JPS6017468A - Developing device - Google Patents

Abstract

PURPOSE:To facilitate control of development density in accordance with change of developing conditions by enabling control of the speed of the developer to be fed to a developing region in accordance with developing conditions. CONSTITUTION:When original density changes or the potential of an electrostatic latent image changes due to other causes, developing conditions are also changed, and when its change amounts up to 20-30%, the rotation speed of a developing sleeve 2 is changed to change the speed of feed of a developer to a developing region, and thus, recorded image density can be maintained constant. The feed speed of the developer to the developing region can also be controlled by changing the rotation speed of a magnet 3 in the arrow direction. The relationship between the rotation speed (r.p.m.) of the magnet 3 in the X-axis and recorded image density in the Y-axis as shown in the graph is obtained by fixing the rotation speed of the sleeve 2 in the arrow direction to 65r.p.m. and changing the rotation speed of the magnet 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device for an electrostatic recording device such as an electrophotographic copying device.

[Prior art]

In the developing device of a conventional electrostatic recording device, when trying to obtain a preferable recorded image density by controlling the developing density in response to changes in developing conditions such as original density and electrostatic latent image potential, for example, the original 6° In order to keep the development density constant even when the electrostatic latent image potential becomes low, the voltage of the charging electrode that uniformly charges the surface of the image carrier to form an electrostatic latent image is increased. The potential can be increased, the DC bias voltage applied between the image carrier and the developing device can be lowered to prevent the background of the electrostatic latent image from being developed, or the developer can be made mainly of magnetic carrier particles and toner particles. In cases where a two-component detergent is used, this is accomplished by increasing the toner content in the developer. Then, in order to increase the density of the recorded image, by increasing the voltage of the charging electrode to increase the charging potential, or by lowering the bias voltage applied to the developing device, the toner spreads to the background of the electrostatic latent image. If the toner ratio in the developer is increased, this leads to the problem that in addition to fogging, the interior of the machine is also more likely to be soiled due to toner scattering.

[Purpose of the invention]

The present invention has been made in order to provide a developing device that does not cause the above-mentioned problems when controlling the developing density in response to changes in developing conditions. The present invention provides a developing device that can control the developer density without increasing the bias voltage, lowering the bias voltage, or increasing the toner ratio in the developer.

[Structure of the invention]

The present invention relates to a developing device that develops an electrostatic latent image in a developing area with a developer, which is characterized in that the developer transport speed to the developing area can be adjusted according to developing conditions.
By making it possible to adjust the developer transport speed of the developing device according to the developing conditions, clear recorded image density can be achieved without the risk of fogging or staining the inside of the machine. be.

In this respect, in the conventional developing device, the developing sleeve for conveying and holding the developer in the developing device and the rotation speed of the magnet provided in the developing sleeve, that is, the developing area of the developer determined by these. The speed of conveyance to the developer was set constant so as to obtain an appropriate development density based on the differences in the developer used and the device configuration depending on the species. That is,
Conventional developing devices adjust the developed density by manually or automatically changing the rotational speed of the developing sleeve and magnet as appropriate and changing the speed at which the developer is conveyed to the developing area, thereby achieving the desired recorded image density. However, the present invention was made based on the discovery that the recorded image density can be sufficiently adjusted by changing the developer transport speed.

〔Example〕

The present invention will be explained below using illustrated examples.

FIG. 1 is a schematic cross-sectional view showing an example of the developing device of the present invention. Similarly, FIG. 1 is a graph showing the relationship between the number of rotations of the magnet and the recorded image density.

In FIG. 1, numeral 1 rotates in the direction of the arrow, and an electrostatic latent image is formed on its surface by a known charging and exposure device (not shown) or an electrostatic latent image forming device using a multi-stylus electrode or an ion control electrode. 2 is a visual image sleeve made of a non-magnetic material such as aluminum, and 3 is provided inside the developing sleeve 2 and has a plurality of nitrogen atoms on its surface. A magnet body having S magnetic poles in the circumferential direction, and this developing sleeve 2 and magnet body 3
and constitute a developer transport carrier. The developing sleeve 2 and the magnet body 3 are rotatable, and the figure shows that the developing sleeve 2 rotates to the left and the magnet body 3 rotates to the right. Still, the N and S magnetic poles of the magnet body 3 are normally magnetized to a magnetic flux density of 500 to 1500 Gauss, and the magnetic force causes a layer of developer consisting of toner particles and carrier particles to adhere to the surface of the developing sleeve 20. A so-called magnetic brush is formed. This magnetic brush moves the developing sleeve 20 by the above-mentioned rotation of the developing sleeve 2 and the magnet body 3.
It moves in the same direction as the rotation and is transported to the developing area AK. Reference numeral 4 denotes one seat of the magnetic brush on the surface of the developing sleeve 2, a layer thickness regulating blade made of magnetic or non-magnetic material that regulates the image, and 5 removes the magnetic brush that has passed through the developing area A from above the developing sleeve 2. A cleaning blade, 6 a developer reservoir, 7 a stirring screw for stirring the developer in the developer reservoir to uniformly mix toner particles and carrier particles, and 8 a toner hopper for replenishing toner particles T. , 9 is the developer reservoir 6
A toner supply roller 10 having four parts on the surface of a reservoir onto which toner particles T are dropped applies an AC voltage, a pulsed voltage, or a superimposed voltage of these and a DC voltage to the developing sleeve 2 via a time-keeping resistor 11, This is a bias power source that generates an oscillating electric field in the developing area A between the image carrier 1 and the developing sleeve 2 by grounding the conductive substrate.

In this developing device, the electrostatic latent image forming layer of the image carrier 1 is a layer made of an organic photoconductor OPO, and its surface speed in the direction of the arrow is 120 mm/sea, and the gap between the image carrier 1 and the developing sleeve 2, that is, Gap in development area A is 7508m1
Layer thickness regulating blade 4 and developing sleeve 2 made of non-magnetic material
The gap is 3508 m1, the magnetic flux density is 900 Gauss, the rotation speed of the magnet body 3 having 8 N and S magnetic poles at equal intervals in the direction of the arrow ' is 700 r - p 6 m 0, the weight average particle size of the developer DK is about 30 μm, and the resin is A two-component developer (minolta EP 310 developer) consisting of an insulating magnetic carrier with a specific resistance of about 1 x 10 Ωf and containing magnetic powder dispersed therein, and an insulating non-magnetic toner with an average particle size of 13 μm. agent),
Bias 11 Σ source 10 is applied to the developing sleeve 2 with an outer diameter of 30 mm.
A superimposed voltage of a DC voltage of 50 V and an AC voltage of 500 V, 1 kHz is applied to the developing sleeve 2 under conditions such that the oscillating field becomes an alternating electric field.
The electrostatic latent image is developed by changing the rotation speed in the direction of the arrow, transferred to recording paper by a transfer device (not shown), and fixed by a fixing device.The density of the recorded image is determined by the rotation speed of the developing sleeve 2. Along with the change, it changes as shown in FIG. Under these conditions, the magnetic brush formed on the developing sleeve 2 does not rub the surface of the image carrier 10, and the toner is transferred from the magnetic blank to the electrostatic latent image of the image 11 in the developing area A. It is done by flying to. 1, V8D in FIG. 2 is a negative electrostatic latent image potential with an absolute value of 150 cm or more formed on the image carrier 1 by changing the density of the original, and a DC voltage component of -150 V applied to the developing sleeve 2. It shows the absolute value of the difference between

As is clear from the results in Figure 2, if there is a change in the development conditions such as a change in the density of the original or a change in the electrification of the electrostatic latent image due to other causes, this change will cause a change in the potential of the electrostatic latent image. If it is within the range of 20-30% or less, use the developing sleeve 2.
By changing the rotation speed of the developer and changing the conveyance speed of the developer to the developing area A, it is possible to sufficiently maintain the recorded image density at a constant level. There is little fear.

The conveying speed of the developer to the developing area A can also be changed by changing the rotation speed of the magnet body 3 in the direction of the arrow. Rotate the developing sleeve 2 in the direction of the arrow to 65.
Developing was carried out under the same developing conditions as in FIG. 2, except that r, p, and m were fixed, and the rotation speed of the magnet body 3 in the direction of the arrow was changed. The rotation speed of the magnet body 3 and the recorded image density were Figure 3 shows the relationship.

As is clear from the results shown in Figure 3, by changing the rotation speed of the magnet body 3 to change the conveyance speed of the developer to the developing area A, the development conditions can be improved even more than by changing the rotation speed of the developing sleeve 20. The recorded image density can be maintained constant in response to large changes.

Of course, both the rotational speed of the developing sleeve 2 and the rotational speed of the magnet body 3 may be changed to correspond to changes in the developing conditions, thereby making it possible to cope with even larger changes. I cut it:! , 1. '.

The number of revolutions of the image sleeve 2 and the magnet 30 can be changed in response to changes in document density, etc. by forming, for example, an electrostatic latent image of a standard density strip on the image carrier 1, and automatically using the potential information or development density information. It may be possible to perform a switching operation in a manner similar to UIII, or it may be performed by an operator of the printing apparatus performing a switching operation based on the recorded image density.

As described above, in order to easily change the rotation speed of the developing sleeve 2 and the magnet 30, rather than using mechanical switching means such as a clutch, the developing sleeve 2 and the magnet 3 can be directly connected to the rotation control motor. It is preferable to electrically control the rotational speed of the motor by connecting the two motors, as this allows fine control of the rotational speed.

Development of the present invention in which the conveyance speed of developer to the development area is changed to correspond to changes in development conditions.
J:, In the developing device described above, the developer is conveyed to the developing area by a developer conveying carrier consisting of a combination of a relatively rotatable developing sleeve and a magnet, and a two-component developer is added to the developer. Preferably, the developing device is such that the magnetic brush formed on the developing sleeve by the developer does not come into close contact with the surface of the image carrier, and that an oscillating electric field is formed in the developing area. However, the present invention is not limited thereto; for example, a one-component developer made of magnetic toner particles may be used, a magnetic brush may be used to rub the image bearing surface, or an oscillating electric field may be used in the developing area. may not be formed.・In addition, for those in which the magnetic brush is kept out of contact with the image carrier,
A control electrode that does not prevent the toner particles from flying may be provided in the gap between the magnetic brush and the image carrier, and a voltage applied to the control electrode may form an oscillating electric field in the developing area.

〔Effect of the invention〕

In the developing device of the present invention, the developer supply speed is changed by changing the rotational speed of the developing sleeve and the magnet, which were conventionally fixed, so that the developer density can be varied and adjusted. It has now become possible to obtain recorded images with excellent clarity without causing fogging or internal stains that were seen in the development density adjustment in conventional developing devices. In particular, in a developing device that forms an oscillating electric field in the developing area without bringing the magnetic brush into contact with the surface of the image carrier, changes in developer supply speed as shown in FIG. 2, and especially in FIG. It is easy to glaze because the developing density changes greatly and smoothly depending on the amount of water, and it is easy to glaze the toner image if the photoreceptor is damaged or the magnetic brush adheres to the image carrier as in a developing device that develops by contacting a magnetic brush. This has the effect that there is no risk of the developed density becoming thinner due to scraping off. Further, in this case, if the developer is a two-component developer containing insulating carrier particles (weight average particle size of about 40 μm or less), even better recorded images can be obtained.
Highly preferred.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an example of the developing device of the present invention, and FIG.
This figure is a graph showing the relationship between the rotation speed of the developing sleeve and the recorded image density in the developing device of FIG. 1, and FIG. 3 is a graph showing the relationship between the rotation speed of the magnet body and the recorded image density. 1... Image carrier, 2... Developing sleeve, 3...
Magnet body, 4... Layer thickness regulating blade, 5... Cleaning blade, 6... Developer reservoir, 7... Stirring screw, 8...
... Toner hopper, 9 ... Toner supply roller, 1
0...Bias power supply, 11...Time keeping resistor, A...
Development area, D...developer, T...toner. Patent applicant: Roku Konishi Photo Industry Co., Ltd. Figure 1 β Figure 2 The rotation of the sword and the east three 7°' (

Claims (1)

[Scope of Claims] (1) A developing device that develops an electrostatic latent image in a developing area with a developer, characterized in that the developer transport speed to the developing area can be adjusted according to developing conditions. Device. (2) The developer is conveyed to the developing area by a developing sleeve having a magnet inside, and the developer conveying speed is adjusted by changing the rotation speed of the developing sleeve. Developing device according to item 1. (5) A patent claim in which the developer is conveyed to the developing area by a developing sleeve having a magnetic body inside, and the developer conveying speed is adjusted by changing the rotation speed of the magnetic body inside the developing sleeve. The developing device according to the range 1 or 2. (4) The developing device according to any one of claims 1 to 3, wherein an oscillating electric field is formed in the developing area. (5) The developing device according to any one of claims 2 to 4, wherein development is performed by the developer flying from the developing sleeve side and landing on the electrostatic latent image in the developing area. (6) The developing device according to any one of claims 1 to 5, wherein the developer is a two-component developer mainly consisting of magnetic carrier particles and toner particles.