JP2002240347A - Write method of imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an effect of reducing a dot position change effective by setting a shape and a size of an irradiation luminous flux for writing in an appropriate range. SOLUTION: There is provided a latent image carrier in which islands 1 of a high light sensitivity region are periodically arranged in a low light sensitivity region in a relation between a size of a toner image 3 and the high light sensitivity region, when light is irradiated only to a part of the islands 1 of the high light sensitivity region or the like. The toner image 3 is formed by transferring and fixing toner from the latent image carrier onto a paper or a film. In a method for writing latent images of an imaging apparatus which irradiates the latent image carrier of a digital electrophotographic apparatus with the luminous flux, an area Si of the island of the high light sensitivity region and an area St of the corresponding toner image on the paper or the film hold a comparative relation of Si<=St. Therefore, appropriate exposure and writing are enabled to the mask latent image carrier having islands of the high light sensitivity region periodically arranged in the low light sensitivity region, and the imaging apparatus having a high image quality without a dot position deviation can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a writing method for an image forming apparatus, for example, to an image forming apparatus using electrophotography, and more particularly to a writing method for an image forming apparatus using a laser light source or an LED array.

[0002]

2. Description of the Related Art Conventionally, a writing method of an image forming apparatus is generally applied to a copying machine, a facsimile, a printer, and the like, and measures are taken to cope with dot position fluctuations during writing / latent image formation.

[0003] The above-mentioned dot position fluctuations during writing / latent image formation cause image quality defects such as banding and vertical streak defects, and also play a role in deteriorating the granularity of images. And at least in the present situation, it is a harmless phenomenon. The conventional response to this phenomenon is mainly to reduce the speed fluctuations of the drive system and the writing / scanning optical system, and more precisely, to dynamically correct the drive signal by improving the accuracy and rigidity of the scanning and drive system components. The existing printers have been fairly successful. However, further improvements are needed and are being studied in view of further increasing the resolution of electrophotographic printing machines in the future.

[0004] Example 1 of the prior application similar to the present invention in the technical field
There is JP-A-63-52148. The gist of the contents of the present invention is that a layer having a filter function is provided on the photoreceptor in a mosaic form, each mosaic is isolated by a light shielding layer, and image exposure (analog) and development corresponding to each color are repeated. Thus, a color image without color shift is obtained.

As another countermeasure against dot displacement, for example, Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent Application Laid-Open No. 52591, a latent image carrier in which members having different characteristics such as photosensitivity and surface properties are arranged discretely and periodically is used. This makes it possible to prevent the dot position of the latent image from fluctuating even if the dot position of the light beam is shifted to some extent during writing. The gist of the contents of Japanese Patent Application Laid-Open No. 11-52591 is that the latent image carrier has a lattice-like structure in which light sensitivity and surface properties are changed, so that even if the position of the exposure beam is slightly displaced, Thus, the exposure position is regulated, so that a latent image with high dot position accuracy can be formed.

In another prior art example 3, there is an example of a lattice pattern in which a CGL dye is selectively destroyed in an arbitrary pattern by irradiation of ultraviolet rays or the like, and a region having changed light sensitivity is created with high precision. .

Various patterns such as those illustrated in FIG. 2 used in the description of the present invention can be considered for such a latent image carrier. As shown in FIG. 2, for example, as a specific method of manufacturing the latent image carrier, in the above-mentioned prior art example 3, high energy rays such as ultraviolet rays are irradiated in an arbitrary pattern to destroy the CGL dye of OPC. Thus, a method of creating a region in which light sensitivity has changed with an arbitrary pattern with high accuracy is disclosed.

However, in this method, if a pattern is formed by scanning a beam, it is easy to form a pattern such as a square lattice shown in FIG. If it is desired to obtain a spatial frequency distribution of the latent image as uniform as possible in all directions of the surface of the latent image carrier, the patterns shown in FIGS. 2C to 2E are suitable.

In addition to the above, a pattern in which the high light sensitivity region and the low light sensitivity region are arranged in a parallel line is also conceivable. However, the present invention is limited to the case where there is an island in the high light sensitivity region in the low light sensitivity region, and this is not the target.

[0010]

However, in the conventional digital electrophotography of the prior art, in order to reduce the dot position variation using the latent image carrier, it is necessary to perform the above-described various shapes on the pattern. It is necessary to put the shape and size of the writing light beam in an appropriate range, but there is a problem that such a range has not been specifically considered in the past.

According to the present invention, the shape and size of a writing light beam for writing into a latent image carrier in which islands of a high light sensitivity region are periodically arranged in a low light sensitivity region are set within an appropriate range. It is an object of the present invention to provide a writing method of an image forming apparatus which makes the effect of reducing positional fluctuation effective.

[0012]

In order to achieve the above object, a writing method of an image forming apparatus according to the present invention is directed to a latent image carrier in which islands of a high light sensitivity region are periodically arranged in a low light sensitivity region. A latent image writing method of an image forming apparatus that irradiates a light beam to a latent image carrier of a digital electrophotographic apparatus that forms a toner image by transferring and fixing toner from the latent image carrier onto paper or a film, The feature is that the area Si of the island in the high light sensitivity region and the area St of the toner image on paper or film corresponding to the island have a relation of comparison of Si <= St.

[0013] The shape and size of the irradiation range of the light beam to be written only on the one high-sensitivity island is such that when compared with the shape and size of the high-sensitivity region on the surface of the latent image carrier, the two overlap. One of the islands in the high light sensitivity region has a shape and a size that fall within the “irradiation range equal to or more than the minimum irradiation amount capable of forming a toner image on paper or film”, and the surface of the latent image carrier has When comparing the shape and size between the island in the high-sensitivity region and the irradiation light flux, the two are superimposed, and the irradiation in the high-sensitivity region is equal to or higher than the irradiation amount to obtain a half-maximum density of the maximum reflection density of the toner image. The shape and the size should be within the range "."

Further, the shape and size of the irradiation range of the light beam to be written only on one high-sensitivity island is smaller than the shape and size of the high-sensitivity region on the surface of the latent image carrier and the distribution in the low-sensitivity region. When the two are overlapped, the islands of three or more high-sensitivity areas aligned on the same straight line and the "irradiation range not less than the minimum irradiation amount capable of forming a toner image on paper or film" do not overlap. The shape and size of the irradiation range of the light beam to be written only on one high-sensitivity island is the shape and size of the high-sensitivity region and the low-sensitivity region on the surface of the latent image carrier. When compared with the distribution, the two are superimposed, and three or more high-sensitivity region islands arranged on the same straight line and "irradiation range equal to or more than half the minimum irradiation amount capable of forming a toner image on paper or film" However, it is preferable that the shape and the size do not overlap.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a writing method for an image forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 to FIG. 5 show an embodiment of a writing method of the image forming apparatus according to the present invention.

FIG. 1 shows an example of the relationship between the high light sensitivity area and the size of the toner image. In this example, FIG.
Is an example of the relationship between the high light sensitivity area and the size of the toner image when light is applied to the entire high light sensitivity area. FIG.
(B) is an example of the relationship between the high light sensitivity region and the size of the toner image when light is irradiated to only a part of the high light sensitivity region. In FIG. 1 showing this relationship, the island 1 in the high light sensitivity region
And a toner image 3 on paper or film.

FIG. 2 shows an example of a pattern in which regions having different light sensitivities are arranged on the latent image carrier. In this example, FIG. 2A is an example of a rectangular lattice pattern. FIG.
(B) is an example of a pattern of a simple rectangular array of circular high light sensitivity areas. FIG. 2C is an example of a pattern of a close-packed arrangement in a circular high light sensitivity area. FIG. 2D is a pattern example of a close-packed arrangement in a hexagonal high-sensitivity region. FIG. 2 (e)
Is a pattern example of a sparse array of hexagonal high photosensitivity regions (a configuration in which the high photosensitivity regions are sandwiched between straight lines in three directions). FIG. 2 shows an island 1 in a high light sensitivity region and a low light sensitivity region 2.

FIG. 3 shows an example of a light beam irradiation pattern. In this example, FIG. 2A is an example of a stationary pattern of a circular light beam. FIG. 2B is an example of a stationary pattern of an elliptical light beam. FIG. 2C is an example of a pattern in which a circular or elliptical light beam is moved in one direction.

A mask latent image carrier having a pattern shown in FIG. 2B was prepared, and the following examination was conducted. Study 1 below
Is a 1-by-1 pattern printing experiment (subject: claims 1 to 1)
5).

A mask latent image carrier having the pattern shown in FIG. 2B was prepared, and a halftone image at every other dot, that is, a so-called 1-by-1 image was output. A raster image is formed on paper by reducing the raster scan speed to about 100 line / sec, which is 1/10 or less of the normal, and using the irradiation amount as a parameter in each of the three patterns shown in FIGS. 3 (a) to 3 (c). The presence or absence of banding and vertical stripe unevenness was confirmed. FIG. 3 shows the equal light irradiation energy beam 4. The results are shown in Table 1.

Here, the stationary luminous flux of the used light source is shown in FIG.
As shown in FIG. 3 (b), the shape is long in the sub-scanning direction. In the experiment, irradiation with the shape shown in FIG. 3 (c) was performed by oscillating a plurality of light pulses at a constant pulse cycle. The irradiation amount is changed by changing the pulse width.

The toner image area (St) is obtained by shifting the center position of the light beam with respect to the island in the high-sensitivity region of the latent image carrier by about 2 dots in each of the main scanning direction and the sub-scanning direction.
The largest area obtained among them was defined as St. In the table, St is represented by a value obtained by dividing the area (Si) of the island in the high light sensitivity region. If this value exceeds “1”, the value falls within the range defined in claim 1.

As a method for confirming the presence or absence of banding and vertical stripe unevenness, the center position of the light beam with respect to the island in the high-sensitivity region of the latent image carrier is shifted by about 2 dots in each of the main scanning direction and the sub-scanning direction. The test was performed by visually checking whether or not banding and vertical stripe unevenness occurred therein.

[0024]

[Table 1]

Investigation 2 relates to the relationship between the shape and size of the light beam irradiation range and the shape and size of the island in the high light sensitivity region (subject: claims 2 to 5). Solid exposure was performed on the mask latent image carrier obtained in Study 1 above, and the relationship between the light irradiation amount and the reflection density of the toner image was obtained. The relationship shown in the graph of FIG. 4 was obtained. FIG. 4 shows the relationship between the distribution of islands in the high light irradiation area and the light irradiation area 5. In this relationship, FIG. 4 (a) has the relationship defined in claims 2 and 3, and FIG. 4 (b) has the relationship defined in claims 4 and 5.

FIG. 5 is a graph showing the relationship between the light irradiation amount and the reflection density. In relation to the reference numerals in FIG. 5, a minimum irradiation amount 6 for forming a toner image and an irradiation amount 7 for obtaining a half value of the maximum reflection density of the toner image are shown.

Next, the irradiation range of the light beam used for writing in the study 1 is measured using a photosensitive film, and compared with the solid light irradiation amount, the irradiation range defined in claims 2 to 5 is determined. , The relationship with the high light sensitivity region was determined. Table 2 shows the results.

The contents of the symbols in Table 2 are shown below. L _L : Irradiation range equal to or higher than the minimum irradiation amount capable of forming a toner image; L _H : Irradiation range equal to or higher than the irradiation amount to obtain half the maximum reflection density of the toner image; L _HL : Minimum irradiation amount capable of forming a toner image Irradiation range of 以上 or more, I _H : island in high light sensitivity region.

[0029]

[Table 2]

In the following description, "a latent image carrier in which islands of a high light sensitivity region are periodically arranged in a low light sensitivity region" will be referred to as a mask latent image carrier.

(Embodiment 1) If Si <= St is not satisfied no matter how the writing position is changed, since the state is as shown in FIG. 1B, the dot position shift due to the use of the mask latent image carrier is performed. No reduction effect can be obtained.

Example 2 The above range was narrowed down from another angle by directly comparing the shape and size of the writing light beam irradiation range with the shape and size of the island in the high light sensitivity region.

(Example 3) A narrower range was narrowed down more preferably than in Example 3. The reason why the "irradiation range equal to or more than the radiation amount at which the half value of the maximum reflection density of the toner image is obtained" is selected because the range is most sensitively changed by the fluctuation of the radiation amount.

(Embodiment 4) Since the above three embodiments define the minimum range, the maximum irradiation range for one dot is defined. Exceeding this range will result in irradiating two or more high-sensitivity areas regardless of the shape, size, and distribution of the high-sensitivity areas.

(Embodiment 5) When a light beam is applied to every other island in the high light sensitivity area, at least two adjacent islands of the light beam overlap each other to irradiate the island between them. In order to prevent a toner image from being formed with this light, it is necessary to define an irradiation range with a light amount of less than half of the light amount in the fourth embodiment.
Since superposition of three or four light beams is also conceivable,
More preferably, the irradiation range of the light beam can be limited to 1/3 and 1/4 of the light amount of the fourth embodiment.

In the embodiments 2 to 5, the determination of the "minimum irradiation amount capable of forming a toner image" and the "half value of the maximum reflection density" used in each of the embodiments is based on a sufficiently large size of the shadow mask latent image carrier. The area is irradiated with light, and the area is derived from the relationship between the irradiation amount and the reflection density of a solid image on paper or film (FIG. 3). Strictly speaking, one should look at the density of a particular area somewhere in the dot of interest, but cannot be uniquely determined taking edge effects into account.

The mask latent image carrier of the present invention does not include the pattern shown in FIG.

[0038]

As described above, according to the method of the present invention, it is possible to appropriately perform exposure and writing on a mask latent image carrier, and to obtain a high-quality image forming apparatus with no dot displacement. Can be.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a relationship between a high photosensitivity region and the size of a toner image applied to an embodiment of a writing method of an image forming apparatus according to the present invention.

FIG. 2 shows an example of a pattern in which regions having different light sensitivities are arranged on a latent image carrier.

FIG. 3 shows an example of a light beam irradiation pattern.

FIG. 4 shows the relationship between the distribution of islands in the high light irradiation area and the light irradiation area 5;

FIG. 5 is a graph showing a relationship between a light irradiation amount and a reflection density.

[Explanation of symbols]

 Reference Signs List 1 Island in high light sensitivity area 2 Low light sensitivity area 3 Toner image on paper or film 4 Iso-light irradiation energy ray 5 Light irradiation area 6 Minimum irradiation amount that can form toner image 7 Half value of maximum reflection density of toner image Obtained dose

Claims (5)

[Claims] A latent image carrier having periodically arranged islands of a high light sensitivity region in a low light sensitivity region, and transferring and fixing the toner from the latent image carrier onto paper or a film; In a latent image writing method of an image forming apparatus for irradiating a light beam to the latent image carrier of a digital electrophotographic apparatus for forming an image, the area Si of the island in the high photosensitivity area and the corresponding toner image on paper or film When the area St is Si <= S
having a relation of comparison of t. 2. The shape and size of an irradiation range of a light beam to be written only on one high-sensitivity island are superimposed when compared with the shape and size of the high-sensitivity region on the surface of the latent image carrier. And wherein one of the islands in the high light sensitivity region has a shape and size falling within an “irradiation range not less than a minimum irradiation amount capable of forming a toner image on paper or film”. 3. The writing method of the image forming apparatus according to 1., 3. The shape and size of an irradiation range of a light beam to be written only on one high-sensitivity island is determined by comparing the shape and size between the island of the high-sensitivity region and the irradiation light beam on the surface of the latent image carrier. When the two are overlapped, the island of the high photosensitivity area is
2. The writing method of the image forming apparatus according to claim 1, wherein the shape and the size of the toner image fall within an “irradiation range equal to or more than an irradiation amount to obtain a half value of the maximum reflection density of the toner image”. 4. A shape and a size of an irradiation range of a light beam to be written only on one high-sensitivity island are a shape and a size of the high-sensitivity region on the surface of the latent image carrier and a distribution in a low-sensitivity region. When compared with, the islands of three or more high-sensitivity areas aligned on the same straight line do not overlap with the "irradiation range equal to or more than the minimum irradiation amount capable of forming a toner image on paper or film". 4. The writing method for an image forming apparatus according to claim 1, wherein the writing method is a shape and a size. 5. A shape and a size of an irradiation range of a light beam to be written only on one high-sensitivity island are a shape and a size of the high-sensitivity region on the surface of the latent image carrier and a distribution in a low-sensitivity region. When compared with the above, the islands of three or more high-sensitivity areas aligned on the same straight line and the "irradiation range of half or more of the minimum irradiation amount capable of forming a toner image on paper or film" are overlapped. 4. The writing method for an image forming apparatus according to claim 1, wherein the writing method has a shape and a size that do not overlap.