In a sheet-processing apparatus, a controller controls a conveying guide to change over a sheet-conveying path of sheets that are ejected without stapling them to a sheet-processing conveying path based on predetermined sheet-conveying path selection information when judging that a non-stapling mode in which the sheet stapling processing is not performed on a first type of sheets follows a stapling mode in which the sheet-stapling processing is performed on a second type of sheets. The first type of sheets, which are not to be stapled, conveyed on the sheet-processing conveying path waits on a waiting portion in the non-processing mode while in the processing mode, a sheet-processing portion performs the sheet processing on the second type of sheets.

An image forming apparatus includes a feeder including a tray and a pickup member, a size determiner, a sheet type setter, and a controller. The tray stacks a sheet thereon, and the pickup member feeds a contacted sheet. The feeder switches between a first state where the pickup member and the stacked sheet are in contact and a second state where the pickup member and the stacked sheet are separate. The size determiner determines a stacked sheet size. The sheet type setter sets a stacked sheet type. Where the type of the set sheet is a first type, the feeder switches from the second state to the first state when the size of the sheet is determined. Where the type of the set sheet is a second type, the feeder refrains from switching from the second state to the first state even when the size of the sheet is determined.

A sheet discriminator, which can be included in an image forming apparatus, includes an optical information detector, a sheet distinguisher, and a sheet thickness detector. The optical information detector includes a light emitter to emit light to a recording medium and a light receiver to receive the light and detects information of the recording medium. The sheet distinguisher distinguishes a type of the recording medium based on the information detected by the optical information detector. The sheet thickness detector includes a displacement gauge to sandwich the recording medium with an opposing member disposed facing the displacement gauge and to move from an initial position thereof and a displacement detector to detect an amount of displacement of the displacement gauge. The sheet thickness detector detects a thickness of the recording medium based on detection results obtained by the displacement detector.

A fixing device includes a detecting portion that detects a load applied to a driving portion configured to drive a fixing portion configured to fix an image formed on a medium, an identifying portion that identifies a type of the medium from a result of detection performed by the detecting portion, and a setting portion that sets a threshold with reference to which the identifying portion identifies the type of the medium. The threshold is set for each of different temperatures detected by a temperature detecting portion that detects a temperature of the fixing portion or for each predetermined number of media on which images are fixed.

A determination device includes a processor that is used for determining first paper having a surface on which an embossing process is performed and second paper having a surface on which the embossing process is not performed, a light source that irradiates a surface of paper with light, a light detector that receives the light transmitted through the paper and that detects a light transmittance, an ultrasonic transmitter that transmits an ultrasonic wave to the surface of the paper, and an ultrasonic receiver that receives the ultrasonic wave transmitted through the paper and that detects an ultrasonic transmittance, in which the processor is configured to: use an index that is stored in advance in a storage device and that indicates a correlation between the light transmittance and the ultrasonic transmittance in the second paper, and determine whether or not the paper is the first paper or the second paper according to whether or not the light transmittance and the ultrasonic transmittance, which are detected from the paper, are apart from the index by a predetermined threshold value or more.

A sheet discriminator, which can be included in an image forming apparatus, includes an optical information detector, a sheet distinguisher, and a sheet thickness detector. The optical information detector includes a light emitter to emit light to a recording medium and a light receiver to receive the light and detects information of the recording medium. The sheet distinguisher distinguishes a type of the recording medium based on the information detected by the optical information detector. The sheet thickness detector includes a displacement gauge to sandwich the recording medium with an opposing member disposed facing the displacement gauge and to move from an initial position thereof and a displacement detector to detect an amount of displacement of the displacement gauge. The sheet thickness detector detects a thickness of the recording medium based on detection results obtained by the displacement detector.

An image forming apparatus includes an image forming unit, a transmission unit, a reception unit, a control unit configured to obtain a time period until the reception unit receives a first ultrasonic wave via a first recording material and an amplitude value thereof at a reference temperature, obtain a time period until the reception unit receives a second ultrasonic wave via a second recording material and an amplitude value thereof at a different temperature, control an image formation condition for forming the image on the first recording material on the basis of the amplitude value of the first ultrasonic wave, obtain a difference time period between reception of the first and second ultrasonic waves, and control an image formation condition for forming the image on the second recording material on the basis of the difference time period and the amplitude value of the second ultrasonic wave.

A transfer device includes an image bearer and a transfer rotator. The transfer device further includes an adjuster including a rotatable cam and an opposed member opposed to the cam. The cam alternately contacts and separates the transfer rotator against and from the image bearer, having a continuous sloped surface with a plurality of positions, each position to contact the opposed member to obtain a different amount of separation between the image bearer and the transfer rotator. The transfer device further includes a controller to control the adjuster to adjust the amount of separation between the transfer rotator and the image bearer according to thickness or type of the recording medium when the recording medium starts to enter the transfer nip.

An optical sensor including an abutment part configured to abut one edge of an object to be measured, a wall extending along a side of the object to be measured and having a first opening to pass light emitted to the object to be measured, and a first concave portion formed between the first opening and the abutment part on a side of the wall to position the object to be measured. A paper-type discrimination device including the optical sensor, and a controller configured to discriminate a paper type of the object using the reflection light from the object measured by the optical sensor. An image forming apparatus including the optical sensor or the paper-type discrimination device.

A print setting controller decides whether a combination of a sheet size and a sheet type specified for print setting is included in a combination table. When the combination of the sheet size and the sheet type specified for the print setting is included in the combination table, a controller executes a print job according to the print setting. When the combination of the sheet size and the sheet type specified for the print setting is not included in the combination table, the print setting controller selects a sheet type appropriate for the sheet size specified as the print setting, from the combination table, and changes the sheet type thus far designated to the selected sheet type. A display controller causes a display device to display a message to the effect that the sheet type has been changed.