JP2007133248A - Image forming unit and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming unit capable of yielding an output image of higher image quality by accurately positioning a developing means kept in a developing state with respect to an image carrier, and also performing stable developing operation by surely transmitting driving force from a driving means to the developing means. <P>SOLUTION: In the image forming unit, a developing unit 150 rotatably supporting two developing rolls 111 and 121 is supported by supporting means 155 and 156 so that it can move to approach to or separate from a photoreceptor drum 101 and turn centering around an axis parallel with the shaft of the photoreceptor drum, and is energized to one side in a movable direction by an energizing means 157, then the roller members 116 and 126 at both ends of the two developing rolls are made to abut on the cam surface 104a of a cam member 104 at any time, whereby a developing gap is accurately stably regulated without requiring the higher accuracy and the higher strength of parts, and the image forming unit is made more inexpensive and the image quality of the output image is made higher. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile, a printer, or a plotter, and more specifically, includes an image forming unit having a plurality of developing units that store different color developers, and the image forming unit. The present invention relates to an image forming apparatus.

  As an image forming apparatus for transferring and outputting a multi-color image formed on an intermediate transfer member to a recording material, a plurality of image forming units each including a latent image forming unit and a plurality of developing units are provided around the image carrier, Patent Document 1 (Japanese Patent Laid-Open No. 10-177286) and Patent Document 2 (Patent Document 2) obtain a multi-color image by sequentially transferring a visible image formed by an image forming unit onto a single intermediate transfer member. JP 2003-167410 A) and Patent Document 3 (JP 2003-307903 A).

  In the case of forming a full-color image of four colors, in a method using a single image carrier and intermediate transfer member, it is necessary to dispose four developing means around the image carrier, and the intermediate transfer member 4 In contrast to the need to rotate, this type of image forming apparatus has two developing means arranged around the image carrier, so that full-color image formation is possible with two rotations of the intermediate transfer member. It is possible to reduce the size / diameter of the image carrier and speed up the apparatus. The basic operation of this method is described in detail in paragraphs [0016] to [0031] of Patent Document 1.

  Further, in Patent Document 2 and Patent Document 3, two developing rollers are disposed in the developing unit so as to be rotatable about an axis parallel to the rotating shaft of the photosensitive drum, and the developing unit is rotated on the rotating shaft of the photosensitive drum. The image forming unit is supported so as to be rotatable about a rotation axis substantially parallel to the image forming unit, the developing unit is rotated by a predetermined rotation angle with respect to the image forming unit, and one of the two developing rollers is rotated. There has been proposed an image forming apparatus having a developing function switching means for switching a distance between a developing roller and a photosensitive drum to a developing state position.

In these prior arts, the developing unit can be rotated to switch the distance between the photosensitive drum and the developing roller (development gap) and simultaneously switch the driving force transmission state between the driving gear and the developing roller gear. It is said that reliable development function switching can be realized at low cost.
Patent Document 4 (Japanese Patent Laid-Open No. 2004-279934) and Patent Document 5 (Japanese Patent Laid-Open No. 2004-309877) also show other configurations for switching the driving force transmission state.

  Further, Patent Document 6 (Japanese Patent Application Laid-Open No. 2004-37872) discloses that when a black and white image is output, the two developing rollers of the image forming unit on the side that does not include the black (Bk) developing roller are deactivated. The configuration is presented. In this application, it is possible to prevent the wear and deterioration of the photoconductor film due to unnecessary developer contact, and the wear and deterioration of the developer due to unnecessary stirring, and to reduce the running cost by extending the life of the photoconductor and developer. In addition, an image forming apparatus capable of reducing the environmental load can be realized.

Japanese Patent Laid-Open No. 10-177286 JP 2003-167410 A JP 2003-307903 A JP 2004-279934 A JP 2004-309877 A JP 2004-37872 A JP 2003-208011 A

  As described above, the two developing rollers are disposed in the developing unit so as to be rotatable about an axis parallel to the rotation axis of the photosensitive drum, and the developing unit is a rotation shaft substantially parallel to the rotation axis of the photosensitive drum. The image forming unit is rotatably supported around the image forming unit, the developing unit is rotated by a predetermined rotation angle with respect to the image forming unit, and one of the two developing rollers, the photosensitive drum, The image forming apparatus having the developing function switching means for switching the interval to the development state position has the following problems.

  The parallelisms of the rotation center axis of the two developing rollers and the photosensitive drum and the rotation center axis of the image forming unit are determined by component accuracy, and in particular, there are many components between the two developing rollers and the photosensitive drum. Therefore, it is difficult to ensure parallelism with parts accuracy, and the development gap cannot be defined with high accuracy. In the prior art described in Patent Document 3, Patent Document 4, and Patent Document 5 described above, as an example, a roller member in which an eccentric cam provided coaxially with the rotating shaft of the photosensitive drum is provided coaxially with the developing roller. Although a configuration is shown in which the development unit is rotated by rotating while being in contact with the image forming unit to achieve high accuracy in the development gap, it is supported by a rotation shaft fixedly arranged on the image forming unit. All of the roller members at both ends of the two developing rollers rotatably supported by the developed developing unit are cams at both ends on the photosensitive drum shaft supported by a rotating shaft fixedly arranged separately from the image forming unit. It is difficult to always make contact with a member even if all the parts interposed between them are formed with high precision, and it is necessary to provide a gap in consideration of part variation between the roller member and the eccentric cam. Arise, this Gap there is a problem that causes variation of the development gap.

  For this reason, in Patent Document 3, a cam member is provided with an adjustment mechanism, and the rotation angle in the development switching operation can be arbitrarily adjusted by the both side plates of the image forming unit, whereby the parallelism between the developing roller and the photosensitive drum is shifted. However, the addition of an adjustment mechanism increases the size and cost of the device, and there is a limit to the adjustment accuracy of the cam member, making it difficult to completely eliminate the parallelism deviation. It is. Further, when the driving force from the drive transmission gear acts on the developing roller and the rigidity of the housing of the developing unit that supports the developing roller is insufficient, the parallelism between the photosensitive drum and the developing roller is shifted due to the driving force, and the developing gap is increased. It will fluctuate. In addition, it is difficult to prevent this by increasing the rigidity of the housing of the developing unit, and greatly increasing the rigidity of the housing of the developing unit is a major obstacle to cost reduction.

  Further, Patent Document 6 shows a configuration in which both of the two developing rollers in the image forming unit can be brought into a non-operating state. However, the rotation of the developing unit in which both the developing rollers are in a non-developing state is shown. By providing a moving position, when one developing roller is in the developing state, the other developing roller is more distant from the photoreceptor than necessary, so the apparatus becomes larger and the developing state switching time is prolonged. Inevitable.

  As a configuration for solving the above problems, a configuration described in Patent Document 7 (Japanese Patent Laid-Open No. 2003-208011) is conceivable. In this prior art, the developing units disposed around the photosensitive drum and urged toward the photosensitive drum are rotatably provided on both sides of the photosensitive drum independently of the photosensitive drum, and at least one of the outer peripheral surfaces is provided on the outer peripheral surface. The shaft of the developing roller is supported so as to be in contact with the cam surface of the cam member in which two or more grooves are formed. For this reason, since the parallelism between the photosensitive drum and the developing roller is substantially defined by the accuracy of the cam member parts, it is possible to maintain a high accuracy of the developing gap and to apply an impact when the developing roller contacts the photosensitive drum. It is said that it can be minimized.

  However, it is necessary to provide means for supporting each developing unit so as to be movable with respect to the photosensitive drum and means for urging the developing unit toward the photosensitive drum, and each developing unit is independently brought close to / separated from the photosensitive drum. A complicated mechanism and a large space are required to support the slidable support in the direction of movement and to bias the sway in the direction of movement, resulting in an increase in the size of the apparatus and an increase in cost.

  In addition, when the developing roller on the photosensitive drum or the contact / non-contact state of the developer on the developing roller is switched, the load on the photosensitive drum rotating at a constant speed fluctuates, and when the developing color is switched, the photosensitive drum The problem that the rotational speed fluctuates is inevitable. If the development color is changed during exposure to the photosensitive drum or the intermediate transfer operation from the photosensitive drum to the intermediate transfer belt, the image is disturbed. It is necessary to carry out at the timing when the above process is not in operation, and there is an area on the intermediate transfer belt where an image cannot be formed within the range of the distance between the exposure position and the intermediate transfer position + the distance the image advances during the development color switching operation This leads to an increase in the size of the intermediate transfer belt. This not only causes an increase in the size and cost of the apparatus, but also causes a problem that it is difficult to improve the image quality of the output image due to the influence of elongation, vibration, and the like due to a decrease in rigidity of the intermediate transfer belt.

  The developing unit is urged toward the photosensitive drum, and the shaft of the developing roller contacts the cam member, so that the parallelism between the photosensitive drum and the developing roller and the developing gap are defined, but the developing roller is driven to rotate. Therefore, the shaft of the developing roller needs to be brought into contact with the cam member with a sufficient urging force so that the parallelism between the developing roller and the photosensitive drum is not shifted by the driving force. For this reason, it is necessary to ensure high rigidity in the housing of the developing unit so that deformation does not occur even when a sufficient urging force is applied, leading to an increase in component costs. In addition, the rotation of the cam member for switching the development color must generate a force that is against the sufficient urging force, so that there is a problem that a large amount of power is required or that high-speed switching is difficult. .

The present invention has been made in view of the above circumstances, and by positioning the developing means in the developing state with respect to the image carrier with high accuracy without incurring the complexity, size and cost of the apparatus. An image forming unit capable of improving the image quality of an output image and reliably transmitting a driving force from the driving unit to the developing unit and performing a stable developing operation, and an image forming apparatus including the image forming unit It aims to be realized.
Further, in an image forming unit having a development switching mechanism for switching the development color by switching between contact / non-contact of the developer carrier and the toner layer with respect to the image carrier, the influence on the image by the development color switching operation is prevented, In the image forming apparatus equipped with this image forming unit, it is possible to reduce the size and cost of the apparatus by reducing the size of the intermediate transfer member, and to improve the output image quality by increasing the rigidity of the intermediate transfer member. It aims at realizing.

In order to achieve the above object, the present invention employs the following technical means.
The first means of the present invention includes developing means for visualizing a latent image of the same rotating image carrier in an arbitrary color and another developing for visualizing in a color different from the arbitrary color. And an image forming unit having a configuration in which the respective units are arranged so as to face each other and be adjacent to the outer periphery of the image carrier, and when the colors are switched, the two developing units are rotated during the rotation of the image carrier. In an image forming unit for switching the developing function from one of the developing means to the other developing means, the one developing means and the other developing means are centered on an axis parallel to the rotation axis of the image carrier. A holding means for rotatably holding; a roller member rotatably supported at both ends on the rotation shaft of the two developing means; and a rotation parallel to the rotation shaft at both ends in the rotation axis direction of the image carrier. Provide a cam member with a moving shaft, The cam member rotates while being in contact with the roller member supported by the two developing means, so that the distance between the one developing means and the image carrier is in the developing state, and the other developing means and the The position where the distance between the image carrier is in a non-development state, or the distance between the other development means and the image carrier is in the development state, and the distance between the one development means and the image carrier is in a non-development state. A cam surface for changing a distance between each developing means and the image carrier at any position, and the holding means is centered on a rotation axis parallel to the rotation axis of the image carrier relative to the image carrier. Support means for supporting the image bearing member so as to be able to move and moving in one direction close to and away from the image carrier, and biasing means for biasing the holding means in one direction of movement relative to the image carrier. Means for applying the biasing means. The roller member that is supported by the two developing means is characterized in that is brought into contact at all times with the cam surface by the force (claim 1).

  The second means of the present invention is a developing means for visualizing a latent image of the same rotating image carrier in an arbitrary color and another development for visualizing in a color different from the arbitrary color. And an image forming unit having a configuration in which the respective units are arranged so as to face each other and be adjacent to the outer periphery of the image carrier, and when the colors are switched, the two developing units are rotated during the rotation of the image carrier. In an image forming unit for switching the developing function from one of the developing means to the other developing means, the one developing means and the other developing means are centered on an axis parallel to the rotation axis of the image carrier. A holding means for rotatably holding; a roller member rotatably supported at both ends on the rotation shaft of the two developing means; and a rotation parallel to the rotation shaft at both ends in the rotation axis direction of the image carrier. Provide a cam member with a moving shaft, The cam member rotates while being in contact with the roller member supported by the two developing means, so that the distance between the one developing means and the image carrier is in the developing state, and the other developing means and the The position where the distance between the image carrier is in a non-development state, or the distance between the other development means and the image carrier is in the development state, and the distance between the one development means and the image carrier is in a non-development state. A cam surface for changing a distance between each developing means and the image carrier at any position, and the holding means is centered on a rotation axis parallel to the rotation axis of the image carrier relative to the image carrier. Support means for supporting the image bearing member so as to be able to move and moving in one direction close to and away from the image carrier, and biasing means for biasing the holding means in one direction of movement relative to the image carrier. Means for applying the biasing means. The roller member supported by the two developing means is always brought into contact with the cam surface by force, and is rotated coaxially with the driving means for rotating the developing means and the rotation shaft for supporting the holding means. An arbitrary driving force transmitting means is provided, and a driving force from a developing means driving source provided in the image forming apparatus main body is provided to the developing means via a driving force transmitting means on a rotation shaft of the holding means. The driving means and the developing means are transmitted (claim 2).

  According to a third means of the present invention, in the image forming unit of the first means, the cam members provided at both ends in the rotation axis direction of the image carrier are rotated by the cam member. The distance between the first developing means and the image carrier is not developed, and the distance between the other developing means and the image carrier is not developed, and the distance between the one developing means and the image carrier is not developed. The distance between the one developing means and the image carrier is in a non-developing state and the other developing means is between the position where the distance between the other developing means and the image carrier is in the developing state. And the image carrier has a position where the image carrier is in a non-development state (claim 3).

  According to a fourth means of the present invention, in the image forming unit of the first means, the cam members provided at both ends in the rotational axis direction of the image carrier are rotated by the cam member. The distance between the first developing means and the image carrier is not developed, and the distance between the other developing means and the image carrier is not developed, and the distance between the one developing means and the image carrier is not developed. The distance between the one developing means and the image carrier is in the developing state, and the other developing means is between the position where the distance between the other developing means and the image carrier is in the developing state. And the image carrier has a position where the development state is established (claim 4).

  According to a fifth means of the present invention, in the image forming unit of the fourth means, the cam members provided at both ends in the rotation axis direction of the image carrier are rotated by the cam member. At the same time as the distance between the image carrier and the image carrier is in the developed state and the distance between the other developer means and the image carrier is moved from the non-developed position to the developed position. A cam surface is formed so that the distance between the developing means and the image carrier starts to move from a position in the developing state to a position in the non-developing state (Claim 5).

  According to a sixth means of the present invention, in the image forming unit of the first means, the cam member is provided so as to be coaxially rotatable with respect to a rotation axis of the image carrier. .

  According to a seventh means of the present invention, in the image forming unit of the first means, a driven member is fixed on the same axis of the rotation shaft with respect to the one developing means and the other developing means, and the cam member rotates. When the distance between the developing means and the image carrier is in the development state due to the movement, the driving force is transmitted to the driven member of the developing means, and the distance between the developing means and the image carrier is not developed. A driving force transmitting means that is in a non-transmitting state with the driven member of the developing means is provided, and when the driven member of the developing means is driven in the driving force transmitting state, the driven member is The driving force transmitting means is provided at a position where the acting driving force has a force in a direction in which the roller member comes into contact with the cam surface (Claim 7).

  According to an eighth means of the present invention, in the image forming unit of the first means, a driving means for rotationally driving the one developing means and the other developing means is provided, and a rotating shaft of each developing means and the driving means are provided. Are connected coaxially to each of the rotation shafts of the first and second rotation shafts, and transmit the rotational driving force of the driving means to the developing means, and the one developing means and the other developing means rotate the cam member with respect to the driving means. Accordingly, a driving force transmitting means is provided that allows the developing means to move between a position where the distance between the image carrier and the image carrier is in a developed state and a position where the distance between the image carrier is in a non-developed state. (Claim 8).

  According to a ninth means of the present invention, in the image forming unit of the first means, there is provided a driving means for rotationally driving the one developing means and the other developing means, the rotating shaft of each developing means and the driving means. Driving force transmitting means connected coaxially to each of the rotating shafts of the driving means for transmitting the rotational driving force of the driving means to the developing means. The driving force transmitting means includes the rotating shaft of the developing means and the driving means. The driving force transmission state is released when the rotating shaft moves by a specified distance in the rotating shaft direction, and the rotating shaft of the developing unit is brought into the developing state by the rotation of the cam member with respect to the rotating shaft of the driving unit. A driving force transmitting portion that is movable between the position and the non-development state, and at least one of the cam members provided at both ends in the rotation axis direction of the image carrier is rotated. According to the above The developing unit and the image carrier are in a developing state, the other developing unit and the image carrier are in a non-developing state, the rotating shaft of the one developing unit and the rotating shaft of the driving unit A position where the driving force transmitting means connected to the driving force is in a driving force transmitting state and the driving force transmitting means connected to the rotating shaft of the other developing means and the rotating shaft of the driving means is in a driving force transmission canceling state. , And the distance between the other developing means and the image carrier is in a developed state, and the distance between the one developing means and the image carrier is in a non-developed state, and the rotation shaft of the other developing means and the drive The driving force transmitting means connected to the rotating shaft of the means is in a driving force transmitting state, and the driving force transmitting means connected to the rotating shaft of the one developing means and the rotating shaft of the driving means is driven. In the release state position, the cam surface to change the rotation axis direction between the rotation axis of the rotary shaft and the driving means of each of the developing means is characterized by being formed integrally (claim 9).

  According to a tenth means of the present invention, in the image forming unit of the second means, the holding means transmits the driving force transmitted from the developing means driving source to the driving force transmitting means on the rotation shaft of the holding means. The component in the direction supported so as to be movable is a direction in which the holding means is brought close to the image carrier (claim 10).

  According to an eleventh means of the present invention, in the image forming unit of the second means, the developing means driving source is a rotational driving means capable of forward and reverse rotation, and between the developing means driving source and the two developing means. Each driving force transmission system is provided with a one-way clutch, and when the developing device driving source is rotated forward, the one-way clutch provided in the driving force transmission system to one developing device is locked and driven to the one developing device. While the force is transmitted, the one-way clutch provided in the driving force transmission system of the other developing means is idled, and the driving force is not transmitted to the other developing means (claim 11).

  In the twelfth means of the present invention, in the image forming unit of the eleventh means, when the developing means driving source is rotated forward, the one-way clutch provided in the driving force transmission system to one developing means is locked, The driving force is transmitted to the one developing means and the developer agitating / conveying means, and the one-way clutch provided in the driving force transmission system of the other developing means is idled, and the other developing means and the developer agitating / conveying means A driving force is not transmitted to the head (claim 12).

  According to a thirteenth aspect of the present invention, in the image forming unit of the second means, the cam members provided at both ends in the rotation axis direction of the image carrier are rotated by the cam member. A position where the distance between the first developing means and the image carrier is in a developed state, and a distance between the other developing means and the image carrier is in a non-developed state, and a distance between the one developing means and the image carrier is not developed. The distance between the one developing means and the image carrier is in a non-developing state and the other developing means is between the position where the distance between the other developing means and the image carrier is in the developing state. Driving force transmitting means for transmitting the driving force from the developing means driving source to the driving force transmitting means on the rotating shaft of the holding means, On the rotating shaft of the holding means Is characterized in that it is provided with a movement from the driving force transmitting state of the power transmission means in a direction for spacing said retaining means to said image bearing member at an acceptable position (claim 13).

  According to a fourteenth aspect of the present invention, in the image forming unit of the second means, the cam members provided at both ends in the rotation axis direction of the image carrier are rotated by the cam member. A position where the distance between the first developing means and the image carrier is in a developed state, and a distance between the other developing means and the image carrier is in a non-developed state, and a distance between the one developing means and the image carrier is not developed. The distance between the one developing means and the image carrier is in the developing state and the other developing means is between the position where the distance between the other developing means and the image carrier is in the developing state. The driving force transmitting means for transmitting the driving force from the developing means driving source to the driving force transmitting means on the rotating shaft of the holding means has a position where the interval between the image carriers is in the developing state. Driving on the pivot axis of the means Is characterized in that it is provided with a movement from the driving force transmission state of the transmission means in a direction to close the holding means to the image bearing member at an acceptable position (claim 14).

According to a fifteenth aspect of the present invention, there is provided developing means for visualizing a latent image of the same rotating image carrier in an arbitrary color and another development for visualizing in a color different from the arbitrary color. And an image forming unit having a configuration in which each means is arranged so as to face and adjoin the outer periphery of the image carrier, and when the color is switched in the image forming unit, the 2 The developing function is switched from any one of the two developing means to the other developing means, and the visible image on the image carrier obtained by making the visible image is sequentially transferred to the intermediate transfer body, In the image forming apparatus for obtaining a recording image by further transferring the transfer image on the intermediate transfer member to a recording material, the image forming unit of any one of the first to fourteenth means is provided as the image forming unit. (Claim 15)
According to a sixteenth aspect of the present invention, in the image forming apparatus according to the fifteenth aspect, a plurality of the image forming units are arranged in parallel along the intermediate transfer member.

  In the image forming unit of the first means, a holding means (for example, a developing unit) that rotatably supports two developing means (for example, developing rollers) is brought close to the image carrier (for example, a photosensitive drum) by the supporting means. It is movable in the separating direction and is supported so as to be rotatable about an axis parallel to the photosensitive drum axis, and is biased in one of the movable directions by the biasing means, and the roller members at both ends of the two developing rollers are cam members. By constantly abutting on the cam surface, it is possible to stably define the development gap with high accuracy without incurring high precision and high strength of the parts, reducing the cost of the image forming unit, and high image quality of the output image. Can be realized.

  In the image forming unit of the second means, the holding means (for example, the developing unit) that rotatably supports the two developing means (for example, the developing roller) is brought close to the image carrier (for example, the photosensitive drum) by the supporting means. It is movable in the separating direction and is supported so as to be rotatable about an axis parallel to the photosensitive drum axis, and is biased in one of the movable directions by the biasing means, and the roller members at both ends of the two developing rollers are cam members. By constantly abutting on the cam surface, it is possible to stably define the development gap with high accuracy without incurring high precision and high strength of the parts, reducing the cost of the image forming unit, and high image quality of the output image. Can be realized. In addition, a driving force transmission means (for example, a driving force transmission gear) for transmitting a driving force from the main body driving source to the upper and lower developing rollers is provided on the developing unit rotation shaft so as to be rotatable, thereby acting on the developing unit. The development unit rotation direction component of the driving force can be eliminated, the development unit can be prevented from being twisted, and the development unit can be kept in constant contact with the cam even if the urging force is reduced. Maintenance is possible. In addition, since both ends of the photosensitive drum are always in contact with the cam, there is no load fluctuation or impact on the photosensitive drum at the time of development switching, and the rotational speed fluctuation of the photosensitive drum or the photosensitive drum Vibration can be prevented.

  In the image forming unit of the third means, in addition to the structure of the first means, the integral developing unit can move in the approaching / separating direction with respect to the photosensitive drum. -Even in the above case where it is necessary to provide a developing unit rotating position where the magenta developing roller is in a non-developing state, the retracting interval of the developing roller can be minimized, and the image forming unit can be downsized and the development switching operation can be performed. Can be speeded up.

  In the image forming unit of the fourth means, in addition to the structure of the first means, the integral developing unit is configured to move in the approaching / separating direction with respect to the photosensitive drum. By forming the cam member so that the timing at which the photosensitive member load fluctuation accompanying the completion of the switching to the developing state and the photosensitive member load fluctuation accompanying the start of switching from the developing state to the non-developing state are close to each other, When an image is formed (transferred) from the drum onto an intermediate transfer member (for example, an intermediate transfer belt) of the image forming apparatus main body, an area where an image cannot be formed on the intermediate transfer member (for example, an intermediate transfer belt) can be reduced. By reducing the size of the belt, it is possible to reduce the size and cost of the image forming apparatus. By increasing the rigidity of the intermediate transfer belt, it is possible to prevent stretching, vibration, etc., and to achieve higher output image quality. It is possible.

  In the image forming unit of the fifth means, in addition to the configuration of the fourth means, the switching of the developing roller to be developed from the non-development state to the development state is completed, and at the same time, the development state of the developing roller being developed is changed from the development state to the non-development state. By starting the switching to the developing state, the photosensitive member load fluctuation accompanying the completion of the switching from the non-developing state to the developing state and the photosensitive member load fluctuation accompanying the start of switching from the developing state to the non-developing state are performed at the same timing. By forming the cam member so as to be generated, the area in which an image cannot be formed on the intermediate transfer belt is minimized, and the size of the image forming apparatus can be greatly reduced and the cost can be significantly reduced by greatly reducing the size of the intermediate transfer belt. At the same time, the intermediate transfer belt can be further rigidly prevented from stretching, vibrating, etc., and the output image can be greatly improved in image quality.

  In the image forming unit of the sixth means, in addition to the configuration of the first means, a cam member is provided on the same axis as the photosensitive drum, thereby reducing the number of parts defining the developing gap between the photosensitive member and the developing roller. It is possible to increase the accuracy of the development gap, and it is possible to realize space saving by simplifying the configuration and cost reduction by reducing the number of parts.

  In the image forming unit of the seventh means, in addition to the configuration of the first means, the development function switching and the development drive switching are realized by the same configuration and operation, so that the image forming unit can be reduced in size and cost. In addition, the development gap and development roller gear transmission state can be defined with high precision and stability, and fluctuations in the rotational load and impact / vibration of the photosensitive drum during development switching can be prevented. It is possible to improve the image quality and improve the reliability of the apparatus.

  In the image forming unit of the eighth means, in addition to the configuration of the first means, it is possible to stably define the development gap with high accuracy, and to prevent fluctuations in the rotational load of the photosensitive drum and shock / vibration at the time of development switching. Therefore, it is possible to improve the image quality of the output image and improve the reliability of the apparatus.

  In the image forming unit of the ninth means, in addition to the configuration of the first means, it is possible to stably define the development gap with high accuracy and to prevent fluctuations in the rotational load of the photosensitive drum and shock / vibration at the time of development switching. Therefore, it is possible to improve the image quality of the output image and improve the reliability of the apparatus.

  In the image forming unit of the tenth means, in addition to the structure of the second means, the developing unit can be constantly brought into contact with the cam member more stably even if the urging force is reduced, and the development gap can be highly accurate. Can be maintained.

  In the image forming unit of the eleventh means, development drive switching can be realized with a simple configuration without adding a mechanism requiring electric power in addition to the configuration of the second means. And low power consumption can be realized.

  In the image forming unit of the twelfth means, in addition to the constitution of the eleventh means, it is possible to realize a long life of the developer by reducing unnecessary stirring and conveying operations, so that the reliability of the apparatus and the output cost can be reduced. It becomes.

  In the image forming unit of the thirteenth means, in addition to the structure of the second means, the integral developing unit can move in the approaching / separating direction with respect to the photosensitive drum. -Even in the above case where it is necessary to provide a developing unit rotating position where the magenta developing roller is in a non-developing state, the retracting interval of the developing roller can be minimized, and the image forming unit can be downsized and the development switching operation can be performed. Can be speeded up.

  In the image forming unit of the fourteenth means, in addition to the structure of the second means, the integrated developing unit is movable in the approaching / separating direction with respect to the photosensitive drum. By forming the cam member so that the timing at which the photosensitive member load fluctuation accompanying the completion of the switching to the developing state and the photosensitive member load fluctuation accompanying the start of the switching from the developing state to the non-developing state occur is formed, When an image is formed (transferred) on an intermediate transfer member (for example, an intermediate transfer belt) of the image forming apparatus main body, an area where an image cannot be formed on the intermediate transfer member (for example, an intermediate transfer belt) can be reduced. The size of the image forming apparatus can be reduced and the cost can be reduced by reducing the size of the intermediate transfer belt, and the rigidity of the intermediate transfer belt can be increased to prevent stretching, vibration, etc. It is possible.

In the image forming apparatus of the fifteenth means,
By providing the image forming unit according to any one of claims 1 to 14, the image forming apparatus can be reduced in size and cost. Further, by increasing the rigidity of the intermediate transfer member (for example, an intermediate transfer belt), elongation, vibration, and the like can be prevented, and a higher image quality of the output image can be realized.
In the image forming apparatus of the sixteenth means, a small and low-cost color image forming apparatus can be realized by arranging a plurality of image forming units along the intermediate transfer belt.

Hereinafter, the configuration, operation and action of the present invention will be described in detail with reference to the drawings.
First, the configuration of the image forming apparatus according to the fifteenth and sixteenth means of the present invention will be described. FIG. 1 shows a configuration example of an image forming apparatus to which the present invention is applied. In FIG. 1, two image forming units each having a configuration in which two developing means (for example, a developing device having a developing roller) are arranged in parallel to one image carrier (hereinafter referred to as a photosensitive drum) are used. Schematic configuration diagram showing a main part of an image forming apparatus in which forming units I and II are arranged side by side along an intermediate transfer member (endless intermediate transfer belt in the example shown in the figure) 105 to form a full-color image on the intermediate transfer belt 105. It is. Such a configuration is characterized in that the size of the apparatus can be reduced and the printing speed can be increased as compared with a configuration using one image forming unit (refer to Patent Document 3 described above for details).

  In this image forming apparatus, at the time of image formation, the two photosensitive drums 101 and 201 are rotationally driven in the direction of an arrow (clockwise direction) in the drawing, and the surface thereof is contacted by a charger (for example, a charging roller or a charging brush). Or a contact charger such as a charging charger) 102, 202, and then using an exposure device (for example, a laser scanning optical writing device or a light emitting diode (LED) array). (Optical writing device) 103, 203 performs exposure according to input image information to form an electrostatic latent image. The cyan developing device (C color unit) 110, the magenta developing device (M color unit) 120, the yellow developing device (Y color unit) 210, and the black developing device (Bk color unit) 220 are connected to the development switching mechanisms 114, 124, 214. 224, the developing roller 111 for the first color (cyan (C)) is moved to the developing position facing the photosensitive drum 101, and the developing roller 211 for the second color (yellow (Y)) is moved to the photosensitive drum 201. The toner is attached to the electrostatic latent image on the photosensitive drum 101 to be developed as a cyan toner image, and the toner is attached to the electrostatic latent image on the photosensitive drum 201. To develop a yellow toner image. The cyan toner image and the yellow toner image are contacted with the photosensitive drums 101 and 201 on the intermediate transfer member (intermediate transfer belt) 105 that rotates in the direction of the arrow in the drawing at the primary transfer portions T11 and T12. Primary transfer is performed. Then, the primary transfer process is sequentially performed for the other two colors, that is, magenta (M) and black (Bk), and the four color toner images are superimposed on the intermediate transfer belt 105. These four color toner images are transferred to a recording material P conveyed by a sheet feeding / conveying means (not shown) from a sheet feeding cassette (not shown) in a secondary transfer member T2 (for example, a secondary transfer roller). A full-color image can be obtained by performing the secondary transfer in a lump by 106. On the other hand, the remaining toner on the surface of each of the photosensitive drums 101 and 201 after the primary transfer is removed by a cleaning device (not shown), and the intermediate transfer belt 105 after the secondary transfer is similarly left on the surface by a cleaning device (not shown). Toner is removed.

  The configuration example of the image forming apparatus according to the present invention has been described above. Next, a specific embodiment of the image forming unit provided in the image forming apparatus shown in FIG. 1 will be described.

  First, an embodiment of the image forming unit according to the first means and the third to ninth means of the present invention will be described.

[Example 1-1]
First, an embodiment of the image forming unit of the first means will be described.
FIG. 2 shows the detailed configuration and operation of the image forming unit. Since the two image forming units I and II shown in FIG. 1 have the same configuration, the image forming unit I will be described as an example here.

  In FIG. 2, the photosensitive drum 101 is supported by the side plate 170 of the image forming unit I so as to be rotatable about the photosensitive drum axis. The C color unit 110 including the developing roller 111 on the upstream side of the photosensitive drum and the M color unit 120 including the developing roller 121 on the downstream side of the photosensitive drum are formed in an integral developing unit 150 serving as a holding unit. The side plate 170 is supported by the support means 155 so as to be rotatable about an axis parallel to the photosensitive drum axis, and can be moved in the direction of approaching and separating from the photosensitive drum 101 by the support means 156. It is supported. Further, the side plate 170 of the image forming unit I is urged by the urging means 157 in the direction approaching the photosensitive drum 101. Roller members 116 and 126 that can rotate on the developing roller shaft are provided at the end portions of the developing rollers 111 and 121 on the side plate 170, and the cam of the cam member 104 that has a rotating shaft parallel to the photosensitive drum shaft. By constantly contacting the surface 104a, the movement and rotation of the developing unit 150 due to the urging force of the urging means 157 is restricted. The photosensitive drum 101 and the developing unit 150 are supported and urged in the same configuration with respect to an image forming unit side plate (not shown) on the other end side in the axial direction of the photosensitive drum, and the roller member on the developing roller rotating shaft is the same. The movement is restricted by contacting the cam member.

  In the above configuration, the cam member 104 rotates at both axial ends of the photosensitive drum 101, and the distance from the cam member rotation shaft to the cam surface 104a with which the roller members 116 and 126 abut changes. The distance from the cam member rotating shaft to the developing roller shaft changes, and the distance from the developing roller shaft to the photosensitive drum shaft changes, so that the distance between the photosensitive drum and the developing roller, that is, the so-called developing gap changes. In FIG. 2A, the developing roller 111 disposed on the upstream side of the photosensitive drum has a developer in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and is located downstream of the photosensitive drum. In the developing roller 121 arranged on the side, the developer is not in contact with the photosensitive drum 101.

  In order to switch the developing roller 111 disposed on the upstream side of the photosensitive drum to a non-contact state with the developer on the photosensitive drum 101, the cam member 104 is rotated counterclockwise about the rotation axis. Shown in 2 (b). The developing roller 121 arranged on the downstream side of the photosensitive drum is in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and the developing roller arranged on the upstream side of the photosensitive drum. In 111, the developer is not in contact with the photosensitive drum 101.

  With the configuration as described above, the developing unit 150 that rotatably supports the two developing rollers 111 and 121 can be moved in the direction of approaching / separating from the photosensitive drum 101 and is parallel to the photosensitive drum axis. The roller members 116 and 126 at both ends of the two developing rollers 111 and 121 are supported by the cam members 104 at both axial ends parallel to the photosensitive drum shaft. By constantly contacting the cam surface 104a, it is possible to stably define the development gap with high accuracy.

[Example 1-2]
Next, an embodiment of the image forming unit of the third means will be described.
FIG. 3 shows the detailed configuration and operation. In FIG. 3, the description of the same configuration and operation as the first means and the configuration of FIG. 2 is omitted.

In FIG. 3A, the developing roller 121 disposed on the downstream side of the photosensitive drum has a developer in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and the upstream side of the photosensitive drum. In the developing roller 111 arranged on the side, the developer is not in contact with the photosensitive drum 101.
Here, in order to switch from color image output to monochrome image output, it is necessary to deactivate the two developing rollers 111 and 121 of the image forming unit I on the side not including the Bk color developing roller.

  FIG. 3 shows a state in which the developing roller 121 arranged on the downstream side of the photosensitive drum is rotated clockwise around the rotation axis of the cam member 104 in order to switch the developer to a non-contact state with respect to the photosensitive drum 101. Shown in (b). The developing roller 121 arranged on the downstream side of the photosensitive drum is in a non-contact state with respect to the photosensitive drum 101 with respect to the photosensitive drum 101 at a predetermined development gap, and is arranged on the upstream side of the photosensitive drum. In the developed roller 111, the developer is not in contact with the photosensitive drum 101.

  Next, when switching from monochrome image output to color image output, the developing roller 111 arranged on the upstream side of the photosensitive drum is switched to a state in which the developer is in contact with the photosensitive drum 101. Further, FIG. 3C shows a state in which it is further rotated in the clockwise direction. The developing roller 111 disposed on the upstream side of the photosensitive drum is in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and the developing roller disposed on the downstream side of the photosensitive drum. In 121, the developer is not in contact with the photosensitive drum 101.

When the operation of the image forming unit I including the C / M color developing unit 150 is stopped at the time of outputting a black and white image, the conventional method described in Patent Document 6 provides a state in which both developing rollers are in a non-developing state. For this reason, when one developing roller is in the developing state, the other developing roller is in a state of being more distant from the photoreceptor than necessary, and the size of the apparatus and the development state switching time are inevitably increased.
On the other hand, in this embodiment, the developing unit 150 that rotatably supports the two developing rollers 111 and 121 is configured to be movable in the direction approaching and separating from the photosensitive drum 101. Even in the above-described case, the developing roller retracting interval can be minimized, and the image forming unit can be downsized and the developing switching operation can be speeded up.

[Example 1-3]
Next, an embodiment of the image forming unit of the fourth and fifth means will be described.
FIG. 4 shows the detailed configuration and operation. In FIG. 4, the description of the first means and the configuration / operation equivalent to the configuration of FIG. 2 is omitted.

  In FIG. 4A, the developing roller 111 disposed on the upstream side of the photosensitive drum has a developer in contact with the photosensitive drum 101 at a predetermined developing gap with respect to the photosensitive drum 101, and at the downstream side of the photosensitive drum. In the developing roller 121 arranged on the side, the developer is not in contact with the photosensitive drum 101.

  FIG. 4 shows a state in which the developing roller 121 arranged on the downstream side of the photosensitive drum is rotated clockwise around the rotation axis of the cam member 104 in order to switch the developer to the photosensitive drum 101 in contact with the developer. Shown in b). The developing roller 121 arranged on the downstream side of the photosensitive drum is in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and the developing roller arranged on the upstream side of the photosensitive drum. Also in 111, the developer is in contact with the photosensitive drum 101.

  In order to switch the developing roller 111 arranged on the upstream side of the photosensitive drum to a state in which the developer is not in contact with the photosensitive drum 101, the cam member 104 is further rotated clockwise about the rotation axis. Shown in 4 (c). The developing roller 121 arranged on the downstream side of the photosensitive drum is in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and the developing roller arranged on the upstream side of the photosensitive drum. In 111, the developer is not in contact with the photosensitive drum 101.

  In the present exemplary embodiment, the development unit 150 that rotatably supports the two development rollers 111 and 121 can be effectively utilized by being configured so as to be movable toward and away from the photosensitive drum 101. The cam member 104 is formed so that the photosensitive member load fluctuation accompanying the completion of switching of the roller from the non-development state to the development state and the photosensitive member load fluctuation accompanying the start of switching from the development state to the non-development state are close to each other. Thus, when an image is formed (transferred) from the photosensitive drum 101 onto the intermediate transfer belt 105, an area where an image cannot be formed on the intermediate transfer belt 105 can be reduced. The forming apparatus can be reduced in size and cost. In addition, by increasing the rigidity of the intermediate transfer belt 105, it is possible to prevent elongation, vibration, and the like, and to achieve high image quality of the output image.

  Also, at this point, the switching of the developing roller to be developed from the non-development state to the development state is completed, and at the same time, the development roller of the developing roller that has been developed is started to switch from the non-development state to the non-development state. The intermediate transfer belt is formed by forming the cam member 104 so that the photosensitive member load fluctuation accompanying the completion of switching to the developing state and the photosensitive member load fluctuation accompanying the start of switching from the developing state to the non-developing state occur at the same timing. The area on which no image can be formed is minimized, and the intermediate transfer belt 105 can be greatly reduced in size and cost can be greatly reduced. Further, the intermediate transfer belt 105 can be further increased in rigidity and stretched. Vibrations and the like can be prevented more reliably, and the output image can be greatly improved in image quality.

  In particular, when the developing roller is brought into contact with the photosensitive drum during the developing operation as in the one-component developing method, the developing color switching operation from the non-developing state where the developing roller comes into contact with the photosensitive drum to the developing state is completed. The effect of this configuration is great because the influence of both the instant of time and the instant of starting the development color switching operation from the development state in which the developing roller is separated from the photosensitive drum to the non-development state is large.

[Example 1-4]
Next, an embodiment of the image forming unit of the sixth means will be described.
FIG. 5 shows the detailed configuration and operation. In FIG. 5, the description of the configuration and operation equivalent to the configuration of the first means and FIG. 2 is omitted.

  The roller members 116 and 126 at the end of the developing roller always contact the cam surface 104b of the cam member 104 supported so as to be rotatable coaxially with the photosensitive drum shaft, thereby restricting the movement of the developing rollers 111 and 121. , The distance from the photosensitive drum 101 (development gap) is defined.

  In FIG. 5A, the developing roller 111 disposed on the upstream side of the photosensitive drum has a developer in contact with the photosensitive drum 101 at a predetermined developing gap with respect to the photosensitive drum 101, and is downstream of the photosensitive drum. In the developing roller 121 disposed on the side, the developer is not in contact with the photosensitive drum 101.

  FIG. 5 shows a state in which the developing roller 121 disposed on the downstream side of the photosensitive drum is rotated counterclockwise about the rotation axis so that the developer contacts the photosensitive drum 101 with the developer. Shown in (b). The developing roller 121 arranged on the downstream side of the photosensitive drum is in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and the developing roller arranged on the upstream side of the photosensitive drum. In 111, the developer is not in contact with the photosensitive drum 101.

  In the above-described configuration, the cam member 104 that defines the distance between the photosensitive drum and the developing roller is provided on the same axis as the photosensitive drum, so that the number of parts that defines the developing gap that is the distance between the developing roller and the photosensitive drum is reduced. It is possible to improve the development gap with high accuracy by reducing the size, and it is possible to realize space saving by simplifying the configuration and cost reduction by reducing the number of parts.

[Example 1-5]
Next, an embodiment of the image forming unit of the seventh means will be described.
FIG. 6 shows the detailed configuration / operation. In FIG. 6, the description of the same configuration and operation as the first means and the configuration of FIG. 2 is omitted.

  FIG. 6A shows the developing roller driving state in the developing state of FIG. A drive gear 500G is fixed to a drive shaft 500S coupled to a motor (not shown) as a drive source provided on the apparatus main body side. The drive gear 500G is connected to a gear 111G disposed on the shaft 111S of the developing roller 111 via a drive transmission gear 501G that is an intermediate idler gear that is rotatably disposed on an axis parallel to the photosensitive drum rotation shaft 101S. It is connected. When the drive shaft 500S is driven by the motor, the gear 111G is driven via the drive gear 500G and the drive transmission gear 501G, and the developing roller 111 rotates. The drive gear 500G is connected to a drive transmission gear 502G that is an intermediate idler gear rotatably disposed on an axis parallel to the photosensitive drum rotation shaft 101S. At this time, the drive transmission gear 502G is developed. Since it is not connected with the gear 121G disposed on the shaft 121S of the roller 121, the developing roller 121 does not rotate even when the drive shaft 500S is driven by the motor.

  FIG. 6B shows the developing roller driving state in the developing state of FIG. The drive gear 500G is connected to a gear 121G disposed on the shaft 121S of the developing roller 121 via a drive transmission gear 502G that is rotatably disposed on an axis parallel to the photosensitive drum rotation shaft 101S. When the drive shaft 500S is driven by the motor, the gear 121G is driven via the drive gear 500G and the drive transmission gear 502G, and the developing roller 121 rotates. At this time, the drive transmission gear 501G connected to the drive gear 500G is not connected to the gear 111G disposed on the shaft 111S of the developing roller 111, so that even if the drive shaft 500S is driven by the motor, the developing roller 111 Does not rotate.

  Here, when driving gear 500G is driven in the direction of arrow a to drive drive gear 501G or 502G in the direction of arrow b, and gear 111G or 121G on the developing roller shaft is driven in the direction of arrow c, gear 111G or The force d in consideration of the effect of the pressure angle of the gear received by 121G is a component dx in the contact / separation direction between the roller member supported by the developing roller that receives the driving force and the cam member provided on the photosensitive drum shaft. The developing rollers 111 and 121 receive a driving force in the roller member-cam member contact / separation direction. The direction of the force of the roller member-cam member contact / separation direction component dx is determined by the positional relationship between the developing roller gears 111G and 121G and the drive transmission gears 501G and 502G. On the other hand, the position of the drive transmission gears 501G and 502G with respect to the gears 111G and 121G on the developing roller shaft is determined by the direction of the force of the roller member-cam member approaching / separating direction component of the driving force received by the developing roller in the developing roller driving state. By setting the roller member to a position that coincides with the direction in which the roller member is brought into contact with the cam member, the movement of the roller in the roller-cam member contact / separation direction by the developing roller driving force is restricted by the cam member 104. In addition, it is possible to reliably prevent the developing roller position from being changed with respect to the photosensitive drum 101 and to suppress the urging force required for the urging means.

  With the configuration as described above, it is possible to switch the development function by changing the development gap and the development drive switching by changing the gear transmission state with the development roller drive source with the same configuration and operation, thereby reducing the size and cost of the apparatus. Can be realized, and the development gap and the development roller gear transmission state are defined by the cam member 104 that restricts the roller member-cam member direction movement at both ends of the development roller at all times. In addition, since it is possible to prevent fluctuations in the rotational load and shock / vibration of the photosensitive drum during development switching, it is possible to improve the image quality of the output image and improve the reliability of the apparatus.

[Example 1-6]
Next, an embodiment of the image forming unit of the eighth means will be described.
7 and 8 show the detailed configuration and operation. 7 and 8, the description of the same configuration and operation as those of the first means and the configuration of FIG. 2 is omitted.

  FIG. 7 shows the developing roller driving state in the developing state of FIG. A driving side coupling portion 511a at one end of the driving force transmitting means 511 is coaxially connected to a driving shaft 510 connected to a driving source provided on the apparatus main body side. The driving side connecting portion 511a of the driving force transmitting means 511 transmits the rotational driving force to the driven side connecting portion 511c that is coaxially connected to the shaft 111s of the developing roller 111 via the intermediate member 511b, and serves as a driving source. The developing roller 111 rotates by being driven to rotate. Similarly, a driving side connecting portion 521a at one end of the driving force transmitting means 521 is coaxially connected to a driving shaft 520 connected to another driving source. The driving side connecting portion 521a of the driving force transmitting means 521 can transmit the rotational driving force to the driven side connecting portion 521c coaxially connected to the shaft 121S of the developing roller 121 via the intermediate member 521b. Since the drive source has stopped rotating, the developing roller 121 has stopped rotating.

  FIG. 8 shows the developing roller driving state in the developing state of FIG. The drive shaft 520 is connected to the driven side connecting portion 521c coaxially connected to the shaft 121S of the developing roller 121 via the intermediate member 521b from the driving side connecting portion 521a of the driving force transmitting means 521 connected coaxially. The developing roller 121 is rotated by transmitting the rotational driving force and rotationally driving the driving source. Similarly, the drive shaft 510 is connected on the driven side connected coaxially to the shaft 111S of the developing roller 111 via the intermediate member 511b from the drive side connecting portion 511a of the driving force transmitting means 511 connected coaxially. Although the rotational driving force can be transmitted to the part 511c, the developing roller 111 stops rotating because the driving source is stopped rotating.

  Here, the driving force transmission means 511, 521 are the rotation centers of the driven side connecting portions 511b, 521b connected to the developing roller shaft with respect to the rotation center shafts of the driving side connecting portions 511a, 521a connected to the driving shaft. The shaft is configured to be movable in a direction orthogonal to the respective rotation center axes while maintaining the state in which the respective rotation axis center axes are parallel to each other. For this reason, the rotation of the cam member 104 allows the developing rollers 111 and 121 to move with respect to the drive shaft between a position where the distance from the photosensitive drum 101 becomes a specified developing gap and a position where the developing roller 111 and 121 are not developed. Become.

  FIG. 9 shows a configuration for realizing the function of such driving force transmission means. In the figure, a drive side connecting portion 511a connected coaxially to a drive shaft is supported so as to be rotatable about a shaft 511d with respect to a support member 511e having a shaft 511d orthogonal to the drive shaft rotation center axis. Yes. The support member 511e has a shaft 511f orthogonal to the shaft 511d, and the intermediate member 511b is supported by the support member 511e so as to be rotatable about the shaft 511f. The driven side connecting portion 511c connected to the developing roller shaft is supported by a supporting member 511e having a shaft 511d orthogonal to the developing roller shaft rotation center axis so as to be rotatable about the shaft 511d. The support member 511e has a shaft 511f orthogonal to the shaft 511d, and the intermediate member 511b is supported by the support member 511e so as to be rotatable about the shaft 511f.

  With the above configuration, the drive shaft and the developing roller shaft are coupled so that the rotational driving force can be transmitted, and the developing roller shaft rotation center axis is parallel to the rotation shaft center axis with respect to the drive shaft rotation center axis. It is possible to move in the direction orthogonal to the respective rotation center axes while maintaining the state.

  FIG. 10 shows another configuration for realizing the function of the driving force transmitting means. In the figure, a drive side connecting portion 511a that is coaxially connected to the drive shaft has a rail portion 511g in a direction orthogonal to the drive shaft rotation center axis. The intermediate member 511b has a groove portion 511h that mates with the rail portion 511g of the drive side connecting portion 511a, and is supported to be slidable in a direction parallel to the rail portion 511g. The driven side connecting portion 511c connected to the developing roller shaft has a rail portion 511i in a direction orthogonal to the developing roller shaft rotation center axis. The intermediate member 511b is engaged with the rail portion 511i of the driven side connecting portion 511c and has a groove portion 511j in a direction perpendicular to the groove portion 511h, and is supported to be slidable in a direction parallel to the groove portion rail portion i. ing.

  With the above configuration, the drive shaft and the developing roller shaft are coupled so that the rotational driving force can be transmitted, and the developing roller shaft rotation center axis is parallel to the rotation shaft center axis with respect to the drive shaft rotation center axis. It is possible to move in the direction orthogonal to the respective rotation center axes while maintaining the state. In this configuration, compared with the configuration of FIG. 9, the number of parts can be reduced and the space can be saved, and the apparatus can be downsized and the cost can be reduced.

  In the configuration of the driving force transmission means as shown in FIGS. 9 and 10, the driving side connecting portion of the driving force transmission means is driven coaxially with the driving shaft by driving the driving shaft. Further, the developing roller shaft is driven coaxially with the driven side connecting portion of the driving force transmitting means. In this case, the driving force that the developing roller receives in the approaching / separating direction of the photosensitive drum is very small. It can be surely prevented. Here, the developing roller shaft can move in the direction orthogonal to the respective rotation center axes with respect to the drive shaft, but the positional relationship is determined in the developing state, that is, the distance between the developing roller and the photosensitive drum. By defining that the developing roller shaft and the drive shaft are coaxial, when the is at the position where the development gap is at the specified development gap, the driving force in the proximity and separation direction of the photosensitive drum received by the developing roller is minimized, and the greatest effect Can be obtained.

  With the configuration as described above, the development gap is defined by the cam member that always restricts the movement of the photosensitive member in the proximity / separation direction at both ends of the development roller, so that stable definition with high accuracy is possible and development switching is possible. It is possible to prevent fluctuations in the rotational load and impact / vibration of the photosensitive drum, and to improve the image quality of the output image and improve the reliability of the apparatus.

  The configuration of FIGS. 9 and 10 is exemplified as the driving force transmission means applicable to the present embodiment. However, the configuration is not limited to this, and development is performed with respect to the rotation center axis of the driving side coupling portion that is coaxially coupled to the driving shaft. Driving force that can move in the direction perpendicular to each rotation center axis while maintaining the rotation axis center axis of the driven side coupling portion coaxially connected to the roller axis in a state where each rotation axis center axis is parallel. The effect of the eighth means can be realized by using the transmission means.

[Example 1-7]
Next, an embodiment of the image forming unit of the ninth means will be described.
11 and 12 show the detailed configuration and operation. In FIGS. 11 and 12, the description of the configuration and operation equivalent to the configuration of the first means and FIG. 2 is omitted.

  FIG. 11 shows the developing roller driving state in the developing state of FIG. A drive-side transmission means 511a at one end of the drive force transmission means 511 is coaxially connected to a drive shaft 510 connected to a drive source provided on the apparatus main body side. Driven side transmission means 511c is coaxially connected to the shaft 111s of the developing roller 111. Here, the driving force transmission means 511 is in a driving force transmission state, and when the driving shaft 510 rotates by driving the driving source, the driving side transmission means 511a transmits the rotational driving force to the driven side transmission means 511c. The developing roller 111 rotates. Similarly, the drive-side transmission means 521a at one end of the drive force transmission means 521 is coaxially connected to the drive shaft 520 connected to a common drive source. Driven side transmission means 521c is coaxially connected to the shaft 121S of the developing roller 121. Here, the driving force transmission means 521 is in a driving force transmission release state, and the developing roller 121 does not rotate even when the driving source is driven and the driving shaft 520 rotates.

  FIG. 12 shows the developing roller driving state in the developing state of FIG. The driving side connecting portion 521a of the driving force transmitting means 521 coaxially connected to the driving shaft 520 and the driven side connecting portion 521c coaxially connected to the shaft 121S of the developing roller 121 are in a driving force transmitting state. When the drive shaft 520 is rotated by driving the drive source, the drive-side transmission unit 521a transmits the rotational driving force to the driven-side transmission unit 521c, and the developing roller 121 rotates. Similarly, the driving side connecting portion 511a of the driving force transmitting means 511 connected coaxially to the driving shaft 510 and the driven side connecting portion 511c coaxially connected to the shaft 111S of the developing roller 111 are transmitted with driving force. Even when the drive source is driven and the drive shaft 510 is rotated, the developing roller 111 does not rotate.

  Here, the driving force transmission means 511, 521 are the rotation centers of the driven side connecting portions 511b, 521b connected to the developing roller shaft with respect to the rotation center shafts of the driving side connecting portions 511a, 521a connected to the driving shaft. When the driving force transmission is released, the shafts are configured to be movable in a direction perpendicular to the respective rotation center axes while maintaining the respective rotation axis center axes in a parallel state. For this reason, the rotation of the cam member 104 allows the developing rollers 111 and 121 to move with respect to the drive shaft between a position where the distance from the photosensitive drum 101 becomes a specified developing gap and a position where the developing roller 111 and 121 are not developed. Become.

  FIG. 13 shows a configuration for realizing such a function of the driving force transmission means. As shown in the figure, the drive-side transmission means 511a is formed with a drive force transmission portion 511b having a plurality of planes parallel to the rotation axis. In the driven side transmission means 511c, a driving force transmitted portion 511d having a plurality of planes parallel to the rotation axis is formed. Further, the roller member 116 is in contact with the cam surface 104a to define the development gap so that the developing roller 111 is in a developing state with respect to the photosensitive drum 101. At this time, the driving side transmission unit 511a and the driven side transmission are defined. The rotation axis of the means 511c is coaxial.

  The drive-side transmission means 511a is urged in a direction in which the integrally formed rotation axis direction defining portion 511e abuts on the cam surface 104c formed on the cam member 104, and the rotation axis direction defining portion 511e is By contacting the cam surface 104b, it is defined that the position of the drive-side transmission means 511a relative to the driven-side transmission means 511c is in the driving force transmission state.

When the driving side transmission means 511a is driven in this state, the driving force transmission portion 511b of the driving side transmission means 511a is in contact with the driving force transmission portion 511d of the driven side transmission means 511c to transmit the rotational driving force. The developing roller 111 is rotated by rotating the driving source.
Similarly, the driving side transmission means 521a is also provided with a driving force transmission portion 521b. Similarly, a driving force transmitted portion 521d is formed in the driven side transmission means 521c.

  Next, the roller member 126 abuts on the cam surface 104a to define the developing gap so that the developing roller 121 is not developed with respect to the photosensitive drum 101. At this time, the driving side transmission unit 521a and the driven side are defined. The rotation axis of the transmission means 521c is not coaxial.

  The drive-side transmission means 521a is urged in the direction in which the integrally formed rotation axis direction defining portion 521e abuts on the cam surface 104c formed on the cam member 104, and the rotation axis direction defining portion 521e is By contacting the cam surface 104b, it is defined that the rotational direction position of the driving side transmission means 521a with respect to the driven side transmission means 521c is in a driving force transmission release state.

  Even if the driving side transmission means 521a is driven in this state, the driving force transmission portion 521b of the driving side transmission means 521a does not contact the driving force transmission portion 521d of the driven side transmission means 521c, and the rotational driving force is transmitted. Therefore, the developing roller 121 does not rotate even if the driving source is driven to rotate.

  FIG. 14 shows a state where the cam member is rotated in order to switch the developing function. The roller member 126 abuts on the cam surface 104a to define the development gap so that the developing roller 121 is in a developing state with respect to the photosensitive drum 101. At this time, the driving side transmission unit 521a and the driven side transmission unit 521c are defined. The axis of rotation is on the same axis.

  Further, in the driving side transmission means 521a, the rotational axis direction position of the driving side transmission means 521a with respect to the driven side transmission means 521c becomes a driving force transmission state by the rotation axis direction defining portion 521e coming into contact with the cam surface 104c. It stipulates that

  When the driving side transmission means 521a is driven in this state, the driving force transmission part 521b of the driving side transmission means 521a contacts the driving force transmission part 521d of the driven side transmission means 521c to transmit the rotational driving force. The developing roller 121 is rotated by rotating the driving source.

  Next, the roller member 116 is in contact with the cam surface 104a to define the development gap so that the developing roller 111 is not developed with respect to the photosensitive drum 101. At this time, the driving side transmission unit 511a and the driven side are defined. The rotation axis of the transmission means 511c is not coaxial.

  The drive-side transmission means 511a is urged in a direction in which the integrally formed rotation axis direction defining portion 511e abuts on the cam surface 104b formed on the cam member 104, and the rotation axis direction defining portion 511e is By contacting the cam surface 104c, it is defined that the rotational direction position of the driving side transmission means 511a with respect to the driven side transmission means 511c is in a driving force transmission release state.

  Even if the driving side transmission means 511a is driven in this state, the driving force transmission portion 511b of the driving side transmission means 511a does not contact the driving force transmission portion 511d of the driven side transmission means 511c, and the rotational driving force is transmitted. Therefore, the developing roller 111 does not rotate even if the drive source is driven to rotate.

  Here, the driving force transmission means is configured to have a degree of freedom of movement in the direction perpendicular to the rotation axis of the developing roller with respect to the drive shaft only when in the drive transmission release state, so that the development gap only in the reliable drive force transmission release state. It is desirable to form the cam surface so as to perform the development / non-development state switching operation.

  Therefore, the cam member 104 starts and ends the operation in which the driving force transmitting means on the one developing roller side changes from the driving force transmitting state to the driving force transmitting released state by the rotation, and then the cam member 104 and the one developing roller are exposed to light. The operation of changing the interval between the photosensitive drums from the development state to the non-development state is started, and after the operation of changing the interval between the other development roller and the photosensitive drum from the non-development state to the development state is completed, The driving force transmission unit starts and ends the operation of changing from the driving force transmission release state to the driving force transmission state, and the other developing roller side driving force transmission unit changes from the driving force transmission state to the driving force transmission release state. After starting and ending the operation, the operation of changing the distance between the other developing roller and the photosensitive drum from the developing state to the non-developing state is started, and the interval between the one developing roller and the photosensitive drum is not developed. After completing the operation of changing to the developing state, the driving force transmitting means on one developing side starts and ends the operation of changing from the driving force transmission releasing state to the driving force transmitting state, thereby forming a cam surface. Stable development switching can be realized.

  Next, embodiments of the image forming unit according to the second means and the tenth to fourteenth means of the present invention will be described.

[Example 2-1]
First, a configuration example of the image forming unit of the second means will be described.
FIG. 15 shows the detailed configuration and operation of the image forming unit. Since the two image forming units I and II shown in FIG. 1 have the same configuration, the image forming unit I will be described as an example here.

  In FIG. 15, the photosensitive drum 101 is supported by the side plate 170 of the image forming unit I so as to be rotatable about the photosensitive drum axis. The C color unit 110 including the developing roller 111 on the upstream side of the photosensitive drum and the M color unit 120 including the developing roller 121 on the downstream side of the photosensitive drum are formed in an integral developing unit 150 serving as a holding unit. The side plate 170 is supported by the support unit 155 so as to be rotatable about an axis parallel to the photosensitive drum axis, and is supported by the support unit 156 so as to be movable in the direction of approaching and separating from the photosensitive drum 101. ing. Further, the side plate 170 of the image forming unit I is urged by the urging means 157 in the direction approaching the photosensitive drum 101. Roller members 116 and 126 that can rotate on the developing roller shaft are provided at the end portions of the developing rollers 111 and 121 on the side plate 170, and the cam of the cam member 104 that has a rotating shaft parallel to the photosensitive drum shaft. By constantly contacting the surface 104a, the movement and rotation of the developing unit 150 due to the urging force of the urging means 157 is restricted. The photosensitive drum 101 and the developing unit 150 are supported and urged by a similar configuration with respect to an image forming unit side plate (not shown) on the other end side in the axial direction of the photosensitive drum, and the roller member 116 on the rotating shaft of the developing roller. 126 are in contact with a similar cam member 104, and movement is restricted.

  In the above configuration, the cam member 104 rotates at both ends in the photosensitive drum axial direction, and the distance from the cam member rotating shaft to the cam surface 104a where the roller members 116 and 126 abut changes. The distance from the rotating shaft to the developing roller shaft changes, and the distance from the developing roller shaft to the photosensitive drum shaft changes, so that the distance between the photosensitive drum and the developing roller, that is, the so-called developing gap changes. In FIG. 15A, the developing roller 111 disposed on the upstream side of the photosensitive drum has a developer in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and the downstream side of the photosensitive drum. In the developing roller 121 arranged on the side, the developer is not in contact with the photosensitive drum 101.

  In order to switch the developing roller 111 disposed on the upstream side of the photosensitive drum to a state in which the developer is not in contact with the photosensitive drum 101, the cam member 104 is rotated counterclockwise about the rotation axis. It is shown in 15 (b). The developing roller 121 arranged on the downstream side of the photosensitive drum is in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and the developing roller arranged on the upstream side of the photosensitive drum. In 111, the developer is not in contact with the photosensitive drum 101.

  With the configuration as described above, the developing unit 150 that rotatably supports the two developing rollers 111 and 121 can be moved toward and away from the photosensitive drum 101 and is centered on an axis parallel to the photosensitive drum axis. The roller members 116 and 126 at both ends of the two developing rollers are always urged to the cam surfaces 104a of the cam members 104 at both ends in the axial direction parallel to the photosensitive drum shaft. By abutting, it is possible to stably define the development gap with high accuracy.

[Example 2-2]
Next, an embodiment of the image forming unit of the second and tenth means will be described.
FIG. 16 shows the detailed configuration / operation. In FIG. 16, the description of the same configuration / operation as that of FIGS. 1 and 15 is omitted.

The two conveying screws (reference numerals 112 and 113 in FIG. 1) for conveying the developer in the C color unit 110 are arranged outside of one end plate 170 of the C color unit 110 as shown in FIG. The shafts 112S and 113S are connected to each other via gears 112G and 113G fixed to the shafts 112S and 113S.
Similarly, the conveying screw and the developing roller 111 are also connected to each other via gears 112G and 111G fixed to the respective shafts 112S and 111S.

The conveying screws (reference numerals 122 and 123 in FIG. 1) in the M color unit 120 are also connected to each other via gears 122G and 123G fixed to the respective shafts 122S and 123S, as shown in FIG. .
Similarly, the conveying screw and the developing roller 121 are also connected to each other via gears 122G and 121G fixed to the respective shafts 122S and 121S.

  In FIG. 16A, the developing roller 111 arranged on the upstream side of the photosensitive drum is in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and at the downstream side of the photosensitive drum. In the developing roller 121 arranged on the side, the developer is not in contact with the photosensitive drum 101. A gear 500G is fixed to a drive shaft 500S connected to a drive source (for example, a motor (not shown)) provided on the image forming apparatus main body, and is rotatably supported by a rotation support unit 155 of the developing unit 150. It is connected to the conveying screw gear 113G via an idler gear 115G. Here, when the drive shaft 500S rotates in the direction of the arrow by driving the drive source, each gear rotates in the direction of the arrow to transmit the driving force, and the developing roller gear 111G rotates. An electromagnetic clutch (not shown) is provided between the gear 111G and the developing roller 111, and is configured to switch the rotation / stop of the developing roller 111 by energization / non-energization of the electromagnetic clutch. Thus, the developing roller 111 rotates. The idler gear 115G is connected to the conveying screw gear 123G. Here, when the drive shaft rotates by driving the drive source, each gear transmits a rotational driving force, and the developing roller gear 121G rotates. An electromagnetic clutch (not shown) is provided between the gear 121G and the developing roller 121, and is configured to switch the rotation / stop of the developing roller 111 by energization / non-energization of the electromagnetic clutch. Thus, the developing roller 121 does not rotate.

  In FIG. 16B, the developing roller 121 arranged on the downstream side of the photosensitive drum is in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and the upstream side of the photosensitive drum. In the developing roller 111 arranged on the side, the developer is not in contact with the photosensitive drum 101. An idler gear 115G that receives a driving force from a driving source provided on the apparatus main body side is connected to a conveying screw gear 113G. Here, when the drive shaft 500S rotates in the direction of the arrow in the drawing by driving the drive source, each gear rotates in the direction of the arrow in the drawing to transmit the driving force, and the developing roller gear 111G rotates. An electromagnetic clutch (not shown) is provided between the gear 111G and the developing roller 111, and is configured to switch the rotation / stop of the developing roller 111 by energization / non-energization of the electromagnetic clutch. Thus, the developing roller 111 does not rotate. The idler gear 115G is connected to the conveying screw gear 123G. Here, when the drive shaft rotates by driving the drive source, each gear transmits a rotational driving force, and the developing roller gear 121G rotates. An electromagnetic clutch (not shown) is provided between the gear 121G and the developing roller 121, and is configured to switch the rotation / stop of the developing roller 121 by energization / non-energization of the electromagnetic clutch. Thus, the developing roller 121 rotates.

  With the configuration as described above, the developing unit 150 that rotatably supports the two developing rollers 111 and 121 can be moved in the approaching / separating direction with respect to the photosensitive drum 101 and is centered on an axis parallel to the photosensitive drum axis. The roller members 116 and 126 at both ends of the two developing rollers are always urged to the cam surfaces 104a of the cam members 104 at both axial ends parallel to the photosensitive drum shaft. By abutting, it is possible to stably define the development gap with high accuracy.

  In order to realize high-quality image output, it is necessary to maintain the distance between the developing rollers 111 and 121 and the photosensitive drum 101, that is, a so-called developing gap with high accuracy in the developing state. When the developing unit 150 is rotated, if the developing unit 150 is considered as a rigid body, it is considered that the two developing rollers 111 and 121 and the photosensitive drum 101 always maintain a parallel relationship. However, since the developing unit 150 actually has a certain degree of elasticity, the driving force applied to the developing unit 150 in order to drive a rotating mechanism such as a developing roller is in a direction to twist the developing unit 150 about the rotation axis. When this occurs, the roller members 116 and 126 at both ends of the two developing rollers cannot always come into contact with the cam surfaces 104a of the cam members 104 at both ends in the axial direction parallel to the photosensitive drum shaft. It is difficult to maintain the parallel relationship of the photosensitive drums. However, in the second means, the driving force for driving the developing roller and the conveying screw is applied to the developing unit 150 via the idler gear 115G provided on the developing unit rotation shaft. The radius of action of the force in the direction of twisting around the dynamic axis is small and the influence is minimal. Therefore, it becomes easy to maintain the parallel relationship between the developing rollers 111 and 121 and the photosensitive drum 101.

  Here, the direction of the driving force acting on the idler gear 115G provided on the developing unit rotation shaft from the driving source is such that the roller members 116 and 126 on both ends of the two developing rollers with respect to the developing unit 150 as shown in FIG. By setting the position of the drive shaft so as to act in the direction in which the cam member 104 abuts on the cam surface 104a, the roller members 116 and 126 and the cam surface 104a can be stably abutted, and the two developing rollers It becomes possible to maintain the parallel relationship between 111 and 121 and the photosensitive drum 101 more reliably.

[Example 2-3]
Next, an embodiment of the image forming unit of the eleventh means will be described.
FIG. 17 shows the detailed configuration / operation. In FIG. 17, the description of the second and tenth means and the configuration and operation equivalent to those of FIGS. 15 and 16 are omitted.

  In FIG. 17A, the developing roller 111 disposed on the upstream side of the photosensitive drum is in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and at the downstream of the photosensitive drum. In the developing roller 121 arranged on the side, the developer is not in contact with the photosensitive drum 101. An idler gear 115G that receives a driving force from a gear fixed to a driving shaft coupled to a driving source provided on the image forming apparatus main body side is rotatably supported by a rotation support means 155 of the developing unit 150, and is idler. It is connected to a gear 113G fixed to the conveying screw shaft 113S via a gear 118G. Here, when the drive shaft rotates in the clockwise direction by driving the drive source, each gear transmits a rotational driving force, and the developing roller gear 111G rotates. A one-way clutch 119 is provided between the gear 111G and the developing roller 111, and the lock / idle state is switched according to the rotation direction, and the rotation / stop of the developing roller 111 is switched. The developing roller 111 rotates. The idler gear 115G is connected to a gear 123G fixed to the conveying screw shaft 123S. Here, when the drive shaft rotates in the clockwise direction by driving the drive source, each gear transmits a rotational driving force, and the developing roller gear 121G rotates. A one-way clutch 129 is provided between the gear 121G and the developing roller 121, and the lock / idle state is switched according to the rotation direction, and the rotation / stop of the developing roller 121 is switched. The developing roller 121 does not rotate.

  In FIG. 17B, the developing roller 121 disposed on the downstream side of the photosensitive drum is in contact with the photosensitive drum 101 at a predetermined developing gap with respect to the photosensitive drum 101, and the upstream side of the photosensitive drum. In the developing roller 111 disposed on the side, the developer is not in contact with the photosensitive drum 101. An idler gear 115G that receives a driving force from a gear fixed to a driving shaft coupled to a driving source provided on the image forming apparatus main body side is rotatably supported by a rotation support means 155 of the developing unit 150, and is idler. It is connected to a gear 113G fixed to the conveying screw shaft 113S via a gear 118G. Here, when the drive shaft rotates in the counterclockwise direction by driving the drive source in the reverse direction, each gear transmits a rotational drive force, and the developing roller gear 111G rotates. A one-way clutch 119 is provided between the gear 111G and the developing roller 111, and the lock / idle state is switched depending on the rotation direction, and the rotation / stop of the developing roller 111 is switched. The developing roller 111 does not rotate. The idler gear 115G is connected to a gear 123G fixed to the conveying screw shaft 123S. Here, when the drive shaft rotates in the counterclockwise direction by driving the drive source in the reverse direction, each gear transmits a rotational drive force, and the developing roller gear 121G rotates. A one-way clutch 129 is provided between the gear 121G and the developing roller 121, and the lock / idle state is switched depending on the rotation direction, and the rotation / stop of the developing roller 121 is switched. The developing roller 121 rotates.

  When one developing roller is rotating and working to develop the electrostatic latent image on the photosensitive drum, the other developing roller needs to stop rotating. A one-way clutch is provided in each drive gear train from the idler gear 115G provided on the rotation shaft of the developing unit to the two developing rollers 111 and 121. When the drive source is rotated in one direction, the idler gear 115G is connected to one developing roller. The one-way clutch provided in the drive gear train is in a rotating state, and the one-way clutch provided in the driving force gear train to the other developing roller is placed in a direction in which it is stopped. By disposing the one-way clutch provided in the driving gear train from the gear 115G to the other developing roller in the rotating state and the one-way clutch provided in the driving force gear train from the one developing roller in the direction of stopping. Without a mechanism that requires electric power, such as an electromagnetic clutch, with a simple configuration, the drive source In operation of only switching the direction of rotation, it is possible to realize the driving switching of two developing rollers 111 and 121.

[Example 2-4]
Next, an embodiment of the image forming unit of the twelfth means will be described.
FIG. 18 shows the detailed configuration / operation. In FIG. 18, the description of the second and tenth means and the configuration and operation equivalent to those of FIGS. 15 and 16 are omitted.

  In FIG. 18A, the developing roller 111 disposed on the upstream side of the photosensitive drum is in contact with the photosensitive drum 101 at a predetermined developing gap with respect to the photosensitive drum 101, and at the downstream side of the photosensitive drum. In the developing roller 121 disposed on the side, the developer is not in contact with the photosensitive drum 101. An idler gear 115G that receives a driving force from a gear fixed to a driving shaft coupled to a driving source provided on the image forming apparatus main body side is rotatably supported by a rotation support unit 155 of the developing unit 110. Via a gear 118G, it is connected to a gear 119G disposed on the conveying screw shaft 113S via a one-way clutch 119. A gear 113G is coaxially fixed to the gear 119G on the conveying screw shaft 113S, and the gear 113G is connected to the gears 112G and 111G. When the conveying screw rotates, the developing roller 111 also rotates at the same time. When stopped, the developing roller 111 also stops simultaneously.

  Here, when the drive shaft rotates in the clockwise direction by driving the drive source, each gear transmits a rotational driving force, and the gear 119G rotates. The one-way clutch 119 between the gear 119G and the conveying screw shaft 113S is configured to switch between a lock / idle state and a rotation / stop of the conveying screw depending on the rotation direction. In this case, the one-way clutch 119 is in a rotating state. The screw rotates and the developing roller 111 rotates. The idler gear 115G is connected to a gear 129G disposed on the conveying screw shaft 123S via a one-way clutch 129. A gear 123G is coaxially fixed to the gear 129G on the conveying screw shaft 123S, and the gear 123G is connected to the gears 122G and 121G. When the conveying screw rotates, the developing roller 121 also rotates at the same time, and the conveying screw rotates. When stopped, the developing roller 121 is also stopped simultaneously.

  Here, when the drive shaft rotates in the clockwise direction by driving the drive source, each gear transmits a rotational driving force, and the gear 129G rotates. The one-way clutch 129 between the gear 129G and the shaft 123S of the conveying screw 123 is configured to switch between a lock / idle state and a rotation / stop of the conveying screw 123 depending on the rotation direction. In this case, the one-way clutch 129 is in a stopped state. The conveying screw 123 does not rotate, and the developing roller 121 does not rotate.

  In FIG. 18B, the developing roller 121 arranged on the downstream side of the photosensitive drum is in contact with the photosensitive drum 101 at a predetermined developing gap with respect to the photosensitive drum 101, and the upstream side of the photosensitive drum. In the developing roller 111 arranged on the side, the developer is not in contact with the photosensitive drum 101. An idler gear 115G that receives a driving force from a gear fixed to a driving shaft coupled to a driving source provided on the image forming apparatus main body side is rotatably supported by a rotation support means 155 of the developing unit 150, and is idler. Via a gear 118G, it is connected to a gear 119G arranged on the conveying screw shaft 113S via a one-way clutch 119. A gear 113G is coaxially fixed to the gear 119G on the conveying screw shaft 113S, and the gear 113G is connected to the gears 112G and 111G. When the conveying screw rotates, the developing roller 111 also rotates at the same time. When stopped, the developing roller 111 also stops simultaneously.

  Here, when the drive shaft rotates counterclockwise by driving the drive source in the reverse direction, each gear transmits a rotational driving force, and the gear 119G rotates. The one-way clutch 119 between the gear 119G and the conveying screw shaft 113S is configured to switch between a lock / idle state and a rotation / stop of the conveying screw depending on the rotation direction. In this case, the one-way clutch 119 is in a stopped state. The screw does not rotate and the developing roller 111 does not rotate. The idler gear 115G is connected to a gear 129G disposed on the conveying screw shaft 123S via a one-way clutch 129. A gear 123G is coaxially fixed to the gear 129G on the conveying screw shaft 123S, and the gear 123G is connected to the gears 122G and 121G. When the conveying screw rotates, the developing roller 121 also rotates at the same time, and the conveying screw rotates. When stopped, the developing roller 121 is also stopped simultaneously.

  Here, when the drive shaft rotates counterclockwise by driving the drive source in the reverse direction, each gear transmits a rotational driving force, and the gear 129G rotates. The one-way clutch 129 between the gear 129G and the conveying screw shaft 123S is configured to switch between a lock / idle state and a rotation / stop of the conveying screw depending on the rotation direction. In this case, the one-way clutch 129 is in a rotating state. The screw rotates and the developing roller 121 rotates.

  When one color unit (developing device) of the developing unit 150 is in developing operation, the developing roller needs to stop rotating in the non-operating color unit (developing device). It is desirable that the agent stirring and conveying mechanism also stops rotating. Since the developer agitation and transport operation imposes a load on the developer and causes a decrease in the life of the developer, it is possible to extend the life of the developer by not performing unnecessary development agitation operation in a non-operating developer. It becomes. A one-way clutch is connected to the gear train between the idler gear 115G provided on the developing unit rotating shaft and the two simultaneous drive gear trains so that the developer stirring and transport mechanism such as the developing roller and the transport screw are driven simultaneously. When the drive source rotates in one direction, the one-way clutch provided between the idler gear 115G and one simultaneous drive gear train is locked, and the one-way clutch provided between the other simultaneous drive gear train Are arranged in the direction of idling, and when the drive source rotates in the other direction, the one-way clutch provided between the idler gear 115G and the other simultaneous drive gear train is locked, The one-way clutch provided between them is arranged in the direction that causes idling so that it can be configured in a simple manner and is not in operation. Not only the developing roller in the vessel, the developer agitating and conveying mechanism also stop the rotation becomes possible.

[Example 2-5]
Next, an embodiment of the image forming unit of the thirteenth means will be described.
19 and 20 show the detailed configuration and operation. 19 and 20, the description of the second and tenth to twelfth means and the configuration and operation equivalent to those of FIGS. 15 to 18 are omitted.

  In FIG. 19A, the developing roller 121 disposed on the downstream side of the photosensitive drum has a developer in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101 and an upstream side of the photosensitive drum. In the developing roller 111 arranged on the side, the developer is not in contact with the photosensitive drum 101. The state of the drive system at this time is shown in FIG. 20 (a), which is the same state as in FIG. 17 (b).

  In FIG. 20A, an idler gear 115G that receives a driving force from a gear 500G fixed to a driving shaft 500S coupled to a driving source provided on the image forming apparatus main body side is provided on a rotation support unit 155 of the developing unit 150. On the other hand, it is supported rotatably. Here, the rotation center of the drive shaft 500S and the gear 500G is supported by the support means 156 so that the developing unit 150 can move in the proximity and separation direction of the photosensitive drum with respect to the rotation support means 155 and the rotation center of the idler gear 115G. It is located in a direction perpendicular to the movable direction.

Next, in order to switch from color image output to monochrome image output, the two developing rollers 111 and 121 of the image forming unit I on the side that does not include the Bk developing roller need to be inoperative.
FIG. 19 shows a state in which the developing roller 121 arranged on the downstream side of the photosensitive drum is rotated clockwise about the rotation axis in order to switch the developing roller 121 to a non-contact state with respect to the photosensitive drum 101. Shown in (b). The developing roller 121 arranged on the downstream side of the photosensitive drum is in a non-contact state with respect to the photosensitive drum 101 with respect to the photosensitive drum 101 at a predetermined development gap, and is arranged on the upstream side of the photosensitive drum. In the developed roller 111, the developer is not in contact with the photosensitive drum 101. The state of the drive system at this time is shown in FIG.

  In FIG. 20B, the developing unit 150 has a photosensitive member in a movable direction in which the developing unit 150 is supported by the supporting unit 156 so as to be movable toward and away from the photosensitive drum as compared with the state of FIG. It moves in a direction away from the drum 101. Therefore, the gear 500G fixed to the drive shaft 500S coupled to the drive source provided on the image forming apparatus main body side and the idler gear 115G supported rotatably with respect to the rotation support means 155 of the developing unit 150 are provided. The state is shifted from the meshing position in the driving state. Here, in the engaged state, the rotation center of the drive shaft 500S and the gear 500G is set in the direction of approaching and separating the photosensitive drum by the support unit 156 with respect to the rotation support unit 155 and the rotation center of the idler gear 115G. Whereas the developing unit 150 moves in a direction away from the photosensitive drum, the developing unit 150 moves in a direction perpendicular to the movable direction supported so as to be movable, the rotation center of the drive shaft 500S and the gear 500G, and the rotation. Since the distance between the rotation support means 155 and the rotation center of the idler gear 115G is increased, the gear 500G is stable without hindering movement of the idler gear 115G and the developing unit 150 in the direction away from the photosensitive drum. Operation is possible. Here, the positional conditions of the rotation center of the drive shaft 500S and the gear 500G and the rotation center of the rotation support means 155 and the idler gear 115G necessary for realizing this operation are not limited to this, and the drive shaft 500S and the gear This can be realized by setting 500G to a position that allows the idler gear 115G and the developing unit 150 to move away from the photosensitive drum from the driving state.

When the operation of the image forming unit I including the C and M color developing units 150 is stopped when outputting a black and white image, the conventional method described in Patent Document 6 described above is in a state where both developing rollers are in a non-developing state. For this reason, when one developing roller is in the developing state, the other developing roller is more distant from the photoreceptor than necessary, and the size of the apparatus and the development state switching time are inevitably increased.
On the other hand, in this embodiment, it is effectively used that the developing unit 150 that rotatably supports the two developing rollers 111 and 121 is configured to be movable in the approaching / separating direction with respect to the photosensitive drum 101. Even in the above-described case, the retraction interval of the developing roller can be minimized, and the image forming unit can be downsized and the development switching operation can be performed at high speed.

[Example 2-6]
Next, an embodiment of the image forming unit of the fourteenth means will be described.
21 and 22 show the detailed configuration and operation. 21 and 22, the description of the second and tenth to twelfth means and the configuration and operation equivalent to those of FIGS. 15 to 18 are omitted.

  In FIG. 21A, the developing roller 111 disposed on the upstream side of the photosensitive drum has a developer in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and downstream of the photosensitive drum. In the developing roller 121 arranged on the side, the developer is not in contact with the photosensitive drum 101. The state of the drive system at this time is shown in FIG. 22 (a), which is the same state as FIG. 17 (a).

  In FIG. 22A, an idler gear 115G receiving a driving force from a gear 500G fixed to a driving shaft 500S coupled to a driving source provided on the apparatus main body side rotates with respect to a rotation support means 155 of the developing unit 150. Supported as possible. Here, the rotation center of the drive shaft 500S and the gear 500G is supported by the support means 156 so that the developing unit 150 can move in the proximity and separation direction of the photosensitive drum with respect to the rotation support means 155 and the rotation center of the idler gear 115G. It is located in a direction perpendicular to the movable direction.

  FIG. 21B shows a state in which the developing roller 121 arranged on the downstream side of the photosensitive drum is rotated clockwise about the rotation axis in order to switch the developing roller 121 to the photosensitive drum 101 in contact with the developer. ). The developing roller 121 arranged on the downstream side of the photosensitive drum is in contact with the photosensitive drum 101 at a predetermined development gap with respect to the photosensitive drum 101, and the developing roller arranged on the upstream side of the photosensitive drum. Also in 111, the developer is in contact with the photosensitive drum 101. The state of the drive system at this time is shown in FIG.

  In FIG. 22B, the developing unit 150 has a photosensitive member in a movable direction in which the developing unit 150 is supported by the support unit 156 so as to be movable toward and away from the photosensitive drum, as compared with the state of FIG. It moves in the direction approaching the drum 101. Therefore, the gear 500G fixed to the drive shaft 500S coupled to the drive source provided on the image forming apparatus main body side and the idler gear 115G supported rotatably with respect to the rotation support means 155 of the developing unit 150 are provided. The state is shifted from the meshing position in the driving state. Here, in the engaged state, the rotation center of the drive shaft 500S and the gear 500G is set in the direction of approaching and separating the photosensitive drum by the support unit 156 with respect to the rotation support unit 155 and the rotation center of the idler gear 115G. Whereas the developing unit 150 moves in a direction close to the photosensitive drum 101 while being positioned at a right angle to the movable direction that is movably supported, the rotation axis of the drive shaft 500S and the gear 500G, Since the distance between the rotation support means 155 and the center of rotation of the idler gear 115G is an increasing direction, the gear 500G is obstructed from moving in the direction in which the idler gear 115G and the developing unit 150 are close to the photosensitive drum 101. Stable operation is possible. Here, the positional conditions of the rotation center of the drive shaft 500S and the gear 500G and the rotation center of the rotation support means 155 and the idler gear 115G necessary for realizing this operation are not limited to this, and the drive shaft 500S and the gear This can be realized by setting 500G to a position that allows the idler gear 115G and the developing unit 150 to move in the direction close to the photosensitive drum 101 from the driving state.

  A state in which the developing roller 111 arranged on the upstream side of the photosensitive drum is switched to a state in which the cam member 104 is further rotated in the clockwise direction in order to switch the developer to a non-contact state with respect to the photosensitive drum 101 is illustrated in FIG. 19 (a), the developing roller 121 disposed on the downstream side of the photosensitive drum is in contact with the photosensitive drum 101 with a predetermined developing gap with respect to the photosensitive drum 101, and the photosensitive drum The developing roller 111 arranged on the upstream side of the drum is in a non-contact state with the developer on the photosensitive drum 101.

  The state of the drive system at this time is the same as that shown in FIG. 20A, the gear 500G and the idler gear 115G are meshed, and the rotation center of the drive shaft 500S and the gear 500G is the rotation support means 155 and the idler gear. With respect to the rotation center of 115G, the developing unit 150 is positioned in a direction perpendicular to the movable direction in which the supporting unit 156 is supported so as to be movable toward and away from the photosensitive drum.

  In the present embodiment, the developing unit 150 that rotatably supports the two developing rollers 111 and 121 is effectively used so that the developing unit 150 can move in the approaching / separating direction with respect to the photosensitive drum 101. The cam member 104 is formed so that the timing at which the photosensitive member load fluctuation accompanying the completion of switching from the non-development state to the developing state and the photosensitive member load fluctuation accompanying the start of switching from the developing state to the non-developing state are close to each other. Thus, when an image is formed (transferred) from the photosensitive drum 101 onto the intermediate transfer belt 105, an area where an image cannot be formed on the intermediate transfer belt 105 can be reduced, and the size of the apparatus can be reduced by downsizing the intermediate transfer belt 105. And cost reduction, and the high rigidity of the intermediate transfer belt 105 can prevent elongation, vibration, etc., and improve the output image quality. It can be current.

  Also, here, at the same time when the development roller for performing development is switched from the non-development state to the development state, the development roller of the developing roller is started to switch from the development state to the non-development state. By forming the cam member 104 so that the photosensitive member load fluctuation accompanying the completion of the switching from the developing state to the developing state and the photosensitive member load fluctuation accompanying the start of switching from the developing state to the non-developing state occur at the same time. The area in which an image cannot be formed on the belt is minimized, and the intermediate transfer belt 105 can be greatly reduced in size and cost can be greatly reduced. Further, the intermediate transfer belt 105 can be further increased in rigidity and stretched. In addition, vibration and the like can be prevented more reliably, and the output image can be greatly improved in image quality.

  In particular, when the developing roller is brought into contact with the photosensitive drum during the developing operation as in the one-component developing method, the developing color switching operation from the non-developing state where the developing roller comes into contact with the photosensitive drum to the developing state is completed. The effect of this configuration is great because the influence of both the instant of time and the instant of starting the development color switching operation from the development state in which the developing roller is separated from the photosensitive drum to the non-development state is large.

1 is a schematic configuration diagram of an essential part of an image forming apparatus showing an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of the present invention, and is an explanatory diagram of a configuration / operation of an image forming unit. FIG. 10 is a diagram illustrating another embodiment of the present invention, and is an explanatory diagram of a configuration / operation of an image forming unit. FIG. 10 is a diagram illustrating another embodiment of the present invention, and is an explanatory diagram of a configuration / operation of an image forming unit. FIG. 10 is a diagram illustrating another embodiment of the present invention, and is an explanatory diagram of a configuration / operation of an image forming unit. FIG. 10 is a diagram illustrating another embodiment of the present invention, and is an explanatory diagram of a configuration / operation of an image forming unit. FIG. 5 is a diagram showing another embodiment of the present invention, and is a schematic perspective view of a main part showing a developing roller driving state in the developing state of FIG. FIG. 10 is a diagram showing another embodiment of the present invention, and is a schematic perspective view of a main part showing a developing roller driving state in the developing state of FIG. It is a schematic principal part perspective view which shows an example of the structure which implement | achieves the function of the driving force transmission means shown in FIG. 7, FIG. FIG. 9 is a schematic perspective view of a main part showing another example of a configuration for realizing the function of the driving force transmission means shown in FIGS. 7 and 8. FIG. 5 is a diagram showing another embodiment of the present invention, and is a schematic perspective view of a main part showing a developing roller driving state in the developing state of FIG. FIG. 10 is a diagram showing another embodiment of the present invention, and is a schematic perspective view of a main part showing a developing roller driving state in the developing state of FIG. It is a schematic principal part perspective view which shows an example of the structure which implement | achieves the function of the driving force transmission means shown in FIG. 11, FIG. It is a figure which shows the state which rotated the cam member in order to switch a developing function with the structure of FIG. FIG. 10 is a diagram illustrating another embodiment of the present invention, and is an explanatory diagram of a configuration / operation of an image forming unit. FIG. 10 is a diagram illustrating another embodiment of the present invention, and is an explanatory diagram of a configuration / operation of an image forming unit. FIG. 10 is a diagram illustrating another embodiment of the present invention, and is an explanatory diagram of a configuration / operation of an image forming unit. FIG. 10 is a diagram illustrating another embodiment of the present invention, and is an explanatory diagram of a configuration / operation of an image forming unit. FIG. 10 is a diagram illustrating another embodiment of the present invention, and is an explanatory diagram of a configuration / operation of an image forming unit. It is explanatory drawing of a structure and operation | movement of the drive system of the image forming unit shown in FIG. FIG. 10 is a diagram illustrating another embodiment of the present invention, and is an explanatory diagram of a configuration / operation of an image forming unit. It is explanatory drawing of a structure and operation | movement of the drive system of the image forming unit shown in FIG.

Explanation of symbols

101, 201: Photosensitive drum (image carrier)
102, 202: Charger 103, 203: Exposure device 104: Cam member 104a: Cam surface 105: Intermediate transfer belt (intermediate transfer member)
106: Secondary transfer member 110: Cyan developing device (C color unit)
111: Cyan developing roller (developing means)
112, 113: Cyan conveying screw (developer stirring and conveying means)
114, 124, 214, 224: Development switching mechanism 116, 126: Roller member 120: Magenta developer (M color unit)
121: Magenta developing roller (developing means)
122, 123: Magenta conveying screw (developer stirring and conveying means)
150: Development unit (holding means)
155: Supporting means 156: Supporting means 157: Energizing means 210: Yellow developing unit (Y color unit)
211: Yellow developing roller (developing means)
212, 213: Yellow conveying screw (developer stirring and conveying means)
220: Black developer (Bk color unit)
221: Black developing roller (developing means)
222, 223: Black conveying screw (developer stirring and conveying means)

Claims (16)

A developing unit that visualizes a latent image of the same rotating image carrier in an arbitrary color and another developing unit that visualizes the latent image in a color different from the arbitrary color, respectively. An image forming unit having a configuration facing the outer periphery of the image forming unit and adjacent to the outer periphery of the image forming unit, and when switching colors, from one of the two developing units during rotation of the image carrier. In the image forming unit for switching the developing function to the other developing means,
A holding unit that holds the one developing unit and the other developing unit so as to be rotatable about an axis parallel to the rotation axis of the image carrier, and supports the two developing units so as to be idled at both ends on the rotation axis. A roller member, and a cam member having a rotation shaft parallel to the rotation shaft at both ends in the rotation shaft direction of the image carrier,
The cam member rotates while being in contact with the roller member supported by the two developing means, so that the distance between the one developing means and the image carrier is in the developing state and the other developing means is The distance between the image carrier is in a non-development state, or the gap between the other development means and the image carrier is in a development state, and the gap between the one development means and the image carrier is in a non-development state. A cam surface for changing the distance between each developing means and the image carrier at any one position;
The holding means is supported to the image carrier so as to be rotatable about a rotation axis parallel to the rotation axis of the image carrier, and is supported to be movable toward and away from the image carrier. And a urging means for urging the holding means in one of the moving directions with respect to the image carrier, and a roller member supported by the two developing means by the urging force of the urging means. An image forming unit, which is always brought into contact with the cam surface. A developing unit that visualizes a latent image of the same rotating image carrier in an arbitrary color and another developing unit that visualizes the latent image in a color different from the arbitrary color, respectively. An image forming unit having a configuration facing the outer periphery of the image forming unit and adjacent to the outer periphery of the image forming unit, and when switching colors, from one of the two developing units during rotation of the image carrier. In the image forming unit for switching the developing function to the other developing means,
A holding unit that holds the one developing unit and the other developing unit so as to be rotatable about an axis parallel to the rotation axis of the image carrier, and supports the two developing units so as to be idled at both ends on the rotation axis. A roller member, and a cam member having a rotation shaft parallel to the rotation shaft at both ends in the rotation shaft direction of the image carrier,
The cam member rotates while being in contact with the roller member supported by the two developing means, so that the distance between the one developing means and the image carrier is in the developing state and the other developing means is The distance between the image carrier is in a non-development state, or the gap between the other development means and the image carrier is in a development state, and the gap between the one development means and the image carrier is in a non-development state. A cam surface for changing the distance between each developing means and the image carrier at any one position;
The holding means is supported to the image carrier so as to be rotatable about a rotation axis parallel to the rotation axis of the image carrier, and is supported to be movable toward and away from the image carrier. And a urging means for urging the holding means in one of the moving directions with respect to the image carrier, and a roller member supported by the two developing means by the urging force of the urging means. While always contacting the cam surface,
A driving unit that rotates and drives each developing unit, and a driving force transmitting unit that is rotatable coaxially with a rotation shaft that supports the holding unit are provided, and is driven from a developing unit driving source provided in the main body of the image forming apparatus. An image forming unit that transmits a force to a driving unit provided in the developing unit and the developing unit via a driving force transmitting unit on a rotation shaft of the holding unit. The image forming unit according to claim 1.
The cam members provided at both ends of the image bearing member in the rotational axis direction are such that the distance between the one developing device and the image bearing member is in a developing state by the rotation of the cam member, and the other developing device. And the position where the distance between the image carrier is in a non-development state, the distance between the one development means and the image carrier is in a non-development state, and the distance between the other development means and the image carrier is a development state And a position where the distance between the one developing means and the image carrier is in a non-development state and the distance between the other developing means and the image carrier is in a non-development state. An image forming unit. The image forming unit according to claim 1.
The cam members provided at both ends of the image bearing member in the rotational axis direction are such that the distance between the one developing device and the image bearing member is in a developing state by the rotation of the cam member, and the other developing device. And the position where the distance between the image carrier is in a non-development state, the distance between the one development means and the image carrier is in a non-development state, and the distance between the other development means and the image carrier is a development state A distance between the one developing means and the image carrier is in a developing state, and a distance between the other developing means and the image carrier is in a developing state. Image forming unit. The image forming unit according to claim 4.
The cam members provided at both ends of the image bearing member in the rotational axis direction are such that the distance between the one developing device and the image bearing member is in a developing state by the rotation of the cam member, and the other developing device. And the end of the movement from the position where the image carrier is in the non-development state to the position where the image carrier is in the development state. An image forming unit, characterized in that a cam surface is formed so as to start movement to a position. The image forming unit according to claim 1.
The image forming unit, wherein the cam member is provided coaxially with respect to a rotation axis of the image carrier. The image forming unit according to claim 1.
When a driven member is fixed on the same axis of a rotating shaft with respect to the one developing unit and the other developing unit, and the interval between the developing unit and the image carrier is in a developing state by rotation of the cam member, Driving force is transmitted to the driven member of the developing means and the driving force is not transmitted to the driven member of the developing means when the distance between the developing means and the image carrier is not developed. When a driving force member is provided and the driven member of the developing unit is driven in the driving force transmission state, the driving force acting on the driven member is a force in a direction in which the roller member abuts the cam surface. An image forming unit comprising the driving force transmitting means at a position having The image forming unit according to claim 1.
A driving means for rotationally driving the one developing means and the other developing means is provided, and the rotational driving force of the driving means is connected to each of the rotating shafts of the developing means and the rotating shafts of the driving means. In addition to transmitting to the developing means, the one developing means and the other developing means are positioned relative to the driving means so that the distance between the developing means and the image carrier is in the developing state by the rotation of the cam member. An image forming unit, characterized in that the developing means is provided with a driving force transmitting means capable of moving between positions where the interval between the image carriers is in a non-development state. The image forming unit according to claim 1.
A driving means for rotationally driving the one developing means and the other developing means is provided, and the rotational driving force of the driving means is connected to each of the rotating shafts of the developing means and the rotating shafts of the driving means. A driving force transmitting means for transmitting to the developing means is provided, and the driving force transmitting means releases the driving force transmitting state by moving the rotating shaft of the developing means and the rotating shaft of the driving means by a predetermined distance in the rotating shaft direction. And a driving force transmitting portion in which the rotating shaft of the developing means is movable between a position where the developing member is in a developing state and a position where the developing member is in a non-developing state by rotation of the cam member. And at least one of the cam members provided at both ends in the rotation axis direction of the image carrier, the spacing between the one developing means and the image carrier is in a developed state by the rotation thereof, and Other The developing means and the image carrier are in a non-developing state, the driving force transmitting means connected to the rotating shaft of the one developing means and the rotating shaft of the driving means is in a driving force transmitting state, and The position where the driving force transmitting means connected to the rotating shaft of the other developing means and the rotating shaft of the driving means is in the driving force transmission release state, and the distance between the other developing means and the image carrier is in the developing state. And the distance between the one developing means and the image carrier is in a non-developing state, and the driving force transmitting means connected to the rotating shaft of the other developing means and the rotating shaft of the driving means transmits the driving force. The rotating shafts of the developing means and the driving means are in positions where the driving force transmitting means connected to the rotating shaft of the one developing means and the rotating shaft of the driving means are in a driving force transmission release state. The image forming unit cam surface to change the rotation axis direction between the rotation axis, characterized in that it is formed integrally. The image forming unit according to claim 2.
The driving force transmitted from the developing means driving source to the driving force transmitting means on the rotating shaft of the holding means is a component in the direction in which the holding means is movably supported, and the holding means is used as the image carrier. An image forming unit characterized in that the image forming unit is in a direction in which the image forming unit approaches the image forming unit. The image forming unit according to claim 2.
The developing means driving source is a rotational driving means capable of forward and reverse rotation, and a one-way clutch is provided in each of the driving force transmission systems between the developing means driving source and the two developing means. At the time of rotation, the one-way clutch provided in the driving force transmission system to one developing unit is locked, and the driving force is transmitted to the one developing unit and also provided to the driving force transmission system of the other developing unit. The image forming unit, wherein the one-way clutch is idled and no driving force is transmitted to the other developing means. The image forming unit according to claim 11.
During the forward rotation of the developing means driving source, the one-way clutch provided in the driving force transmission system to one developing means is locked, and the driving force is transmitted to the one developing means and the developer stirring and conveying means. An image forming unit, wherein the one-way clutch provided in the driving force transmission system of the other developing means is idled, and no driving force is transmitted to the other developing means and the developer agitating / conveying means. The image forming unit according to claim 2.
The cam members provided at both ends of the image bearing member in the rotational axis direction are such that the distance between the one developing device and the image bearing member is in a developing state by the rotation of the cam member, and the other developing device. And the position where the distance between the image carrier is in a non-development state, the distance between the one development means and the image carrier is in a non-development state, and the distance between the other development means and the image carrier is a development state A position where the distance between the one developing means and the image carrier is in a non-development state and a position where the distance between the other developing means and the image carrier is in a non-development state. The driving force transmitting means for transmitting the driving force from the developing means driving source to the driving force transmitting means on the rotating shaft of the holding means is a driving force transmitting state with the driving force transmitting means on the rotating shaft of the holding means. To the image carrier. The image forming unit, characterized in that provided in an acceptable position to move in a direction to separate against. The image forming unit according to claim 2.
The cam members provided at both ends of the image bearing member in the rotational axis direction are such that the distance between the one developing device and the image bearing member is in a developing state by the rotation of the cam member, and the other developing device. And the position where the distance between the image carrier is in a non-development state, the distance between the one development means and the image carrier is in a non-development state, and the distance between the other development means and the image carrier is a development state And a position where the distance between the one developing means and the image carrier is in the developing state and the distance between the other developing means and the image carrier is in the developing state. The driving force transmitting means for transmitting the driving force from the driving source to the driving force transmitting means on the rotating shaft of the holding means is the driving force transmitting state with the driving force transmitting means on the rotating shaft of the holding means. The holding means is close to the image carrier The image forming unit, characterized in that provided in an acceptable position to move in a direction for moving. A developing unit that visualizes a latent image of the same rotating image carrier in an arbitrary color and another developing unit that visualizes the latent image in a color different from the arbitrary color, respectively. One of the two developing means during rotation of the image carrier when the color is changed in the image forming unit. The developing function is switched from one developing means to the other developing means, and the visible image on the image carrier obtained by making the visible image is sequentially transferred to the intermediate transfer member, and the transfer image on the intermediate transfer member is transferred to the intermediate transfer member. Furthermore, in an image forming apparatus that obtains a recorded image by transferring to a recording material,
An image forming apparatus comprising the image forming unit according to claim 1 as the image forming unit. The image forming apparatus according to claim 15.
An image forming apparatus comprising a plurality of the image forming units arranged along the intermediate transfer member.

Images