JPS5999457A - Image forming method - Google Patents

Abstract

PURPOSE:To complete development in one process by electrically charging an imge carrier where a bipolar photoconductive layer an insulating layer are laminated, performing image carrier after destaticization, and exposing a part corresponding to an image and forming a bipolar electrophotographic image. CONSTITUTION:The image carrier 1 is formed by laminating the bipolar photoconductive layer 1B and insulating layer 1C on a conductive substrate 1A. The carrier 1 is charged negatively by using an electric charger 3 to a -1,300V surface potential. Then, destaticization is carried out by a discharger 2 to a 400V surface potential and then image exposure is performed to form an image so that the surface potentials of a dark part D and a light part L are 400 and -100V respectively. Then, positive charging is carried out by using the charger 3 to a +1,600V surface potential. Destaticization is performed by the discharger 2 to a -100V surface potential. Then, a corresponding image is written and the surface potentials of an irradiated part I and an unirradiated part NI are set to 400 and -100V respectively. Consequently, the development is completed in one process.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention forms an electrophotographic image corresponding to, for example, an image of a document, and an electrophotographic image written based on an image signal and corresponding to an N71C original image. The present invention relates to an image forming method including steps.

[Technical background of the invention and its problems]

This type of image forming method is applied, for example, when an analog image (based on the original image) using a lens system and a digital image (based on the image signal) using a laser, LED, etc. are formed using the same device. It is an indispensable technology for creating multifunctional image forming apparatuses by adding printer functions or editing functions to copying machines.

However, whereas the curling process conventionally applied to copying machines forms a positive latent image, the process uses a laser or LED to write a light image based on an image signal to form a latent image. forms a negative latent image. Therefore, when forming an image by superimposing both processes, separate developing processes are required, and there are various problems in realizing this. In addition, in order to solve this problem, in the process of writing an optical image based on an image signal to form an a-image, a positive latent image is formed by irradiating the source corresponding to the part where there is no image signal. However, in such a process, the writing process of the optical image becomes complicated, and if it is not performed at high precision, it becomes impossible to completely erase the potential of the irradiated part of the source. This results in a new problem of fogging.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and it is possible to form an electrophotographic image with the same polarity in the original non-irradiated area and the original irradiated area corresponding to the image during image exposure, and as a result, it is possible to form an electrophotographic image with the same polarity. It is an object of the present invention to provide an image forming method that can visualize an electrophotographic image using a single developing means, and that can contribute to increasing the functionality of an image forming apparatus.

[Summary of the invention]

In order to achieve the above object, the present invention charges an image carrier formed by laminating a bipolar photoconductive column layer and an insulating layer to a first polarity with respect to a reference potential, and then charges the image carrier to a first polarity. By setting the polarity to 2 and further performing image exposure, the second
a first electrophotographic image forming step of forming an electrophotographic image with a polarity of , charging the image carrier with a second polarity with respect to a reference potential, and then discharging the image carrier to near the reference potential;
The image forming apparatus further includes a second electrophotographic image forming step of irradiating the image carrier with a source corresponding to the image to form an electrophotographic image with a second polarity on the irradiated portion of the source. be.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view showing the structure of an image carrier. The image carrier 1 is formed by laminating a conductive substrate IA made of aluminum or the like, a bipolar photoconductive column layer 1B, and an insulating layer 1C. The photoconductive column layer 1B is, for example, Set
Se T e s A '2 St 3 * ZnOe
Inorganic photoconductive materials such as a-5t eCdS and PVK.

It can be formed from an organic photoconductive material such as PVK-TNF. The insulating layer 1C is
In short, it is made of an insulating material that can transmit a part of the spectral wavelength of the photoconductive column layer 1B.
Bye. As a method of laminating such an image carrier, for example, a photoconductive columnar layer 1B made of α-5i with a thickness of 15 μm is formed on a conductive substrate 1A.

There is a method of overlapping Mylar with sufficient tension and adhering a part of it to form an insulating layer ICvf-. In the image carrier 1 having such a two-layer structure, an electrophotographic image, such as a latent image, is formed by contrast due to a difference in surface potential. As shown in FIG.
When the capacitance of the photoconductive layer 1B is 0 at z (F/li)
1 (F/ba), the surface charge is C2 (
C1tyi), and the charge on the bottom surface of the insulating layer 1C is Ql(C1tyi).
/ba), then Fi, (in this case, the conductive substrate 1
1 becomes -QIQ2) Generally, V shown in the first equation
J? becomes.

Next, the image carrier 1 is charged to a first polarity with respect to a reference potential, and then the image carrier is charged to a second polarity,
A first electrophotographic image forming step of forming an electrophotographic image with a second polarity by further imagewise exposure will be described. Figure 6 ('') s ('') t (C)? -! FIG. 3(d) is an explanatory diagram of the movement of charges in the first electrophotographic image forming step, and is an explanatory BA diagram of the change in surface potential in the first electrophotographic image forming step.

First, the image carrier 1 is charged with a first polarity relative to a reference potential. For example, in a bright place of 500 to 1000 Ltb2-, negative charging is performed using a charger 3 that flows a current of -1.0 (μV) with respect to zero potential. As a result, Figure 3 (α)
As shown in , negative charges remain on the surface of the insulating layer 1C, and since it is photopic charged, the resistance of the photoconductive layer 1B is reduced, and as a result, the same amount of positive charges as the negative charges are transferred to the bottom surface of the insulating layer 1C. , and the surface potential of the image carrier 1 is 11,300 VC (Fig. 6 @)
Vl at ). Note that this step is not limited to charging in a bright place, but it is also possible to expose the image bearing member in advance and perform charging while the photoconductive i-layer has sustained conductivity. In particular, since charging and exposure do not need to be performed simultaneously in this way, strict timing matching is not required when executing this process.

Then, this image carrier is neutralized to have a second polarity. For example, a static eliminator 2 that flows a current of 0.6 (μβ) with respect to zero potential
Remove static electricity. As a result, as shown in FIG. 3(h), the negative charge on the surface of the insulating layer 10 is reduced by the positive charge due to static electricity removal, and the surface potential of the image carrier 1 becomes 400V (Vz in FIG. 3(d)). become.

Next, the image carrier 1 is subjected to image exposure using reflected light from the original.

Then, as shown in FIG. Since the resistivity of the photoconductive layer 1B is lowered in L (which corresponds to the background color part of the original), the lower surface of the insulating layer 1c is coated with the same amount as the upper surface of the insulating layer 1C. A polar positive charge remains.As a result, the dark area D6
r) The surface potential is 40 D V (i Figure 3 (d) (D
V3)-1', the surface potential of the light part is 1100V (
V4) in FIG. 6), and an electrophotographic image is formed due to the contrast due to the difference in surface potential between the two.

Next, the image carrier 1 is charged with a second polarity with respect to the reference potential, and then the image carrier is neutralized to near the reference potential, and further, by irradiating the image carrier with a source corresponding to an image, An electrophotographic image is formed on this original irradiated portion with a second polarity. The second electrophotographic image forming step will be explained. Figure 4 (α).

(C) t′i An explanatory diagram of the movement of charges in the second electrophotographic image forming process, FIG. .

First, the image carrier 1 is charged with a second polarity relative to the reference potential. For example, in a bright place of 500 to 1000 L1t, g, positive charging is performed using a charger 6 that flows a current of +1.6 (μq/1yyf) with respect to zero potential. As a result, the fourth
As shown in Figure (α), positive charges remain on the surface of the insulating layer 1c, and since the EA is also charged, the resistance of the photoconductive layer 1B is reduced, and as a result, the same amount of negative charges as the positive charges are insulated. It gathers on the lower surface of layer 1C, and the surface potential of image carrier 1 increases to +1600VC.
Vt) in Figure 4Cd). Note that this process is not limited to charging in a bright place; the entire surface of the image carrier is charged in advance! It is also possible to trap charging while there is sustained conductivity at f and 'L. In particular, in this way, charging and =yt do not need to be performed at the same time, so strict timing matching is not required when executing this process.

Then, the charge on the image carrier is removed to near the reference potential. For example, with respect to zero potential, the static eliminator 2 which flows a current of -0.9 (μqAyhυ) performs negative charging and eliminates the static charge. As a result, as shown in FIG. 4Cb, the positive charge on the surface of the insulating layer 10 is The surface potential of the image carrier 1 decreases by 1100 cm (V2 in FIG. 4(d)).
)become.

Next, the image carrier 1 is irradiated with light corresponding to one image.
For example, a laser source writes an optical image based on an image signal. Then, as shown in FIG. 4(C), there is no inflow of charge in the unirradiated area Nl of the laser source, and in the irradiated area I, the resistance of the photoconductive columnar layer 1B becomes low, so that the lower surface of the insulating layer 1C The same amount of negative charges with the opposite polarity as on the upper surface of the insulating layer 1C remains on the upper surface of the insulating layer 1C.

As a result, the surface potential of the irradiated part I was 400V (Fig. 4(d)
), and the surface potential of the unirradiated area Nl becomes V4) at 11 oov (41st/@), and an electrophotographic image is formed by the contrast due to the difference in surface potential between the two.

Here, the static eliminator used in the first and second electrophotographic image forming steps will be explained. It is desirable that the static eliminator is effective in keeping the surface potential of the image carrier constant. This is because, as is clear from the above explanation (see FIGS. 3(d) and 4(d)), a constant surface potential must be formed after static electricity removal.

FIG. 5 is a schematic explanatory diagram showing the configuration of the static eliminator.

This static eliminator 2 connects a charge wire 1 with an AC voltage power source 11 of 4.2 KV through a capacitor 10 of 0.0 iμF.
2, and a DC voltage power source 14 is applied to the shield 16.
ing.

Note that the structure of the static eliminator can be as shown in FIG. 6 or 7 in addition to the above-described structure, and in short, any structure can be used as long as it has the ability to reduce the surface potential of the image carrier. It is also possible to In the case shown in FIG. 6, a high-voltage DC power source 20 is applied to a charge wire 21, and the polarity of the applied voltage is a negative potential when removing a positive charge.

When removing negative charges, the potential is positive, and the shield case 22 is grounded, so that the stable point of the surface potential can be freely changed depending on the voltage value applied to the grid 24 by the low-voltage DC power supply 23. It is configured as follows. 7th
In the case shown in the figure, the shield case 30 is grounded and activated.
A high voltage is applied to the charge wire 61 by an AC power source 32 and a DC power source 33, and the structure is such that the stable point of the surface potential can be freely changed depending on the voltage and polarity of the DC power source. I'm here.

Next, an example of an image forming apparatus equipped with Ml and a second electrophotographic image forming step will be described with reference to FIG. 8. This device includes a drum-shaped image carrier 1 rotatably installed approximately in the center of the main body, and a charger for photopic charging (equipped with a tungsten lamp for exposure and a charge wire for charging).
6, the static eliminator 2 shown in FIG.
an image exposure unit 44 that irradiates a source from a lamp 46 to a document that is being placed and performs image exposure using the reflected light; and an optical image writing unit 4 that irradiates a laser source and writes an optical image based on an image signal.
5, a full-surface exposure rung 46 for performing full-surface exposure, a developing means for developing the electrophotographic image formed on the image carrier 1, for example, an fA image container 47 for developing the electrophotographic image with a developer, and a paper. A paper feed section 48 supplies sheets one by one toward the curved portion of the image carrier 1, and a developer (a developer 47) on the image carrier 1 is applied to the paper fed by the paper feed section 48. A transfer charger 49 that transfers the developer (attached to the photographic image), a peeling section 50 that peels the developed paper from the image carrier 1, and a fixing unit that fixes the developer on the peeled paper to the paper. 51, a paper tray 52 from which the fixed paper is ejected, a cleaning section 56 that cleans the developer remaining on the image carrier 1 after transfer, and a main motor 54. There are n.

The first electrophotographic image forming unit '8 in such an apparatus photopic charges the image carrier 1 with the charger 3, then removes the charge with the charge eliminator 2, and further removes the charge from the original with the image exposure section 44. The image carrier 1 is imagewise exposed to the reflected light and then removed.

Through this process, as explained in FIG.
V4) in FIG. 6@), and an electrophotographic image is formed due to the contrast due to the difference in surface potential between the two. Also.

The second electrophotographic image forming step in such an apparatus is
The image carrier 1 is photopic charged by the charger 6, then the charge is removed by the charge eliminator 2, and an optical image is written by the optical image writing section 45 by irradiating a laser source based on an image signal. Ru. Through this process, the surface potential of the irradiated part I is increased to 400V (Fig. 4(d)
), the surface potential of the unirradiated area Nl is 11
00V (V4 in FIG. 4(d)), and an electrophotographic image is formed due to the contrast due to the difference in surface potential between the two.

In this apparatus, when performing the second electrophotographic image forming step after the first electrophotographic image forming step, first, after forming the electrophotographic image in the first electrophotographic image forming step, This electrophotographic image is developed in the developing device 47. Thereafter, the image carrier 1 rotates in the direction of the eighth internal clock counterclockwise hand, but at this time, the paper feed section 48. The transfer charger 49 and cleaning section 53 are not operated. Then, the second electrophotographic image forming process is repeated on the image carrier 1 that has rotated once, and a new electrophotographic image is formed on the image carrier 1 on which the visualized electrophotographic image has been formed. form an image.

The same applies to the case where the second electrophotographic image forming step is performed first.

The electrophotographic image newly formed in this way is developed by the developing device 47. During development at this time, the developing device 47 is arranged in a non-contact manner with the image carrier 1 in order to prevent the first developed electrophotographic image from being destroyed.

The developer attached to both electrophotographic images is transferred onto a sheet of paper by the transfer charger 49, and this sheet of paper is discharged onto the paper discharge tray 52 via the fixing device 51. An image corresponding to the original image and an image corresponding to the image written based on the image signal are formed on the ejected paper.

Note that the above-mentioned embodiment is merely an example, and various modifications can be made within the scope of the gist of the present invention. For example, the first polarity and the second polarity do not need to be so-called opposite polarities (positive, negative), and may be two types of levels within a range above and below an arbitrary reference potential. Also, depending on the nature of the image carrier,
It is also possible to invert the surface potential described above.

[Effects of the Invention] As is clear from the above description, in the image forming method of the present invention, an electrophotographic image is formed in the original unirradiated area during image exposure and the irradiated area corresponding to the image. is possible,
As a result, an electrophotographic image can be visualized with a single developing means, and this has excellent effects such as contributing to the multifunctionality of an image forming apparatus.

[Brief explanation of drawings]

The first figure is a schematic sectional view showing the structure of the image carrier, and the second figure is an explanatory diagram of the surface potential of the image carrier, and the third factor (α). (b) *(') is an explanatory diagram of the movement of charges in the first electrophotographic image forming step, FIG. 6(d) is an explanatory diagram of the change in surface potential in the first electrophotographic image forming step, and FIG. Figures 4 (α), (b), and (c) are explanatory diagrams of the movement of charges in the second electrophotographic image forming step, and Figure 4 (d) is an illustration of the surface potential in the second electrophotographic image forming step. Figure 5 is an explanatory diagram showing an example of the static eliminator, Figures 6 and 7 are explanatory diagrams of other static eliminators, and Figure 8 is an illustration of the first and second electrophotographic image formation. 1 is a schematic cross-sectional view showing an example of an image forming apparatus including steps. 1... Image carrier, 14... Conductive substrate, IB
...Photoconductive column layer, 1C...Insulating layer, 47...Development means. Ward 3 ((1) (b) (C) (d) (a) (b) (C) (d) 14 Figure 7

Claims (8)

[Claims] (1) An image carrier formed by laminating a bipolar photoconductive layer and an insulating layer is charged at a first polarity with respect to a reference potential, and then the image carrier is charged to a second polarity, and the image carrier is then charged to a second polarity. An electrophotographic image forming step of Ml in which an electrophotographic image is formed with a polarity of M2 by exposure, and the image carrier is charged with a second polarity with respect to a reference potential, and then the image carrier is charged with a polarity near the reference potential. and a second electrophotographic image forming step of forming an electrophotographic image with a second polarity on the irradiated portion of the original by irradiating the image carrier with a source corresponding to the image. An image forming method characterized by: (2) The image forming method according to claim 1, wherein the step of charging the image carrier with the first polarity in the first electrophotographic image forming step is a step of charging in a bright place. (3) In the first electrophotographic image forming step, the step of charging the image carrier with the first polarity is a step of exposing the image carrier to light in advance and charging while the photoconductive layer has sustained conductivity. An image forming method according to claim 1. (4) The image forming method according to claim 1, wherein the step of charging the image carrier with the second polarity in the second electrophotographic image forming step is a step of charging in a bright place. (5) In the second electrophotographic image forming step, the step of charging the image carrier with the second polarity is a step of exposing the image carrier to light in advance and charging while the photoconductive layer has sustained conductivity. An image forming method according to claim 1. (6) The first electrophotographic image forming step is performed by overlapping the electrophotographic image formed in the second electrophotographic image forming step after the electrophotographic image formed in the second electrophotographic image forming step is visualized. Image forming method described in section. (7) The second electrophotographic image forming step is performed by overlapping the electrophotographic image formed in the first electrophotographic image forming step after the electrophotographic image formed in the first electrophotographic image forming step is visualized. Image forming method described in section. (8) The image forming method according to claim 6 or 7, wherein the electrophotographic image is visualized by a developing means disposed in a non-contact manner with the image carrier.