JP4117090B2 - Color image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
According to the present invention, a developing unit having a plurality of developing units disposed around a rotation axis is rotated around the rotation axis, and an arbitrary developing unit is moved to a developing position facing a latent image carrier. The present invention relates to a color image forming apparatus provided with a rotary developing device that performs development.
[0002]
[Prior art]
Conventionally, in a color image forming apparatus having the above revolver developing unit, it is known that a bias is applied by a power supply circuit to the developing roller in the developing unit brought to the developing position by the rotation of the developing unit. Japanese Patent Application Laid-Open No. 7-325480 discloses a color which does not generate an excessive load for the rotation of the revolver developing unit, and can reliably apply a developing bias to the developing roller in the revolver developing unit unit from the main body side. An image forming apparatus is disclosed.
[0003]
In this image forming apparatus, a rod-shaped terminal provided on the main body abuts against the shaft of the developing roller that has arrived at the developing position facing the latent image carrier by the rotation of the developing unit, and a bias is applied. The rod-shaped terminal can be advanced and retracted in a direction in which it is in contact with and away from the roller shaft, and is urged in a direction in which it comes into contact with the shaft. For this reason, a developing bias can be reliably applied to a developing device for developing without generating an excessive load.
[0004]
[Problems to be solved by the invention]
However, in the above-described image forming apparatus, the developing roller shaft of each developing device, which is the other terminal, comes into contact with a certain position of the rod-shaped terminal, so that the wear of the rod-shaped terminal progresses and the replacement is forced in a relatively short time. There was a problem.
[0005]
The present invention eliminates the above-mentioned conventional problems, enables a reliable voltage application without excessive increase in the driving load of the revolver developer unit, and delays the wear of the terminals, thereby extending the service life. An object of the present invention is to provide a color image forming apparatus.
[0006]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention provides a plurality of components arranged around the rotation axis.DeveloperRotating type developing device that rotates around the rotation axis and moves an arbitrary developing device to a developing position facing the latent image carrier to perform development.A power receiving terminal provided at the end of the developing unit in the direction of the rotation axis, and a power supply terminal provided on the image forming apparatus main body and capable of contacting the power receiving terminal of the developing unit that has arrived at the developing position. And a terminal support means for supporting the power supply terminal so as to be able to advance and retreat in a direction in contact with the power receiving terminal, and supporting the power supply terminal in a state of being biased in a direction in contact with the power receiving terminal, In the color image forming apparatus, the power supply terminal is formed in a cylindrical shape, and the axis thereof is disposed outside the locus of the power receiving terminal by rotation of the rotary developing device. A drive mechanism of a drive mechanism using a gear that rotates the terminal around an axis is provided, and the drive means includes a gear that rotates the power supply terminal and the number of teeth of the gear that inputs a driving force to the gear. We propose a color image forming apparatus, characterized in that in the prime relationship.
[0007]
  In the present invention,The gear that inputs driving force to the gear that rotates the power supply terminal is the revolver input gear of the rotary developing device.And effective.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a color electrophotographic printer (hereinafter referred to as a printer) which is a color image forming apparatus will be described.
[0010]
FIG. 1 is a schematic configuration diagram of a printer according to this embodiment. First, an outline of the entire printer will be described.
In FIG. 1, a photosensitive drum 1 as a latent image carrier is uniformly charged by a charging charger 2 as a charging means while being driven to rotate in the direction of arrow A, and then based on image information by a laser optical device 3. An electrostatic latent image is formed on the surface by scanning exposure. Here, the image information to be exposed is single-color image information obtained by separating a desired full-color image into yellow, magenta, cyan, and black color information. The electrostatic latent image formed on the photosensitive drum 1 is developed with yellow, magenta, cyan, and black toners as predetermined developers by a rotary type developing device 4 described later, whereby the photosensitive drum 1 is developed. Each color image is sequentially formed on top.
[0011]
Each color image formed on the photosensitive drum 1 is printed on the intermediate transfer belt 5 that rotates in the direction of arrow B in the drawing in synchronization with the photosensitive drum 1 for each of monochrome colors of yellow, magenta, cyan, and black. The next transfer charger 6 sequentially superimposes and transfers. The yellow, magenta, cyan, and black images superimposed on the intermediate transfer belt 5 are transferred from the double-sided copying / automatic sheet feeding cassette 7 or the manual sheet feeding tray 7a through the sheet feeding rollers 8 and 8a and the registration roller 9. Are collectively transferred by the secondary transfer charger 11 onto the transfer paper 10 conveyed to the front. After the transfer, the transfer paper 10 is fixed with a toner image by a fixing device 12 and discharged out of the apparatus as a full color print.
[0012]
The toner on the photoconductive drum 1 that has not been transferred onto the intermediate transfer belt 5 is removed from the photoconductive drum 1 by the photoconductor cleaner 13, and the toner on the intermediate transfer belt 5 that has not been transferred onto the transfer paper 10. The toner is removed from the intermediate transfer belt 5 by the intermediate transfer belt cleaner 14.
[0013]
Next, the rotary developing device of the present embodiment will be described. 2 is an exploded perspective view of the developing device, FIG. 3 is a cross-sectional view showing an internal structure of the developing unit 40 of the developing device, and FIG. 4 is an explanatory diagram of a communication structure between the developing unit 40 and the toner container unit 45. 5 is a perspective view from the front showing the drive system of the developing unit 40 and the like.
[0014]
Referring to FIG. 2, the rotary developing device includes, for example, black, cyan, yellow, and magenta developing devices, and the outer periphery of the printer is rotatably mounted around the central axis in the printer body. Developer unit 40 and four developer containers 41, 42, 43, 44 corresponding to the respective developer units one by one and containing toners of black, yellow, magenta, and cyan, respectively, and the developer unit 40, a toner container unit 45 which is attached so as to be substantially coaxial on the front side in the direction of the central axis thereof, and rotates integrally with the developing unit 40 around the central axis, and the developer unit 40 and the toner container The unit 45 (hereinafter, referred to as a revolver developing unit) is slidable on the printer main body substantially parallel to the central axis while holding the unit 45. A pay table 46, and a cover 47 provided so as not to rotate in the housing base before the support plate 48 so as to cover the toner container unit 45.
[0015]
The revolver developing unit supports the disk-shaped front end wall 50 of the developing unit 40 with, for example, two supporting rollers 49 rotatably attached to the front supporting plate 48 of the accommodating table 46, and the developing unit 40 The central body 52 of the front end taper projecting from the center of the disc-shaped rear end wall 51 is rotatably supported by the central shaft insertion hole 54 formed in the rear side plate 53 of the main body. For example, as shown in FIG. 1, the rotation axis thereof is positioned at a position parallel to each other in the same horizontal plane as the rotation axis of the photosensitive drum 1, and is rotatable.
[0016]
First, the details of the mechanism for rotatably supporting the revolver developing unit will be described with reference to FIG. In FIG. 2, the storage platform 46 includes a front support plate 48, a rear support plate 55, a side cover 59 having front and rear ends fixed to both support plates and reinforced by connecting rods 56, 57, and 58. Have In the present embodiment, the side cover 59 is used for preventing the temperature rise of the developing unit 40. The front support plate 48 is formed with an insertion hole 60 into which the revolver developing unit can be inserted, and in addition to the support roller 49, a toner supply roller driving motor 61 provided in the toner container unit 45, and the motor 61 A gear train driven by a motor 61 is attached. An intermediate plate 63 is attached to the connecting rods 56 and 57 in the vicinity of the rear support plate 55. The intermediate plate 63 is provided with a positioning pin that fits into a positioning hole formed in the rear plate of the main body. ing. A proximal end portion of a bracket 64 holding a rotary positioning roller 66 is attached to a positioning pin portion between the intermediate plate 63 and the rear support plate 55 so as to be swingable. The bracket 64 is urged by a spring 67 in such a direction that the roller 66 is fitted into a recess 65 formed at a predetermined position on the peripheral surface of the developing unit rear end wall 51 (see also FIG. 5).
[0017]
The main body front side plate 68 is formed with an insertion hole 69 or the like into which the storage table 46 carrying the revolver developing unit can be inserted, and the storage table 46 is interposed between the main body front side plate 68 and the main body rear side plate 53. The upper and lower guides 70 and 71 are supported so as to be slidable. Guided portions 72 and 73 are provided at the upper end and the side of the side cover 59 of the receiving table as the receiving table portion guided by the guides 70 and 71, respectively. A guide pin groove 75 into which a guide pin 74 planted upward in the guide 71 enters is formed on the lower surface portion.
[0018]
In the support mechanism for the revolver developing unit described above, when the main body of the storage base 46 is inserted, the tapered tip end portion of the positioning pin protruding from the intermediate plate 63 has a main body rear side plate immediately before the storage base insertion into the printer main body is completed. 53 enters the positioning hole 53, and when the insertion is completed, the rear support plate 55 and the bracket 63 of the storage base 46 are accurately positioned in the main body. On the other hand, in the pulled-out state of the storage base 46, the rear end portion of the revolver developing unit supported by the rear plate 53 of the storage base 46 is centered on the central axis 52 having a tapered tip immediately before the main body insertion of the storage base 46 is completed. The shaft is lifted as it gradually enters the shaft insertion hole 54, and is completely lifted from the rear support plate 55 when the insertion is completed. The front support plate 48 of the storage base 46 is fixed to the main body front side plate 68 with screws 76 or the like after the insertion of the storage base 46 into the main body is completed. As a result, the revolver developing unit is supported at the front end portion by the support roller 49 of the front support plate 48 that is accurately positioned on the main body, and is pivotable to the main body rear side plate 53 via the center shaft 52. The part is positioned and can be rotated.
[0019]
A revolver driving gear 78 driven by a revolver rotating motor such as a stepping motor (not shown) is attached to the main body rear side plate 53 for revolver developing unit rotation driving. This meshes with the revolver input gear 79 having substantially the same diameter as the rear end plate 51 fixed to the rear surface of the rear end plate of the developing unit 40 by screws or the like, so that the revolver developing unit is rotated ( (See also FIG. 5). Further, a development drive gear 81 driven by a development drive motor (not shown) is also attached to the main body rear side plate 53 in order to drive a developing roller 84 and the like in the developing unit 40 described later (see also FIG. 5). ).
[0020]
Next, the developing unit 40 will be described with reference to FIGS. In FIG. 3, the developing unit 40 includes a partition wall provided between the above-described substantially disc-shaped front and rear end plates 50 and 51. The partition wall includes a hollow cylindrical portion 82 into which a cylindrical black toner bottle containing black toner can be inserted, and extends radially from the hollow cylindrical portion 82 so that the space around the hollow cylindrical portion 82 is substantially mutually circumferential. It comprises developing device casing parts 83, 83C, 83M and 83Y which are divided into four developing chambers of the same type. In each of these developing chambers, a two-component developer composed of a carrier as a developer and toner of each color is accommodated. In the example shown in the figure, the developing position of the black developing device containing black toner and carrier is at the developing position facing the photosensitive drum, and the yellow developing device containing yellow toner and carrier in the counterclockwise order in the figure. A developing chamber, a developing chamber of a magenta developing device containing magenta toner and a carrier, and a developing chamber of a cyan developing device containing cyan toner and a carrier.
[0021]
Here, since the internal structures of the four developing chambers are exactly the same, the internal structure will be described below with reference to the black developing chamber in the developing position in FIG. 3 as an example, and the internal structures of the other developing chambers correspond. As the reference numerals of the members, the same reference numerals with Y, M, and C suffixes are given in the drawing to distinguish the yellow, magenta, and cyan developing chambers from the same numerals as in the black developing chamber, and the description thereof is omitted.
[0022]
In the black developing device in the developing position in the figure, an opening toward the photosensitive drum 1 is formed in the developing device casing 83, and a developing roller 84 is provided in the developing chamber so that a part is exposed through the opening. Is provided. Further, a developing blade 84 which is carried on the developing roller 84 and regulates the amount of developer conveyed to the portion facing the photosensitive drum 1 in the developing chamber, and the developing which is restricted by the doctor blade 85 and is held in the developing chamber. An upper conveying screw 86 for conveying a part of the agent along the central axis direction from the rear to the front, a guide 87 thereof, and an agitation paddle 88 for agitating the developer in the developing chamber are provided. The stirring paddle 88 includes a hollow cylindrical portion 89 in which a plurality of developer discharge holes 89 a are formed across the width direction of the developing roller 84, and a plurality of stirring plate portions 90 extending radially from the peripheral surface of the hollow cylindrical portion 89. The hollow cylindrical portion 89 accommodates a lower conveying screw 91 that conveys the developer in the direction opposite to the upper conveying screw 86 along the central axis direction. The developer casing below the lower conveying screw 91 has a developer discharge port used as a deteriorated developer discharge port and an unused developer (toner mixed) input port when the developer is changed due to deterioration in the development chamber. An outlet 92 is formed. The discharge port 92 is covered from the outside by a cap 93 attached with a screw 94.
[0023]
In FIG. 4, the front end portions of the upper and lower transport screws 86 and 91 extend to the outside of the front end wall 50 of the developing unit, and the developer transported by the upper transport screw 86 to the extended portion is transported downward. A dropping part 96 for dropping the screw 91 by its own weight is provided on the screw 91. The developer regulated by the doctor blade 85 and conveyed to the front side by the guide 87 and the upper conveying screw 86 falls on the lower conveying screw 91 via the dropping portion 96, and the developing roller 84 is developed by the lower conveying screw 91. And then discharged into the developing chamber from the developer discharge port of the stirring paddle hollow cylindrical portion. Thereby, so-called lateral stirring of the developer in the developing chamber is performed. Further, the developer discharged from the developer discharge port of the hollow cylindrical portion 82 of the stirring paddle 88 to the developer reservoir in the lower portion of the developing chamber is stirred by the stirring plate portion by the rotation of the stirring paddle 88, whereby vertical stirring is performed. Done. Further, the front end portion of the lower conveying screw 91 extends further to the front side than the dropping portion 96, and each toner receiving case 91Y, M, C, 110 provided corresponding to each developing chamber of the toner container unit 45 is provided. It extends to the inside, specifically below the toner supply roller 97 provided in the case.
[0024]
In the example of FIG. 3, for example, as shown for the yellow developing device, the front and rear end walls that support the developing roller 84Y and the doctor blade 85Y are configured as a small end wall 104 that can be separated from other front and rear end walls. In addition, the cleaning of the developing chamber and the replacement of parts are facilitated.
[0025]
Next, the toner container unit 45 will be described with reference to FIG. 2 again. The toner container unit 45 includes a disk-shaped unit face plate 108 and a total of four toner receiving cases 91Y, M, C, 110 attached to the front face of the face plate so as to correspond to each developing device on a one-to-one basis. Have The unit face plate 108 is formed with a circular through hole (not shown) through which a cylindrical black toner container can be passed in the center thereof, and each of the toner receiving cases 91Y, 91M, 91C, 110 is It escapes from this through-hole and is attached.
[0026]
Of these four toner receiving cases 91Y, 91M, 110C, 110, the three color toner receiving cases 91Y, 91M, 91C corresponding to the respective color developing units have their corresponding developing chambers located at the developing position. A toner receiving port facing upward is formed. The color toner containers 42, 43, 44 having the same color and containing the color toner are mounted on the mounting portion around the toner receiving port with the toner discharge port facing downward in the revolver developing unit rotation axis direction. It is attached by a slide.
[0027]
On the other hand, the black toner receiving case 110 corresponding to the black developing device has substantially the same shape as the entire peripheral wall shape of the color toner receiving cases 91Y, 91, and C attached to the color toner receiving cases 42, 43, and 44. It has a peripheral wall shape. A toner receiving port having a shape corresponding to the toner discharge port of the black toner container 41 is formed at a portion facing the center line of the revolver developing unit in the peripheral wall portion having the same shape as the color toner receiving case.
[0028]
The black toner container 41 has a cylindrical shape, and a toner discharge port is formed in a peripheral wall portion at one end portion in the longitudinal direction, and a protrusion for feeding toner is formed on the inner peripheral surface portion from the other end portion to the toner discharge port. It is spirally formed on the side. The spiral ridges feed the stored toner from the rear end to the front end while the unit is rotating integrally with the revolver developing unit, and receive the black toner from the toner discharge port. The toner is supplied into the toner receiving port of the case. Such a black toner container 41 enters the hollow cylindrical portion 82 of the developing unit 40 through the central portion of the toner container insertion notch 47a formed in the cover 47 described above. For example, the toner container unit 45 is attached in a state where the front end part is substantially flush with the front surface of the front end wall part of each case.
[0029]
Then, as shown in FIG. 4 taking the black toner receiving case 110 as an example, a toner replenishing roller 97 is provided in each of the four toner receiving cases 91Y, 91M, C, 110. The toner replenishing roller 97 has a front end wall portion and a unit face plate of the case so as to be positioned almost directly above the portion where the lower conveying screw 91 extends into the case when the corresponding developing chamber is located at the developing position. 108 is pivotally supported. A shaft end portion of the toner replenishing roller 97 supported by the unit face plate 108 passes through the face plate 108 and protrudes toward the developing device unit 40, and a gear 197 is fixed to the protruding end portion. A drive input replenishment input gear (not shown) that meshes with the gear 197 is rotatably provided on the surface of the unit face plate 108 on the developing unit side. Of the replenishment input gears provided for each toner replenishment roller 97, the one corresponding to the toner replenishment roller 97 in the case corresponding to the developing device at the development position is a gear driven by the replenishment motor 61 described above. (See FIG. 2) and can be rotated by the motor 61. The toner dropped onto the lower conveying screw 91 by the rotation of the toner replenishing roller 97 is taken into the developer dropped from the upper conveying screw 86 halfway, and conveyed to the developing chamber by the lower conveying screw 91 while being mixed with each other. The toner density of the developer in the developing chamber is increased. Toner replenishment control is performed by drive control of the replenishment motor 61 that drives the toner replenishment roller 97.
[0030]
Next, a mechanism for rotationally driving a rotating body such as a developing roller in the developing unit 40 will be described with reference to FIG. The illustrated gears are provided on the rear end wall 51 of the developing unit 40, specifically on the rear side of the revolver input gear 79 fixed to the rear end wall 51. That is, the developing roller gear 98 is fixed to the shaft end portion of the developing roller 84 that penetrates the rear end wall 51 and the like and protrudes to the rear side of the revolver input gear 79. Upper and lower conveying screw gears 99 and 100 are fixedly provided at the shaft ends of the upper and lower conveying screws 86 and 91 protruding to the rear side. In the illustrated example, the idler gear 101 meshed with the developing roller 84 gear and the lower conveying screw gear 100 and the development output gear 81 attached to the main body rear side plate 53 and driven by the development driving motor 80 are meshed. A developing input gear 95 is attached to the back side of the rear end wall 51 of the developing unit. These gears are developed on the main body side as shown in FIG. 5 when the revolver developing unit provided on the rear end wall side is carried on the storage base 46 and inserted into the printer main body as described above. The output gear 81 meshes with the development input gear 95 on the revolver development unit side. At the same time, as shown in FIG. 5A, the revolver input gear 79 on the revolver developing unit side meshes with the revolver output gear 78 on the main body side.
[0031]
In FIG. 5 in which the above meshing has been realized, during development, the development output gear 81 is driven in the direction indicated by the arrow A in the figure, and the upper and lower conveying screw gears 99 and 100 are rotated via the development input gear 95 meshed therewith. Then, the upper and lower conveying screws are driven to rotate. Further, the developing roller gear 98 is rotated through the developing input gear 95, the lower conveying screw gear 100, and the idle gear 101, so that the developing roller 84 is rotationally driven.
[0032]
When the developing device to be used is switched, the revolver output gear 79 driven by the revolver driving motor is rotated in the direction of arrow B shown in FIG. 5 to rotate the revolver developing unit in the direction of arrow C. The developing device is switched to the developing position, and the positioning roller 66 is inserted into the recess 65 formed at a predetermined position on the peripheral surface portion of the rear end wall 51 of the revolver developing unit to position the revolver developing unit. To do. If the development drive gear 81 is rotated in the direction of arrow A after this positioning, a rotational moment indicated by arrow D in the figure acts on the revolver development unit. Therefore, the shape of the recess 65 and the force of the spring 67 that biases the rotation positioning roller 66 are set so that the revolver developing unit can be positioned against this rotation moment.
[0033]
Here, in the present embodiment, a development bias can be applied to each developing roller in the revolver developing unit from the main body side without fail, without causing an excessive load for the rotation of the revolver developing unit. The configuration will be described in detail with reference to FIG.
[0034]
In FIG. 6, a terminal 106 serving as a power supply terminal for applying a developing bias connected to a bias circuit 105 is held at a fixed position of the main body rear side plate 53 facing the end of the developing roller shaft 98a of the developing unit located at the developing position. A bracket 107 is attached. In this case, the terminal 106 is formed in a cylindrical shape, and the tip end 106a facing the end of the developing roller shaft 98a serving as a power receiving terminal has a rounded corner. Further, the rear end of the terminal 106 is provided with a flange portion 106b, and the flange portion 106b is movable in the direction of arrow E along a guide hole 107b formed in the bracket 107 and is rotatably mounted. With this configuration, the terminal 106 can slide in the direction of arrow E along the guide hole 107b and can rotate around the axis.
[0035]
A spring 107a made of a conductive material that constantly biases the terminal 106 in a direction to contact the end of the developing roller shaft 98a is inserted into the guide hole 107b, and the terminal 106 is connected to its flange by the elastic force of the spring 107a. The portion 106b is held at a position in pressure contact with the end portion of the guide hole 107b (lower end in FIG. 6). The terminal 106 at this position is set so as to surely contact the end of the developing roller shaft 98a of the developing unit located at the developing position which is the other terminal. Then, the terminal 106 and the end of the developing roller shaft 98a of the developing unit positioned at the developing position are surely in contact with each other, so that the bias circuit 105 is connected to the lead wire 105a and the bracket 107, the relay terminal 107c fixed to the bracket 107, the spring 107a, and the terminal 106. Then, a bias is applied to the developing roller shaft 98a. The end of the developing roller shaft 98a is rounded so as to be substantially hemispherical so that the terminal 106 can be smoothly abutted. The axis of the terminal 106 is arranged outside the locus of the developing roller shaft 98a due to the rotation of the revolver developing unit. With this configuration, the abrasion that occurs in the terminal 106 due to repeated contact between the terminal 106 and the developing roller shaft 98a deviates from the center of the terminal 106 and approaches the center of the revolver developing unit.
[0036]
In the developing device configured as described above, since the terminal 106 can rotate around the axis, when the revolver developing unit is rotated, the end of the developing roller shaft 98a is urged by the contact / separation to slightly increase the rotational force. Rotate. By this rotation, the position where the end of the developing roller shaft 98a contacts the terminal 106 is not fixed, and it is possible to prevent a part of the terminal 106 from being concentrated and worn.
[0037]
By the way, in the above embodiment, since the terminal 106 is rotated by the end of the developing roller shaft 98a, the terminal 106 does not rotate when a load is applied to the terminal 106 for some reason, and the amount of rotation cannot be controlled. There is a risk of doing.
[0038]
Therefore, in the embodiment shown in FIG. 7, the terminal 106 is configured to be driven by a driving device. Specifically, as shown in FIG. 7, a gear 109 is attached in the intermediate region of the terminal 106, and the gear 109 and the terminal 106 can freely move with respect to each other in the axial direction, but the rotation around the axis is possible. On the other hand, it is restrained and mounted so as to rotate together. This method can be easily implemented by forming a groove extending in the axial direction in one of the gear 109 and the terminal 106 and providing a protrusion on the other side along the groove.
[0039]
With this configuration, when the developing roller shaft 98a and the terminal 106 come into contact with each other, the terminal 106 is retracted. On the other hand, the gear 109 does not become a resistance. Rotate. Note that the gear 109 of this example meshes with the revolver input gear 79, and therefore the terminal 106 can be rotated by the rotation of the revolver. At this time, by making the relationship between the number of teeth of the revolver input gear 79 and the number of teeth of the gear 109 a prime number, the stop position of the terminal 106 becomes a different position each time the revolver input gear 79 rotates and stops.
[0040]
With this configuration, the position where the developing roller shaft 98a and the terminal 106 come into contact with each other during development can be set to a different position every time. As a result, the wear of the terminal 106 is not biased to one place, and the whole is worn on the average, and the life of the terminal 106 can be greatly extended.
[0041]
As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to the said embodiment, Various modifications can be made.
For example, in the above-described embodiment, the developing roller shaft 98a is a power receiving terminal, but the power receiving terminal may be provided separately from the developing roller shaft 98a. At this time, in the above-described embodiment, the terminal 106 is configured to be movable in the retracting direction at the time of contact, but the power receiving terminal may be slidable in the retracting direction. However, if the power receiving terminal can be slid in the retracting direction, it is necessary to provide the same number of mechanisms as the number of developing units, and it is inevitable that the above-described embodiment is disadvantageous in terms of cost.
[0042]
【The invention's effect】
  The present inventionAccording to the configuration ofThe wear of the power supply terminal can be made uniform all around, and the life of the power supply terminal can be greatly extended.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram showing the overall structure of a color image forming apparatus according to the present invention.
FIG. 2 is an exploded perspective view of a rotary developing device in the color image forming apparatus.
FIG. 3 is a cross-sectional view of a developing unit of the rotary developing device.
4 is an explanatory side view of the developing unit driving section shown in FIG. 3; FIG.
FIG. 5 is an explanatory diagram showing a connection structure between a developing device and a toner container in the rotary developing device.
FIG. 6 is an explanatory cross-sectional view showing an example of applying a developing bias.
FIG. 7 is an explanatory cross-sectional view showing another example of applying a developing bias.
[Explanation of symbols]
1 Photosensitive drum
4 Rotating type developing device
40 Development unit
98a Developing roller shaft
105 Bias circuit
106 terminals
107 Bracket
107a spring

Claims (2)

A rotary developing device that performs development by rotating a plurality of developing units disposed around a rotation axis about the rotation axis and moving any developing unit to a development position facing a latent image carrier. A power receiving terminal provided at an end of the developing unit in the direction of the rotation axis, and a power supply terminal provided on the image forming apparatus main body side and capable of contacting the power receiving terminal of the developing unit that has arrived at the developing position And a terminal support means for supporting the power supply terminal so as to be able to advance and retreat in the direction of contact with the power receiving terminal, and for supporting the power supply terminal in a state of being biased in the direction of contacting the power receiving terminal. In the color image forming apparatus, the power supply terminal is formed in a cylindrical shape, and the axis thereof is located outside the locus of the power receiving terminal by the rotation of the rotary developing device.
Drive means of a drive mechanism by a gear that rotates the power supply terminal around an axis is provided, and the drive means has a prime number of teeth of a gear that rotates the power supply terminal and a gear that inputs driving force to the gear. A color image forming apparatus characterized by having a relationship. 2. The color image forming apparatus according to claim 1, wherein a gear for inputting a driving force to a gear rotating the power supply terminal is a revolver input gear of a rotary developing device.

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