摘要:
A full color copying machine which includes intermediate transfer medium whereon toner images having respective color components, formed on a photoreceptor are transferred to form one color toner image, and a screen filter disposed so as to be freely inserted or removed in or from a path of exposure light, which filters the exposure light for exposing the photoreceptor into a pattern of lines. A plurality of color toner images obtained by executing a plurality of copying processes based on a plurality of exposures applied to an original document are superposed on the intermediate transfer medium to form a color toner image. The copying machine further includes a screen mode for inserting a screen filter into a path of exposure light and a normal mode for removing the screen filter from the path of exposure light. Thus, exposures intended for low density components and high density components in an original document image are respectively performed by the use of the different modes, or they are respectively performed by changing setting conditions of the screen filter in the screen mode. With these arrangements, efficient application of the exposure device and high quality of the copied images can be achieved.
摘要:
A method of cleaning a photosensitive member in an electrophotographic apparatus in which an electrophotographic operation is performed by charging the photosensitive member with a predetermined voltage, exposing the charged photosensitive member so as to form a latent image thereon and developing the latent image by use of toner, includes the steps of charging the photosensitive member with a half tone level voltage which is smaller than the predetermined voltage, and developing the charged photosensitive member by use of toner without exposing the charged photosensitive member, so as to form a uniform half tone toner image thereon. The cleaning method also includes the step of scraping off the toner of the uniform half tone toner image from the photosensitive member by a blade abutting thereto.
摘要:
A transfer roller device for transferring onto a copy paper sheet a full color toner image formed on an intermediate transfer belt. A rear-surface electrode roller disposed at the opposite side to a transfer roller with the intermediate transfer belt positioned in between, is divided into a plurality of cylinder members, and at least one of the cylinder members corresponding to the size of a copy paper sheet is separately connected to ground. With the arrangement, occurrence of an excess current through a portion of the intermediate transfer belt carrying no copy paper sheet thereon is eliminated, thereby preventing a filming phenomenon. In another arrangement, a plurality of rear-surface electrode rollers are disposed at respective positions associated with a plurality of respective copying speeds which are set according to copy paper sheets. Thus, a voltage to be applied between the transfer roller and the rear-surface electrode roller is maintained constant regardless of different copying speeds.
摘要:
A color balance adjusting apparatus is used for a full color copier in which an original image is illuminated by a light source; the illuminated image is exposed onto a photoreceptor to form electrostatic latent images corresponding to first, second and third colors for creating a color image; and each of the formed electrostatic latent images is developed into a visualized toner image. The color balance adjusting apparatus includes an infrared sensor for detecting toner density of the toner image formed with a toner having any one color of the first, second and third colors. The apparatus further includes automatic adjustment means which determines a relation of light intensity to toner density detected for one color by varying light intensity of said light source, and which determines optimal light intensity for the other two colors as predetermined functions of obtained optimal light intensity. Using this apparatus, automatic adjustment of the color balance for each copy mode can be effected in a short time with lesser consumption of electricity and supplies.
摘要:
A copying apparatus in which a screen for improving gradation characteristics of a copied image can be retractably projected into an optical path, including a device for setting, when the screen is placed in the optical path and retracted from the optical path, a developing voltage to a first value and a second value, respectively such that the first value is lower than the second value.
摘要:
An electrophotographic copying apparatus comprises a photosensitive member (4) exposed by light reflected from an original to form an image of the original thereon, mechanism (13) for developing the image on the photosensitive member with toner (9, 10, 11, 12) to produce a toner image corresponding the image mechanism (24) for transferring the toner image onto a transfer material, mechanism (26) for fixing the toner image transferred on the transfer material, mechanism (27) for producing a signal which represents that high surface glossiness of the image copy is required, and mechanism (31, 32) for feeding the transfer material in a first path when the signal is produced, the transfer material being fixed fully, and for feeding the transfer material in a second path shorter than the first path when the signal is not produced.
摘要:
A cleaning structure of an image forming device comprises an image retainer, a cleaning blade supported to touch a moving surface of the image retainer, a cleaning roller supported to touch the moving surface of the image retainer in a position downstream from the position of the cleaning blade. The cleaning roller comprises a roller shaft, a roller base layer and a fluorocarbon polymer layer which is excellent in noncohesiveness and slip property.
摘要:
A high density detecting toner pattern is formed on a photosensitive body and a high density correction is effected by comparing a value detected by a reflection sensor with a high density reference value so as to maintain an image density at a specific level. An image density correcting section adopts a result of the preceding high density correction as the high density reference value, and compares the same with a result of a current high density correction. The image density correcting section effects the half-tone density correction only when a difference reaches or exceeds a preset difference reference value by forming a half-tone density detecting toner pattern on the photosensitive body and comparing a value detected by the reflection sensor with a half-tone reference value. Consequently, it has become possible to provide an image forming apparatus which can maintain a density output of an entire image at a specific level for any kind of images including solid, line, and half-tone, etc. while shortening a time required for the density correction and reducing a quantity of toner consumed for the density correction.
摘要:
A test patch image is formed and the density thereof is detected to maintain the image quality at a constant level. One of the image forming conditions, for example, the developing bias voltage of the developing unit inside the image forming apparatus that serves as a density controller, and is controlled in accordance with the detection result. Here, a humidity sensor for detecting the environmental change, that is, the humidity, is provided inside the apparatus, and the reference value of the toner mixing ratio is changed and corrected while the developing unit is operating when the humidity sensor detects a change in humidity. However, the toner mixing ratio is maintained and neither changed nor corrected when the density of the test patch image remains at the same level, so that the developing bias voltage is not corrected. Consequently, the correction of the toner mixing ratio is neither changed nor corrected in response to the change in humidity alone, thereby making it possible to maintain a stable image quality state.
摘要:
An object of the present invention is to obtain, in an accurate and stable manner, an image density at a tone rise point in a low-density region in order to form a stable image. At the time of execution of an image density correction in an image forming apparatus which employs an electrophotographic process, a toner pattern of a plurality of toner patches is formed on the basis of a reference density correction table which specifies an image density output value used for correction of an image density input value, the density of the toner patches is detected by a density detecting sensor, points corresponding to a plurality of image densities in a low-density region, detected above a predetermined level of sensitivity of the sensor, are plotted thereby to find a linear interpolation formula, an image density in the low-density region below the predetermined level of sensitivity of the density detecting sensor is interpolated with the linear interpolation formula, a comparison between the reference density correction table and a result of the interpolation is made so as to correct the image density output value, and a correction table as a post-modification correction table is prepared. An actual image is prepared using the correction table.