JPS5898747A - Image forming method - Google Patents

Abstract

PURPOSE:To form a distinct image pattern-like toner image, which generates no ground fog, by using the first developing sleeve and the second developing sleeve. CONSTITUTION:The first developing sleeve 5 and the second developing sleeve 12 are used as each different developing device. In both of the developing sleeve, however, a magnet is placed suitably in the inside of the sleeve. To the first developing sleeve 5, DC bias is applied by an electric power supply 4, a picture is exposed and developed, and after that, ground fog is eliminated by the second developing sleeve 12 which has been grounded. In this case, the first developing sleeve 5 to which DC bias has been applied, and the second developing sleeve 12 which has been grounded are capable of selecting the relative moving direction of a photosensitive body 1 and the two developing devices 5, 12 by changing the application of the bias to each other by a switch 16, etc. By using such developing devices, it is possible to form a distinct image pattern-like toner image which generates no ground fog.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming method, and particularly to an image forming method for forming a toner image on a photoreceptor.

Conventionally, as a method of forming a toner image on a photoreceptor, the photoreceptor is uniformly charged and the photoreceptor is irradiated with original image light or signal-modulated image light from a traveling beam. 2. Description of the Related Art A method of forming an electrostatic latent image by creating a difference in charge density in an image pattern, and developing this with an insulating or conductive developer is widely known as an electrophotographic method.

When using an insulating developer, it is mixed with other particles and tribo-electrified on the developing sleeve, or it is tribo-electrified by contact with the developing sleeve, and the charged developer and the charge on the photoreceptor are combined. Coulomb force acting between the two causes the developer to adhere to the surface of the photoreceptor to form a visible image.

In addition, when using a conductive developer, the electric charge existing on the photoreceptor induces charges in the developer on the grounded developing sleeve that should pair with the charges on the photoreceptor and the electric charge on the photoreceptor. The applied Coulomb/force causes the developer to deposit on the photoreceptor surface to form a visible image.

When using either an insulating or conductive developer, so-called background fog may occur, but this often occurs when charges that should be removed during Ryotsu exposure remain. A positive or negative bias may be applied to the developing sleeve to prevent a potential difference from occurring between the two layers. The first method of this image forming method will be described below.

In addition, by irradiating the photoreceptor with image light in advance to form a conductive butter, and applying a DC bias between the developing sleeve and the conductive substrate/plate on which the photoreceptor is provided, the conductive butter is formed. There is a method (Japanese Patent Publication No. 48-43821) which forms a potential difference between the developer and the surface of the photoreceptor to form a toner image according to the above-mentioned surface conductivity pattern. This will be described as the second method.

Alternatively, as shown in FIG. 1, a photosensitive layer 1 is provided on a transparent conductive substrate in which a transparent conductive layer 2 and a transparent support 3 are laminated to form a photoreceptor, and a conductive magnetic developer 6 is uniformly formed by a magnetic field. A DC bias is applied from the power source 4 between the attached developing sleeve 5 and the substrate of the photoreceptor to form a uniform potential difference between the developer and the surface of the photoreceptor, and the developing sleeve and leap are By performing image exposure P from the transparent conductive substrate side of the photoreceptor at a position where the conductive developer is introduced to the photoreceptor surface, a toner image in the form of an image pattern can be formed on the photoreceptor surface. Hereinafter, this image forming method will be referred to as the third method.

The first method described here requires a complicated and expensive apparatus due to equipment such as control means, voltage generators, etc. involved in the process of charging, exposing, and developing, and is also less reliable.

Furthermore, since the second and third methods do not require the charging procedure required in the first method, the apparatus can be extremely simple compared to the first method. However, when a toner image is formed by the third method or a method similar to this method, the occurrence of background fog is unavoidable in principle in order to obtain sufficient image density. That is, in the third method, as shown in FIG. 2, the process of depositing the developer on the surface of the N-type photoreceptor is carried out between the developing sleeve 5, which has a magnet inside, and the transparent conductive layer 2, with the sleeve side facing upright. A conductive magnetic developer 6 is guided onto the surface of the photoreceptor while a DC bias is applied from the power source 4 such that a uniform potential difference is formed between the developer and the surface of the photoreceptor, and at the same time the transparent conductive substrate is Illuminates the image light from the side. As a result, a positive charge 7 is induced in the photo carrier 8 which is generated and moved in an image pattern within the photoreceptor 1, and a positive charge 7 is induced in the conductive/electrical developer 6 held in the sleeve, due to the Coulomb force, as shown in FIG. As shown in FIG. 2, developer 6 is deposited on the surface of the photoreceptor. In this case, even in the dark area, charges 9 and 10 are already induced by the capacitance of the area including the dark area photosensitive layer between the conductive developer and the transparent conductive substrate, and a Coulomb/force is applied. This causes a ground fog.

Note that although an N-type photoreceptor is used as an example here, similar results can be obtained even if other photoreceptors are used by selecting the polarity of the DC bias applied between the skeleton sleeve and the transparent conductive substrate. Although the absolute toner density in the sleeve and background fogging areas can be made sufficiently low, even in the so-called bright areas of the image pattern, sufficient photocarriers are not generated within the photoreceptor, and as a result, they adhere to the image pattern. This means that the entire toner image cannot have sufficient density.

The second method utilizes the property that the conductive developer is difficult to adhere to the conductive surface formed on the surface of the photoreceptor by irradiating the surface with light. Since a relatively small amount of developer adheres according to the image pattern, similar to the background fog mentioned in the third method, it is the same as the Coulomb force that acts between the developer attached to the desired area and the conductive substrate on which the photoreceptor is provided. If the Coulomb force is less than that, it will adhere to the surface of the photoreceptor and cause background fog.

Therefore, although the second method, the third method, or a method similar to this method has advantages over the first method, it is not widely used as a method for forming a toner image on the surface of a photoreceptor. As stated here, the ground cover that is thought to occur in principle is 1 island.
) is a factor.

The present invention uses a sufficiently advantageous method, such as the second method or the third method, to deposit a conductive magnetic developer on the surface of a photoreceptor, thereby producing a clear image pattern without background fogging. An object of the present invention is to obtain an image forming method for forming a toner image.

As a means for achieving the above object, there is provided a developer having conductivity and magnetism, a first developer holding member having a magnet inside and holding the developer on its outer surface, and electrically connected to the developer. a first electrode, conductive and magnetic particles,
A second developer holding member having a magnet inside and holding the particles on the outer surface, a second electrode connected to the particles by electrowaxing, and a photoreceptor having a conductive substrate are used. By introducing the developer to the surface of the photoreceptor and applying a DC bias between the first electrode and the photoreceptor, a uniform potential difference is formed between the surface of the photoreceptor and the developer. a first step of attaching a developer to the surface of the photoreceptor; a second step of introducing the particles to the surface of the photoreceptor and keeping the second electrode and the conductive substrate of the photoreceptor at approximately the same potential; It is characterized by comprising a step of irradiating the photoreceptor with image light simultaneously with or prior to the step of.

The embodiments shown in the drawings will be described below. FIG. 4 shows the state of the toner image and charge on the N-type photoreceptor developed by the first development three-shield.

In the exposed bright area of the figure, the positively charged developer 6 is attached to the photoconductor surface by Coulomb force within the photoconductor or at a distance sufficiently close to the negative charge e existing on the photoconductor surface. . In addition, in the unexposed dark areas of the figure, the positively charged developer 6' adheres to the surface of the photoreceptor due to the Coulomb force with the negative charge C on the conductive substrate 2, resulting in background fog. -ru. The surface of the photoreceptor in this state is grounded and reproduced by the ninth developing sleeve 12.

Look at this lol! In the sIs diagram shown in FIG. 5, 11 is a conductive particle attached on the grounded second developing sleeve 12, and is the same conductive magnetic developer attached on the first developing sleeve 5. 6, or other conductive particles may be used. Usually, conductive magnetic developers used in electrophotography, iron powder ferrite, etc., with particle sizes similar to or slightly larger than those of the developer are optimal. .

Negative charges are induced in the conductive developer 11 adhering to the second developing sleeve 12 as it approaches the positively charged developer adhering to the surface of the photoreceptor. As a result, a Coulomb force acts between the positively charged developer 6 on the surface of the V photoreceptor and the developer 11 adhering to the second developing sleeve 12. In FIG. 4, if the positively charged developer 6 is attached to the surface of the photoreceptor due to strong Coulomb force at a sufficiently close distance to the negative charge e existing within the photoreceptor or on the surface of the photoreceptor, the second Even if the negatively charged developer 11 adhering to the developing sleeve 12 approaches, the positively charged developer 6
It is held on the surface of the photoreceptor by strong Coulomb force. Of course, the positively charged developer on the surface of the photoreceptor is affected by mechanical forces other than electrostatic force, such as magnetic force or contact, due to the developer attached to the second developing sleeve or its developer. Some of them may not be retained on the surface of the photoreceptor because they may be subjected to the impact of time, but in reality, they are retained as they are because the Coulomb force with the negative charge existing within the photoreceptor or on the surface of the photoreceptor is sufficiently strong. There are many.

However, in FIG. 4, the negative charge e on the conductive substrate
The so-called background-fogging developer 6' that adheres to the surface of the photoreceptor due to the relatively weak radiation is first of all the developer on the second developing sleeve 12 in which negative charges have been induced. The second developing sleeve 12 is easily moved from the surface of the photoreceptor by the Coulomb force with the photoreceptor 11 or by the other forces mentioned above.
It will be moved up. As a result, a toner image with a clear image pattern without background fog can be obtained.

Although the second developing sleeve 12 which is grounded is taken as an example here, the second developing sleeve 2 has a DC or AC bias which is sufficiently smaller than the DC bias applied to the first developing sleeve 5. An effective effect can also be obtained by applying .

Although the third method has been described above as an example, the second method can also be applied in the same way by taking into consideration a dynamic force.

Hereinafter, a specific example of the configuration of an apparatus using the image forming method of the present invention will be described.

Embodiment 1) As shown in FIG. 6, the first developing sleeve 5 and the second developing sleeve 12 are separate developing devices, and each developing device including the developing sleeve has a different shape. Good too. However, it goes without saying that all of the developing sleeves have magnets appropriately arranged inside the sleeve. A DC bias is applied to the first developing sleeve 5 by the power source 4, the image is exposed and developed, and after death, the background fog is removed by the grounded second developing sleeve 12.

In this case, the first developing sleeve 5 to which DC bias is applied and the second developing sleeve 12 which is grounded can be connected to the photoreceptor and the two developing devices by switching the bias application from switch 16 etc. to b. The relative direction of movement can be selected.

Embodiment 2) In FIG. 7, the first developing sleeve 5 and the second Q developing sleeve 12 are used as one developing device, and the conductive magnetic developer can be shared. In this case, an insulating layer 13 is provided between the first developing sleeve 5 and the second developing sleeve 12, so that short circuits due to conductive developer can occur between the developers adhering to each sleeve. This is an example of taking measures to prevent this from occurring.

Embodiment 3) An apparatus similar to the above-mentioned Example 1, in which one challenge sleeve serves both as the first developing sleeve and the second developing sleeve. That is, first, a DC bias is applied to the developing sleeve to perform image development by image exposure as the first developing sleeve, and then it is grounded and used as the second developing sleeve, and the same photoreceptor surface that was developed with the first developing sleeve is again used. The background fog is removed by developing the image.

Embodiment 4) FIG. 8 shows conductive layers 15a-15b on one developing sleeve.
An example of obtaining substantially the same effect as having a first developing sleeve and a second developing sleeve by arranging the insulating layer 14. However, in this case, the developer adheres to the sleeve in the form of a brush, and the resistance is low in the direction in which the brush extends, but it is relatively high in the nine directions along the circumference of the sleeve, so As shown in Figure 8, the insulating layer 14' is connected to the electrode bs:
By making it wider than b, it is also possible to prevent a short circuit with the sleeve.

In the examples mentioned above, the rotation direction of the magnet in the developing sleeve can be freely selected.

Furthermore, in Examples 1 to 3, the developing sleeve may not rotate or may rotate in any direction.

stomach. It is sufficient to use a developing device having a structure including a developer holding member having a magnet for holding a conductive magnetic developer, and an electrode capable of supplying the necessary charge to the developer. It is. Furthermore, the conductive magnetic developer or conductive magnetic particles used in the present invention may be of relatively low resistance, or may be of relatively high resistance as disclosed in Japanese Patent Publication No. 53-31136. As disclosed in 2003, during development, it is preferable to use the developing sleeve or the internal magnet with lower apparent resistance than the high-speed rotation of the developing sleeve or the internal magnet.

Regarding the direction of rotation of the magnet, at the contact surface between the developer and the photoconductor, the developer to which a DC bias has been applied is rotated so that it is conveyed in the same direction as the direction of movement of the photoconductor. A developer pool is created on the upstream side, and because the developer has a relatively weak magnetic force in this developer pool, it often adheres to the surface of the photoreceptor, and furthermore, on the downstream side, a relatively strong magnetic force does not act on the developer. This prevents excess developer from adhering to the photoreceptor and provides clear images. In addition, since the developer is transported in the opposite direction to the moving direction of the photoreceptor at the contact surface between the developer and the photoreceptor, the rounded magnetic developer is more likely to adhere to the surface of the photoreceptor, increasing the density of the Chinese image. Sometimes it's good for you. In addition, it is better to rotate the magnet so that the photoreceptor is transported in the same direction as the photoreceptor at the contact surface between the developer and the photoreceptor to remove background fog, which is not applied with a bias.

For example, in the case shown in Example 4 above, considering the reasons mentioned above, it is better to select a direction in which the magnet rotates so that the developer is conveyed in the same direction as the direction of movement of the photoreceptor. be.

Also, when developing to remove background fog, even if weak light hits the photoreceptor, it will not have a big effect,
It is preferable to carry out the process in a dark place to avoid unnecessary charge injection due to the application of an electric field to the photosensitive layer due to the charge of the background-fogging developer.

Next, specific examples of the present invention will be described. A mixture of Cu-activated CdS powder and acrylic resin at a weight ratio of 100 Nia was dispersed in toluene, applied in one go, and dried at 70'C for 30 minutes to form a photoreceptor. As a conductive magnetic developer, TYPE 355VQCIMAG from Minnesota, Myni/G, & Manufacturing Co., Ltd.
Use INGPOWDER. The developing device is equipped with a stainless steel developing sleeve with a magnet placed inside, and the internal magnet is rotated along the inside of the sleeve at a rotational speed of about 1400 rq. First, a DC bias is applied between the developing sleeve and the transparent conductive layer so that the developing sleeve side is positive, and approximately 4
A flash is used to expose a position where the photoreceptor and the developer on the developing sleeve are in contact with each other with an exposure amount of ux@sec. During this time, the photoreceptor is 60 tm/s relative to the developing device.
It is moving at a speed of ec. When the applied DC bias is 100V, the background fog is thin in the unexposed areas, but the actual image density is low in the exposed areas.When the DC bias t'aoov is applied, the exposed areas have sufficient density1 But the background fog is also thick.Here, 300V
The DC bias is turned off by a switch to ground the developing sleeve, and the photosensitive plate is moved in the opposite direction to bring the developer on the developing device sleeve into contact again with the already developed portion. As a result, a clear image without background blur was obtained.

As mentioned above, the present invention allows a clear toner image to be obtained in an extremely simple method in electrophotography, and has the effect of significantly reducing the cost of equipment for forming toner images compared to the conventional image forming method K. . Furthermore, (1) the developer on the first developer holding member is made to adhere to the surface of the photoreceptor, and the second developer holding member is able to reliably remove background fog; During the developer adhesion process by the holding member, a high DC bias is applied without worrying about background fog, but there is no need to control the bias in advance to the semicircular cord, and control fI! −
There is easy 'C. Furthermore, an inexpensive power source with relatively poor stability can be used as the power source for the DC bias.

(2) Since a high bias can be applied, sufficient photocarriers can be generated inside the photoreceptor with a small amount of exposure, and a clear image can be obtained with a small amount of exposure. It will be done.

[Brief explanation of drawings]

1, 1112, and 3 are schematic diagrams of the process in which the developer adheres to the surface of the photoconductor, and FIG. 4 is a schematic diagram showing the state in which the developer adheres to the surface of the photoconductor through the process shown in FIG. FIG. 5 is a schematic diagram showing the state when a photoreceptor is guided onto grounded particles, and FIGS. 6, 7, and 8 show specific configuration examples of an apparatus for carrying out the method of the present invention. FIG. 1 is a photosensitive layer, 2 is a transparent conductive layer, 3 is a transparent support, 4 is a power source, 5 is a first developing sleeve, 6 and 11 are developers, and 7.
9 and 10 are charges, 8 is a photo carrier, and 12 is a second developing sleeve. Figure 4 Figure 3 Figure 2 Figure 1 Figure 5

Claims (6)

[Claims] (1) A developer having conductivity and magnetism, a first developer holding member having a magnet inside and holding the developer on its outer surface, a first electrode electrically connected to the developer; A photosensitive material having conductive and magnetic particles, a second developer holding member having an internal PC magnet and holding the particles on an outer surface, a second electrode electrically connected to the particles, and a conductive substrate. The developer is guided to the surface of the photoreceptor using a body, and a DC bias is applied between the first electrode and the photoreceptor, thereby uniformly distributing the developer between the surface of the photoreceptor and the developer. a first step of forming a potential difference to cause the developer to adhere to the surface of the photoreceptor; and a second step of guiding the particles to the surface of the photoreceptor and keeping the second electrode and the conductive substrate of the photoreceptor at approximately the same potential. and a step of irradiating the photoreceptor with image light simultaneously with or prior to the first step. (2) The image forming method according to claim (1), wherein the conductive and magnetic developer and the conductive and magnetic particles are made of the same substance. (3) The image forming method according to claim (1) or (2), wherein the second developer holding member also serves as the first developer holding member. (4) Claims (1) The first electrode is also used as the second electrode by controlling the DC bias to the first electrode.
)・The image forming method described in (2) or (3). (5) The image forming method according to claim (1), in which the developing brush is placed inside the photoreceptor while it is in contact with the photoreceptor during exposure. (6) The image forming method according to claim (1), wherein the magnets in the first and second developer holding members are rotated in a direction to convey the developer in the same direction as the moving direction of the photoreceptor.