JP2002103670A - Image forming device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To further reduce the size of an image forming apparatus, further reduce the number of parts to make a simpler and less expensive configuration, and more stably write an electrostatic latent image. Do. A writing electrode of a writing device is supported by a flexible base material having soft elasticity. Then, an electrostatic latent image is written on the latent image carrier 2 by charging or discharging by the writing electrode 3b on the latent image carrier 2 which has been brought into a uniform charge state by the latent image carrier uniform charge control device 7. The electrostatic latent image is developed by the developing device 4, and the developer image is transferred to the transfer material 5 such as paper by the transfer device 6. Writing device 3
Since the writing electrode 3a is used, the device is small and simple.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an image forming apparatus for forming an image by forming an electrostatic latent image on a latent image carrier by a writing member of a writing device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrostatic copying machine or a printer, generally, the surface of a photoconductor is uniformly charged by a charging device, and a laser beam is applied to the surface of the uniformly charged photoconductor. Alternatively, an electrostatic latent image is written on the surface of the photoconductor by exposing light of an exposure device such as LED lamp light. Then, the electrostatic latent image on the surface of the photoconductor is developed by a developing device to form a developer image on the surface of the photoconductor, and the developer image is transferred to a transfer material such as paper by a transfer device, and the image is formed. Has formed. In such a conventional general image forming apparatus, the exposing device, which is a writing device for an electrostatic latent image, is constituted by a laser light generating device, an LED lamp light generating device, or the like. And it has a complicated configuration.

Therefore, as an apparatus for writing an electrostatic latent image, an image forming apparatus for writing an electrostatic latent image on the surface of a latent image carrier using electrodes without using laser light or LED lamp light is disclosed in Japanese Patent Publication No. Sho 63 (1988).
-45014. The image forming apparatus disclosed in this publication includes a multi-stylus having a large number of needle electrodes, and the needle electrode of the multi-stylus is simply brought into contact with the inorganic glass layer on the surface of the latent image carrier. Then, when a voltage is applied to the corresponding stylus electrode of the multi-stylus according to the input signal of the image information, the stylus electrode forms an electrostatic latent image on the latent image carrier. According to the image forming apparatus disclosed in this official gazette, since the conventional exposure apparatus is not used as the writing apparatus, the image forming apparatus has a small and relatively simple configuration.

Further, by controlling the ions generated by the corona discharger at the tip of the insulating substrate by an ion control electrode which is not in contact with the latent image carrier, an electrostatic latent image is formed on the latent image carrier. An image forming apparatus to be written is disclosed in
No. 6206 proposes this. Even in the image forming apparatus disclosed in this publication, the exposure apparatus is not used as the writing device, so that the image forming apparatus has a small and relatively simple configuration.

[0005]

However, in the image forming apparatus disclosed in the above-mentioned official gazette, a large number of needle electrodes of the multi-stylus are simply brought into contact with the inorganic glass layer on the surface of the latent image carrier. In addition, it is difficult to bring a large number of needle electrodes into stable contact with the inorganic glass layer on the surface of the latent image carrier. For this reason, it is difficult to stably charge the surface of the latent image carrier, and it is difficult to obtain a good image.

Further, in order to prevent the surface of the latent image carrier from being damaged by the contact of a large number of needle electrodes, it is necessary to provide an inorganic glass layer on the surface of the latent image carrier. It gets complicated. In addition, since the inorganic glass layer has extremely good physical adsorption water characteristics, water is well adsorbed on the surface of the inorganic glass, and the electric conductivity of the glass surface is increased by the adsorbed water, so that the charge of the latent image carrier is reduced. Because of the leakage, it is necessary to provide a means for drying the surface of the latent image carrier on which moisture is adsorbed to prevent the influence of the physically adsorbed water. Therefore, there is a problem that not only the device becomes larger, but also the number of parts increases, the configuration becomes more complicated, and the cost becomes higher.

[0007] Further, since a large number of needle electrodes are discharged,
There is also a problem that ozone (O ₃ ) is likely to be generated. This ozone, not only to generate a rust in the component in the apparatus, nitric acid generated reacts with NO _x (HN
O ₃ ) may cause the resin component to melt. In addition, there is a possibility that an odor is generated by ozone. For this reason, ozone must be discharged from the inside of the device. For that purpose, it is necessary to provide a duct and an ozone filter to provide a sufficient exhaust system, which not only increases the size of the device, but also increases the number of parts and increases the configuration. It becomes more complicated and expensive.

In the image forming apparatus disclosed in the above-mentioned publication, the ion control electrode controls the ions generated by the corona discharger, and does not directly inject the electric charge into the latent image carrier. Not only does the image forming apparatus have to be large, but also the configuration is extremely complicated. Moreover, because of the charging by ions,
It is difficult to stably write an electrostatic latent image on a latent image carrier. Further, since ozone is basically generated due to generation of ions, a problem similar to that of the image forming apparatus disclosed in the above-mentioned official gazette occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and an object of the present invention is to further reduce the number of parts and to further reduce the number of parts to achieve a simpler and cheaper configuration. Another object of the present invention is to provide an image forming apparatus capable of writing an electrostatic latent image more stably. Another object of the present invention is to provide an image forming apparatus capable of further suppressing generation of ozone.

[0010]

In order to solve this problem, the present invention is directed to a latent image carrier on which an electrostatic latent image is formed, and the electrostatic latent image is formed on the latent image carrier. A writing device for writing; and a developing device for developing the electrostatic latent image on the latent image carrier, wherein the developing device writes the electrostatic latent image written on the latent image carrier by the writing device. A writing member for writing the electrostatic latent image on the latent image carrier, and a flexible base material supporting the writing member. And characterized in that: The invention according to claim 2 is characterized in that the writing member is constituted by a writing electrode.

Further, the invention according to claim 3 is characterized in that the writing member is brought into contact with the latent image carrier with a small pressing force by the elastic force of the substrate. Further, in the invention according to claim 4, the base member has an insulating layer, and the writing member is brought into contact with the electrostatic latent image with a small pressing force by the elastic force of the base member. In this case, the latent image carrier is brought close to the latent image carrier. Further, in the invention according to claim 5, the writing device and the developing device are provided for each color of black, yellow, magenta, and cyan,
It is characterized in that the developer images of the respective colors are formed on the latent image carrier by being superimposed by the writing device and the developing device of the respective colors. Further, the invention of claim 6 provides the latent image carrier, the writing device, and the developing device for each color of black, yellow, magenta, and cyan, so that the image forming apparatus for each of these colors becomes tandem. It is characterized by being arranged. Further, the invention according to claim 7 is characterized in that an intermediate transfer device is provided for intermediately transferring a developer image for each color by the image forming apparatus for each color.

[0012]

In the image forming apparatus according to the present invention, the writing member is supported by the flexible substrate, so that the position of the writing member with respect to the latent image carrier can be set flexibly. Become so. Accordingly, the writing of the electrostatic latent image on the latent image carrier by the writing member is performed more stably, so that a good image can be obtained reliably and with high accuracy.

Further, the flexible substrate allows the writing electrode to come into contact with the latent image carrier with a small pressing force or to come closer to the latent image carrier without fail. The spatial gap with the image carrier becomes extremely small. This reduces the chance of unnecessary ionization of the air in the spatial gap, so that the generation of ozone is further suppressed and an electrostatic latent image can be formed at a low potential.

In particular, according to the second aspect of the present invention, only a writing electrode is used as a writing member, and a conventional large-sized laser light generating device, LED lamp light generating device, and the like are not required. . Therefore, the size of the apparatus is further reduced, and the number of parts is further reduced, so that a simpler and less expensive image forming apparatus can be obtained. According to the third aspect of the present invention, since the writing member is only in contact with the latent image carrier with a small pressing force, damage to the latent image carrier by the writing electrode is prevented, and the latent image carrier is prevented from being damaged. Durability is improved.

Further, in the invention according to claim 4, the writing member is stabilized with a predetermined gap from the latent image carrier by bringing the insulating layer provided on the base into contact with the latent image carrier. And be brought close together. Therefore, the writing of the electrostatic latent image by the writing member can be performed stably and with high accuracy. Furthermore, since the writing member is only in the vicinity of the latent image carrier, the damage of the latent image carrier by the writing member is prevented, and the durability of the latent image carrier is improved. Further, even when the insulating layer is in contact with the latent image carrier, since the insulating layer is provided on the flexible base material, the pressing force with which the insulating layer presses the latent image carrier can be set extremely small. Further, damage to the latent image carrier by the flexible insulating layer is suppressed.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically showing a basic configuration of an embodiment of an image forming apparatus according to the present invention. As shown in FIG. 1, an image forming apparatus 1 according to the present invention
Is a latent image carrier 2 on which an electrostatic latent image is formed, a writing device 3 that contacts the latent image carrier 2 and writes an electrostatic latent image on the latent image carrier 2, Developing device 4 for developing the above electrostatic latent image with the developer carried and conveyed by developer carrier 4a
And a transfer device 6 for transferring the developer image on the latent image carrier 2 developed by the developing device 4 onto a transfer material 5 such as paper, and transferring the charge remaining on the latent image carrier 2 after transfer. The apparatus further includes at least a latent image carrier uniform charge control device 7 that removes electricity or charges the latent image carrier 2 after transfer to make the latent image carrier 2 a uniform charge state. In the following description, all the latent image carriers 2 are described as being grounded, but this is for convenience of description, and the present invention is limited to the case where the latent image carrier 2 is grounded. is not.

The writing device 3 is an FPC (Flexible Print C).
An insulating material such as ircuit (hereinafter abbreviated as FPC) or PET (polyethylene terephthalate, abbreviated as PET) or the like, which has a high insulation property, is relatively soft and elastic, and is supported by the base material 3a. Further, a writing electrode (corresponding to a writing member of the present invention) 3b, which is lightly pressed on the latent image carrier 2 with a weak elastic restoring force due to the bending of the base material 3a and writes the electrostatic latent image by contacting the latent image carrier 2, is formed. Have.

In the image forming apparatus 1 configured as described above, the latent image carrier 2 is controlled by the latent image carrier uniform charge control device 7.
After the upper portion is brought into the uniformly charged state, the electrostatic latent image is written on the latent image carrier 2 in the uniformly charged state by the writing device 3 in contact with the latent image carrier 2. Then, the electrostatic latent image on the latent image carrier 2 is developed with the developer of the developing device 4, and the developer image is transferred to the transfer material 5 by the transfer device 6. In the present invention, a state in which the charge on the latent image carrier 2 is eliminated and neither (+) nor (-) is uniformly on the latent image carrier 2 is also a uniform charge state. And

FIG. 2 is a view showing a basic process of image formation in the image forming apparatus 1 of the present invention. As a basic process of image formation in the image forming apparatus 1 of the present invention,
(1) Uniform charge removal-Contact charge writing-Regular development, (2) Uniform charge removal-Contact charge writing-Reversal development, (3) Uniform charge-Contact charge removal writing-Regular development, and (4) One There are four image forming processes, namely, charge removal, contact charge removal writing, and reversal development. Hereinafter, these image forming processes will be described.

(1) Uniform charge elimination-contact charging writing-regular development As an example of this image forming process, there is a process shown in FIG. As shown in FIG. 2A, in this image forming process, a photoreceptor 2a is used as a latent image carrier 2, and a neutralization lamp 7a is used as a latent image carrier uniform charge control device 7. . The writing electrode 3b of the writing device 3 comes into contact with the photoconductor 2a and (+) charges the image portion of the photoconductor 2a to write an electrostatic latent image on the photoconductor 2a. Further, a bias voltage in which an alternating current is superimposed on a direct current (-), for example, is applied to the developing roller 4a of the developing device 4 as in the related art, and the developing roller 4a is charged with the developer 8 charged to the negative (-). Is conveyed toward the photoreceptor 2a. It should be noted that a DC-only bias voltage (-) can be applied to the developing roller 4a.

In the image forming process of this example, the charge on the surface of the photosensitive member 2a is removed by the charge removing lamp 7a, and the photosensitive member 2a is brought into a uniform charge state close to 0 V from which the charge has been removed. The image portion on the photoconductor 2 a is (+) charged by the writing electrode 3 b of the writing device 3, and this photoconductor 2
The electrostatic latent image is written on a. Then, the (-) charged developer 8 conveyed by the developing roller 4a of the developing device 4 adheres to the (+) charged image portion of the photoconductor 2a, and the electrostatic latent image is regularly developed.

As another example of the image forming process, there is a process shown in FIG. As shown in FIG. 2B, in this image forming process, a dielectric 2b is used as the latent image carrier 2, and a charge eliminating roller 7b is used as the latent image carrier uniform charge control device 7. . A DC bias voltage of, for example, (-) is applied to the developing roller 4a of the developing device 4 as in the related art. Incidentally, a bias voltage in which alternating current is superimposed on direct current (-) can be applied to the developing roller 4a. Further, the charge removing roller 7b
, An AC bias voltage is applied. The other configuration of the image forming process of this example is the same as the example shown in FIG. In the image forming process of this example,
The charge removing roller 7b is in contact with the dielectric 2b, and the charge of the dielectric 2b is removed by the charge removing roller 7b, so that the dielectric 2b is brought into a uniform charge state close to 0 V from which the charge has been removed. The subsequent image forming operation is the same as the example shown in FIG. 2A except that the photoconductor 2a is changed to the dielectric 2b.

(2) Uniform charge removal-contact charging writing-reversal development As an example of this image forming process, there is a process shown in FIG. As shown in FIG. 2C, in this image forming process, as in the example shown in FIG. 2A, the photosensitive member 2a is used as the latent image carrier 2 and the latent image carrier 2 A charge eliminating lamp 7a is used as the charge control device 7. The writing electrode 3b of the writing device 3 comes into contact with the photoconductor 2a and charges the non-image portion of the photoconductor 2a (-). The other configuration of the image forming process of this example is the same as the example shown in FIG.

In the image forming process of this embodiment, the charge of the photosensitive member 2a is removed by the charge removing lamp 7a, and the photosensitive member 2a is brought into a uniform charge state close to 0 V from which the charge has been removed. The non-image portion on the photoconductor 2a is (-) charged by the writing electrode 3b of the device 3, and an electrostatic latent image is written on the photoconductor 2a. Then, the (−) charged developer 8 conveyed by the developing roller 4 a of the developing device 4 adheres to the (−) uncharged image portion near 0 V on the photoreceptor 2 a, and the electrostatic latent image is reversely developed. You.

As another example of the image forming process, there is a process shown in FIG. As shown in FIG. 2D, in this image forming process, the dielectric 2b is used as the latent image carrier 2 as in the example shown in FIG. As the control device 7, a charge eliminating roller 7b is used. Further, the writing electrode 3b of the writing device 3 comes into contact with the dielectric 2b to charge the non-image portion of the dielectric 2b (-). The other configuration of the image forming process of this example is the same as the example shown in FIG. In the image forming process of this example, the charge removing roller 7b is in contact with the dielectric 2b, and the charge of the dielectric 2b is removed by the charge removing roller 7b, and the dielectric 2b is discharged.
b is brought to a uniform charge state close to 0 V with the charge removed. The subsequent image forming operation is the same as that of the example shown in FIG.

(3) Uniform charging, contact erasure writing, and regular development As an example of this image forming process, there is a process shown in FIG. As shown in FIG. 2E, in this image forming process, a photosensitive member 2a is used as the latent image carrier 2, and a charging roller 7c is used as the latent image carrier uniform charge control device 7. . This charging roller 7c
Is applied with a bias voltage in which an alternating current is superimposed on a direct current of (+), and the charging roller 7c moves (+) on the photosensitive member 2a.
To be uniformly charged. The charging roller 7
A bias voltage of (+) DC only can be applied to c. The writing electrode 3b of the writing device 3 is
a, the (+) charge of the non-image portion of the photosensitive member 2a is removed. The other configuration of the image forming process of this example is the same as the example shown in FIG.

In the image forming process of this embodiment, the charging roller 7c is brought into contact with the photosensitive member 2a, and the photosensitive member 2a is charged (+) by the charging roller 7c to be in a uniform charge state of a predetermined voltage. Then, the (+) charge of the non-image portion on the photoconductor 2a is removed by the writing electrode 3b of the writing device 3, and an electrostatic latent image is written on the photoconductor 2a. And
Conveyed by the developing roller 4a of the developing device 4 (-)
The charged developer 8 adheres to the (+) charged image portion of the photoconductor 2a, and the electrostatic latent image is developed normally.

As another example of the image forming process, there is a process shown in FIG. As shown in FIG. 2 (f), in this image forming process, a dielectric 2b is used as the latent image carrier 2, and a charging corona discharger 7d is used as the latent image carrier uniform charge control device 7. Have been. Although not shown, the charging corona discharger 7d includes:
DC bias voltage of (-) or (-)
A bias voltage in which an alternating current is superimposed on a direct current is applied.
Further, the writing electrode 3b of the writing device 3 comes into contact with the dielectric 2b to eliminate the (-) charge in the non-image portion of the dielectric 2b. Further, a DC bias voltage of (+) is applied to the developing roller 4a, and the developing roller 4a conveys the developer 8 charged to (+) toward the dielectric 2b. The developing roller 4a has (+)
Alternatively, a bias voltage in which the direct current and the alternating current are superimposed can be applied. The other configuration of the image forming process of this example is the same as the example shown in FIG.

In the image forming process of this example, after the dielectric 2b is charged (-) by the charging corona discharger 7d to a uniform state of a predetermined voltage, the writing device 3
Of the non-image portion on the photoreceptor 2a by the writing electrode 3b
The charge is removed, and an electrostatic latent image is written on the dielectric 2b. Then, the (+) charged developer 8 conveyed by the developing roller 4a of the developing device 4 adheres to the (−) charged image portion of the dielectric 2b, and the electrostatic latent image is regularly developed.

(4) Uniform charging-contact charge removing writing-reversal development As an example of this image forming process, there is a process shown in FIG. 2 (g). As shown in FIG. 2G, in this image forming process, a photosensitive member 2a is used as the latent image carrier 2, and a charging roller 7c is used as the latent image carrier uniform charge control device 7. . This charging roller 7c
Is applied with a bias voltage in which an alternating current is superimposed on a direct current (−), and the charging roller 7c moves on the photoconductor 2a (−).
To be uniformly charged. The charging roller 7
It is also possible to apply a (−) DC only bias voltage to c. The writing electrode 3b of the writing device 3 is
a, the (-) charge of the image portion of the photosensitive member 2a is eliminated. The other configuration of the image forming process of this example is the same as the example shown in FIG.

In the image forming process of this embodiment, the charging roller 7c is brought into contact with the photosensitive member 2a, and the photosensitive member 2a is charged (-) by the charging roller 7c to a uniform charge state of a predetermined voltage. The (-) charge of the image portion on the photoconductor 2a is eliminated by the writing electrode 3b of the writing device 3, and an electrostatic latent image is written on the photoconductor 2a. Then, the (-) charged developer 8 transported by the developing roller 4a of the developing device 4 adheres to the (-) non-charged image portion of the photoconductor 2a, and the electrostatic latent image is reversely developed.

As another example of the image forming process, there is a process shown in FIG. As shown in FIG. 2H, in this image forming process, a dielectric 2b is used as the latent image carrier 2, and a charging corona discharger 7d is used as the latent image carrier uniform charge control device 7. Have been. Although not shown, the charging corona discharger 7d includes:
DC bias voltage of (+) or (+) as before
A bias voltage in which an alternating current is superimposed on a direct current is applied.
Another configuration of the image forming process of this example is the same as that of FIG.
This is the same as the example shown in FIG.

In the image forming process of this example, after the dielectric 2b is charged (+) by the charging corona discharger 7d to have a uniform charge state of a predetermined voltage, the writing device 3
The (+) charge of the image portion on the photoconductor 2a is eliminated by the writing electrode 3b, and an electrostatic latent image is written on the dielectric 2b. Then, the (+) charged developer 8 transported by the developing roller 4a of the developing device 4 adheres to the (+) uncharged image portion of the dielectric 2b, and the electrostatic latent image is reversely developed.

FIG. 3 explains the principle of writing an electrostatic latent image by charging or discharging the writing electrode 3b of the writing device 3.
(A) is an enlarged view of a contact portion between the writing electrode 3b and the latent image carrier 2, (b) is an electrical equivalent circuit diagram of this contact portion, and (c) to (f) each parameter and the latent image carrier. FIG. 4 is a diagram showing a relationship with a surface potential of a body 2. As shown in FIG. 3 (a), the latent image carrier 2 is made of a conductive material such as aluminum, and has a grounded base 2c and an insulative charged body formed on the outer periphery of the base 2c. And a layer 2d. The writing electrode 3b supported by the base material 3a made of FPC or the like of the writing device 3 is in contact with the charged layer 2d with a predetermined small pressing force as described above, and the latent image carrier 2 is Is moving (rotating) at the speed v. This small pressing force
With a width of 300 mm and a pressing force of 10 N or less, that is, a linear pressure of 0.0
3 N / mm or less indicates the contact between the writing electrode 3 b and the latent image carrier 2 or the proximity of the writing electrode 3 b to the latent image carrier 2 (the gap between the writing electrode 3 b and the latent image carrier 2). It is preferable from the viewpoint of stabilization and stabilization of charge injection or discharge. From the viewpoint of abrasion, it is desirable to reduce the linear pressure as much as possible while maintaining the state of maintaining stable contact.

[0035] The writing electrodes 3b, a predetermined high voltage V ₀ or a predetermined low voltage V ₁ is adapted to be applied selectively switched through the substrate 3a (±, as described above
High voltage means a voltage with a high absolute value,
The low voltage has the same polarity as the high voltage and has a low absolute value or 0V. In the description of the present invention in this specification, all of the low voltage is a ground voltage, so in the following description, the high voltage V _{0 is referred} to as a predetermined voltage V ₀ ,
The low voltage V ₁ that the ground voltage V _1. It goes without saying ground voltage V ₁ is 0V. ).

That is, at the contact portion (nip portion) between the writing electrode 3b and the latent image carrier 2, an electric equivalent circuit shown in FIG. 3B is formed. In FIG. 3B,
R indicates the resistance of the writing electrode 3b, and C indicates the capacitance of the latent image carrier 2. Resistance R of the writing electrode 3b is the A side - is adapted to be selectively switched for connection to a predetermined voltage V ₀ or the ground voltage V ₁ of the B-side ().

In the equivalent circuit, the writing electrode 3b is connected to the A side, and the resistance R of the writing electrode 3b and the latent image carrier 2 when a predetermined voltage V ₀ (−) is applied to the writing electrode 3b. the relationship between the surface potential of FIG. 3 (c) to the next predetermined voltage V ₀ the surface potential of the latent image carrier 2 is constant in the region resistance R of the writing electrode 3b is small as shown by the solid line, the writing electrodes When the resistance 3b is larger than a predetermined value, the absolute value of the surface potential of the latent image carrier 2 decreases. On the other hand, the relationship between the resistance R of the writing electrode 3b and the surface potential of the latent image carrier 2 when the writing electrode 3b is connected to the B side and the writing electrode 3b is grounded is shown in FIG. approximately ground voltages V ₁ becomes the resistance R is the surface potential of the latent image carrier 2 is small region of a certain writing electrode 3b as indicated by the dotted line, the resistance R of the writing electrode 3b is a larger area than a predetermined value Then, the absolute value of the surface potential of the latent image carrier 2 increases.

[0038] In the region which is a predetermined voltage V ₀ or constant at the ground voltage V ₁ of the resistor R is small surface potential of the latent image carrier 2 is constant writing electrode 3b, as shown in FIG. 4 (a) Writing electrode 3b contacting latent image carrier 2 and latent image carrier 2
Is injected directly from the lower voltage to the higher voltage with the charged layer 2d. That is, the latent image carrier 2 is charged or eliminated by charge injection. In a region where the resistance R of the writing electrode 3b is large and the surface potential of the latent image carrier 2 starts to change, the charge or static elimination of the latent image carrier 2 due to charge injection gradually decreases, and the writing electrode 3b The resistance R of FIG.
As shown in (b), a discharge is generated between a later-described conductive pattern of the substrate 3a and the latent image carrier 2.

The discharge generated between the conductive pattern of the substrate 3a and the substrate 2c of the latent image carrier 2 is the absolute value of the voltage (predetermined voltage V ₀ ) between the substrate 3a and the latent image carrier 2. Is greater than the discharge starting voltage V _th , the gap between the substrate 3a and the latent image carrier 2 and the discharge starting voltage V _th
FIG. 4C shows the relationship with Paschen's law. That is, when the gap is about 30 μm, the discharge starting voltage V _th is the smallest, and the gap is about 30 μm.
Regardless of whether it is smaller or larger than m, the discharge starting voltage _Vth becomes large, and it becomes difficult for discharge to occur. This discharge also causes the surface of the latent image carrier 2 to be charged or neutralized. However, when the resistance R of the write electrode 3 is in this region,
The charging or discharging of the latent image carrier 2 due to charge injection is large, and the charging or discharging of the latent image carrier 2 due to discharge is small, and the charging or discharging of the latent image carrier 2 is dominated by charging or discharging by charge injection. ing. In the charging or discharging by the charge injection, the surface potential of the latent image carrier 2 is
The predetermined voltage V ₀ or the ground voltage V ₁ applied to the writing electrode 3b. In the case of charging by charge injection, the writing electrode 3b
Predetermined voltage V ₀ is the discharge starting voltage V _th of discharge between the substrate 2c of the writing electrode 3b and the image bearing member 2 is generated to be supplied to the
It is desirable to set the following.

In a region where the resistance R of the writing electrode 3b is larger, the charging or discharging of the latent image carrier 2 due to the charge injection is small, and the charging or discharging of the latent image carrier 2 due to the discharge is the charging or discharging due to the charge injection. The charge or charge of the latent image carrier 2 gradually becomes dominant in the charge or charge by discharge. That is, when the resistance R of the writing electrode 3b increases, the surface of the latent image carrier 2 is charged or eliminated mainly by discharging, and the latent image carrier 2 is hardly charged or eliminated by charge injection. In or removal of charge by the discharge, the surface potential of the latent image carrier 2 becomes a voltage obtained by subtracting the discharge starting voltage V _th from the predetermined voltage V ₀ or ground voltages V ₁ is applied to the writing electrode 3b. The same applies to the case where the predetermined voltage V ₀ is a voltage of (+).

Therefore, the resistance R of the electrode 3b is changed by the latent image
A predetermined voltage | V where the surface potential of the carrier 2 is constant₀｜ (±
Pressure, so it is expressed in absolute value) or constant ground voltage
V₁And the writing electrode 3
a predetermined voltage V ₀And ground voltage V₁Between
Latent image by charge injection by switching control
The support 2 can be charged or neutralized.
You.

Further, the write electrode 3b is connected to the A side to
A predetermined voltage V of (-) is applied to the write electrode 3b. ₀When applying
The relationship between the capacitance C of the latent image carrier 2 and the surface potential of the latent image carrier 2
The relation is as shown by the solid line in FIG.
In a region where C is small, the surface potential of the latent image carrier 2 is constant.
Constant voltage V₀And the capacitance C of the dielectric 2b is larger than a predetermined value.
In the threshold region, the absolute value of the surface potential of the latent image carrier 2 decreases.
I do. On the other hand, the write electrode 3b is connected to the B side to
The capacity C of the latent image carrier 2 when the pole 3b is grounded and the latent image carrier
The relationship with the surface potential of the holding body 2 is shown by a dotted line in FIG.
In the region where the capacity C of the latent image carrier 2 is small,
Substantially the ground voltage V where the surface potential of the body 2 is constant ₁And the latent image
In a region where the capacity C of the carrier 2 is larger than a predetermined value,
The absolute value of the surface potential of the holder 2 increases.

Then, in a region where the capacity C of the latent image carrier 2 is small and the surface potential of the latent image carrier 2 is a constant predetermined voltage V ₀ or a constant ground voltage V ₁ , the latent image carrier 2 contacts the latent image carrier 2. Charge injection of (-) charge is directly performed between the writing electrode 3b and the charged layer 2d of the latent image carrier 2. That is, the latent image carrier 2 is charged or eliminated by charge injection. Further, in a region where the capacitance C of the latent image carrier 2 is large and the surface potential of the latent image carrier 2 starts to change, the charge or static elimination of the latent image carrier 2 due to charge injection gradually decreases, and the latent image carrier 2 As the capacitance C of the body 2 is increased, FIG.
As shown in (b), discharge occurs between the substrate 3a and the latent image carrier 2. This discharge also causes the surface of the latent image carrier 2 to be charged or neutralized. However, when the capacity C of the latent image carrier is in this region, the charge or static elimination of the latent image carrier 2 due to charge injection is large, and the charge or static elimination of the latent image carrier 2 due to discharge is small. Charging or discharging is dominated by charging or discharging by charge injection. In the charging or discharging by the charge injection, the surface potential of the latent image carrier 2 is changed to the predetermined voltage V ₀ or the ground voltage V ₁ applied to the writing electrode 3b.
Becomes

In a region where the capacitance C of the latent image carrier 2 is even larger, this charge injection is hardly performed between the writing electrode 3b and the charged layer 2d of the latent image carrier 2. That is, the latent image carrier 2 is not charged or neutralized by charge injection. The same applies to the case where the predetermined voltage V ₀ is a voltage of (+).

Therefore, the capacitance C of the latent image carrier 2 is changed to a predetermined voltage | V ₀ | (the surface voltage of the latent image carrier 2 is represented by an absolute value because of ± voltage) or a constant ground voltage. and sets a small region to be a V _1, by switching control between the voltage applied to the writing electrode 3b and the predetermined voltage V ₀ and the ground voltage V _1, the latent image carrier 2 by charge injection or It is possible to perform static elimination.

Further, the write electrode 3b is connected to the A side to
A predetermined voltage V of (-) is applied to the write electrode 3b. ₀When applying
Speed (peripheral speed) v of latent image carrier 2 and surface of latent image carrier 2
The relationship between the latent image and the potential is shown by the solid line in FIG.
In a region where the speed v of the carrier 2 is relatively low, the latent image carrier 2
Surface potential increases as the velocity v increases,
When the speed v of the latent image carrier 2 becomes larger than a predetermined value, the latent image
The absolute value of the surface potential of the carrier 2 is a constant voltage. Latent image
The surface potential of the carrier 2 increases as the speed v of the latent image carrier 2 increases.
The difference between the writing electrode 3b and the latent image carrier 2
Simplification of charge injection into the latent image carrier 2 due to friction between
It is considered to be something. This frictional charge injection
This can be facilitated by increasing the speed v of the latent image carrier 2 to some extent.
It does not change and remains almost constant. On the other hand, the write electrode 3b is set to B
When the write electrode 3b is connected to the ground and the write electrode 3b is grounded.
The relationship between the velocity v of the dielectric 2b and the surface potential of the dielectric 2b is shown in FIG.
As shown by the dotted line in (e), there is no relation to the speed v of the dielectric 2b.
Constant ground voltage V₁Becomes The predetermined voltage V₀But
The same applies to the case of the voltage of (+).

Further, the write electrode 3b is connected to the A side to
A predetermined voltage V of (-) is applied to the write electrode 3b. ₀When applying
The pressing force of the writing electrode 3b against the latent image carrier 2 (hereinafter simply referred to as writing
And the surface potential of the latent image carrier 2
The relationship between the write electrode 3b and the write electrode 3b as shown by the solid line in FIG.
In the region where the pressure is extremely small, the surface of the latent image carrier 2
The potential increases as the pressure of the writing electrode 3b increases.
And the pressure of the writing electrode 3b becomes larger than a predetermined value.
Then, the absolute value of the surface potential of the latent image carrier 2 is a constant voltage.
Becomes The surface potential of the latent image carrier 2 is the pressure of the writing electrode 3b.
As the write electrode 3b and the latent image bear,
The contact with the holder 2 increases with the increase in the pressure of the writing electrode 3b.
It is thought that it is because it becomes more certain.
The certainty of the contact between the writing electrode 3b and the latent image carrier 2 is as follows.
It does not change when the pressure of the writing electrode 3b increases to some extent.
And almost constant. On the other hand, write electrode 3b is connected to B side
Of the write electrode 3b when the write electrode 3b is grounded.
The relationship between the pressure and the surface potential of the latent image carrier 2 is shown in FIG.
Is constant irrespective of the pressure of the writing electrode 3b as shown by the dotted line in FIG.
Ground voltage V₁Becomes The predetermined voltage V₀Is (+)
The same is true for pressure.

In this manner, the resistance R of the writing electrode 3b and the capacitance C of the latent image carrier 2 are set so that the surface potential of the latent image carrier 2 becomes a constant predetermined voltage, and the latent image carrier 2 is set. the pressure of the second velocity v and the writing electrode 3b is controlled so that the surface potential of the latent image carrier 2 is constant predetermined voltage, the voltage applied to the writing electrode 3b and the predetermined voltage V ₀ ground voltages V ₁
By performing switching control between these steps, charging or discharging of the latent image carrier 2 by charge injection can be performed reliably and easily.

Although the predetermined voltage V ₀ applied to the write electrode 3b is a DC voltage in the above-described example, an AC voltage can be superimposed on the DC voltage. When the AC voltage is superimposed, the DC component is set to a voltage applied to the latent image carrier 2, the amplitude of the AC component is set to be twice or more the discharge start voltage Vth, and the frequency of the AC component is set to the latent image carrier. Preferably, the frequency of the rotation of the body 2 is about 500 to 1000 times (for example, if the diameter of the latent image carrier 2 is 30φ and the peripheral speed of the latent image carrier 2 is 180 mm / sec, the latent image carrier 2 Since the frequency at the rotation of is 2 Hz,
The frequency of the AC component is 1000 to 2000 Hz).
By superimposing the AC voltage on the DC voltage in this way, the charging or static elimination by the discharge of the writing electrode 3b becomes more stable, and the writing voltage is vibrated by the AC voltage, so that the writing electrode 3b adheres to the writing electrode 3b. Foreign matter can be removed, and contamination of the writing electrode 3b can be prevented.

Next, the flexible substrate 3a that supports the writing electrode 3b of the writing device 3 will be described. FIG. 5 is a schematic view of the latent image carrier 2 as an example of the writing device 3 as viewed from the axial direction. As described above, the base material 3a is made of a flexible material having relatively soft elasticity such as FPC.
Writing electrodes 3 to the distal end portion 3a ₁ of the substrate 3a, as shown in
b is fixed. Then, a plurality of writing electrodes 3b are arranged in the axial direction (main scanning direction) of the latent image carrier 2 (FIG. 8).
The substrate 3a is formed in a rectangular plate shape having a length substantially equal to the axial length of the charged layer 2d of the latent image carrier 2 in the axial direction of the latent image carrier 2. Is formed. The end 3a ₂ of the writing electrode 3b of the substrate 3a and the opposite side is fixed by a suitable fixing member. The substrate 3a is provided so as to extend from the right side in FIG. 5 so as to oppose the rotation direction of the latent image carrier 2 (clockwise direction indicated by an arrow). The substrate 3a may be provided so as to extend in the same direction as the rotation direction of the latent image carrier 2 from the left in FIG.

In this state, the substrate 3a is slightly elastically bent to generate a weak elastic restoring force, and the writing electrode 3b is lightly pressed on the latent image carrier 2 with a small pressing force by the elastic restoring force. Pressed and in contact. Thus, the write electrode 3b
Is small, the wear of the charged layer 2d of the latent image carrier 2 by the writing electrode 3b is suppressed, and the durability is improved. Since the writing electrode 3b is in contact with the charged layer 2d by the elastic force, the writing electrode 3b comes into stable contact with the charged layer 2d. Incidentally, the end portion 3a ₂ of the substrate 3a, the driver 11 which controls the operation of the writing electrode 3b to be described later is fixed.

As shown in FIG. 5, when the substrate 3a is provided so as to oppose the rotation direction of the latent image carrier 2, foreign matters adhering to the latent image carrier 2 can be removed, and When the substrate 3a is provided in the same direction as the rotation direction of the latent image carrier 2, foreign matter adhering to the latent image carrier 2 is removed from the substrate 3a. Latent image carrier 2
You will be able to get through.

FIG. 6 is a schematic view of another example of the writing device 3 as seen from the axial direction of the latent image carrier 2. Although the above example is set simply to resiliently slightly flexed state by a rectangular plate-shaped base member 3a is fixed to its end 3a _2, the writing device 3 of this embodiment, As shown in FIG. 6, a rectangular plate-shaped substrate 3a made of the same material as the substrate 3a of the above-described example.
Is bent in a hairpin curve shape along a line in the axial direction of the latent image carrier 2 at a central portion in a direction orthogonal to the axial direction of the latent image carrier 2, and both ends 3 a ₁ and 3 a ₂ thereof are appropriately formed. Is fixed by the fixing member. In this case, a conductive mounting plate (shield) for preventing crosstalk between the two portions of the base material 3a bent up and down in the figure is provided between both end portions 3a ₁ and 3a ₂ of the base material 3a. ) 10 is interposed.

The length of the substrate 3a in this example in the axial direction of the latent image carrier 2 is set to be substantially the same as the length of the charged layer 2d of the latent image carrier 2 in the axial direction. a predetermined position of the hairpin-shaped portion (bent portion) 3a _3, the writing electrodes 3b are a plurality of rows fixed in the axial direction of the latent image carrier 2. Then, as shown in FIG.
a _1, 3a in a state _{where 2} is fixed, hairpin-shaped portions 3a ₃ of the substrate 3a are deflected slightly elastically, writing a weak elastic restoring force of hairpin-shaped portions 3a ₃ of the substrate 3a The electrode 3b is lightly pressed onto the latent image carrier 2 and is in contact therewith. In the writing device 3 of this example, since the base material 3a is supported by both ends 3a ₁ and 3a ₂ ,
The writing electrode 3b comes into contact more reliably and more stably.

FIG. 7 is a view similar to FIG. 5, showing another example of the image forming apparatus of the present invention. In each of the above-described examples, the writing electrode 3b is assumed to be in contact with the latent image carrier 2, but in the image forming apparatus 1 of this example, the writing electrode 3b generates a discharge with respect to the latent image carrier 2. In such a manner that they are separated by a predetermined gap (proximity distance). That is, FIG.
As shown in the figure, an insulating layer 28 is provided on the surface of the substrate 3a facing the latent image carrier 2. In this case, the insulating layer 28
Is formed such that the write electrode 3b at the electrode portion of the conductive pattern 9 is exposed from above the conductive pattern 9 formed on the base material 3a. The thickness of the insulating layer 28 is set to be larger than the thickness of the write electrode 3b by a predetermined thickness.

Then, the insulating layer 28 is lightly pressed onto the latent image carrier 2 with a weak elastic restoring force due to the bending of the substrate 3a and is in contact therewith. Since there is a difference in thickness between the insulating layer 28 and the writing electrode 3b, when the insulating layer 28 comes into contact with the latent image carrier 2, the writing electrode 3b (Proximity distance). The close distance is set to, for example, about 30 to 100 μm, and can be adjusted by the thickness of the insulating layer 28. The adjustment of the close distance can be performed in the process of forming the insulating layer 28, for example, in the process of applying the insulating photoresist to the base material 3a when the insulating layer 28 is formed of an insulating photoresist.

FIG. 8 is a diagram showing a switching circuit for switching and connecting predetermined voltage V ₀ and ground voltage V ₁ to write electrode 3b. As shown in FIG. 8, for example, the write electrodes 3b arranged in four rows are respectively connected to corresponding high voltage switches (High Voltage Switches; HVSW) 15, and these high voltage switches 15 ,
It is adapted to switch connection of the corresponding electrode 3b to the predetermined voltage V ₀ and the ground voltage V1. An image writing control signal from a shift register (SR) 16 is input to each of the high voltage switches 15.
, The image signal stored in the buffer 17 and the clock signal from the clock 18 are input.
Then, the image write control signal from the shift register 16 is input to each high voltage switch 15 by the AND circuit 19 based on the write timing signal from the encoder 20. Each high voltage switch 15 and AND circuit 1
The driver 9 for controlling the switching of the supply voltage to each write electrode 3b is constituted by 9.

FIG. 9 shows each high voltage switch 1 of each electrode 3b.
5 shows a state when switching control is selectively performed to a predetermined voltage V0 or a ground voltage V1, respectively. (A) is a diagram showing a voltage state of each electrode, and (b) is a normal development in the voltage state of (a). FIG. 7C is a diagram illustrating a developer image at the time, and FIG. 7C is a diagram illustrating a developer image when reversal development is performed in the voltage state of FIG. FIG.
As shown in FIG. 9, for example, each of the (n−2) -th, (n−1) -th, (n + 1) -th, and (n + 2) -th electrodes 3b is controlled by switching the respective high-voltage switches 15 to the voltage state shown in FIG. Let's say Then, while writing an electrostatic latent image on the latent image carrier 2 with each electrode in such a voltage state, and developing this electrostatic latent image by regular development,
The developer 8 adheres on a predetermined voltage V ₀ portion of the latent image carrier 2,
A developer image as shown by hatching (oblique lines) in FIG. 9B is obtained. Similarly, the electrostatic latent image is written,
When developing the electrostatic latent image by reversal development, the developer 8 is deposited on the ground voltages V ₁ part of the latent image carrier 2, FIG. 9 (c)
Thus, a developer image as shown by hatching is obtained.

According to the image forming apparatus 1 using the writing device 3 configured as described above, since the writing electrode 3b is supported by the flexible base material 3a, the latent image of the writing electrode 3b is formed. The position with respect to the carrier 2 can be set flexibly. Therefore, the position of the writing electrode 3b with respect to the latent image carrier 2 is stabilized, and charge injection between the writing electrode 3b and the latent image carrier 2 can be performed stably and reliably. As a result, the latent image carrier 2 can be more stably charged or neutralized by the writing electrode 3b with higher accuracy, and thus the electrostatic latent image can be more stably written. An image can be obtained reliably and with high accuracy.

Also, since the writing electrode 3b can be brought into contact with the latent image carrier 2 with a small pressing force or can be made surely close to the latent image carrier 2 by the flexible base material 3a, The spatial gap between the input electrode 3b and the latent image carrier 2 can be made extremely small. This can reduce the chance of unnecessary ionization of the air in the spatial gap, so that the generation of ozone can be further suppressed and an electrostatic latent image can be formed at a low potential.

Further, since the writing electrode 3b is only brought into contact with the latent image carrier 2 with a small pressing force, the writing electrode 3b
b can prevent the latent image carrier 2 from being damaged.
Can be improved in durability. Further, the writing device 3
Only the writing electrode 3b is used, and a large-sized laser light generator, LED lamp light generator, and the like are not provided as in the related art, so that the apparatus can be further downsized and the number of parts can be reduced. It is possible to obtain a simpler and less expensive image forming apparatus that can be further reduced.

Further, by bringing the insulating layer 28 provided on the base material 3a into contact with the latent image carrier 2, the writing electrode 3b is stably brought close to the two latent image carriers with a predetermined gap. Can be done. Therefore, writing of the electrostatic latent image by the writing electrode 3b can be performed stably and with high accuracy. Furthermore, since the writing electrode 3b is merely located close to the latent image carrier 2, the damage of the latent image carrier 2 by the writing electrode 3b is prevented, and the durability of the latent image carrier 2 is improved. Further, even if the insulating layer 28 is in contact with the latent image carrier 2, since the insulating layer 28 is provided on the flexible base material 3 a, the pressing force of the insulating layer 28 pressing the latent image carrier 2 Can be set very lightly, and damage to the latent image carrier by the flexible insulating layer can be suppressed.

Next, a specific example of an image forming apparatus using the writing device of the present invention for writing an electrostatic latent image by bringing the electrode 3b into contact with the latent image carrier 2 will be described. FIG. 10 schematically shows an example of an image forming apparatus using the writing device of the present invention, wherein (a)
FIG. 2 is a diagram illustrating an image forming apparatus having a cleaner, and FIG. 2B is a diagram illustrating a cleanerless image forming apparatus having no cleaner. The image forming apparatus 1 shown in FIG. 10A is a monochrome image forming apparatus, and a base material 3a of the writing device 3 extends from the upstream side to the downstream side in the rotation direction of the latent image carrier 2, and Write electrode 3b fixed to the tip of base material 3a
Is provided. Further, the latent image carrier 2 is transferred from the transfer device 6.
The cleaning device 21 is provided on the downstream side in the rotation direction of the cleaning device 21. Although not shown, between the writing device 3 and the cleaning device 21, the above-described latent image carrier uniform charge control device 7 is provided.
May be provided. If the latent image carrier uniform charge control device 7 is not provided, a latent image is formed by overwriting the previous latent image. It is possible to reduce the number of points and downsize the device.

In the monochrome image forming apparatus 1 configured as described above, after the surface of the latent image carrier 2 is uniformly charged by the latent image carrier uniform charge controller 7 in the same manner as described above, The electrostatic latent image is written on the surface of the latent image carrier 2 by each of the writing electrodes 3b of the writing device 3 charging or discharging the latent image carrier 2. The latent image on the latent image carrier 2 is developed after the developer is adhered to the latent image carrier 2 by a developing roller 4a of a developing device 4 that is not in contact with the latent image carrier 2 and then developed. Is transferred to the transfer material 5 by the transfer device 6. The developer remaining on the latent image carrier 2 after the transfer is removed by the cleaning blade 21a of the cleaning device 21, and the surface of the cleaned latent image carrier 2 is made uniform again by the latent image carrier uniform charge control device 7. Charged state. The image forming apparatus 1 of this example is a writing apparatus 3 of the present invention.
, A smaller and simpler configuration can be achieved.

The image forming apparatus 1 shown in FIG. 10B is a cleanerless image forming apparatus which does not include the cleaning device 21 in the image forming apparatus 1 shown in FIG. In the image forming apparatus 1 of this example, the developing roller 4a of the developing device 4 is in contact with the latent image carrier 2, and performs contact development.

In the image forming apparatus 1 of this embodiment thus configured, the latent image carrier 2 and the latent image carrier 2 after the previous transfer are placed on the latent image carrier 2 by the unillustrated latent image carrier uniform charge control device 7. After the remaining residual developer is brought into a uniform charge state, the surface of the latent image carrier 2 and the surface of the residual developer are charged or eliminated by the writing electrode 3b of the writing device 3, and the latent image carrier 2 is charged. An electrostatic latent image is written on the top and on the residual developer. Then, these electrostatic latent images are developed by the developing device 4. At this time, by selecting the charging line of the writing electrode 3b to be charged to the polarity that the developer 8 originally has, the residual developer in the non-image portion on the latent image carrier 2 is removed by the writing electrode 3b. Since it is charged to that polarity, it moves toward the developing device 4, and the residual developer in the image area on the latent image carrier 2 remains on the latent image carrier 2 and is used as a developer image. Become. By moving the residual developer in the non-image area toward the developing device 4 in this manner, the surface of the latent image carrier 2 can be cleaned without providing the cleaning device 21. In particular, although not shown, a brush is provided downstream of the transfer device 6 in the rotation direction of the latent image carrier 2, and the residual developer on the latent image carrier 2 is scattered and leveled by the brush, so that a non-image portion is formed. Some residual developer can be more effectively moved to the developing device 4 and removed.

The other image forming operations of the image forming apparatus 1 of this example are the same as those of the image forming apparatus 1 shown in FIG. The image forming apparatus 1 of this example can also have a smaller and simpler configuration by using the writing device 3 of the present invention. Configuration.

FIG. 11 is a diagram schematically showing another example of an image forming apparatus using the writing device of the present invention. As shown in FIG. 11, an image forming apparatus 1 of this example performs full-color development by superimposing four colors of black K, yellow Y, magenta M, and cyan C on a latent image carrier 2. And a latent image carrier 2 in the form of an endless belt. The endless belt-shaped latent image carrier 2 is stretched between two rollers 22 and 23, and is rotated clockwise in the drawing by a driving roller among the rollers 22 and 23.

Along the linear portion of the endless belt of the latent image carrier 2
And a writing device 3 for each color._K, 3_Y, 3_M, 3_Cand
Developing device 4_K, 4_Y, 4_M, 4_CIs in the rotational direction of the latent image carrier 2.
The colors K, Y, M, and C are arranged in this order from the upstream side. Mochi
Of course, these developing devices 4_K, 4 _Y, 4_M, 4_CIs other than shown
They can be arranged in any order. Writing equipment for each color
Place 3_K, 3_Y, 3_M, 3_CEach writing electrode 3b_K, 3b_Y, 3b_M, 3
b_CIs a flexible substrate 3a as described above._K, 3
a_Y, 3a_M, 3a_CIt is provided in. Not shown
However, in the image forming apparatus 1 of this example, the latent image carrier 2
Endless belt writing device 3_K, 3_Y, 3_M, 3_CAnd the other side
The above-described latent image carrier uniform charge control device 7 is provided at the line portion.
ing.

[0070] In the image forming apparatus 1 of this embodiment configured in this way, an electrostatic latent image of black K is written on the surface of the latent image carrier first with electrodes 3b _K of the writing device 3 _K for black K At the same time, the electrostatic latent image of black K is developed by the developing device _4K , and the black
Is formed. Next, the electrostatic latent image of cyan C is applied to the latent image carrier 2 _{C by} the electrode 3b _C of the writing device 3 _C for cyan _C.
With written superimposed on and on the developer image of black K surfaces of cyan C developer image on an electrostatic latent image of the cyan C is developed in the surface of the latent image bearing member 2 by the developing device 4 _C Is formed. Similarly, after the electrostatic latent image of magenta M is written on top of each developer image of the latent image bearing member 2 and the black K and cyan C by electrodes 3b _M of the writing device 3 _M of magenta M , an electrostatic latent image of magenta M is the magenta developer image M is formed on each developer image on the surface of being developed by the developing device 4 _M latent image carrier 2 and black K and cyan C, further, Electrode 3b _C of writing device 3 _C for cyan _C
After the electrostatic latent image of cyan C is written on the latent image carrier 2 and the developer images of black K, cyan C, and magenta M, the electrostatic latent image of cyan C is developed by the developing device 4 _C
To form a cyan C developer image on the surface of the latent image carrier 2 and on each of the black K, cyan C and magenta M developer images, and color-matching. Then, these developer images are transferred. A full-color developer image in which the developer images of the respective colors are color-matched on the transfer material 5 by the device 6 is formed. The order of forming the developers of each color can be set to any order other than the order described above. As described above, even in a full-color image forming apparatus in which the developer images of the respective colors are superimposed on the latent image carrier 2 and color-matched, the use of the writing device 3 of the present invention makes the image forming apparatus smaller and simpler. Configuration.

FIG. 12 is a diagram schematically showing still another example of the image forming apparatus using the writing device of the present invention. FIG.
As shown in FIG. 1, in the image forming apparatus 1 of this example, the image forming apparatuses 1 _K , 1 _C , 1 _M , and 1 _Y for each color are tandemly arranged in this order from the upstream side in the moving direction of the transfer material 5. ing. The arrangement order of the image forming apparatuses 1 _K , 1 _C , 1 _M , and 1 _Y for each color can be set in any order. Each image forming apparatus 1 _K ,
1 _C , 1 _M , and 1 _Y are latent image carriers 2 _K , 2 _C , 2 _M ,
2 _Y , writing devices 3 _K , 3 _C , 3 _M , 3 _Y , developing devices 4 _K , 4 _C , 4 _M ,
4 _Y , and transfer devices 6 _K , 6 _C , 6 _M , 6 _Y. Although not shown, each of the image forming apparatuses _1K , _1C , _1M , and _1Y
Each of the same latent image carrier uniform charge control devices 7 as described above.
There writer 3 _K for each color, 3 _C, 3 _M, 3 each from _Y latent image carrier _{2 K, 2 C, 2 M} , 2 Y may be disposed in the upstream side in the rotation direction of the.

The image forming apparatus of this embodiment thus configured
In the apparatus 1, first, a black K image forming apparatus 1_KTo
The black K latent image carrier uniform charge control device 7
Therefore, the latent image carrier 2_KAfter the surface of the
Loading device 3_KElectrode 3b_KThe latent image of black K
Holding body 2_KThe surface of this black is written
K electrostatic latent image is developed by developing device 4_KImage carrier 2 developed with_K
A black K developer image is formed on the surface. This latent image
Carrier 2_KThe upper black K developer image is transferred to the transfer device 6_Kso,
The image is transferred to the supplied transfer material 5 and
A developer image of K is formed. Next, an image of cyan C
Forming device 1_C, The uniform charge of the cyan C latent image carrier
The latent image carrier 2 is controlled by the controller 7._CSurface is uniformly charged
After that, the writing device 3_CElectrode 3b_CAnd the electrostatic latent of cyan C
The image is a latent image carrier 2_COn the surface of the
Developing device 4_CLatent image developed in
Carrier 2_CA cyan C developer image is formed on the surface of the substrate.
This latent image carrier 2_CTransfer device for cyan C developer image
6_CAs a result, the supplied black K developer image is formed.
Is transferred onto the transferred transfer material 5, and the cyan C
A developer image is formed. Similarly, the image of magenta M
Forming device 1_MWriting device 3_MElectrode 3b _MSubmersible by
Image carrier 2_MWriting and developing device for magenta M electrostatic latent image
Place 4_MFor developing and transferring an electrostatic latent image of_MTransfer material 5
After the superimposition transfer of the magenta M developer image to
Yellow Y image forming apparatus 1_YWriting device 3_YNo electricity
Pole 3b _YLatent image carrier 2_YYellow Y electrostatic latent image
Writing and developing device 4_YFor developing and transferring electrostatic latent images
Place 6_YTransfer of the yellow Y developer image to the transfer material 5
Then, the transfer material 5 is color-matched with the developer image of each color.
A full-color developer image is formed. Thus, each color image
Image forming apparatus 1_K, 1_C, 1_M, 1_YIs located in tandem
The writing apparatus of the present invention is also applicable to a multicolor image forming apparatus.
3 makes it more compact and simpler
Can be

FIG. 13 shows an image using the writing apparatus of the present invention.
It is a figure which shows the further another example of a forming apparatus typically. FIG.
Image forming apparatus 1 of each color shown in FIG._K, 1_C, 1_M, 1_YBut tongue
In the image forming apparatus 1 arranged in dem, each image forming apparatus
1_K, 1_C, 1_M, 1_YLatent image carrier 2_K, 2_C, 2_M, 2_YFormed into
The developer images of the respective colors are transferred to the respective image forming apparatuses 1._K, 1_C, 1_M, 1_Y
Is transferred to the transfer material 5 every time.
In the image forming apparatus 1 shown in FIG.
Carrier 2_K, 2_C, 2_M, 2_YThe developer image of each color formed on
Once the intermediate transfer is performed, the image is transferred to the transfer material 5.
ing. That is, in the image forming apparatus 1 of this example,
An intermediate transfer device 24 is provided in the image forming apparatus 1 of the example shown in FIG.
Have been killed. The intermediate transfer device 24 has an endless belt shape.
An intermediate transfer member 25 is provided.
Is stretched between two rollers 26 and 27.
Drive to rotate counterclockwise in the figure.
ing. Then, along the linear portion of the intermediate transfer body 25,
Each image forming apparatus 1_K, 1_C, 1 _M, 1_YIs arranged
At the same time, one transfer device 6 is provided at the position of the roller 27.
Have been. Another configuration of the image forming apparatus 1 of this example is shown in FIG.
2 is the same as the image forming apparatus 1 of the example shown in FIG.

In the image forming apparatus 1 of this embodiment configured as described above, the latent image carriers 2 _K , 2 _C , 2 _M , and 2 _Y of the respective colors are provided similarly to the image forming apparatus 1 of the example shown in FIG. The developer images of the respective colors are formed, and the developer images of the respective colors are color-matched in the same manner as when the developer images of the respective colors are transferred to the transfer material 5 in the example shown in FIG. Is over-transferred. The developer image of each color intermediately transferred to the intermediate transfer body 25 is transferred to the transfer material 5 by the transfer device 6, and a full-color developer image is formed on the transfer material 5. Other image forming operations of the image forming apparatus 1 of this example are the same as those of the image forming apparatus 1 of the example shown in FIG. Thus, the intermediate transfer device 24
And a full-color image forming apparatus in which the image forming apparatuses 1 _K , 1 _C , 1 _M , and 1 _{Y of} each color are arranged in tandem.
By using the writing device 3 of the present invention, it is possible to make the configuration smaller and simpler.

FIG. 14 is a view similar to FIG. 5, schematically and partially showing still another example of the embodiment of the image forming apparatus according to the present invention. In each of the above examples, the latent image carrier uniform charge control device 7 for uniformly charging the latent image carrier 2 is provided independently of the writing device 3. In the image forming apparatus 1 of the first embodiment, as shown in FIG.
Are provided integrally with the writing electrode 3b. That is,
The distal end portion 3a ₁ of the substrate 3a of the writing device 3, together with the uniform charge control electrode 7e of the image bearing member uniformly charge control device 7 is provided, the uniform charge control electrode 7e with a predetermined gap And the write electrode 3b is provided. In this case, the uniform charge control electrode 7e is formed in a thin plate shape having a rectangular cross section, and is continuous in the axial direction of the latent image carrier 2 by the same length as the axial length of the charged layer 2d of the latent image carrier 2. It has been extended. Each of the writing electrode 3b and the uniform charge control electrode 7 is in contact with the surface of the latent image carrier 2 with a small pressing force by a weak elastic restoring force due to the bending of the substrate 3a.

[0076] After the image forming apparatus 1 of this embodiment configured in this manner, the latent image bearing member 2 of the surface in a uniform charge control electrode 7e of the distal end portion 3a ₁ of the substrate 3a is uniformly charged,
The electrostatic latent image is written on the surface of the latent image carrier 2 by the writing electrode 3b charging or discharging the latent image carrier. In the image forming apparatus 1 of this example, since the uniform charge control electrode 7e and the writing electrode 3b are provided integrally, the image forming apparatus 1 can be formed more compact and simpler. Other configurations and other operational effects of the image forming apparatus 1 of this example are the same as those of the example shown in FIG.

As a writing member, other writing members capable of writing an electrostatic latent image can be used in addition to the writing electrode 3b as in the above-described example. Further, the provision of the uniform charge control electrode 7e and the writing electrode 3b integrally is not limited to the example shown in FIG. 14, but may be applied to the writing device 3 in which the writing electrode 3b is brought close as shown in FIG. In this case, as in the case of the write electrode 3b, the uniform charge control electrode 7
e may be brought into contact with the electrostatic latent image carrier 7 or may be brought close to the electrostatic latent image carrier 7. Further, it is needless to say that the provision of the uniform charge control electrode 7e and the writing electrode 3b integrally can be applied to the image forming apparatus of the other example described above, and the same operation and effect can be obtained. No. Further, an appropriate insulator can be provided in a gap between the writing electrode 3b and the uniform charge control electrode 7e.

[0078]

As is apparent from the above description, according to the image forming apparatus of the present invention, since the writing member is supported by the flexible base material, the writing member is capable of supporting the latent image carrier. The position can be set flexibly. Therefore, the writing of the electrostatic latent image on the latent image carrier by the writing member can be performed more stably, so that a good image can be obtained reliably and with high accuracy.

Further, the writing electrode can be brought into contact with the latent image carrier with a small pressing force by the flexible base material, or the writing electrode can be reliably brought closer to the latent image carrier. The spatial gap with the image carrier can be made very small. This can reduce the chance of unnecessary ionization of the air in the spatial gap, so that the generation of ozone can be further suppressed and an electrostatic latent image can be formed at a low potential.

In particular, according to the third aspect of the present invention, since only the writing electrode is used as the writing member, the conventional large-sized laser light generator, LED lamp light generator, and the like are not required. it can. Therefore, the size of the apparatus can be further reduced, and the number of parts can be further reduced, so that a simpler and less expensive image forming apparatus can be obtained. According to the third aspect of the present invention, since the writing member is only brought into contact with the latent image carrier with a small pressing force, the latent image carrier can be prevented from being damaged by the writing electrode, and the latent image carrier can be prevented. Improves body durability.

Further, according to the fourth aspect of the present invention, since the insulating layer provided on the base material is in contact with the latent image carrier, the writing member has a predetermined gap with respect to the latent image carrier. And can be stably approached. Therefore, the writing of the electrostatic latent image by the writing member can be performed stably and with high accuracy. Further, since the writing member is merely located close to the latent image carrier, damage to the latent image carrier by the writing member can be prevented, and the durability of the latent image carrier can be improved. Further, even when the insulating layer is brought into contact with the latent image carrier, since the insulating layer is provided on the flexible base material, the pressing force for pressing the insulating layer against the latent image carrier can be set extremely small, Damage to the latent image carrier by the flexible insulating layer can be suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a basic configuration of an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a diagram showing a basic process of image formation in the image forming apparatus of the present invention.

3A and 3B illustrate a principle of writing an electrostatic latent image by charging or discharging a writing electrode of a writing device, and FIG. 3A is an enlarged view of a contact portion between the writing electrode and a latent image carrier; FIG. 3B is an electrical equivalent circuit diagram of the contact portion, and FIGS. 3C through 3F are diagrams showing the relationship between each parameter and the surface potential of the latent image carrier.

4A and 4B are diagrams illustrating charging or discharging of a latent image carrier; FIG. 4A is a diagram illustrating charging or discharging of a latent image carrier by charge injection; FIG. 4B is a diagram illustrating charging or discharging of a latent image carrier by discharging; FIG. 3C is a diagram for explaining Paschen's law.

FIG. 5 is a schematic view of a latent image carrier of an example of a writing device as viewed from an axial direction.

FIG. 6 is a schematic view of a latent image carrier of another example of the writing device as viewed from an axial direction.

FIG. 7 shows another example of the image forming apparatus of the present invention.
FIG.

FIG. 8 is a diagram showing a switching circuit for selectively connecting a predetermined voltage V ₀ and a ground voltage V ₁ to a write electrode.

FIG. 9 shows a state when each high-voltage switch of each electrode is selectively switched to a predetermined voltage V0 or a ground voltage V1, and FIG. 9A is a diagram showing a voltage state of each electrode;
FIG. 6B is a diagram illustrating a developer image when normal development is performed in the voltage state of FIG. 7A, and FIG. 7C is a diagram illustrating a developer image when reverse development is performed in the voltage state of FIG.

10A and 10B schematically show an example of an image forming apparatus using the writing device of the present invention, in which FIG. 10A shows an image forming apparatus provided with a cleaner, and FIG. 10B shows a cleaner-less apparatus having no cleaner. 1 is a diagram illustrating an image forming apparatus of FIG.

FIG. 11 is a diagram schematically showing another example of the image forming apparatus using the writing device of the present invention.

FIG. 12 is a diagram schematically showing still another example of the image forming apparatus using the writing device of the present invention.

FIG. 13 is a view schematically showing still another example of the image forming apparatus using the writing device of the present invention.

FIG. 14 is a diagram similar to FIG. 5, schematically and partially showing still another example of the embodiment of the image forming apparatus according to the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 image forming apparatus 2 latent image carrier 3 writing apparatus 3
a: base material, 3b: writing electrode, 4: developing device, 5: transfer material, 6: transfer device, 7: latent image carrier uniform charge control device,
8: developer, 28: insulating layer

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kaneo Yoda 3-3-5 Yamato, Suwa City, Nagano Prefecture Seiko-Epson Corporation (72) Inventor Nobumasa Abe 3-5-5 Yamato, Suwa City, Nagano Prefecture Seiko -Epson Corporation (72) Inventor Yujiro Nomura 3-3-5 Yamato, Suwa City, Nagano Prefecture Seiko-Epson Corporation F Term (Reference) 2C162 AE12 AE21 AE31 AE37 AE44 AE47 EA17 2H029 AA06 AB04 AB07 AC01 AD06 AD07 2H030 AA06 AB02 AC02 AD02 BB42

Claims (7)

[Claims] A latent image carrier on which an electrostatic latent image is formed; a writing device for writing the electrostatic latent image on the latent image carrier; An image forming apparatus comprising at least a developing device for developing, wherein the developing device develops the electrostatic latent image written on the latent image carrier by the writing device to form an image; An image forming apparatus comprising: a writing member for writing the electrostatic latent image on the latent image carrier; and a flexible base material for supporting the writing member. 2. The image forming apparatus according to claim 1, wherein said writing member comprises a writing electrode. 3. The image forming apparatus according to claim 1, wherein the writing member is in contact with the latent image carrier with a small pressing force by the elastic force of the base. 4. The writing member, wherein the base member has an insulating layer, and the writing member is configured such that the insulating layer is brought into contact with the latent image carrier with a small pressing force by an elastic force of the base member. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is close to the latent image carrier. 5. The writing device and the developing device,
Black, yellow, magenta, and cyan are provided for each color, and the developer images of the respective colors are formed by being superimposed on the latent image carrier by the writing device and the developing device of the respective colors. The image forming apparatus according to claim 1, wherein: 6. The image forming apparatus for each of the colors, black, yellow, magenta, and cyan, provided with the latent image carrier, the writing device, and the developing device in tandem. The image forming apparatus according to claim 1, wherein: 7. The image forming apparatus according to claim 6, further comprising an intermediate transfer device for intermediately transferring a developer image for each color by the image forming device for each color.