A recording material determination apparatus includes a transmission unit, a reception unit, and a determination unit. The transmission unit transmits an ultrasonic wave to a recording material. The reception unit vibrates when the reception unit receives the ultrasonic wave having been transmitted from the transmission unit and having passed through the recording material, and outputs a signal corresponding to a vibration state. The determination unit determines a basis weight of the recording material in accordance with the signal output from the reception unit. A resonance frequency of the reception unit differs from a resonance frequency of the transmission unit, and the reception unit is capable of receiving a sound wave in an ultrasonic range and a sound wave in an audible range.

An image forming apparatus includes an accommodating portion, an image forming unit, a skew correcting portion, a conveyance unit, a detection unit, a re-conveyance unit, and a control unit. The control unit controls the re-conveyance unit such that the re-conveyance unit stops a sheet in the second conveyance path temporarily and starts to convey the sheet at a first timing after a second timing and before a third timing, where the second timing is a timing such that if the sheet is started to convey to the first conveyance path at the second timing, the conveyance unit decelerates the conveyance speed when the sheet reaches to the detection unit, and the third timing is a timing such that if the sheet is started to convey to the first conveyance path at the third timing, the conveyance unit decelerates the conveyance speed when the sheet reaches to the skew correcting portion.

The image forming apparatus includes a main assembly, a replacement unit detachably mounted on the main assembly, an identification unit configured to identify whether the replacement unit is a first unit mounted in advance in a shipment state of the image forming apparatus or is a second unit after replacement, a common signal line configured to transmit a signal from the identification unit and another signal; a memory unit mounted on the main assembly and configured to store control information for the first unit, and a control unit configured to control the first unit based on the control information of the first unit, wherein the control unit is switchable between an identification mode and a normal operation mode, and wherein the control unit switches control information of the replacement unit mounted on the main assembly depending on whether the replacement unit is the first unit or the second unit.

A recording material determination apparatus includes a transmission unit, a reception unit, and a determination unit. The transmission unit transmits an ultrasonic wave to a recording material. The reception unit vibrates when the reception unit receives the ultrasonic wave having been transmitted from the transmission unit and having passed through the recording material, and outputs a signal corresponding to a vibration state. The determination unit determines a basis weight of the recording material in accordance with the signal output from the reception unit. A resonance frequency of the reception unit differs from a resonance frequency of the transmission unit, and the reception unit is capable of receiving a sound wave in an ultrasonic range and a sound wave in an audible range.

A recording material determination apparatus includes a transmission unit, a reception unit, and a determination unit. The transmission unit transmits an ultrasonic wave to a recording material. The reception unit vibrates when the reception unit receives the ultrasonic wave having been transmitted from the transmission unit and having passed through the recording material, and outputs a signal corresponding to a vibration state. The determination unit determines a basis weight of the recording material in accordance with the signal output from the reception unit. A resonance frequency of the reception unit differs from a resonance frequency of the transmission unit, and the reception unit is capable of receiving a sound wave in an ultrasonic range and a sound wave in an audible range.

A protection member is arranged such that the distance from an opening plane of a reception guide to the center of the protection member is half of the distance from the opening plane of the reception guide to the surface of a reception vibration member. In other words, the arrangement position of the protection member is in the center between the opening plane of the reception guide and the surface of the reception vibration member. Accordingly, even if a protection member is arranged, a transmission coefficient is obtained that is equal to a transmission coefficient in the case where no protection member is present.

The image forming apparatus includes a main assembly, a replacement unit detachably mounted on the main assembly, an identification unit configured to identify whether the replacement unit is a first unit mounted in advance in a shipment state of the image forming apparatus or is a second unit after replacement, a common signal line configured to transmit a signal from the identification unit and another signal; a memory unit mounted on the main assembly and configured to store control information for the first unit, and a control unit configured to control the first unit based on the control information of the first unit, wherein the control unit is switchable between an identification mode and a normal operation mode, and wherein the control unit switches control information of the replacement unit mounted on the main assembly depending on whether the replacement unit is the first unit or the second unit.

A recording material determination apparatus includes a transmission unit, a reception unit, and a determination unit. The transmission unit transmits an ultrasonic wave to a recording material. The reception unit vibrates when the reception unit receives the ultrasonic wave having been transmitted from the transmission unit and having passed through the recording material, and outputs a signal corresponding to a vibration state. The determination unit determines a basis weight of the recording material in accordance with the signal output from the reception unit. A resonance frequency of the reception unit differs from a resonance frequency of the transmission unit, and the reception unit is capable of receiving a sound wave in an ultrasonic range and a sound wave in an audible range.

A document size detection device includes: a light source that irradiates a document placed on placing means with scanning light via the placing means; a reading unit that receives reflection light from the document via the placing means to acquire image data of the document; and circuitry to set an illumination depth of the scanning light at a size detection time when the size is detected, shallower than an illumination depth of the scanning light at an image reading time when an image of the document is read, and detects, at the size detection time, the size based on a difference between first image data acquired in a state in which the scanning light is switched off and second image data acquired in a state in which the scanning light is switched on.

The edge pixel determining unit (21) determines edge pixels in an input image, and the property determining unit (23) determines an edge pixel of a ruled-line edge among the determined edge pixels. The output image processing unit (12) performs predetermined image processing for the edge pixels so as to make a toner consumption amount of the edge pixel of the ruled-line edge smaller than a toner consumption amount of an edge pixel other than the edge pixel of the ruled-line edge.