JPS6249364A - Forming method for electrostatic latent image - Google Patents

Abstract

PURPOSE:To simplify a developing process and to improve optical sensitivity by impressing a DC voltage with reverse polarity against applied electric charge to a part between both conductive layers, and simultaneously exposing an optical image to form a charge image corresponding to the optical image on a dielectric layer. CONSTITUTION:A charge receptor 6 consisting of a conductive layer 4 and a dielectric layer 5 is tightly adhered to an electrode body 3 consisting of a conductive layer 1 and a dielectric layer 2 so that respective dielectric layer sides are brought into contacted with each other and a DC voltage is impressed between respective conductive layers 4, 1 by a power supply 7, so that about -240V surface charge is uniformly applied to the surface of the dielectric l ayer 5 of the charge receptor 6. A photosensitive body 11 consisting of a base layer 8, a conductive layer 9 and a photosensitive layer 10 is tightly adhered to the charge receptor 6 by a guide roller 22 so that the photosensitive layer 10 is contacted with the dielectric layer 5, about 550V DC voltage inverting the polarity of the conductive laye 4 of the receptor 6 is applied between respective conductive layers 4, 9 by a power supply 12, and simultaneously with the impression of the DC voltage, an original image is exposed by an optical system. Consequently, an electrostatic latent image can be formed on the dielectric layer of the charge receptor 6 and the optical sensitivity can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an electrostatic latent image forming method applied to copying machines and the like.

Prior Art Conventionally, as a method for forming an electrostatic latent image, US Pat.
, 057,720.

A photoreceptor consisting mainly of a base layer, a conductive layer, and a photosensitive layer is brought into close contact with a charge receptor consisting of a dielectric layer and a conductive layer to expose a light image, and at the same time, a DC voltage is applied between each conductive layer to generate a charge. Some are designed to form an electrostatic latent image on the dielectric layer of the receptor.

In the electrostatic latent image formed on the charge receptor by such a method, the light irradiated portion is a region where a charge exists, and the non-irradiated portion is a region where no charge is present. In other words, the electrostatic latent image becomes a negative image with respect to the exposed image. Even if such an electrostatic latent image is formed as a negative image, reversal development may be performed to make it into a positive image. However, depending on the characteristics of the charge receptor, the charges existing on the dielectric layer of the charge receptor and the corresponding charges of opposite polarity, which are thought to exist mainly on the conductive layer of the charge receptor, may exist very close to each other. The surface of electrostatic recording paper, which is commonly used as a charge receptor, is rough and is affected by a microscopic strong electric field on the dielectric layer called a microfield. In many cases, it is difficult to make the image positive.

Purpose The present invention was made in view of the above points, and it is possible to form an electrostatic latent image as a positive image with respect to an exposed image.
It is an object of the present invention to provide an electrostatic latent image forming method that can simplify the development process and improve the photosensitivity during exposure.

Structure In order to achieve the above-mentioned object, the present invention imparts a uniform charge on the dielectric layer of a charge receptor consisting of a conductive layer and a dielectric layer, and applies a uniform charge to the dielectric layer of a photoreceptor mainly consisting of a base layer, a conductive layer and a photosensitive layer. The dielectric layer is opposed to the photosensitive layer, the charge receptor is brought into close contact with the photosensitive layer, and a DC voltage having a polarity opposite to the applied charge is applied between both conductive layers, and at the same time, a light image is generated from one side of the photoreceptor or the charge receptor. It is characterized in that it is exposed to light to form a charge image corresponding to the light image on the dielectric layer of the charge receptor.

An embodiment of the present invention will be described below based on the drawings. First, the basic system of the present invention will be explained with reference to FIG. Same figure (
As shown in a), an electrode body 3 consisting of a conductive layer 1 and a dielectric layer 2, and a charge receptor 6 such as electrostatic recording paper consisting of a conductive layer 4 and a dielectric layer 5 are connected to each dielectric layer 2, 5 are placed in close contact with each other so as to face each other, and a DC voltage E1 is applied by a power source 7 between each conductive layer 1.4. Then, after a certain period of time has elapsed, the electrode body 3 and the charge receptor 6 are peeled off while the voltage is being applied or after the voltage is turned off. Charge receptor 6 after peeling
is shown in the same figure (b). As shown in this figure, uniform charges exist on the dielectric layer 5 of the charge receptor 6.

After applying a uniform charge to the dielectric layer S of the charge receptor 6 in this manner, as shown in FIG. 11
A charge receptor 6 is brought into close contact with the photosensitive layer 1o so that the dielectric layer 5 faces the photosensitive layer 1o. In this state, the same figure (a)
A DC voltage E2 is applied between the conductive layers 4 and 9 by a power source 12 whose polarity on the charge receptor 6 side is opposite to that shown in FIG. With the voltage applied in this way, the same figure (d
), the light image is exposed. For this reason, both the photoreceptor 11 and the charge receptor 6 are translucent, but in this embodiment, the photoreceptor 11 is made translucent and exposure is performed from the side of the photoreceptor 11. . At this time, the same figure (d
), the left side is the light irradiated part and the right side is the non-irradiated part. Now, in the light irradiated part on the left side, the conductivity of the photosensitive layer 10 increases due to the light, so the air layer between the photoreceptor 11- and the charge receptor 6 causes dielectric breakdown, and the charge receptor 6 The charge moves toward the dielectric layer 5 of the charge acceptor 6, and
Decrease the amount of charge on top. Due to this.

The charges on the dielectric layer S of the charge receptor 6 will be reduced, neutralized, or given some charges of opposite polarity (the figure (d) shows a neutralized state). . On the other hand, the non-irradiated part on the right side does not receive light, so the photoreceptor 1
The photosensitive layer M10 of No. 1 remains an insulator, no charge transfer occurs, and the charges on the dielectric layer 5 of the charge receptor 6 remain as they are. After short-time exposure and voltage application in this manner, the charge receptor 6 is peeled off from the photoreceptor 11. The charge receptor 6 after peeling is shown in the same figure (e).

In this way, the electrostatic latent image formed on the dielectric layer 5 of the charge receptor 6 has charge present in the non-light irradiated area, and a small amount of charge or no charge in the light irradiation area. Alternatively, a state exists in which a charge having a polarity opposite to that of the non-irradiated portion exists. In other words, the electrostatic latent image is a positive latent image compared to the exposed image when viewed from the polarity of the charge in the non-irradiated area. Therefore, there is no need for reversal development, and a positive image can be easily obtained using toner having a polarity opposite to that of the non-irradiated portion of the charge receptor 6 on the dielectric layer 5.

Here, in FIGS. 1(a) and 1(b) described above, it is important to have the dielectric layer 2 in the electrode body 3 in order to apply a uniform charge to the dielectric layer 5 of the charge receptor 6. It becomes a point. The reason for this will be explained below. First, in FIG. 1(a), the electrostatic transfer of the charge receptor 6 onto the dielectric layer 5 is carried out in the dielectric layer 2 of the electrode body 3 and between the charge receptor 6 and the electrode body 3.
This occurs due to the movement of charges in the air space between the two. This charge transfer mechanism is explained using the Paschen curve shown in FIG. 2 based on the discharge phenomenon. This Paschen curve is
This shows the relationship between the dielectric breakdown voltage V and the dielectric film thickness dr (μ). If the layer spacing is d and the relative dielectric constant is εr, then the dielectric film thickness d
r is expressed as dr=d/sr.

Now, in FIG. 1(a), the conductive layer 1 does not have the dielectric layer 2.
Consider the case where an electrode body 3 made of In this case, the space between the conductive layers 1 and 4 is formed only by the air layer and the dielectric layer 5. Here, the dielectric layer 5 of the charge receptor 6 made of electrostatic recording paper or the like is generally formed on a base paper to a thickness of about 7 μm by dispersing pigments and other substances in plastic. For example, the surface should be
It is formed into an uneven shape of about 10 μm. Therefore, there is a so-called weak point where the dielectric layer 5 can be ignored locally. Considering such a weak point portion, the dielectric film thickness dr is given only by the air layer, and since the relative permittivity of air is εr=1, dr=d. Therefore, looking at the Paschen curve shown in Figure 2, when the dielectric film thickness dr is greater than 7μ, the breakdown voltage becomes a linear function of the dielectric film thickness, but below 7μ, the breakdown voltage becomes sharply upward. . In actual cases, it is very difficult to keep the thickness of the air layer uniform, and in places where the air layer spacing is very small, 7μ or less, the voltage applied to the air gap when applying DC voltage is The dielectric breakdown voltage for this air gap will not be exceeded and dielectric breakdown of the air will not occur, but in places where the air gap takes a value of 7μ or more, the voltage applied to the air gap will exceed the dielectric breakdown voltage and the air will not break down. dielectric breakdown occurs and charge transfer occurs. In other words, in electrostatic transfer from the electrode body 3 to the charge receptor 6, there are parts where the charge is transferred and parts where it is not transferred, so it is difficult to apply a uniform charge to the dielectric layer 5 of the charge receptor 6. It is something that cannot be done.

However, this problem can be solved by using the electrode body 3 having the dielectric layer 2 together with the conductive layer 1 as in this embodiment. The dielectric film thickness dr in this case is the dielectric film thickness d of the dielectric layer 2.
It is given by the sum of r1 and the dielectric film thickness dr2 of the air layer.

Therefore, the dielectric film thickness dr1 of the dielectric layer 2 is adjusted so that the dielectric film thickness dr (=d r By giving , the dielectric breakdown voltage takes a region given by a linear function of the dielectric film thickness dr in the Paschen curve shown in FIG. Therefore, charge transfer occurs uniformly, and charges are uniformly applied to the dielectric layer 5 of the charge receptor 6.

Now, let's consider the conditions during exposure.

Conventionally, a charge is applied to the dielectric layer of the charge receptor by applying a DC voltage during exposure. In this regard, in this embodiment, it is applied on the dielectric layer 5 of the charge receptor 6 before exposure.
The DC voltage applied during exposure is applied to the dielectric layer 5 of the charge receptor 6.
This is to reduce or neutralize the surface charge or to add a slight surface charge. Therefore, according to the method of this embodiment,
Both the exposure amount and the applied voltage are lower compared to conventional methods,
The photosensitivity of the photoreceptor 11 is improved. For example, when trying to obtain an electrostatic latent image using the conventional method, the exposure amount:
9.0xlO-'J/al? , applied voltage: 700 V was required, but as in this example, before exposure (Fig. 1 (
In a)), if the applied voltage E = -1050V, during exposure, exposure i: 6.0XIO-"J/ci,
An electrostatic latent image was obtained at an applied voltage E of 550V.

In addition, when applying the voltage shown in FIG. 1 (, +), by making the dielectric film thickness dr of the dielectric layer 2 of the electrode body 3 into a halftone state, the magnitude of the dielectric film thickness dr can be determined from the Paschen curve shown in FIG. It can be seen that a difference appears in the dielectric breakdown voltage. Therefore, in the electrostatic transfer process shown in FIG. 1(a), charge transfer occurs in a dot-like manner, and charges are applied to the dielectric layer 5 of the charge receptor 6 in a dot-like manner. As a result, Fig. 1(b)
In the steps shown in (d) to (d), the halftone effect improves the reproducibility of the intermediate density portion of the image. Figure 3 shows one surface of the conductive layer 1 of the electrode body 3 at a pitch of 20 to 1000μ.
The thickness d of the dielectric layer 2 is distributed in the form of dots by using a conductive material or conductive cloth in the form of dots, and the dielectric film thickness dr thereof is made into a dot state. In addition, in the experiment of forming an electrostatic latent image in this example, a conductive cloth (trade name: Seiren M "Electronic") was used, in which a polyester fabric was subjected to conductive treatment with nickel and the surface was coated with a urethane film (40μ thick). Fiber Plat 5i-11J) is used.Furthermore, Fig. 4 shows that the dielectric layer 2 is made of
Dielectric layer 2a made of different materials with r.

2b is distributed in the form of halftone dots at a pitch of 20 to 1000 .mu.m, and a film thickness of 1 dr is taken as a halftone dot state.

In addition, in FIGS. 1(Q) and (d), the polarity of the DC voltage applied between the photoreceptor 11 and the conductive layers 9 and 4 of the charge receptor 3 is such that the photoreceptor 11 side is positive. However, depending on the photosensitive layer 10 of the photoreceptor 11, the DC voltage may be applied so that the side of the photoreceptor 11 is negative. In this case, the polarities of the applied voltages and the signs of + and - shown in FIGS. 1(a) to (e) may all be reversed.

Next, a configuration example of a copying apparatus using the present invention will be described with reference to FIGS. 5 to 7.

First, a document table 15 on which a document 14 is set and moves is provided at the top of the copying machine main body 13.

A lamp 17 that exposes the original 14 through the slit 16, a first mirror 19, an in-mirror lens 20, and a second mirror 21 that form an image of reflected light from the original 14 on the electrode drum 18 are provided. . As described above, a transparent sheet-like photoreceptor 11 consisting of a base layer, a conductive layer, and a photosensitive layer is attached to the electrode driver 1118 at the image-forming portion of the document image via the guide roller 22 and the take-up roller 2.
3 so that it can be wound freely. On the other hand, with respect to such an electrode drum 18, a charge receptor 6, specifically an electrostatic recording paper, is placed on the paper force receptors 1 to 2 with the dielectric layer 5 side facing up.
4 and is fed by a paper feed roller 25. At this time, in order to prevent electrostatic unevenness from occurring on the dielectric layer 5 of the charge receptor 6, the surface of the paper feed roller 25 is made of a conductive material 1, such as metal, conductive rubber, etc. It is grounded through the resistor.

The charge receptor 6 fed by the feed roller 25 in this manner is fed by the registration roller 26 toward the electrode driver 1118 in time with exposure, which will be described later.

This charge receptor 6 is in close contact between the electrode drum 18 and the roller-shaped electrode body 3. The details at this time are shown in FIG. 6. The charge receptor 6 consisting of a conductive layer 4 and a dielectric layer 5, and the electrode body 3 consisting of a conductive layer 1 and a dielectric layer 2 have their respective dielectric layers 5.2 side The conductive layers 4 and 1 are brought into close contact with each other, and a DC voltage of about -10 oOv is applied between the conductive layers 4 and 1 by an electric current g7. As a result, a surface charge of about -240 V is uniformly applied to the dielectric layer 5 of the charge receptor 6. At this time, the conductive layer 4 side of the charge receptor 6 is connected to the electrode drum 1.
Grounded by 8.

Note that a charge receptor 6 is provided between the electrode body 3 and the electrode drum 18.
It is best to turn off the DC voltage when there is no However, since the dielectric layer 2 of the electrode body 3 acts as a protective layer, the DC voltage may remain applied.

The charge receptor 6 to which a uniform surface charge has been applied in this manner is brought into close contact between the photoreceptor 11 and the electrode drum 18 by the guide roller 22 .

Details at this time are shown in FIG. A photoreceptor 11 consisting of a base layer 8, a conductive layer 9, and a photosensitive layer 10 and a charge receptor 6 are brought into close contact with each other by a guide roller 22 so that the photosensitive layer 10 and the dielectric layer 5 are in contact with each other, and between each conductive layer 4, 9. Then, a DC voltage of about 550 V is applied by the power source 12 so that the conductive layer 4 of the charge receptor 6 has the opposite polarity. At the same time as this DC voltage is applied, the original image is exposed by the optical system. 27.2
8 is a light shielding plate. This optical image is formed in a portion where the photoreceptor 11 and the charge receptor 6 are in close contact with each other. Now, when the exposure light amount is set to 0.5X10-' to 0.6X10-'J/d, the amount of 1200 to +5
An electrostatic latent image of approximately 0 V was obtained. Incidentally, at the timing when the charge receptor 6 is not present between the photoreceptor 11 and the electrode drum 18, it is preferable to turn off the DC voltage in order to prevent fatigue of the photoreceptor 11.

In this way, a positive latent image is formed on the dielectric layer 5 of the charge receptor 6 with respect to the original 14 by the application of a DC voltage before exposure, the optical image exposure, and the application of a DC voltage during this exposure. Such a charge receptor 6 is a mylar 30 attached to a guide plate 29.
It is peeled off from the electrode driver l''=18 and transferred to the developing section 31.
The image is then sent to be developed. The developing section 31 is shown to be of a low-resistance-component developing type, but any developing type may be used. In addition, a dry two-component developing type, a wet type developing type, etc. may be used. Here, when using the developing section 31 of a low-resistance component development method as shown in FIG. The shape of the back electrode roller 31a may be formed, for example, as shown in FIG. ), paper ejection roller 33
As a result, the paper is ejected onto the paper ejection tray 34.

Incidentally, as shown in FIG. 9, an electrode belt 35 may be used instead of the electrode drum 18.

Further, as the electrode body 3, a roller 3 is used as shown in FIG.
A belt-like member supported by 6 may also be used. Furthermore, a uniform charge distribution may be applied to the dielectric layer 5 of the charge receptor 6 using a charger without using the electrode body 3. In addition, the exposure optical system is not limited to the combination of mirror and in-mirror lenses.
It may also be a roof mirror lens array or a combination of a rinse and a mirror.

Effects In the present invention, as described above, a uniform charge distribution is imparted to the dielectric layer of the charge receptor before exposure, and then, during photoimage exposure, a DC voltage with a polarity opposite to that before exposure is applied. As a result, an electrostatic latent image that becomes a positive image with respect to the exposed image can be formed on the dielectric layer of the charge receptor, and therefore a positive developed image can be obtained by a normal development method. ,
Further, regarding conditions during exposure, the amount of exposure and applied voltage can be reduced, and an electrostatic latent image can be formed with improved photosensitivity.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIGS.
(e) is a principle diagram showing the process order, FIG. 2 is a characteristic diagram of the Paschen curve, FIGS. 3 and 4 are cross-sectional views showing a modification with a halftone structure, and FIG. 5 is an example of application to a copying machine. FIG. 6 is a side view showing an enlarged part of it, FIG. 7 is a side view showing a different part enlarged, and FIG. 8 shows the shape of the back roller of the developing section. The front view, FIG. 9, and FIG. 10 are schematic side views showing different modifications. DESCRIPTION OF SYMBOLS 1... Conductive layer, 2... Dielectric layer, 3... Electrode body, 4
...Conductive layer, 5-1. dielectric layer, 6... charge acceptor,
ε...Base layer, 9...Conductive layer, 1o...Photosensitive layer, 11...Photosensitive suspension Application Person Li Co., Ltd.
Co-3.1 Figure 32, Figure 33 - The horse is a figure, y37 figure, %+5 figure

Claims (1)

[Claims] 1. Applying a uniform charge on the dielectric layer of a charge receptor consisting of a conductive layer and a dielectric layer, and applying a uniform charge to the photosensitive layer of a photoconductor consisting mainly of a base layer, a conductive layer and a photosensitive layer. The dielectric layers are placed opposite each other, the charge receptor is brought into close contact with the charge receptor, and a DC voltage having a polarity opposite to that of the applied charge is applied between both conductive layers. 1. A method for forming an electrostatic latent image, which comprises forming a charge image corresponding to a light image on a dielectric layer of a charge receptor. 2. In applying a charge to the dielectric layer of the charge receptor, an electrode body consisting of a conductive layer and a dielectric layer is brought into close contact with the charge receptor with each dielectric layer facing each other, and a DC voltage is applied between each conductive layer. The electrostatic latent image forming method according to claim 1, characterized in that: is applied. 3. The electrostatic latent image forming method according to claim 2, wherein the dielectric layer uses an electrode body having a halftone dot structure.