JPS5912463A - Electrostatic latent image developing device - Google Patents

Abstract

PURPOSE:To prevent effectively smoke scattering, by providing a rotating blade for developer conveyance which is provided in a developer rotatably and a flexible seal member which inhibits the developer from moving in the opposite direction to a conveyance direction. CONSTITUTION:A developing device has the rotating blade 13 for developer conveyance which are provided rotatably in the developer de and the flexible seal plate 14 which inhibits the developer from moving in the opposite drection to the conveyance direction. The 1st electrode plate 11 is provided in opposition to the end part of a scraping plate 6 on the side of a developing sleeve 2. When the developing device is in operation, said rotating blade 13 is driven continuously to rotate to prevent the smoke of the developer generated in a main body casing from scattering out of the developing device effectively.

Description

Detailed Description of the Invention Technical Field The present invention relates to an electrostatic latent image developing device for developing an electrostatic latent image carried on the surface of an electrostatic latent image carrier using a powder developer. .

BACKGROUND OF THE INVENTION Due to the fact that the electrostatic latent image developing device uses a powder developer, when the developing device is in operation, powder smoke of the developer is generated inside the device. Such developer powder passes through a developing opening provided in the lens of the developing device and is scattered out of the developing device, causing various problems. Regarding this, to explain specifically about a powder image transfer type electronic printer incorporating the above-mentioned developing device, as a result of the above-mentioned scattering of powder smoke from the developer, the corona wire of the charger or the nine mirrors in the optical system, etc. The developer will adhere to the lens, etc., and density unevenness will occur in the printed image.

On the other hand, the developer also adheres to the surface of the photoreceptor and transfer paper, causing image fog to occur in the printed image.

Therefore, in the electronic printer, it is necessary to take measures to prevent the scattering of developer powder smoke.

As a typical measure against this problem, an air suction device is provided in the vicinity of the developing opening of the developing device casing, and the air suction device attempts to suck and collect the powder smoke of the developer. However, although such measures can prevent the scattering of powder smoke from the developer, the air suction device itself must be relatively large, and it is difficult to secure an installation location for this purpose. Therefore, the entire electronic printer becomes large and complicated.

OBJECTS OF THE INVENTION An object of the present invention is to provide an electrostatic latent image developing device in which the scattering of developer powder smoke is effectively prevented and the above-mentioned drawbacks are improved.

SUMMARY OF THE INVENTION The gist of the present invention is to prevent the movement of the developer in the direction opposite to the developer transport direction, which occurs due to the rotational drive of the developer transport blade, in the electrostatic latent image developing device according to the present invention. As a result of the provision of the flexible seal member, the development can be carried out by utilizing the depressurizing effect in the developing device Körling that is generated as the transport blade is rotated. The purpose is to effectively prevent powder smoke of the developer from scattering outside the apparatus. In summary, by skillfully utilizing the developer transporting blades, the scattering of the powder smoke can be effectively prevented.

Embodiments An embodiment of an electrostatic latent image developing device according to the present invention will be described with reference to the accompanying drawings. The embodiment described below is shown as being incorporated into a powder image transfer type electronic printer for enlarging and printing micro images, but the electrostatic latent image developing device according to the present invention can be used in other ways. It may also be incorporated into electronic equipment.

In FIG. 1, the electrophotographic photosensitive drum (1) has a circumferential speed of 90B.
It is rotationally driven to move in the direction of arrow (a) at /sθC, and as it moves, an electrostatic latent image is formed on its surface by an image forming device (not shown). Then, an electrostatic latent image developing device (MD) is placed facing the surface.
is installed, and the electrostatic latent image carried on the surface of the photoreceptor drum (1) is developed using a magnetic developer (de). Note that static electricity formed on the surface of the photoreceptor drum (1)
- The potential of the image area of the latent image is approximately 600V, and the potential of the non-image area is approximately 1i00V.

The polarity of this electrostatic latent image is switched to ←) polarity during positive and positive copying, and to ←) polarity during negative and positive copying.

The developing device (MD) generally includes a developing device main body casing having a developing opening (20) in a portion facing the surface of the photoreceptor drum (1), and a developing device main body casing having a developing device opening (20) inside the main body casing. A developing sleeve (2) provided at a position facing the surface of the photoreceptor drum (1) via the magnetic roller (3) provided inside the developing sleeve (2), and a magnetic roller (3) provided inside the developing tank (4). A bucket roller (5) is provided with a part buried in the developer (de) contained
), and a rotating blade (13) for transporting the developer rotatably provided in the developer (de).

Here, the main body casing is composed of the developer tank (4), an arcuate guide plate (9) described later, etc.
The edges of the photosensitive drum (1) side form the edges of the developing opening (20).

Moreover, the inside of the main body casing has a developing sleeve (2
), scrape plate (6), cleaning plate (7) described below
, the support (8), the flexible seal plate (14), etc., the areas (A) and (B) are substantially separated as shown in FIG.
) is divided into two parts. This is important to prevent powder smoke of the developer (de) from scattering outside the developing device (MD), as described later, and when the developing device (MD) is not in operation,
The inside of the main body casing is blocked by each of the members so that air does not flow between the two head regions (A) and (B).

The developing sleeve (4) is made of a non-magnetic conductive material, specifically,
It is made of non-magnetic stainless steel and has a cylindrical shape, and its outer diameter is 31mm. And photosensitive drum (1)
A gap of 0.7 mm is maintained with respect to the surface of
It is rotated at a rotational speed of pm. Further, it is connected to a developing bias power supply (not shown), and the developing bias polarity is switched to 300 .mu. (optional during positive or positive copying), while the polarity is switched to ←) during negative/positive copying. ] is applied. The magnetic roller (3) is formed by sequentially magnetizing S and N poles around its periphery, and is rotated at a rotational speed of 875 rpm in the direction of arrow (b) similarly to the developing sleeve (2). For this reason, the developer (de) supplied onto the circumferential surface of the developing sleeve (2) is attracted to the circumferential surface of the developing sleeve (2) like a magnetic brush, and also moves in the direction of arrow (c) during development. transported.

The developer (de) contained in the developer tank (4) is a so-called two-component magnetic developer made of a mixture of an insulating toner and a magnetic carrier.
It consists of a mixture of an insulating toner with an average particle diameter of 40 μm and a high resistance magnetic carrier with a resistance value of 10”, and in this developer (de), the toner has ←) polarity, while the carrier has ←) polarity, respectively. Frictionally charged.

The bucket roller (5) is rotated at a rotation speed of 22 rpm in the direction of arrow (d) during development, and the bucket roller (5) is accommodated in the developer tank (4) by a plurality of packets provided on its circumferential surface. The developer (de) is scooped up and supplied to the circumferential surface of the developing sleeve (2). Further, for the peripheral surface located below the developing sleeve (2), a scraping plate (6) made of a flexible non-magnetic material such as a 50 μm thick resin film, a thin metal plate, etc., and a cleaning plate ( 7) is attached to the support (8) so as to be pressed in the opposite direction following the rotational direction of the developing sleeve (3) and in the forward direction opposite to the rotational direction of the developing sleeve (3).

On the other hand, above the developing sleeve (2), there is provided an arcuate guide plate (9) that constitutes a part of the upper part of the main casing. The developer (de) adsorbed in the form of a magnetic brush on the circumferential surface of the developing sleeve (2) can come into contact with the inner circumferential surface of the casing (9). An elastic sealing plate (10) made of polyurethane film is attached to the edge of the casing (9) on the photosensitive drum (1) side. The tip of this seal plate (10) is brought into light pressure contact with the surface of the photoreceptor drum (1), and its surface on the developing sleeve (2) side is approximately the same as the inner peripheral surface of the casing (9). It is located on an extension line.

By the way, the seal plate (10) is attached to the photoreceptor drum (1).
), that is, the powder of the developer (de) passes through the gap between the edge of the developing opening (20) located on the upstream side in the direction of arrow (a) and the photoreceptor drum (1). This prevents smoke from scattering outside the developing device (MD), but on the other hand, there is smoke in the developing device (MD) through the gap between the edge located on the downstream side and the photoreceptor drum (1). Developer (
In order to prevent the powder smoke from e) from scattering outside the developing device (MD), the first and second electrode plates (11) and (12), the rotary blade (13), and the flexible seal plate ( 14) is provided.

The first electrode plate (11) is provided facing the end of the scrape plate (6) on the developing sleeve (2) side, and the developer (de) is supplied from the circumferential surface of the developing sleeve (2). It is made of an aluminum plate with a thickness of 1.5 mm and functions as a barrier to prevent the generation of powder smoke of the developer (d e) generated when it is scraped off. The end of the first electrode plate (11) on the photoreceptor drum (1) side is formed into a knife shape, and a gap of 1.0 in. is maintained with respect to the surface of the photoreceptor drum (1). There is. Also, this first
The electrode plate (11) is grounded.

The second electrode plate (12) is attached to the edge of the developing tank (4) on the photosensitive drum (1) side, and is attached to the rotating blade (]
By utilizing the depressurizing effect described later in the main body casing that occurs with the rotational drive in the direction of the arrow <) in 3), it is possible to further ensure the prevention of powder smoke from scattering of the developer (d e). This second electrode plate (12) is also similar to the first electrode plate (12).
Similar to 1), it is made of an aluminum plate with a thickness of 1.0 mm,
The knife-shaped tip is connected to the photoreceptor drum (1
) maintains a gap of 10 hu from the surface. and,
Connected to a bias power supply (not shown) (g) 300V
bias is applied. Therefore, since the first electrode plate (11) is grounded, the first and second electrode plates (11) are grounded.
An electric field with a potential difference of 300 V is formed between the electrode plates (1]) and (12). Due to the presence of this electric field, even if powder smoke of the developer (de) passes between the first and second electrode plates (11) and (12) and is scattered out of the developing device (MD), Even in this case, the powder smoke is electrostatically attracted to either the first or second electrode plate (11) or (1, 2), and its scattering is reliably prevented. That is, the toner in the powder smoke is electrostatically attracted to the second electrode plate (12), while the carrier is electrostatically attracted to the first electrode plate (11), and their scattering is reliably prevented. In addition, the rotating blade (
The first and second electrode plates (11
) and (12) is the rotating blade 1 (13) for transporting the developer.
"l" is the developer (de) stored in the developer tank (4).
) in the direction of arrow (e).
By being rotationally driven at a rotational speed of 2 rpm, the developer (de) present in area (A) is conveyed to area (B). The rotary blade (13) is provided across the entire area in the width direction of the developer tank (4), that is, in the axial direction of the photoreceptor drum (1), and has the same cross-sectional shape over the entire area. This is what we are doing. A flexible seal plate (
]4) is provided. One end of the flexible sealing plate (14) is adhered to the support (8), and the other end (14a) is flexed by itself and is attached to the rotating blade (1).
3) is pressed against the blade part. The tip of the flexible seal plate (14) is always in pressure contact with the blade of the rotary blade (13), but the tip edge (14a)
is intermittently moved toward and away from the blade portion as the rotary blade (13) is rotated. This flexible seal plate (
14) is made of Mylar with a thickness of about 50 μm, but a thin phosphor bronze plate or the like may also be used.

By the way, the flexible seal plate (14) is as described above.
Along with the ms sleeve (2), the scraping plate (6), the cleaning plate (7), and the support (8), the interior of the developing device main body casing is substantially covered, except for the part where the rotating blade (13) is installed. It functions to divide into two parts (A) and 0). Additionally, it also functions to prevent the developer (d e) from moving in the direction of the arrow (y) as the rotary blade (13) is driven to rotate. Therefore, the developer (de) in the area (A) is rotated by the rotating blade (13) in the direction of the arrow (θ).
It is effectively conveyed in the direction of the arrow (X) and reaches the area (B).

According to the inventors' confirmation, due to the effective conveyance of the developer as described above, the area inside the main body casing (
It has also been confirmed that because A) and ([3) are substantially shielded, a depressurizing effect occurs in which the inside of region (A) is placed in a depressurized state. The developing device (MD) is
By effectively utilizing this pressure reducing effect and continuously rotating the rotary blade (13) during operation of the developing device (MD), the lower space of the developing sleeve (2) is maintained in a reduced pressure state, and the photosensitive body drum (1) and second electrode plate (
12) and into the developing device main body casing, the powder smoke of the developer (d e) generated inside the main body casing is directed to the outside of the developing device (MD). It is configured to effectively prevent scattering that leads to +Iz.

Regarding the installation of the flexible seal plate (14),
The bending force of the flexible seal plate (14) itself, the rotating blade (13)
), sufficient consideration must be given to the shape and number of revolutions, etc., and the installation must be such that each of the above-mentioned functions can be performed without any trouble.

In particular, the flexible seal plate (14) tends to be bent toward the region (A) side due to the rotational drive of the rotary blade (13) and lose its function. In order to prevent this, it is desirable that the tip edge (14a) of the flexible seal plate (14) extends below the center of rotation of the rotating blade (13). In addition, the support (8
) and the rotating blade (13), the flexible seal plate (
14), good results can be obtained. Also, the second
Even under the condition shown in the figure, the tip edge (14a) may be in pressure contact with the blade portion of the rotary blade (13), and the flexible seal plate (14) may be bent even in that condition. I'm hopeful. In this state, due to the bending of the flexible seal plate (14), the tip edge (14a) is
f) direction.

In such a configuration, the developer (de) is scooped up by a packet as the bucket roller (5) is driven to rotate, is conveyed to a position where the magnetic force of the magnetic roller (3) is applied, and is transferred to the developing sleeve (2). ) is attracted like a magnetic brush on the circumferential surface. Then, the developing sleeve (2) and the magnetic roller (3)
) is conveyed along the circumferential surface of the developing sleeve (2) in the direction of arrow (C), and reaches the developing area where the developing sleeve (2) and the photoreceptor drum (1) closely face each other. . As a result, the photoreceptor drum (1
) is rubbed by the developer (de), and the electrostatic latent image carried on the surface is developed.

By the way, the developer (
When the developer (de) is transported and when the developer (de) rubs against the surface of the photoreceptor drum (1), powder smoke of the developer (de) is generated. Then, the generated powder smoke of the developer (de) floats upward, passes through the gap between the arcuate casing (9) and the photosensitive drum (1), and is scattered outside the developing device (MD). try However, since the elastic seal plate (]O) is provided in this gap, the scattering is blocked and the scattering is reliably prevented.

Further, the developer (de) that has rubbed the surface of the photoreceptor drum (1) in the development area, that is, passes through the development area and further moves in the direction of arrow (c) along the circumferential surface of the development sleeve (2). The developer (de) being conveyed is scraped off from the circumferential surface of the developing sleeve (2) by the scraping plate (6) and falls downward. Then, the toner is conveyed to the bucket roller (5) side by the rotating blade (13)K, and is appropriately replenished from a toner replenishing device (not shown): it is mixed and stirred with the donor.

It will be used again for development.

In addition, when the developer (ae) is scraped off from the circumferential surface of the developing sleeve (2), and when the developer falls to the lower part of the developing tank (4), the developing agent is still being developed in the lower space of the developing sleeve (2). Powder smoke of the agent (de) is generated. Then, the generated powder smoke of the developer (de) passes through the gap between the second electrode plate (12) and the photosensitive drum (1) and is about to be scattered out of the developing device (MD). However, due to the cooperation between the rotating blade (13) and the flexible seal plate (14), the developer (de) is efficiently transported from the area (A) to the area (B) within the main body casing of the developing device. Therefore, the pressure inside region G) is maintained in a reduced pressure state, and the above-mentioned scattering is reliably prevented. That is, in the gap, an air flow toward the inside of the developing device main body casing is formed due to the above-described pressure reduction effect, and the above-mentioned powder smoke is reliably sent back into the casing.

Effects of the Invention In the electrostatic latent image developing device according to the present invention, the tip portion is in pressure contact with the blade portion of the developer transporting blade, and the rotational movement of the developer transporting blade occurs in the developer transporting direction. Since a flexible sealing member is provided to prevent the developer from moving in the opposite direction, the developer transporting ability of the transport blades is inhibited, and the developer can be transported extremely smoothly within the development facility. It will be held on. In addition, as a result of the provision of the flexible seal member, a pressure reduction effect occurs within the developing device casing as the transport blade rotates, and this pressure reduction effect is utilized to prevent the developer powder from exiting the development device. Since the scattering of smoke is prevented, the scattering of powder smoke can be prevented without making the electrostatic latent image developing device itself large and complicated. Therefore, there is no need to make the entire device, such as an electronic printer, large and complicated in order to prevent the scattering of powder smoke.

[Brief explanation of the drawing]

FIG. 1 is a drawing showing an example of an electrostatic latent image developing device according to the present invention, and FIG. 2 is a drawing showing an enlarged main part thereof. MD...Electrostatic latent image developing device de...Magnetic developer 4
...Developer tank 13...Rotating blade 14...
Flexible seal plate Applicant: Minolta Camera Co., Ltd.

Claims (1)

[Claims] 1. A developer transporting blade that is rotatable in the developer contained in the developer tank and transports the developer in a fixed direction by being rotationally driven, and a blade portion of the transporting blade whose tip portion is a blade portion of the transporting blade. 1, a flexible sealing member that prevents the developer from moving in a direction opposite to the transport direction that occurs when the transport blade is rotated; An electrostatic latent image developing device characterized in that it prevents powder smoke of developer from scattering outside the developing device by utilizing a decompression effect within a developing device casing that occurs during driving.