Abstract: A developing device includes first-third sections, a developing roller, a partitioning wall and a toner concentration detector. The first-third sections have first-third screw augers respectively. The partitioning wall isolates the third section from the first section and the second section. A supply opening is formed in a portion of the partitioning wall opposing the first section. A toner concentration detector is disposed in the third section. The first screw auger conveys developer including toner to the developing roller, into the third section via the supply opening, and into the second section. The second screw auger conveys developer accommodated in the second section into the third section. The third screw auger conveys developer accommodated in the third section into the first section. Toner is replenished into the third section based on a detection result by the toner concentration detector.

Abstract: To ensure stable feed of transfer material when a paper back vacuuming feed mechanism is employed in the path from a transfer section to a fixing section in an image forming apparatus, the image forming apparatus is such that the transfer section is arranged on the upper surface of the intermediate transfer unit; a transfer material feed apparatus is provided for vacuum feeding transfer material from the transfer section to the fixing apparatus; a guide tilted by a predetermined angle downward of the transfer material feed surface is provided at the outlet of the fixing apparatus of the transfer material feed apparatus; the nip portion of a fixing roller pair of the fixing apparatus is positioned downward of the extension line of the guide; and the tangent with respect to the nip portion of the fixing roller is tilted by a predetermined angle downward of the transfer material feed surface.

Abstract: An image forming apparatus includes: a first image forming unit having a first printing section for forming a first image on the paper; a second image forming unit having a second printing section for forming a second image on the paper; and a paper conveying unit for conveying the paper from the first image forming unit to the second image forming unit. Accordingly, two kinds of image can be formed employing one image forming apparatus. The first image and the second image may be formed using the same recording material (toner) or different recording materials (toners).

Abstract: A cleaning device is disposed substantially vertical above a photosensitive drum for the purpose of constructing a compact electrophotographic printer. The cleaning device includes a housing that accommodates an auxiliary toner conveying part and a sheet-like resilient member. A cleaning brush is also disposed in the housing so that a gap of 1-3 mm is formed between the cleaning brush and the auxiliary toner conveying part and resilient member. During an image forming operation, toner accumulates between the cleaning blade and the cleaning brush and is conveyed upward through the gap between the cleaning brush and the auxiliary toner conveying part and resilient member. The toner drops onto the cleaning brush near the top thereof and is conveyed by the cleaning brush to a screw. The screw discharges the toner from the cleaning device.

Abstract: A fixing device wherein supposing that the total load given to the heating roller and the pressure roller is W (kgf) and the area of the pressure contact portion of the heating roller with respect to the pressure roller (nip area) is S (cm2), the nip pressure (=W/S) is 2.7 kgf/cm2 or more and the length of the pressure contact portion in the direction parallel to the direction of conveyance of the recording material is defined to be 14 mm or more.

Abstract: To ensure stable feed of transfer material when a paper back vacuuming feed mechanism is employed in the path from a transfer section to a fixing section, in an image forming apparatus, the image forming apparatus is such that the transfer section is arranged on the upper surface of the intermediate transfer unit; a transfer material feed apparatus is provided for vacuum feeding transfer material from the transfer section to the fixing apparatus; a guide tilted by a predetermined angle downward of the transfer material feed surface is provided at the outlet of the fixing apparatus of the transfer material feed apparatus; the nip portion of a fixing roller pair of the fixing apparatus is positioned downward of the extension line of the guide; and the tangent with respect to the nip portion of the fixing roller is tilted by a predetermined angle downward of the transfer material feed surface.

Abstract: An image forming apparatus includes: a first image forming unit having a first printing section for forming a first image on the paper; a second image forming unit having a second printing section for forming a second image on the paper; and a paper conveying unit for conveying the paper from the first image forming unit to the second image forming unit. Accordingly, two kinds of image can be formed employing one image forming apparatus. The first image and the second image may be formed using the same recording material (toner) or different recording materials (toners).

Abstract: In a corona discharging apparatus for use in an electrophotographic printing apparatus, a wire spring-like member having the torque limiter function is used for the cleaning member to conduct the power transmission of the screw shaft, and by releasing the load larger than a predetermined value, the deformation of the gear and deviation of the shaft are eliminated, and the lock of the motor is prevented from being generated.

Abstract: A toner cartridge includes a container for containing toner of a volume of 2500 cm3 or more. The container defines an opening portion, a cap is fixed to the opening portion of the container, and the cap defines a first semicircle opening portion. A film covers and seals the first semicircle opening portion of the cap. A shutter is rotatably disposed on the cap and the shutter defines a second semicircle opening portion capable of corresponding to the first semicircle opening portion of the cap, the shutter having a diameter of 70 mm or above.

Abstract: In a developing system containing a combination of forward-rotating and a backward-rotating developing rollers, a steady quantity of developing agent should be supplied to the developing rollers for high-quality printed images. This requirement can be satisfied by placing a doctor blade between an intersection point, where a line connecting the central axis of one of the developing rollers and its polarity reversing position meets a line connecting the central axis of the other of the developing rollers and its polarity reversing position, and the developing roller pair.

Abstract: A fixing device has a web unit with a housing having two shaft members in parallel with each other, the housing defining a through hole on each of two lateral sides of the housing. The web unit also has a web member windably supported by the two shaft members, and a handle having two protrusion protruded from a lateral surface of the housing to outside of the housing. Each of the two protrusions defines a first width and a second width larger than the first width. The fixing device also has a fixing device frame to be detachably disposed to the web unit. The fixing device frame has a guiding groove with a groove through which the two protrusions are guided on the basis of the first width, and a guiding portion at an end of the groove to allow the two protrusions to be changed from the first width to the second width. The attachment or detachment of the web unit to or from the fixing device frame is regulated corresponding to a position of the handle with respect to the housing.

Abstract: An image forming apparatus includes a developing unit having a photoreceptor, for making an electrostatic latent image on a surface of the photoreceptor visible as a toner image. A toner hopper stores toner to be supplied to the developing unit and a cleaning device removes and recovers the toner remaining on the surface of the photoreceptor after the toner image has been transferred onto a recording material. A toner transporting passage is connected between the cleaning device and the toner hopper, through which the toner recovered by the cleaning device is returned to the toner hopper. A toner exhausting port is disposed at a part of the toner transporting passage, from which the toner being returned from the cleaning device side is exhausted outside the toner transporting passage. An opening and closing member selectively opens or closes the toner exhausting port, wherein an inner diameter of the toner exhausting port is made larger than that of the toner transporting passage.

Abstract: A uniform image is obtained by matching the sliding friction force, the moving speed and the developing agent in a developing region of two developing rollers and an electric characteristic of a photosensitive body used for image development. Two developing rollers rotating in directions opposite to each other are used, the moving direction of the first developing roller being opposite to the moving direction of the photosensitive body, and a circumferential speed ratio of a circumferential speed of the first developing roller to a circumferential speed of the photosensitive body is within a rage of 0.5 to 2.5; and the moving direction of the second developing roller is equal to the moving direction of the photosensitive body, and a circumferential speed ratio of a circumferential speed of the second developing roller to a circumferential speed of the photosensitive body is within a range of 1.5 to 3.5.

Abstract: A predetermined mathematical formula, which defines an occurrence degree of an image defect where the toner layer is thinned or no toner image is formed, is set up, which is valid for a developing device including a reverse turn developer carrier and a forward turn developer carrier. A difference between the total sum A of the values by the above formula showing the occurrence degree of the image defect on the forward turn developing roller and the total sum B of the values by the above formula showing the occurrence degree on the reverse turn developing roller, i.e., (A-B), is selected within a range of -0.56 to +0.5.