JPS63161464A - Developing device - Google Patents

Abstract

PURPOSE:To easily separate a pair of toners after forming the pair of a mixed toner and a toner in a developing part by providing an area where plural tuft cutting blades are allowed to face a developing roller and a developer is formed into a thin layer and is carried and allowing a centrifugal force due to rotation of the developing roller or the like to efficiently act. CONSTITUTION:Plural stages 17 and 23 of tuft cutting blades facing a developing roller 16 are provided, and a developer thin layer is formed before the developer is carried to the tuft cutting blade 17 in the last stage. The gap between tuft cutting blades 17 and 23 and the developing roller 16 is made wider toward the upstream side in the developer carrying direction. A recovery means 24 which separates and removes a pair of floating toners detached from the developing roller 16 by the centrifugal force is provided in the space formed with tuft cutting blades 17 and 23 adjacent to each other and the surface of the developing roll 16. That is, the area where a pair of color mixture toners are separated and removed exists just before the tuft cutting blade 17 in the last stage, and a first mixed toner is sufficiently agitated and surely has the polarity inverted to form a pair of toners together with a second toner. Thus, the pair of toners are easily separated by the action of the centrifugal force.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention provides a developing device used for development in the second and subsequent stages of a multicolor recording device that performs multicolor recording during one rotation of a photosensitive drum using electrophotography or electrostatic recording. In order to reverse the charge polarity of the toner from the previous stage of development that has entered the developing device and to facilitate the separation of a pair of toner that has been electrostatically bonded to the toner in the developing device, a plurality of ear cutting blades are attached to the developing roller. By facing the developer roller, an area is created in which the developer is conveyed in a thin layer before it reaches the final stage grain cutting reblade section, and the centrifugal force caused by the rotation of the developing roller etc. is efficiently applied. It is.

[Industrial application field]

The present invention relates to a multicolor recording device using electrophotography or an electrostatic recording method, and more particularly to a two-component magnetic brush developing device.

Recently, there are great expectations for the realization of multicolor recording devices capable of high-speed recording, which is a feature of electrophotographic recording systems.

However, in such an apparatus, there is a problem of color mixing in which toners of different colors are mixed and recorded, and it is desired to develop a technique for preventing color mixing.

[Conventional technology]

FIG. 2 shows a configuration diagram of a conventional two-color recording apparatus.

In the figure, the surface of a photosensitive drum 1 is initially charged uniformly by an initial charger 2. As shown in FIG. Next, the first exposure means 3 performs negative exposure corresponding to the first image information to form a first latent image, and the first developing device 4 forms a first latent image in a first color (for example, black).
A first toner image is formed by reversal development using a two-component magnetic brush developer containing toner.

Furthermore, the recharging unit 5 performs charging again to raise the potential of the first toner image area and bring it closer to the background area potential. Thereafter, similarly to the first toner image formation, negative exposure is performed by the second exposure means 6, reversal development is performed by the second developing device 7, and the second toner image is formed.
A toner image of a color (for example, red) is formed.

As a result, a two-color toner image is formed on the photosensitive drum 1, and the two-color toner image is transferred onto a recording paper 9' by a transfer device 8, and then passes through a fixing section (not shown) to become a printout.

On the other hand, residual toner remaining on the photosensitive drum 1 without being transferred is neutralized by a static eliminator 1O and removed by a cleaner 11. Thereafter, the surface of the photosensitive drum 1 is uniformly neutralized by the optical static eliminator 12, and a new recording cycle begins.

In such two-color recording, when the first toner image passes through the second developing device 7, a portion of the first toner is scraped off, mixed into the second developer, and accumulated.

When the amount of the first toner mixed into the second developer increases, the amount of the first toner mixed into the second developer increases.
At the time of development, development is performed with the first toner mixed, resulting in color mixture.

In order to prevent this color mixture, the present applicant et al.
128594 J, we are proposing a multicolor recording device. This is number 1. This method utilizes the triboelectric series arrangement of the carrier of the second developer and the toner.

FIG. 3 shows a triboelectrification series diagram of the carrier and toner applied to the device of the present invention, where C1 is the first carrier + TI is the first toner + C2 is the second carrier + Tt is the potential of the second toner. show.

By using such a developer, the first developer is mixed into the second developer.
When the toner is mixed in, the charge polarity of the first toner is reversed due to friction with the second toner, and the first toner is electrostatically combined with the second toner, forming a pair of toners having substantially zero charge. This pair of toners has almost the same potential as the second carrier on the triboelectrification series, and the adhesion force with the second carrier becomes small.

Conventionally, in this way, the adhesion force between the pair of toners and the second carrier is reduced, and the centrifugal force caused by the rotation of the developing roller or the rotation of the developer is applied to the pair of toners to separate them from the second developer and mix colors. It was being prevented.

FIG. 4 shows a sectional view of a main part of a second developing device applied to the two-color recording apparatus shown in FIG. In the figure, developer storage section 1
The two-component magnetic brush developer 21 consisting of toner and carrier in the developing roller 3 is agitated and frictionally charged by an agitating means 19 (screw shaft, bucket roller, etc.), and is conveyed counterclockwise over the developing roller 16.

At this time, the magnetic roller 14 is rotated clockwise.
The non-magnetic sleeve 15 containing the inside is being rotated counterclockwise. The developer 21 is formed into a layer of a predetermined thickness by the cutting blade 17, and is used for development in a development area facing the photosensitive drum 1.

Since the toner is consumed by development and the toner concentration becomes uneven, the developer is peeled off from the developing roller 16 by the peeling means 18, the toner concentration is made uniform by the stirring means 19, and a new development cycle begins. If the development continues, the toner will be consumed and the toner density will decrease, so the toner 22 is supplied by the toner supply means 20.

Note that when the first toner mixes into the second developing device y17, the pair of combined toners, the first toner and the second toner, separates from the developing roller 16 due to centrifugal force, is sucked through the air duct 23, and becomes a toner (not shown). The pair is collected by the collection department.

[Problem that the invention seeks to solve]

In the conventional second developing device 7, the charge polarity of the mixed first toner must be reversed before the developer reaches the peeling means 18 after passing through the developing area, and the first toner must form a toner pair with the second toner and be separated. I had to.

This is because the developer stirring means 19 does not exert enough centrifugal force to separate the pair of toners after being peeled off by the peeling means 18, and the developer layer that adheres to the developing roller 16 after stirring is thick. The pair of toners inside the agent layer cannot be separated from the developing roller 16.

Furthermore, since the time after the first toner is mixed is short,
In some cases, the polarity of the entrained toner is not sufficiently reversed. For this reason, there is a problem in that the pair of mixed color toners are transported to the development area, causing color mixing to occur in the second toner image.

Note that color mixing at this time occurs when the pair of toners has a positive charge on the second carrier, causing color mixing in the second image, and when the pair of toners has negative polarity, it adheres to the background area and causes background stains. In this case, the electrostatic force of the toner pair against the carrier is weakened, and the toner pair can have either positive or negative polarity with respect to the second carrier.

[Means for solving problems]

The developing device of the present invention has a developing roller 1 as shown in FIG.
A plurality of stages 17 and 23 of ear-cutting blades facing 6 are provided,
A thin layer of developer is formed before the developer is conveyed to the final stage ear cutting rib 17. At this time, the gap between the ear cutting blade 17.23 and the developing roller 16 is
Regarding the developer transport direction, the upstream side is larger. Then, the adjacent ear cutting blades 17 and 23 and the developing roller 1
The developing roller 16 is moved by centrifugal force into the space formed by the surface of the developing roller 16.
The structure is such that a recovery means 24 (for example, air pulling means) is provided for separating and removing the pair of floating toners that have separated from the toner.

[Effect]

In the developing device of the present invention, the area where the pair of mixed color toners are separated and removed is immediately before the last-stage ear cutting blade 17, and the mixed first toner is sufficiently agitated and the polarity is reliably reversed so that it is separated and removed from the second toner. They form a pair of tona. Further, since another ear cutting blade 23 is provided before the final stage ear cutting blade 17, a thin layer of developer is formed, and a pair of toner particles can be easily separated by the action of centrifugal force.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

Note that, in order to make the explanation of the configuration and operation easier to understand, the same parts are given the same reference numerals throughout all the figures, and repeated explanation thereof will be omitted.

FIG. 1 shows a sectional view of essential parts of a developing device according to an embodiment of the present invention. A case will be described in which the present developing device is applied to a second developing device of a two-color recording device.

In the figure, the developer 21 adhering to the developing roller 16 is thinned by a first ear cutting blade 23, further formed into a layer of a predetermined thickness by a second ear cutting blade 17, and conveyed. Then, development is performed in a development area where the photosensitive drum 1 and the development roller 16 face each other.

Next, a case will be described in which the first toner is mixed into this developing device. The developer containing the first toner mixed in by the peeling means 18 is supplied to the developing roller 16 and conveyed, but because the layer of developer is thick, even if centrifugal force acts, the pair of toners inside the developer are separated. Not done.

Next, by thinning the developer with the first ear cutting blade 23, the toner pair is separated by centrifugal force and collected by the floating toner removing means 24 (for example, an air suction pipe). Furthermore, it is formed into a predetermined developer layer by the second ear cutting blade 17, and is conveyed to the development area.

In this two-color recording, the gap between the second ear cutting blade 17 and the developing roller 16 is 0.3 to 0.8111.
M, the particle size of the first and second carriers is 5 to 50-1
The particle size of the second toner was 5 to 20 μm.

The gap between the first ear cutting blade 23 and the developing roller 16 may be made larger than the gap between the second ear cutting blade 17 and the developing roller 16, and is set to about 0.4 to 5III11.

These values vary greatly depending on the type of developer used and are not limited to the above.Furthermore, although the case where two ear cutting blades are used has been described, the number of stages may be further increased.

Furthermore, it is clear that the present invention is applicable not only to two-color recording but also to multi-color recording.

〔Effect of the invention〕

As explained in detail above, according to the developing device of the present invention,
Since the polarity of the mixed toner of the previous stage development is reversed and the toner is paired with the toner of the development section, the pair of toners can be easily separated, so that good multicolor recording without color mixture can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of essential parts of a developing device according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a conventional two-color recording device, and FIG. 3 is a triboelectric charging of carrier and toner applied to the device of the present invention. Series diagram, FIG. 4 is a sectional view of main parts of the second developing device applied to the two-color recording device of FIG. 2, In FIG. 1, l is a photosensitive drum, 16 is a developing roller,
Reference numerals 17 and 23 indicate ear cutting blades, and 24 indicates floating toner removing means (air suction means), respectively.

Claims (2)

[Claims] (1) A developing roller (16) disposed opposite to the photosensitive drum (1) for conveying the developer, and an ear for cutting the developer into a layer of a predetermined thickness facing the developing roller (16). In a developing device of a multicolor recording device comprising a cutting blade (17), a plurality of stages (17, 23) of ear cutting blades facing the developing roller (16) are provided, and the ear cutting blade (17) is provided with a plurality of stages (17, 23). , 23) and the developing roller (16) is narrowed as it approaches the developing area where the photosensitive drum (1) and the developing roller (16) face each other. 23) and the developing roller (16), a floating toner removing means (24) is provided in the space formed by the developing roller (16). (2) Claim (1) characterized in that air suction means is used as the floating toner removing means (24).
Developing device described in ).