JPH0713773B2 - Image generation method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image forming method using a photoconductor, more specifically, an image in which an image forming process, a transfer process and a cleaning process are continuously and repeatedly performed using the photoconductor. Regarding the generation method.

<Prior Art> As is well known, in an image forming machine such as an electrostatic copying machine, an image forming method using a photoconductor is continuously and repeatedly performed. This image generating method includes an image forming step, a transfer step and a cleaning step. In the image forming process,
The surface of the photoconductor is charged to a specific polarity, and then the photoconductor is exposed corresponding to the image to be formed, thus forming an electrostatic latent image on the surface of the photoconductor. Further, usually, toner is applied to the electrostatic latent image formed on the surface of the photoconductor to develop it into a toner image. In the transfer step, the toner image formed on the surface of the photoconductor is transferred onto a transfer member which may be plain paper (visual image transfer system), or the electrostatic latent image formed on the surface of the photoconductor is developed. Instead, it is transferred onto the transfer member (latent image transfer system). In the latter case, toner is applied to the electrostatic latent image on the transfer member after the transfer step, and this is developed into a toner image. In the cleaning process, the photoconductor is irradiated with static elimination light to eliminate residual charges. Further, in the case of the visible image transfer method, the residual toner on the photoconductor is removed by an appropriate means such as a cleaning blade.

In the image generation method as described above, it is important to consider the following two phenomena, particularly with respect to the irradiation of the static elimination light in the cleaning process. That is, first, the phenomenon relating to the change of the charging characteristic of the surface of the photoconductor must be considered. Generally, when the above-mentioned image forming step, transfer step and cleaning step are performed, so-called traps are generated inside the photosensitive member and electrons or holes are trapped, so-called fatigue is generated in the photosensitive member. Therefore, the charging characteristic of the surface of the photoconductor gradually decreases. The deterioration of the charging property on the surface of the photoconductor lowers the image density in the finally generated image (toner image). Therefore, in order to sufficiently stabilize the image density and generate an image, it is important to sufficiently stabilize the charging characteristics of the surface of the photoreceptor. Second,
A phenomenon relating to the so-called hysteresis characteristic of the photoconductor must be taken into consideration. Generally, the influence of the image formed on the surface of the photoconductor in the previous image generation cycle remains as a so-called history on the photoconductor, and the image formed on the surface of the photoconductor in the next image generation cycle is affected by the previous image formation cycle. In the above, the image formed on the surface of the photoconductor is mixed to some extent, which tends to deteriorate the quality of the image obtained. Therefore, in order to obtain a high quality image, it is important to sufficiently eliminate the above history of the photoconductor in each image forming cycle.

Thus, JP-A-56-155972 discloses that the peak wavelength is relatively long, and therefore the first charge-eliminating light that sufficiently penetrates the photoconductor and acts on the photoconductor to a sufficient depth, and the peak wavelength. However, there is disclosed an image generation method using two types of static elimination light, that is, a second static elimination light that is relatively short, and thus mainly acts only on the surface area of the photoconductor. In this image generation method,
Before actually starting the image generation cycle, the photoconductor is irradiated with only the first charge-eliminating light or the second charge-eliminating light together with the first charge-eliminating light, whereby the photoconductor is brought to a desired state. The tires are actively fatigued, thus avoiding subsequent changes in the charging characteristics of the photoconductor. Then, after the positive fatigue process of the photoconductor, the actual image generation cycle is started. In the cleaning process in this image generation cycle, the second charge removal light is used without using the first charge removal light.
Only the static elimination light of is applied to the photoconductor.

According to the image generating method as described above, which is disclosed in the above-mentioned JP-A-56-155972, the change in image density due to the change in the charging characteristic of the photoconductor surface is avoided, and thus the image density is sufficiently increased. An image can be generated by stabilizing the image. However, (a) it is necessary to perform a positive fatigue step of the photoconductor before actually starting the image generation cycle, and thus a so-called initial waiting time is required.
(B) In the cleaning step in the image forming cycle, only the second charge eliminating light, which has a relatively short peak wavelength and thus mainly acts only on the surface area of the photoconductor, is used. When the photosensitive member is exposed to light corresponding to the image to be formed in the process, traps are likely to be generated inside the photosensitive member and electrons or holes are trapped in the exposed portion of the photosensitive member. Since the static elimination light does not sufficiently pass through the photoconductor, it cannot fully release the electrons or holes trapped inside the photoconductor, and thus only the exposed portion of the photoconductor is locally fatigued and locally charged. There is a problem to be solved that characteristics are deteriorated and so-called history remains.

On the other hand, in Japanese Patent Laid-Open No. 57-212458, in order to solve the above problem (b), both the first static elimination light and the second static elimination light are used in the cleaning step in the image generation cycle. An image generation method of irradiating a photoreceptor is disclosed. In such an image forming method, since the photoconductor is irradiated with the first charge-eliminating light together with the second charge-eliminating light in the cleaning step, the residual charge on the surface of the photoconductor is sufficiently erased and the photoconductor is also removed. The electrons or holes trapped inside are sufficiently released, so that the so-called history of the photoreceptor is sufficiently eliminated.

However, the above-described image generating method disclosed in Japanese Patent Laid-Open No. 57-212458 is not yet sufficiently satisfactory, and the problem (a) remains.
That is, before actually starting the image generation cycle, a so-called initial standby time is set, and during this period, the photosensitive member is irradiated with only the first charge-eliminating light or the second charge-eliminating light together with the first charge-eliminating light. It is necessary to actively fatigue the body to the required state. Otherwise, in the early stage of image generation, the charging characteristic of the photoconductor changes considerably due to the fatigue of the photoconductor.
The image density of the image thus obtained changes considerably.

<Objects of the Invention> The present invention has been made in view of the above facts, and its main purpose is to prevent a change in image density due to a change in charging characteristics of a photoreceptor without requiring a so-called initial standby time. An object of the present invention is to provide an improved image generation method that can avoid the deterioration of the image quality due to the so-called hysteresis characteristic of the photoconductor.

<Summary of the Invention> As a result of earnest research and experiments, the present inventors have surprisingly found that the first peak wavelength is relatively long in the cleaning step as disclosed in JP-A-57-212458.
In the image generation method of irradiating the photoconductor with both the static elimination light and the second static elimination light having a relatively short peak wavelength, the light amount of the first static elimination light is gradually reduced at least at the beginning of image generation. With the improvement, the charging characteristics of the photoconductor can be sufficiently stabilized from the beginning without requiring the so-called initial waiting time, and thus the charging characteristics of the photoconductor can be improved without the so-called initial waiting time. It has been found that it is possible to avoid the change in the image density due to the change and to prevent the deterioration of the image quality due to the so-called hysteresis characteristic of the photoconductor.

That is, according to the present invention, the surface of the photoconductor is charged to a specific polarity, and then the photoconductor is exposed corresponding to the image to be formed,
Thus, an image forming step including forming an electrostatic latent image on the surface of the photoconductor, a transfer step of transferring the image formed on the surface of the photoconductor onto a transfer member, and a peak wavelength passing through the photoconductor. A relatively long first charge-eliminating light and a relatively short second charge-eliminating light whose peak wavelength acts mainly on the surface area of the photoconductor, and a cleaning step including irradiating the photoconductor with the peak. In the image generating method for continuously and repeatedly performing the above; at least at the initial stage of the start of image generation, both the first charge eliminating light and the second charge eliminating light are simultaneously applied to the photoconductor and the first charge eliminating light is irradiated. To gradually reduce the amount of static elimination light,
An image generation method characterized by the above is provided.

<Preferable Specific Examples of the Invention> Hereinafter, more detailed description will be given with reference to the accompanying drawings.

FIG. 1 schematically illustrates the main components of one embodiment of an image generator for performing the improved image generating method according to the present invention. The illustrated image generator includes a rotating drum 2 that is rotatably mounted. The rotating drum 2 has an electrically conductive support base 4 which is grounded, and a photosensitive member 6 provided on the support base 4. The photoconductor 6 is
For example, the selenium-based photosensitive material containing selenium as a main component can be formed of an appropriate known photosensitive material itself. Around the rotary drum 2 which is rotationally driven in the direction shown by the arrow 8, as viewed in the rotational direction, a charging corona discharger 10, a developing device 12, a transfer corona discharger 14, and a peeling corona discharger are sequentially provided. 16, first static elimination lamp 18, second static elimination lamp
20 and a residual toner removing device 22 are provided.

In such an image generator, the image forming step is performed in the image forming area indicated by the symbol A, the transfer step is performed in the transfer area indicated by the symbol B, and the cleaning step is performed in the cleaning area indicated by the symbol C. It In the image forming area A, the surface of the photoconductor 6 is sufficiently uniformly charged to a specific polarity by the action of the charging corona discharger 10.
Next, as shown by an arrow 24, reflected light from the original image or laser light modulated as required is projected on the photoconductor 6 to expose the photoconductor 6 in accordance with the image to be formed. An electrostatic latent image is formed on the body 6. Thereafter, the developing device 12 which may be a well-known magnetic brush type developing device applies toner to the photoconductor 6, and thereby the electrostatic latent image on the photoconductor 6 is developed into a toner image. Transfer area B
, The surface of the transfer member conveyed by an appropriate conveying means (not shown) as indicated by the arrow 26 is brought into close contact with the surface of the photoconductor 6, and the transfer corona discharger 14 transfers the transfer member. The toner image on the photoconductor 6 is transferred to the surface of the transfer member by the action of corona discharge applied to the back surface of the transfer member. The transfer member may be plain paper, for example. Then, the transfer member is peeled from the surface of the photoconductor 6 by the action of corona discharge applied to the back surface of the transfer member from the peeling corona discharger 16. The transfer member having the transferred toner image on its surface is conveyed to an appropriate fixing device (not shown), and the toner image is fixed on the surface of the transfer member in the fixing device, and thereafter it is transferred to the outside of the image generator. Is discharged. In the cleaning area C, the first charge removal lamp 18
Is discharged to the photoconductor 6 and the second charge removal light from the second charge removal lamp 20 is irradiated to the photoconductor 6, and thus the photoconductor 6 is discharged (first and second charge removal light). Irradiation will be referred to later). The residual toner is then removed from the surface of the photoreceptor 6 by the action of the toner removal device 22, which may be of a known form and which has a blade 28 that is pressed against the surface of the photoreceptor 6.

Thus, as disclosed in JP-A-57-212458, the first charge-eliminating light emitted from the first charge-eliminating lamp 18 to the photoconductor 6 has a relatively long peak wavelength. The second charge-removing lamp 20 acts on the photoconductor 6 to sufficiently penetrate the photoconductor 6 to a sufficient depth.
It is important that the second charge-eliminating light having a relatively short peak wavelength is applied mainly to the surface region of the photoconductor 6. The first and second static elimination lights can be appropriately selected according to the photosensitive material forming the photoconductor 6, but particularly when the photoconductor 6 is formed of a selenium-based photomaterial. The first static elimination light is
It has a peak wavelength longer than 600 nm, and the second static elimination light is 600
Advantageously, it has a peak wavelength shorter than nm. And a first static elimination lamp for emitting the first static elimination light
For example, a tungsten lamp is conveniently used as 18, and a second static elimination lamp for emitting the second static elimination light is used.
A green neon lamp is conveniently used as 20, for example. When viewed in the direction of rotation of the rotary drum 2 indicated by the arrow 8, the second static elimination lamp 20 is placed on the upstream side of the first static elimination lamp 18
Can be arranged on the downstream side, but as shown in FIG. 1, the first static elimination lamp 18 is arranged on the upstream side to the second static elimination lamp.
20 is disposed on the downstream side, and the first charge-eliminating light from the first charge-eliminating lamp 18 and the second charge-eliminating light from the second charge-eliminating lamp 20 are at least partially overlapped with each other to form the photoconductor 6 Conveniently, it is illuminated. In the cleaning step, when the first and second static elimination lights are irradiated, the surface of the photoconductor 6 is mainly affected by the action of the second static elimination light, as disclosed in JP-A-57-212458. Residual charges are sufficiently disappeared, and the trapped electrons or holes inside the photoconductor 6 are sufficiently released mainly by the action of the first charge-eliminating light. The residual influence of the image formed in the image generation cycle of 1 is sufficiently eliminated.

However, in the image generating method disclosed in Japanese Patent Laid-Open No. 57-212458, the light amounts of the first and second static elimination lights are not particularly changed. In such a case, from Comparative Example 3 described later, As will be understood, in the initial stage when the rotational driving of the rotary drum 2 is started and the energization of the first and second charge eliminating lamps 18 and 20 is started, the charging characteristic of the photoconductor 6 changes considerably, that is, gradually decreases. Therefore, if the image generation is started immediately, the image density of the obtained image changes considerably in the initial stage. Therefore, in order to obtain an image in which the image density is sufficiently stable, it is necessary to wait for the actual image generation until the charging characteristics of the photoconductor 6 decrease and become stable.

In order to solve such a problem, in the image generating method improved according to the present invention, the rotary driving of the rotary drum 2 is started and the energization of the first and second charge eliminating lamps 18 and 20 is started. It is important to gradually reduce the light amount of the first charge eliminating light at least in the initial stage after the above. By doing so, as will be understood from the examples described later, it is possible to avoid or suppress the change in the charging characteristics of the photoconductor 6 in the initial stage, and thus it is possible to make the charging properties of the photoconductor 6 sufficiently uniform from the initial stage. Therefore, the image generation can be started without setting the so-called initial waiting time, and an image in which the image density is sufficiently stabilized can be obtained.

In order to gradually reduce the light amount of the first charge eliminating light, for example, the voltage applied to the first charge eliminating lamp 18 may be gradually reduced. The initial light amount and the light amount reduction degree of the first charge eliminating light can be appropriately set experimentally according to the characteristics of the photoconductor 6 used.

<Examples and Comparative Examples> Examples Examples were produced by forming As ₂ Se ₃ on an aluminum supporting substrate by vapor deposition of As ₂ Se ₃ to form a photoconductor in an image generator as shown in FIG. 1. A rotating drum (photoconductor thickness 60 μm, photoconductor outer diameter 90 mm) was continuously rotatably driven at a peripheral speed of 159 mm / sec. Then, while the rotary drum was continuously rotated, the energization of the charging corona discharger was started, and at the same time, the energization of the first discharge lamp and the second discharge lamp was started. A DC voltage of +5.5 KV was applied to the charging corona discharger. As the first static elimination lamp, a tungsten lamp sold by Toshiba Corporation under the product number "A7473 No.86" is used, and a DC voltage of + 19V is applied at the time of energization. As shown in the figure, the change was made, that is, it was gradually reduced to + 10V from the time of energization to about 1 minute and 30 seconds, and thereafter kept at + 10V. As the second static elimination lamp, the product number “RF6-G” from Okaya Electric Industry Co., Ltd.
Using a green neon lamp sold as "B9", the DC voltage of AC100V was continuously applied without changing from the time of energization.

Then, in order to avoid the influence of the so-called start-up (start of energization), which is unique in the charging corona discharger, the first static elimination lamp, and the second static elimination lamp, the charging corona discharger, The surface potential of the photoconductor was continuously measured at the developing position from the time when one second had elapsed from the time when the first static elimination lamp and the second static elimination lamp were energized. For measuring the surface potential, a surface potential measuring instrument sold under the product number “360 SXJX” by Trek Corp. of the United States was used. The measurement results are shown in FIG. 3, and were substantially constant from the start of measurement.

Comparative Example 1 The surface of the photoconductor was the same as that of the example except that the second static elimination lamp was not energized at all and the DC voltage of +20 V was applied without changing the first static elimination lamp. The potential was measured continuously. The results are as shown in FIG. 3, and the surface potential continued to decrease significantly at the beginning of the measurement.

Comparative Example 2 The surface potential of the photoconductor was continuously measured in the same manner as in Example except that the first charge eliminating lamp was not energized at all. The result is as shown in FIG. 3, and although the surface potential was slightly lowered at the very beginning of the measurement, it was substantially constant thereafter.

Comparative Example 3 The surface potential of the photoconductor was continuously measured in the same manner as in Example except that the DC voltage of +10 V was continuously applied from the time of energizing the first static elimination lamp. The results are shown in FIG. 3, and the surface potential continued to drop considerably at the beginning of the measurement.

[Brief description of drawings]

FIG. 1 is a simplified cross-sectional view illustrating the main components in one embodiment of an image generator for performing the improved image generating method according to the present invention. FIG. 2 is a diagram showing a change in the applied voltage of the first charge eliminating lamp in the embodiment. FIG. 3 is a diagram showing the measurement results of surface potentials in Examples and Comparative Examples 1 to 3. 2 ... Rotating drum 4 ... Conductive support base 6 ... Photoconductor 10 ... Charging corona discharger 12 ... Developing device 14 ... Transfer corona discharger 16 ... Peeling corona discharger 18 ... No. 1 static elimination lamp 20 …… second static elimination lamp 22 …… Residual toner removal device

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-56-155972 (JP, A) JP-A-57-212458 (JP, A) JP-A-55-101959 (JP, A) JP-A-56- 24383 (JP, A) JP 60-14255 (JP, A) JP 57-14859 (JP, A) JP 53-148444 (JP, A) JP 55-98777 (JP, A)

Claims (5)

[Claims] 1. An image forming process comprising charging a surface of a photoconductor to a specific polarity and then exposing the photoconductor to an image to be formed, thereby forming an electrostatic latent image on the surface of the photoconductor. And a transfer step of transferring an image formed on the surface of the photoconductor onto a transfer member, and a relatively long first charge-eliminating light having a peak wavelength sufficient to pass through the photoconductor and the photoconductor having the peak wavelength. A cleaning step including irradiating the photoconductor with both a relatively short second charge-eliminating light that acts on the surface area of the image forming apparatus, and an image forming method in which the cleaning step is continuously repeated; , Simultaneously irradiating the photosensitive member with both the first static elimination light and the second static elimination light, and gradually reducing the light amount of the first static elimination light,
An image generation method characterized by the above. 2. The image generating method according to claim 1, wherein the first charge eliminating light has a peak wavelength longer than 600 nm, and the second charge eliminating light has a peak wavelength shorter than 600 nm. . 3. The image generating method according to claim 2, wherein the first static elimination light is a tungsten lamp light. 4. The image generating method according to claim 2 or 3, wherein the second charge eliminating light is green neon lamp light. 5. The image forming method according to claim 2, wherein the photoconductor is a selenium-based photoconductor.