JP3202834B2 - Multicolor image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic system or the like, and more particularly to a multi-color image forming apparatus such as a full-color image.

[0002]

2. Description of the Related Art FIGS. 11 to 16 show a conventional multicolor image forming apparatus for obtaining a multicolor image using an electrophotographic system.

[0005] The image forming apparatus has an image carrier 1 at a substantially central portion, and image exposure is performed on the image carrier 1 by an optical unit 107 to sequentially form latent images of respective colors. Each time a latent image of each color is formed, the developing cartridges D of each color arranged around the image carrier 1, that is, a yellow developing cartridge Dy, a magenta developing cartridge Dm, a cyan developing cartridge Dc, and a black developing cartridge Db are sequentially formed. The toner image of each color is sequentially formed on the image carrier 1.

A transfer drum 103 is provided on the side of the image carrier 1 opposite to the developing cartridge D, and a sheet 102 is fed from the sheet feeding unit 101 to the transfer drum 103. Paper 102
, The tip of the gripper 103 on the outer periphery of the transfer drum 103
The transfer drum 103 is conveyed while being held on its outer periphery by the rotation of the transfer drum 103. The toner images of the respective colors formed on the image carrier 1 are sequentially superimposed and transferred onto a sheet 102 held on the outer periphery of the transfer drum 103 in an image transfer section facing the transfer drum 103, and are transferred to the sheet 10.
Thus, a multicolor image composed of four color toner images on 2 is obtained.

[0005] Paper 102 onto which four color toner images have been transferred
After that, the toner image is separated from the transfer drum 103 and transported to the fixing unit 104, where the toner image is fixed to mix the toner of each color and fix the toner image on the paper 102 to form a full-color permanent image. Then, the paper is discharged onto a paper discharge tray 106 via a paper discharge unit 105.

The developing cartridges D of the respective colors are held by a holding member (rotary unit) 108 of a developing cartridge switching mechanism, and are rotated to select a developing cartridge. Each developing cartridge D includes a developing device 12 and a shell 13 that covers the developing device 12 and rotatably accommodates the developing device 12 therein.

On one side of the rotary unit 108, there is a driving side plate 7 and a rotation control mechanism provided on the side plate 7, and the rotation center shaft 14 of the developing device 12 projecting from the shell 13 of the developing cartridge D is automatically controlled. Mechanism rotation gear 1
The rotation driving force is transmitted to the developing device 12 via the slide member 48 by being fitted and held in a hole 48a of a member 48 slidably provided on the top. The other end of the developing cartridge D is connected to a hook member 126 as shown in FIG.
Thus, the rotary unit 108 is held on one side opposite to the above.

The developing cartridge D moved to the developing position
Is positioned by pressing against the image carrier 1, but by making the sliding direction of the slide member 48 coincide with the direction of the image carrier 1, the developing cartridge is slid while being held by the slide member 48. You. At a position where the developing cartridge D faces the image carrier 1, the hook member 12
6 is opened to allow the developing cartridge to slide.

The pressing operation of the developing cartridge D at the developing position is performed, as shown in FIG.
, And the drive source 44 controls the driving of the gear 41, so that the pressure control shaft 110 provided at the center of the rotary unit 108 that rotates integrally with the gear 41.
(Which is also the center axis of the rotation of the rotary unit). The driving source 44 is composed of a stepping motor. After accelerating to a constant speed, rotating at a constant speed at the constant speed, then decelerating and stopping, the pressurizing control shaft 110 is pressurized and non-pressurized by 180 degrees each. Rotate.

At the center of the rotary unit 108,
A pressure control mechanism is provided near both ends of the developing cartridge D. The pressurization control mechanism, as shown in FIG.
A semi-cylindrical member 123 fixed to the apparatus main body surrounding the pressure control shaft 110, a rectangular cylindrical pressure member 111 housed slidably in the direction of the developing cartridge D in the semi-cylindrical member 123, Pressing member 1 fixed to pressure control shaft 110
A cam 125, which slides the pressing member 111, housed in the housing 11, and a semi-cylindrical member which urges the pressing member 111 in the direction of the developing cartridge D, It consists of two springs 124 attached to 123.

When the developing cartridge D is not pressurized, FIG.
As shown in FIG. 5, the cam 125 pushes the pressing member 111 to the spring 1.
24, the pressing member 111 is in a retracted state separated from the developing cartridge D.
As shown in FIG. 11, the cam 125 is rotated to
And the pressing member 111 is released from the
The developing cartridge D is pressed in the direction of the developing cartridge D by the force of 4, and the pressing member 111 is pressed.

When the pressurization is released, the developing cartridge D
The slide member 48 of the rotary unit 108 has the spring 5
0, the force returned by the hook member 126 is
Due to the force returned by 6a and the weight of the developing cartridge D, the rotary unit is returned to the normal position.

[0013]

However, in the above-mentioned conventional image forming apparatus, there is a problem that an impulsive sound or vibration is generated when the developing cartridge D comes into contact with the image carrier 1 by the pressure control mechanism. .

To solve this problem, a developing cartridge D
It is only necessary to slow down the moving speed at the time of positioning, but it takes time to switch the developing cartridge D, which leads to a decrease in image forming speed in terms of development. In addition, it is necessary to extend the pressing spring 124 at the time of pressurizing, which causes a problem that the efficiency of using the driving force is poor.

An object of the present invention is to move a developing cartridge of each color, which is moved to a developing position opposed to an image carrier by a holding member of a switching mechanism, at a developing position, so that the developer carrier of the developing cartridge is imaged. When contacting and positioning the carrier, positioning can be performed without significantly increasing the pressurization control time, and noise and vibration associated with the pressurizing operation can be reduced. An object of the present invention is to provide a multicolor image forming apparatus capable of reducing required torque and reducing the cost of a motor of a pressurizing source.

[0016]

[0017]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention relates to a developing cartridge of each color having at least a developing unit having a developer carrier and a developer accommodating unit accommodating the developer,
The developing cartridges of the respective colors are detachably mounted on a holding member and rotated around an axis parallel to the axis of the image carrier, thereby moving to the developing position facing the image carrier and moving to the developing position. Developing for switching the developing cartridge for developing a latent image on the image carrier by pressing the moved developing cartridge in the direction of the image carrier to position the image carrier of the developing cartridge on the image carrier. In a multicolor image forming apparatus having a cartridge switching mechanism, a mechanism for positioning the developing cartridge by pressurizing movement includes a guide member fixed to the image forming apparatus main body and provided at a rotation center of the holding member. A pressing member provided on the guide member so as to be movable in the direction of the developing cartridge, and a pressing spring for urging the pressing member in the direction of the developing cartridge. A first cam for holding the pressing member at a position moved in a direction opposite to the developing cartridge against the pressing spring, a spring holding member to which the pressing spring is attached, and the first cam A second cam for holding the spring holding member at a position moved in the direction of the developing cartridge when holding is released by the first and second shafts, and a shaft on which the first and second cams are fixed, the rotation of which is controlled from the apparatus body side. ,
Wherein the pressing movement in the direction of the image carrier when positioning the developing cartridge is performed at a low speed before and after the developer carrier of the developing cartridge is positioned on the image carrier. This is a multicolor image forming apparatus.

[0018]

[0019]

Embodiment 1 In this embodiment, the developing cartridge D moved to the developing position by the pressing control mechanism shown in FIG. It is characterized in that, when positioning by contacting the positioning portion, the pressing movement of the developing cartridge D is made slow before and after contact with the positioning portion of the image carrier. Other configurations of the multicolor image forming apparatus according to the present embodiment are basically the same as those of the conventional multicolor image forming apparatus described with reference to FIGS. 11 to 16. It will be described using FIG.

FIG. 1 is a block diagram showing a method of controlling the pressure of the developing cartridge in this embodiment, FIG. 2 is a flow chart at that time, and FIG. 3 shows the speed of the pressure control motor.

In this embodiment, as shown in FIG. 1, the pressure control motor (stepping motor) 44 of the developing cartridge D (developing CRG) shown in FIG. ) It is controlled by the CPU based on the signal of 43). Gear 41 of pressure control shaft 110
When the flag 42 is blocking the sensor 43, the developing cartridge D is set in a non-pressurized state.
It is preset in the PU.

Thus, it is possible to detect the state in which the developing cartridge D is not pressurized by the signal of the sensor 43, and to set the width of the flag 42 to the steady angle of the cam 125 in which the pressing member 111 in FIG. By making the size smaller, the rotation operation of the rotary unit 108 in a state where the developing cartridge D is pressurized can be prevented.

The motor 43 has a sensor 43 which outputs a flag 42.
Are driven by the number of steps that are rotated by about 180 degrees after detecting the end of. When the developing cartridge D is pressed and moved in the direction of the image carrier 1 in FIG. 11 by rotating and releasing the pressing control cam 125 in FIG. As shown in (1), after the motor 44 is first accelerated to the speed S1, the motor 44 is driven at a constant speed at the speed S1, and the pressing member 111 is brought into contact with the developing cartridge D to be pressed and moved. Next, the developer carrier 15 of the developing cartridge D
Before the motor 44 comes into contact with the image carrier 1,
2, the developer carrier 15 of the developing cartridge D is brought into contact with the carrier 1 at a low speed to be positioned, and after the contact, the developer carrier 15 is driven again at the speed S1, and then the motor 44 is stopped.

The timing for switching the speed of the motor 44 is determined in consideration of the cam curve of the pressure control cam 125.

As described above, according to this embodiment, the movement of the developing cartridge D in the direction of the image carrier 1 is delayed before and after the developer carrier 15 of the developing cartridge D comes into contact with the image carrier 1. Therefore, positioning can be performed without significantly extending the pressurizing control time, and noise and vibration accompanying the pressurizing operation can be reduced.

Embodiment 2 FIG. 4 is a front view showing a pressure control mechanism for a developing cartridge in another embodiment of the image forming apparatus of the present invention. 5 and 6 are cross-sectional views showing states of the pressurizing control mechanism during pressurization and non-pressurization, respectively, and FIGS. 5 (A) and 6 (A).
Is a sectional view taken along line AA of FIG. 4, FIG. 5 (B) and FIG. 6 (B).
FIG. 5 is a sectional view taken along line BB of FIG. 4.

FIG. 15 shows a pressurizing control mechanism in this embodiment.
Is provided at the center of the rotary unit 108 in the vicinity of both ends of the developing cartridge D, similarly to the conventional pressure control mechanism shown in FIG. The present embodiment is characterized in that a hook member 129 of the pressure spring 124 is provided in the pressure control mechanism of FIG. 15, and a cam 128 for moving the hook member 129 is provided on the pressure control shaft 110. is there.

That is, the pressurizing control mechanism of the present embodiment includes a semi-cylindrical member 123 fixed to the apparatus main body surrounding the pressurizing control shaft 110 and a semi-cylindrical member 123 accommodated in FIG.
A hook member 129 having a curved plate shape slidable in the direction of the developing cartridge D and a hook member 129 which is housed in the semi-cylindrical member 123 and penetrates the hook members 129 on both sides of the hook member 129. A pressurizing member 111 which is inserted into a guide (not shown) and is slidable in the direction of the developing cartridge D, and which is fixed to the pressurizing control shaft 110 and housed in the pressurizing member 111. A cam 125 that slides the member 111;
11 and the semi-cylindrical member 12
And two springs 124 attached to both ends in the up and down direction of the developing unit 3 for urging the pressing member 111 in the direction of the developing cartridge D.
And two cams 128 fixed to the pressure control shaft 110 and provided on both sides of the pressure member 111 for sliding the hook member 129.

When the developing cartridge D is pressurized, FIG.
As shown in FIG. 5B, the pressing member cam 125 is separated from the pressing member 111 to release the restriction of the pressing member 111, and as shown in FIG.
8 pushes the hook member 129 to move the hook member 129 in a direction in which the pressure of the spring 124 increases (toward the developing cartridge). As a result, the pressing member 111 is moved in the direction of the developing cartridge by the force of the spring 124, and protrudes from the respective openings 129 a and 123 a provided in the hook member 129 and the semi-cylindrical member 123 to press the developing cartridge D. Is pressed against the image carrier 1 and positioned.

When the developing cartridge is not pressurized, FIG.
As shown in FIG. 6B, the pressing member 111 is retracted by the pressing member cam 125 to release the pressure, and the pressing member 111 is released.
As shown in (A), the hook member cam 128 is separated from the pressing of the hook member 128 and the pressing member 1 of the spring 124 is moved.
The hook member 128 is moved in a direction in which the pressure exerted on the hook 11 decreases (a retracting direction). Thus, the required torque during non-pressurization from the process of releasing pressurization to the start of pressurizing operation can be made smaller than the required torque during pressurizing operation.

Embodiment 3 FIG. 7 is a flowchart showing a method of controlling the pressure of the developing cartridge in still another embodiment of the image forming apparatus of the present invention, and FIG. 8 shows the speed of the motor for controlling the pressure at that time. FIG.

In the first embodiment, as shown in FIG. 3, the driving speed of the pressure control motor is increased from the speed S2 to the speed S1 after the developing cartridge D comes into contact with the image carrier 1 in this embodiment. In the example, as shown in FIGS. 7 and 8, the feature is that the driving is performed at the low speed S2. As the pressure control mechanism, the pressure control mechanism according to the second embodiment described with reference to FIGS.

When the generated torque is larger in the low-speed region than in the high-speed region due to the characteristics of the motor, the required torque until the developing cartridge D comes into contact with the image carrier 1 can be reduced as in this embodiment. By driving the motor at high speed during the first half of the pressing operation and at low speed during the second half of the pressing operation that requires torque after contact, the torque use efficiency of the motor for pressure control can be improved. Can be planned.

Embodiment 4 FIG. 9 is a flowchart showing a pressure control method for a developing cartridge in still another embodiment of the image forming apparatus of the present invention, and FIG. 10 shows the speed of a pressure control motor at that time. FIG.

In this embodiment, not only during the pressurizing operation of the developing cartridge but also as shown in FIGS. 9 and 10, the pressurizing control motor is driven at a high speed S1 in the first half of the operation when the pressurizing is released. A feature is that the speed is switched to the low speed S2 just before the developing cartridge comes into contact with the rotary unit.

According to this embodiment, it is possible to reduce the impact noise and the vibration during the pressure release operation.

[0037]

As described above, in the multi-color image forming apparatus of the present invention, the developing cartridge moved to the developing position facing the image carrier by the holding member (rotary unit) of the switching mechanism is pressed. When performing positioning by performing pressure movement in the direction of the image carrier by the control mechanism, the speed is reduced before and after the developer carrier of the developing cartridge comes into contact with the positioning part of the image carrier. Positioning can be performed without extension, and noise and vibration associated with the pressing operation can be reduced.

Further, the pressure control mechanism comprises a guide member, a pressure spring, a pressure member, first and second cams, a spring holding member, and a cam control shaft (pressure control shaft). Accordingly, the required torque when the developing cartridge is not pressurized can be reduced, and the cost of the motor of the pressurizing source can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a method for controlling the pressure of a developing cartridge in an embodiment of the multicolor image forming apparatus of the present invention.

FIG. 2 is a flowchart at that time.

FIG. 3 is a diagram showing the speed of a pressure control motor.

FIG. 4 is a front view illustrating a pressure control mechanism of a developing cartridge in another embodiment of the multicolor image forming apparatus of the present invention.

FIG. 5 is a cross-sectional view showing a state of the pressurizing control mechanism when pressurizing.

FIG. 6 is a cross-sectional view illustrating a state in which the pressure control mechanism is not pressurized.

FIG. 7 is a flowchart illustrating a method of controlling the pressure of a developing cartridge in still another embodiment of the image forming apparatus of the present invention.

FIG. 8 is a diagram showing the speed of a pressurization control motor at that time.

FIG. 9 is a flowchart illustrating a method of controlling the pressure of a developing cartridge in still another embodiment of the image forming apparatus of the present invention.

FIG. 10 is a diagram showing the speed of a pressurization control motor at that time.

FIG. 11 is an overall configuration diagram showing a conventional multicolor image forming apparatus.

12 is a front view showing a driving side plate and a developing device automatic control mechanism provided on one side of a rotary unit of the switching mechanism of the image forming apparatus of FIG. 11;

FIG. 13 is a front view showing a holding portion of the developing cartridge on the other side of the rotary unit.

FIG. 14 is a plan view illustrating a pressure control unit of the developing cartridge.

FIG. 15 is a partially cutaway front view showing a developing cartridge and a pressure member thereof.

FIG. 16 is a partially cutaway front view showing a state where the developing cartridge is positioned by pressing by the pressing member of FIG. 12;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 12 Developing device 108 Rotary unit 110 Central axis (pressure control axis) 111 Pressing member 125 Cam 128 Cam 129 Hook member D Developing cartridge

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-317089 (JP, A) JP-A-63-107577 (JP, A) JP-A-2-175176 (JP, A) Jpn. 94845 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/08 503 G03G 15/01 113

Claims (1)

(57) [Claims] A developing unit having at least a developing unit provided with a developer carrying member and a developer accommodating unit accommodating the developer; and an image carrier mounted detachably on the holding member. By rotating around an axis parallel to the axis of the body, it moves to a developing position facing the image carrier, and presses and moves the developing cartridge moved to the developing position in the image carrier direction. A multi-color image forming apparatus, comprising: a developing cartridge switching mechanism for positioning an image carrier of the developing cartridge on the image carrier and switching a developing cartridge for developing a latent image on the image carrier. A guide member fixed to the image forming apparatus main body and provided at a rotation center portion of the holding member; A pressing member movably provided in the direction of the developing cartridge, a pressing spring for urging the pressing member in the direction of the developing cartridge, and the developing member for pressing the pressing member against the pressing spring. A first cam for holding the cartridge at a position moved in a direction opposite to the cartridge, a spring holding member to which the pressure spring is attached, and the spring holding member being moved in the direction of the developing cartridge when holding by the first cam is released. A second cam for holding the developing cartridge in position, and a shaft to which the first and second cams are fixed, the shaft being rotationally controlled from the apparatus main body, wherein the image carrier is positioned when the developing cartridge is positioned. A multicolor image forming apparatus, wherein the pressure movement in the direction is reduced before and after the developer carrier of the developing cartridge is positioned on the image carrier.