JPH0350527Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention relates to an electrophotographic developing device in an image recording device such as an electrostatic copying machine or a facsimile machine.
Specifically, two developing device cases are provided around the photoreceptor and between the exposure section and the transfer device, and a developing roller consisting of a developing sleeve and a magnet is placed in each of the cases in close proximity to each other. This invention relates to a developing device for electrophotography.

[Conventional technology]

The above-mentioned developing device has been developed to be compatible with monochrome development, in which one of the different color developers stored in the development case is selected for development, or superposition development, in which the two color developers are sequentially developed. For example, there is one disclosed in Japanese Patent Application Laid-Open No. 58-34469.

In this developing device, a pair of cases for accommodating developers of different colors are separately fixed around the photosensitive surface of a drum-shaped photosensitive member, and a non-magnetic material is placed inside each case. Sleeves formed from the above are rotatably attached to each other, and a magnet roller is rotatably provided within each of the sleeves.

The rotation directions of both sleeves are set to be the same, a doctor blade is disposed on the upper side of each sleeve, and a developer is accommodated in each case.

Development for electrophotography using this developing device involves rotating a magnet roller in a sleeve of a case containing developer of a color involved in development to a position where its main pole faces the photoreceptor, and then connecting the sleeve and photoreceptor. A spike of developer is formed on the sleeve surface facing the body,
On the other hand, the magnetic rollers in the sleeves of colors not involved in development are rotated so that their main poles are deviated from the photoreceptor, and the ears of developer are placed at a position away from the photoreceptor. The influence of toner of unrelated colors is eliminated.

[Problem that the invention attempts to solve]

The conventional developing device described above selectively uses one of a pair of developing sleeves to enable development in different colors. Since the sleeve is rotated in the opposite direction, some of the developer magnetically attracted to the sleeve may be scattered outside the case due to the centrifugal force caused by the rotation of the sleeve.
Therefore, there is a problem in that the developer scattered from the other sleeve gets mixed into the case located on the rotational direction side of the sleeve.

In addition, since the pair of cases are placed close to each other, the magnetism of the magnetic rollers installed in adjacent cases may interfere with each other, disrupting the flow of developer in each case, and causing the blade to disturb the flow of the developer. There is also a problem in that the height of the spikes of the developer, which is regulated by this method, becomes uneven.

The present invention was developed to solve the above-mentioned problems, and it prevents the toner from being mixed in as it scatters as the developing roller rotates. The purpose is to eliminate interference with the developer and prevent disturbances in the spikes of the developer.

[Means for solving problems]

The present invention has been made to solve the above-mentioned problems, and in the electrophotographic developing device described at the beginning, the developing roller on the exposure section side is exposed to light at a portion facing the photoconductor. The rotation direction is set in the opposite direction to the rotation direction of the body, and the developing roller on the transfer device side is set in the forward direction with respect to the photoconductor at a portion facing the photoconductor, and at least one of the developing rollers is made of a non-magnetic material. The invention is characterized in that a doctor blade consisting of the following is disposed between the developing rollers.

[Effect]

In the developing device of the present invention, in a pair of developing rollers, the developing roller on the exposed side faces the photoreceptor in a direction opposite to the rotating direction of the photoreceptor, and the other developing roller faces the photoreceptor. Since each part rotates in the forward direction of the rotation direction of the photoreceptor, even if the toner that is magnetically attracted to each developing roller scatters outside the case as the developing roller rotates, the direction of the scattering will be in the direction of the case. Since there is no direction, it is possible to prevent the scattered developer from getting mixed into the adjacent developing device.

Since the doctor blade made of a non-magnetic material disposed between the developing rollers prevents magnetic interference between the developing rollers, it is also possible to prevent the developer from standing up unevenly due to magnetic interference.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrostatic copying machine in which an embodiment of a developing device of the present invention is shown in the drawings will be described.

FIG. 1 is a sectional view showing the main parts of an electrostatic copying machine. In the figure, reference numeral 1 denotes a drum-shaped photoreceptor, which is attached to a fixed part 2 such as the body of an electronic copying machine. , 52, a copy paper transport section 6, a transfer device 7, a copy paper separation device 8, a copy paper transport device 9, and a cleaning device 10 are arranged in the rotation direction K of the photoreceptor 1 in the above-mentioned order. P is an exposed portion of the photoreceptor 1.

The developing device 51 is configured as follows. That is, a toner replenishment hopper 15 is formed in the upper part of the developing case 11 containing a two-component developer containing a mixture of toner and carrier, and an opening is formed in a portion of the developing case 11 facing the photoreceptor 1. A developing roller _R1 is provided in the section 12.

The developing roller R ₁ is provided with a developing sleeve 13 made of a non-magnetic material, which is rotatably provided with its axis directed in the same direction as the axis of the photoreceptor 1, and a developing sleeve 13 that is spaced apart from each other in the circumferential direction. It consists of a magnet 14 provided.

Reference numeral 16 denotes a toner supply roller provided at the lower part of the hopper part 15, which causes the toner in the hopper part 15 to fall appropriately to the lower part of the case 11. 17 is a developer stirring roller provided at the bottom of the case 11;
18 is a doctor blade made of 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 with the toner hopper section 25 connected thereto is formed in an L-shape, and the protrusion at the lower part thereof is disposed below the case 11. A developing roller consisting of a sleeve 23 made of a non-magnetic material and a magnet 24 is placed inside the opening 22.
It is configured by providing _R2 . 26 is hopper part 2
5 is a toner supply roller, 27 is a stirring roller, and 28 is a doctor blade.

The doctor blades 18 and 28 are made of a non-magnetic material such as aluminum, brass, and ceramics, and are arranged between the developing rollers R ₁ and R ₂ .

As shown in FIG. 2, the developing devices 51 and 52 have support shafts 31 protruding from the top of both axial ends of the photoreceptor 1 of each case 11 and 21, which are fixed to a fixed portion 2 of the machine body or the like. The developing sleeves 13 and 23 are supported by a bearing 32 having a U-shaped cross section so as to be able to swing toward and away from the photosensitive surface of the photoreceptor 1.

33, 33 are the support shafts 31 of the cases 11, 21;
locking pins 34 protruding from the surfaces provided with the respective locking pins;
is an interlocking body formed of a band-shaped plate, whose longitudinally intermediate portion is swingably attached to the fixed portion 2 with a mounting shaft 35, and which has locking recesses 36 provided at both ends thereof. , 36 are linked to the locking pins 33, 33, respectively, so that the cases 11, 21 are connected to the interlocking body 3.
4, they are configured to swing simultaneously and in opposite directions.

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

Reference numeral 37 denotes a drive means for swinging the developing devices 51 and 52, in which a support bar 38 rotatable around an axis parallel to the axis of the photoreceptor 1 is provided on the fixed portion 2, and one of the supporting bars 38 is provided with A cam 39 that contacts the surface of the case 21 of the developing device 52 on the side opposite to the photoreceptor 1 is fixed to the support bar 38;
In addition, slide rods 4 of solenoids 41 and 42 are arranged in long holes at the other end of the link 40 so as to face each other with their rod axes facing in the swinging direction of the case 21.
3 and 44 are locked and connected, and the solenoid 4
3 and 44, one state in which one developing sleeve 13 approaches the photosensitive surface of the photoreceptor 1 (see FIG. 2) and a state in which the other developing sleeve 23 approaches the photosensitive surface (the third state). (see figure).

The state in which the one developing sleeve 13 approaches is due to the gravitational force of the developing device 52, which is large in weight, and the other developing sleeve 23
The state in which the two approaches is due to the excitation force of the solenoid 41 that resists the gravitational force.

Depending on the appropriate setting of the gravity bias, it is also possible to omit the solenoid 42 for switching the one developing sleeve 13 to the approach state.

Next, 45a and 45b are first and second gears having the same number of teeth that mesh with each other, and an input gear 45c meshes with the first gear 45a.

Further, when the one developing sleeve 13 approaches the photosensitive surface, a gear 46 connected to the developing sleeve 13 is provided.
a is engaged with the second gear 45b, and with the other developing sleeve 23 approaching the photosensitive surface, the gear 46b connected to the sleeve 23 is engaged with the first gear 45.
It is designed to mesh with a. Then, as the input gear 45c rotates in the direction A opposite to the rotation direction K of the photoreceptor 1, the one developing sleeve 13 is rotated in the opposite direction with respect to the photoreceptor 1 at the portion facing the photoreceptor 1. The other developing sleeve 23 rotates in the forward direction F with respect to the photoreceptor 1 at the portion facing the photoreceptor 1.

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

When developing with black developer, the solenoid 41 is activated and the cam 39 pushes the developing device 52, as shown in FIG. Then, the sleeve 23 of the developing device 52 approaches the photoconductor, and the sleeve 23 rotates in the direction of arrow F, developing the latent image on the photoconductor 1 with the black toner magnetically attracted to the surface of the sleeve 23. At the same time, due to the swinging of the developing device 52, the interlocking body 3
4 swings about the mounting shaft 35 as a fulcrum, and the developing device 5
1 swings in the direction away from the photoreceptor 1.

As a result, the sleeve 13 of the developing device 51 becomes far away from the photosensitive surface of the photoreceptor 1, so that the red toner in the developing sleeve 13 is attracted to the photoreceptor 1, thereby preventing two-color mixed development. can be avoided.

When developing with red developer, as shown in FIG. 3, when the solenoid 41 is demagnetized, the other solenoid 42 is simultaneously energized to release the pressure on the developing device 52 by the cam 39. As a result, the developing device 52 swings away from the photoreceptor 1 due to the force of gravity, and in conjunction with this, the developing device 51 swings toward the photoreceptor 1. The developing sleeve 13 rotates in the direction of arrow R, and development is performed using only red toner.

In addition, in the above embodiment, the doctor blade 1
Although both the doctor blades 8 and 28 are disposed between the developing rollers R ₁ and R ₂ , either one of the doctor blades 18 and 28 may be disposed at an arbitrary position. and,
As a means of selecting one of two different colors,
Although the developing devices 51 and 52 are configured to swing in opposite directions via the interlocking body 34, as disclosed in the above-mentioned Japanese Patent Laid-Open No. 58-34469 as a conventional technique, the developing devices themselves are In addition to the fixed arrangement, it is also possible to rotate the magnetic roller so that its main pole is far away from the photoconductor, or to slightly shift the position of the developer spike so that the trough of the spike is close to the photoconductor. It is also possible to adopt a configuration such as having them face each other.

Further, it is also possible to apply the present invention to a developing device using a monocomponent developer containing only magnetic toner.

[Effect of idea]

As explained above, according to the electrophotographic developing device according to the present invention, the toner of the developer magnetically attracted to each of the pair of developing sleeves is scattered to the outside of the case by the rotation of each developing sleeve. However, since the scattering directions of the toner are opposite to each other, the scattering toner does not mix into the adjacent developing device, and the problem of development due to two different colors of developer can be solved.

and at least one of the doctor blades provided in the pair of developing devices is formed of a non-magnetic material,
And since it is arranged between the two sleeves,
This doctor blade prevents magnetic interference between the magnets in adjacent developing rollers, thereby preventing disturbances in the flow of developer in each case, and preventing disturbances in the spikes of developer on the surface of the developing sleeve. This makes it difficult for this to occur, and proper development can be carried out well.

[Brief explanation of the drawing]

FIG. 1 is a front view of essential parts of an electrostatic copying machine showing an embodiment of the present invention, and FIGS. 2 and 3 are explanatory views showing a state in which a developing device is alternatively approached. 1... Photoreceptor, 11, 21... Case, 13,
23... Developing sleeve, 14, 24... Magnet, 18, 28... Doctor blade, R ₁ , R ₂
...Developing roller.

Claims (1)

[Scope of utility model registration request] Electrophotography in which two developing device cases are provided around the photoreceptor and between the exposure section and the transfer device, and a developing roller consisting of a developing sleeve and a magnet is placed in each of the cases in close proximity to each other. In the developing device, the developing roller on the exposure section side is arranged in a direction opposite to the rotational direction of the photoconductor at a portion facing the photoconductor, and the developing roller on the transfer device side is arranged in a section facing the photoconductor. A developing device for electrophotography, characterized in that a doctor blade, at least one of which is made of a non-magnetic material, is disposed between the developing rollers, the rotation direction being set in the forward direction with respect to the photoreceptor.