JPS59195668A - Developing method - Google Patents

Abstract

PURPOSE:To obtain a developing method having high faithfulness and stable picture quality by limiting the range of total quantity of toner charge in a unit area on toner carrier. CONSTITUTION:The preferable range of the absolute value of toner charge quantity in a unit area on the carrier is 3X10<-10>C/cm<2>-10<+7>C/cm<2>. When the range is exceeded, fogging of a non-picture part or unsufficient development due to the increment of reflection force with the carrier is generated, so that various defects such as reduction of toner density or generation of ghost may be generated. For the toner weight in a unit area on the toner carrier, 0.1-20mg/cm<2> is preferable and 0.3-10mg/cm<2> is more proper. If the toner weight per unit area is small, i.e. when a toner layer is extremely thin, it may be impossible to obtain a picture of fine quality even if the quantity of charge is proper. When the toner weight is extremely large, i.e. when the toner layer is extremely thick, similar inclination can be recognized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing method used in electrophotography, electrostatic printing, etc., and particularly relates to a method for developing using -component system development.

Conventionally, various methods have been known for developing static latent images, such as magnetic brush development using a two-component developer mainly consisting of toner and carrier, cascade development, and liquid development. A good image is obtained. On the other hand, problems with developing methods using two-component developers include changes in image quality due to fluctuations in the mixing ratio of toner and carrier, deterioration of the carrier, toner scattering in dry developers, and liquid This includes dissipation of the carrier liquid in the developer. To solve these problems, various improvements have been made to the structure of the developing device, but they are expensive because they are equipped with a toner amount detection element, a toner and carrier agitator, etc. can not deny.

As a means to avoid these problems, a one-component developing system consisting only of toner has been devised in recent years. For example, an induced development method is known.

According to this method, conductive magnetic toner is attached to a sleeve containing a magnet, and a magnetic brush formed by the toner is brought into contact with an electrostatic latent image surface for development. That is,
Due to the conductivity of the toner, charges of opposite polarity to the latent image are induced in each toner through a magnetic brush facing the surface of the electrostatic latent image, and development is performed by electrical attraction. In such an induced development method, various problems of the two-component development method described above are solved, and a developing device can be constructed that is small, lightweight, and low in friction.

However, the induced development method can be applied to photosensitive paper coated with a photoconductor, such as zinc oxide photosensitive paper, and the process of electrically transferring it to plain paper or other transfer materials depends on the conductivity of the toner. Therefore, it is extremely difficult. In the induced development method, attempts have been made to increase the electrical resistance of the toner in order to improve the transferability, but in this case, the resistance of the toner is easily dependent on the environment such as humidity, and the quality of the developed image and the quality of the transferred image are affected. The reality is that it lacks stability.

- In view of the above-mentioned points of the component-based development system, the present applicant previously proposed a new development system in Japanese Patent Laid-Open Nos. 43027-1982 and 18656-1985. According to this developing method, since an insulating magnetic toner mainly composed of resin and magnetic powder is used, good copying can be performed even when applied to a copying machine having a transfer process. Furthermore, in the non-image area, this method
It has the advantage of sucking toner and preventing capri from coming out. Furthermore, since carrier particles are not used, there is no variation in the mixing ratio as described above, and there is no deterioration of the carrier particles, so it can be said that the electrostatic image developing method has high fidelity and stable image quality. However, since this method uses toner containing black magnetic powder, it has the drawback that it is extremely difficult to obtain clear chromatic color images.

The present invention was made in view of the above-mentioned circumstances, and its purpose is to provide a developing method with high fidelity and stable image quality. Furthermore, it is an object of the present invention to provide a developing method that eliminates the phenomenon of dryness and provides a high-resolution image that is uniform and has sufficient density in the image area.

Another object of the present invention is to provide a developing method that can use insulating non-magnetic color toner having a clear hue.

The feature is that in the method of developing an electrostatic image by placing an electrostatic image holder that holds an electrostatic image on its surface and a toner carrier that carries toner on its surface facing each other, The total charge amount of toner per unit area of is Q (coulomb/
-), the developing method satisfies 3xlO<IQl<10'.

The inventors of the present invention have extensively studied development methods using conventionally known non-magnetic toners, and have found that in order to obtain high-quality images using non-magnetic toners, it is necessary to use the magnetic force of conventional magnetic toners. It has been found that it is important to more precisely control the amount of charge held by the non-magnetic toner on the toner carrier, especially in the development area, compared to the method of coating and developing using a toner carrier.

This means that most of the force required to properly support the non-magnetic toner on the toner carrier depends on the amount of charge the toner has. This seems to be a characteristic requirement for the method of supporting and developing by non-magnetic force.

Conventionally, the so-called blow-off method is known as a method for measuring the amount of charge of toner, but this method measures the charging ability when sufficiently mixed with a fine magnetic carrier, and the developing method of the present invention. This method cannot be applied satisfactorily to cases in which single-component toner particles are stacked in many layers. As will be described later, the present inventors directly read the total charge amount of a single layer of toner per unit area on a carrier using the so-called suction type Faraday cage method, and used a completely different toner from conventional toners. The present invention was completed by obtaining information that is extremely useful for developing methods.

In the present invention, the preferred range of the absolute value of the toner charge amount per unit area on the carrier is 3 x 10" coulomb/-
~10 coulombs/-, but if this range is exceeded, fog will occur in non-image areas, or insufficient development will occur due to increased mirroring force with the carrier, resulting in uncountable problems such as a decrease in density or the generation of ghosts. Defects occur.

In the present invention, the weight of the toner per unit area on the toner carrier is preferably 0.1 to 20 cm/-, more preferably 3 to 10 cm/-. When the toner weight is small, that is, when the toner layer is extremely sparse or extremely thin, a good quality image tends not to be obtained even if the amount of charge is appropriate; That is, a similar tendency was observed when the toner layer was dense or extremely thick.

In the present invention, the charge amount of one layer of toner per unit area on the carrier and the weight of one layer of toner were determined using the so-called suction type Faraday cage method.

In this suction type Faraday cage method, the outer cylinder is pressed against the toner carrier to suck all the toner on a certain area on the carrier, and the toner is collected in a filter in the inner cylinder, and the increased weight of the filter is reduced by the toner carrier. The weight of one layer of toner per unit area above can be calculated. At the same time, this method allows the amount of charge per unit area on the toner carrier to be determined by measuring the amount of charge accumulated in an inner cylinder that is electrostatically shielded from the outside. (The suction Faraday cage method is described in, for example, the Electrophotographic Society Journal Vol. 1.11.
It has been introduced to Nα1 etc. ) In the present invention, the means for controlling the amount of toner charge on the toner carrier is not particularly limited. As will be described later, it is possible to control the toner charge amount by using various toner regulating means, and it goes without saying that the charge amount can also be changed depending on the type of toner used.

The present invention will be explained in detail below using figures and examples.

FIG. 1 is an explanatory diagram showing an example of an embodiment of an electrostatic latent image developing method using an insulating nonmagnetic toner. In the same figure, 1
is a cylindrical electrostatic image carrier, and an electrostatic latent image is formed on it by, for example, a known electrophotographic method such as the Carlson method or the NP method, and an insulating non-magnetic image is formed in the hopper 3, which is a toner supply means. The toner 5 is applied onto the toner carrier 2 by the application means 4 while regulating the layer thickness of the toner layer.
Develop it with The toner carrier 2 is a cylindrical developing roller made of stainless steel. The developing roller may be made of aluminum or other metals. Further, a metal roller coated with resin or the like may be used in order to triboelectrically charge the toner to a desired polarity. or,
The toner application means 4 may be a blade as shown in FIG. 1, or may be an elastic roller. When the application means 4 is an elastic roller, the amount of toner charge on the carrier can be changed by changing the pressing pressure of the elastic roller against the toner carrier. Further, an electrostatic image carrier 1 and a toner carrier 2
It is preferable to set the distance between the two layers to be at least the thickness of one layer of toner coated on the toner carrier 2. Furthermore, there is a bias power supply as shown in 6, and the electrostatic image carrier 1 and the toner carrier 2 are provided.
It is preferable that a developing bias be applied between.

FIG. 2 is an explanatory diagram of another example. In the figure, 1 is an electrostatic image carrier, 2 is a toner carrier, 5 is a toner, 3 is a hot spring (, 16 is a vibration member, 17 is a vibration generation means, 16a
1 is a permanent magnet, 19 is a cleaning blade, and 10 is a toner supply member.

That is, the vibrating member 16 is vibrated with an appropriate amplitude and frequency to form a uniform toner coating layer on the toner carrier 2 rotating at a constant speed, and the toner carrier 2 and the electrostatic image carrier 1 are The non-magnetic toner is made to face the electrostatic image with a gap larger than the thickness of the toner coating layer, and the non-magnetic toner is flown onto the electrostatic image to develop it. The vibration of the vibrating member 16 may be at any level as long as it does not cause liquid to flow directly onto the toner carrier 2. This is also possible by applying an AC and/or DC developing bias voltage between the toner carrier 2 and the electrostatic image holder 1.

FIG. 3 is an explanatory diagram of another example. In the same figure,
1 is an electrostatic image carrier, 2 is a toner carrier, 35 is an application roller, 36 is a fiber brush fixed to the surface thereof, 6 is a developing bias power source, 38 is a developing device, 9 is a toner cleaning blowing member, 40 indicates the coating bias source.

That is, toner No. 5 is uniformly applied onto the toner carrier 2 by rotating an application roller 35 and conveyed by a brush No. 36, and is then flown onto the electrostatic image No. 1 to be developed. The gap between the toner carrier 2 and the application roller 35 may be adjusted so as to form a uniform layer of toner on the toner carrier 2, and a bias voltage indicated by 40 may be applied to uniformly apply the toner. The gap between the electrostatic image carrier 1 and the toner carrier 2 may be made larger than the thickness of the toner layer, and a developing bias of 6 may be applied during development.

FIG. 4 is an explanatory diagram of another example. In the same figure, 1
2 is an electrostatic image carrier, 2 is a toner carrier, 43 is a developing device,
5 is a one-component non-magnetic toner, 6 is a bias power supply, 48 is a magnetic roller, 49 is a non-magnetic sleeve, 50 is a magnet, 52
Reference numeral 53 indicates a magnetic brush, and 53 indicates a single-component non-magnetic toner or a two-component developer in which a non-magnetic toner and a magnetic carrier are mixed.

That is, by holding the magnetic carrier on the non-magnetic sleeve 49 with magnetic force to form a brush, and rotating the 49,
A uniform layer of toner is formed by drawing up the toner or developer with the carrier brush and contacting and coating it on the second toner carrier. At this time, since the carrier is held on the toner carrier 48 by magnetic force, it does not move onto the toner carrier 2. Next, the non-magnetic toner is transferred to the toner carrier 2.
The image is transferred from above onto the electrostatic image carrier l and developed. The gap between the toner carrier 2 and the electrostatic image carrier 1 may be made larger than the thickness of the toner, and a developing bias voltage may be applied between the toner carrier 2 and the electrostatic image carrier 1.

FIG. 5 is an explanatory diagram of another example. In the same figure, 1
is an electrostatic image carrier, 2 is a toner carrier, 3 is a hopper, 5
2 is a magnetic brush made of a carrier toner mixture, 58 is a toner thickness regulating blade, 50 is a fixed magnet, 6 is a developing bias, and 5 is a one-component non-magnetic toner.

That is, the magnetic brush 52 formed on the toner carrier 2 is circulated by rotating the toner carrier 2, and the toner in the hopper 3 is poured in to coat the toner 2 in a uniform thin layer. Next, the toner carrier 2 and the electrostatic image carrier 1 are opposed to each other with a gap greater than the thickness of one toner layer, and the one-component nonmagnetic toner 5 on the toner carrier 2 is developed by flying onto the electrostatic image on the electrostatic image carrier 1.

The total amount of charge in one layer of toner can be controlled by the size of the magnetic brush 52, that is, the amount of carrier, and the regulating blade 58. The gap between 1 and 2 may be made larger than the thickness of the toner layer, and a developing bias of 6 may be applied.

Next, several kinds of insulating non-magnetic toners having a size of 5 to 20 microns as shown below were prepared.

Toner C: A positive toner made of a styrene resin, an aminoacrylic resin, and an azo red pigment.Toner C: A positive toner made of a styrene resin, a nigrosine dye, and a phthalocyanine pigment.Toner C: Styrene, lf fat,! : Positive toner consisting of phthalocyanine pigment Toner D: Negative toner consisting of polyester resin, metal chelate of alkylsalicylic acid, and phthalocyanine pigment Toner E: Low molecular weight polyethylene wax, rough-in-wax, and phthalocyanine pigment, on the surface Positive toner having styrene-dimethylaminoethyl methacrylate resin coating layer [Example-1] 100 parts by weight of zinc oxide, 20 parts by weight of styrene-butadiene copolymer, 40 parts by weight of n-butyl methacrylate,
A mixture consisting of 120 parts by weight of toluene and 4 parts by weight of Rose Bengal 1-thimethanol solution was dispersed and mixed in a ball mill for 6 hours.

This was applied to a 0.05 m thick aluminum plate using a wire bar so that the dry coating thickness was 40 μm, and the solvent was evaporated with hot air to produce a zinc oxide binder type photoreceptor in the form of a drum. This photoreceptor was subjected to -6 KV corona discharge to uniformly charge the entire surface, and then an original image was irradiated to form an electrostatic latent image.

Next, put toner A into a developing device as shown in Figure 1,
The electrostatic latent image was developed. At this time, the toner carrier was a stainless steel cylindrical sleeve with an outer diameter of 50 wn, the distance between the photosensitive drum surface and the sleeve surface was set to 250 μ, and an alternating current of 400 Hz, 1000 V, and a direct current bias of −150 V were applied to the sleeve. At this time, the amount of charge of the toner per unit area on the toner carrier is 9.2×10 (coulomb/
-), the weight of toner per unit area is 0.9 x 1
It was 0 (g/lyA). Next, the powder image was transferred while irradiating a direct current corona of 17 KV from the back side of the transfer paper to obtain a copied image. Fixing was performed using a commercially available plain paper copying machine. The obtained red image had uniform density and sufficient high resolution.

[Example 2] The same procedure as in Example 1 was carried out except that the toner applying means 4 of the developing device in Example 1 was changed from the blade to an elastic roller. At this time, the charge amount of one layer of toner per unit area on the toner carrier is 7.3 x 10 coulombs/-the weight of one layer of toner per unit area is 0.5 x 10 g/d, and the resulting red image As in Example-1, the image was of high quality.

[Example 3] Example 2 was carried out in the same manner as in Example 2 except that toner A in Example IK was replaced with toner B.

At this time, the charge amount of one layer of toner per unit area on the toner carrier was 4.5×10 coulombs/d1, and the weight of one layer of toner was 1.3×lOg/−. The obtained blue image was as good as in Example-1.

[Example-4] Example-1 was carried out in the same manner as in Example-1 except that toner A in Example-IK was replaced with toner C.

At this time, the charge amount of one layer of toner per unit area on the toner carrier was 5.5 x 10 coulombs/-, and the weight of one layer of toner was 1.8 x 10 g/-. The obtained blue image was as good as in Example-1.

[Example-5] The same process as in Example-1 was carried out except that the developing device in Example-1 was changed to an external developing device as shown in FIG. At this time, the vibrating member 16 is vibrated at a frequency of approximately 50 Hz and an amplitude of 0.2 m to form a uniform layer of toner on the toner carrier 2, with a gap of approximately 200 μ between the toner carrier 2 and the electrostatic image holder 1. toner carrier 2 with a frequency number of 10.
0 to several kilohertz, negative peak value -600 to -12
Development was performed by applying a bias AC electric field of 00 V and a plus peak value of +400 to +800 V. The charge amount of one toner layer per unit area on the toner carrier is 3 x 10 coulombs/ca+, the weight of one toner layer is 0.3 x 10 g/d, and the obtained red image is of good quality. there were.

[Example-6] The same procedure as in Example-1 was carried out except that the developing device in Example-1 was changed to a developing device as shown in FIG. At this time, a uniform layer of toner was formed on the toner carrier 2 by setting the gap between the toner carrier 2 and the application roller 35 to about 2 wm, and the length of the fiber brush 36 to about 3 Its. The charge amount of one layer of toner per unit surface Mt on the toner carrier is 2.
OX 10-'Coulomb/-, Tona's weight &''12
．． The resulting red image was of good quality with s x 10 gloA.

[Example 7] The same process as in Example 1 was carried out except that the developing device in Example 1 was changed to a developing device as shown in FIG. At this time, the gap between the toner carrier 2 and the magnetic roller 48 is approximately 2FI.
II+, the maximum thickness of the magnetic brush 52 made of a mixture of toner C and iron powder carrier (about 50μ on average) is about 6.
A uniform layer of toner was formed on the toner carrier 2. The amount of charge in one layer of toner per unit area is 6.8×1
0 coulomb/-, the weight of one layer of toner is 7 X l o'g
/-Ashi, frequency number K) tz, minus peak value -6
00~-1200V and plus peak value +400~+6
The blue image obtained by applying a bias of oov was a high-resolution image.

[Example-8] 20 g of the toner A of Example-1 and 20 g of the iron powder carrier were thoroughly mixed, and the mixture was mixed into a fifth plate in which the gap between the regulating blade 58 and the toner carrier 2 was set to be about 100 μ.
It was applied to the developing device shown in the figure. At this time, the charge amount of one layer of toner per unit area on the toner carrier is 1.4 x 10-8 coulombs/-, and the weight of one layer of toner is 1.1 x 10 g.
/i.

The gap between the toner carrier 2 and the electrostatic image carrier was maintained at about 300μ, and the frequency of the developing bias was several KHz.

The red image obtained by applying a bias of minus peak value -600 to -120 (IV and plus peak value +400 to -) -800V was of good quality.

Example The same procedure as Example 8 was carried out except that the transfer voltage was changed to +7 KV. The charge amount of one layer of toner of 9 per unit area on the toner carrier is 2. The weight of the toner layer was 4 x 10 g/-. The blue image obtained was of good quality.

[Example 10] The same procedure as Example 7 was carried out except that toner E was used. The charge amount of one layer of toner per unit area is 6.6 x 10 coulombs/aA1 The weight of one layer of toner is 1, l x 10 g/-
d, frequency number KHz, minus peak value -1000
~-1400V and plus peak value +200~+60
The blue image obtained by applying a bias of 0■ was a high-resolution image.

[Brief explanation of the drawing]

1 to 5 are explanatory views showing examples of embodiments of a developing method using insulating nonmagnetic toner. 1... Electrostatic image holder. 2... Toner carrier. 4.°・°° application means. 5... Toner. 6
...Bias power supply.

Claims (3)

[Claims] (1) In a method of developing an electrostatic image by opposing an electrostatic image carrier that holds an electrostatic image on its surface and a toner carrier that carries toner on its surface, A developing method characterized in that 3X10<IQ+<10-7, where the total charge amount of the toner is Q (coulomb/-). (2) The developing method according to claim 1, wherein the weight of one layer of toner per unit area on the toner carrier is 0.1 to 20 (my/crA). (3) Claim 2 in which the toner is a non-magnetic toner
Development method described in section.