JP2002311683A - Electrifying device and image forming device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrifying device in which electrification unevenness is reduced and is stabilized over a long term even in the case of electrifying a body to be electrified having a large width in the electrifying device using an electron emission element. SOLUTION: Gas including electric negative gas is brought into contact with at least a part of the electron emission element, and the body to be electrified is electrified with electron emitted and negative ion generated by the molecular of the electric negative gas, and the electron emission element 1 is divided into several divided electron emitting parts 31, 32, 33 and 34, and is split with each other by insulated parts 51, 52, 53 and 54, and also the divided electron emitting parts 31, 32, 33 and 34 are arranged in a direction A in parallel with the width direction of the body to be electrified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device for charging an object to be charged, and more particularly to an electron emission type charging device and a charging device for charging a photosensitive member using negative ions and electrons generated by electron emission. The present invention relates to an electrophotographic image forming apparatus using the apparatus.

[0002]

2. Description of the Related Art Conventionally, a charger used in an electrophotographic image forming apparatus basically generates ions by using discharge, and thus generates ozone and NOx. Although there is a contact type charger which is relatively less adversely affected by discharge, problems such as abrasion of the photoreceptor and adhesion of a NOx compound to the surface occur. Further, there is a problem in that a substance resulting from NOx generated by discharge adheres to the photoreceptor and absorbs moisture, thereby lowering the surface potential of the photoreceptor and generating a defective image.

In order to solve these problems, recently, a non-discharge type charge generator has been studied. For example,
There is known a charge generator used in an electrostatic latent image forming apparatus as disclosed in Japanese Patent Application Laid-Open No. 8-203418. In the electrostatic latent image forming apparatus described in this publication, a charge generator in which a PN junction semiconductor element or an electron emitting element layer made of an electroluminescent material is provided on the surface of a line electrode, and this is independently driven in units of one pixel A latent image is formed on the dielectric.

[0004]

However, the charge generator described in Japanese Patent Application Laid-Open No. 8-203418 is basically manufactured integrally with an electron-emitting device layer, so that a large-sized electron-emitting device can be manufactured. Requires a large device,
There remains a problem that manufacturing costs are high. Further, simply arranging the charge generator in the image forming apparatus has a problem that uneven charging tends to occur when a dielectric having a large width is charged.

[0005] With the recent increase in environmental protection awareness,
Standards for regulating the amount of ozone generated are also set for electrophotographic image forming apparatuses, and copiers and printers that do not exceed the regulated value by reducing the amount of ozone generated in the electrophotographic process Development is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and in a charging device using an electron-emitting device, even when a charged object having a large width is charged, the charging unevenness is small.
An object of the present invention is to provide a charging device capable of maintaining stable charging efficiency for a long period of time.

[0007] Further, the present invention has a low ozone generation amount,
It is an object of the present invention to provide an electrophotographic image forming apparatus capable of forming a high-quality image stably without reducing the life of a photoconductor due to NOx.

[0008]

According to a first aspect of the present invention, there is provided an electron emitting device which emits electrons which are energized by an internal electric field.
In a charging device for charging a charged object having a predetermined width by the electrons emitted from the electron-emitting device, a gas containing an electrically negative gas is brought into contact with at least a part of the electron-emitting device, and the emitted electrons are emitted. And a negative ion generated by the molecule of the electrically negative gas, the charged object is charged, and the electron-emitting device is divided into a plurality of divided electron-emitting portions, and the plurality of divided electron-emitting portions are charged. It is characterized by being arranged in a direction parallel to the width direction of the body.

The invention according to claim 2 is characterized in that independent electric conditions are set for each of the divided electron-emitting portions of the electron-emitting device.

[0010] The invention described in claim 3 is characterized in that it has a control means for controlling the amount of emission current by controlling the voltage applied to the electron-emitting device.

According to a fourth aspect of the present invention, the object to be charged is constituted by a photoreceptor, a detecting means for detecting a charging potential or a toner density of the photoreceptor, and a detection result based on the detection result of the detecting means. A feedback control mechanism for determining a voltage applied to the electron-emitting device.

The invention according to claim 5 is characterized in that the width of the electrode end portion in each divided electron emission portion of the electron emission element is changed.

According to a sixth aspect of the present invention, there is provided an arrangement in which a minute gap is provided in an electrode portion of each divided electron emission section in a direction perpendicular to the traveling direction of the member to be charged, and a portion close to the gap is provided. Is characterized in that the electrode width is larger than the electrode width of the other parts.

According to a seventh aspect of the present invention, the plurality of divided emission portions of the electron-emitting device are arranged in two rows along the traveling direction of the member to be charged, and the electrode portions of the divided electron emission portions in each row are arranged in two rows. It is characterized in that the electrode width of a portion adjacent to each other is smaller than the electrode width of another portion.

According to an eighth aspect of the present invention, in the electron-emitting device, portions other than the electrode portions of each of the divided electron-emitting portions are provided.
It is characterized by being covered with an insulator.

According to a ninth aspect of the present invention, in the charging device according to the eighth aspect, the insulator is made of an insulating resin.

According to a tenth aspect of the present invention, there is provided an image forming apparatus for forming an image by holding an electrostatic latent image on a photoreceptor, wherein the photoreceptor is formed by using the charging device according to the first to ninth aspects. It is characterized by being charged.

[0018]

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 shows a basic configuration example of an electron-emitting device of the charging device according to the present invention. FIG. 1 shows such a plane for convenience.

As shown in FIG. 1, the electron-emitting device 1 applied to the charging device of the present invention has a semiconductor layer 4 (for example, single-crystal silicon) formed on a substrate electrode 5 formed on a quartz substrate 6. Formed, the semiconductor layer 4 is made porous by anodic oxidation, and then is subjected to rapid thermal oxidation (RTO: Rapid Th).
The porous semiconductor layer (porous silicon) 2 is formed by thermal oxidation. The porous semiconductor layer 2 is covered with a thin oxide film, and finally, a thin film electrode 7 on the surface of which electrons can pass by a tunnel effect is formed.

The member to be charged shown in FIG. 1 is usually an electrophotographic photosensitive member. The illustrated electrode of the member to be charged can be considered as an aluminum drum of the photosensitive member. In this case, it is assumed that the member to be charged moves at a constant linear velocity S with respect to the electron-emitting device 1.

When a voltage of about 20 V is applied by the power supply 8, a current of about 1 mA / cm ² is observed as electrons in a vacuum. In the configuration shown in FIG. 1, since the gas is atmospheric pressure, the current value becomes lower due to ionization efficiency and the like. However, it is possible to charge with these ions like the scorotron charger for negative charging.

The electron-emitting device 1 shown in FIG. 1 uses a porous semiconductor layer (porous silicon) made of polysilicon. The method for producing the porous silicon is known, and is used in, for example, a field emission electron source disclosed in Japanese Patent No. 2966842 or the like. However, the electron-emitting device of the present invention is not limited to this, but may be any device that emits electrons from a solid as in the example shown in FIG.
It is applicable if the charging efficiency changes.

For example, MIS (metal-insulator-semiconductor) can be used as an electron-emitting device applicable to the charging device of the present invention.
It may have a structure or a MIM (metal-insulator-metal) structure.

(A) a semiconductor substrate; (b) a porous semiconductor layer whose surface is made porous by anodizing; and (c) a metal thin film formed on the porous semiconductor eyebrow. It may have an electrode and (d) an ohmic electrode formed on the back surface of the semiconductor substrate.

Further, a lower electrode and a lower electrode are formed on the lower electrode.
Tantalum oxide (Ta₂O ₅) Membrane and said tanta
Luoxide (Ta₂O₅) ZnS film formed on the film
And an upper electrode formed on the ZnS film.
That are used electroluminescent elements, etc.
It may be.

In the charging mechanism for ionization by the electron-emitting device of the present invention, the amount of ozone and NOx generated is extremely small.
However, in a process using a semiconductor, single-crystal silicon is about 300 mm, and large-sized polysilicon or amorphous silicon is limited by a film forming apparatus. In addition, the degree of variation increases as the size increases. In this configuration, for example, a large number of chips are manufactured by a 6-inch single crystal process, and classification is performed based on characteristics, thereby reducing charging unevenness.

FIG. 2 is a diagram for explaining negative ionization of an electrically negative gas by electron emission of the charging device of the present invention.

The composition of the negative ions of the electrically negative gas due to electron emission varies depending on atmospheric conditions, and is not necessarily fixed to this. However, the electric charge is transmitted generally in the form shown in FIG. It is thought to go.

The mean free path of electrons in the atmosphere is 0.3
It is said to be about 4 μm, and it is considered that charge transport by electrons is not dominant as long as it is in the atmosphere. The charging mechanism for ionization by these electron-emitting devices includes ozone, N
The generation amount of Ox is extremely small. However, since the amount of emitted electrons directly affects the charge amount, this unevenness directly affects the charge potential. A configuration to prevent this is required.

FIG. 3 shows a configuration example for explaining the first embodiment of the present invention.

As shown in FIG. 3, the electron-emitting device 1 of this embodiment has a plurality of divided electron-emitting portions 31, 32, 33, and 34.
(Only the electrode portions are shown), and are separated from each other by insulating portions 51, 52, 53 and 54. These split electron emission portions 31, 32, 33, 34
Are arranged in the direction parallel to the width direction of the member to be charged (for example, the direction perpendicular to the paper surface of FIG. 7) (the direction of dashed line A in FIG. 3).

As in the configuration of FIG. 1, the power supply voltage supplied from the power supply 8 is applied between the substrate electrode 5 of the electron-emitting device 1 and each of the electrode portions of the divided electron-emitting portions 31, 32, 33, and 34. However, the connection between the power supply 8 and each electrode portion is
1, 62, 63 and 64. Therefore, an independent electrical condition is set for each split electron emission section.

In the configuration example of FIG. 3, the variable resistor 61,
The potentials of the thin-film electrodes (extraction electrodes) 7 of the respective divided electron emission portions can be independently changed by 62, 63, and 64. This makes it possible to adjust the variation between the chips.

Further, the variable resistors 61, 62, 63, 64
Control signals C1, C2,
A control unit 42 for outputting C3 and C4 is provided. Therefore, the amount of emission current can be controlled by controlling the voltage applied to each divided electron emission portion of the electron emission element 1.

Further, in the configuration example shown in FIG. 3, a detecting section 41 for detecting a charging potential of the photosensitive member of the charged member (photosensitive member) 12 or a charge-causing factor such as toner density is provided. Alternatively, a detection signal indicating a detection result such as a toner concentration is supplied from the detection unit 41 to the control unit 42, and
The control unit 42 is configured as a feedback control mechanism that determines a voltage applied to the electron-emitting device 1 based on a detection result of the detection unit 41. By feeding back information from the charging sensor and the toner density sensor as the detection unit 41, a detection unit with less temporal unevenness can be formed.

FIG. 4 shows a configuration example for explaining a second embodiment of the present invention. FIG. 5 shows a configuration example for explaining a modification of the electron-emitting device of the charging device shown in FIG.

FIGS. 4 and 5 show only the chip structure of the electron-emitting device 1.

In the configuration example shown in FIG.
Are divided into a plurality of divided electron-emitting portions 30A, and the width of the electrode end portion in each divided electron-emitting portion 30A is changed. More specifically, in the direction perpendicular to the advancing direction (the direction of the dashed-dotted line T in FIG. 4) of the charged body (the direction of the dashed-dotted line A in FIG. 4), the minute electron The arrangement is such that a gap is provided, and the width of the electrode in the portion adjacent to the gap is larger than the width of the electrodes in the other portions.

In the case of horizontal arrangement as shown in FIG. 4, a gap is inevitably formed in a direction perpendicular to the moving direction of the member to be charged, and the amount of spatial current is reduced. However, this is prevented by increasing the electrode area in this portion.

In the modified example shown in FIG.
Are arranged in two rows along the advancing direction of the member to be charged (the direction of the dashed-dotted line T in FIG. 5), and the electrode portions of the divided electron emission sections 30B in each row are close to each other. The electrode width is made smaller than the electrode width of other parts. In the case of this configuration, the member to be charged is arranged so as to receive a current similarly.

FIG. 6 shows a configuration example for explaining a third embodiment of the present invention.

In the configuration example shown in FIG.
Is divided into a plurality of divided electron-emitting portions 30C, and portions other than the electrode portions of each divided electron-emitting portion 30C are covered with an insulator 70. The insulator 70 is formed, for example, as a resin coat made of an insulating resin.

In the third embodiment, only the electron emission electrode surface is left, and resin coating is performed. As a result, an unstable factor such as an alkali metal ion such as sodium ion or moisture does not enter the inside of the chip, thereby enabling a stable operation. For this purpose, a semiconductor-based adhesive with very few impurities or an epoxy-based adhesive can be used as the resin coat. In addition, a polyimide-based material used as an interlayer insulating film or the like is applied. This was developed using a dispenser or the like after the normal manufacturing process was completed.

FIG. 7 is a schematic configuration diagram for explaining an image forming apparatus using the charging device according to the present invention.

Referring to FIG. 7, a charging device 10 according to the present invention will be described.
Is applied to an image forming apparatus. In this example, the image forming apparatus is an electrostatic latent image forming apparatus used as an electrophotographic copying machine or printer.

This image forming apparatus includes a drum-shaped photosensitive member 12 rotatably provided around a central axis O. The photoconductor 12 is a member to be charged which is charged by the electrons and ions emitted from the charging device 10 of the present invention. When the image forming operation is started, the photoconductor 12 is rotated around the central axis O in the direction of arrow S at a constant linear velocity.

In the charging device 10, the arrangement direction A of the plurality of divided electron emission portions 30 of the electron emission element 1 is parallel to the axial direction of the photoconductor 12 (the direction perpendicular to the paper surface), and
The direction T (direction of the arrow T in FIG. 7) perpendicular to the photoconductor 1 is
2 are arranged so as to coincide with the rotation direction (tangential direction). Therefore, even in the case of a photosensitive member having a large width,
Charging unevenness hardly occurs.

Around the photosensitive member 12, the charging device 1
0, a developing roller 16, a transfer charger 14, and a charge removing brush 18 are provided. The photoconductor 12 charged by the charging device 10 is subjected to optical scanning of a light beam generated by the exposure device 20 according to image information, and an electrostatic latent image is recorded on the photoconductor. Developing roller 16 brought close to photoconductor 12
A charged toner is supplied to the surface of the photoconductor 12, and the toner adheres to the electrostatic latent image on the photoconductor 12 to visualize the image. That is, a toner image is formed.

On the other hand, a recording medium 13 (usually, a recording paper is used as a recording medium) is conveyed to the vicinity of the transfer charger 14 of the photoconductor 12 by a paper conveying means (not shown) in synchronization with the recording timing. The recording paper 13 is the photoconductor 12
, The toner image is transferred by the transfer charger 14. The recording paper 13 further includes a fixing roller 20.
And is fixed by the fixing roller 20, and is discharged to a discharge tray provided outside the image forming apparatus. The charge removal brush 18 removes the charge remaining on the photoconductor 12 and prepares for the recharging of the photoconductor 12 by the charging device 10.

As shown in FIG. 7, the charging device 10 of the present invention
Is applied as a charger in an electrophotographic electrostatic latent image forming apparatus, thereby making it possible to configure an image forming apparatus having very little ozone and nitrogen oxides without substantially changing the conventional electrophotographic process. it can. In addition, since the plurality of divided electron-emitting portions of the electron-emitting device are arranged in an arrangement direction parallel to the width direction of the member to be charged, uneven charging can be reduced even when the member to be charged with a large width is charged. It is possible to realize the improved charging efficiency.

[0052]

As described above, according to the charging device of the present invention, since the electron-emitting device for charging the member to be charged by forming negative ions without discharging by low energy electrons is used, , NOx generation is extremely small. In addition, since the electron-emitting device has a configuration in which a plurality of divided electron-emitting portions are arranged in the arrangement direction corresponding to the width direction of the member to be charged, uneven charging is reduced even when the member to be charged with a large width is charged. It is possible to realize the improved charging efficiency.

According to the charging device of the first aspect, a charging device applicable to a large-sized electrophotographic image forming apparatus or the like can be manufactured by a configuration in which the electron-emitting devices are divided and arranged.

In the charging device according to the second aspect, charging unevenness can be reduced by keeping the emission current constant under independent electrical conditions with respect to the chip characteristics of the divided portions.

In the charging device according to the third aspect, the amount of emission current can be controlled by the voltage applied to the element, and this can be used to reduce charging unevenness.

In the charging device according to the fourth aspect, the charging unevenness on the time axis can be further reduced by the feedback based on the charging potential and the toner density, which are actually problematic.

In the charging device according to the fifth aspect, there is no emission current to the gap between the electrodes of the chip. However, since negative ions and the like diffuse in the gas, the charge amount does not suddenly partially decrease. Nevertheless, since there is a change in the level at which charging unevenness occurs, the width is adjusted according to the chip arrangement to correct the change, thereby enabling uniform charging.

In the charging device according to the sixth aspect, there is no emission current to the space between the electrodes of the chip. However, since negative ions and the like diffuse in the gas, the charge amount does not suddenly partially decrease. Even so, there is a change in the level at which charging unevenness occurs, so that the width can be increased and uniformized to correct it.

In the charging device according to the present invention, a plurality of chips are placed in the direction of the linear velocity in order to reduce unevenness between the chips, but the ends of the electrodes are narrowed in order to adjust the total charge amount. , Can be uniformly charged.

In the charging device according to the eighth aspect, by preventing the deterioration due to the entry of moisture, air, etc. into the chip with an insulator, it is possible to prevent the discharge at the electrode portion and the like and the deterioration of the chip.

In the charging device according to the ninth aspect, by preventing the deterioration due to the entry of moisture, air, etc. into the chip with an insulator, it is possible to prevent the discharge at the electrode and the like and the deterioration of the chip. Since this is performed using a resin, it is possible to easily mount another functional chip on the substrate.

According to the tenth aspect of the present invention, by using the charging device according to the first to ninth aspects, it is possible to constitute an electrophotographic type image forming apparatus with less generation of ozone and NOx, and a deterioration factor of the photosensitive member. Less, longer life,
An environment-friendly image forming apparatus can be created.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration example of an electron-emitting device applied to a charging device according to the present invention.

FIG. 2 is a diagram for explaining negative ionization of an electrically negative gas due to electron emission of the charging device of the present invention.

FIG. 3 is a diagram showing a configuration example for explaining a first embodiment of the present invention.

FIG. 4 is a diagram showing a configuration example for explaining a second embodiment of the present invention.

FIG. 5 is a diagram showing a configuration example for explaining a third embodiment of the present invention.

FIG. 6 is a diagram showing a configuration example for explaining a fourth embodiment of the present invention.

FIG. 7 is a schematic configuration diagram for explaining an image forming apparatus using the charging device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron emission element 2 Porous semiconductor layer 4 Semiconductor layer 5 Substrate electrode 6 Quartz glass 7 Thin film electrode 8 Power supply 9 Bias power supply 10 Charging device 12 Photoreceptor 31, 32, 33, 34 Split electron emission part 30A, 30B, 30C Split electron Emitting part 51, 52, 53, 54 Insulator

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroyoshi Shoko 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H027 DA02 DA10 EA01 EC06 2H200 FA07 GA23 HA14 HA29 HA30 HB20 HB45 HB46 HB48 MA12 MA20 MB02 MB03 NA01 PA02 PB04 PB18

Claims (10)

[Claims] 1. A charging device, comprising: an electron-emitting device that emits electrons that are energized by an internal electric field, and charges an object having a predetermined width by the electrons emitted by the electron-emitting device. A gas containing an electric negative gas is brought into contact with at least a part of the electron-emitting device, and the object to be charged is charged with the emitted electrons and negative ions generated by molecules of the electric negative gas, and A charging device, wherein the electron-emitting device is divided into a plurality of divided electron-emitting portions, and the plurality of divided electron-emitting portions are arranged in a direction parallel to a width direction of the member to be charged. 2. The charging device according to claim 1, wherein independent electric conditions are set for each of the divided electron-emitting portions of the electron-emitting device. 3. The charging device according to claim 1, further comprising control means for controlling an amount of emission current by controlling a voltage applied to said electron-emitting device. 4. A detecting means for detecting the charged potential or toner concentration of the photosensitive body, wherein the charged body is formed of a photosensitive body, and a voltage applied to the electron-emitting device based on a detection result of the detecting means. 4. The apparatus according to claim 1, further comprising a feedback control mechanism for determining
The charging device according to Item. 5. The charging device according to claim 1, wherein a width of an electrode end in each of the divided electron-emitting portions of the electron-emitting device is changed. 6. An arrangement in which a minute gap is provided in an electrode portion of each divided electron emission portion in a direction perpendicular to a traveling direction of the charged body, and an electrode width of a portion close to the gap is set to another portion. 6. The charging device according to claim 5, wherein the width is larger than the electrode width. 7. A plurality of divided emission portions of the electron-emitting device are arranged in two rows along the traveling direction of the member to be charged, and an electrode width of a portion where the electrode portions of the divided electron emission portions in each row are close to each other is reduced. The charging device according to claim 5, wherein the width of the electrode is smaller than that of the other portions. 8. The charging device according to claim 1, wherein portions of the electron-emitting device other than the electrode portions of each divided electron-emitting portion are covered with an insulator. 9. The charging device according to claim 8, wherein said insulator is made of an insulating resin. 10. An image forming apparatus for forming an image by holding an electrostatic latent image on a photoconductor, wherein the photoconductor is charged by using the charging device according to claim 1. Forming equipment.