The present sheet conveying apparatus includes: a resist roller pair that corrects skew of a sheet conveyed from a sheet supplying unit; and a guide portion disposed at an upstream side relative to the resist roller pair in a sheet conveying direction, the guide portion including a first guide and a second guide disposed opposite to the first guide with a sheet conveying path therebetween, the second guide being located at a projection side of a curved portion formed in the sheet when a tip of the sheet is conveyed to a nip portion of the resist roller pair that is stopped, the second guide being divided into a plurality of divided guides in an axial direction of the resist roller pair, a flexible film being disposed to cover at least a portion of a space between the plurality of divided guides.

An image forming apparatus includes a transfer portion, a fixing portion, a sensor, a duct, and an airflow generation portion. The transfer portion transfers a toner image to a sheet. The fixing portion fixes the toner image transferred to the sheet by the transfer portion on the sheet. The sensor senses the sheet on a downstream side of the transfer portion in a conveyance direction of the sheet and an upstream side of the fixing portion in the conveyance direction. The duct extends from an air intake port to an air blowing port. The air intake port is open on an upper surface of the image forming apparatus. The air blowing port is open toward the sensor. The airflow generation portion generates airflow that moves in the duct from the air intake port to the air blowing port.

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.

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.

An image reading device includes a conveyance path along which a recording medium is conveyed, a colorimeter that reads an image to be subjected to colorimetry, the image being recorded on the recording medium conveyed on the conveyance path, a detector that detects a position of the recording medium in a direction intersecting a conveyance direction of the recording medium; and a first hardware processor that controls the colorimeter so as to read the image to be subjected to colorimetry on a basis of a detection result by the detector.

An image forming apparatus includes an image forming unit configured to form measurement images used for density correction at different timings using pseudo halftone processing patterns and a density detection sensor for detecting density of an object to be detected on an optical path including the formed measurement image. Further, the image forming apparatus includes a shutter which is arranged in the optical path between a density detection sensor and the measurement image, changed, by a motor, to a closed state in which a detecting surface of the density detection sensor is closed when the measurement image is not detected, and changed to an open state in which the detecting surface of the density detection sensor is opened when the measurement image is detected. Further, the image forming apparatus includes a controller which changes an image forming condition based on the detection result of the density detection sensor.

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.

An image forming apparatus comprises an image forming unit configured to form measurement images used for density correction at different timing using pseudo halftone processing pattern and a density detection sensor for detecting density of an object to be detected on an optical path including the measurement image formed. Further, the image forming apparatus comprises a shutter which is arranged on the optical path between a density detection sensor and the measurement image, changed, by a motor, to a closed state in which a detecting surface of the density detection sensor is closed when the measurement image is not detected and changed to an open state in which the detecting surface of the density detection sensor is opened when the measurement image is detected. Further, the image forming apparatus comprises a controller which changes an image forming condition based on detection result of the density detection sensor.

An electrophotographic image forming apparatus includes: a replacement detector that detects that a toner bottle has been replaced; a developer that develops an electrostatic latent image by using a toner supplied from the toner bottle and stored; a fog detector that detects a fog amount; and a determiner that determines whether or not the detected fog amount continuously exceeds a predetermined threshold value in a state where a toner supplied from a toner bottle before replacement and a toner supplied from a toner bottle after replacement are mixed in the developer.

A sheet characteristic detection device includes, a nipper that nips a recording medium; a sheet thickness detection sensor that detects displacement of the recording medium in a thickness direction at the nipper; and a hardware processor that calculates a thickness of the recording medium based on a detection value detected by the sheet thickness detection sensor. The hardware processor corrects the detection value detected by the sheet thickness detection sensor or the thickness according to a length of the recording medium in a width direction orthogonal to a conveyance direction or the length of a portion of the recording medium in contact with the nipper in the width direction, and acquires the thickness of the recording medium.