JPH0743550B2 - Developing device for electrophotography - Google Patents

Description

The present invention relates to a developing device for electrophotography in an image recording device such as an electrostatic copying machine or a facsimile, and more specifically, to two developing devices in the peripheral portion of a photoconductor. The present invention relates to a developing device for electrophotography, in which a developing case is provided and a developing roller including a developing sleeve and a magnet is provided in each of the developing cases.

[Conventional technology]

The above-mentioned developing device is a monochromatic developing device which selects and develops one of the different color developers accommodated in the developing case, or
It was developed so as to be compatible with superposition development in which the above two color developers are sequentially developed. For example, JP-A-58-34469.
There is one disclosed in the publication.

This developing device is provided on the peripheral portion of the photosensitive surface of the drum-shaped photosensitive member.
A pair of cases for accommodating developers of different colors are separately fixed and provided, and sleeves made of a non-magnetic material are rotatably mounted in the respective cases and A magnet roller is rotatably provided on the.

In the development of electrophotography by this developing device, the magnet roller in the sleeve of the case accommodating the developer of the color involved in the development is rotated to a position where the main pole of the sleeve faces the photoreceptor, Form the developer spikes on the opposing sleeve surface, while rotating the magnet roller in the sleeve of a color that does not contribute to development so that its main pole is offset from the photoconductor to remove the developer spikes. By placing the toner at a position distant from the photoconductor, the influence of toner of a color that does not contribute to development is eliminated.

[Problems to be solved by the invention]

The above-described conventional developing device rotates one of the magnets provided in each sleeve to change the position of the main pole of the magnet with respect to the photoconductor, thereby developing with a developer of a desired color. It is structurally extremely complicated to change the phase of the magnet roller with a solenoid over 180 degrees. However, by slightly rotating the magnet roller, the valley of the spike of developer faces the photosensitive surface. In such a case, although the structure for driving and rotating is simple, since the gap between the developing sleeve and the photosensitive surface is extremely small, toner of a color that is prevented from being involved in the development is applied to the latent image surface portion of the photosensitive member. Inhalation may result in the development of some of the different colors.

In addition, since the magnet roller is electrically driven, the spikes of each developing sleeve may be formed corresponding to the photosensitive surface due to an electrical malfunction or the like, and the two color developers may simultaneously receive the photoreceptor. There is also a problem that sometimes comes into contact with.

The present invention has been made in order to solve the above problems, and an object thereof is to obtain a developing device for electrophotography which eliminates the possibility of mixing developers of different colors and has no malfunction.

[Means for solving problems]

To achieve the above object, a developing device for electrophotography according to the present invention has two developing cases, each having a developing roller, in a state in which the developing rollers are close to the photosensitive surface and in a state in which they are separated from the photosensitive surface. , Each of which is provided so as to be swingable, and each end portion of the swing interlocking body whose intermediate portion is pivotally supported by a fixed portion such as a machine body is separately linked to the developing case,
It is characterized in that each of the developing rollers is configured to switch to the approaching state in a contradictory manner, and a driving means for swinging the developing case or the swing interlocking member is provided.

[Action]

According to the above-mentioned characteristic configuration, when one developing roller approaches the photosensitive surface, the other developing roller is separated from the photosensitive surface. By linking with the end of the swing interlocking body that is pivotally supported by the fixed part such as the machine body, the back-and-forth swing of the developing case is always repeated without malfunction, so that the two developing rollers are both photosensitive surfaces. The mixed development of the two color toners approaching to each other or the situation where the two developing rollers are separated from the photosensitive surface and the development is impossible is surely prevented, and so-called monochromatic development or superposition development is surely achieved.

〔Example〕

An electrostatic copying machine shown in the drawings will be described as an embodiment of the developing device of the present invention.

FIG. 1 is a sectional view showing a main part of an electrostatic copying machine. In the figure, reference numeral 1 denotes a drum-shaped photoconductor, which is attached to a fixed portion 2 such as a body of an electronic copying machine, and along the peripheral surface of the photoconductor 1, a charging device 3, an exposure device 4, and a pair of developing devices 51. , 52,
The copy paper transport unit 6, the transfer device 7, the copy paper separating device 8, the copy paper transport device 9, and the cleaning device 10 are arranged side by side in the rotation direction K of the photoconductor 1 in the order described above. P is an exposed portion of the photoconductor 1.

The developing device 51 is configured as follows. That is, the toner replenishing hopper 15 is formed on the upper part of the developing case 11 which contains the two-component developer in which the toner and the carrier are mixed, and the opening formed at the portion of the developing case 11 facing the photoconductor 1 is formed. The portion 12 is provided with the developing roller R ₁ .

The developing roller R ₁ is provided with a developing sleeve 13 made of a non-magnetic material, the developing sleeve 13 being rotatably provided with its axis oriented in the same direction as the axis of the photoconductor 1, and the developing sleeve 13 with a circumferential gap therebetween.
And a magnet 14 provided inside.

16 is a toner supply roller provided in the lower part of the hopper unit 15,
With this, the toner in the hopper portion 15 is appropriately dropped to the lower portion of the case 11. Reference numeral 17 is a roller for stirring the developer provided in the lower part of the case 11, and 18 is a doctor blade made of a non-magnetic material.

The structure of the developing device 52 is similar to that of the above-described developing device 51, and the developing case 21 in which the toner hopper portion 25 is connected is formed in an L-shape, and the projecting portion at the lower part thereof is arranged below the case 11. The developing roller R _{2 including} a sleeve 23 made of a non-magnetic material and a magnet 24 is provided inside the opening 22.

Reference numeral 26 is a toner supply roller provided in the hopper portion 25, 27 is a stirring roller, and 28 is a doctor blade.

As shown in FIG. 2, in the developing devices 51 and 52, the support shafts 31 projecting from the upper ends of the axial direction of the photoconductor 1 of the cases 11 and 21 are fixed to the fixing portion 2 such as the machine body. The developing sleeves 13, 23 are supported by a fixed bearing 32 having a U-shaped cross section.
Is swingably attached to the photosensitive surface of the photosensitive member 1 in a state of approaching and a state of separating from the photosensitive surface.

33, 33 are locking pins projectingly provided on the surface of the cases 11, 21 on which the support shaft 31 is provided, and 34 is an interlocking body made of a strip-shaped plate, the middle portion in the longitudinal direction of which is fixed. The case 2 is attached to the portion 2 so as to be swingable by the attachment shaft 35, and the engaging recesses 36, 36 provided at both ends thereof are associated with the engaging pins 33, 33, respectively, so that the cases 11, 21 connect the interlocking body 34. It is configured to swing at the same time and in opposite directions.

The locking recess 36 for the locking pin 33 on the case 11 side of the interlocking body 34 is open at one end side in the longitudinal direction of the interlocking body 34, and the other locking recess 36 is the upper middle surface of the interlocking body 34 in the longitudinal direction. Therefore, in both cases 11 and 21, the support shaft 31 is used as the bearing 32 and the locking pin 33 is used as the locking recess 36 in both cases 11.
In addition, they can be engaged from above. On the contrary, it is easy to pull out the cases 11 and 21 upward, and the maintenance of the developing devices 51 and 52 can be conveniently performed in a wide area outside the machine.

37 is a drive means for swinging with respect to the developing devices 51, 52, which is a support bar 38 rotatable about an axis parallel to the axis of the photoconductor 1.
Is provided on the fixed portion 2, and a cam 39, which is in contact with the surface of the developing device 52 on the side opposite to the photoconductor 1 with respect to the case 21 having a large weight, is fixed to the support bar 38, and , The slide rods 43 and 44 of the solenoids 41 and 42 are locked and connected to the long holes at the other end of the link 40.
A state in which one developing sleeve 23 is brought closer to the photosensitive surface of the photoconductor 1 (see FIG. 2) and another developing sleeve 13 is brought closer to the photosensitive surface by selective excitation of 1,42 (see FIG. 3). ) And can be switched to.

The approaching state of the developing sleeve 13 is due to the gravity bias of the developing device 52, which is large in weight, and the approaching state of the developing sleeve 23 is the exciting force of the solenoid 41 that resists the gravity bias. It is due to.

Therefore, depending on the proper setting of the gravitational force, the solenoid 42 for switching the developing sleeve 13 to the approaching state may be omitted.

Next, 45a and 45b are the first and second teeth with the same number of teeth that mesh with each other.
The input gear 45c is meshed with the first gear 45a.

Further, a gear 46a connected to the sleeve 13 meshes with a second gear 45b while the developing sleeve 13 is close to the photosensitive surface,
In addition, a gear 46b connected to the sleeve 23 meshes with the first gear 45a in a state where the developing sleeve 23 is close to the photosensitive surface. The input gear 45c is the photoconductor 1
When the developing sleeve 13 is rotated in the direction A opposite to the rotating direction K, the developing sleeve 13 is opposed to the photosensitive member 1 at the photosensitive member 1
On the other hand, the developing sleeve 23 rotates in the reverse direction R, and the developing sleeve 23 rotates in the forward direction F with respect to the photoconductor 1 at a portion facing the photoconductor 1.

In the above configuration, for example, the other developing device 51 contains a red developer composed of toner and a carrier, and the one developing device 52 contains a black developer.

When developing with a black developer, the solenoid 41 is actuated and the cam 39 is used to develop the developing device, as shown in FIG.
Press 52. Then, the sleeve 23 of the developing device 52 approaches the photoconductor, and the sleeve 23 rotates in the direction of arrow F to develop the latent image on the photoconductor 1 with the black toner magnetically attracted to the surface of the sleeve 23. As the developing device 52 swings, the interlocking body 34 swings around the mounting shaft 35 as a fulcrum, and the developing device 51 swings in the direction away from the photoconductor 1.

As a result, the sleeve 13 of the developing device 51 is largely separated from the photosensitive surface of the photoconductor 1, so that the developing sleeve
2 due to 13 red toner being attracted to the photoconductor 1
Color mixing development can be avoided.

When developing with a red developer, as shown in FIG.
When the solenoid 41 is demagnetized, the other solenoid 42 is excited at the same time to release the pressing of the developing device 52 by the cam 39. Therefore, the developing device 52 is gravitationally biased by the photosensitive member 1 The developing device 51 swings to the side of the photoconductor 1 in conjunction with this, and the developing device 51 swings toward the photoconductor 1 side.
The developing sleeve 13 of 51 rotates in the direction of arrow R, and development is performed only with red toner.

Although the developing device 52 is pushed by the driving means 37 in the above-mentioned embodiment, the developing device 51 can be pushed, or the interlocking member 34 is swung by the driving means 37 instead of the developing devices 51, 52. It can also be carried out.

Further, instead of the cam 39, one end of a plate or a bar is attached to the support bar 38, and the other end is attached to the developing devices 51, 52 or the interlocking member 34.
It is also possible to forcibly perform both forward and backward movements of the developing device 52 by means of the drive means 37, and the drive means 37 may have any configuration.

Therefore, the position of the support shaft 31 in the developing devices 51, 52 is arbitrary,
It is sufficient if the developing devices 51, 52 can be rocked. Further, in addition to the above-described swinging of the developing device, a configuration in which the magnets 14 and 24 are rotated may be adopted.

It is also possible to apply a developing device for a one-component developer containing only magnetic toner to the present invention.

〔The invention's effect〕

As described above, according to the present invention, each developing roller is provided so that when one developing roller approaches the photosensitive surface, the other developing roller is separated from the photosensitive surface.
Since the developing case is linked to the end of the swinging interlocking body having the intermediate portion pivotally supported, the back-and-forth swinging of the developing case is always repeated without malfunction, so that the two developing rollers are Both are surely prevented from approaching or separating from the photosensitive surface, and therefore, so-called monochromatic development or superposition development is surely performed without causing any development in which two color toners are mixed or no development is possible. To be achieved.

[Brief description of drawings]

FIG. 1 is a front view of a main part of an electrostatic copying machine showing an embodiment of the present invention, FIG. 2 is an explanatory view showing a state where one developing sleeve is brought close to a photosensitive surface, and FIG. FIG. 6 is an explanatory diagram showing a state in which the developing sleeve is brought close to the photosensitive surface. 1 ...... photoreceptor, 11 and 21 ...... case, 13, 23 ...... developing sleeve, 14, 24 ...... magnet, 34 ...... interlocking member, 37 ...... driving means, R _1, R ₂ ...... developing roller.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-57-78555 (JP, A) JP-A-61-201272 (JP, A) JP-A-61-219975 (JP, A) JP-A-61- 264366 (JP, A) JP 61-264367 (JP, A) JP 57-9083 (JP, Y2)

Claims (1)

[Claims] 1. Two developing cases, each having a developing roller, are provided so as to be swingable in a state in which the developing roller approaches the photosensitive surface and in a state in which the developing roller is separated from the photosensitive surface. Each of the end portions of the swing interlocking member pivotally supported by a fixed portion such as a machine body is separately linked to the developing case, and each developing roller is configured to switch to the approaching state in a contradictory manner. A developing device for electrophotography, comprising a driving means for swinging the developing case or the swing interlocking member.