JPH01281475A - Image forming method - Google Patents

Abstract

PURPOSE:To prevent the stripe pattern of an image from occurring in using a photosensitive body whose constitution of layer and production are not complicated by making coherent light incident on the part of curved surface whose radius of curvature is <=20mm in an electrophotographic photosensitive body. CONSTITUTION:A belt-like photosensitive body 4 is electrostatically charged by an electrostatic charger 6 and bent with a roller 5. The coherent light 7 is made to be cast to the part of curved surface of the bent part. At such a time, the smaller radius of the roller 5 is more desirable. Namely, the part obtained by forming the curved surface whose radius of curvature is <=20mm is provided on the electrophotographic photosensitive body and the coherent light is made to be cast to said part. Thus, unevenness of image density caused by interference does not occur in the copied image obtained by reversal development.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an image forming method in which an electrophotographic photoreceptor is irradiated with coherent light to form an electrostatic image and visualized. The present invention relates to an image forming method that prevents the occurrence of striped patterns in images.

Conventional technology In the electrophotographic process, the surface of an electrophotographic photoreceptor is normally charged, imagewise exposed, the formed electrostatic image is developed with toner, and the toner image is transferred and fixed onto transfer paper to form a projected object. (q
In this process, the photoreceptor is subjected to processes such as neutralization and cleaning as necessary, and then moves on to the next close-up cycle.

In recent years, laser printers that use an electrophotographic process using laser light as a light source have been put into practical use as printers that visualize digital signals.

In this case, an image forming method is used in which the photoreceptor is irradiated with a laser beam modulated by image information, but since the laser beam is coherent, multiple reflections occur inside the photosensitive layer, which tends to cause interference. .

On the other hand, electrophotographic photoreceptors can be divided into those using inorganic photoconductors and those using organic photoconductors, but those using the latter are non-polluting, high productivity, low cost, etc. It has become widely used because of its advantages.

However, among organic photoconductors, substances that absorb light and generate electric charge have poor charge retention ability, and conversely, materials that have good charge retention ability and are excellent in film forming properties generally have poor photoconductivity. It has the disadvantage of being low.

In order to solve this problem, it is necessary to make the photosensitive layer a laminated type in which the functions are separated into a charge generation layer that absorbs light and generates charges, and a charge transport layer that transports the charges. However, in the case of such a laminated photosensitive diagram, there is a problem that interference is likely to occur when coherent light is used.

This will be explained with reference to FIG. FIG. 2 shows that the photosensitive layer on the substrate 3 is a charge generating layer 1. 2 is a cross-sectional view of a laminated electrophotographic photoreceptor in which functions are separated into a charge transport layer 2 and a charge transport layer 2. FIG.

The luminous flux of the incident light enters the photosensitive layer with a certain magnitude, but among the components 92 and 13, the component of the light reflected from the charge generation layer surface or the substrate surface among 21 is superimposed,
interference is caused. Due to interference, the intensity of light is either strengthened or weakened compared to the original incident light. Therefore,
The intensity of light incident on the charge generation layer is 91', J)2'
, Q3' are different from each other, resulting in a striped pattern in the image. Note that since the charge generation layer is generally thin, some components may pass through without being absorbed therein, causing interference. In reality, complex interference is caused by the structure of the layers in addition to the photosensitive layer shown in FIG.

As a means to prevent such interference, for example,
JP-A-57-165844 discloses providing a light scattering and reflective layer on the surface of a substrate.

Furthermore, Japanese Patent Laid-Open No. 57-165845 discloses providing a light absorption layer on the surface of the substrate. On the other hand, Japanese Patent Laid-Open No. 58-171057 discloses various methods such as roughening the surface of the substrate.

Problems to be Solved by the Invention In these conventional techniques, the manufacturing method of the photoreceptor is complicated, such as by providing a light-scattering reflective layer or a light-absorbing layer or roughening the surface of the substrate. There was also a drawback that the structure of the photoreceptor was complicated.

The present invention aims to solve the above-mentioned problems in the conventional technology.

That is, an object of the present invention is to provide an image forming method that does not cause a striped pattern on an image by using a photoreceptor having a layer structure and a manufacturing method that are not inferior.

In order to solve the problem and prevent the interference of the working light, it is effective to reduce the components of the reflected light that contribute to the interference. The photoreceptor is exposed imagewise to reduce interference.

That is, in the present invention, an electrophotographic photoreceptor having a photosensitive layer on a substrate is charged, and then imagewise modulated coherent light is irradiated to attenuate the surface potential of the photosensitive layer to form an electrostatic image. In an image forming method in which a visible image is formed by a reversal development method in which a portion of low potential is developed and a portion of high potential is not developed after formation, a radius of curvature 2 in an electrophotographic photoreceptor is used.
It is characterized in that the coherent light is incident on a curved surface portion of 0 m or less.

The present invention will be explained with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a portion where an electrophotographic photoreceptor forms a curved surface. The incident light is a luminous flux Ll, L2, L3 of a certain size.
The light is incident on the photosensitive layer.

Since the base body 3 has a curved surface, light Ll', L2 that passes through the charge transport layer 2 and the charge generation layer 1 that constitute the photosensitive layer
', L3' becomes reflected light on the substrate surface and diverges. Therefore, since the angles of the incident light and reflected light are shifted, interference becomes less likely to occur. That is, reflected light L2 of incident light L2
'' and the incident light L3 are at different angles, so they are less likely to interfere with each other.

As mentioned above, the divergence of reflected light increases as the curvature of the curved surface increases, so interference becomes less likely to occur as the curvature increases, but it is impossible to completely eliminate interference.

Incidentally, even if the light incident on the photosensitive layer undergoes multiple reflections within the photosensitive layer, causing interference and the light intensity to fluctuate, the fluctuation width of the surface potential of the image-exposed area will be within ±.
It has been found that if the voltage is within 20 V, when the electrostatic charge that is formed is reversely developed, image density unevenness due to interference hardly becomes a problem in the obtained copy image.

Therefore, in the present invention, the variation width of the surface potential of the image exposure part is ±2.
In order to keep the voltage within 0V, the curvature of the image-exposed area of the photoreceptor is increased.If the radius of curvature is 20 mm or less, the fluctuation width of the surface potential of the image-exposed area will be within ±20V. be. Therefore, in the present invention, a portion forming a curved surface with a radius of curvature of 20# or less is created on the electrophotographic photoreceptor, and coherent light is irradiated to that portion, thereby making it possible to obtain the desired result by reversal development. In the copied image, image density unevenness due to interference no longer occurs.

Next, the electrophotographic photoreceptor used in the present invention will be explained.

As an electrophotographic photoreceptor, either one using an inorganic photoconductor or one using an organic photoconductor can be used, but the present invention is preferably applicable mainly to those using a laminated photoconductor. It is an electrophotographic photoreceptor with When an organic photoconductor is used, it is advantageous because it has advantages such as non-pollution, high productivity, and low cost.

The charge generation layer constituting the laminated photosensitive layer includes trigonal selenium, amorphous selenium, 5e-Te alloy, 5e-AS alloy, heptanoazo or polyazo pigment, polycyclic quinone pigment, perylene pigment, indigo pigment, bis Charge-generating substances such as benzimidazole pigments, phthalocyanine pigments, cypcridone pigments, biryllium compounds, squalium compounds, cyanine compounds, quinocyanine compounds, trimethine compounds, and azulenium compounds may be added to polyester, polystyrene, cellulose fatty acid ester, boron, etc. as necessary. It is formed by dispersing it in a solution of calculus resin such as (meth)acrylic ester resin, polyvinyl butyral, vinyl chloride-vinyl acetate copolymer, etc., and applying it. The thickness of the charge generation layer is preferably in the range of 0.05 to 5 μm.

In the case of an electrophotographic photoreceptor that uses semiconductor laser light, phthalocyanine or a squareium compound is preferable as the charge generating substance.

The phthalocyanine may be a phthalocyanine which is a photoconductor element, and may be a metal-free phthalocyanine, a metal phthalocyanine, or a mixture thereof. Metal phthalocyanines include copper, silver, beryllium, magnesium, calcium, zinc, cadmium, barium, mercury, aluminum, gallium, indium, lanthanum, neodymium, (nomarium, europium, gadolinium, dysprosium, holmium, sodium, lithium, Ytterbium, lutetium, titanium, tin, octunium, lead, thorium, vanadium, antimony, chromium, molybdenum, uranium 1. Manganese, iron, cobalt, nickel, rhodium, palladium, osmium, platinum, etc. Also, phthalocyanine Instead of a metal atom, a metal halide or a metal hydride having a valence of 3 or more may be present at the center.
Phthalocyanines are known to have various crystal systems, such as α-type, β-type, γ-type, δ-type, ε-type.
Crystal systems such as type and X type are used.

As a squalium compound, JP-A-59-1257
No. 35, No. 60-128452-5, No. 60-131
Examples include those described in Publication No. 538 and the like.

The charge transport layer contains a charge transport substance such as an aromatic tertiary amine compound, a godracine compound, a pyrazoline compound, an oxazole compound, an oxadiazole compound, a stilbene derivative, or a carbazole compound, and if necessary, a charge transport substance such as polycarbonate, polyarylate, Formed by dissolving them together with a film-forming resin such as polyester, polystyrene, styrene-7-crylonitrile copolymer, polysulfone, polymethacrylic acid esters, and styrene-methacrylic acid ester copolymer in a solvent that can dissolve them. be done.

The thickness of the charge transport layer is approximately 5 to 50 mm.

As a substrate, an electrically conductive support such as aluminum,
Copper, iron, zinc, nickel, etc. gold, glazed drums, and aluminum, copper, gold, silver, platinum, palladium, titanium, nickel-chromium, stainless steel, copper-indium, etc. on sheet, paper, plastic or glass. or deposit a conductive metal compound such as indium oxide or tin oxide, or laminate a metal foil, or deposit carbon black, indium oxide, tin oxide-dispersed antimony powder,
Known materials such as drum-shaped, sheet-shaped, or plate-shaped materials can be used, which are conductive-treated by dispersing metal powder or the like in a binder resin and applying the coating.

A barrier layer may be provided on the substrate. The barrier layer is designed to prevent unnecessary charge injection from the substrate.
It has the effect of increasing the chargeability of the photosensitive layer and improving image quality. Furthermore, it also has the effect of improving the adhesion between the photosensitive layer and the substrate. Materials constituting the barrier layer include polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl lysine,
Cellulose needles, cellulose esters, polyamide, polyurethane, glutinous acid, pyratine, polyglutamic acid, lees (min., starved acetate-1~, amino F2)
Examples include powder, polyacrylic acid, polyacrylamide, etc. The resistivity of these materials is 105-1014 Ωcm
degree is preferred. The film thickness of the barrier diagram is set to about 0.05 to 2 μm.

In the electrophotographic photoreceptor of the present invention, in order to make the radius of curvature of the portion into which the coherent light is incident not more than 20#, if the electrophotographic photoreceptor is a cylindrical body, the outer diameter should be set to 40# or less. Just make it into something. Further, when the electrophotographic photoreceptor is a belt, it is sufficient to bend the belt so as to form a curved surface with a radius of curvature of 20 seconds or less.

FIG. 3 shows a sectional view of essential parts when the electrophotographic photoreceptor is a bell body. The belt-shaped photoreceptor 4 is charged by a charger 6 and bent by a roller 5. The structure is such that the coherent light 7 is irradiated onto the curved surface portion of this 1 m curved section. The radius of the roller 5 is preferably small. When the electrophotographic photoreceptor is a belt, the radius of curvature can be made considerably smaller by using rollers, so a belt may be more advantageous than a cylindrical body.

By the way, it is preferable that the fluctuation width of the surface potential due to interference be as small as possible, but in order to reduce the fluctuation width of the potential, 1
) Increase the amount of light absorbed by the photosensitive layer (charge generation layer) and reduce reflected light; 2) Increase the sensitivity of the photosensitive layer and accelerate light attenuation to enable use in the low potential saturation region; 3) Examples include improving the optical attenuation curve of the photosensitive layer and flattening the sensitivity of the low potential saturated flO region. The image forming method of the present invention is more advantageous when used in combination with a means for reducing the potential fluctuation range as described above. For example, if you use a flat part of the surface potential like the part C in the light attenuation curve of an electrophotographic photoreceptor (not shown in FIG. Fluctuations will be smaller.

Examples Example 1 An aluminum vibrator of 40 #φ x 260 sφ was used as the base. To this, copolymerized nylon resin (product name:
A methanol/butanol solution of CH3000 (manufactured by Toshi) was applied using a ring coater to form an attached 0.7-layer barrier layer.

Next, 3 parts of vanadyl phthalocyanine was dispersed in 70 parts of a 10% cyclohexanone solution of a polyester resin (trade name: PE100, manufactured by Gutdeyer Chemical Co.).The dispersion operation was performed by ball milling the mixture using an 8#φ pole. This was done by mixing for 4 hours at a
- 10 parts of butanone was added to prepare a coating solution, which was coated onto the barrier layer using a ring coater to form a charge generation layer with a film droplet thickness of 0.4 μm.

A charge transport layer was formed on the formed charge generation layer. That is, N,N'-Sifinyl-N.

4 parts of N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine was used as a charge transport material, and dissolved in 40 parts of monochlorobenzene together with 6 parts of polycarbonate Z resin. The solution was applied using a dip coating device at a pulling speed of 110 m/min. 110℃
was dried for 1 hour to form a charge transport layer with a thickness of 20,
An electrophotographic photoreceptor was obtained.

This electrophotographic photoreceptor was charged to -500 V, and then evaluated using a printer having electrophotographic processes such as imagewise exposure, reversal development with a negatively charged developer, transfer, and cleaning with a rubber electrode.

First, a light attenuation curve of surface potential was determined using an incoherent light source as an exposure light source. The results are shown as curve A in FIG. In FIG. 4, the vertical axis represents the surface potential, and the horizontal axis represents the light intensity.

Next, imagewise exposure was performed by image light scanning using a semiconductor laser having a wavelength of 785 nm and an intensity of 7 ergs/7 on the surface of the photoreceptor as an exposure light source. When we measured the potential of the irradiated part in this case, it was -85 to -120v.
There was a change in When the formed electrostatic image was reversely developed to obtain a copy image, almost no striped pattern was observed.

Comparative Example 1 As a substrate, 60. Using an aluminum vibrator of φx260 gφ, a photosensitive layer similar to that of Example 1 was formed by 8&p; to produce an electrophotographic photoreceptor. A total of one stack of this electrophotoreceptor was prepared using a printer having the same electrophotographic process as in Example 1. When light was irradiated with the same laser beam as in Example 1 and the potential was measured, a fluctuation of -80 to -125V was observed. When the formed electrostatic image was developed and a copy image was created,
A striped pattern appeared in the black background area, and the image quality was inferior to that in Example 1.

Example 2 The thickness of the N charge generation layer was 0.3 m, and the thickness of the charge transport layer was 23 m.
An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the light attenuation curve was measured. The results are shown in Figure 4 as curve B.Next, when the photoreceptor surface was irradiated with a semiconductor laser beam of intensity 10erQS/C chips and the potential was measured, it was found that -85
There was a fluctuation of ~-120V. When the formed electrostatic image was reversely developed to obtain a copy image, almost no striped pattern was observed.

Example 3 Using an aluminum pipe of 30 mφ x 260 sφ as a substrate, a photosensitive layer similar to that in Example 1 was formed to produce an electrophotographic photoreceptor. This electrophotographic photoreceptor was evaluated using a printer having the same electrophotographic process as in Example 1. Strength on photoreceptor surface 8
ergs,” Irradiate with a semiconductor laser beam of “Cm” at 1 no.
When the potential was measured, there was a fluctuation of -120 to -150V. When the formed electrostatic image was developed to create a bee image, almost no striped pattern was observed.

Effects of the Invention In the present invention, since coherent light is incident on a curved surface portion with a radius of curvature of 20 m or less on an N-chi photoreceptor, a static N image is formed using the coherent light, and a static N image is formed by reversal development. - When the visible image is converted to (q), a fringe pattern due to interference does not occur in the image. Therefore, a bee image of excellent image quality can be obtained.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams for explaining the generation mechanism of striped patterns due to interference, and FIG. 3 shows that the electrophotographic photoreceptor is
FIG. 4 is a sectional view of the main parts for explaining the present invention in the case where the electrophotographic photoreceptor is used in the present invention. DESCRIPTION OF SYMBOLS 1... Charge generation layer, 2... N charge transporting layer, 3... Substrate, 4... Pel 1-I photoreceptor, 5... Roller, 6
...Charger, 7...Coherent light. Patent applicant Fuji Xerox Co., Ltd. Agent
Patent attorney Tsuyoshi Watanabe l+1L2L3 Mitsuru 1f (arp/~) Figure 4

Claims (3)

[Claims] (1) After charging an electrophotographic photoreceptor having a photosensitive layer on a substrate, and then irradiating imagewise modulated coherent light to attenuate the surface potential of the photosensitive layer to form an electrostatic image, In an image forming method in which a visible image is formed by a reversal development method in which areas with a low potential are developed and areas with a high potential are not developed, the coherent light is applied to a curved surface area of an electrophotographic photoreceptor with a radius of curvature of 20 mm or less. An image forming method characterized in that: (2) The image forming method according to claim (1), wherein the electrophotographic photoreceptor is a cylindrical body having an outer diameter of 40 mm or less. (3) The electrophotographic photoreceptor is a belt body, and the radius of curvature is 20
The image forming method according to claim 1, wherein a curved surface portion having a diameter of mm or less is formed, and the curved surface portion is irradiated with coherent light.