JPS58162970A - Electrostatic image developing device - Google Patents

Abstract

PURPOSE:To reduce gamma characteristics, and to obtain a recorded image good in gradation, by adding to the first toner the second toner same in color, lower in color density, and small in electrical resistance. CONSTITUTION:As the first toner 13a, a toner having about 10<10>ohm.cm resistivity, and about 1.8 black density is used. As the second toner 13b, a toner having about 10<10>ohm.cm and about 1.0 black density (gray) is used. When the first and second toners are used in 4:1 ratio, the developing density characteristics (a) of the first toner 13a changes very little, but that of the second toner 13b lowers as shown by (b') and the saturation density is lowered to 1/5 of the case of being used alone. The density of a recorded copy image obtained by synthesis of these characteristics becomes as shown by a curve (b) in the graph, and a recorded image good in gradation is obtained.

Description

[Detailed description of the invention] - The present invention is 11! Regarding electrophotographic development, especially in electrophotographic technology 4, photoconductive i! The present invention relates to an electrostatic image developing device suitable for developing an electrostatic image formed on a solder medium.

Copying machines and laser beam printers that use electrophotographic technology first print the 111th side of a photoconductive recording medium by 411#.
After t, the front surface of the photoconductive recording medium is exposed to light in an amount corresponding to the density (brightness and darkness) of the image to be arranged to eliminate the m-plane charge and to transfer the charge in the direction of the photoconductive recording medium. Forms an electrostatic image with shading. Thereafter, toner is applied to the 11 sides of the photoconductive recording medium according to the amount of charge remaining thereon to form an electrostatic image of 3J. In these five electrophotographic techniques,
Since the electrical resistance of a photoconductive recording medium does not change linearly depending on the amount of exposure, and the amount of toner adhering also does not change directly depending on the amount of electricity, it is possible to record with good tonality. I couldn't resist it. .

Using a copying machine that utilizes electrophotographic technology as an example, we will explain the reasons why it is not possible to obtain a copy with good quality.

No. 1e7IJ is a schematic configuration diagram of a copying machine, in which a photoconductive layer is provided on both outer peripheral surfaces of a recording drum 1, and this recording drum 1 is rotated in the direction of arrow B). A charger 2 using corona discharge uniformly charges the surface of the photoconductive layer of the recording drum 1. Exposure lamp 3 is #! of recording drum 1. The image surface of the document 4 moving in the direction of the arrow (b) in synchronization with the speed of movement of the surface is illuminated, and the reflected light passes through the lenses 7 and 5 and the lens 7. The surface is irradiated.
The photoconductive layer is exposed to light with a light intensity of 1. As a result, the electrical resistance changes and surface charges are released, so that an electrostatic charge is formed on the recording drum 10 due to the density of charges. j
J image bale #8 has a container 8b containing lll preparation 81 and a container 8b containing lll preparation 81, and this developer 81 in the direction of arrow H.
Iron layer [that l! 1lllikIaIIll Pushi 8
The soul * o - forming c is 1, and the surface of the recording drum l is ms by an electric pusher 8c to generate an electrostatic 4at.
Statue of a bridge. Kaede end 8 heat is a mixture of a magnetic carrier and a non-magnetic toner, or a one-component magnetic toner that is made by putting magnetic powder in the toner resin and integrating it into fine particles of IJ ~ 40 tones (1,415 *). Use alone.

In the case of the regular IA imaging method, the amount of toner adhering to the tl& surface of the recording drum 1 is directly proportional to the magnitude (*Ii potential height) K of the electric charge modulating on the surface of the recording drum 1.

The surface rIIK of the recording drum 1, on which the toner image has been formed by HC, is pressed against the surface RIIK of the recording drum 1, which moves in the arrow direction in synchronization with this moderate movement of **, and is electrostatically rotated 441610
A toner image is electrostatically deposited on the recording paper 9. The damaged toner image transferred to the writing paper 9 is fixed by heating etc.
Copy entry *i+in. After the toner transfer, the surface of the recording drum IF) is cleaned by a cleaning device 11 and residual toner is removed.

Erase run 7°12 uniformly exposes III of the recording drum 1 to erase residual static images, thereby implementing a series of electrophotographic techniques.

By the way, when a selenium photosensitive layer is used as the photoconductive layer on the surface of the recording drum l, the general I [ILJ& in military aircraft]
' 9 A 1 Nom plane +t 700M0OV It becomes charged to 5! -C'-4i1fiK by 1m. When the surface of the recording drum 1 uniformly charged in this manner is exposed to light reflected from the original 4, the electrical resistance of the leading conductive layer decreases in accordance with the amount of reflected light corresponding to the color 11kK, and the charge is released. The sIR potential of the recording drum 1 decreases due to charge release, but the decrease t? #Gender is M! Figure 3 of the four-dimensional chart shown in Figures (1) to (4) (i.e. m-th
If the density of one image of 5 to 7gm114 changes linearly as shown by the broken line of 1ll(ri), the reflected light amount characteristic of the original 4 becomes 2-(ri).On the other hand, the photoconductivity due to exposure Since the resistance change of the layer is not linear, the surface potential of the recording drum 1 is as shown in zgt.The area where there are many umbrellas of 4° decrease is the area that has been exposed to light reflected from the white part of one image. Then, the surface potential decreases by ts + 5ovtc, and the area exposed to the reflected light from the black S component remains at about Wi111t at the time of one field bud charge without releasing the charge. A toner image is formed by forming an electrostatic image with magnetic toner, and this toner image is viewed on a recorder and then electrodeposited. Figure 2 (4) K shows 5, IIe brass dot 1
It increases as the leakage potential increases, but it eventually saturates at the color density of toner electrons (approximately 1.8 to 2.0). The finally obtained composite army return image I11 degree is determined by these 1st round trout gold, and becomes the 211th m (shown by the solid line **). However, this characteristic is different from the manuscript 1 image in the low-rise station area. lll1
It becomes lower than III (dashed line) and in the high l11 degree region, the original @-
Since the image I is higher than 11 degrees, the rate of change of 1131 in the intermediate region is large (r-temperature), resulting in an image with poor gradation.

The purpose of the present invention is to provide an electrostatic image developing device that can reduce r41 properties and obtain recorded images with good #&1 properties.

In order to achieve this goal, this book uses color IIIfI1. as a developer. A first toner that has a high color density and a large electrical resistivity and is relatively difficult to adhere to an electrostatic image, and a second toner that has a low color density and a small electrical resistivity and is relatively easy to adhere to an electrostatic image. By using the mixture, the second toner compensates for the IIi & deficiency of the recorded image in the low potential area, suppresses the #I direct excess in the high potential area, and improves rI.
It is characterized by reducing the f# characteristic and thereby obtaining a recorded image with refreshing gradation.

In order to increase the density of the recorded image in the low potential area of the recording drum 1 in this type of developing device, it is necessary to reduce the electrical resistivity of the toner to make it easier for the toner to adhere to the electrostatic image. If this is done, the saturation in the high potential region will be accelerated, and this alone will not be enough to reduce the T4I property. On the other hand, the color SVC of the toner with a small electric resistivity (referred to as the second toner) is lowered, and the color SVC of the toner with a higher electric resistivity and higher color density (referred to as the first toner) is lowered.
When an electrostatic image is developed using a filler prepared by heating the toner (5), the density can be lowered in the low potential region by reducing the adhesion of the second toner. The second toner that acts on the third toner density in this way in the low potential area also has a low color density, so in the area where the image density is higher than the color density of the toner with 2, the stripe 1 will appear. It acts to suppress the increase in density caused by toner. Therefore, by appropriately determining the electric resistivity, color density, and heating ratio of the toner @1 and the second toner, the gradation characteristics of S-I can be improved by decreasing the r characteristic as shown in j13EK. You can make it better. In #3, the flkJI! of the recorded image when the first toner is used alone as the developer.豐性--Mato,--Mato is the first developer. This is a typical example of a recorded image when the second toner is warmed and used. Furthermore, since the density of a reproduced recorded image is a density variable determined by the amount of toner particles attached per unit area, when trying to obtain a low-density recorded image using toner with a high a degree, the unit leakage The amount of toner particles deposited per print must be reduced, and the surface of the image Ii1 becomes rough and lacks smoothness.

However, if this is recorded with toner of low density, it is possible to increase the amount of toner particles that adhere to the image.
1111ti is relatively smooth. jllF4 diagram
When only the first toner 131 with a high degree of roughness is used as a developer,
This is a case where a mixture of donor 13m and low concentration second toner 13b is used.

Hereinafter, an example of a case where a selenium photoreceptor is used as the photoconductive layer of the recording drum 1 and a mixture of two kinds of one-component magnetic toners as described above is used as the developer will be described.

Therefore, the surface potential 4I characteristic of the electrostatic image formed in the 11I direction of the recording dot 1 by exposure is the same as that of the prior art. The electrical resistivity a of the first toner 13 is about 10.
&-cxs with a black ay of approximately 1.8 is used. When only the toner 131 of this ill is used as the fA developer, the development performance #IJI41 corresponds to the set aK in Figure 115. On the other hand, as the second heavy toner 131b, a gray one having an electrical resistivity a of about 1011 countries and a black color density of about 1.0 is used. The Ill*-direct characteristic when only this second toner 13b is used as the Ill image agent is m in Fig. S.
- I feel angry. This first. When the second toner is mixed at a ratio of 4:10 to form a 1AfII agent, the current 1#aFIl characteristic of #E1 toner 131 hardly changes, whereas the development aw4I characteristic of the second toner 13b is b The saturation concentration is about 115 K when used alone.
Become.

The 11-degree copy record-1 obtained by combining these characteristics makes it possible to obtain a 9-degree trace record 1Iii image as shown in FIG. 3.

On the other hand, in order to obtain the desired characteristics when an electrostatic image is imaged using such a mixed fi4 image agent, JIllt II2
The mixing ratio of the toners 13m and 13b must be a predetermined value. However, this developer is consumed at a higher rate than the second toner 13b, so in order to maintain the mixing ratio at a predetermined value, it is necessary to use the first toner. It is necessary to measure the mixing ratio of the second toner 13''l-13b and replenish the second toner 13b based on the result of the needle 111#i!i.

Figure 6 is 1. FIG. 7 is an original diagram of a means for measuring the mixing ratio of second toners 13a and 13b. Two conductive plates 14 and 15 are placed facing each other at a predetermined interval, and a gold bullion agent 13 is interposed between them by a predetermined device, and a power source 16 is connected between the two conductive plates 14 and 15.
By connecting and measuring the current value with ammeter 17,
The combined resistance RJkW'1i11I is calculated from this current value. Then, the composite resistance ratio of the developer 13 at a predetermined heating ratio is memorized (set), and the composite resistance R becomes larger as more of the second toner 13b is consumed, so the composite resistance a to be measured is set. the second toner 13 to be equal to the value
1 in the developer. 2nd toner 13m
.

The 1 ratio of 13b is kept at a predetermined value.

When only 13 m of the first toner is interposed between the four conductive plates 14 and 15, the resistance value R is approximately 100 Mg@direct, and when only 1 mb of the second toner is interposed, the resistance R is 45 t [)
1. is approximately IKΩ. If the combined ratio of the first and second toners (-13a, 13bf) is X, then the combined resistance R is R=,=R(1-X)+RX 1 .

FIG. 7 is an 11th vertical sectional view of a developing device showing one embodiment of the present invention. The fi image chamber 418 is separated by a partition plate 19 into a section 118a which accommodates the toner 13 of the irradiance and a section 118a which accommodates the toner 13 and the section III.
The toner 13b is divided into sections tab. The second toner 13kl stored in Ward-111bK is 11ta! Accordingly, it is supplied to the mixing section at the bottom of section #1sa, and -
The first toner 131 and the second toner 1 are
3Nl1 is combined to form a 1st developing steel 1s, which is coated with conductive magnetic developer 2gK to form a magnetic brush 13c#.

Since the magnetic pusher is transferred to the direction indicated by the arrow (C) together with the hero image 22, at the exit of the 1 The electric AM roll 22 is grounded, and the conductive I! 24 in contact with the outer periphery of the magnetic brush 13C is connected to the outer periphery of the magnetic brush 13C through the ammeter 17 and the power source 16. The current needle 17 is connected to the magnetic pusher 13c by the developing action.
When the toner ratio of the second toner 13b inside becomes smaller than a set value, a signal to rotate the a-tater 20 is issued to replenish the second toner 13b.

In the above embodiments, the development@IB is performed by mixing two types of toner, but it is also possible to use a combination of two or more types of toner. In addition, this developing device is used not only in toner image transfer type copying machines, but also in
It can also be applied to copying machines, laser beam printers, etc., which fix toner images obtained by developing electrostatic images formed on storage media as they are.

As described above, according to the present invention, the first toner, which has high color density and high electrical resistivity and is relatively difficult to adhere to an electrostatic image, and the first toner, which has a low resistance per color and By heating and using the second toner, which has a low resistivity and is relatively easy to adhere to the electrostatic image, the second toner compensates for the lack of memory density in the low potential area and also improves the density in the high density area. By suppressing the excessive concentration at [floor 14! ! This has the effect of providing good memorized images.

[Brief explanation of drawings]

Figure 51111 is a schematic configuration diagram of a copying machine, and Figures 2 (1) to (
Suha is a four-dimensional chart showing the chronicity of electrophotography technology, No. 311
1 is a characteristic diagram illustrating the gradation change of the memory 1liS by the 1jilK of the present invention, FIG. 5 is a diagram of the surface state of an image, FIG. 5 is the development density II of the developing device of the present invention!II#Ikli111, FIG. It is a side view of a developing device showing one embodiment. 1... Memory dot ^, 13... Developer,
13m......Kurei toner, 1mb...
...Second toner, 13e...Magnetic brush,
14... Conductive plate, l... Electricity 17.
・・・・・・Current needle, 2o・・・・Interface. Sai 1 times no '742 Sai 3 O R Yuura and T4 figure an ji 3 *self special ) 噌 [Ura
-1-1-i&--1alJt -J
[-*7啄(3)

Claims (1)

[Scope of Claims] 1. In an electrostatic image developing device that develops an electrostatic image formed on the surface of a recording medium with a developer, the developing steel is used as the developing steel for the first toner and has the same color and a low color degree. An electrostatic image developing device characterized in that a second toner having a low electrical resistivity is mixed therein. 2. In the aS item 1 of the % allowance claim, the first toner t8S degree is 1.8. The secondary magnetic toner has an electric resistance of 109, and the second toner has a color resistivity of t1.0.
An electrostatic image developing device that uses magnetic toner with an electrical resistivity of 10 g. 3. According to claim 1 or 2, an electrostatic image developing device 34 characterized in that the mixing ratio of the second toner to the first toner is 4:1. In an electrostatic image developing device that develops an electrostatic image formed on a recording medium llrM with an llr steel, a second toner having the same color, low color density, and low electrical resistivity as the first toner is used.
A resistivity measuring means for measuring the electrical resistivity of this developer, and l14ia according to the result of the resistivity needle side.
An electrostatic 4J1 soul* device comprising: a toner replenishing means for replenishing the second toner into the toner. 5. In the fourth patent claim, the purpose of the resistivity measuring means is to measure the electrical resistivity of a magnetic pixel formed by a developer to form an electrostatic image. Silence IIE image developing device.