JPS5968763A - Dry type developing device - Google Patents

Abstract

PURPOSE:To cover a developing agent from the outside air so that the agent does not absorb moisture, by recovering the developing agent attracted to the whole surface of a developing roll to a developing agent container tank when no developing work is made. CONSTITUTION:Even when a developing agent 6 attracted to a photosensitive drum 1 in a developing area from an opening 5 to a stopper 4 is consumed by developing works, the developing agent 6 is successively supplied from the developing agent container tank 3 and the tuft height of the developing agent supplied from the tank 3 is maintained at a fixed one which is determined by the number of revolution of a nonmagnetic hollow sleeve 2a and the number of revolution and number of pole of a permanent magnet 2b. When the developing work is terminated, the rotation of the permanent magnet is stopped at first and then the sleeve 2a is stopped with a little time lag. Then whole developing agent 6 attracted to the surface of the sleeve 2a in the developing area from the opening 5 to the stopper 4 is recovered into the container tank 3. Therefore, whole developing agent 6 is contained in the container tank 3 when no developing work is made. In this way, stable development is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a dry developing device that can obtain stable images even when placed in a high-temperature environment for a long period of time.

(Prior art) A dry developing device is provided with a developing roll facing the electrostatic latent image carrier, and this developing roll has a non-magnetic hollow sleeve and a plurality of rollers installed in the space of the non-magnetic hollow sleeve. It is composed of a permanent magnet, and the non-magnetic hollow sleeve (hereinafter referred to as "sleeve") and the permanent magnet are relatively rotatable. A developer storage tank is installed on the same level as the developing roll, and the developer is stored inside this developer storage tank.

The developer magnetically attracted to the sleeve surface is transported by the rotation of the sleeve, the rotation of the permanent magnet, or the rotation of both the sleeve and the permanent magnet, and is discharged ( >) and transported to the development area. In the development area, a portion of the developer adheres to the electrostatic latent image portion of the electrostatic latent image carrier for development, and the remaining developer is stored in an opening provided at the other circumferential end of the developer storage tank. The structure is such that part of the developer is collected inside the developer storage tank.

In a conventional device such as B, developer adheres to the surface of the sleeve outside the developer storage tank even during non-development or when the device is stopped, and is in contact with the outside air over a wide area.

As a result, the developer easily absorbs moisture, resulting in poor fluidity and reduced developer resistance. When the fluidity of the developer deteriorates, agglomerations of the developer tend to occur, and blocking occurs easily in the developing device. Images developed with a developing device in which blocking occurs will appear with white streaks, and the image quality will be extremely poor. Further, since the resistance of the developer has a very large influence on the adhesion of the developer in the development process and the transfer process, a change in the resistance of the developer causes a very large change in image quality.

(Object of the Invention) This invention is characterized in that the developer that is magnetically attracted to the entire circumference of the developing roll surface during development and contributes to development can be collected into a developer storage tank when not in development. The purpose of this is to prevent inhalation of moisture by shielding the developer from the outside air, and will be described in detail below.

(Embodiment) FIG. 1 is a partial sectional view of the vicinity of a developing roll of a dry developing device according to an embodiment of the present invention.

Usually, a photoreceptor drum 1 made of a photosensitive material such as selenium is used as an electrostatic latent image carrier, and the photoreceptor drum 1 rotates at a constant speed in the direction of arrow E in the figure. A developing roll 2 is installed facing the photosensitive drum 1 with a small distance therebetween. The developing roll 2 consists of a non-magnetic hollow sleeve 2a and a plurality of permanent magnets 2b extending in the axial direction and having N and S poles arranged alternately in the circumferential direction within the sleeve space of the sleeve 2a. The permanent magnet 2a and the permanent magnet 2b have a relatively rotatable structure.

A developer storage tank 3 is installed at the same level as the developing roll 2, and is in contact with the developing roll 2 at both ends in the axial direction (not shown) via a flexible material such as felt. The developing roll 2 is in contact with one circumferential end of the developing roll 2 over its entire axial length via a felt (not shown) or the like, and is called a stopper 4 .

The other end of the developing roll 2 in the circumferential direction is opened at minute intervals over the entire axial length to form openings 5.

The developer 6 contained in the developer storage tank 3 is supplied from an upper supply port (not shown) of the developer storage tank 3.

The supply port opens only when supplying, and is tightly closed under normal conditions. Therefore, the developer 6 contained in the developer storage tank 3 can be discharged to the outside only through the opening 5. Next, the operation of this device will be explained.

Before the start of development, the developer 6 does not adhere to the surface of the sleeve 2a outside the developer storage tank 3. When development is started, the permanent magnet 2b first rotates in the direction of arrow A in the figure. When the permanent magnet 2b rotates, the chain of developer rotates in the direction opposite to that of the permanent magnet 2b in accordance with the change in direction of magnetic velocity flow. Therefore, the developer 6 contained in the developer storage tank 3 is discharged through the opening 5 in the direction of arrow C in the figure, and is conveyed to the stopper 4 through the development area. The sleeve 2 is slightly delayed from the rotation of the permanent magnet 2b.
a begins to rotate in the direction of arrow B in the figure at a rotation speed slightly lower than the rotation speed of the permanent magnet 2b. This delay time is
a, the rotation speed of the permanent magnet 2b, and the number of poles of the permanent magnet 2b. Unless standing time is an issue.

It doesn't matter if they rotate at the same time or one of them rotates first.

However, if the rotation of the sleeve 2a becomes extremely slow.

There is a danger that the developer 6 may accumulate on the stopper 4 and fall.

After the sleeve 2a and the permanent magnet 2b rotate in this manner for a while, the lengths of the magnetic brushes formed on the surface of the sleeve 2a become balanced.

Observation of the conveyance state of the developer 6 in the balanced state shows that the lower layer of the developer layer formed on the circumferential surface of the sleeve 2a is conveyed mainly depending on the rotation of the sleeve 2a, and is developed in the direction of the arrow in the figure. It is moving in the direction to collect the developer 6 into the developer storage layer 2. -(6), the upper layer is conveyed mainly depending on the rotation of the permanent magnet 2b and moves in the direction of arrow C in the figure in a direction in which the developer 6 is discharged from the developer storage layer 2. In the vicinity of the storage sleeve 4, the upper layer developer 6, which was conveyed in the direction of the arrow C in the drawing depending on the rotation of the permanent magnet 2b, is transferred to the lower layer in a U-turn shape, and depending on the rotation of the sleeve 2a, the developer 6 is transferred to the lower layer in the direction shown in the arrow C. transported in the opposite direction. In this way, the transport state of the image agent 6 reaches equilibrium,
The electrostatic latent image formed on the photosensitive drum 1 is developed by rubbing.

The developer 6 adheres to the photoreceptor drum 1 during development.

Even if the developer 6 in the layered image area extending from the opening 5 to the storage tank 4 is consumed, it is supplied one after another from the developer storage tank 3, and the number of rotations of the sleeve 2a and the number of rotations and number of poles of the permanent magnet 2b are always maintained. Balance the height of the head of the brightener, which is determined by .

"When the image is finished, the rotation of the permanent magnet 2b is stopped first, and the rotation of the sleeve 2b is stopped a little later, so that the steps 1 to 2 in the developing area extending from the opening 5 to the stopper 4 are stopped."
a. Collect all the surface-adhering developer 6 into the developer storage tank 3.

Therefore, all of the developer 6 is contained in the developer storage tank 3 during non-development.

In addition, in FIG. 1, the stopper 4 serves not only to define a developing area but also to serve as a wall of the developer storage tank 3. If both are made up of separate parts.

The stock hole 4 can be made into a minute gap without using felt or the like.

FIG. 2 is a block diagram showing the configuration of a driving portion of the device shown in FIG. 1.

When printing starts, signals 7a and 7b are simultaneously output from the control circuit 7, and the signal 7a causes the main motor 8, which is the drive source for the photosensitive drum 1, etc., to rotate, causing the transmission drive means 9, such as gears and belts, to be decelerated. The non-magnetic hollow sleeve 2a rotates. At the same time, main motor 8 is activated by signal 7b.
The permanent magnet 2b and the electromagnetic clutch 10 interposed therebetween are connected, and the rotation of the main motor 8 is transmitted through the electromagnetic clutch 10 and the transmission drive means 11, and the permanent magnet 2b also rotates at the same time. As soon as the signals 7a and 7b are output, the developer 6 is discharged from the opening 5 and reaches the stopper 4, and the lengths of the ears of the magnetic brush formed on the surface of the non-magnetic hollow sleeve 2b are balanced. .

In this state, the latent image formed on the photoreceptor drum 1 is developed by rubbing.

After the development is completed, the signal 7b from the control circuit 7 is stopped, the electromagnetic clutch 10 is released, and the rotation of the permanent magnet 2b is stopped. The signal 2a stops after a predetermined set time after the signal 7b stops.

When the main motor 8 stops rotating, the non-magnetic hollow sleeve 2a also stops rotating. All of the developer 6 carried out onto the external non-magnetic hollow sleeve 2a of the developer storage tank 3 during the period from when the signal 7b stops to when the signal 7a stops is collected inside the developer storage tank 3. .

(Effects of the Invention) As described above based on the embodiments, in this invention, all the developer is removed from the developer at the end of development so that the developer does not adhere to the sleeve surface outside the developer storage layer during non-development. Since the developer is collected inside the storage layer, the developer only passes through the small opening (9) and comes into contact with the outside air, so it absorbs very little moisture.

Therefore, the fluidity of the developer does not deteriorate or the resistance changes, and stable development is possible forever.

According to the present invention, since the developer in the developing device can be stored stably for a long period of time with a simple configuration, it can be used as a dry developing device for an electrophotographic device or an electrostatic recording device.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of the vicinity of a developing roll according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the configuration of a driving portion of the apparatus shown in FIG. 1. DESCRIPTION OF SYMBOLS 1... Photosensitive drum (electrostatic latent image carrier), 2... Developing roll, 2a... Non-magnetic hollow sleeve, 2b...
- Permanent magnet, 3... Developer storage tank, 4... Stopper, 5... Opening, 6... Developer. (10) Figure 2 1. Indication of the case 1982 Patent Application No. 177582 2 Name of the invention Dry developing device 3 Relationship to the case by the person making the amendment Patent application Office (105) 1-7 Toranomon, Minato-ku, Tokyo 12 No. 4
, Agent Address (105) 1-7 Ko, Toranomon, Minato-ku, Tokyo
No. 2 No. 6, Contents of the amendment In the attached sheet, Contents of the amendment (1) "Developer storage layer 2" on page 6, lines 19-20 of the specification and lines 2-3 of page 7 of the same book. is corrected as "developer storage layer 3". (2) On page 8 of the same book, lines 5 to 7, it is stated that ``When configuring
・・・・・・・・・・・・・・・・・・Can be made into a gap. "If you configure the
Although it is the same that it is brought into contact with the developing roll 2 using felt or the like, the wall of the developer storage tank 3 can be formed with a small gap without using felt or the like. ” he corrected.

Claims (1)

[Scope of Claims] A dry type developing device that performs development by rubbing a developing roll holding developer supplied from a storage tank on its peripheral surface against an electrostatic latent image carrier. The developing roll is rotatably in contact with the storage tank at one end in the circumferential direction, and the storage tank forms a stop A′ that blocks the flow of the developer at the contact portion and defines a development area;
A discharge opening for discharging the developer is formed on the circumferential surface of the developing roll at the other end, and the developing roll is disposed in a mutually rotatable hollow sleeve made of a non-magnetic material and in the hollow sleeve space. The hollow sleeve and the permanent magnet are rotated at a relative rotation speed that balances the length of the magnetic brush formed on the circumferential surface of the hollow sleeve outside the storage tank during development. The dry developing device is characterized in that the rollers rotate in the same direction, and after the development is completed, the relative rotational speed is changed to collect the developer on the circumferential surface of the hollow sleeve (1) into the storage tank. Device.