JPS60133478A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent an optical system, electrostatic charge system, and conveyance system from being contaminated and form a stable image for a long period by deflecting a wind generated by the movement of a latent image holding member and collecting a developer which is scattered by a developing device to a filter member. CONSTITUTION:Nonmagnetic toner 14 on a sleeve 12 is dislocated to a photosensitive drum 11 according to the potential of a latent image on a photosensitive drum 11 to perform development. An AC voltage is impressed as a developing bias from a power source 9 to the sleeve 12, so the nonmagnetic toner 14 turns into a cloud at the developing part and flows with the wind generated by the rotation of the photosensitive drum 11 and sleeve 12. Then, a hood 19 is projected under the developing part closely to the drum 11 so as to stop the flow of the wind, which is deflected to an air hole 21 provided with a filter 20. The toner in the wind is caught by the filter 20 to prevent the toner from scattering into the machine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus having a developing device for developing a latent image formed on the surface of a latent image holding member in photocopy, static recording, magnetic recording, etc. In particular, by making the surface of the developer carrier on which a thin layer of toner is formed and held face the surface of the latent image holding member (facing with a minute gap or facing in contact), the toner on the thin toner layer side is held as a latent image. The present invention relates to an improvement in an image forming apparatus in which a latent image is developed with toner by selectively making the surface of a member buoyant in correspondence with a latent image pattern.

Figure 1 shows the schematic structure of a typical image forming device of this type that uses monocomponent magnetic toner in the developing part (
(Indicates a non-touch jumping developing type developing device in which the surface of the latent image holding member and toner debris are not in contact with each other.) In the figure, numeral 1 denotes a non-magnetic sleeve as a developer carrier, which is rotationally driven in the direction of arrow a.

Hereinafter, the member 1 will be referred to as a developing sleeve or simply a sleeve.

Reference numeral 2 denotes a fixed magnet roll which is a winning probability generating member and is inserted into the inner space of the sleeve 1, and the developing sleeve 1 rotates around the fixed magnet roll 2. Reference numeral 3 denotes a toner hopper as a developer supply means for the developing sleeve 1, and the developing sleeve 1 is disposed with its substantially right half circumference inserted into the toner hopper 3. Reference numeral 4 is a developer layer thickness regulating member, which is disposed in the center of the upper path of the developing sleeve 1 so that its lower side is close to the sleeve surface with an appropriate minute gap α (for example, 240μ) maintained therebetween. The layer thickness of the magnetic toner that can be passed through the gap α by the magnetic blade and applied onto the sleeve is formed to be thinner than the IIIT gap α. This gap α is smaller than the gap β between the sleeve surface and the latent image holding member. The single layer of toner coated on the sleeve is set so that it does not come into contact with the latent image holding member. 5 is a one-component magnetic toner which is a developer contained in the hopper 3, and 6 is a developing sleeve l on the side opposite to the popper 3 side, with a minute gap β (for example, 300μ) maintained between the developing sleeve l and the sleeve surface. This is a latent image holding member that approaches and passes, and rotates in the direction b, which is the same direction at the closest portion to the rotational movement of the surface of the developing sleeve 1 in the direction a. The part closest to these members 1 and 6 is called a developing part A for convenience.

The magnet roll 2 inserted into the inner space of the developing sleeve 1 has an upper portion "I" corresponding to the magnetic slide 4.
(j % Magnetic poles 21 (cut magnetic poles Nl), 22 (
Developing magnetic pole S1), 23 (transporting magnetic pole N2), 24 (S2
) are placed.

The latent image holding member 6 is, for example, a xerographic photoreceptor on which an electrostatic latent image is formed using Carlson Prokis,
A photoreceptor having an insulating layer on the surface with an electrostatic latent image formed by the NP process described in Publication No. 910, an insulator having a latent image formed by an electrostatic recording method, an insulator having an electrostatic latent image transferred by a transfer method. A drum is a member on which an electrostatic latent image (or a potential latent image or a magnetic latent image) is formed and retained using a body or other appropriate method, and is also referred to as a photosensitive drum or simply a drum in the following description.

The circumferential speed of the member 6 in the developing section A and the circumferential speed of the toner layer on the developing sleeve l must be equal. This is because, as described in Japanese Unexamined Patent Publication No. 55-120042, if the circumferential speeds of the two are different, directionality will appear in the developed image. Taking advantage of the fact that the peripheral speed of a single layer of supported toner is slightly faster, the peripheral speed of the developing sleeve 1 is slightly slower than that of the latent image holding member 6, thereby improving the directionality of the developed image. This is to eliminate unevenness.

On the other hand, as described above, it is necessary to hold the latent image holding member 6 and the developing sleeve 1 with a small gap β (for example, 300 μ). This has conventionally been achieved by the method shown in FIG.

FIG. 2 is a plan view of the developing section A seen from the X direction in FIG. , is of a type in which this is brought into contact with the latent image holding member 6, and the developing sleeve 1 and the spacer roller 7 are designed to rotate at independent angular velocities.

Incidentally, in FIG. 2, the latent image holding member 6 and the developing sleeve 1 are each driven by a gear (not shown). Also, the first
In the figure, reference numeral 9 indicates a bias source for forming an alternating electric field between the developing sleeve 1 and the latent image holding member 6;
Alternating voltages such as alternating current with superimposed direct current, distorted wave alternating current, rectangular wave, and pulse wave are supplied, and the value is 1 from peak to peak.
000-2000V is suitable.

In FIG. 2, a latent image holding layer 6-2 made of a photosensitive layer or an insulating layer is coated or pasted on the surface of the latent image holding member 6 at a position corresponding to the central image area. This latent image holding layer 6
-2 varies from maximum ■9 to minimum ■1 depending on the latent image formed.
It has a surface potential of up to . On the other hand, latent image holding part 6
The substrate 6-1 is usually made of a conductive material, and its surface potential is at ground potential.

By the way, is there a bias towards the micro gap β in the past? When the i2 pressure is applied, the toner coated in the previous layer on the developing sleeve 1 flies between the sleeve and the drum, and a latent image is developed according to the surface potential of the latent image holding member 6. During this flight,
A very small portion of the toner separates from the developing section A due to gravity, laminar flow due to the rotation of the latent image holding member 6, etc., and does not adhere to the latent image holding member 6 or the developing sleeve 1, becoming scattered toner and forming an image. The inside of the forming device 4 may be contaminated. If this scattered toner adheres to the optical equipment system or the charging equipment system, the latent image holding member 6
The surface potential on the image was disturbed, and white streaks, black streaks, black dots, etc. were sometimes produced on the image. Further, there is a drawback that when the scattered toner falls onto the copy paper conveyance path, the copy paper becomes dirty.

An object of the present invention is to prevent contamination of the optical system, charging system, and conveyance system by preventing scattering of developer from the developing section in the conventional example described above, and to form stable images over a long period of time.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 3 d1 is a schematic diagram of an image forming apparatus according to the present invention.

This example is an example in which non-magnetic toner is used to improve color reproducibility. As an example of a developing method for non-magnetic toner, the developing method described in Japanese Patent Application No. 57-212320, which was previously proposed by the present applicant, can be applied.

This will be explained below using an example of the above application. In FIG. 3, 1 is an electrophotographic photosensitive drum, which holds a latent image formed by a latent image forming means (not shown) and rotates at the developing position shown in the direction of the arrow. pass through. For this photosensitive drum 1, T! 7. , a non-magnetic sleeve 2, which is a developer holding member that holds the F9 agent, is opposed to each other with a predetermined gap therebetween, and this sleeve 2 rotates in the direction of arrow a. A non-magnetic developer 4 is placed in the upper part of this sleeve 2.
A container 3 made of a non-magnetic material such as resin or aluminum is located to store a mixture of magnetic particles 5 and magnetic particles 5, and a magnetic blade 6 is screwed to the downstream side of the container 3 in the rotational direction of the sleeve.

On the other hand, a magnet 7 is provided on the opposite side of the sleeve 2 to the magnetic blade 6.

In the above configuration, the magnetic particles 5 in the container 3 form a magnetic brush 8 due to the magnetic field generated between the S pole of the magnet 7 and the magnetic blade 6. Then, as the sleeve 2 rotates, while holding the magnetic brush 8, the magnetic particles and the non-magnetic developer are mixed at 1:j:! .

Stir and mix. In this state, on the magnetic/sexual side of the container 3, due to the presence of this blade 6, the non-Hiq current 9
The mixture of the agent 14 and the magnetic particles 15 is prevented from moving by this blade, rises, and circulates in the direction of arrow C.

Due to this K, the non-magnetic developer is triboelectrically charged by the sleeve 2 or the magnetic particles. The charged developer is uniformly and thinly applied to the surface of the sleeve 2 by mirror force, and reaches a position facing the photoreceptor drum.

Next, the non-magnetic toner on the sleeve is transferred onto the photoreceptor drum according to the potential of the latent image on the photoreceptor drum, and development is performed. In this developing process, since an AC voltage is applied from the power supply 9 to the IJ-bu as a developing bias,
The non-magnetic toner forms a cloud in the developing section. In this development area, the cloud-shaped toner is washed away by the flow of wind in the development area caused by the rotation of the photosensitive drum and the rotation of the sleeve.

To prevent toner from scattering inside the machine due to this wind flow,
As shown in FIG. 3, an eaves 19 is provided near the drum so as to block the airflow d forming the drum at the bottom of the developing device, and the airflow d is directed to a hole 21 provided with a filter 20. The filter 20 traps toner contained in the wind, and prevents the toner from scattering into the machine.

In order to improve the filter effect, the openings of the filter 20 on the side facing the drum are made coarser, and the openings are gradually made smaller to eliminate the initial clogging caused by the side of the filter facing the drum. 2. As mentioned above, the present invention has been explained with reference to the embodiment using non-magnetic toner, but the developing method as shown in FIG. 1 using magnetic toner and the simultaneous two-component development Needless to say, the present invention can also be applied to the developing device 7k.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the developing unit of the image forming apparatus, FIG. 2 is an explanatory diagram showing a method for positioning the developer carrier and the latent image holding member, and FIG. 3 is the developing unit of the image forming apparatus according to the present invention. FIG. In the figure, the a developing bias power supply, 11, is! 1; 5 optical drum, 12 developing sleeve, 14 non-? i"! (・
1 toner, 16 a blade, 17 a magnet, 19 a canopy, 20 a filter, and 21 a hole. Applicant: Canon Co., Ltd. No. 7 Shoes

Claims (1)

[Claims] In an image forming apparatus in which a developing device is arranged opposite to a latent image holding member, the developing agent scattered from the developing device is collected on a filter member by deflecting the wind generated by the movement of the latent image holding member. Features of the image forming device.