JP2507323B2 - Development device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a developing device, and more particularly to a rotary developing device in which a plurality of developing units are rotatably conveyed to a developing area.

(Prior Art) A color copying machine separates an original into three colors of red, green, and blue, and develops an optical image corresponding to each color separately with cyan, magenta, and yellow toners, which are complementary colors of each color. Therefore, a plurality of developing units are required. In this case, if the developing units are separately and independently arranged and arranged side by side around the latent image carrier, the size of the apparatus increases.

Therefore, by arranging a rotating body so as to be close to the latent image carrier, providing a plurality of developing units at a predetermined pitch interval on this rotating body, and sequentially rotating and conveying each developing unit to the developing area, A rotary developing device has been developed in which toner of each color is transferred from each developing unit to an electrostatic latent image on a latent image carrier to perform development.

In this rotary developing device, the above-described developing operation is performed while one of the plurality of developing units is positioned at the developing position. When the developing unit is positioned as described above, at the same time as the positioning is performed, the drive input section of the developer carrier provided in the developing unit is connected to the drive output section of the apparatus main body side drive system. The developer carrying member performs a predetermined toner supply operation by the transmission driving force.

However, in the conventional rotary developing device, when the drive input section of the developing unit is connected to the drive output section of the drive system on the main body side, for example, the gears on both sides do not mesh smoothly and a large impact occurs at the time of connection. I have something to do.
This is because the drive output section of the drive unit on the main body side, for example, the output gear is always connected to the drive source, and the drive output section has almost no degree of freedom.

When such an impact is generated, various parts are often damaged or cause abnormal noise or drive failure.

(Object) Accordingly, an object of the present invention is to provide a rotary type developing device in which each developing unit can be smoothly connected to a main body side driving member.

(Structure) To achieve the above object, a developing device according to the present invention comprises:
The drive system transmits drive force to the drive output unit when the developing unit is positioned at the developing position, and the drive output unit is free when the developing unit is separated from the developing position. A drive force connecting / disconnecting device for maintaining the open state and a friction drive means for frictionally driving the drive output portion are provided.

In the developing device having such a structure, the drive input portion of the developer carrier provided in the developing unit is
When being connected to the drive output section of the main body side drive system, the drive output section of the main body side drive system is maintained in a free open state by the drive force connecting / disconnecting device, and the connection between the two is performed while being naturally synchronized. It is like this.

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

As shown in FIG. 3, the photosensitive drum 1 as a latent image carrier is rotated in the direction of arrow A by a drive mechanism (not shown).

A rotary developing device 2 is arranged near the photosensitive drum 1. In this rotary type developing device 2, a hollow cylindrical casing 3 as a rotating body is used.
Is rotatably provided around the axis 0, and the casing 3
Is rotated in the direction of arrow B by a drive mechanism (not shown). Further, on the inner side of the casing 3, four partition plates 4a, 4b, 4c, 4d extending radially from the shaft 0 are provided, and the partition plates 4a, 4b, 4c, 4d are partitioned. Partition rooms 5a, 5b, 5c and 5d are defined. The developing units 6A, 6B, 6C and 6D for developing the respective colors are housed inside the respective partition chambers 5a, 5b, 5c and 5d.

Each developing unit 6A, 6B, 6C, 6D is provided with a non-magnetic cylindrical sleeve 7a, 7b, 7c, 7d made of aluminum or the like. Each of the cylindrical sleeves 7a, 7b, 7c, 7d is arranged so that a part of each of the openings 8a, 8b, 8c, 8d provided in the casing 3 is exposed to the outside. further,
Inside each of these cylindrical sleeves 7a, 7b, 7c, 7d, magnet bodies 9a, 9b, 9c, 9 are formed by alternately arranging a plurality of different magnetic poles.
d is provided at regular intervals from the inner surface side of the cylindrical sleeves 7a, 7b, 7c, 7d. Then, the magnet bodies 9a, 9b,
By the magnetic force of 9c and 9d, magnetic brushes 11a, 11b, 11c and 11d are formed on the surfaces of the cylindrical sleeves 7a, 7b, 7c and 7d.

The magnetic brushes 11a, 11b, 11c and 11d are cylindrical sleeves 7
At least one of a, 7b, 7c, 7d and magnet bodies 9a, 9b, 9c, 9d is moved in the direction of arrow C by being rotated by a main body side drive system described later.

A developing bias voltage of the same polarity is applied to the cylindrical sleeves 7a, 7b, 7c, 7d and the photosensitive drum 1 by a power supply circuit (not shown). Then, the magnetic brushes 11a, 11b, 11c, 1 on the cylindrical sleeves 7a, 7b, 7c, 7d, respectively.
The moving portion 1d contacts the photosensitive drum 1 on which the electrostatic latent image 12 is formed while moving, and applies toner to the electrostatic latent image 12 to form a visible image 13
Are formed.

In this embodiment, the cylindrical sleeves 7a, 7b, 7c, 7d are
A magnet having an outer diameter of 25 mm is used, and as the magnet bodies 9a, 9b, 9c, 9d, those having a surface magnetic force of the cylindrical sleeves 7a, 7b, 7c, 7d of about 800 gauss are adopted. Thereby, the height of the magnetic brush 11a, 11b, 11c, 11d is 0.3 ~ 5 mm, preferably 0.7 ~
It can be 2 mm.

The developing bias is applied to prevent background stain and adjust image density, and the latent image potential is -800V.
In the case of regular development, it is preferable to apply about 0 to -500V. In the case of reversal development, it is suitable to use a negatively chargeable toner and a bias potential of about -200 to -800V. . The final developing bias value is determined according to the document density or the user's desire.

Further, the magnetic brushes 11a, 11b, 11c, 11 after the development is completed.
Toner collecting rollers 14a, 14b, 1 for collecting residual toner from d
4c and 14d are provided in contact with the magnetic brushes 11a, 11b, 11c and 11d. These toner collecting rollers 14a, 14b, 14
The toner peeling blades 15a, 15b, 15c, 15d are pressed against the c, 14d, and are attached onto the toner collecting rollers 14a, 14b, 14c, 14d by the toner peeling blades 15a, 15b, 15c, 15d. The toner particles are scraped off. The toner scraped off is the toner hoppers 16a, 16b, 16c,
It is supposed to be returned to 16d.

In addition, the toner collecting rollers 14a, 14b, 14c, 14d,
A predetermined bias voltage for toner recovery is applied by a power supply circuit (not shown). The toner collecting bias voltage is for collecting the toner remaining on the magnetic brushes 11a, 11b, 11c, 11d, and has the same level as the developing potential, that is, the toner collecting rollers 14a, 14b, 14d.
When c and 14d are latent image bearing members, it is sufficient to achieve a level at which full surface development is possible. For example, when the latent image is −800V and the developing bias is −200V, the bias voltage for toner recovery is −
It may be about 600V.

Further, it is not necessary to collect all the toner contained in the magnetic brush, and it is sufficient to selectively collect the toner near the surface of the magnetic brush. That is, the minimum condition is the magnetic brushes 11a, 11b, 11c,
To eliminate the difference in toner density distribution on 11d. For example, black areas, halftone areas, and background areas having different toner consumption may be made uniform.

Generally, the toner adhesion amount of the two-component developer is 0.8 to 1.0 mg per unit area, and the relative speed of the photosensitive drum 1 and the magnetic brushes 11a, 11b, 11c and 11d is about 1: 3. The toner is being supplied to the latent image 12 in the state of being supplied with. That is, the magnetic brushes 11a, 11b, 11c and 11d have a toner supply capacity of 0.27 to 0.33 mg per unit area. Therefore, if the toner is collected to exceed the toner supply capacity, the magnetic brushes 11a, 11b, 11c, 11d
The above toner density distribution is made uniform, and the influence of development is completely canceled.

To explain this point in more detail, due to the characteristics of a very general two-component developer having a bulk specific gravity of 2 and a toner concentration of 3%, the weight of a magnetic brush with a height of 1 mm is 0.2 per unit area.
g, and the toner contained therein is 6 mg,
The toner actually contributing to the development is only about 5% in the magnetic brush. In other words, it suffices to recover the toner equivalent to 5%. In the magnetic brush of the present invention, approximately 0.3 mg / cm ² of toner is unevenly distributed near the surface of the magnetic brush by the toner supply roller described later, so that the difference in toner consumption can be effectively eliminated.

Further, the toner collecting rollers 14a, 14b, 14c, 14d are indicated by arrows D.
It is driven to rotate in the direction. This is to prevent the collected toner from reattaching to the magnetic brushes 11a, 11b, 11c, 11d.

Furthermore, toner supply rollers 17a, 17b, 17c, 17d are installed on the downstream side of the toner recovery rollers 14a, 14b, 14c, 14d so as to contact the magnetic brushes 11a, 11b, 11c, 11d. The toner supply rollers 17a, 17b, 17c, 17d are rotationally driven in the direction of arrow E by a rotational drive mechanism (not shown).

In addition, the toner supply rollers 17a, 17b, 17c, 17d,
The toner layer regulating blades 18a, 18b, 18c, 18d are pressed against each other. By the toner layer regulating blades 18a, 18b, 18c, 18d, the toner held on the toner supply rollers 17a, 17b, 17c, 17d is triboelectrically charged while being uniformly thinned.

Further, the toner peeling blades 15a, 15b, 15c, 15 described above
d and the toner layer regulation blades 18a, 18b, 18c, 18d,
The partition plates 4a, 4b, 4c, 4d define toner hoppers 16a, 16b, 16c, 16d each having a predetermined space. These toner hoppers 16a, 16b, 16c, 16d
The toner of each color is accommodated in the inside, and when the toner supply rollers 17a, 17b, 17c, 17d are placed at the developing position (position 17a in the figure), about half the portion is inside the toner. It is arranged to be buried in.

As a result, each color toner stored in the toner hoppers 16a, 16b, 16c, 16d is sent to the magnetic brushes 11a, 11b, 11c, 11d side while being thinned and without leakage. In this case, the toner supply rollers 17a, 17b, 17c, 17d are the magnetic brush 1
The function of uniformly controlling the height of the spikes of 1a, 11b, 11c, and 11d is provided, which contributes to elimination of image density unevenness.

Further, in order to exert the function of uniformly controlling the height of the spikes of the magnetic brushes 11a, 11b, 11c, 11d, between the position in contact with the toner supply rollers 17a, 17b, 17c, 17d and the developing area. The cylindrical sleeves 7a, 7
It may be provided close to b, 7c and 7d.

Furthermore, the toner supply rollers 17a, 17b, 17c, 17d
A predetermined bias voltage for toner supply is applied to the magnetic brushes 11a, 11b, 11b by a power supply circuit (not shown).
Good transfer to c and 11d. The bias voltage for supplying the toner has the same polarity as that of the charged toner and is about 0 to 60.
Set to 0V. It is preferable that the bias voltage for supplying the toner has a polarity opposite to that of the charged toner in order to reliably hold the toner on the supply roller, and a voltage lower than the developing bias is preferably applied.

Here, the sleeves 7a, 7b, 7c, 7d and the toner collecting roller 14
When the voltages applied to the a, 14b, 14c, 14d and the toner supply rollers 17a, 17b, 17c, 17d are V _B , V _R , and V _D , respectively, the polarity is opposite to that of the toner, and | V _R |> It is preferable to set the relationship of | V _B |> | V _D | in terms of the balance of toner on the sleeve. Furthermore, to keep the toner density on the sleeve more _{evenly, | V B | - | V} D |> | V R | - | may be set to a relationship | V _B.

Further, the toner collecting rollers 14a, 14b, 14c, 14d and the toner supply rollers 17a, 17b, 17c, 17d are provided with the casing 3
The scrapers 19a, 19b, 19c and 19d extending from the inner surface side of the are pressed against each other. And this scraper 19a, 19b, 19c,
19d prevents each toner from leaking out.

Further, the power supply circuit for applying the developing bias voltage is provided with an encoder for dividing the output potential into 4 bits and converting it into a signal, and a signal representing the output value of the developing bias voltage is applied to a control circuit (not shown). Has been done. The control circuit includes an arithmetic circuit that calculates an appropriate toner supply bias voltage value corresponding to the developing bias voltage value.

The output signal of the control device is applied to a power supply circuit that supplies a bias voltage for toner supply, and the bias voltage value for toner supply is determined by this. For example, it is controlled so that the difference between both bias voltages is always constant.

Further, the toner collecting rollers 14a, 14b, 14c, 14d and the toner supplying rollers 17a, 17b, 17c, 17d are made of a material having an electric bias effect between the cylindrical sleeves 7a, 7b, 7c, 7d. Any material can be used, and metal, conductive rubber, or the like can be used. Furthermore, each roller 14a, 14b, 14c, 14
d and 17a, 17b, 17c, 17d are magnetic brushes 11a, 11b, 11c, 11
50% to 100% of the height of d is arranged so as to contact with each other at a ratio of occupancy. However, if the absolute value of the air gap is 1 mm or less, it can be installed over 100%. In this case, it is essential to use the electric bias means together.

Further, the rollers 14a, 14b, 14c, 14d and 17a, 17
The outer diameter of b, 17c, 17d can be arbitrarily selected, but due to the demand for miniaturization, 80% or less of the outer diameter of the cylindrical sleeves 7a, 7b, 7c, 7d, or an absolute value of 5 to 60 mm, preferably Is 8 ~
It should be 40 mm.

The amount of toner supplied to the sleeves 7a, 7b, 7c, 7d is
Since it is also determined by the relative speed of the a, 7b, 7c, 7d and the toner supply rollers 17a, 17b, 17c, 17d, the supply amount is made variable with the rotation speed of the toner supply rollers 17a, 17b, 17c, 17d. It may be controlled by That is, the toner concentration is detected by the known sensor means and the toner supply rollers 17a, 17b, 17c,
The toner supply rollers 17a, 17b, 17
The rotation speeds of c and 17d can be controlled. As an example of the toner concentration detecting means, the toner collecting rollers 14a, 14b, 14c,
There is a means for detecting and calculating the reflection density of the toner on 14d.

Further, when the toner layer regulating blades 18a, 18b, 18c, 18d are provided so as to be in pressure contact with the toner supply rollers 17a, 17b, 17c, 17d on the surface opposite to the present embodiment, the toner supply roller 17a, 17b, 17c, 17d will rotate in the direction opposite to arrow E.

Next, the drive system of the cylindrical sleeves 7a, 7b, 7c, 7d or the magnet bodies 9a, 9b, 9c, 9d will be described with reference to FIGS. 1 and 2.

Drive pulley 23 fixed to output shaft 22 of drive motor 21
A transmission belt 26 is hung between the driven pulley 25 rotatably attached to the first transmission shaft 24.
Further, a clutch 27 as a driving force connecting / disconnecting device is mounted on the first transmission shaft 24 so as to be adjacent to the driven pulley 25. The clutch 27 is provided so as to connect or disconnect between the driven pulley 25 and the first transmission shaft 24. As the clutch 27, for example, an electromagnetic type is adopted.

A gear 28 is fixed to the first transmission shaft 24. The gear 28 meshes with a gear 31 fixed to one end of the second transmission shaft 30. Further, the second transmission shaft
A gear 32 is fixed to the other end side of 30. This gear 32
Is meshed with a gear 34 as a drive output portion that is rotatably supported by a bearing 33 on the rotary shaft 1a side of the photosensitive drum 1.

On the other hand, the drive shaft of the cylindrical sleeve 7a (same for 7b, 7c, 7d)
A gear 36 as a drive input unit is fixed to the 35 side. Then, for example, as shown in the drawing, when the developing unit 6A is positioned at the developing position, the gear on the drive input side is
The gear 34 is adapted to mesh with the gear 34 on the drive output side. Further, when the developing unit 6A separates from the developing position, the gear 36 is also disengaged from the gear 34.

Further, the clutch 27 is operated by a controller (not shown). That is, when the developing unit is held at the developing position, the clutch 27 is engaged so that the driving force is transmitted to the gear 34 on the drive output side.
On the other hand, when the developing unit is separated from the developing position, the operation is controlled so that the clutch 27 is disengaged. When the clutch 27 is disengaged, the drive output side gear 34 is maintained in a free open state.

In such a developing device, when the casing 3 is rotationally driven in the direction of arrow A and the developing unit 6A reaches the developing position as shown in the figure, the developing unit 6A is positioned by the control means (not shown). Be done.

At the same time as the positioning of the developing unit 6A, the gear 36 on the drive input side that gives a driving force to the cylindrical sleeve 7a or the magnet body 9a of the developing unit 6A is the gear 34 on the drive output side.
Is fitted to. When these gears 34 and 36 are fitted to each other, the drive system clutch 27 is disengaged, and the drive output side gear 34 is maintained in a free open state. Therefore, when the drive input side gear 36 is meshed with the drive output side gear 34, the drive output side gear 34 is naturally synchronized. As a result, the gears 34 and 36 are smoothly fitted to each other without colliding with each other. Both gears
When 34 and 36 are meshed with each other, the cylindrical sleeve 7a or the magnet body 9a is rotationally driven, and the developing operation is started.

That is, the toner in the toner hopper 16a is held by the rotation of the toner supply roller 17a, and the held toner is triboelectrically charged by the toner layer regulating blade 18a while being uniformly thinned.

Then, the toner is supplied / transferred to the magnetic brush 11a in a uniform thin layer under a predetermined bias voltage for supplying the toner. Then, the magnetic brush 11a to which the toner is attached is transferred to the photosensitive drum 1 side, and the electrostatic latent image 12 formed on the photosensitive drum 1 is developed. After the development is completed, the toner density difference (unevenness) corresponding to the image is generated on the magnetic brush 11a. However, the residual toner on the magnetic brush 11a is on the toner collecting roller 14a side by the bias voltage force for toner collecting. Will be transferred to and recovered.

As a result, the difference in toner concentration of the magnetic brush 11a is eliminated, and uniform density is achieved. That is, the magnetic brush 11a after the toner recovery moves away from the toner recovery roller 14a in the state of the carrier alone or in the state of the uniform toner concentration distribution, and proceeds to the toner supply side again.

The bias voltage value for toner supply is controlled based on the developing bias voltage value. That is, a new amount of toner corresponding to the amount of toner consumed by development is supplied to the magnetic brush 11a.
As a result, the consumption amount and the supply amount of the toner are balanced, and it is possible to prevent an excessive supply or an insufficient supply of the toner.

When the development by the development unit 6A is completed, the casing 3 is rotated again, and the next development unit 6B is moved to the development position by the same operation as described above to perform the development.

As in the present embodiment, if the gear 34 on the drive output side is installed coaxially with the photoconductor drum 1 and at the same time the rotational resistance frictional force of the bearing 33 is set to be slightly strong, the drive output unit When the gear 34 of the
Can be rotated according to the rotation of the photosensitive drum 1. By doing so, the synchronous movement of the drive output side gear 34 can be preliminarily performed before the fitting, and the fitting operation of the drive input side gear 36 on the developing unit side is further facilitated. be able to.

(Effects) As described above, in the developing device according to the present invention, the driving force interrupting device is provided so that the drive output portion of the main body side drive system is maintained in the free open state when the developing operation is not performed. When the drive output section is provided in the main body drive system and the drive output section is left open by the drive force connection / disconnection device, this drive output section is frictionally driven by a drive source different from the drive source of the main body side drive system. Since the friction drive means for driving the main body side drive system is fitted to the drive output section of the main body side drive system when the drive input section of each developing unit is fitted at the start of development, Can be synchronized automatically. Therefore,
According to the present invention, when positioning each developing unit of the rotary developing device at the developing position, the drive input section of the developing unit can be connected very smoothly to the main body side drive output section, It is possible to prevent the occurrence of damage and abnormal noise and improve the reliability of the developing device.

[Brief description of drawings]

FIG. 1 and FIG. 2 are drive force transmission configuration diagrams of a drive system in one embodiment of the present invention, and FIG. 3 is a longitudinal sectional view showing an example of a developing device to which the present invention is applied. 1 ... Photosensitive drum, 6A, 6B, 6C, 6D ... Developing unit, 21 ...
Drive motor, 23,25 ... Pulley, 27 ... Clutch, 28,31,32,
34,36… Gears, 33… Bearings.

Claims (1)

(57) [Claims] 1. A plurality of developing units are provided on a rotating body opposite to a latent image carrier, and each developing unit is rotatably conveyed to a developing area to be positioned at a predetermined developing position. In a developing device in which a drive input portion of a developer carrying member provided in a developing unit is connected to a drive output portion of a drive system of a main body to perform a predetermined developing operation, the developing unit is positioned at a developing position. A driving force interrupting device that transmits a driving force to the driving output part when the developing unit is separated from the developing position, and a driving force interrupting device that opens the driving output part in a free open state; A developing device having a friction drive means for frictionally driving the drive output part by a drive source different from the drive source of the main body side drive system when the drive output part is placed in a free open state. .