JPS6227774A - Electrophotographic developing device - Google Patents

Abstract

PURPOSE:To avoid bicolor development and to suppress the damage of a photosensitive surface and the degradation of a developer by attaching freely shakably two developing cases each of which is provided with a developing roll consisting of a developing sleeve and a magnet and linking both end sides of an interlocking body, whose intermediate part is supported axially, to both cases. CONSTITUTION:In a developing device 51, a toner replenishing hopper 15 is formed in the upper part of a developing case 11 where a two-component developer where a toner and a carrier are mixed is stored, and a developing roll R1 is provided in an aperture part formed in a position facing a photosensitive body 1. The developing roll R1 consists of a developing sleeve 13 which has the axis directed in the same direction as the axis of the photosensitive body 1 and is provided freely rotatably and consists of a nonmagnetic body and magnets 14 which are provided in the developing sleeve 13 apart from one another in the peripheral direction. A developing device 52 is constituted in the same manner, and a developing roll R2 consisting of a sleeve 23 made of a nonmagnetic material and magnets 24 is provided in an aperture part formed in a position facing the photomagnetic body 1. Rolls R1 and R2 are switched to bring close to or separate from the photosensitive face of the photosensitive body 1 and are freely shaken.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic developing device in an image recording device such as an electrostatic copying machine or a facsimile machine. The present invention relates to a developing device for electrophotography in which a developing case is provided, and a developing roller comprising a developing sleeve and a magnet is provided in each of the developing cases.

[Conventional technology]

The above-mentioned developing device has been developed to be able to handle monochrome development by selecting one of the different color developers stored in the developer case, or superimposed development by sequentially using the two developer colors. For example, JP-A-58-34
There is one disclosed in Publication No. 469.

This developing device has different colors Iri>L', IJL
A pair of cases for accommodating the agent are separately fixed around the photoconductor, and a developing sleeve made of a non-magnetic material is rotatably attached to each case, and electrically connected. A magnet is rotatably provided inside each of the sleeves, and the magnet is placed in the sleeve of the case containing the developer of the color involved in development at a position with its main pole facing the photoreceptor. The developing roller is rotated to form spikes of developer on the roller surface where the developing roller and photoreceptor face each other, and! On the other hand, the magnets in the sleeves of colors that are not involved in development are rotated so that their main poles are deviated from the photoconductor, and the ears of developer are placed at a position away from the photoconductor. This is to eliminate the influence of the developer of the color that is not used.

[Problem that the invention seeks to solve]

The above-mentioned conventional developing device rotates the magnets provided in each sleeve in a counter-rotating manner to change the position of the main pole relative to the photoreceptor, thereby performing development with a developer of a desired color. However, changing the phase of the magnet over 180 degrees using a solenoid is structurally extremely complex, and it is necessary to rotate the magnet slightly to align the troughs of the developer spikes with the photosensitive surface. Although the structure for rotating the magnet becomes simpler when facing the developing roller, since the gap between the developing roller and the photosensitive surface is extremely small, the toner of the developer that is not involved in development is exposed to the photosensitive surface. Some toners from different developers may be developed at the same time due to electrostatic attraction to the latent image surface of the body.

Furthermore, since the magnet is rotated electrically, the ears of developer on each developing roller may be formed opposite to the photosensitive surface due to electrical malfunction, or the ears of developer on each developing roller may be formed opposite to the photosensitive surface. Valleys may be formed facing the photoreceptor surface, and the toners of the two developer colors may come into contact with the photoreceptor at the same time, or neither developer may come into contact with the photoreceptor. Ta.

Furthermore, in conventional developing devices, the ears of developer produced by one of the developing rollers are always in contact with the photosensitive surface.
For example, the rotation of the photoconductor during the warm-up time (the time from turning on the power switch until it is possible to start copying) of the current 4VP, or the rotation of the photoconductor during cleaning. However, the photosensitive surface of the photosensitive member is damaged by the spikes of developer that come into contact with it, and at the same time, the carrier of the developer deteriorates, resulting in a shortened service life.

The present invention has been made in view of the above circumstances, and
The present invention aims to provide a developing device which can reliably avoid unexpected two-color development and can suppress damage to the photosensitive surface and deterioration of the developer through extremely simple structural improvements.

[Means for solving problems]

In order to achieve the above object, the present invention provides the electrophotographic developing device described at the beginning, in which the developing case is provided to be swingable around an axis parallel to the rotational axis of the photoreceptor.
The developing roller is configured to be able to be freely switched between a state in which the developing roller approaches the photosensitive surface of the photoconductor and a state in which it moves away from the photosensitive surface, and each end of the oscillating interlocking body, the intermediate portion of which is pivotally supported, is connected to the developing roller. Separately, in conjunction with each other, a first roller is configured to move the developing rollers so that when one of the developing rollers is in the approaching state, the other is in the separating state.
a second attitude in which one of the developing rollers is in a separated state and the other in an approachable state; and a third attitude in which both developing rollers are separated from the photosensitive surface, and
A feature of the present invention is that a driving means for swinging the developing case or the interlocking body is provided.

[Effect]

According to the above characteristic structure, when one case or the interlocking body swings, the other case swings in the opposite direction to the swing direction of the other case, and during development in the first and second positions. In this case, it is possible to reliably eliminate a situation in which both developing rollers approach or move away from the photoreceptor, and by taking the third attitude, it is possible to move both developing rollers away from the photoreceptor intermediately. Therefore, the spikes of developer formed on both developing rollers can be prevented from coming into contact with the photoreceptor.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. 1st
The figure shows the main parts of the image forming section, and in the figure, 1
1 is a photoreceptor mounted horizontally on the copying machine main body 2, and around the photoreceptor 1 are a charging device 3, an exposure device 4, a pair of developing devices 51 and 52, a paper feeding and conveying device 6, a transfer device 7, and a copying device. Paper separation device 8, paper discharge conveyance device 9, and cleaning device 10
are arranged in this order in the rotational direction K of the photoreceptor l.

The developing device 51 is configured as follows.

That is, a toner replenishment hopper 15 is installed in the upper part of a developing case 11 that accommodates a two-component developer containing a mixture of toner and carrier.
A developing roller R1 is provided in an opening formed in a portion of the developing case 11 facing the photoreceptor l.

The developing roller R5 is spaced apart from a developing sleeve 13 made of a non-magnetic material and is rotatably provided with its axis in the same direction as the axis of the photoreceptor 1. It consists of a magnet 14 provided at.

Reference numeral 16 denotes a toner replenishing roller disposed below the hopper 15, numeral 17 a developer stirring roller disposed below the toner replenishing roller 15, and 18 a doctor blade made of a non-magnetic material.

The structure of the developing device 52 is similar to that of the above-mentioned developing device 51, and the developing case 21 in which the toner hopper 25 is formed is formed in an L-shape, and the protrusion at the lower part thereof is arranged below the case 11. In addition, a developing roller R2 consisting of a sleeve 23 made of a non-magnetic material and a magnet 24 is provided in an opening formed in a portion facing the photoreceptor l.
It consists of

26 is a toner supply roller provided in the hopper 25; 27;
28 is a roller for stirring the developer, and 28 is a doctor blade.

Then, as shown in FIGS. 2 to 4, each case 1
A support shaft 31.31 whose axis is parallel to the axis of the photoreceptor 1 is connected to the upper side of the support shaft 31.21.
1.31 is mounted and supported from above on a bearing 32.32 having a U-shaped cross section, which is connected to the copying machine main body 2, and the developing roller R11R1 is brought close to the photosensitive surface of the photosensitive member l. It can be freely swung to switch to a state where it is separated.

Reference numerals 33 and 33 designate locking pins protruding from the surface of the case 11 and 21 on which the support shaft 31 is provided, and 34 represents an interlocking body formed of a band-shaped plate material, the intermediate portion of which in the longitudinal direction is a mounting shaft. Locking recesses 36a, 36 are swingably attached to the copying machine main body 2 via 35 and provided at both ends thereof.
The locking pins 33, 33 are linked to the locking pins 33, 33, respectively, and the cases 11, 21 are configured to swing simultaneously and in opposite directions via the swing linkage 34.

The locking recess 36a for the locking bottle 33 on the case 11 side of the interlocking body 34 is open at one end in the longitudinal direction of the interlocking body 34, and the other locking recess 36b is opened at the upper surface of the interlocking body 34 in the longitudinal direction. case 11.2.
1, the support shaft 31 can be secured to the bearing 32 and the locking pin 33 to the locking recess 36a (36b) from above, and the case 11.
21 can be pulled out upwards, and by taking out the developing devices 51 and 52 outside the machine, maintenance of the developing devices 51 and 52 can be conveniently performed in a wide space outside the machine. It is now possible to do so.

5 and 6 show a driving means 37 for swinging the developing device 51, 52, in which a loft 38 that is rotatable about an axis parallel to the axis of the photoreceptor 1 is connected to the front and rear side plates. A cam 39, 39 is fixed to the loft 38, and is provided at the loft 38, and is in contact with the surface of the case 21 of the developing device 52, which is larger in weight, on the side opposite to the photoreceptor 1. A spring clutch 41 is provided at one end of the loft 38 for transmitting rotational driving force when the locking member 40 is selectively released from the six pawls a, and a member on the input side of the spring clutch 41 is provided. An input key 10G is provided in series, and a locking member 4 for the pawl a is further engaged by excitation operation.
A solenoid 42 for releasing the 0 lock is provided on a bracket 45 connected to the rear side plate 22.

The cams 39 and 39 resist the gravity of the developing device 52 and move the developing roller l? of the one developing device 52. , the photoreceptor
A first posture (see FIG. 2) X in which the developing roller R of the other developing device 51 is moved away from the photoreceptor 1 via the interlocking body 34 while being pressed toward the side (see FIG. 2);
1, the gravity action of the developing device 52 causes the developing roller R+ of the other developing device 51 to approach the photoreceptor 1 side, and the developing roller R2 of the one developing device 52 is moved away from the photoreceptor 1. 2nd posture (3rd posture) to separate
(See figure) Y, and what is half the amount of rocking of the case 21 in the first posture X and the second posture Y? 8 move,
A third posture in which both the developing rollers R, , R of the reproducing devices 51 and 52 are separated from the photosensitive surface of the photoreceptor l (see FIG. 4).
The cam 39, 39 has the above-mentioned cam acting portion with a phase angle of 180 degrees.

Next, in FIGS. 2 to 4, 43a and 43b are the first and second gears having the same number of teeth that mesh with each other, and the first gear 4
An input gear 43c is meshed with the input gear 3a.

Further, in the first posture X in which the one developing roller R2 approaches the photosensitive surface of the photoreceptor 1, the gear 44a connected to the developing roller R1 meshes with the first gear 43a, and the other developing roller R3 In the second position Y, in which the developing roller R approaches the photosensitive surface of the photoconductor 1, the gear 44b connected to the developing roller R meshes with the second gear 43a, and both developing rollers R+ and Rz are engaged with the photoconductor surface of the photoconductor 1. In the third attitude Z away from the plane, the gear 44a.

A non-transmission state is created in which both gears 44b are disengaged from gears 43a and 43b.

As the input gear 43c rotates in the direction A opposite to the rotation direction of the photoreceptor 1, the one developing roller R2 rotates on the photoreceptor 1 at the portion facing the photoreceptor 1 in the first attitude X. 1, and the other developing roller R1 rotates in the opposite direction R with respect to the photoreceptor 1 at a portion facing the photoreceptor 1.

In the above configuration, for example, a red developer made of red toner and carrier is placed in the case 21 of one developing device 52, and a black developer made of black toner and carrier is placed in the case 11 of the other developing device 51. , development with black toner can be performed when the first attitude X appears, and development with red toner can be performed when the second attitude Y appears, Developing roller R that does not take part in development
Since + or Rt is largely separated from the photosensitive surface of the photosensitive member 1, it is possible to avoid two-color mixed development.

Then, when the third posture Z appears, both developing rollers R11
+? , are both separated from the photoreceptor l. Therefore, if the third posture Z is made to appear during cleaning of the photoreceptor 1 or during warm-up time, the developer ear will not be exposed to the photoreceptor surface of the photoreceptor l. Since there is no contact, it is possible to prevent the photosensitive surface from being damaged by the developer, and the developing roller R+,
Since the drive of Rz is cut off, deterioration of the toner due to the rotation of the developing rollers R, , R, can be effectively prevented.

In the above embodiment, the driving means 37 pushes the developing device 52, but it is also possible to push the developing device 51, or instead of the developing devices 51 and 52, the interlocking body 34 can be swung by the driving means 37. It can also be carried out.

Alternatively, instead of the cam 39, one end of a plate or a rod is attached to the loft 38, and the other end is pivotally attached to the developing device 51, 52 or the interlocking body 34, so that both the forward and backward movements of the developing device 52 can be controlled. , it is also possible to forcibly perform this using the driving means 37, and the driving means 37 can have any configuration. Therefore, the position of the support shaft 31 in the developing device 51, 52 is arbitrary, and it is sufficient if the developing device 51, 52 is made swingable. Further, in addition to the above-described structure of swinging the developing device, a structure of rotating the magnets 14 and 24 as in the conventional example may be adopted.

Further, in the embodiment, the developing devices 51, 5 using two-component developer
Although the present invention has been described with reference to Embodiment 2, it is also possible to apply the present invention to a developing device using a monocomponent developer containing only magnetic toner.

FIG. 7 shows the structure for inserting and removing the developing device on the separate actual flow side.

This is case 11.21 of each developing device f51.52.
A support 46.46 is provided with flange-shaped rails b, b extending in the axial direction of the photoreceptor l on the upper side thereof, and has support guides c, c for the rails b, b.
is provided to be swingable around an axis 47.47 parallel to the axial center of the photoreceptor 1, and the locking pin 33.33 and the swinging interlocking body 3
4 and the interlocking structure including the driving means 37 are disposed on the rear side plate portion, and the developing device 1i! 51.52 can be inserted and removed in the axial direction of the photoreceptor 1, and the developing device 51.52
Both developing rollers RI.

By developing the third attitude Z in which R2 is moved away from the photosensitive surface, it is possible to prevent the photosensitive surface from being scratched and damaged by the spikes of developer.

Note that the support members 46 and 46 are attached to the case 11. , 21 lid.

〔Effect of the invention〕

As described above, the present invention includes two developing cases each provided with a developing sleeve and a developing roller consisting of a magnet, which are swingably mounted, and both ends of the interlocking body with the intermediate portion pivotally supported are connected to each of the two cases. Therefore, when one of the developing rollers swings toward the photosensitive surface of the photoconductor, the other developing roller swings away from the photosensitive surface of the photoconductor. As a result, the separation between the developing roller and the photoreceptor can be increased, and mixed development using two color toners can be reliably avoided.

Moreover, the third roller separates both developing rollers from the photoreceptor.
If the posture is made to appear during warm-up time or when cleaning the photoreceptor, damage to the photoreceptor surface caused by the developer and deterioration of the toner can be effectively suppressed.

Since the two developing cases are moved together by the interlocking body, the above-mentioned counter-swinging of the developing case can be reliably repeated at all times without malfunction, and as a whole, the drawbacks of the conventional system can be reliably overcome with simple improvements. I was able to resolve it.

[Brief explanation of drawings]

FIG. 1 is a front view of essential parts of an image forming section showing an embodiment of the present invention, FIGS. 2 to 4 are explanatory diagrams showing switching states of the developing roller between the first to third postures, and FIG. 6 is a front view of the driving means, FIG. 6 is a side view of the spring clutch, and FIG. 7 is a side view showing the developing device on the separate actual flow side. 1... Photoreceptor, If, 21... Case, 13.2
3...Developing sleeve, 14.24...Magnet,
34... Rocking interlocking body, 37... Drive means, RI+
Rz...developing roller, X...first attitude, Y...second attitude, Z...third attitude.

Claims (1)

[Claims] A developing device for electrophotography, in which two developing cases are provided around a photoreceptor, and a developing roller consisting of a developing sleeve and a magnet is provided in each of the developing cases, and the developing case is connected to the rotation of the photoreceptor. The developing roller is provided so as to be swingable around an axis parallel to the axis, so that the developing roller can be freely switched between a state in which the developing roller approaches the photosensitive surface of the photoconductor and a state in which it moves away from the photosensitive surface, and the intermediate portion is pivotably supported. The end portions of the oscillating interlocking bodies connected to each other are individually linked to the developing roller, and the developing roller is placed in a first posture in which one of the developing rollers is in the approaching state and the other is in the separated state, and a first posture in which the one is in the separated state. and a third position in which both developing rollers are moved away from the photosensitive surface, respectively, and for swinging the developing case or the interlocking body. A developing device for electrophotography, characterized in that it is provided with a driving means.