acquirer that acquires sounds of operation of the first movable member and the second movable member with the first rotor and the second rotor being driven by the hardware processor.

Abstract: An abnormality determination apparatus includes: an audio data acquisitor that acquires audio data of an apparatus to be judged for determining presence or absence of abnormality; an abnormal sound detector that detects an abnormal sound based on the audio data acquired by the audio data acquisitor; and a hardware processor that determines whether the abnormal sound is such a sound that an operation of the apparatus to be judged should be restricted based on a subsequent secular change of the abnormal sound when the abnormal sound is detected by the abnormal sound detector, and restricts the operation of the apparatus to be judged when the hardware processor determines that the abnormal sound is such a sound that the operation of the apparatus to be judged should be restricted.