A developer for developing electrostatic images, comprising a non-magnetic toner, the toner containing 17-60% by number of non-magnetic toner particles of 5 microns or smaller, containing 1-30% by number of non-magnetic toner particles of 8-12.7 microns, and containing 2.0% by volume or less of nonmagnetic toner particles of 16 microns or larger; wherein the non-magnetic toner has a volume-average particle size of 4-10 microns, and the non-magnetic toner particles of 5 microns or smaller have a particle size distribution satisfying the following formula: EQU N/V=-0.04N+k, wherein N denotes % by number of non-magnetic toner particles of 5 microns of smaller, V denotes % by volume of non-magnetic toner particles of 5 microns or smaller k denotes a positive number of 4.5-6.5, and N denotes a positive number of 17-60.

FIELD OF THE INVENTION AND RELATED ART 
The present invention relates to a non-magnetic toner for a one-component 
or two-component developer used for developing an electrostatic latent 
image in image forming methods such as electrophotography and 
electrostatic recording. 
Recently, as image forming apparatus such as electrophotographic copying 
machines have widely been used, their uses have also extended in various 
ways, and higher image quality has been demanded. For example, when 
original images such as general documents and books are copied, it is 
demanded that even minute letters are reproduced extremely finely and 
faithfully without thickening or deformation, or interruption. However, in 
ordinary image forming apparatus such as copying machines for plain paper, 
when the latent image formed on a photosensitive member thereof comprises 
thin-line images having a width of 100 microns or below, the 
reproducibility in thin lines is generally poor and the clarity of line 
images is still insufficient. 
Particularly, in recent image forming apparatus such as electrophotographic 
printers using digital image signals, the resultant latent picture is 
formed by a gathering of dots with a constant potential, and the solid, 
half-tone and highlight portions of the picture can be expressed by 
varying densities of dots. However, in a state where the dots are not 
faithfully covered with toner particles and the toner particles protrude 
from the dots, there arises a problem that a gradational characteristic of 
a toner image corresponding to the dot density ratio of the black portion 
to the white portion in the digital latent image cannot be obtained. 
Further, when the resolution is intended to be enhanced by decreasing the 
dot size so as to enhance the image quality, the reproducibility becomes 
poorer with respect to the latent image comprising minute dots, whereby 
there tends to occur an image without sharpness having a low resolution 
and a poor gradational characteristic. 
On the other hand, in image forming apparatus such as electrophotographic 
copying machines, there sometimes occurs a phenomenon such that good image 
quality is obtained in an initial stage but it deteriorates as the copying 
or print-out operation is successively conducted. The reason for such 
phenomenon may be considered that only toner particles which contribute to 
the developing operation are consumed in advance as the copying or 
print-out operation is successively conducted, and toner particles having 
a poor developing characteristic accumulate and remain in the developing 
device of the image forming apparatus. 
Hitherto, there have been proposed some developers for the purpose of 
enhancing the image quality. For example, Japanese Laid-Open Patent 
Application (JP-A, KOKAI) No. 3244/1976 (corresponding to U.S. Pat. Nos. 
3942979, 3969251 and 4112024) has proposed a non-magnetic toner wherein 
the particle size distribution is regulated so as to improve the image 
quality. This toner comprises relatively coarse particles and particularly 
preferably comprises about 60% by number or more of toner particles having 
a particle size of 8-12 microns. However, according to our investigation, 
it is difficult for such particle size to provide uniform and dense 
cover-up of the toner particles to a latent image. Further, the 
above-mentioned toner has a characteristic such that it contains 30% by 
number or less (e.g., about 29% by number) of particles of 5 microns or 
smaller and 5% by number or less (e.g., about 5% by number) of particles 
of 20 microns or larger, and therefore it has a broad particle size 
distribution which tends to decrease the uniformity in the resultant 
image. In order to form a clear image by using such relatively coarse 
toner particles having a broad particle size distribution, it is necessary 
that the gaps between the toner particles are filled by thickly 
superposing the toner particles thereby to enhance the apparent image 
density. As a result, there arises a problem that the toner consumption 
necessarily increases in order to obtain a prescribed image density. 
Japanese Laid-Open Patent Application No. 72054/1979 (corresponding to U.S. 
Pat. No. 4284701) has proposed a non-magnetic toner having a sharper 
particle size distribution than the above-mentioned toner. In this toner, 
particles having an intermediate weight have a relatively large particle 
size of 8.5-11.0 microns, and there is still room for improvement as a 
toner for a high resolution. 
Japanese Laid-Open Patent Application No. 129437/1983 (corresponding to 
British Patent No. 2114310) has proposed a non-magnetic toner wherein the 
average particle size is 6-10 microns and the mode particle size is 5-8 
microns. However, this toner only contains particles of 5 microns or less 
in a small amount of 15% by number or below, and it tends to form an image 
without sharpness. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a non-magnetic toner which 
has solved the above-mentioned problems. 
Another object of the present invention is to provide a non-magnetic toner 
for a two-component developer which has an excellent thin-line 
reproducibility and gradational characteristic and is capable of providing 
a high image density. 
A further object of the present invention is to provide a non-magnetic 
toner for a two-component developer which shows little change in 
performances when used for a long period. 
A further object of the present invention is to provide a non-magnetic 
toner for a two-component developer which shows little change in 
performances even when environmental conditions change. 
A further object of the present invention is to provide a non-magnetic 
toner for a two-component developer which shows an excellent 
transferability. 
A further object of the present invention is to provide a non-magnetic 
toner for a two-component developer which is capable of providing a high 
image density by using a small consumption thereof. 
A still further object of the present invention is to provide a 
non-magnetic toner for a two-component developer which is capable of 
forming a toner image excellent in resolution, gradational characteristic, 
and thin-line reproducibility even when used in an image forming apparatus 
using a digital image signal. 
A further object of the present invention is to provide a non-magnetic 
toner for a one-component developer which has an excellent thin-line 
reproducibility and gradational characteristic and is capable of providing 
a high image density. 
A further object of the present invention is to provide a non-magnetic 
toner for a one-component developer which shows little change in 
performances when used in a long period. 
A further object of the present invention is to provide a non-magnetic 
toner for a one-component developer which shows little change in 
performances even when environmental conditions change. 
A further object of the present invention is to provide a non-magnetic 
toner for a one-component developer which shows an excellent 
transferability. 
A further object of the present invention is to provide a non-magnetic 
toner for a one-component developer which is capable of providing a high 
image density by using a small consumption thereof. 
A still further object of the present invention is to provide a 
non-magnetic toner for a one-component developer which is capable of 
forming a toner image excellent in resolution, gradational characteristic, 
and thin-line reproducibility even when used in an image forming apparatus 
using a digital image signal. 
According to our investigation, it has been found that toner particles 
having a particle size of 5 microns or smaller have a primary function of 
clearly reproducing the contour of a latent image and of attaining close 
and precise cover-up of the toner to the entire latent image portion. 
Particularly, in the case of an electrostatic latent image formed on a 
photosensitive member, the field intensity in the edge portion thereof as 
the contour is higher than that in the inner portion thereof because of 
the concentration of the electric lines of force, whereby the sharpness of 
the resultant image is determined by the quality of toner particles 
collected to this portion. According to our investigation, it has been 
found that the control of quantity and distribution state for toner 
particles of 5 microns or smaller is effective in solving the problem in 
image sharpness. 
The developer for developing electrostatic images according to the present 
invention is based on the above knowledge and comprises: a non-magnetic 
toner, the toner containing 17-60% by number of non-magnetic toner 
particles having a particle size of 5 microns or smaller, containing 1-30% 
by number of non-magnetic toner particles having a particle size of 8-12.7 
microns, and containing 2.0% by volume or less of non-magnetic toner 
particles having a particle size of 16 microns or larger; wherein the 
non-magnetic toner has a volume-average particle size of 4-10 microns, and 
the non-magnetic toner particles having a particle size of 5 microns or 
smaller have a particle size distribution satisfying the following 
formula: 
EQU N/V=-0.04N+k, 
wherein N denotes the percentage by number of non-magnetic toner particles 
having a particle size of 5 micron or smaller, V denotes the percentage by 
volume of non-magnetic toner particles having a particle size of 5 microns 
or smaller, k denotes a positive number of 4.5-6.5, and N denotes a 
positive number of 17-60. 
These and other objects, features and advantages of the present invention 
will become more apparent upon a consideration of the following 
description of the preferred embodiments of the present invention taken in 
conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
The non-magnetic toner according to the present invention having specific 
particle size distribution as described above can faithfully reproduce 
thin lines in a latent image formed on a photosensitive member, and is 
excellent in reproduction of dot latent images such as halftone dot and 
digital images, whereby it provides images excellent in gradation and 
resolution characteristics. Further, the toner according to the present 
invention can retain a high image quality even in the case of successive 
copying or print-out, and can effect good development by using a smaller 
consumption thereof as compared with the conventional non-magnetic toner, 
even in the case of high-density images. As a result, the non-magnetic 
toner of the present invention is excellent in economical characteristics 
and further has an advantage in miniaturization of the main body of a 
copying machine or printer. 
The term "non-magnetic toner" used in the present invention refers to a 
toner showing a saturation magnetization of 0-10 emu/g under an external 
magnetic field of 5,000 oersted (Oe). 
The reason for the above-mentioned effects of the non-magnetic toner of the 
present invention is not necessarily clear but may assumably be considered 
as follows. 
The non-magnetic toner of the present invention is first characterized in 
that it contains 17-60% by number of non-magnetic toner particles of 5 
microns or below. Conventionally, it has been considered that non-magnetic 
toner particles of 5 microns or below are required to be positively 
reduced because the control of their charge amount is difficult, they 
impair the fluidity of the non-magnetic toner, and they cause toner 
scattering to contaminate a machine, and cause fog in the resultant image. 
However, according to our investigation, it has been found that the 
non-magnetic toner particles of 5 microns or below are an essential 
component to form a high-quality image. 
For example, we have conducted the following experiment. 
Thus, there was formed on a photosensitive member a latent image wherein 
the surface potential on the photosensitive member was changed from a 
large developing potential contrast at which the latent image would easily 
be developed with a large number of toner particles, to a half-tone 
developing potential contrast, and further to a small developing potential 
contrast at which the latent image would be developed with only a small 
number of toner particles. 
Such latent image was developed with a one-component developer comprising a 
non-magnetic toner or a two-component developer comprising carrier 
particles and the non-magnetic toner having a particle size distribution 
ranging from 0.5 to 30 microns. Then, the toner particles attached to the 
photosensitive member were collected and the particle size distribution 
thereof was measured. As a result, it was found that there were many 
non-magnetic toner particles having a particle size of 8 microns or below, 
particularly 5 microns or below. Based on such finding, it was discovered 
that when non-magnetic toner particles of 5 microns or below were so 
controlled that they were smoothly supplied for the development of a 
latent image formed on a photosensitive member, there could be obtained an 
image truly excellent in reproducibility, and the toner particles were 
faithfully attached to the latent image without protruding therefrom. 
The non-magnetic toner of the present invention is secondly characterized 
in that it contains 1-30% by number (preferably 1-23% by number) of 
non-magnetic toner particles of 8-12.7 microns. Such second feature 
relates to the above-mentioned necessity for the presence of the toner 
particles of 5 microns or below. 
As described above, the toner particles having a particle size of 5 microns 
or below have the ability to strictly cover a latent image and to 
faithfully reproduce it. On the other hand, in the latent image per se, 
the field intensity in its peripheral edge portion is higher than that in 
its central portion. Therefore, toner particles sometimes cover the inner 
portion of the latent image in a smaller amount than that in the edge 
portion thereof, whereby the image density in the inner portion appears to 
be lower. Particularly, the non-magnetic toner particles of 5 microns or 
below strongly have such tendency. However, we have found that when 1-30% 
by number (preferably 1-23% by number) of toner particles of 8-12.7 
microns are contained in a toner, not only the above-mentioned problem can 
be solved but also the resultant image can be made clearer. 
According to our knowledge, the reason for such phenomenon may be 
considered that the toner particles of 8-12.7 microns have a charge amount 
suitably controlled in relation to those of 5 microns or below, and that 
these toner particles are supplied to the inner portion of the latent 
image having a lower field intensity than that of the edge portion thereby 
to compensate the decrease in cover-up of the toner particles to the inner 
portion as compared with that in the edge portion, and to form a uniform 
developed image. As a result, there may be provided a sharp image having a 
high-image density and excellent resolution and gradation characteristic. 
The third feature of the non-magnetic toner of the present invention is 
that toner particles having a particle size of 5 microns or smaller 
contained therein satisfy the following relation between their percentage 
by number (N) and percentage by volume (V): 
EQU N/V=-0.04N+k, 
wherein 4.5.ltoreq.k.ltoreq.6.5, and 17.ltoreq.N.ltoreq.60. 
The region satisfying such relationship is shown in FIG. 5 or 7. The 
non-magnetic toner according to the present invention which has the 
particle size distribution satisfying such region, in addition to the 
above-mentioned features, can attain excellent developing characteristic. 
According to our investigation on the state of the particle size 
distribution with respect to toner particles of 5 microns or below, we 
have found that there is a suitable state of the presence of fine powder 
in non-magnetic toner particles. More specifically, in the case of a 
certain value of N, it may be understood that a large value of N/V 
indicates that the particles of 5 microns or below (e.g., 2-4 microns) are 
significantly contained, and a small value of N/V indicates that the 
frequency of the presence of particles near 5 microns (e.g., 4-5 microns) 
is high and that of particles having a smaller particle size is low. When 
the value of N/V is in the range of 2.1-5.82, N is in the range of 17-60, 
and the relation represented by the above-mentioned formula is satisfied, 
good thin-line reproducibility and high resolution are attained. 
In the non-magnetic toner of the present invention, non-magnetic toner 
particles having a particle size of 16 microns or larger are contained in 
an amount of 2.0% by volume or below. The amount of these particles may 
preferably be as small as possible. 
As described hereinabove, the non-magnetic toner of the present invention 
has solved the problems encountered in the prior art from a viewpoint 
utterly different from that in the prior art, and can meet the recent 
severe demand for high image quality. 
Hereinbelow, the present invention will be described in more detail. 
In the present invention, the non-magnetic toner particles having a 
particle size of 5 microns or smaller are contained in an amount of 17-60% 
by number, preferably 25-50% by number, more preferably 30-50% by number, 
based on the total number of particles. If the amount of non-magnetic 
toner particles is smaller than 17% by number, the toner particles 
effective in enhancing image quality is insufficient. Particularly, as the 
toner particles are consumed in successive copying or print-out, the 
component of effective non-magnetic toner particles is decreased, and the 
balance in the particle size distribution of the non-magnetic toner shown 
by the present invention is deteriorated, whereby the image quality 
gradually decreases. On the other hand if, the above-mentioned amount 
exceeds 60% by number, the non-magnetic toner particles are liable to be 
mutually agglomerated to produce toner agglomerates having a size larger 
than the original particle size. As a result, roughened images are 
provided, the resolution is lowered, and the density difference between 
the edge and inner portions is increased, whereby an image having an inner 
portion with a low density is liable to occur. 
In the non-magnetic toner of the present invention, the amount of particles 
in the range of 8-12.7 microns is 1-30% by number, preferably 1-23% by 
number, more preferably 8-20% by number. If the above-mentioned amount is 
larger than 30% by number, not only the image quality deteriorates but 
also excess development (i.e., excess cover-up of toner particles) occurs, 
thereby to invite an increase in toner consumption. On the other hand if, 
the above-mentioned amount is smaller than 1% by number, it is difficult 
to obtain a high image density. 
In the present invention, the percentage by number (N %) and that by volume 
(V %) of non-magnetic toner particles having a particle size of 5 microns 
or below satisfy a relationship of N/V=-0.04 N+k, wherein k represents a 
positive number satisfying 4.5.ltoreq.k.ltoreq.6.5. The number k may 
preferably satisfy 4.5.ltoreq.k.ltoreq.6.0, more preferably 
4.5.ltoreq.k.ltoreq.5.5. Further, as described above, the percentage N 
satisfies 17.ltoreq.N.ltoreq.60, preferably 25.ltoreq.N.ltoreq.50, more 
preferably 30.ltoreq.N.ltoreq.50. 
If k&lt;4.5, non-magnetic toner particles of 5.0 microns or below are 
insufficient, and the resultant image density, resolution and sharpness 
decrease. When fine toner particles in a non-magnetic toner, which have 
conventionally been considered useless, are present in an appropriate 
amount, they attain closest packing of toner in development (i.e., in a 
latent image formed on a photosensitive drum) and contribute to the 
formation of a uniform image free of coarsening. Particularly, these 
particles fill thinline portions and contour portions of an image, thereby 
to visually improve the sharpness thereof. If k&lt;4.5 in the above formula, 
such component becomes insufficient in particle size distribution, whereby 
the above-mentioned characteristics become poor. 
Further, in view of the production process, a large amount of fine powder 
must be removed by classification in order to satisfy the condition of 
k&lt;4.5. Such process is disadvantageous in yield and toner costs. 
On the other hand, if k&gt;6.5, an excess of fine powder is present, whereby 
the resultant image density is liable to decrease in successive copying. 
The reason for such phenomenon may be considered that an excess of fine 
non-magnetic toner particles having an excess amount of charge are 
triboelectrically attached to a developing sleeve and prevent normal toner 
particles from being carried on the developing sleeve or carrier and being 
supplied with charge. 
In the magnetic toner of the present invention, the amount of non-magnetic 
toner particles having a particle size of 16 microns or larger may 
preferably be smaller than 2.0% by volume, more preferably 1.0% by volume 
or smaller, particularly preferably 0.5% by volume or smaller. 
If the above amount is larger than 2.0% by volume, these particles impair 
thin-line reproducibility. In addition, toner particles of 16 microns or 
larger are present as protrusions on the surface of the thin layer of 
toner particles formed on a photosensitive member by development, and they 
vary the transfer condition for the toner by irregulating the delicate 
contact state between the photosensitive member and a transfer paper (or a 
transfer-receiving material) by the medium of the toner layer. As a 
result, there occurs an image with transfer failure. 
In the present invention, the volume-average particle size of the toner is 
4-10 microns, preferably 4-9 microns, more preferably 4-8 microns. This 
value closely relates to the above-mentioned features of the non-magnetic 
toner according to the present invention. If the volume-average particle 
size is smaller than 4 microns, there tend to occur problems such that the 
amount of toner particles transferred to a transfer paper is insufficient 
and the image density is low, in the case of an image such as a graphic 
image wherein the ratio of the image portion area to the whole area is 
high. The reason for such phenomenon may be considered the same as in the 
above-mentioned case wherein the inner portion of a latent image provides 
a lower image density than that in the edge portion thereof. If the 
volume-average particle size exceeds 10 microns, the resultant resolution 
is not good and there tends to occur a phenomenon such that the image 
quality is lowered in successive use even when it is good in the initial 
stage thereof. 
Although the particle size distribution of a toner is measured by means of 
a Coulter counter in the present invention, it may also be measured in 
various ways. 
Coulter counter Model TA-II (available from Coulter Electronics Inc.) is 
used as an instrument for measurement, to which an interface (available 
from Nikkaki K.K.) for providing a number-basis distribution and a 
volume-basis distribution, and a personal computer CX-1 (available from 
Canon K.K.) are connected. 
For measurement, a 1%-NaCl aqueous solution as an electrolytic solution is 
prepared by using a reagent-grade sodium chloride. Into 100 to 150 ml of 
the electrolytic solution, 0.1 to 5 ml of a surfactant, preferably an 
alkylbenzenesulfonic acid salt, is added as a dispersant, and 2 to 20 mg 
of a sample is added thereto. The resultant dispersion of the sample in 
the electrolytic liquid is subjected to a dispersion treatment for about 
1-3 minutes by means of an ultrasonic disperser, and then subjected to 
measurement of particle size distribution in the range of 2-40 microns by 
using the above-mentioned Coulter counter Model TA-II with a 100 
micron-aperture to obtain a volume-basis distribution and a number-basis 
distribution. From the results of the volume-basis distribution and 
number-basis distribution, parameters characterizing the non-magnetic 
toner of the present invention may be obtained. 
The binder for use in constituting the toner according to the present 
invention, when applied to a hot pressure roller fixing apparatus using an 
oil applicator, may be a known binder resin for toners. Examples thereof 
may include: homopolymers of styrene and its derivatives, such as 
polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene 
copolymers, such as styrene-p-chlorostyrene copolymer, 
styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, 
styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-methyl 
.alpha.-chloromethacrylate copolymer, styrene-acrylonitrile copolymer, 
styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, 
styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, 
styrene-isoprene copolymer, and styrene-acrylonitrile-indene copolymer; 
polyvinyl chloride, phenolic resin, natural resin-modified phenolic resin, 
natural resin-modified maleic acid resin, acrylic resin, methacrylic 
resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, 
polyamide resin, furan resin, epoxy resin, xylene resin, polyvinylbutyral, 
terpene resin, coumarone-indene resin and petroleum resin. 
In a hot pressure roller fixing system using substantially no oil 
application, serious problems are occur because of an offset phenomenon, 
where that a part of toner image on a toner image-supporting member is 
transferred to a roller, and the intimate adhesion of a toner on the toner 
image-supporting member. As a toner fixable with less heat energy is 
generally liable to cause blocking or caking in storage or in a developing 
apparatus, this should be also taken into consideration. Accordingly, when 
a hot roller fixing system using almost no oil application is adopted in 
the present invention, selection of a binder resin becomes more important. 
A preferred binder resin may for example be a crosslinked styrene 
copolymer, or a crosslinked polyester. Examples of comonomers to form such 
a styrene copolymer may include one or more vinyl monomers selected from: 
monocarboxylic acid having a double bond and their substituted 
derivatives, such as acrylic acid, methyl acrylate, ethyl acrylate, butyl 
acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl 
acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl 
methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, and 
acrylamide; dicarboxylic acids having a double bond and their substituted 
derivatives, such as maleic acid, butyl maleate, methyl maleate, and 
dimethyl maleate; vinyl esters, such as vinyl chloride, vinyl acetate, and 
vinyl benzoate; ethylenic olefins, such as ethylene, propylene, and 
butylene; vinyl ketones, such as vinyl methyl ketone, and vinyl hexyl 
ketone; vinyl ethers, such as vinyl methyl ether, vinyl ethyl ether, and 
vinyl isobutyl ether. As the crosslinking agent, a compound having two or 
more polymerizable double bonds may principally be used. Examples thereof 
include: aromatic divinyl compounds, such as divinylbenzene, and 
divinylnaphthalene; carboxylic acid esters having two double bonds, such 
as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 
1,3-butanediol diacrylate; divinyl compounds such as divinyl aniline 
divinyl ether, divinyl sulfide and divinyl sulfone; and compounds having 
three or more vinyl groups. These compounds may be used singly or in 
mixture. In view of the fixability and anti-offset characteristic of the 
toner, the crosslinking agent may preferably be used in an amount of 
0.01-10 wt. %, preferably 0.05-5 wt. %, based on the weight of the binder 
resin. 
For a pressure-fixing system, a known binder resin for a pressure-fixable 
toner may be used. Examples thereof may include: polyethylene, 
polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl 
acrylate copolymer, ethylene-vinyl acetate copolymer, ionomer resin, 
styrene-butadiene copolymer, styrene-isoprene copolymer, linear saturated 
polyesters and paraffins. 
The non-magnetic toner according to the present invention may also 
preferably be used as a toner for full- or multi-color image formation. 
The color image formation process may for example be carried out by causing 
light rays from an original to be incident on a photoconductive layer of a 
photosensitive member through a color-separation transmission filter in a 
complementary color with a toner color to form an electrostatic latent 
image on the photoconductive layer. Then, the toner of the color is held 
on a support (material) such as plain paper through the developing and 
transfer steps. The above steps are repeated for toners of other colors 
several times in register with and superposition on the previous toner 
image on the same support, and the superposed toner images are subjected 
to a single fixing step to provide a final full-color image. 
For such purpose, color toners of yellow, magenta and cyan (additionally, a 
black toner as desired) may generally be used. 
When the non-magnetic toner according to the present invention is used as 
the toner for color image formation, there may be obtained a good color 
image excellent in color mixing characteristic and gloss characteristic. 
In such case, in view of the color mixing characteristic, the binder resin 
may preferably be a non-crosslinked polyester resin which shows a low 
viscosity at a fixing temperature. 
In the non-magnetic toner of the present invention, it is preferred that a 
charge controller may be incorporated in the toner particles (internal 
addition), or may be mixed with the toner particles (external addition). 
By using the charge controller, it is possible to most suitably control 
the charge amount corresponding to a developing system to be used. 
Particularly, in the present invention, it is possible to further 
stabilize the balance between the particle size distribution and the 
charge. As a result, when the charge controller is used in the present 
invention, it is possible to further clarify the above-mentioned 
functional separation and mutual compensation corresponding to the 
respective particle size ranges, in order to enhance the image quality. 
Examples of a positive charge controller may include; nigrosine and its 
modification products modified by a fatty acid metal salt; quaternary 
ammonium salts, such as 
tributylbenzyl-ammonium-1-hydroxy-4-naphthosulfonic acid salt, and 
tetrabutylammonium tetrafluoroborate; diorganotin oxides, such as 
dibutyltin oxide, dioctyltin oxide, and dicyclohexyltin oxide; and 
diorganotin borates, such as dibutyltin borate, dioctyltin borate, and 
dicyclohexyltin borate. These positive charge controllers may be used 
singly or as a mixture of two or more species. Among these, a 
nigrosine-type charge controller or a quaternary ammonium salt charge 
controller may particularly preferably be used. 
As another type of positive charge controller, there may be used a 
homopolymer of a monomer having an amino group represented by the formula: 
##STR1## 
wherein R.sub.1 represents H or CH.sub.3 ; and R.sub.2 and R.sub.3 each 
represent a substituted or unsubstituted alkyl group (preferably C.sub.1 
-C.sub.4); or a copolymer of the monomer having an amine group with 
another polymerizable monomer such as styrene, acrylates, and 
methacrylates as described above. In this case, the positive charge 
controller also has a function of (a part or the entirety of) a binder. 
On the other hand, a negative charge controller can be used in the present 
invention. Examples thereof may include an organic metal complex or a 
chelate compound. More specifically there may preferably be used aluminum 
acetyl-acetonate, iron (II) acetylacetonate, and a 3,5-di-tertiary 
butylsalicylic acid chromium. There may more preferably be used 
acetylacetone complexes (inclusive of monoalkyl- or dialkyl-substituted 
derivatives thereof), or salicylic acid-type metal salts or complexes 
(inclusive of monoalkyl- or dialkyl-substituted derivatives thereof). 
Among these, salicylic acid-type complexes or metal salts may particularly 
preferably be used. 
It is preferred that the above-mentioned charge controller (one not having 
a function of a binder) is used in the form of fine powder. In such case, 
the number-average particle size thereof may preferably be 4 microns or 
smaller, more preferably 3 microns or smaller. 
In the case of internal addition, such charge controller may preferably be 
used in an amount of 0.1-20 wt. parts, more preferably 0.2-10 wt. parts, 
per 100 wt. parts of a binder resin. 
It is preferred that silica fine powder is added to the non-magnetic toner 
of the present invention. 
In the non-magnetic toner of the present invention having the 
above-mentioned particle size distribution characteristic, the specific 
surface area thereof becomes larger than that in the conventioned toner. 
In a case where the non-magnetic toner particles are caused to contact the 
surface of a cylindrical electroconductive sleeve containing a magnetic 
field-generating means therein in order to triboelectrically charge them, 
the frequency of the contact between the toner particle surface and the 
sleeve is increased as compared with that in the conventional non-magnetic 
toner, whereby the abrasion of the toner particle and/or the contamination 
of the sleeve is liable to occur. However, when the non-magnetic toner of 
the present invention is combined with the silica fine powder, the silica 
fine powder is disposed between the toner particles and the carrier or 
sleeve surface, whereby the abrasion of the toner particle is remarkably 
reduced. 
Thus, the life of the non-magnetic toner and/or the sleeve may be 
lengthened and the chargeability may stably be retained. As a result, 
there can be provided a one-component developer, or a two-component 
developer comprising a non-magnetic toner and carrier, which shows 
excellent characteristics in long-time use. Further, the non-magnetic 
toner particles having a particle size of 5 microns or smaller, which play 
an important role in the present invention, may produce a better effect in 
the presence of the silica fine powder, thereby to stably provide 
high-quality images. 
The silica fine powder may be that produced through the dry process and the 
wet process. The silica fine powder produced through the dry process is 
preferred in view of the anti-filming characteristic and durability 
thereof. 
The dry process referred to herein is a process for producing silica fine 
powder through vapor-phase oxidation of a silicon halide. 
On the other hand, in order to produce silica powder to be used in the 
present invention through the wet process, various processes known 
heretofore may be applied. 
The silica powder to be used herein may be anhydrous silicon dioxide 
(colloidal silica), and also a silicate such as aluminum silicate, sodium 
silicate, potassium silicate, magnesium silicate and zinc silicate. 
Among the above-mentioned silica powders, those having a specific surface 
area as measured by the BET method with nitrogen adsorption of 30 m.sup.2 
/g or more, particularly 50-400 m.sup.2 /g, provides a good result. 
In the present invention, the silica fine powder may preferably be used in 
an amount of 0.01-8 wt. parts, more preferably 0.1-5 wt. parts, with 
respect to 100 wt. parts of the non-magnetic toner. 
In the case where the non-magnetic toner of the present invention is used 
as a positively chargeable non-magnetic toner, it is preferred to use 
positively chargeable fine silica powder rather than negatively chargeable 
fine silica powder, in order to prevent the abrasion of the toner particle 
and the contamination on the carrier or sleeve surface, and to retain the 
stability in chargeability. 
In order to obtain positively chargeable silica fine powder, the 
above-mentioned silica powder obtained through the dry or wet process may 
be treated with a silicone oil having an organic groups containing at 
least one nitrogen atom in its side chain, a nitrogen-containing silane 
coupling agent, or both of these. 
In the present invention, "positively chargeable silica" means one having a 
positive triboelectric charge with respect to an iron powder carrier when 
measured by the blow-off method. 
The silicone oil having a nitrogen atom in its side chain to be used in the 
treatment of silica fine powder may be a silicone oil having at least the 
following partial structure: 
##STR2## 
wherein R.sub.1 denotes hydrogen, alkyl, aryl or alkoxyl; R.sub.2 denotes 
alkylene or phenylene; R.sub.3 and R.sub.4 respectively denote hydrogen, 
alkyl, or aryl; and R.sub.5 denotes a nitrogen-containing heterocyclic 
group. 
The above alkyl, aryl, alkylene and phenylene group can contain an organic 
group having a nitrogen atom, or have a substituent such as halogen within 
an extent not impairing the chargeability. The above-mentioned silicone 
oil may preferably be used in an amount of 1-50 wt. %, more preferably 
5-30 wt. %, based on the weight of the silica fine powder. 
The nitrogen-containing silane coupling agent used in the present invention 
generally has a structure represented by the following formula: 
EQU R.sub.m --Si-Y.sub.n, 
wherein R is an alkoxy group or a halogen atom; Y is an amino group or an 
organic group having at least one amino group or nitrogen atom; and m and 
n are positive integers of 1-3 satisfying the relationship of m+n =4. 
The organic group having at least one nitrogen group may for example be an 
amino group having an organic group as a substituent, a 
nitrogen-containing heterocyclic group, or a group having a 
nitrogen-containing heterocyclic group. The nitrogen-containing 
heterocyclic group may be unsaturated or saturated and may respectively be 
known ones. Examples of the unsaturated heterocyclic ring structure 
providing the nitrogen-containing heterocyclic group may include the 
following: 
##STR3## 
Examples of the saturated heterocyclic ring structure include the 
following: 
##STR4## 
The heterocyclic groups used in the present invention may preferably be 
those of five-membered or six-membered rings in consideration of 
stability. 
Examples of the silane coupling agent include: 
aminopropyltrimethoxysilane, 
aminopropyltriethoxysilane, 
dimethylaminopropyltrimethoxysilane, 
diethylaminopropyltrimethoxysilane, 
dipropylaminopropyltrimethoxysilane, 
dibutylaminopropyltrimethoxysilane, 
monobutylaminopropyltrimethoxysilane, 
dioctylaminopropyltrimethoxysilane, 
dibutylaminopropyldimethoxysilane, 
dibutylaminopropylmonomethoxysilane, 
dimethylaminophenyltriethoxysilane, 
trimethoxysilyl-.gamma.-propylphenylamine, and 
trimethoxysilyl-.gamma.-propylbenzylamine. 
Further, examples of the nitrogen-containing 
heterocyclic compounds represented by the above 
structural formulas include: 
trimethoxysilyl-.gamma.-propylpiperidine, 
trimethoxysilyl-.gamma.-propylmorpholine, and 
trimethoxysilyl-.gamma.-propylimidazole. 
The above-mentioned nitrogen-containing silane coupling agent may 
preferably be used in an amount of 1-50 wt. %, more preferably 5-30 wt. %, 
based on the weight of the silica fine powder. 
The thus treated positively chargeable silica powder shows an effect when 
added in an amount of 0.01-8 wt. parts, and more preferably may be used in 
an amount of 0.1-5 wt. parts, respectively with respect to the positively 
chargeable non-magnetic toner to show a positive chargeability with 
excellent stability. As a preferred mode of addition, the treated silica 
powder in an amount of 0.1-3 wt. parts with respect to 100 wt. parts of 
the positively chargeable non-magnetic toner should preferably be in the 
form of being attached to the surface of the toner particles. The 
above-mentioned untreated silica fine powder may be used in the same 
amount as mentioned above. 
The silica fine powder used in the present invention may be treated as 
desired with another silane coupling agent or with an organic silicon 
compound for the purpose of enhancing hydrophobicity. The silica powder 
may be treated with such agents in a known manner so that they react with 
or are physically adsorbed by the silica powder. Examples of such treating 
agents include hexamethyldisilazane, trimethylsilane, 
trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, 
ethyltrichlorosilane, allyldimethylchlorosilane, 
allylphenyldichlorosilane, benzyldimethylchlorosilane, 
bromomethyldimethylchlorosilane, .alpha.-chloroethyltrichlorosilane, 
.beta.-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, 
triorganosilylmercaptans such as trimethylsilylmercaptan, triorganosilyl 
acrylates, vinyldimethylacetoxysilane, dimethylethoxysilane, 
dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 
1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 
dimethylpolysiloxane having 2 to 12 siloxane units per molecule and each 
containing one hydroxyl group bonded to Si at the terminal units. These 
may be used alone or as a mixture of two or more compounds. 
The above-mentioned treating agent may preferably be used in an amount of 
1-40 wt. % based on the weight of the silica fine powder. However, the 
above treating agent may be used so that the final product of the treated 
silica fine powder shows positive chargeability. 
In the present invention, titanium oxide (TiO.sub.2) powder preferably 
having a BET specific surface area of 50-400 m.sup.2 /g may be used 
instead of the silica fine powder. Further, a powder mixture of the silica 
fine powder and the titanium oxide fine powder may also be used. 
In the present invention, it is preferred to add fine powder of a 
fluorine-containing polymer such as polytetrafluoroethylene, 
polyvinylidene fluoride, or tetrafluoroethylene-vinylidene fluoride 
copolymer. Among these, polyvinylidene fluoride fine powder is 
particularly preferred in view of fluidity and abrasiveness. Such powder 
of a fluorine-containing polymer may preferably be added to the toner in 
an amount of 0.01-2.0 wt. %, more preferably 0.02-1.5 wt. %, particularly 
0.02-1.0 wt. %. 
In the non-magnetic toner wherein the silica fine powder and the 
above-mentioned fluorine-containing fine powder are combined, while the 
reason is not necessarily clear, there occurs a phenemenon such that the 
state of the presence of the silica attached to the toner particle is 
stabilized and, for example, the attached silica is prevented from 
separating from the toner particle so that the effect thereof on toner 
abrasion and carrier or sleeve contamination are prevented from 
decreasing, and the stability in chargeability can further be enhanced. 
As the colorant usable in the present invention as desired, a known dye 
and/or pigment may be used. Example thereof may include: carbon black, 
Phthalocyanine Blue, Peacock Blue, Permanent Red, Lake Red, Rhodamine 
Lake, Hansa Yellow, Permanent Yellow, Benzidine Yellow, etc. 
The colorant content may preferably be 0.1-20 wt. parts, more preferably 
0.5-20 wt. parts, per 100 wt. parts of a binder resin. Further, in order 
to improve the transparency of an OHP (overhead projector) film to which a 
toner image has been fixed, the colorant content may preferably be 12 
parts or smaller, more preferably 0.5-9 wt. parts, per 100 wt. parts of a 
binder resin. 
Another optional additive may be mixed in the non-magnetic toner of the 
present invention as desired. Such optional additives to be used include, 
for example, lubricants such as zinc stearate; abrasives such as cerium 
oxide and silicon carbide; flowability improvers such as colloidal silica 
and aluminum oxide; anti-caking agents; or conductivity-imparting agents 
such as carbon black and tin oxide. For example, when 0.1-5 wt. % of a 
conductivity-imparting agent such as carbon black and titanium oxide is 
added to the toner, excess charging thereof on a sleeve is suppressed, 
whereby a stable charging state is retained. When spherical fine resin 
powder having an average particle size of 0.05-3 microns, preferably 0.1-1 
micron is added to the toner a, similar effect can be obtained and the 
sharpness of an image may be enhanced. The addition amount thereof may 
preferably be 0.01-10 wt. %, more preferably 0.05-5 wt. %, particularly 
0.05-2 wt. %, based on the weight of the toner. Such spherical fine resin 
powder may preferably comprise a vinyl-type polymer or copolymer, more 
preferably an alkyl methacrylate-type polymer or copolymer. The 
above-mentioned spherical fine resin powder may preferably have a charging 
polarity reverse to, or a weak charging polarity the same as, that of the 
non-magnetic toner. 
In order to improve releasability in hot-roller fixing, it is also a 
preferred embodiment of the present invention to add to the non-magnetic 
toner a waxy material such as low-molecular weight polyethylene, 
low-molecular weight polypropylene, microcrystalline wax, carnauba wax, 
sasol wax or paraffin wax, preferably in an amount of 0.5-5 wt. %. 
The carrier usable in the present invention may include: magnetic material 
powder such as iron powder, ferrite powder or products obtained by 
treating these powders with a resin; glass beads, or non-magnetic metal 
oxide particles, or products obtained by treating these particle with a 
resin. 
The carrier may preferably be used in an amount of 10-1000 wt.parts, more 
preferably 30-500 wt.parts, per 10 wt.parts of the non-magnetic toner. In 
view of the matching with the non-magnetic toner according to the present 
invention having a relatively small particle size, the carrier may 
preferably have a volume-average particle size of 4-100 microns, more 
preferably 10-50 microns. 
The non-magnetic toner for developing electrostatic images according to the 
present invention may be produced by sufficiently mixing a vinyl or 
non-vinyl thermoplastic resin such as those enumerated hereinbefore, and 
an optional additive such as a pigment or dye as colorant, a charge 
controller, another additive, etc., by means of a mixer such as a ball 
mill, etc.; then melting and kneading the mixture by hot kneading means 
such as hot rollers, kneader and extruder to disperse or dissolve the 
pigment or dye in the melted resin; cooling and crushing the mixture; and 
subjecting the powder product to precise classification to form the 
non-magnetic toner according to the present invention. 
The non-magnetic toner of the present invention may be used for a 
two-component type image forming method in combination with magnetic 
particles (carrier). 
Such a two-component developer may particularly and preferably be used in 
an image forming method wherein a magnetic particle regulation means is 
disposed opposite to a toner-carrying member; a magnetic brush is formed 
on the surface of toner-carrying member upstream of the magnetic particle 
regulation means with respect to the moving direction of the 
toner-carrying member, on the basis of magnetic force due to a magnetic 
field generation means such as a magnet; a thin layer of a non-magnetic 
toner is formed on the toner-carrying member while regulating the magnetic 
brush by the magnetic particle regulation member; and an alternating 
electric field is applied between the toner-carrying member and a latent 
image-bearing member to attach the non-magnetic toner to the latent 
image-bearing member thereby to effect development. 
Such developing method is specifically explained with reference to FIGS. 1 
and 2. 
The developing apparatus shown in FIG. 1 comprises a latent image-bearing 
member 3 such as a photosensitive drum, a developer container 21, a 
non-magnetic sleeve 22 as a toner-carrying member, a fixed magnet 23, a 
magnetic or non-magnetic blade 24, a member 26 for limiting a circulation 
region for magnetic particles, a container portion 29 for collecting a 
developer, a member 30 for preventing scattering, a magnetic member 31, 
and a bias power supply 34. In FIG. 1, a reference numeral 27 denotes 
magnetic particles (carrier), numeral 28 denotes a non-magnetic toner, and 
numeral 32 denotes a developing zone. 
The sleeve 22 is rotated in the arrow b direction and the magnetic 
particles 27 circulate in the arrow c direction along with such rotation. 
Based on such movement, the contact and/or rubbing between the sleeve 
surface and the magnetic particle layer occurs, whereby a layer of the 
non-magnetic particles is formed on the sleeve surface. While the magnetic 
particles circulate in the arrow c direction, a part thereof is regulated 
to a predetermined amount by the gap or clearance between the magnetic or 
non-magnetic blade 24 and the sleeve 22, and applied onto the non-magnetic 
developer layer. In this arrangement, the non-magnetic toner (inclusive of 
a non-magnetic toner to which an external additive such as hydrophobic 
silica has been added) is applied onto both of the sleeve surface and the 
magnetic particle surfaces, whereby there is obtained an effect equivalent 
to that obtained by increasing the surface are of the sleeve 22. 
In the developing zone 32, one magnetic pole of the fixed magnet 23 is 
disposed opposite to the latent image-bearing surface to form a clear 
magnetic pole (S.sub.1) for development, and the toner particles are 
caused to fly from the sleeve surface and magnetic particle surfaces to 
the latent image-bearing surface, under the action of the alternating 
electric field, thereby to effect development. 
Next, such developing phenomenon is explained in more detail with reference 
to FIG. 2. 
In the embodiment as shown in FIG. 2, an electrostatic latent image (a dark 
portion) formed on a photosensitive drum 1 comprises negative charges, the 
direction of the electric field based on the electrostatic latent image is 
represented by an arrow d. The direction of the electric field based on 
the alternating voltage changes alternately. In the phase wherein a 
positive component is applied to the sleeve 22 side, the direction of the 
electric field based on the alternating voltage corresponds to that based 
on the latent image. At this time, the amount of charges injected to an 
ear 51 by the electric field becomes maximum, and accordingly the ear 51 
assumes a maximum erection state as shown in FIG. 2, whereby the long ear 
51 is lengthened to the surface of the photosensitive drum 1. 
On the other hand, the toner particles 28 disposed on the sleeve 22 and the 
magnetic particle 27 are, e.g., positively charged, and they are 
transferred to the photosensitive drum 1 under the action of the electric 
field formed in the space. At this time, the ears 51 are erected in a 
coarse state and the surface of the sleeve 22 is exposed, whereby the 
toner 28 is released from both of the surface of the sleeve 22 and the 
surface of the ear 51. In addition, charges having the same polarity as 
that of the toner 28 are present in the ear 51, the toner 28 disposed on 
the ear 51 becomes more movable due to the electric repulsion. 
In the phase wherein a negative component is applied to the sleeve 22 side, 
the direction of the electric field (arrow e) based on the alternating 
voltage is reverse to that (arrow d) based on the latent image, as shown 
in FIG. 2. Accordingly, the electric field in this space is strengthened 
in the reverse direction and the amount of charges injected to the ear 51 
becomes relatively small, whereby the ears 51 assume a contact state 
wherein they are shortened corresponding to the amount of the injected 
charges. 
On the other hand, because the toner particles 28 disposed on the 
photosensitive drum 1 are positively charged as mentioned above, they are 
reversely transferred to the surface of the sleeve 22 or the surfaces of 
the magnetic particles 27 under the action of the electric field formed in 
the space. 
Thus, the toner particles 28 are reciprocated between the photosensitive 
drum 1 and the sleeve 22 surface or the magnetic particle 27 surfaces. As 
the space between the photosensitive drum 1 and the sleeve 22 becomes 
larger due to rotation, the electric field becomes weaker, thereby to 
complete development. 
In the ear 51, there are present charges including triboelectric charges 
due to rubbing with the toner 28, or charges injected by mirror image 
force, or the action of the alternating electric field applied between the 
electrostatic latent image formed on the photosensitive drum 1 and the 
sleeve 22. The condition of such charges changes depending on the 
charge-discharge time constant which is determined by the material 
constituting the magnetic particles 27, etc. 
As described above, the ear 51 of the magnetic particles 27 assumes a 
minute and intense vibration state. 
After the developing operation, the magnetic particles 27 and toner 
particles 28 not used for the development are recovered to the developer 
container along with the rotation of the sleeve 22. 
The sleeve 22 can be a cylinder of paper or synthetic resin. When the 
sleeve is constituted by imparting electroconductivity to the surface of 
such cylinder or by using a conductive material such as aluminum, brass 
and stainless steel, it may be used as an electrode roller for 
development. 
The non-magnetic toner according to the present invention, when used as 
one-component developer, may preferably be applied to an image forming 
method wherein a latent image is developed while toner particles are 
caused to fly from a toner-carrying member such as a cylindrical sleeve to 
a latent image-carrying member such as a photosensitive member. 
In such case, the non-magnetic toner is supplied with triboelectric charge 
mainly due to the contact thereof with the sleeve surface and applied onto 
the sleeve surface in a thin layer form. The thin layer of the 
non-magnetic toner is formed so that the thickness thereof is smaller than 
the clearance between the photosensitive member and the sleeve in a 
developing zone. In the development of a latent image formed on the 
photosensitive member, it is preferred to cause the non-magnetic toner 
particles having triboelectric charge to fly from the sleeve to the 
photosensitive member, while applying an alternating electric field 
between the photosensitive member and the sleeve. 
Examples of the alternating electric field may include a pulse electric 
field, or an electric field based on an AC bias or a superposition of AC 
and DC biases. 
FIG. 6 shows an embodiment of the method and apparatus using a developer 
comprising the one-component type non-magnetic toner according to the 
present invention. 
Referring to FIG. 6, an electrostatic latent image is formed on a 
cylindrical electrostatic image-bearing member 101 by a known 
electrophotographic process such as the Carlson process or NP process. On 
the other hand, an insulating non-magnetic toner 105 contained in a hopper 
103 as a toner supply means is applied onto a toner-carrying member 102, 
while regulating the thickness of the toner layer by an application means 
104. The above-mentioned latent image is developed with the thus applied 
toner. 
The toner-carrying member 102 may be a developing roller comprising a 
stainless steel cylinder. The material for the developing roller can also 
be aluminum or another metal. In addition, the developing roller can be a 
metal roller coated with a resin in order to triboelectrically charge the 
toner a to more desirable polarity, or can comprise an electroconductive 
non-metal material. 
At the both ends of the cylindrical toner-carrying member 102 as shown in 
FIG. 8, two disk-shaped spacer rollers 108 of, e.g., high density 
polyethylene are respectively disposed so that the axes thereof correspond 
to the rotation axis of the toner-carrying member 102. When the developing 
apparatus is assembled so that the spacer rollers are caused to contact 
the both ends of the electrostatic image-bearing member 101, the clearance 
between the electrostatic image-bearing member 101 and the toner-carrying 
member 102 may be retained so that it is larger than the thickness of the 
toner layer to be applied onto the toner-carrying member 102. 
The above-mentioned clearance may preferably be 100-500 microns, more 
preferably 150-300 microns. If the clearance is too large, the 
electrostatic force due to the latent image formed on the electrostatic 
image-bearing member 101 which affects the non-magnetic toner applied onto 
the toner-carrying member 102 becomes weaker, the image quality 
deteriorates, and particularly, it is difficult to visualize a thin line 
image by development. On the other hand if, the clearance is too small, 
there can be enhanced a risk such that the toner applied on the 
toner-carrying member 102 is compressed between the toner-carrying member 
102 and the electrostatic image-bearing member 101 becomes agglomerated. 
Incidentaally, the spacer roller 108 may preferably have a disk-like shape 
having a diameter larger than that of the sleeve 102, and a thickness of 
about 5 mm-1 cm. Two spacer rollers are generally disposed at the both 
ends of the cylindrical sleeve 102, so that the center thereof corresponds 
to the rotation axis of the sleeve 102 and they contact the photosensitive 
drum 101. The spacer roller may be disposed so as to be rotatable or not. 
In FIG. 6, reference numeral 106 denotes a power supply for developing bias 
for applying a voltage between the toner-carrying member 102 and the 
electrostatic image-bearing member 101. The developing bias voltage used 
herein may preferably one as disclosed in Japanese Patent Publication 
(Kokoku) No. 32375/1983. 
Incidentally, in the present invention, the thin-line reproducibility may 
be measured in the following manner. 
An original image comprising thin lines accurately having a width of 100 
microns is copied under a suitable copying condition, i.e., a condition 
such that a circular original image having a diameter of 5 mm and an image 
density of 0.3 (halftone) is copied to provide a copy image having an 
image density of 0.3-0.5, thereby to obtain a copy image as a sample for 
measurement. An enlarged monitor image of the sample is formed by means of 
a particle analyzer (Luzex 450, mfd. by Nihon Regulator Co. Ltd.) as a 
measurement device, and the line width is measured by means of an 
indicator. Because the thin line image comprising toner particles has 
unevenness in the width direction, the measurement points for the line 
width are determined so that they correspond to the average line width, 
i.e., the average of the maximum and minimum line widths. Based on such 
measurement, the value (%) of the thin-line reproducibility is calculated 
according to the following formula: 
##EQU1## 
Further, in the present invention, the resolution may be measured in the 
following manner. 
There are formed ten species of original images comprising a pattern of 
five thin lines which have equal line width and are disposed at equal 
intervals equal to the line width. In these ten species of original 
images, thin lines are respectively drawn so that they provide densities 
of 2.8, 3.2, 3.6, 4.0, 4.5, 5.0, 5.6, 6.3, 7.1, and 8.0 lines per 1 mm. 
These ten species of original images are copied under the above-mentioned 
suitable copying conditions to form copy images which are then observed by 
means of a magnifying glass. The value of the resolution is so determined 
that it corresponds to the maximum number of thin lines (lines/mm) of an 
image wherein all the thin lines are clearly separated from each other. As 
the above-mentioned number is larger, it indicates a higher resolution. 
Hereinbelow, the present invention will be described in further detail with 
reference to Examples. In the following formulations, "parts" are parts by 
weight. 
EXAMPLE 1 
______________________________________ 
Styrene/butyl acrylate/divinyl benzene 
100 wt. parts 
copolymer (copolymerization wt. ratio: 
80/19.5/0.5, weight-average molecular 
weight: 320,000) 
Nigrosin 4 wt. parts 
(number-average particle size: about 
3 microns) 
Low-molecular weight propylene-ethylene 
4 wt. parts 
copolymer 
Carbon black 5 wt. parts 
______________________________________ 
The above ingredients were well blended in a blender and melt-kneaded at 
150.degree. C. by means of a two-axis extruder. The kneaded product was 
cooled, coarsely crushed by a cutter mill, finely pulverized by means of a 
pulverizer using jet air stream, and classified by a fixed-wall type 
wind-force classifier (DS-type Wind-Force Classifier, mfd. by Nippon 
Pneumatic Mfd. Co. Ltd.) to obtain a classified powder product. Ultra-fine 
powder and coarse power were simultaneously and precisely removed from the 
classified powder by means of a multi-division classifier utilizing a 
Coanda effect (Elbow Jet Classifier available from Nittetsu Kogyo K.K.), 
thereby to obtain black fine powder (non-magnetic toner) having a 
number-average particle size of 7.7 microns. The thus obtained 
non-magnetic toner showed a saturation magnetization of 0 emu/g with 
respect to an external magnetic field of 5000 oersted. 
The number-basis distribution and volume-basis distribution of the thus 
obtained non-magnetic toner of positively chargeable black fine powder 
were measured by means of a Coulter counter Model TA-II with a 100 
micron-aperture in the above-described manner. The thus obtained results 
are shown in the following Table 1. 
TABLE 1 
______________________________________ 
% by number (N) 
% by volume (V) 
Number of Distri- Accumu- 
Distri- 
Accumu- 
Size (.mu.m) 
particles bution lation bution 
lation 
______________________________________ 
2.00-2.52 
1581 1.5 1.5 0.0 0.0 
2.52-3.17 
4125 3.8 5.3 0.0 0.0 
3.17-4.00 
9117 8.4 13.6 1.5 1.5 
4.00-5.04 
18908 17.4 31.0 6.7 8.2 
5.04-6.35 
25970 23.9 54.9 16.9 25.1 
6.35-8.00 
28560 26.3 81.2 33.3 58.4 
8.00-10.08 
17300 15.9 97.1 31.5 89.9 
10.08-12.70 
3000 2.8 99.9 9.6 99.5 
12.70-16.00 
101 0.1 100.0 0.5 100.0 
16.00-20.20 
0 0.0 100.0 0.0 100.0 
20.20-25.40 
0 0.0 100.0 0.0 100.0 
25.40-32.00 
0 0.0 100.0 0.0 100.0 
32.00-40.30 
0 0.0 100.0 0.0 100.0 
40.30-50.80 
0 0.0 100.0 0.0 100.0 
______________________________________ 
FIG. 3 schematically shows the classification step using the multi-division 
classifier, and FIG. 4 shows a sectional perspective view of the 
multi-division classifier. 
0.5 wt. parts of positively chargeable hydrophobic dry process silica (BET 
specific surface area: 200 m.sup.2 /g) were added to 100 wt. parts of the 
non-magnetic toner of black fine powder obtained above and mixed therewith 
by means of a Henschel mixer. Further, 10 parts of the resultant 
non-magnetic toner (external addition product) were mixed with 90 parts of 
ferrite carrier (volume-average particle size of 40 microns) thereby to 
obtain a positively chargeable two-component developer comprising a 
non-magnetic toner. 
The above-mentioned non-magnetic toner showed a particle size distribution 
and various characteristics as shown in Table 3 appearing hereinafter. 
The thus prepared one-component developer was charged in an image forming 
(developing) device as shown in FIG. 1, and a developing test was 
conducted. 
The developing conditions used in this instance is explained with reference 
to FIG. 1. 
Referring to FIG. 1, a photosensitive drum 3 was rotated in the arrow a 
direction at a peripheral speed of 100 mm/sec. A stainless steel sleeve 22 
comprised 20 mm-dia. cylinder (thickness: 0.8 mm) of which surface had 
been subjected to blasting treatment by using spherical glass beads, and 
was rotated in the arrow b direction at a peripheral speed of 150 mm/sec. 
On the other hand, a fixed magnet 23 of a ferrite sinter-type was disposed 
in the rotating sleeve 22 so that the magnetic poles thereof were disposed 
as shown in FIG. 2 and it provided a maximum magnetic flux density of 
about 980 gauss at the surface of the sleeve. A non-magnetic blade 24 
comprised a 1.2 mm-thick stainless steel blade, and the clearance between 
the blade and the sleeve was set to 400 microns. 
Opposite to the sleeve 22, a laminate-type organic photoconductor (OPC) 
drum 3 was disposed. On the surface of the drum 3 an electrostatic latent 
image comprising a charge pattern comprising a dark part of -600 V and a 
light part of -150 V was formed. The clearance between the drum 3 and the 
sleeve 22 surface was set to 350 microns. 
By using the above-mentioned apparatus, normal development was conducted by 
applying a voltage having a frequency of 1800 Hz, a peak-to-peak voltage 
of 1300 V and a central value of -200 V, to the sleeve 22 by means of a 
power supply 34. Thereafter, the resultant toner image was transferred to 
plain paper by using a negative corona transfer means and then fixed 
thereto by a hot pressure roller fixing means. Such image formation tests 
were successively conducted 10,000 times thereby to provide 10,000 sheets 
of toner images. The thus obtained results are shown in Table 4 appearing 
hereinafter. 
As apparent from Table 4, both the line portion and large image area 
portion of the letters showed a high image density. The non-magnetic toner 
of the present invention was excellent in thin-line reproducibility and 
resolution, and retained good image quality was obtained in the initial 
stage even after 10,000 sheets of image formations. Further, the copying 
cost per one sheet was low, whereby the non-magnetic toner of the present 
invention was excellent in economical characteristics. 
Hereinbelow, the multi-division classifier and the classification step used 
in this instance are explained with reference to FIGS. 3 and 4. 
Referring to FIGS. 3 and 4, the multidivision classifier has side walls 72, 
73 and 74, and a lower wall 75. The side wall 73 and the lower wall 75 are 
provided with knife edge-shaped classifying wedges 67 and 68, 
respectively, whereby the classifying chamber is divided into three 
sections. At a lower portion of the side wall 72, a feed supply nozzle 66 
opening into the classifying chamber is provided. A Coanda block 76 is 
disposed along the lower tangential line of the nozzle 66 so as to form a 
long elliptic arc shaped by bending the tangential line downwardly. The 
classifying chamber has an upper wall 77 provided with a knife edge-shaped 
gas-intake wedge 69 extending downwardly. Above the classifying chamber, 
gas-intake pipes 64 and 65 opening into the classifying chamber are 
provided. In the intake pipes 64 and 65, a first gas introduction control 
means 70 and a second gas introduction control means 71, respectively, 
comprising, e.g., a damper, are provided; and also static pressure gauges 
78 and 79 are disposed communicatively with the pipes 64 and 65, 
respectively. At the bottom of the classifying chamber, exhaust pipes 61, 
62 and 63 having outlets are disposed corresponding to the respective 
classifying sections and opening into the chamber. 
Feed powder to be classified is introduced into the classifying zone 
through the supply nozzle 66 under reduced pressure. The feed powder thus 
supplied is caused to fall along curved lines 30 due to the Coanda effect 
given by the Coanda block 76 and the action of the streams of high-speed 
air, so that the feed powder is classified into coarse powder 61, black 
fine powder 62 having prescribed volume-average particle size and particle 
size distribution, and ultra-fine powder 63. 
EXAMPLE 2 
A non-magnetic toner was prepared in the same manner as in Example 1 except 
that the micropulverization and classification conditions were controlled 
to obtain a toner having characteristics as shown in Table 3 appearing 
hereinafter. The thus obtained toner was evaluated in the same manner as 
in Example 1. 
As a result, as shown in Table 4 appearing hereinafter, clear high-quality 
images were stably obtained. 
EXAMPLE 3 
A non-magnetic toner was prepared in the same manner as in Example 1 except 
that the micropulverization and classification conditions were controlled 
to obtain a toner having characteristics as shown in Table 3 appearing 
hereinafter. The thus obtained toner was evaluated in the same manner as 
in Example 1. 
As a result, as shown in Table 4 appearing hereinafter, clear high-quality 
images were stably obtained. 
EXAMPLE 4 
0.5 wt. parts of positively chargeable hydrophobic dry process silica and 
0.3 wt. parts of polyvinylidene fluoride fine powder (average primary 
particle size: about 0.3 micron, weight-average molecular weight (Mw): 
300,000) were added to 100 wt. parts of the black fine powder 
(non-magnetic toner) obtained in Example 1, and mixed therewith by means 
of a Henschel mixer thereby to obtain a non-magnetic toner (external 
addition product). By using the thus obtained non-magnetic toner, a 
two-component developer was prepared in the same manner as in Example 1. 
The thus obtained developer was evaluated in the same manner as in Example 
1. As a result, as shown in Table 4 appearing hereinafter, there were 
obtained better images excellent in image density and stability in image 
quality. 
EXAMPLE 5 
______________________________________ 
Crosslinked polyester resin 
100 wt. parts 
(Mw = 50,000, glass transition 
point (Tg) = 60.degree. C.) 
3,5-di-t-butylsalicylic acid 
1 wt. part 
metal salt 
Low-molecular weight propylene- 
3 wt. parts 
ethylene copolymer 
Carbon black 5 wt. parts 
______________________________________ 
By using the above materials, black fine powder was prepared in the same 
manner as in Example 1. 
0.3 wt. parts of negatively chargeable hydrophobic silica (BET specific 
surface area: 130 m.sup.2 /g) were added to 100 wt. parts of the black 
fine powder obtained above and mixed therewith by means of a Henschel 
mixer thereby to obtain a negative chargeable non-magnetic toner (external 
addition product). 
The above-mentioned black fine powder showed a particle size distribution, 
etc., as shown in Table 3 appearing hereinafter. 10 parts of the 
non-magnetic toner (external addition product) were mixed with 90 parts of 
ferrite carrier (volume-average particle size: 35 microns) to obtain a 
two-component developer. 
The thus prepared two-component developer was charged in a copying machine 
having an amorphous silicon photosensitive drum capable of forming a 
positive electrostatic latent image (NP-7550, mfd. by Canon K.K.) which 
had been modified so that it could use a two-component developer, and 
image formation tests of 10,000 sheets using normal development were 
conducted. 
As a result, as shown in Table 4 appearing hereinafter, clear high-quality 
images were stably obtained. 
COMATIVE EXAMPLE 1 
Black fine powder (non-magnetic toner) as shown in Table 3 was prepared in 
the same manner as in Example 1, except that two fixed-wall type 
wind-force classifiers used in Example 1 were used for the classification 
instead of the combination of the fixed-wall type wind-force classifier 
and the multi-division classifier used in Example 1. 
In the thus prepared non-magnetic toner of Comparative Example 1, the 
percentage by number of the non-magnetic toner particles of 5 microns or 
smaller was smaller than the range thereof defined in the present 
invention, the volume-average particle size was larger than the range 
thereof defined in the present invention, and the value of (% by number 
(N))/(% by volume (V)) of the non-magnetic toner particles of 5 microns or 
smaller was larger than the range thereof defined in the present 
invention, whereby the conditions required in the present invention were 
not satisfied. The particle size distribution of magnetic toner obtained 
above is shown in the following Table 2. 
TABLE 2 
______________________________________ 
% by number (N) 
% by volume (V) 
Number of Distri- Accumu- 
Distri- 
Accumu- 
Size (.mu.m) 
particles bution lation bution 
lation 
______________________________________ 
2.00-2.52 
437 1.3 1.3 0.0 0.0 
2.52-3.17 
507 1.5 2.8 0.0 0.0 
3.17-4.00 
613 1.8 4.6 0.0 0.0 
4.00-5.04 
1308 3.8 8.4 0.5 0.5 
5.04-6.35 
3658 10.8 19.2 2.6 3.1 
6.35-8.00 
6750 19.9 39.1 8.7 11.8 
8.00-10.08 
8628 25.4 64.5 17.6 29.4 
10.08-12.70 
7474 22.0 86.4 29.2 58.6 
12.70-16.00 
3812 11.2 97.7 29.1 87.7 
16.00-20.20 
698 2.1 99.7 9.8 97.5 
20.20-25.40 
82 0.2 100.0 2.1 99.6 
25.40-32.00 
11 0.0 100.0 0.4 100.0 
32.00-40.30 
1 0.0 100.0 0.0 100.0 
40.30-50.80 
1 0.0 100.0 0.0 100.0 
______________________________________ 
0.5 wt. parts of positively chargeable hydrophobic dry process silica were 
added to 100 wt. parts of the black fine powder obtained above mixed 
therewith in the same manner as in Example 1 thereby to obtain a 
non-magnetic toner (external addition product). 10 parts of the 
non-magnetic toner (external addition product) was mixed with 90 parts of 
ferrite carrier (volume-average particle size: 40 microns) to obtain a 
two-component developer. The thus obtained developer was subjected to 
image formation tests under the same conditions as in Example 1. 
In the resultant images, the toner particles remarkably protruded from the 
latent image formed on the photosensitive member, the thin-line 
reproducibility was 145% which was poorer than that in Example 1, and the 
resolution was 4.0 lines/mm. Further, after 10,000 sheets of image 
formations, the image density in the solid black pattern decreased and the 
thin line reproducibility and resolution deteriorated. Moreover, the toner 
consumption was large. 
The results are shown in Table 4 appearing hereinafter. 
COMATIVE EXAMPLE 2 
Evaluation was conducted in the same manner as in Example 1 except that a 
toner as shown in Table 3 was used instead of the non-magnetic toner used 
in Example 1. 
In the resultant images, thin lines were contaminated in several places 
presumably due to the aggregates of toner particles, and the resolution 
was 3.6 lines/mm. The solid black pattern, particularly the inner portion 
thereof, had a lower image density than that in the line image and the 
edge portion of the image. Further, fog contamination in spot forms 
occurred, and the image quality was further deteriorated in successive 
copying. 
COMATIVE EXAMPLE 3 
Evaluation was conducted in the same manner as in Example 1 except that a 
toner as shown in Table 3 was used instead of the non-magnetic toner used 
in Example 1. 
The developed image formed on the drum had relatively good image quality, 
while it was somewhat disturbed. However, the toner image was remarkably 
disturbed in the transfer step, whereby transfer failure occurred and the 
image density decreased. Particularly, in successive copying, the image 
density was further decreased and the image quality was further 
deteriorated because poor toner particles remained and accumulated in the 
developing device. 
COMATIVE EXAMPLE 4 
Evaluation was conducted in the same manner as in Example 1 except that a 
toner as shown in Table 3 was used instead of the non-magnetic toner used 
in Example 1. 
In the resultant images, the image density was low and the contour was 
unclear and the sharpness was lacking, because the cover-up of toner 
particles to the edge portions of images was poor. Further, the resolution 
and gradational characteristic were also poor. When successive copying was 
conducted, sharpness, thin-line reproducibility and resolution were 
further deteriorated. 
COMATIVE EXAMPLE 5 
Evaluation was conducted in the same manner as in Example 1 except that a 
toner as shown in Table 3 was used instead of the non-magnetic toner used 
in Example 1. 
In the resultant images, the image density, resolution and the thin-line 
reproducibility were all poor. Further, the edge portion of the image 
lacked in sharpness, and the thin lines were interrupted and unclear. 
The results in Examples 1-5 and Comparative Examples 1-5 described above 
are inclusively shown in the following Tables 3 and 4. 
TABLE 3 
__________________________________________________________________________ 
Particle size distribution of toner 
% by number 
% by volume 
% by number 
Volume-average 
(% by number)/(% by 
of particles 
of particles 
of particles 
particle size 
volume) of particles 
.ltoreq.5 .mu.m 
.gtoreq.16 .mu.m 
of 8-12.7 .mu.m 
(.mu.m) .ltoreq.5 .mu.m 
__________________________________________________________________________ 
Example 
1 31 0.0 19 7.7 3.8 
2 21 0.5 20 8.6 4.8 
3 48 0.2 13 6.8 3.2 
4 31 0.0 19 7.7 3.8 
5 43 0.5 10 7.4 4.5 
Comparative 
Example 
1 8.4 12.3 47 12.3 16.8 
2 64 0.1 5 6.2 1.4 
3 27 4 15 7.6 6.4 
4 41 0.3 7 6.7 2.1 
5 14 0.2 51 9.9 2.9 
__________________________________________________________________________ 
TABLE 4-1 
______________________________________ 
Initial stage 
Dmax *.sup.1 
Dmax *.sup.2 
Thin-line 
(5 mm (solid black 
reproduc- Resolution 
diameter) 
portion) ibility (lines/mm) 
______________________________________ 
Example 
1 1.30 1.30 104% 6.3 
2 1.31 1.29 103% 6.3 
3 1.29 1.27 106% 6.3 
4 1.32 1.32 104% 6.3 
5 1.33 1.32 104% 7.1 
Comparative 
1.28 1.27 125% 4.5 
Example 1.27 1.19 130% 4.5 
1.22 1.20 110% 5.6 
1.21 1.18 115% 4.0 
1.16 1.15 135% 4.0 
______________________________________ 
*.sup.1 The image density of a copy image obtained by copying an original 
circular image which had a diameter of 5 mm and comprised a solid black 
pattern. 
*.sup.2 The image density of a copy image obtained by copying an A3 
original image which comprised of a solid black pattern. 
TABLE 4-2 
__________________________________________________________________________ 
After 10,000 sheets of image formations 
Dmax Dmax Thin-line 
Resolution 
Toner consumption 
(5 mm diameter) 
(Solid black portion) 
reproducibility 
(lines/mm) 
(g/one sheet) 
__________________________________________________________________________ 
Example 
1 1.33 1.33 105% 6.3 0.023 
2 1.32 1.32 103% 6.3 0.021 
3 1.30 1.28 108% 5.6 0.022 
4 1.35 1.34 102% 6.3 0.022 
5 1.36 1.36 101% 7.1 0.023 
Comparative 
Example 
1 1.28 1.22 145% 4.0 0.045 
2 1.25 1.10 150% 3.6 0.039 
3 1.18 1.05 135% 4.0 0.032 
4 1.20 1.15 130% 4.0 0.031 
5 1.13 1.03 150% 3.6 0.036 
__________________________________________________________________________ 
EXAMPLE 6 
______________________________________ 
Styrene/butyl acrylate/divinyl benzene 
100 wt. parts 
copolymer (copolymerization wt. ratio: 
80/19.5/0.5, weight-average molecular 
weight: 320,000) 
Nigrosin 2 wt. parts 
(number-average particle size: about 
3 microns) 
Low-molecular weight propylene-ethylene 
3 wt. parts 
copolymer 
Carbon black 4 wt. parts 
______________________________________ 
The above ingredients were well blended in a blender and melt-kneaded at 
150.degree. C. by means of a two-axis extruder. The kneaded product was 
cooled, coarsely crushed by a cutter mill, finely pulverized by means of a 
pulverizer using a jet air stream, and classified by a fixed-wall type 
wind-force classifier to obtain a classified powder product. Ultra-fine 
powder and coarse power were simultaneously and precisely removed from the 
classified powder by means of a multi-division classifier utilizing a 
Coanda effect (Elbow Jet Classifier available from Nittetsu Kogyo K.K.), 
thereby to obtain black fine powder (non-magnetic toner) having a 
number-average particle size of 7.6 microns. 
The number-basis distribution and volume-basis distribution of the thus 
obtained non-magnetic toner of positively chargeable black fine powder 
were measured by means of a Coulter counter Model TA-II with a 100 
micron-aperture in the above-described manner. The thus obtained results 
are shown in the following Table 5. 
TABLE 5 
______________________________________ 
% by number (N) 
% by volume (V) 
Number of Distri- Accumu- 
Distri- 
Accumu- 
Size (.mu.m) 
particles bution lation bution 
lation 
______________________________________ 
2.00-2.52 
3693 2.5 2.5 0.0 0.0 
2.52-3.17 
7394 4.9 7.4 0.4 0.4 
3.17-4.00 
14758 9.8 17.2 1.9 2.3 
4.00-5.04 
27788 18.5 35.7 7.4 9.7 
5.04-6.35 
35956 23.9 59.6 17.9 27.6 
6.35-8.00 
36389 24.2 83.8 33.3 60.9 
8.00-10.08 
20707 13.8 97.6 29.8 90.8 
10.08-12.70 
3418 2.3 99.9 8.6 99.4 
12.70-16.00 
139 0.1 100.0 0.6 100.0 
16.00-20.20 
7 0.0 100.0 0.0 100.0 
20.20-25.40 
5 0.0 100.0 0.0 100.0 
25.40-32.00 
3 0.0 100.0 0.0 100.0 
32.00-40.30 
0 0.0 100.0 0.0 100.0 
40.30-50.80 
0 0.0 100.0 0.0 100.0 
______________________________________ 
FIG. 3 schematically shows the classification step using the multi-division 
classifier, and FIG. 4 shows a sectional perspective view of the 
multi-division classifier. 
0.6 wt. parts of positively chargeable hydrophobic dry process silica (BET 
specific surface area: 200 m.sup.2 /g) were added to 100 wt. parts of the 
black fine powder obtained above and mixed therewith by means of a 
Henschel mixer thereby to obtain a positively chargeable one-component 
developer comprising the non-magnetic toner (external addition product). 
The above-mentioned non-magnetic toner showed a particle size distribution 
and various characteristics as shown in Table 6 appearing hereinafter. 
The thus prepared one-component non-magnetic toner was charged in an image 
forming (developing) device as shown in FIG. 6, and a developing test was 
conducted. 
The developing conditions used in this instance are explained with 
reference to FIG. 6. In FIG. 6, the one-component developer 105 contained 
in a developer chamber 103 is applied in a thin layer form onto the 
surface of a cylindrical sleeve 102 of stainless steel as a toner-carrying 
means rotating in the direction of an arrow 107 by the medium of a means 
104 for forming the layer of the toner. The sleeve 102 is disposed near to 
a photosensitive drum 101, as an electrostatic image-holding means, 
comprising an organic photoconductor layer carrying a negative latent 
image. The minimum space between the sleeve 102 and the photosensitive 
drum 101 rotating in the direction of an arrow 109 is set to about 250 
microns. 
In the development, a bias of 2000 Hz/1300 Vpp obtained by superposing an 
AC bias and a DC bias was applied between the photosensitive drum 101 and 
the sleeve 102 by an alternating electric field-applying means 106. The 
layer of the one-component developer formed on the sleeve 102 had a 
thickness of about 25 microns, a charge amount per unit area of 
7.0.times.10.sup.-9 .mu.c/cm.sup.2, and a coating amount per unit area of 
0.60 mg/cm.sup.2. 
By using the above-mentioned device, a negative latent image formed on the 
photosensitive drum 101 was developed by causing the one-component 
developer 105 having positive triboelectric charge to fly to the latent 
image (normal development). Thereafter, the resultant toner image was 
transferred to plain paper by using a negative corona transfer means and 
then fixed thereto by a hot pressure roller fixing means. Such image 
formation tests were successively conducted 10,000 times thereby to 
provide 10,000 sheets of toner images. The thus obtained results are shown 
in Table 7 appearing hereinafter. 
As apparent from Table 7, both of the line portion and large image area 
portion of the letters showed a high image density. The non-magnetic toner 
of the present invention was excellent in thin-line reproducibility and 
resolution, and retained good image quality was obtained in the initial 
stage even after 10,000 sheets of image formations. Further, the copying 
cost per one sheet was low, whereby the magnetic toner of the present 
invention was excellent in economical characteristics. 
EXAMPLE 7 
A non-magnetic toner was prepared in the same manner as in Example 6 except 
that the micropulverization and classification conditions were controlled 
to obtain a toner having characteristics as shown in Table 6 appearing 
hereinafter. The thus obtained toner was evaluated in the same manner as 
in Example 6. 
As a result, as shown in Table 7 appearing hereinafter, clear high-quality 
images were stably obtained. 
EXAMPLE 8 
0.6 wt. parts of positively chargeable hydrophobic silica and 0.5 wt. parts 
of tin oxide fine powder (particle size: about 0.4 micron) were added to 
100 wt. parts of the black fine powder (non-magnetic toner) showing a 
particle size distribution as shown in Table 6, and mixed therewith by 
means of a Henschel mixer thereby to obtain a one-component non-magnetic 
developer. 
The thus obtained developer was evaluated in the same manner as in Example 
6. As a result, as shown in Table 7 appearing hereinafter, clear 
high-quality images were stably obtained. 
EXAMPLE 9 
0.6 wt. parts of positively chargeable hydrophobic dry process silica and 
0.2 wt. part of polyvinylidene fluoride fine powder (average primary 
particle size: about 0.3 microns, weight-average molecular weight (Mw): 
300,000) were added to 100 wt. parts of the black fine powder 
(non-magnetic toner) obtained in Example 6, and mixed therewith by means 
of a Henschel mixer thereby to obtain a one-component developer. 
The thus obtained developer was evaluated in the same manner as in Example 
1. As a result, as shown in Table 7 appearing hereinafter, there were 
obtained better images excellent in image density and image quality. 
EXAMPLE 10 
______________________________________ 
Crosslinked polyester resin 
100 wt. parts 
(Mw = 50,000, glass transition 
point (Tg) = 60.degree. C.) 
3,5-di-t-butylsalicylic acid 
1 wt. part 
metal salt 
Low-molecular weight propylene- 
3 wt. parts 
ethylene copolymer 
Carbon black 3 wt. parts 
______________________________________ 
By using the above materials, black fine powder was prepared in the same 
manner as in Example 6. 
0.3 wt. parts of negatively chargeable hydrophobic silica (BET specific 
surface area: 130 m.sup.2 /g) and 0.5 wt. parts of spherical paraticles 
(average particle size: about 0.3 micron) comprising an 
n-butylacrylate-methylmethacrylate copolymer were added to 100 wt. parts 
of the black fine powder (non-magnetic toner) obtained above and mixed 
therewith by means of a Henschel mixer thereby to obtain a negatively 
chargeable one-component non-magnetic developer. 
The above-mentioned black fine powder (non-magnetic toner) showed a 
particle size distribution, etc., as shown in Table 6 appearing 
hereinafter. 
The thus prepared one-component developer was charged in a copying machine 
(NP-7550, mfd. by Canon K.K.) having an amorphous silicon photosensitive 
drum capable of forming a positive electrostatic latent image and image 
formation tests of 10,000 sheets were conducted. 
As a result, as shown in Table 7 appearing hereinafter, clear high-quality 
images were stably obtained. 
EXAMPLE 11 
The positively chargeable one-component developer prepared in Example 6 was 
charged in a digital-type copying machine (NP-9330, mfd. by Canon K.K.) 
having an amorphous silicon photosensitive drum and image formation tests 
of 10,000 sheets were conducted by developing a positive electrostatic 
latent image by a reversal development system. 
As a result, as shown in Table 7 appearing hereinafter, the thin-line 
reproducibility and resolution were excellent and there were obtained 
clear images having a high gradational characteristic. 
COMATIVE EXAMPLE 6 
Black fine powder (non-magnetic toner) as shown in Table 6 was prepared in 
the same manner as in Example 6, except that two fixed-wall type 
wind-force classifiers used in Example 6 were used for the classification 
instead of the combination of the fixed-wall type wind-force classifier 
and the multi-division classifier used in Example 6. 
In the thus prepared non-magnetic toner of Comparative Example 6, the 
percentage by number of the magnetic toner particles of 5 microns or 
smaller was smaller than the range thereof defined in the present 
invention, the volume-average particle size was larger than the range 
thereof defined in the present invention, and the value of (% by number 
(N))/(% by volume (V)) was larger than the range thereof defined in the 
present invention, whereby the conditions required in the present 
invention were not satisfied. The particle size distribution of the 
non-magnetic toner obtained above is shown in the following Table 6. 
0.5 wt. parts of positively chargeable hydrophobic dry process silica were 
added to 100 wt. parts of the black fine powder obtained above mixed 
therewith in the same manner as in Example 6 thereby to obtain a 
one-component non-magnetic developer. The thus obtained developer was 
subjected to image formation tests under the same conditions as in Example 
6. 
The layer of the one-component developer formed on the sleeve 102 had a 
thickness of about 65 microns, charge amount per unit area of 
9.0.times.10.sup.-9 .mu.c/cm.sup.2, and a coating amount per unit area of 
1.1 mg/cm.sup.2. 
In the resultant images, the toner particles remarkably protruded from the 
latent image formed on the photosensitive member, the thin-line 
reproducibility was 145% which was poorer than that in Example 6, and the 
resolution was 3.6 lines/mm. Further, after 10,000 sheets of image 
formations, the image density in the solid black pattern decreased and the 
thin line reproducibility and resolution deteriorated. It was observed 
that the toner adhered to the application member 104 and the sleeve 102 
along with successive copying. Moreover, the toner consumption was large. 
The results are shown in Table 7 appearing hereinafter. 
COMATIVE EXAMPLE 7 
Evaluation was conducted in the same manner as in Example 1 except that a 
toner as shown in Table 7 was used instead of the non-magnetic toner used 
in Example 6. 
In the resultant images, thin lines were contaminated in several places 
presumably due to the aggregates of toner particles, and the resolution 
was 3.6 lines/mm. The solid black pattern, particularly the inner portion 
thereof, had a lower image density than that in the line image and the 
edge portion of the image. Further, fog contamination in spot forms 
occurred, and the image quality was further deteriorated in successive 
copying. 
COMATIVE EXAMPLE 8 
Evaluation was conducted in the same manner as in Example 6 except that a 
toner as shown in Table 6 was used instead of the non-magnetic toner used 
in Example 6. 
The developed image formed on the drum had relatively good image quality, 
although it was somewhat disturbed. However, the toner image was 
remarkably disturbed in the transfer step, whereby transfer failure 
occurred and the image density decreased. Particularly, in successive 
copying, the image density was further decreased and the image quality was 
further deteriorated because poor toner particles remained and accumulated 
in the developing device. 
COMATIVE EXAMPLE 9 
Evaluation was conducted in the same manner as in Example 6 except that a 
toner as shown in Table 6 was used instead of the non-magnetic toner used 
in Example 6. 
In the resultant images, the image density was low and the contour was 
unclear and the sharpness was lacking, because the cover-up of toner 
particles to the edge portions of images was poor. Further, the resolution 
and gradational characteristic were also poor. When successive copying was 
conducted, the sharpness, thin-line reproducibility and resolution were 
further deteriorated. 
COMATIVE EXAMPLE 10 
Evaluation was conducted in the same manner as in Example 6 except that a 
toner as shown in Table 6 was used instead of the non-magnetic toner used 
in Example 6. 
In the resultant images, the image density, resolution and the thin line 
reproducibility were all poor. Further, the edge portion of the image 
lacked sharpness, and the thin lines were interrupted and unclear. 
The results in Examples 6-11 and Comparative Examples 6-10 described above 
are inclusively shown in the following Tables 6 and 7. 
TABLE 6 
__________________________________________________________________________ 
Particle size distribution of toner 
% by number 
% by volume 
% by number 
Volume-average 
(% by number)/(% by 
of particles 
of particles 
of particles 
particle size 
volume) of particles 
.ltoreq.5 .mu.m 
.gtoreq.16 .mu.m 
of 8-12.7 .mu.m 
(.mu.m) .ltoreq.5 .mu.m 
__________________________________________________________________________ 
Example 
6 36 0.6 16 7.6 3.7 
7 21 0.4 22 8.8 4.8 
8 54 0.1 12 6.5 2.8 
9 36 0.6 16 7.6 3.7 
10 43 0.5 10 7.4 4.5 
11 36 0.6 16 7.6 3.7 
Comparative 
Example 
6 9.0 4.1 50 12.3 13.5 
7 68 0.1 5 6.0 1.5 
8 27 4 15 7.6 6.4 
9 41 0.3 7 6.7 2.1 
10 14 0.2 51 9.9 2.9 
__________________________________________________________________________ 
TABLE 7-1 
______________________________________ 
Initial stage 
Dmax Dmax Thin-line 
(5 mm (solid black 
reproduc- Resolution 
diameter) 
portion) ibility (lines/mm) 
______________________________________ 
Example 
6 1.33 1.32 105% 6.3 
7 1.32 1.30 105% 6.3 
8 1.28 1.27 107% 6.3 
9 1.35 1.33 102% 6.3 
10 1.33 1.32 102% 6.3 
11 1.35 1.32 102% 7.1 
Comparative 
Example 
6 1.25 1.20 145% 3.6 
7 1.25 1.15 150% 3.6 
8 1.20 1.18 120% 4.0 
9 1.15 1.12 130% 3.2 
10 1.12 0.98 140% 3.2 
______________________________________ 
TABLE 7-2 
__________________________________________________________________________ 
After 10,000 sheets of image formations 
Dmax Dmax Thin-line 
Resolution 
Toner consumption 
(5 mm diameter) 
(Solid black portion) 
reproducibility 
(lines/mm) 
(g/one sheet) 
__________________________________________________________________________ 
Example 
6 1.33 1.33 105% 6.3 0.023 
7 1.32 1.31 105% 6.3 0.022 
8 1.31 1.30 105% 6.3 0.021 
9 1.38 1.38 102% 7.1 0.023 
10 1.35 1.33 102% 6.3 0.020 
11 1.35 1.32 102% 7.1 0.022 
Comparative 
Example 
6 1.20 1.15 160% 3.2 0.050 
7 1.23 1.10 160% 3.2 0.040 
8 1.20 1.08 140% 3.6 0.036 
9 1.18 1.05 150% 3.2 0.030 
10 1.10 0.95 160% 3.2 0.035 
__________________________________________________________________________ 
EXAMPLE 13 
______________________________________ 
Polyester resin 100 wt. parts 
(polycondensation product of propoxidized 
bisphenol and fumaric acid) 
Colorant 3.5 wt. parts 
(C.I. Pigment Yellow 17) 
Negative charge controller 
4 wt. parts 
(dialkylsalicylic acid chromium complex) 
______________________________________ 
The above component were preliminarily mixed by means of a Henschel mixer 
sufficiently, and melt-kneaded by means of a three-roller mill at least 
two times. The kneaded product was cooled, coarsely crushed by a cutter 
mill, finely pulverized by means of a pulverizer using a jet air stream, 
and classified by a fixed-wall type wind-force classifier to obtain a 
classified powder product. Ultra-fine powder and coarse power were 
simultaneously and precisely removed from the classified powder by means 
of a multi-division classifier utilizing a Coanda effect (Elbow Jet 
Classifier available from Nittetsu Kogyo K.K.), thereby to obtain yellow 
fine powder (non-magnetic toner) having a number-average particle size of 
7.9 microns. 
0.5 wt. parts of hydropholic silica treated with hexamethyldisilosane were 
externally mixed with 100 wt. parts of the yellow fine powder to obtain a 
yellow toner as an external addition product (non-magnetic color toner). 
The thus obtained non-magnetic toner has a particle size distribution as 
shown in Table 8 appearing hereinafter. 
The non-magnetic color toner composition (external addition product) in an 
amount of 9 wt. parts was mixed with a Cu-Zn-Fe-basis ferrite carrier 
(average particle size: 48 microns, weight of 250 mesh-pass and 350 
mesh-on: 79 wt. %, true density: 4.5 g/m.sup.3) coated with about 0.5 wt. 
% of a 50:50 (wt.)-mixture of vinylidene fluoride-tetrafluoroethylene 
copolymer (copolymerization weight ratio =8:2) and styrene-2-ethylhexyl 
acrylate-methyl methacrylate copolymer (copolymerization weight ratio 
=45:20:35) so as to provide a total amount of 100 wt. parts, whereby a 
two-component developer was prepared. 
The two-component developer was charged in a color laser-type 
electrophotographic apparatus (PIXEL, mfd. by Canon K.K.) and subjected to 
an image formation test of 2,000 sheets by using reversal development 
system in a mono-color mode. The results are shown in Table 9 appearing 
hereinafter. 
As apparent from Table 9, both of the line portion and large image area 
portion of the letters showed a high image density. The non-magnetic toner 
of the present invention was excellent in thin-line reproducibility and 
resolution, and retained good image quality obtained in the initial stage 
even after 2,000 sheets of image formations. Further, the copying cost 
per one sheet was low, whereby the non-magnetic toner of the present 
invention was excellent in economical characteristics. 
Particularly, there was substantially no difference between the cover-up of 
the inner portion and that of the edge portion with respect to a solid 
image, and the cover-up of the inner portion of the solid image was 
uniform, whereby an image excellent in gloss characteristic was obtained. 
The gloss used herein was measured in the following manner. 
A gloss meter Model VG-10 (available from Nihon Denshoku K.K.) was used. A 
solid color image was used as a sample image. For measurement, a voltage 
of 6 volts was supplied to the gloss meter from a constant-voltage power 
supply, and the light-projecting angle and the light-receiving angle are 
respectively set to 60 degrees. 
Zero point adjustment and standard adjustment were conducted by using a 
standard plate. Then, measurement was conducted by placing a sample image 
on the sample table, and further by superposing thereon three sheets of 
white paper. The values indicated on the display were read in % units. At 
this time, the S-S/10 changeover switch is set to the S side and the 
angle-sensitivity changeover switch is set to 45-60. 
EXAMPLE 14 
A non-magnetic toner (non-magnetic color toner) having a particle size 
distribution as shown in Table 8 was prepared in the same manner as in 
Example 13 except that 1.0 wt. parts of C.I. Solvent Red 52 (magenta 
colorant) and 0.9 wt. parts of C.I. Solvent Red 49 were used instead of 
the 3.5 wt. parts of C.I. Pigment Yellow 17 (yellow colorant). 
By using the thus obtained magenta toner in the same manner as in Example 
13, an evaluation was conducted in the same manner as in Example 13. 
As a result, high-quality magenta images excellent in clearness and gloss 
were stably obtained, as shown in Table 9. 
EXAMPLE 15 
A cyan toner (non-magnetic color toner) having a particle size distribution 
as shown in Table 8 was prepared in the same manner as in Example 13 
except that 5.0 wt. parts of C.I. Solvent Blue 15 (cyan colorant) were 
used instead of the 3.5 wt. parts of C.I. Pigment Yellow 17 (yellow 
colorant). 
By using the thus obtained cyan toner in the same manner as in Example 13, 
an evaluation was conducted in the same manner as in Example 13. 
As a result, high-quality cyan images excellent in clearness and gloss were 
stably obtained, as shown in Table 9. 
EXAMPLE 16 
A black toner (non-magnetic color toner) having a particle size 
distribution as shown in Table 8 was prepared in the same manner as in 
Example 13 except that a mixture (black colorant) of 1.2 wt. parts of C.I. 
Pigment Yellow 17, 2.8 wt. parts of C.I. Pigment Red 5 and 1.5 wt. parts 
of C.I. Pigment Blue 15 was used instead of the yellow colorant used in 
Example 13. 
By using the thus obtained black toner in the same manner as in Example 13, 
an evaluation was conducted in the same manner as in Example 13. 
As a result, high-quality black images excellent in clearness and gloss 
were stably obtained, as shown in Table 9. 
COMATIVE EXAMPLE 11 
A yellow toner having a particle size distribution as shown in Table 8 was 
prepared in the same manner as in Example 13, except that two fixed-wall 
type wind-force classifiers used in Example 13 were used for the 
classification instead of the combination of the fixed-wall type 
wind-force classifier and the multi-division classifier used in Example 
13. 
In the thus prepared yellow non-magnetic toner of Comparative Example 11, 
the percentage by number of the non-magnetic toner particles of 5 microns 
or smaller was smaller than the range thereof defined in the present 
invention, the volume-average particle size was larger than the range 
thereof defined in the present invention, and the value of (% by number 
(N))/(% by volume (V)) of the non-magnetic toner particles of 5 microns or 
smaller was larger than the range thereof defined in the present 
invention, whereby the conditions required in the present invention were 
not satisfied. 
By using the thus obtained yellow toner, a two-component developer was 
prepared in the same manner as in Example 13 and was subjected to an image 
formation evaluation under similar conditions as in Example 13. 
In the resultant images, the toner particles remarkably protruded from the 
latent image formed on the photosensitive member as compared with that in 
Example 13, the sharpness was lacking and the resolution was 4.0 lines/mm 
which was somewhat inferior to that obtained in Example 13. Further, toner 
consumption was large. 
Further, in comparison with Example 13, the cover-up in the inner portion 
was insufficient when compared with that in the edge portion with respect 
to a solid image. Moreover, the cover-up of toner particles was ununiform 
in some portions of the inner portion of the solid image, and the 
resultant image was somewhat inferior in gloss. 
COMATIVE EXAMPLE 12 
A magenta toner having a particle size distribution as shown in Table 8 was 
prepared in the same manner as in Example 13, except that two fixed-wall 
type wind-force classifiers used in Example 14 were used for the 
classification instead of the combination of the fixed-wall type 
wind-force classifier and the multi-division classifier used in Example 
14. 
By using the thus obtained magenta toner in the same manner as in Example 
13, an evaluation was conducted in the same manner as in Example 13. 
As a result, as shown in Table 9, there were obtained magenta images which 
were inferior to those obtained in Example 14 because the line resolution 
and gloss were somewhat poor and the image density in the solid image 
portion was low. 
COMATIVE EXAMPLE 13 
A cyan toner having a particle size distribution as shown in Table 8 was 
prepared in the same manner as in Example 15, except that two fixed-wall 
type wind-force classifiers used in Example 15 were used for the 
classification instead of the combination of the fixed-wall type 
wind-force classifier and the multi-division classifier used in Example 
15. 
By using the thus obtained magenta toner in the same manner as in Example 
13, an evaluation was conducted in the same manner as in Example 13. 
As a result, as shown in Table 9, there were obtained cyan images which 
were inferior to those obtained in Example 15 because the line resolution 
and gloss were somewhat poor and the image density in the solid image 
portion was low. 
COMATIVE EXAMPLE 14 
A black toner having a particle size distribution as shown in Table 8 was 
prepared in the same manner as in Example 16, except that two fixed-wall 
type wind-force classifiers used in Example 16 were used for the 
classification instead of the combination of the fixed-wall type 
wind-force classifier and the multi-division classifier used in Example 
16. 
By using the thus obtained magenta toner in the same manner as in Example 
13, an evaluation was conducted in the same manner as in Example 13. 
As a result, as shown in Table 9, there were obtained black images which 
were inferior to those obtained in Example 16 because the line resolution 
and gloss were somewhat poor and the image density in the solid image 
portion was low. 
EXAMPLE 17 
By using the respective two-component developers obtained in Examples 
13-16, multi-color and full-color copy images were obtained in the same 
manner as in Example 13 except that a full-color mode was used instead of 
the monocolor mode. The thus obtained color images were evaluated in the 
same manner as in Example 13. 
As a result, as shown in Table 9, there were stably obtained clear 
full-color copy images which faithfully reproduced the original full-color 
chart. Particularly, because cover-up of the toner particles was uniform 
in the inner portion of a solid image, no& only the gloss but also the 
color mixing characteristic was enhanced, whereby full-color images 
excellent in color reproducibility were obtained. 
COMATIVE EXAMPLE 15 
By using the respective two-component developer obtained in Comparative 
Examples 11-14, multi-color and full-color copy images were obtained in 
the same manner as in Example 17 except that a full-color mode was used 
instead of the monocolor mode. The thus obtained color images were 
evaluated in the same manner as in Example 17. 
As a result, there were stably obtained clear full-color copy images which 
substantially faithfully reproduced the original full-color chart. 
However, it was observed that cover-up of the toner particles was 
ununiform in some portions of the inner portion of a solid image. Further, 
these images were poor in gloss and color reproducibility. 
TABLE 8 
__________________________________________________________________________ 
Particle size distribution of toner 
% by number 
% by volume 
% by number 
Volume-average 
(% by number)/(% by 
of particles 
of particles 
of particles 
particle size 
volume) of particles 
.ltoreq.5 .mu.m 
.gtoreq.16 .mu.m 
of 8-12.7 .mu.m 
(.mu.m) .ltoreq.5 .mu.m 
__________________________________________________________________________ 
Example 
13 34 0 16 7.9 3.4 
14 34 0 17 7.9 3.4 
15 35 0 17 7.9 3.4 
16 34 0 17 7.9 3.5 
Comparative 
Example 
11 13 2.3 46 12.2 34 
12 12 2.3 48 12.3 39 
13 13 2.3 46 12.3 42 
14 13 2.3 46 12.2 34 
__________________________________________________________________________ 
TABLE 9-1 
______________________________________ 
Initial stage 
Dmax Dmax 
(5 mm (solid image Resolution 
diameter) 
portion) Gloss (lines/mm) 
______________________________________ 
Example 
13 1.50 1.50 19.6% 5.0 
14 1.49 1.51 24.4% 5.0 
15 1.47 1.49 21.9% 5.0 
16 1.52 1.52 20.3% 5.0 
17 1.52 1.53 22.1% 4.5 
Comparative 
Example 
11 1.52 1.42 7.4% 4.0 
12 1.49 1.42 16.0% 4.0 
13 1.50 1.42 10.7% 4.0 
14 1.53 1.41 12.2% 4.0 
15 1.50 1.41 15.5% 3.6 
______________________________________ 
TABLE 9-2 
__________________________________________________________________________ 
After 2,000 sheets of image formations 
Dmax Dmax Resolution 
Toner consumption 
(5 mm dia.) 
(Solid image portion) 
Gloss 
(lines/mm) 
(g/one sheet) 
__________________________________________________________________________ 
Example 
13 1.53 1.53 20.7% 
5.0 0.023 
14 1.52 1.52 25.5% 
5.0 0.022 
15 1.48 1.50 23.0% 
5.0 0.022 
16 1.54 1.55 21.4% 
5.0 0.021 
17 1.49 1.49 23.2% 
4.5 0.024 
Comparative 
Example 
11 1.52 1.41 7.9% 
4.0 0.046 
12 1.50 1.40 15.9% 
4.0 0.049 
13 1.47 1.40 10.9% 
4.0 0.042 
14 1.47 1.39 12.5% 
4.0 0.043 
15 1.53 1.40 15.6% 
3.6 0.046 
__________________________________________________________________________