JPH07117784B2 - Rotary developing device for image forming apparatus - Google Patents

Description

TECHNICAL FIELD The present invention relates to a developing unit having a plurality of developing devices and rotatably supported, and a predetermined developing position in which each developing device of the unit faces a latent image carrier. The present invention relates to a rotary developing device of an image forming apparatus having stop means for stopping the image forming apparatus.

2. Description of the Related Art In a rotary developing device of the above type used in an image forming apparatus such as a copying machine or a printer, each developing device having a function of visualizing a latent image with a developer is designed to perform a predetermined development around a latent image carrier. The electrostatic latent image is visualized by being selectively rotated to a position and positioned. For the purpose of this positioning, the above-mentioned stop means is used, but the conventional stop means is composed of a plurality of recessed grooves formed in the developing unit and a locking member that engages with the recessed groove. The developing unit is positioned and stopped by being engaged with the groove by a biasing means such as a spring. When the developing unit is rotated from this engaged state, it becomes difficult for the locking member to come off due to the frictional force with the concave groove and the spring force, which may impede the smooth rotation of the developing unit. For this reason, the conventional stop means is configured to remove the locking member from the groove by pulling the locking member with a solenoid.

However, if the solenoid is provided, not only the cost of the apparatus becomes higher, but also if the operation start timing of the solenoid and the rotation start timing of the developing unit are not correctly aligned, the smooth rotation of the developing unit cannot be expected, so that both The means for adjusting the operation start timing was required, and the configuration of the device was inevitably complicated.

OBJECT The object of the present invention is to provide a developing apparatus of the type described at the outset in which the above-mentioned conventional drawbacks are eliminated by a simple construction.

To achieve the above object, the present invention provides a rotary developing device of the type described at the beginning, in which the stop means is arranged around the rotation center of the developing unit and is formed on the developing unit itself. And a locking member that is in contact with the cam surface and is supported by a portion other than the developing unit, and the locking member is attached to the cam surface so that the locking member is constantly in pressure contact with the cam surface. A urging means for urging the cam surface, and a concave groove is formed on the cam surface, into which the locking member is pressed while being pressed in order to position and stop the developing device at a predetermined developing position. From the time when the cam surface rotates due to the rotation of the developing unit and the locking member starts to engage with the concave groove to the bottom of the concave groove, the inclined surface of the concave groove with which the locking member abuts is 1 inclined surface, cam surface is development unit When the inclined surface of the concave groove which is rotated by the rotation of the engaging member engaging with the bottom of the groove until the engaging member abuts the concave groove from the bottom of the groove is the second inclined surface. , The second inclined surface is proposed to be formed with a gentler gradient than the first inclined surface.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a rotary developing device of a copying machine, which is an example of a developing and forming device, and this developing device has a developing unit supported by a copying machine main body 2. The developing unit 1 includes a plurality of developing units 3, 3R, 3B, which are integrally incorporated in the illustrated example.
have. The developer chambers 4, 4R, 4B of the developing units 3, 3R, 3B are provided with three casing members 5 made of a non-magnetic material such as aluminum.
It is partitioned by one partition wall 6, 6R, 6B and two end walls 7, 8 fixed to both ends thereof (see FIGS. 3 and 4).

Each developer chamber 4, 4R, 4B has different color developer 9, 9R, 9B
And each of these developers is black, red, and blue in this example. In each developer chamber, cyan,
It is possible to store the developers of yellow and magenta toners to form a full-color image, or to store the developers of the same color in each developer chamber and selectively use them. It can also be configured. Although a one-component developer containing no carrier can be used as the developer, a two-component developer containing a carrier and a toner, at least a part of which is a magnetic material, is used in the example of the figure. Is used.

Although the first to third developing units 3, 3R, 3B are arranged radially around the rotation center O of the developing unit 1, since the structures are all the same, in the following description, mainly the first Clarifying the configuration of the developing device 3 of the other, other developing devices 3R, 3B
With respect to each of the parts, the reference numerals assigned to the respective elements of the first developing device 3 are denoted by R and B, and the duplicate description thereof will be omitted.

The developing unit 1 is rotatably supported around its rotation center O, and each developing device (more accurately, a developing roller described later) rotates to a predetermined developing position to perform a developing operation.
FIG. 1 shows a state in which the first developing device 3 occupies the developing position.

In FIG. 1, the developing roller 10 provided in the first developing device 3 is partially exposed from the opening formed by the two partition walls 6 and 6R (see also FIG. 3). The latent image carrier rotatably supported by the copying machine main body 2, in this example, occupies a predetermined developing position with respect to the photosensitive drum 11. It is well known that a latent image carrier composed of a photoconductor belt may be used instead of the photoconductor drum, and a latent image carrier composed of a dielectric belt or a dielectric drum is used depending on the model of the image forming apparatus. Is.

The developing roller 10 occupying the developing position is parallel to the photosensitive drum 11 with a predetermined minute gap. As can be seen from FIG. 2, both supporting shafts 12 and 13 of the developing roller 10 are rotatably supported by both end walls 7 and 8 of the developing unit 1, respectively, and are located on the inner side (left side in FIG. 2) of the copying machine main body 2. One support shaft 13 has an end wall 8
And the developing roller gear 14 is fixed to the tip thereof.

An impeller 16 having a large number of blades 15 is provided inside the developer chamber 4.
And the impeller 16 is driven to rotate in the counterclockwise direction in FIG. As a result, the developer in the developer chamber 4
That is, the toner and the carrier are agitated and supplied to the developing roller 10, and the toner and the carrier are agitated to frictionally charge the toner to a predetermined polarity.

Inside the developing roller 10, a magnet 21 having a magnetic pole composed of an S pole and an N pole is fixedly arranged in the casing member 5 of the developing unit 1 as shown by S and N in FIG. As a result, when the developing roller 10 is rotationally driven in the counterclockwise direction in FIG. 1 via the above-described developing roller gear 14, the magnetic developer 9 supplied to the developing roller 10 is generated by the magnetic force of the magnet 21. It is carried on the surface and conveyed counterclockwise. The conveyed developer is scraped by a doctor blade 22 fixed to the casing member 5, and a predetermined amount of the developer that has passed through the blade 22 is sent to the photosensitive drum 11 with its layer thickness regulated.

On the other hand, the photosensitive drum 11 is driven to rotate clockwise in FIG. 1, and an electrostatic latent image corresponding to an original (not shown) image is formed on its surface by a charging / exposure means (not shown). There is. When this latent image reaches the opposing developing area D between the photoconductor drum 11 and the developing roller 10, the charged toner in the developer also conveyed to this area D is electrostatically transferred to the electrostatic latent image to form the latent image. Is visualized. The visible image is transferred onto a transfer paper (not shown) by a transfer device (not shown), and the transferred visible image is fixed by a fixing device (not shown). The developer that has passed through the developing area D is returned to the inside of the developer chamber 4 again, mixed with other developers in this chamber, and used again.

As shown in FIGS. 2 to 4, a positioning pin is provided on the rotation center O of the unit 1 on the rear end wall 8 of the developing unit 1.
78 is projected, and this is the hole 80 of the side plate 79 on the back side of the copier body.
Rotatably supported by a bearing 81 on the unit 1
The end wall 7 on the front side of the support arm 70 of the unit carrier 62 is
Is rotatably supported, and thereby the entire unit 1 is positioned at a predetermined position in the main body of the copying machine and rotatably supported. By pulling out the unit carrier 62 to the front side as shown in FIG.
It can be taken out of the main body of the copier while being supported by.

When a visible image is formed by the red or blue developer contained in the second or third developing device 3R, 3B, the developing unit 1 set at a predetermined position in the copying machine main body is used as a clock in FIG. It is rotationally driven in the direction to bring the developing roller 10R or 10B of the second or third developing device 3R, 3B to the developing position where the developing roller 10 of the first developing device 3 shown in FIG.

For the purpose of rotating the developing unit 1 set in the main body of the copying machine, a drive motor 88 is supported by the unit carrier 62 as clearly shown in FIG. 4 and schematically shown in FIG. Gear 89, also supported by the carrier
Engages with a unit gear 90 formed on the peripheral surface of the rear end wall 8 of the developing unit 1. When the operator selects and pushes a color conversion key switch (not shown) with the developing unit 1 pushed into the copying machine main body 2 and set,
When the drive motor 88 operates, the clutch interposed between the motor 88 and the gear 89 is turned on, and the developing unit 1 rotates about its rotation center O. As a result, the selected developing device, for example, the developing roller 10 of the first developing device 3 as shown in FIGS. 1 and 5, reaches the developing position, where the motor 88 stops operating or the clutch is turned off. The developing unit 1 is stopped and the developing operation described above is performed.

The developing roller brought to the developing position, for example, the developing roller 10 shown in FIGS. 1 and 5 rotates counterclockwise as described above, and this drive is shown in FIGS. 3 and 5. As described above, the rotation of the drive gear 111 rotatably supported by the support shaft 110 of the photosensitive drum 11 is transmitted to the gear 14 of the developing roller 10 brought to the developing position. The developing unit 1 is rotated by the drive motor 88 so that another developing device 3
Similarly, when the R, 3B developing rollers 10R, 10B are brought to the developing position, these developing roller gears 14R, 14B are also driven by the drive gear 1.
It meshes with 11 and is driven to rotate.

By the way, when each of the developing devices 3, 3R, 3B, more accurately, the developing rollers 10, 10R, 10B is brought to the developing position, the rotation of the developing unit 1 is naturally stopped, and the unit 1 is kept at that position. Must be positioned so that each developing device does not move from a predetermined developing position. For this purpose, the illustrated rotary developing device is provided with the developing units 3, 3 of the developing unit 1.
It has stop means for stopping R and 3B at a predetermined developing position facing the photoconductor drum 11.

As shown in FIGS. 4 and 6, the stop means in this example is arranged around the rotation center O of the developing unit 1 and is formed on the developing unit itself by a cam surface 50.
An engaging member composed of a stop roller 117 that abuts on the cam surface 50, and the stop roller 117 forms a cam surface 5
Stop roller 117 on cam surface 50 so that it is constantly pressed against 0.
It has a biasing means constituted by a tension spring 115 for biasing against. In the illustrated example, a cam surface 50 is formed on the end wall 8 on the back side of the developing unit 1, and the cam surface 50 has concave grooves 114, 114R, provided in the same number as the developing devices 3, 3R, 3B.
114B is formed.

The concave grooves 114, 114R, 114B are arranged at equal intervals around the rotation center O of the developing unit 1 (the circumferential intervals of the developing units 3, 3R, 3B), and the stop roller 117 is provided in a position other than that of the developing unit 1. In a part, in the example of the drawing, it is rotatably supported by a lever 116 pivotally supported by a pivot pin 116b projecting from the carrier unit 62. Lever 116 is stop roller 1
Together with 17, the spring 115 is biased toward the cam surface 50 having the concave grooves 114, 114R, 114B.

When each developing roller 10, 10R, 10B reaches the developing position and the driving force for the developing unit 1 is shut off, the stop roller 117 is engaged by the action of the spring 115 in the corresponding concave groove 114, 114R, 114B, Position the developing unit 1, and thus the developing roller brought to the developing position, in that position. As described above, the stop roller 117 is engaged in the concave grooves 114, 114R, 114B formed in the cam surface 50 while pressing the stop rollers 117 in order to position and stop the developing devices 3, 3R, 3B at predetermined developing positions. To do.

When the developing unit 1 rotates clockwise again, the spring 115
The stop roller 117 disengages from the engaged groove and engages with the next groove while rollingly contacting the cam surface. In this way, the desired developing device can be correctly positioned and stopped at the predetermined developing position.

Here, as shown in FIG. 6, the cam surface 50 is rotated by the clockwise rotation of the developing unit 1, and the stop roller 11 is rotated.
When the stop roller 7 starts to engage with one of the plurality of grooves, for example, the groove 114, and reaches the bottom of the groove.
The inclined surface of the concave groove 114 with which the 117 abuts is the first inclined surface 114b,
The cam surface 50 is rotated by the clockwise rotation of the developing unit 1, and the stop roller 117 engaged with the bottom of the concave groove 114.
The second inclined surface 11 with the inclined surface of the concave groove 114 with which the stop roller 117 abuts by the time it leaves the concave groove 114 from its bottom.
4a, the second inclined surface 114a is formed with a gentler gradient than the first inclined surface 114b. Other groove 114R, 114
B is formed in exactly the same way.

As described above, the slope of the second inclined surface 114a with which the stop roller 117 comes into contact when the stop roller 117 comes out of the concave groove as the developing unit 1 rotates is formed gently. Even if the stop roller 117 is not removed from the recess by the solenoid, the stop roller 1
The stop roller 117 can be smoothly removed from the groove by simply pressing 17 against the cam surface 50 by the spring 115 and rotating the developing unit 1. As described above, since the solenoid for removing the stop roller 117 from the concave groove is not necessary, the cost of the developing device can be effectively reduced. Moreover, an adjusting means for adjusting the operation start timing of the solenoid and the rotation start timing of the developing unit is not required, so that the cost of the developing device can be further reduced and the structure thereof can be simplified. Further, in this example, since the locking member is the stop roller 117, the roller 117 makes rolling contact with the surface of the groove. Therefore, the stop roller 117 is rotated along with the rotation of the developing unit 1.
Can be removed from the groove more smoothly.

Further, since the first inclined surface 114b with which the roller 117 contacts when the stop roller 117 enters the concave groove due to the rotation of the developing unit 1 is formed in a steep slope, the stop roller engaged in the concave groove is stopped. The locking function of the developing unit 1 can be enhanced by engaging with the first inclined surface 114b. Stopper 116a that lever 116 hits
Is provided to prevent the roller 117 engaged with the first inclined surface 114b from coming off, a more reliable locking effect can be obtained.

When the developing roller that has reached the developing position rotates counterclockwise in FIG. 5, the developing roller rotates with a large force due to the load of the developer acting on the developing roller. At this time,
Since the developing roller is located far from the center O of the developing unit 1, the developing roller is rotated to rotate the unit 1
Receives a counterclockwise moment about its center O. As a result, if the developing unit 1 rotates counterclockwise, the developing roller 10 shifts from the predetermined developing position, and the predetermined developing operation cannot be performed. However, at this time, the stop roller 117 has the first groove of the steep slope of the first groove.
Since it contacts the inclined surface 114b of the developing unit 1, it acts so as to cancel the above-mentioned moment applied to the developing unit 1 and prevents the rotation of the unit. In other words, in order to cancel out the moment acting on the developing unit during the developing operation,
The stop roller 117 and the steeply inclined first inclined surface 114b are opposed to each other.

Further, in the illustrated example, the rotation direction of the developing unit 1 is set in the direction opposite to the direction of the above moment,
A gear or a drive motor that drives the unit 1 when a moment is generated has a function of preventing the unit 1 from rotating counterclockwise, and it is possible to more reliably prevent an undesired rotation of the unit 1.

At least one of the groove and the surface of the stop roller 117,
An elastic body that does not impair the locking effect is advantageous because it provides a cushioning effect when the roller engages with or disengages from the groove. This can be achieved, for example, by attaching an elastic body such as rubber to the groove or the surface of the stop roller 117.

The present invention can be widely applied to various rotary developing devices other than the illustrated developing device, such as a developing device in a printer.

Effect According to the present invention, when the locking member comes out of the groove as the developing unit rotates, the second locking member contacts the second groove.
Since the slope of the inclined surface is gently formed, the locking member engaged with the groove on the cam surface at the start of rotation of the developing unit can be locked without being forcibly removed from the groove by the solenoid. By simply pressing the member against the cam surface by the biasing means, the locking member can be smoothly released from the concave groove. Further, since it is not necessary to use a solenoid, an adjusting means for matching the operation start timing of the solenoid with the rotation start timing of the developing unit becomes unnecessary. In this way, the structure of the rotary developing device can be simplified and the cost thereof can be effectively reduced.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of the developing device when the developing unit is set in the main body of the copying machine, and FIG. 2 is III-II in FIG.
A cross-sectional view taken along the line I, Fig. 3 is a perspective view showing a state where the storage unit is pulled out from the copying machine main body, and the developing unit is removed from the storage unit. Fig. 4 is a state in which the developing unit is removed. Perspective view of the element
FIG. 5 is an explanatory view for explaining the rotation operation of the developing unit, and FIG. 6 is an explanatory view showing the concave groove and the stop roller as seen from the front side. 1 ... Developing unit, 3,3R, 3B ... Developing device 9,9R, 9B ... Developer, 50 ... Cam surface 114,114R, 114B ... Concave groove 114a ... Second inclined surface, 114b ... First slope

Claims (1)

[Claims] 1. A developing unit having a plurality of developing devices and rotatably supported, and stop means for stopping each developing device of the unit at a predetermined developing position facing the latent image carrier. In the rotary developing device of the image forming apparatus, the stop means is arranged around the rotation center of the developing unit and is in contact with the cam surface formed on the developing unit itself, and the stop surface is other than the developing unit. And a biasing means for biasing the locking member against the cam surface so that the locking member is constantly in pressure contact with the cam surface. Is formed with a recessed groove into which the locking member engages while being pressed against the developing device to position and stop the developing device at a predetermined developing position, and the cam surface is rotated by rotation of the developing unit to rotate the engaging member. The stop member is the concave From the beginning of engaging the groove to the bottom of the groove, the inclined surface of the groove with which the locking member abuts is the first inclined surface, and the cam surface is rotated by the rotation of the developing unit to rotate the concave portion. When the inclined surface of the concave groove with which the locking member that has engaged with the bottom of the groove contacts the locking groove until it leaves the concave groove from the bottom, the second inclined surface is the second inclined surface. 1. A rotary developing device, wherein the rotary developing device is formed to have a gentler slope than that of the first inclined surface.