JP4047370B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a color copying machine, a color printer, or a color facsimile that performs photoconductor superposition or has an intermediate transfer member.

  As a typical conventional color image forming apparatus, a photosensitive drum that forms a latent image and a transfer drum that holds a transfer paper and transfers a toner image on the photosensitive member, or a photosensitive drum is used. A method in which a plurality of toners are superimposed and transferred onto a transfer sheet, or toner images of respective colors formed on a photosensitive drum are sequentially superimposed and transferred, for example, to the same position on an intermediate transfer belt, and the transferred image is transferred. A method of transferring to paper has been put into practical use. In the method using a transfer drum, the transfer paper must be held electrostatically or mechanically on the transfer drum, so it is difficult to use small-size paper such as postcards or thick paper as transfer paper. It is not so-called paper-free. Also, with the method of mechanically holding the leading edge of the transfer paper, the image cannot be transferred to the entire transfer paper. Furthermore, a device that can use A4 size transfer paper as a transfer drum requires a drum diameter of about φ100 mm or more, and a device that can use A3 size transfer paper requires a drum diameter of about φ150 mm or more. Was inviting.

  On the other hand, the photosensitive belt superposition method and the intermediate transfer belt method also have paper-free properties that allow postcards and thick paper to be used as transfer paper as the transfer method. Depending on the configuration of the transfer belt, the device body can be downsized. It is also possible to do. However, as a whole conveying system, the present inventors have not yet known a miniaturized color apparatus that takes into consideration the handling of thick paper and jam handling. In particular, with regard to handling thick paper, the demand for thick paper on transfer paper of color devices has reached a considerable thickness in the use of posters, Christmas cards, etc., and the basis weight of a normal monochrome laser printer is 157 g / m2. On the other hand, since the basis weight is required up to 250 g / m 2, it was difficult to cope with it.

In the technique disclosed in Patent Document 1, an intermediate transfer belt is used to reduce the size of the transfer paper conveyance path by using an upper conveyance type. However, as the conveyance path, a paper feed cassette unit or a paper discharge stack unit protrudes. Therefore, the size of the entire apparatus main body cannot always be achieved. Further, in the technique disclosed in Patent Document 2, the process cartridge is held on the upper body of the clamshell type and the transfer paper transport path can be opened by the color overlaid method on the photoconductor, and can be operated from one side. However, there is no contrivance for cardboard.
JP-A-2-294673 JP-A-3-271754

  In view of the above-described conventional problems, the present invention achieves paper-free properties such that postcards and cardboard can be used as transfer paper in the entire conveyance quality of the apparatus main body, and achieves downsizing of the apparatus main body, and processing of transfer paper An object of the present invention is to provide an image forming apparatus with improved operability and high image quality.

  An image forming apparatus according to a first aspect of the present invention includes an apparatus main body, an intermediate transfer belt that is stretched by at least two rollers and is rotatable with respect to the apparatus main body, and the apparatus main body. The intermediate transfer belt is configured to be rotatable by rotating the cover and to a frame supported by the apparatus main body. The cover is configured to be detachable, the cover is configured to hold the intermediate transfer belt, and is configured to be rotatable to a position where a surface of the intermediate transfer belt facing the cover faces downward, and the device is configured by a spring. It is configured to be able to maintain an open state with respect to the main body.

  According to a second aspect of the present invention, the intermediate transfer belt is inclined with respect to a horizontal direction in a state where the cover holds the intermediate transfer belt from below.

  According to the third aspect of the present invention, the apparatus main body includes a plurality of units that are detachable from the apparatus main body and each include a toner containing portion and a developing roller.

  According to a fourth aspect of the present invention, there is provided a process cartridge that includes the intermediate transfer belt and is rotatably supported between an operating position and a retracted position, and the cover has a closed position and an open position with respect to the apparatus main body. And an opening for attaching and detaching the plurality of units is formed by rotating the cover and the process cartridge from the closed position and the operating position, respectively. To do.

  According to the fifth aspect of the present invention, there is provided a sheet feeding cassette on the lower side of the apparatus main body, and a rotation fulcrum of the cover is provided on the sheet feeding port side of the sheet feeding cassette.

  According to the sixth aspect of the present invention, there is a manual paper feed unit that is connected to the transfer paper transport path and transports the manual paper feed unit. The manual paper feed unit is housed in a use position for feeding paper and the apparatus main body. The manual sheet feeding unit is housed in substantially parallel to the intermediate transfer belt when in the unused position.

  According to the seventh aspect of the present invention, the manual paper feed unit is provided so that an angle between a paper entering direction of the manual paper feed unit and the direction of the transfer paper conveyance path forms an acute angle when the manual paper feed unit is in the use position. It is characterized by that.

  According to the eighth aspect of the present invention, the manual sheet feeding unit is embedded in the cover when in the unused position.

  An image forming apparatus according to the present invention includes an apparatus main body, an intermediate transfer belt that is stretched by at least two rollers and is rotatable with respect to the apparatus main body, and a cover that is rotatable with respect to the apparatus main body. The intermediate transfer belt is configured to be rotatable when the cover is rotated, and is configured to be detachable from a frame supported by the apparatus main body. The cover is configured to hold the intermediate transfer belt and to be rotatable to a position where a surface of the intermediate transfer belt facing the cover faces downward, and is opened to the apparatus main body by a spring. Since it is configured so that it can be maintained, the jam handling operation is easy to understand, and it can be operated safely without worrying about the fall of the opened cover. Since only jam processing without the operation can be, there is an effect that there is no problem such as toner drop.

  An embodiment of a color image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of a color image forming apparatus of the present invention. In FIG. 1, reference numeral 1 denotes a flexible belt-like photosensitive member (hereinafter referred to as a photosensitive member or a photosensitive belt) that is a belt-like image carrier, and the photosensitive belt 1 is installed between rotating rollers 2 and 3. Then, it is rotated and conveyed in the clockwise direction in the figure by driving the rotation rollers 2 and 3. 4 is a charging charger as a charging means, 5 is a laser writing system unit as an image exposure means, 6 is three developing means containing yellow, magenta and cyan color developers, that is, a rotary color developing device, and 7 is a color developing device. This is a black developing device that is a developing unit that contains a black developer provided separately from the developing device 6.

  The laser writing system unit 5 has a laser beam generated by a semiconductor laser (not shown) rotated and scanned by a polygon mirror 5B rotated by a drive motor 5A, an optical path is bent by a mirror through an fθ lens 5C, and charged in advance. It is exposed on the circumference of the photosensitive belt 1 uniformly charged by the charging charger 4 to form an electrostatic latent image. For this reason, the laser writing system unit 5 is housed in a holding housing having a slit-shaped exposure opening on the upper surface and is incorporated in the apparatus main body. A bottom plate (not shown) is provided above the paper feed cassette 17 and below the laser writing system unit 5. The laser writing system unit 5 is incorporated therein, and the side plate of the apparatus main body is attached in the roller axis direction to support each unit. It is provided on the left and right sides and assembled to the bottom plate. In addition to the laser writing system unit 5 shown in the figure, an optical system in which a light emitting unit and a convergent light transmission body are integrated is also used. The charging charger 4, the laser writing light 5D, and the photoconductor cleaning blade 15A are provided on the rotating roller 2 side on which the photoconductor belt 1 is installed.

  The color developing unit 6 and the black developing unit 7 are each provided with a developing roller that comes close to or in contact with the photosensitive belt 1 at a predetermined position, and the latent image on the photosensitive belt 1 is developed by non-contact development or contact development. It has a function of imaging. Reference numeral 10 denotes an intermediate transfer belt as an intermediate transfer member. The intermediate transfer belt 10 is disposed between the rotating rollers 11 and 12 so as to be inclined, and is driven counterclockwise in the drawing by driving the rotating rollers 11 and 12. Rotated and conveyed. The lower inclined belt surface of the intermediate transfer belt 10 is in contact with the photosensitive belt 1 and the intermediate transfer belt 10 at the part of the rotating roller 3, and the first visible image on the photosensitive belt 1 is intermediate. The image is transferred onto the intermediate transfer belt 10 by the bias brush 13 provided in the transfer belt (primary transfer position), and by repeating the same process, the second image, the third image, The fourth visible images are superimposed on the intermediate transfer belt 10 and transferred so as not to cause positional deviation. A transfer roller 14 serving as a secondary transfer member is provided on the rotation roller 11 of the intermediate transfer belt 10 so as to be in contact with and away from the intermediate transfer belt 10. The distance on the intermediate transfer belt 10 from the primary transfer position to the secondary transfer position is set to be equal to or longer than the maximum image output length.

  In the figure, reference numeral 15 denotes a waste toner collecting container including a cleaning blade 15A for the photosensitive belt 1, 16 is a cleaning device for the intermediate transfer belt 10, and the blade 16A of the intermediate transfer belt cleaning device 16 is the intermediate transfer belt 10 during image formation. The surface of the intermediate transfer belt 10 is kept in contact with the surface of the intermediate transfer belt 10 as shown in the figure only during cleaning after the secondary image transfer.

  FIG. 2 shows the internal configuration of the color and black developing units 6 and 7, and FIG. 3 is a perspective view of the color developing unit 6. The rotary type color developing device 6 is provided with a casing 21 which is a rotating body so as to be rotatable around a rotation center O, and the casing 21 can be rotated in the clockwise direction in the drawing by driving a drive mechanism (not shown). It has become. The casing 21 integrally holds yellow, magenta, and cyan color developing units 22 (-Y, M, C). The color developing units 22 (-Y, M, C) of the respective colors take the same form and the same operation.

  The photosensitive belt 1 installed between the rotating rollers 2 and 3 is provided with a backup roller 35 so as to push one of the two extended portions between the rotating rollers 2 and 3 outward, and the upper belt. The black developing device 7 is arranged at the upper part and the color developing device 6 is arranged at the lower part so that the surface is vertical and the lower belt surface is slightly inclined. That is, since the intermediate transfer belt 10 is inclined and the photosensitive belt 1 is substantially vertical, the waste toner collecting container 15 can secure a certain capacity space.

  At the developing position in the color developing unit 6, the developing roller 23 is disposed to face the photosensitive belt 1 so that the developing roller 23 rotates in the same direction as the moving direction of the photosensitive belt 1 with a predetermined linear velocity ratio. Is done. Below the developing roller 23, a supply roller 25 made of an elastic material such as polyurethane foam slides on the rubbing portion with the developing roller 23 and rotates with a predetermined linear velocity ratio in the same direction as the developing roller 23. Is provided. A developing blade 26 made of a thin plate having a spring property such as stainless steel is provided on the downstream side in the rotation direction of the supply roller 25 so that one end thereof is in contact with the developing roller 23.

  As shown in FIG. 3, a toner storage unit 29 is provided on the front side of the color developing unit 6, and the screw-like first toner transport member 27 is disposed behind the color developing unit 6 from the toner storage unit 29. Arranged in parallel with the developing roller 23 and the supply roller 25 up to the side plate of the developing unit 22, the toner is conveyed from the front side to the rear side in the figure. Then, it is linked with the developing roller 23 and the supply roller 25 and rotates with them at a predetermined linear velocity ratio. A part of the partition plate 24 is disposed so as to be in contact with the supply roller 25, and a toner transport space surrounding the first toner transport member 27 is formed by the developing roller 23, the supply roller 25, and the like. The toner supplied onto the supply roller 25 is supplied to the surface of the developing roller 23 by the supply roller 25 and charged, and is carried on the surface of the developing roller 23. The toner carried on the surface of the developing roller 23 is thinned by the developing blade 26 to develop the electrostatic latent image formed on the surface of the photoreceptor belt 1.

  By the way, the toner that has not been used in the developing process is conveyed by the first toner conveying member 27 to the rear end portion of the color developing device 6 on the side facing the toner containing portion 29, and the axial direction of the developing roller 23 and the supply roller 25. The toner reaches a toner circulation portion provided outside the effective diameter portion, and the toner falls to the lower portion of the color developing unit 22 due to gravity. Below the color developing unit 22, a screw-like second toner conveying member 28 is disposed in parallel with the developing roller 23, the supply roller 25 and the first toner conveying member 27, and is opposite to the first toner conveying member 27. The toner is rotated so as to convey the toner in the direction, and the toner not used in the developing process is conveyed to the toner storage unit 29. By appropriately setting the toner conveyance amounts of the first toner conveyance member 27 and the second toner conveyance member 28, the toner amount in the color developing unit 22 is not detected and complicated toner supply amount control is performed on the supply roller 25. The small color developing device 6 can supply toner, has a high degree of layout freedom, and has a small cross-sectional occupation ratio with respect to the photosensitive belt 1. Note that the color toner cartridge 30 of FIG. 3 is detachable from the toner accommodating portion 29, and the color toner cartridge 30 is replaced when the toner is replenished.

  The black developing device 7 is a developing device in which black toner is contained in the developing container 41, and is a developing device integrally formed as a so-called developing cartridge in which the life of the developing device is replaced when the toner ends. Similar to the color developing unit 22 of the color developing unit 6, the developing roller 23 faces the photosensitive belt 1 so that the developing roller 23 rotates in the same direction as the moving direction of the photosensitive belt 1 with a predetermined linear velocity ratio. Arranged. Above the developing roller 23, a supply roller 25 made of an elastic material such as polyurethane foam slides on the rubbing portion with the developing roller 23 and rotates in the same direction as the developing roller 23 with a predetermined linear velocity ratio. Further, a developing blade 26 made of a thin plate having a spring property such as stainless steel is provided so that one end thereof is in contact with the developing roller 23. In the developing container 41, a first agitator 42 and a second agitator 43 are provided for conveying and stirring the toner toward the supply roller 25 and the developing roller 23. Although the developing cartridge of the type including the toner is used here, it is a matter of course that a developing device in which the toner cartridge is replaced and replenished like a color developing device may be used. Further, the black developing device 7 can swing in the horizontal direction with respect to the photosensitive belt 1, and is separated from the photosensitive belt 1 when not developing, and approaches or contacts the photosensitive belt 1 when developing.

  As the process cartridge 31, the photosensitive belt 1, the charging charger 4, the intermediate transfer belt 10, the intermediate transfer belt cleaning device 16, the registration roller 50 </ b> B, and the conveyance roller 20 </ b> B are integrated, and the waste toner collection container 15 is a process cartridge. 31 is incorporated in a replaceable manner. The surface of the registration roller 50B in the case exterior portion of the process cartridge 31 also has a function as a conveyance guide.

  Here, the waste toner scraped off from the intermediate transfer belt 10 by the cleaning blade 16A is conveyed to the front side of the cross section by the auger 16B provided in the intermediate transfer belt cleaning device 16, and further the front side surface of the process cartridge 31. The toner is transported to the waste toner collecting container 15 by a transport member (not shown) provided in the container and collected. As a result, the waste toner can be collected without replacing the process cartridge 31, so that the life of the process cartridge can be extended.

  The conveying rollers 20A and 20B, the registration rollers 50A and 50B, the transfer roller 14, and the conveying path of the fixing device 49 to the fixing rollers 49A and 49B are arranged substantially parallel to the inclined belt surface of the intermediate transfer belt 10 and are arranged in the main body of the apparatus. The size is reduced.

  The image forming process by the color image forming apparatus described above is performed as follows. First, formation of a multicolor image is performed according to an image forming system described below. In other words, the image data processing unit calculates the data obtained by the color image data input unit that scans the original image with the image sensor, and the image data is temporarily stored in the image memory. Next, the image memory is taken out at the time of recording and input to a color image forming apparatus shown in FIG. 1 as a recording unit. That is, when a color signal output from an image reading apparatus separate from the printer is input to the laser writing system unit 5, a laser beam generated by a semiconductor laser (not shown) in the laser writing system unit 5. Is rotated and scanned by a polygon mirror 5B rotated by a drive motor 5A, the optical path is bent by a mirror through an fθ lens 5C, and the circumference of the photosensitive belt 1 uniformly charged in advance by a charging charger 4 as a charging means. The top surface is exposed to form an electrostatic latent image.

  Here, the image pattern to be exposed is a single-color image pattern when a desired full-color image is color-separated into yellow, magenta, cyan, and black. The formed three-color electrostatic latent image is developed by rotating the rotary color developing device 6 with the yellow, magenta, and cyan developing units sequentially facing the photosensitive belt 1, and is developed and made monochromatic. A single color image is formed (at this time, the black developing device 7 is retracted to the non-developing position with respect to the photosensitive belt 1), and the black electrostatic latent image is developed by the black developing device 7 to develop the color. Then, it is monochromatic to form a monochromatic image. The single-color image formed on the photosensitive belt 1 is sequentially superimposed and transferred onto the intermediate transfer belt 10 that rotates counterclockwise in the drawing while being in contact with the photosensitive belt 1. The yellow, magenta, cyan, and black images superimposed on the intermediate transfer belt 10 are conveyed from the sheet feeding cassette 17 to the transfer unit via the sheet feeding roller 18, the conveying rollers 19A and 19B, and the registration rollers 50A and 50B. The roller 14 comes into contact with the rotating roller 11 portion of the intermediate transfer belt 10 via the transfer paper, and is transferred. At this time, when the transfer roller 14 comes into contact, the image rear end primary transfer portion on the intermediate transfer belt has passed through as described above. After the transfer is completed, the transfer paper is fixed by the fixing device 49 to complete a full color image.

  Next, the configuration of the apparatus main body will be described with reference to FIGS. The apparatus main body structure is composed of a main body frame 9 which is a stationary housing and a front frame 8 which is a front housing which can open the transfer paper conveyance path, and a paper feed cassette 17 is disposed below the main body frame 9. Each developing device and the process cartridge 31 are replaceably disposed in the central portion, and a fixing device 49 is disposed above the developing device and the process cartridge 31 to form a paper discharge stack portion.

  The front frame 8 is supported so as to be rotatable about a rotation support shaft 9A provided on the main body frame 9 serving as a rotation fulcrum. At the time of image formation output, the front frame 8 is supported on the main body frame 9 as shown in FIG. Is retained. By releasing the holding during the jam processing, it can be released in the clockwise direction, and the open state can be maintained by power such as a tension spring. The front frame 8 holds a registration roller 50 </ b> A, a transfer roller 14, and the like that are part of the conveyance path. As a result, when the front frame 8 is opened, the conveyance path is opened as shown in FIG. 4, and paper jam processing is performed. At this time, only the jam processing can be performed without operating the image forming unit, so there is no problem such as toner dropping.

  The main body frame 9 further includes an intermediate frame 40 that holds the process cartridge 31 in a configuration that will be described later, and is supported so as to be rotatable about a rotation support shaft 9B provided on the main body frame 9 serving as a rotation fulcrum. As shown in FIG. The intermediate frame 40 is held by the main body frame 9 during normal times (except when the process cartridge and each developing device are replaced), and can be opened clockwise in the figure by releasing the holding.

  FIG. 6 shows the attachment / detachment position of the process cartridge 31, and FIG. 7 shows the attachment / detachment state of the process cartridge 31. Rail projections 32 are provided on both side surfaces of the process cartridge 31 so as to be parallel to the attaching / detaching operation direction. Correspondingly, the intermediate frame 40 is similarly provided with rail-like grooves 40A for paralleling the attaching / detaching operation direction. Is provided. For this reason, the process cartridge 31 is held by the intermediate frame 40 during mounting. If the process cartridge 31 is operated in the direction of the arrow with the intermediate frame 40 supported and fixed at the position of FIG. 6, the process cartridge 31 can be easily attached and detached from the intermediate frame 40. In particular, if the handle 33 is provided at the front of the process cartridge 31, the operability is further increased. Further, the groove 40A can be mounted without any problem if the process cartridge 31 insertion side is opened in a trumpet shape.

  Here, the operation direction of the process cartridge 31 is a direction stretched between the two rollers of the intermediate transfer belt 10 and the belt surface of the photoreceptor belt 1 is substantially parallel to the intermediate transfer belt surface. Therefore, the space between development and transfer can be reduced, and the cross section of the apparatus main body can be reduced.

  The intermediate frame 40 can be further opened with respect to the attachment / detachment position of the process cartridge 31 and reaches the same position as the opening position of the front frame as shown in FIG. By supporting and fixing the intermediate frame 40 while the process cartridge is mounted at this position, the developing units 6 and 7 disposed on the back side of the process cartridge are made large without having to retract the process cartridge to the outside of the apparatus main body. Since it is opened, the detachability operability of the developing units 6 and 7 is good.

  Here, as shown in FIG. 7 as an example of a mechanism for supporting and fixing the intermediate frame 40 in two stages, two grooves are provided below the rotation fulcrum of the intermediate frame 40, and the leaf spring 34 is an arrow in the figure. It is incorporated in the main body frame so as to swing in a direction with a constant spring force. The swinging tip 34A of the leaf spring 34 is rotated by the intermediate frame 40 so as to correspond to the grooves 40B and 40C, and latches and supports and fixes the intermediate frame 40 in two stages. At this time, the position of the process cartridge 31 in the attaching / detaching rotation direction is supported and fixed so that the gravity center position G of the process cartridge is substantially on the vertical line of the rotation center position of the intermediate frame 40, and the attaching / detaching movement direction is on the substantially vertical line. By aligning the position of the handle 33, the spring force of the leaf spring 34 for supporting and fixing the process cartridge is very small, a sense of stability is obtained when the intermediate frame 40 is rotated, and the process cartridge is gravitational. It can be operated without falling into an unstable state. Further, if the intermediate frame 40 is used as a stopper member for preventing rotation at a second supporting and fixing position of the intermediate frame 40, the groove 40C of the intermediate frame 40 can be eliminated.

  A manual sheet feeding unit 51 as a second sheet feeding unit will be described with reference to FIGS. When not in use, the manual sheet feeding unit 51 is folded on the front frame 8 so as to be substantially parallel to the conveyance path as shown in FIG. 1, and is stored so as not to jump out in front of the apparatus or in the height direction. The manual sheet feeding unit 51 is set to open in the clockwise direction in the drawing when used (FIG. 9), and the sheet feeding method is configured by a friction pad method. In the figure, reference numeral 52 denotes a transfer paper bottom plate which can be rotated about a rotation shaft 52A and is pressed toward the manual feed roller 53 by a spring 52B. In the figure, reference numeral 54 denotes a side guide that aligns both sides of the transfer paper, and is slidable laterally with respect to the bottom plate 52. The manual feed roller 53 further has a friction pad 55A incorporated in the pad base 55 pressed against the manual feed roller 53 side by a spring 55B. It is configured to be conveyed by the rotation of the roller 53.

  That is, in the present embodiment, the normal paper that is normally used is transported from the paper feed cassette disposed inside the main body of the apparatus, and when the special paper such as thick paper is occasionally passed from the manual paper feed unit 51. They are used properly so that they can be transported.

  Here, the surface of the friction pad 55A is inclined by an appropriate angle with respect to the transfer paper entering direction (angle θ in FIG. 11) for separation performance. That is, the friction pad sheet feeding capable of feeding a large number of sheets is the simplest configuration in the friction separation system, and the range of paper quality that can be separated is wide, but the angle between the transfer sheet entering direction and the pad surface is 20 to 40 degrees. It is desirable to set it at 20 to 35 degrees. Further, depending on the conveyance direction of the roller next to the manual feed roller 53, the separation performance of the friction pad 55A is affected. In FIG. 11, when the transfer paper P is conveyed in the direction indicated by the arrow H in FIG. 11, the transfer paper P pushes down the friction pad 55A, and the separation pressure is lowered to cause double feeding. The transport direction of the next roller must be aligned with (upward several degrees). Therefore, as shown in FIG. 12, the direction in which the transfer paper P enters and the direction of the conveyance path from the pad separation to the registration roller 50 are set to form an angle of about 20 to 40 degrees, and from the manual feed roller 53 to the registration roller. 50, the transfer roller 14, and the fixing device 49 are arranged so that the direction of the conveyance path is substantially in a straight line. Note that when the transfer roller 14 and the rollers 49A and 49B of the fixing device 49 are also compatible with transfer paper with a low stiffness, the entry position is slightly shifted downward, so the positions of the fixing rollers 49A and 49B are slightly more than on the straight line. Sometimes it goes down.

  The embodiment described above is of the intermediate transfer belt type, but it is also possible to superimpose four colors on the photosensitive belt 1 ′ as in the second embodiment of the present invention shown in FIG. The same shape and configuration can be taken with respect to the transport unit. In this case, the charging charger 4 is disposed below the waste toner collecting container 15, the laser writing system unit 5 is disposed below the charging toner container 15, and the color and black developing units 6 and 7 are disposed below the charging unit 4. Arrange. This is a difference only due to the difference between using an intermediate transfer belt or a photosensitive belt as a toner image carrier. As shown in the figure, the photoconductor belt system can be further reduced in size, but in this system, a process is performed in which a latent image is formed by developing a latent image by charging and exposing the photoconductor again from a previously transferred toner image. Is carried out a plurality of times, it is difficult to maintain good charging uniformity, and the image quality is inferior to that of the intermediate transfer belt system.

It is sectional drawing which shows one Embodiment of the color image forming apparatus of this invention. FIG. 2 is a cross-sectional view showing an internal configuration of a color and black developing device of the color image forming apparatus of FIG. 1. FIG. 2 is a perspective view of a color developer of the color image forming apparatus in FIG. 1. FIG. 2 is a cross-sectional view of the color image forming apparatus of FIG. 1 with a front frame opened. It is a perspective view of a process cartridge and an intermediate frame for supporting the process cartridge. It is sectional drawing which shows the attachment or detachment position of a process cartridge. It is a side view which shows the attachment or detachment state of a process cartridge. It is sectional drawing of the open state of an intermediate | middle frame. FIG. 3 is a cross-sectional view illustrating a state in which a manual sheet feeding unit as a second sheet feeding unit of the color image forming apparatus of FIG. 1 is opened and used. FIG. 10 is a cross-sectional view of a main part showing a transfer paper conveyance state in the state of FIG. 9. FIG. 10 is a cross-sectional view for explaining a transfer sheet conveyance direction and separation performance in the state of FIG. 9. FIG. 10 is a conceptual diagram illustrating a transfer paper conveyance state in the state of FIG. 9. It is sectional drawing which shows other embodiment of the color image forming apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor belt 2, 3 Rotating roller 4 Charging charger 5 Laser-writing system unit 6 Color developing device 7 Black developing device 8 Front frame 9 Main body frame 10 Intermediate transfer belt 11, 12 Rotating roller 13 Bias brush 14 Transfer roller 15 Waste toner collection container 16 Intermediate transfer belt cleaning device 17 Paper feed cassette 18 Paper feed rollers 19A, 19B, 20A, 20B Transport roller 21 Casing 22 Color development unit 23 Development roller 24 Partition plate 25 Supply roller 26 Development blade 27 First toner Conveying member 28 Second toner conveying member 29 Toner container 30 Color toner cartridge 31 Process cartridge 32 Rail protrusion 33 Handle 34 Leaf spring 35 Backup roller 40 Intermediate frame 41 Developer container 42 First agitator 43 Second agitator Motor 49 the fixing device 49A, 49B fixing roller 50A, 50B registration rollers 51 hand bypass unit 52 bottom plate 53 Bypass roller 54 side guides 55 pad stand 55A friction pad

Claims (8)

The device body;
An intermediate transfer belt stretched by at least two rollers and rotatable with respect to the apparatus main body;
An image forming apparatus comprising: a cover rotatable with respect to the apparatus main body;
The intermediate transfer belt is configured to be rotatable by rotating the cover, and is configured to be detachable from a frame supported by the apparatus main body,
The cover is configured to hold the intermediate transfer belt, and is configured to be rotatable to a position where a surface of the intermediate transfer belt facing the cover faces downward, and is open to the apparatus main body by a spring. An image forming apparatus configured to be capable of maintaining the image quality.   The image forming apparatus according to claim 1, wherein the intermediate transfer belt is inclined with respect to a horizontal direction in a state where the cover holds the intermediate transfer belt from below.   The image forming apparatus according to claim 1, wherein the image forming apparatus includes a plurality of units that are detachable from the apparatus main body and each include a toner storage portion and a developing roller. A process cartridge including the intermediate transfer belt and rotatably supported between an operating position and a retracted position;
The cover is rotatably supported in a closed position and an open position with respect to the apparatus main body,
4. The image forming apparatus according to claim 3, wherein openings for attaching and detaching the plurality of units are formed by rotating the cover and the process cartridge from the closed position and the operating position, respectively. apparatus. A paper feed cassette on the lower side of the apparatus body,
The image forming apparatus according to claim 1, wherein a rotation fulcrum of the cover is provided on a sheet feeding port side of the sheet feeding cassette. It has a manual paper feed unit that is connected to the transfer paper transport path and transports it,
The manual sheet feeding unit takes two positions, a used position for feeding paper and an unused position stored in the apparatus body,
6. The image forming apparatus according to claim 1, wherein the manual sheet feeding unit is housed substantially in parallel with the intermediate transfer belt when in the unused position.   The manual paper feed unit is provided so that an angle between a paper entering direction of the manual paper feed unit and a direction of the transfer paper conveyance path forms an acute angle when in the use position. 6. The image forming apparatus according to 6.   The image forming apparatus according to claim 6, wherein the manual sheet feeding unit is embedded in the cover when the manual sheet feeding unit is in the unused position.

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