Abstract: An image forming apparatus includes an image forming portion configured to form an image on an intermediate transfer belt, a density sensor configured to measure a density of the image formed on the intermediate transfer belt, and a printer controller. On the intermediate transfer belt, a first test image and a third test image having different densities are alternately formed at different positions in a main scanning direction. At a position adjacent to the first test image in a sub-scanning direction, a second test image having a different density from that of the first test image is formed. At a position adjacent to the third test image in the sub-scanning direction, a fourth test image having a different density from that of the third test image is formed. The printer controller generates a gradation correction table based on a result of measurement of each test image by the density sensor.

Abstract: An image forming apparatus forms a first image by adjusting a photosensitive member potential to a first charging potential and adjusting a developing potential to a first developing potential, and forms a second image by adjusting the member potential to a second charging potential and adjusting the developing potential to a second developing potential, but not causing an exposure unit to expose a photosensitive member, and forms a third image by adjusting the developing potential to a third developing potential, but not causing a charging unit to charge the member and not causing the exposure unit to expose the member. The apparatus detects a streak image based on read data of the first, second and third images, and read data corresponding to a non-image region of the test sheet.

Abstract: In a case where a first mode in which a reader reads test patterns while sheets are fed to the reader by a document feeder is executed, an image forming apparatus forms a first test pattern on a first sheet and a second test pattern on a second sheet before the first test pattern on the first sheet placed on an original tray of the document feeder is read by the reader. In a case where a second mode in which the reader reads the test patterns on the sheets without feeding the sheets by the document feeder is executed, the apparatus forms the second test pattern after a reading of the first test pattern on the first sheet with the reader starts.

Abstract: A controller controls a first image forming unit and a second image forming unit to form a test image having a pattern. The test image is formed by the first image forming unit based on a first image forming condition in which an absolute value of a developing potential of a first developing sleeve is greater than an absolute value of a charging potential of a first photosensitive member. The pattern is formed by a second image forming unit based on a second image forming condition in which an absolute value of a developing potential of a second developing sleeve is smaller than an absolute value of a charging potential of a second photosensitive member. A controller controls a sensor to read the test image having the pattern.

Abstract: A controller controls a charging unit to charge a photosensitive member so that a surface potential of the photosensitive member is controlled to a first potential, controls an exposure unit to expose the photosensitive member so that a potential of an exposure region on the photosensitive member is controlled to a second potential, controls a surface potential of a developing sleeve of a developing unit to a third potential; and forms a test image on a sheet by controlling the photosensitive member, the charging unit, the exposure unit, and the developing unit. An absolute value of the first potential is larger than an absolute value of the second potential. An absolute value of the third potential is larger than the absolute value of the first potential.

Abstract: A reader can read an original. A printer can form an image on a sheet based on a read result of the reader. A controller can control the printer to form a test chart on the sheet, and control the reader to read the test chart. The test chart is used for detecting a causal part of a streak that occurs when an image is formed by the printer. The test chart has a pattern for obscuring an image defect occurring when the test chart is formed by the printer.

Abstract: An image forming apparatus includes an image forming portion configured to form an image on an intermediate transfer belt, a density sensor configured to measure a density of the image formed on the intermediate transfer belt, and a printer controller. On the intermediate transfer belt, a first test image and a third test image having different densities are alternately formed at different positions in a main scanning direction. At a position adjacent to the first test image in a sub-scanning direction, a second test image having a different density from that of the first test image is formed. At a position adjacent to the third test image in the sub-scanning direction, a fourth test image having a different density from that of the third test image is formed. The printer controller generates a gradation correction table based on a result of measurement of each test image by the density sensor.

Abstract: An image forming apparatus that enhances measurement accuracy of a pattern image and improves quality of a printed image. Light emitted from a light emission unit based on a first measurement condition is reflected from an image bearing member, and first information is generated based on a measurement result of the image bearing member. Second information is determined based on the first measurement condition, the first information, and a second measurement condition. Light is emitted based on the first measurement condition when a first measurement image is measured, and an image forming condition is generated based on a measurement result of the first measurement image and the first information. Light is emitted based on the second measurement condition when a second measurement image is measured, and the image forming condition is generated based on a measurement result of the second measurement image and the second information.

Abstract: An image forming apparatus including: a photosensitive member; a charging unit; an exposure unit; a developing unit; a transfer unit; and a controller configured to control the photosensitive member, the charging unit, the exposure unit, the developing unit, and the transfer unit to form a measurement image on the sheet, and acquire read data on the measurement image output from a reading device, wherein the measurement image includes a first measurement image and a second measurement image, wherein the controller forms the first measurement image based on a first image signal value and forms the second measurement image based on a second image signal value different from the first image signal value, and wherein the controller detects a streak included in the first measurement image or the second measurement image and determines an error based on a detection result.

Abstract: An image forming apparatus that enhances measurement accuracy of a pattern image and improves quality of a printed image. Light emitted from a light emission unit based on a first measurement condition is reflected from an image bearing member, and first information is generated based on a measurement result of the image bearing member. Second information is determined based on the first measurement condition, the first information, and a second measurement condition. Light is emitted based on the first measurement condition when a first measurement image is measured, and an image forming condition is generated based on a measurement result of the first measurement image and the first information. Light is emitted based on the second measurement condition when a second measurement image is measured, and the image forming condition is generated based on a measurement result of the second measurement image and the second information.

Abstract: Provided is an image forming apparatus capable of reducing the time required for calibration of an image forming condition. The image forming apparatus includes image forming portions configured to form images onto photosensitive drums, an intermediate transfer member onto which the images are sequentially transferred from the photosensitive drums, and a density detection sensor. The density detection sensor starts measuring a base surface density of the intermediate transfer member before a measurement image is formed on the intermediate transfer member. When a measurement start position of the base surface density reaches a transfer position of an image of an image forming portion located at the most upstream position in a rotation direction of the intermediate transfer member, the image forming apparatus causes the image forming portion to start forming the measurement image.

Abstract: An image forming apparatus forms a first image by adjusting a photosensitive member potential to a first charging potential and adjusting a developing potential to a first developing potential, and forms a second image by adjusting the member potential to a second charging potential, adjusting the developing potential to a second developing potential, but not causing an exposure unit to expose a photosensitive member, and forms a third image by adjusting the developing potential to a third developing potential, but not causing a charging unit to charge the member, and not causing the exposure unit to expose the member, and detects a streak image based on read data of the first, second and third images, and read data corresponding to a non-image region of the test sheet.

Abstract: To suppress an effect caused by a thermochromism phenomenon in which the color of an image whose color is to be measured changes depending on temperature and to accurately detect the color of the image whose color is to be measured. An image forming apparatus includes a color sensor that measures the color of an image fixed onto recording paper downstream of a fixing unit in a direction in which the recording paper is carried. The image forming apparatus corrects a result of the measurement of the color obtained by the color sensor in such a way as to suppress an effect due to the temperature of the recording paper at the time of the measurement of the color on the recording paper.

Abstract: A method for producing an electron-emitting device includes forming an electrode above a top surface of an insulation layer including the top surface and a side surface connected to the top surface; forming a first conductive film on the insulation layer so as to be separated from the electrode and extend from the top surface to the side surface; forming a second conductive film on the first conductive film so as to extend from the top surface to the side surface; and etching the second conductive film.