JP2002311713A - Rotary developing device - Google Patents

Abstract

(57) [Problem] To improve a stop position accuracy of a rotating body and obtain a high-quality color image with no variation in image density. SOLUTION: A rotating body driving means 10 of a rotating body 3 provided with n developing units 2 rotates the rotating body at every angle of less than (360 / n) degrees, and a developing unit driving means 20 rotates the rotating body. Apart from the body driving means, a rotational force F for rotating the rotating body 3 in the direction of rotation is generated. The engaged portion 5 is provided on the rotating body 3.
Is provided on the main body side of the apparatus, and an engaging member 40 is provided on and off of the engaged portion. When the rotating body rotates by an angle less than (360 / n) degrees, the engaged portion is When the rotating body 3 is rotated by the rotational force F, the engaged portion 5 and the engaging member 40 are engaged and the rotating body is positioned. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary developing device used for a color image forming apparatus (color copier, color printer, etc.).

[0002]

2. Description of the Related Art Generally, as an image forming apparatus for forming a color image, different colors (for example, Y (yellow),
2. Description of the Related Art There has been known an apparatus in which a developing unit for each of C (cyan), M (magenta), and K (black) is switched and developed by facing each other to obtain a color image. Further, as shown in FIG. 3, for example, developing devices 2 (Y,
C, M, K)
N developing units 2 (Y, C, M, and K) are provided at a predetermined pitch (9 in this case) with respect to the rotating body 3.
The rotating body 3 is arranged at a predetermined angle (36 degrees).
There is known a so-called rotary developing device in which the developing units 2 (Y, C, M, K) for different colors are intermittently driven at a pitch of 0 ° / n (in this case, a pitch of 90 °) to switch and face each other. Such a rotary developing device includes, for example, a motor (mainly a stepping motor) 4 and a gear train 4 as rotation driving means for rotating the rotating body 3 in the direction indicated by an arrow.
a, 3a, and by rotating the motor 4 by a predetermined number of revolutions, the rotating body 3 is rotationally driven by a predetermined angle via the gear trains 4a, 3a. In addition, as a method of locking the rotating body 3 at that position after rotating by a predetermined angle, a method of exciting the motor 4 with a hold current and locking it, or locking the motor 4 using static friction torque is generally known. I have. While the rotating body 3 is stopped, the developing device (for example, the developing roller 2a) is driven by a developing device driving unit (not shown).

[0003]

In the conventional rotary developing device described above, the motor 4 is rotated by a predetermined number of rotations, and the rotating body 3 is rotated by a predetermined angle via the gear trains 4a and 3a.
Since the motor 4 is excited by the hold current and locked, or the rotating body is locked by using the static friction torque, the stopping position of the rotating body 3 (therefore, the developing unit 2 with respect to the latent image carrier 1 (Stop position). Gear train 4 serving as rotating body driving means
a, 3a have rattling due to backlash etc.
This is because, even if the motor 4 rotates a predetermined number of rotations, the rotating body 3 may rotate with an error due to the backlash. An example of the maximum amount of the rotation error is indicated by an angle E in FIG. Such a problem may occur not only when the rotating body driving means has a gear train but also when the rotating body driving means has a timing belt or a belt and a pulley.
In forming an image (developing a latent image), the positional accuracy of the developing device with respect to the latent image carrier is, for example, the positional relationship between the developing roller and the surface of the latent image carrier in the developing device, that is, the developing roller is a non-contact type. Is an important factor in determining the gap between the surface of the image carrier and the surface of the developing roller when the developing roller is a contact type, and the contact pressure of the developing roller against the surface of the image carrier when the developing roller is a contact type. If the stop position of the developing device with respect to the carrier varies, the density of the formed image varies. That is, in the conventional rotary developing device, the stop position of the rotating body (the stop position of the developing device with respect to the latent image carrier) varies, and the image density varies, so that a high-quality color image cannot be obtained. There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, improve the stopping position accuracy of the rotating body (therefore, the stopping position accuracy of the developing device with respect to the latent image carrier), and achieve high image quality without variation in image density. It is an object of the present invention to provide a rotary developing device capable of obtaining a color image of (1).

[0005]

According to a first aspect of the present invention, there is provided a rotary developing device, comprising: a rotating body; n developing units provided for the rotating body; Rotator driving means for rotating one of the n developing devices to face a latent image carrier to be developed, and a developing device for driving the developing device facing the latent image carrier A rotary developing device including a driving unit, wherein the rotating unit driving unit is a driving unit that rotates the rotating unit at an angle of less than (360 / n) degrees, and the developing unit driving unit is Apart from the rotator driving means, the rotator is a driving means for generating a rotational force for rotating the rotator in the direction of its rotation, and the rotator is provided with an engaged portion, An engaging member that engages with and disengages from the engaged portion on the main body side When the rotating body rotates by an angle less than (360 / n) degrees, the engaged portion and the engaging member are brought into the engagement ready position, and then the rotating body is driven by the developing device drive. The rotating member is positioned by engaging the engaged portion and the engaging member when rotated by the rotational force of the means. According to a second aspect of the present invention, there is provided the rotary developing device according to the first aspect, wherein the rotating body driving unit is configured to rotate the rotating body by (360 / n) degrees. Assuming that the maximum amount of rotation error is E, the rotating body is ((360 /
n) -E) a drive means for rotating at every angle of degree.

[0006]

According to a first aspect of the present invention, there is provided a rotary developing device, comprising: a rotating body; n developing units provided for the rotating body;
Rotating body driving means for rotating the rotating body to cause one of the n developing devices to face a latent image carrier to be developed; and a developing device facing the latent image carrier. A developing unit driving unit that drives the rotating unit at an angle of less than (360 / n) degrees, and the developing unit driving unit is configured to drive the rotating unit. Apart from the means, the driving means is a driving means for generating a rotational force for rotating the rotating body in the direction of its rotation, and the rotating body is provided with an engaged portion, and provided on the device body side Is provided with an engaging member that engages with and disengages from the engaged portion. When the rotating body rotates by an angle less than (360 / n) degrees, the engaged portion and the engaging member are separated from each other. Then, the rotating body is rotated by the developing device driving means. When the rotating part is rotated by force, the engaged part and the engaging member are engaged with each other to position the rotating body. Therefore, according to the rotary developing device, the following operation and effect can be obtained. can get. That is, the rotator switches the developing device to face the latent image carrier (360 /
When the rotating body is stopped after rotating by n) degrees, first, the rotating body is rotated by an angle of less than (360 / n) degrees by the rotating body driving means, and at that time, the engaged portion of the rotating body and the device body side Are in the engagement preparation position. Then
When the developing device is driven by the developing device driving means, the rotating body further rotates in the rotating direction by the rotational force generated by the driving, and the engaged portion of the rotating body and the engaging member on the apparatus main body side are engaged. As a result, the rotating body is positioned. Therefore, according to this rotary developing device, the rotating body is always positioned at a predetermined position (a position finally rotated by (360 / n) degrees), so that the accuracy of the stop position of the rotating body (and thus the latent The accuracy of the stop position of the developing device with respect to the image carrier) is remarkably improved, and as a result, a high-quality color image having no variation in image density can be obtained. According to the rotary developing device of the second aspect, in the rotary developing device of the first aspect, the rotating body driving unit rotates when the rotating body is to be rotated by (360 / n) degrees. The maximum amount of body rotation error is E
(See FIG. 3), the rotating body is ((360 / n) −
E) Since the driving means rotates at every degree angle, the rotation angle of the rotating body rotated by the rotational force generated when the developing device is driven by the developing device driving means is minimized. Therefore, the rotation angle of the rotating body by the rotating body driving means is (36)
Despite being less than 0 / n) degrees, the rotating body can be positioned as quickly as possible.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1A and 1B are views showing an embodiment of a rotary developing device according to the present invention, wherein FIG. 1A is a schematic front view, and FIG. In FIG.
The same parts as those shown in FIG. 3 are denoted by the same reference numerals.

The rotary developing device includes a rotator 3, n (in this case, four) developing devices 2 (Y, C, M, and K) provided for the rotator 3, and a rotator 3. Is rotated in the direction of arrow A to rotate one of the n developing units 2 (Y, C, M, K) to a latent image carrier 1 to be developed. A developing device driving means 20 for driving a developing device facing the image carrier 1;
The rotating body 3 has a drum shape as a whole, and is rotatably supported by a frame of the apparatus main body.

The rotating body driving means 10 includes a motor (stepping motor) 4 and a gear 4a fixed to an output shaft thereof.
And a gear 3a fixed to the end of the rotating body 3 so as to mesh with the gear 4a.
(0 / n) degrees (in this case, 90 degrees). In this embodiment, when the maximum amount of the rotation error of the rotating body 3 that would occur if the rotating body 3 is to be rotated by 90 degrees is E (see FIG. 3), the rotating body 3 is set to (90− E) It is designed to rotate at every degree angle. The motor 4 is connected to the frame 30 of the apparatus main body.
It is fixed to.

The developing device driving means 20 includes a motor 21, a gear 22 fixed to an output shaft of the motor 21, a gear 23 meshing with the gear 22, a gear 24 meshing with the gear 23, and a gear 24. The gear 25 has a meshing gear 25 and a gear 26 meshing with the gear 25. Motor 2
The gear 1 and the gear 23 are attached to a frame 30 of the apparatus main body, and the gears 24 and 25 are attached to a side plate 3 b of the rotating body 3. The gear 26 is fixed to the shaft end of the developing roller 2a in the developing device 2. The developing roller 2a is rotatably supported by the side plates 3b and 3c of the rotating body 3. In FIG. 1A, gears 24, 25, 26
Shows only the developing unit 2Y for yellow, but the other developing units 2 (C, M, K) are provided with gears 24, 25, and 26 in the same manner. When the rotator 3 rotates and stops at a predetermined position, for example, as shown in FIG. 1A, when the yellow developing unit 2Y stops so as to face the latent image carrier 1, and before that. The gear 24 meshes with the gear 23 (the state before the rotator 3 is completely rotated by 90 degrees (the state before the rotator 3 is completely rotated by 90 degrees)), and only the yellow developing roller 2a is moved in the direction indicated by the arrow ( (The counterclockwise direction). At this time, as is apparent from the rotation direction of the gear 23 in FIG.
, A rotational force F is generated. That is, the developing device driving means 20 is configured to generate a rotating force F for rotating the rotating body 3 in the rotation direction (the direction of the arrow A) separately from the rotating body driving means 10.

The engaged portion 5 is provided on the rotating body 3. The engaged portion 5 in this embodiment is the same as that shown in FIG.
As shown in FIG. 7, four pins are provided on the side plate 3c of the rotating body 3, and four pins are provided corresponding to the respective developing devices 2 (Y, C, M, K).

On the other hand, the engaged portion 5 (Y,
C, M, K) are provided. The engagement member 40 in this embodiment is configured by a lever rotatably supported by a shaft 31 provided on a frame of the apparatus main body, and has a first arm 41 and a second arm 42. I have. A tension spring 32 is provided between the tip of the first arm 41 and the frame 30 of the apparatus main body, and an elongated hole 41 a formed between the tip of the first arm 41 and the shaft 31 is provided with a solenoid 33. Rod 34
Are connected by a pin 34a. The solenoid 33 is attached to the frame 30 of the apparatus main body. Also, the second
The arm 42 has an engaging recess 4 which engages with and disengages from the engaged portion 5.
3, and a contact portion 44 that comes into contact with the engaged portion 5 as a stage before the engagement concave portion 43 and the engaged portion 5 are engaged with each other.

The engaging member 40 as described above is constantly urged clockwise (in the direction of engagement with the engaged portion 5) in FIG. 1B by the pulling force of the spring 32. 2
As shown in (a), when the solenoid 33 is energized and its rod 34 is pulled, it rotates counterclockwise against the urging force of the spring 32, and the engagement recess 43 and the engaged portion 5 The engagement is released. Further, as will be described in detail later, the engagement between the engagement concave portion 43 and the engaged portion 5 is released,
After the rotation of the rotator 3 is started, the power supply to the solenoid 33 is released, and the clockwise rotation is enabled by the pulling force of the spring 32. Further, the rotator 3 continues to rotate (90- E) When rotated by an angle of degree, the engaged portion 5 and the contact portion 44 come into contact with each other, and the engaging member 40 and the engaged portion 5 are brought into the engagement preparation position (pre-engagement stage). (Figure 2
Then, when the rotating body 3 is rotated by the rotation force F by the developing device driving means 20, the engaged portion 5 and the engaging concave portion 4 are rotated.
3 are engaged with each other to position the rotating body 3. The width w of the engagement recess 43 (see FIG. 2A) is
The engagement portion 5 is formed to be slightly larger than the outer diameter. The difference between the width w of the engagement recess 43 and the outer diameter of the engaged portion 5 is
Appropriately set within a range that can secure the stop position accuracy of the rotating body 3 (therefore, the stop position accuracy of the developing device 2 with respect to the latent image carrier 1) necessary to obtain a high-quality color image with no variation in image density. But the smaller the better.

The above-described rotary developing device operates as follows. Now, for example, as shown in FIG. 1, it is assumed that the rotating body 3 is stopped in a state where the developing unit 2 </ b> Y for yellow faces the latent image carrier 1 and the yellow image is being developed. Thereafter, in order to form a cyan image, a latent image writing unit (for example, an exposure unit) (not shown) forms a latent image for cyan on the latent image carrier 1 and a developing unit 2C for cyan is attached to the latent image carrier 1. Point the rotator 3 on the arrow A
When the rotary developing device is rotated by 90 degrees in the direction and stopped, the rotary developing device operates as follows.

(I) As shown in FIG. 2 (a), the solenoid 33 is energized and its rod 34 is pulled so that the engaging member 4
0 rotates counterclockwise, and the engagement recess 43 and the engaged portion 5
The engagement with (Y) is released, and the motor 4 of the rotating body driving means 10 operates to start rotating the rotating body 3 in the direction of arrow A.

(Ii) The rotating body 3 starts rotating in the direction of the arrow A, and the engaged part 5 (Y) which has been engaged so far also moves, and the engaging member 40 is Even if the engagement concave portion 43 and the engaged portion 5 (Y) cannot be engaged again even if they are rotated in the clockwise direction by the urging force (for example, the engaged portion 5 (Y) 2 (a) to the position shown by the solid line), the energization of the solenoid 33 is released,
The engagement member 40 is rotated clockwise by the urging force of the spring 32 until the rod 34 of the solenoid 33 is completely protruded (FIG. 2).
(See virtual line 42 in (b)).

(Iii) When the rotating body 3 continues to rotate in the direction of arrow A and rotates (90-E) degrees from the state shown in FIG. 1, the next engaged portion 5 (C) is engaged. A convex portion 45 on the near side of the contact portion 44 of the second arm 42 of the member 40 (see FIG.
(See (b)) (by slightly turning the engaging member 40 counterclockwise) and dropping into the contact portion 44 (by turning the engaging member 40 clockwise). It comes into contact with the contact portion 44 (see FIG. 2B). That is, the engagement member 40
And the engaged portion 5 (C) are at the engagement preparation position (pre-engagement stage). At this time (when the rotating body 3 is rotated by (90-E) degrees), the driving of the motor 4 of the rotating body driving means 10 is stopped.

(Iv) When the rotating body 3 rotates by (90-E) degrees, the gears 23 and 24 of the developing device driving means 20 (FIG. 1)
(See (a)), the motor 21 operates, the developing roller 2a of the developing device 2C is driven to rotate, and the above-described rotational force F is generated. Rotate in the direction.

(V) When the rotating body 3 is further rotated in the direction of the arrow A by the rotational force F and the engaged portion 5 (C) reaches the engaging concave portion 43 of the engaging member 40, the engaging member 40 Spring 3
With the urging force of 2, the rotating member 3 is positioned at that position by the engagement concave portion 43 and the engaged portion 5 (C) being engaged with each other (see FIG. 1B). This state is a state where the rotating body 3 has just rotated 90 degrees. After that, the above (i)
(V) are repeated in the order of C → M → K to form a full-color image.

As described above, according to the rotary developing device, the following operational effects can be obtained. (A) The rotating body 3 and n provided for the rotating body 3
Developing units 2 and n developing units 2 by rotating the rotating body 3.
And a developing unit driving unit 20 for driving the developing unit 2 facing the latent image carrier 1 with one developing unit facing the latent image carrier 1 to be developed. , The rotating body driving means 10 controls the rotating body 3 to be (360 / n).
A drive means to rotate every angle less than degree,
The developing device driving means 20 is separate from the rotating body driving means 10.
A rotating force F for rotating the rotating body 3 in the direction of rotation.
The rotating body 3 is provided with an engaged portion 5, and the device body is provided with an engaging member 40 which engages with and disengages from the engaged portion 5. When the rotating body 3 is rotated by an angle less than (360 / n) degrees, the engaged portion 5 and the engaging member 40 are brought into the engagement preparation position, and then the rotating body 3 is moved by the developing device driving means 20. Since the engaged portion 5 and the engaging member 40 are engaged with each other when rotated by the rotational force F, and the rotating body 3 is positioned,
The following operation and effect can be obtained. That is, when the rotating body 3 rotates (360 / n) degrees and stops to switch the developing device 2 facing the latent image carrier 1, first, the rotating body driving means 10 causes the rotating body 3 to rotate (360 / n). n)
At this point, the engaged portion 5 of the rotating body 3 and the engaging member 40 on the apparatus main body are at the engagement ready position. Next, when the developing device 2 is driven by the developing device driving means 20, the rotational force F generated by this driving is generated.
As a result, the rotating body 3 further rotates in the rotating direction, and the engaged portion 5 of the rotating body 3 and the engaging member 40 on the apparatus main body side engage to position the rotating body 3. Therefore, according to this rotary developing device, the rotating body 3
Since it is always positioned at a predetermined position (a position finally rotated by (360 / n) degrees), the stop position accuracy of the rotating body 3 (therefore, the stop position accuracy of the developing device 2 with respect to the latent image carrier 1). Is remarkably improved, and as a result, it is possible to obtain a high-quality color image without variation in image density. (B) The rotating body driving means 10 sets the rotating body 3 to (360 /
n) When the maximum amount of the rotation error of the rotating body 3 that would be caused by rotating the rotating body 3 by E (see FIG. 3) is E (see FIG. 3), the rotating body 3 has an angle of ((360 / n) -E) degrees. The rotating body 3 is rotated by the rotating force F generated when the developing device is driven by the developing device driving unit 20 because the driving unit rotates each time.
Becomes the minimum necessary (E above). Therefore,
The rotation angle of the rotating body 3 by the rotating body driving means 10 is (360
/ N) Despite being less than the degree, positioning of the rotating body 3 is possible as quickly as possible.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be appropriately modified within the scope of the present invention.

[0022]

According to any one of the first and second rotary developing devices, the accuracy of the stop position of the rotating body (accordingly, the accuracy of the stop position of the developing device with respect to the latent image carrier) is improved, and there is no variation in image density. A high-quality color image can be obtained. Further, according to the rotary developing device of the present invention, the rotation of the rotating body is performed as quickly as possible even though the rotation angle of the rotating body by the rotating body driving means is less than (360 / n) degrees. Positioning becomes possible.

[0023]

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a rotary developing device according to the present invention, in which (a) is a schematic front view, and (b) is a partially omitted rear view.

FIGS. 2A and 2B are rear views for explaining the operation.

FIG. 3 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 latent image carrier 2 developing device 3 rotating member 5 engaged portion 10 rotating member driving means 20 developing device driving means F rotational force 40 engaging member

Claims (2)

[Claims] 1. A rotating body, n developing units provided for the rotating body, and one of the n developing units, which is a rotating object, is rotated by rotating the rotating body. A rotary developing device comprising: a rotating body driving unit facing an image carrier; and a developing unit driving unit driving a developing unit facing the latent image carrier. A driving unit for rotating the body at an angle of less than (360 / n) degrees, and wherein the developing unit driving unit rotates the rotating body in a direction of its rotation separately from the rotating body driving means. A driving means for generating a rotational force, and the rotating body is provided with an engaged portion, and the device main body side is provided with an engaging member which engages with and disengages from the engaged portion. The rotating body rotates by an angle less than (360 / n) degrees When the rotating member is rotated by the rotational force of the developing device driving means, the engaged portion and the engaging member are engaged. A rotary developing device, wherein a rotating body is positioned together. 2. The rotator driving means controls the rotator to (36
When the maximum amount of rotation error of the rotating body that would be caused by rotating the rotating body by 0 / n) degrees is E, driving to rotate the rotating body at an angle of ((360 / n) -E) degrees 2. The rotary developing device according to claim 1, wherein said rotary developing device is a means.