JPH09230668A - Image forming device having corona charging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a good reproduction image by controlling air flow flowing into a shield case provided on a corona charging device and contribute to a smooth ion movement. SOLUTION: Respective individual spaces A1, A2 are formed inside laterals 141, 142 integrally formed with the shield case base 14A of a corona charging device 11. The upper stream side is the space A1, the lower stream side is the space A2. A slit 112 is formed on the shield case base 14A facing the space A1 and a slit 113 is formed on the shield case base 14A facing the space A2. The slit 112 formed on the shield base 14A is formed larger than the slit 113 and, when electric discharge starts from a sawtooth shape electric discharge unit 12 to a photosensitive body 101, outside air enters the shield base 14A through the slit 112 as shown with an actual line arrow mark by ion wind of a dashed line arrow mark generated by the electric discharge and helps generation of ion wind. Thus the photosensitive body 101 surface can be provided with specific electric charge at the space A1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a discharged body (hereinafter referred to as a photosensitive body) in an electrophotographic image forming apparatus.
The present invention relates to a corona charging device using a non-contact type sawtooth electrode used for the purpose of charging.

[0002]

2. Description of the Related Art Conventionally, discharge means for performing electrophotographic corona discharge are roughly classified into a wire discharge method (corotron, scorotron, dicorotron, etc.) and a needle discharge method (pin electrode type, sawtooth electrode type, etc.). To be done. The latter has come to be used in electrophotographic copying machines, printers, etc. in recent years due to its low ozone generation amount. In particular, a charger having a structure using an electrode plate in which a plurality of sawtooth-shaped electrode portions are provided on one thin plate member is disclosed in JP-A-63-15272 and JP-A-5-157272.
It is disclosed in Japanese Patent Publication No. 45999. A structure in which the serrated electrode portion is held by a part of the corona charging device main body and is detachable is disclosed in Japanese Patent Laid-Open No. 5-289471, and both side surfaces of the serrated electrode portion are entirely held. The structure is disclosed in JP-A-6-83167. Further, Japanese Patent Laid-Open No. 7-84440 discloses a structure in which a sawtooth electrode portion is supported by a supporting member.

Japanese Patent Laid-Open No. 7-92766 discloses a method of removing ozone generated from the electrode portion from the direction of the discharged body in a charger having a structure using an electrode plate provided with a serrated electrode portion. ing. 13 and 14 are a perspective view and a cross-sectional view showing a main body of a corona charging device which has been conventionally used.

[0004]

Generally, as shown in FIGS. 13 and 14, a corona charging device (hereinafter referred to as a corona charging device) for applying an electric charge to the surface of the photoconductor has a wire or a wire provided in the corona charging device. A high voltage of 5 KV to 10 KV is applied to the needle-shaped electrode, ions or electrons are moved to the surface of the photoconductor by corona discharge to give an electric charge, and the surface of the photoconductor is charged so as to maintain a constant potential. There is.
As shown in FIG. 14, in the corona charger 11 that performs a charging operation, a saw-tooth discharge unit 12 is formed on a plate electrode 13 formed of a thin metal plate in a shield case 14 formed in a U-shaped cross section. , The plate electrode 13 in the shield case 1
4, the plate-shaped electrode support member 131 formed in an L-shape is fixed at one end in the shield case 14, and the saw-toothed electrode 12 is arranged at the other end with the saw-tooth electrode 12 on the discharge direction side. To provide.

Further, it is possible to prevent external dust particles or scattered toner particles of the developer from entering the saw-tooth discharge portion 12 of the plate electrode 13, and further, to prevent the charge erasing lamp provided in the vicinity of the corona charger 11. Shield case 14 so as not to be affected
Both side portions of are provided close to the surface of the photoconductor 101. When the photoconductor 101 is charged by using the corona charger 11 configured as described above, external air enters from the direction of the solid arrow shown in FIG.
By the discharge from the sawtooth discharge portion 12 of 3, the ions move in the direction of the one-dot chain line arrow, and the photosensitive member 101 is charged. However, as indicated by the arrow, the flow of air and ions is divided into two by the plate-shaped electrode support member 131 and the plate-shaped electrode 13, so that the shield case 1 with respect to the rotation direction of the photoconductor 101 is separated.
Since the upstream side and the downstream side of 4 do not interact with each other and the upstream side is blocked in particular, it is difficult for ions to move smoothly. Therefore, charge may not be applied to the surface of the photoconductor at a predetermined charge value. The generated ozone also stays in the shield case 14 and adversely affects the photoconductor 101.

Further, as a means for preventing the convection of ozone,
Although Japanese Patent Laid-Open No. 7-92766 is disclosed,
The effect of smoothing the movement of ions has not been solved.

Further, as shown in FIG. 13, the corona charger 11 is formed to be laterally long with respect to the direction of the rotation axis of the photoconductor 101, and both ends of the shield case support members 1111 and 1121 are subjected to a charging operation. As for the air flow in the shield case 14 supported by, a large amount of air flows in from both ends of the corona charger 11, and the air inflow is small in the central part, so that the ionic wind changes and uniform charging cannot be performed. . Furthermore, when air flows in from both ends of the corona charger 11, dust enters from the outside and adheres to the saw-tooth discharge parts 12 on both sides to reduce the charging efficiency.

The present invention provides a good copy image by improving the air flow flowing into the shield case provided in the corona charger to smoothly move the ions and always maintain the normal charging action. The purpose is to do.

[0009]

According to the present invention, there is provided a metal frame body comprising a base portion and side portions integrally formed to face the base portion. The sawtooth discharge part of the plate electrode provided in the body is opposed to the discharged body,
In a corona charging device for discharging the discharged body, formed to allow air outside to flow from the metal frame body at both upstream and downstream positions of the plate electrode provided in the metal frame body. A plurality of openings provided, and the plurality of openings are
3. The opening of the downstream side is formed so as to have a small opening ratio with respect to the opening of the upstream side, wherein the plurality of openings are the base of the metal frame body. The reinforcing rib is formed in the plurality of openings formed in the base portion of the metal frame, and the reinforcing rib is formed in the opening on the upstream side. The number of reinforcing ribs formed in the opening on the downstream side is large, and the base has a metal frame body formed of a side portion integrally formed with the base portion according to claim 4, In a corona charging device in which a saw-tooth discharge portion of a plate-shaped electrode provided in a metal frame is opposed to an object to be discharged and a discharge is performed on the object to be discharged, an upstream of the plate-shaped electrode provided in the metal frame On the side, an opening formed for allowing the outside air to flow in from the metal frame, and the metal frame The exhaust opening is provided on one of the side portions located on the upstream side, and one end of the side portion located on the downstream side of the metal frame is configured to be close to the surface of the discharged body. 7. The exhaust opening provided at one end of the side portion of the metal frame body according to claim 6, wherein the opening portion provided on the upstream side of the plate electrode is formed at the base portion of the metal frame body. The portion is provided between the side portion and the body to be discharged, and in claim 7, the portion has a metal frame body including a base portion and a side portion integrally formed with the base portion to face each other. In a corona charging device that discharges an object to be discharged by causing the saw-tooth discharge portion of the plate electrode provided in the metal frame to face the object to be discharged, A plurality of openings formed at the both sides of the upstream side and the downstream side for allowing the air outside from the metal frame body to flow in. And an exhaust guide means having an exhaust opening formed at one end of a side plate located on the upstream side of the metal frame body, and one end of the side part located on the downstream side of the metal frame body is provided on the surface of the discharged body. 9. The exhaust guide means according to claim 8, wherein the plurality of openings are formed in a base portion of the metal frame body, and the exhaust guide means having the exhaust opening portion is formed from the side portion. 10. The metal frame body according to claim 9, wherein the metal frame body is provided outside and is formed between the discharged bodies, the metal frame body having a base portion and side portions integrally formed to face the base portion. The sawtooth discharge part of the plate electrode provided in the metal frame is opposed to the discharged body,
In a corona charging device for discharging the discharged body, formed to allow air outside to flow from the metal frame body at both upstream and downstream positions of the plate electrode provided in the metal frame body. The plurality of openings, the exhaust opening provided at one end of the side portion located on the upstream side of the metal frame body, and the one end of the side portion located on the downstream side of the metal frame body to be discharged. The exhaust guide means formed toward the upstream side is provided while being close to the body surface, and the plurality of openings are formed in the base portion of the metal frame body according to claim 10, The exhaust opening formed in the side portion is formed between the side portion and the discharged body.
In 1, there is provided a metal frame body having a base portion and a side portion integrally formed to face the base portion, and the sawtooth discharge portion of the plate electrode provided in the metal frame body is made to face the discharged body. In a corona charging device for discharging the discharged material, at both upstream and downstream positions of the plate electrode provided in the metal frame,
A plurality of openings formed to allow the outside air to flow in from the metal frame, an exhaust opening provided at one end of a side part located on the upstream side of the metal frame, and the metal frame The elastic shield member provided on the side portion located on the downstream side and in contact with the surface of the discharged body is provided.
14. In 2, the plurality of openings are formed in the base, and the exhaust opening formed in the side is formed between the side and the discharged body.
Between the elastic shield member provided on the side portion located on the downstream side of the metal frame body and brought into contact with the surface of the discharge target body, both end openings of the metal frame body, and the discharge target body. This is achieved by providing a brush-shaped shielding member.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of an embodiment of the present invention, the structure of a copying apparatus using a corona charger of the present invention and its operation will be described.

In FIG. 1, reference numeral 10 denotes a photosensitive drum, which is an image bearing member, which is formed by coating a photosensitive member 101 (organic photosensitive member) on a drum substrate, and is grounded and driven to rotate clockwise in the drawing. To be done. Reference numeral 11 denotes a corona charger. The corona charger 11 is composed of a plate electrode 13 having a sawtooth discharge portion 12, and is exposed to light from a discharge portion 12 provided in a shield case 14 made of a metal frame. The surface of the body 101 is charged with an electric charge. Prior to the charging operation, in order to eliminate the history of the photosensitive member 101 up to the previous printing, the photosensitive member 101 is discharged by exposure by a PCL (pre-charging static eliminator) 15 using a light emitting diode or the like.

After the photoconductor drum 10 is uniformly charged on the photoconductor 101, the image exposure means 16 performs image exposure based on an original image or an image signal, and then performs image reduction and enlargement. At times, the charge is removed by a CEL (unnecessary charging unit charge eliminator) 15A for removing unnecessary charges from the surface of the photoconductor 101. Next, on the surface of the photoconductor 101 of the photoconductor drum 10, there is provided a developing device 17 in which a developer containing a toner and a carrier is housed, and a developing sleeve 18 which houses a magnet and rotates while holding the developer. Is developed by. The developer consists of a carrier in which ferrite is used as a core and is coated with an insulating resin around it, and a toner whose main material is polyester and pigment and a charge control agent, silica, titanium oxide, etc. are added. The layer is regulated to have a layer thickness (developer) of 0.1 to 0.6 mm on the developing sleeve 18 by the means and is conveyed to the developing area.

The gap between the developing sleeve 18 and the photoreceptor 101 in the developing area is 0.2 to larger than the layer thickness (developer).
The bias voltage is applied during this time. Thus, the image forming process is performed by the developer, and a visible image is formed by the toner on the peripheral surface of the photoconductor 101.

On the other hand, although not shown, a sheet of transfer material (hereinafter referred to as recording paper) P conveyed by a conveying member 21 from a sheet feeding cassette via a sheet feeding roller is temporarily stopped by a stop member 19.
When the transfer timing is adjusted, the stop member 19 is operated by the operating means 20 to release the recording paper P, and the registration roller 2
The sheet is fed to the transfer area by the rotation operation of 11.

In the transfer area, in synchronization with the transfer timing, the recording paper P fed by the transfer pole 22 serving as a transfer means is sandwiched around the peripheral surface of the photosensitive body 101 of the photosensitive drum 10 to form a toner image. Is transcribed.

Then, the recording paper P is destaticized by the separating pole 23, separated from the peripheral surface of the photosensitive drum 10, and then conveyed to the fixing device 24 to be heated roller (upper roller) 25 and pressure roller (lower roller) 26. After the toner is fused by heating and pressurizing, the toner is discharged to the outside of the apparatus. On the other hand, the photosensitive drum 10 from which the recording paper P has been separated removes and cleans the residual toner by pressing the blade 28 of the cleaning device 27.
The PCL (pre-charging static eliminator) 15 again removes electricity, and the corona charger 11 receives the charge to start the next image forming process.

FIG. 2 is a cross-sectional view showing a concrete first embodiment of the corona charger 11 of the present invention.

In FIG. 2, the plate electrode 13 having the saw-tooth discharge portion 12 for charging the photosensitive member 101 is made of a stainless material having a thickness of about 0.1 mm and is formed by etching. , A large number of sawtooth discharge parts 12 are formed at equal intervals on the side edge of the photoconductor drum 10 which is the object to be discharged facing the image area of the photoconductor 101 so as to face the surface of the photoconductor 101 with a predetermined gap. is set up.

Further, the shield case 1 of the corona charger 11
Reference numeral 4 denotes a shield case base portion 14A and side portions 141, 142 integrally formed with the shield case base portion 14A, which are formed by a metal frame body having a U-shaped cross section, and a substantially central portion in the shield case base portion 14A. One end of the support member 131 made of an L-shaped insulator is fixed to the. As a fixing method, an adhesive or the like is used for fixing. Then, the plate-shaped electrode 13 is fixed to a part of the support member 131 with the fixing screw 132 at the position where the saw-tooth discharge portion 12 is adjusted to a predetermined position. With the above structure, separate space portions A1 and A2 are formed in the side portions 141 and 142 integrally formed with the shield case base portion 14A.

Hereinafter, the space A1 is located upstream of the corona charger 11 in the initial direction of charging with respect to the rotation direction of the photoconductor 101, and the space A2 is corona charger 11 with respect to the rotation direction of the photoconductor 101. It is located on the downstream side of the latter stage of charging. That is, the upstream side is the space portion A1. The downstream side is defined as the space portion A2.

A slit 112 is provided in the shield case base 14A corresponding to the space A1 in the space A2.
Slits 113 are formed in the shield case base 14A corresponding to the above.

Next, the operation of the embodiment of the present invention will be described with reference to FIGS. 4 (a), 4 (b) and 4 (c). As shown in FIG. 4A, the slit 112 of the space A1 is formed with a width L and the slit 113 is formed around the saw-tooth discharge portion 12 formed in the plate electrode 13 provided at the YY line position. Each is formed with a width L1. The width L and the width L1 are L> L1
It is formed so that it becomes. Further, as shown in the figure, the side portion 14 integrally formed with the shield case base portion 14A.
The positions of the tips of 1, 142 and the photoconductor 101 are a and b, respectively. FIG. 4B shows a discharge distribution when the sawtooth discharge portion 12 formed on the plate electrode 13 is corona-discharged. That is, when the position of the saw-toothed discharge portion 12 is taken along the line Y-Y,
The discharge distribution of the sawtooth discharge portion 12 located on the −Y line is highest, and the photoconductor 1 is located at the tip positions of the side portions 141 and 142.
The a and b positions of 01 are the lowest. FIG. 4C shows the amount of potential on the surface of the photoconductor 101 when corona discharge is performed by the sawtooth discharge unit 12. As shown in the figure, the potential amount is substantially zero at the position a corresponding to the side portion 141, and the potential amount increases as it approaches the YY line where the sawtooth discharge portion 12 is located, and corresponds to the side portion 142 b. Maximum potential at position. That is, the surface of the photoconductor 101 reaches the predetermined maximum potential amount for the first time in the space A2 after passing the YY line. Therefore, if the flow of the ionic wind is poor, the charging performance becomes uneven. Therefore, the width L of the slit 112 formed in the shield case base 14A and the width L1 of the slit 113 are set to L>
A uniform ionic wind is obtained by forming L1.

As shown in FIG. 2, the shield case base 1
The slit 112 formed in 4A is formed to be larger than the slit 113, and when discharge is started from the sawtooth discharge part 12 to the photoconductor 101, a solid line is drawn from the slit 112 by the ion wind indicated by the alternate long and short dash line arrow. The outside air enters as shown by the arrow and helps the generation of ionic wind.
Therefore, a predetermined charge can be applied to the surface of the photoconductor 101 in the space A1. Further, electric charges are applied to the surface of the photoconductor 101 by the discharge from the sawtooth discharge portion 12, and then the slit 1
The outside air shown by the solid line arrow 13 enters the space A2, but the slit 113 is formed smaller than the slit 112, and the generation of ionic wind is slightly inferior as shown by the one-dot chain line arrow, but inside the space A1. Since the amount of electric charge is given by the charging in (1), a predetermined electric charge is stably given while the photoconductor 101 passes through the corona charger 11.

FIG. 3 is a perspective view showing a part of the corona charger 11 of FIG.
Another structure for changing the inflow of air from the slits 112 and 113 formed in 4A is shown. As shown in the figure, the slit 112 is formed with a reinforcing rib 1141 at one place,
Two reinforcing ribs 1151 are formed in one slit 113. By changing the number of the reinforcing ribs 1141 and 1151 in this way, the inflow amount of air from the slits 112 and 113 can be changed. The side portions 141 and 142 formed integrally with the shield case base portion 14A are shield case support members 1111 and 112 made of an insulator.
1, both ends of which are fixed and held, and the shield case support member 1121 is provided with a connection terminal 14B.
3 and the high voltage part.

Next, FIG. 5 shows a corona charger 1 according to the present invention.
1 shows another embodiment.

As in FIG. 2, the plate electrode 13 having the saw-tooth discharge portion 12 for charging the photosensitive member 101 is made of a stainless material having a thickness of about 0.1 mm, and is formed by etching. A large number of saw-tooth discharge parts 12 are formed at equal intervals on the side edge of the photoconductor drum 10, which is the discharged body, facing the image area of the photoconductor 101, and are installed so as to face the surface of the photoconductor 101 with a predetermined gap. Has been done.

Further, the shield case 1 of the corona charger 11
Reference numeral 4 denotes a shield case base portion 14A and side portions 141, 142 integrally formed with the shield case base portion 14A, which are formed by a metal frame body having a U-shaped cross section, and a substantially central portion in the shield case base portion 14A. One end of the support member 131 made of an L-shaped insulator is fixed to the. As a fixing method, an adhesive or the like is used for fixing. Then, the plate electrode 13 is fixed to a part of the support member 131 with a fixing screw 132 at a position where the sawtooth discharge portion 12 is adjusted to a predetermined position. Further, an air exhaust opening 143 is formed between the end of the side portion 141 and the surface of the photoconductor 101. Further, the end portion of the side portion 142 is formed close to the surface of the photoconductor 101. By configuring as above,
Side 1 integrally formed with the shield case base 14A
Separate spaces A1 and A2 are formed in 41 and 142, respectively, and slits 114 are formed in the shield case base 14A corresponding to the spaces A1. Reference numeral 15A denotes the CEL (unnecessary charging portion static eliminator), which is arranged outside the side portion 142 and close to the surface of the photoconductor 101.

Next, the sawtooth discharge section 12 is used to remove the photosensitive member 10.
When the discharge is started at 1, the outside air enters from the slit 114 as indicated by the solid line arrow due to the ion wind indicated by the one-dot chain line arrow generated by the discharge to help the generation of the ion wind. Furthermore, since the ion wind is discharged from the exhaust air opening 143 formed in the side portion 141 together with the outside air, the photoconductor 10 is discharged in the space A1.
It is possible to reliably apply a predetermined charge to one surface. Further, charges are applied to the surface of the photoconductor 101 by discharge from the saw-tooth discharge part 12, and the ionic wind generated in the space A2 is also smoothly discharged from the exhaust opening 143 and charges are applied. At this time, since the tip of the side portion 142 forming the space A2 is provided close to the surface of the photoconductor 101, the outside air does not enter from the tip of the side portion 142 due to the exhaust action, and therefore dust and scatter. In order to prevent the invasion of the developer and the like, the dust and scattered developer and the like do not adhere to the tip of the sawtooth discharge portion 12 and can withstand long-term use.
There is no adverse effect on the EL (unnecessary electrification part static eliminator) 15A.

FIG. 6 is a perspective view of the corona charger 11 of FIG. 5 with a part cut away, showing a slit 114 formed in the shield case base 14A having a U-shaped cross section. Shield case supporting members 1111 and 1121 made of an insulating material are fixedly held at both ends of the side portions 141 and 142 formed integrally with each other.
B is provided so as to be connected to the plate electrode 13 and the high voltage portion.

FIGS. 7A and 7B show another embodiment of the corona charger 11 according to the present invention.

In FIG. 7A, a plate electrode 13 having a saw-tooth discharge portion 12 for charging the photoconductor 101 is formed.
Is made of a stainless material having a thickness of about 0.1 mm as described above, and is formed by etching. A large number of sawtooth discharges are formed on a side edge of the photosensitive drum 101, which is a discharged body, facing the image area of the photosensitive drum 101. The portions 12 are formed at equal intervals and are installed so as to face the surface of the photoconductor 101 with a predetermined gap.

Further, the shield case 1 of the corona charger 11
Reference numeral 4 denotes a shield case base portion 14A and side portions 141, 142 integrally formed with the shield case base portion 14A, which are formed by a metal frame body having a U-shaped cross section, and a substantially central portion in the shield case base portion 14A. One end of the support member 131 made of an L-shaped insulator is fixed to the. As a fixing method, an adhesive or the like is used for fixing. Then, the plate electrode 13 is fixed to a part of the support member 131 with a fixing screw 132 at a position where the sawtooth discharge portion 12 is adjusted to a predetermined position. Further, an exhaust guide plate 144 is integrally formed at one end of the side portion 141 with a distance from the surface of the photoconductor 101 and outwardly, and an exhaust opening is formed between the exhaust guide plate 144 and the surface of the photoconductor 101. The portion 1441 is formed.

One end of the side portion 142 is provided so as to be close to the surface of the photosensitive member 101 at a distance L1 of several millimeters. With the above configuration, the side portions 141, 142 integrally formed with the shield case base portion 14A.
Separate space portions A1 and A2 are formed therein.

A slit 115 is formed in the shield case base 14A corresponding to the space A1 and a slit 116 is formed in the shield case base 14A corresponding to the space A2.

FIG. 7 (b) has the same structure as FIG. 7 (a), but one end of the side portion 141 is slightly spaced from the surface of the photosensitive member 101, and the exhaust guide is directed outward. Although the plate 144 is integrally formed, in the present embodiment, the exhaust guide plate 144 is curved outward toward the outside in order to smooth the exhaust and to exhaust the gas from the exhaust opening 1441. Form.

When electric discharge is started from the saw-tooth electric discharge portion 12 constructed as shown in FIGS. 7 (a) and 7 (b) to the photoconductor 101 in the direction of the one-dot chain line arrow, the one-dot chain line arrow generated by the electric discharge is shown. The outside air enters from the slit 115 as indicated by the solid line arrow by the above ion wind to assist the generation of the ion wind, and the exhaust guide plate 144 formed at one end of the side portion 141.
As a result, the gas is smoothly exhausted to the outside from the exhaust opening 1441, so that the ion wind is further generated to increase the charging efficiency. Therefore, a predetermined charge can be applied to the surface of the photoconductor 101 in the space A1. Further, electric charges are applied to the surface of the photoconductor 101 by the discharge from the saw-tooth discharge portion 12, and then the outside air indicated by the solid line arrow enters the space A2 through the slit 116, and as shown by the dashed line arrow from the slit 116. Ion wind is further generated, and charges are reliably applied to the photoconductor 101. In this way, predetermined charges are stably applied while the photoconductor 101 passes through the corona charger 11.

Also in this embodiment, as in the case of FIG.
The tip of the side portion 142 that forms the space portion A2 is the photosensitive member 10
Since it is provided close to one surface, outside air does not enter from the tip of the side portion 142 due to the exhaust action. Therefore, in order to prevent the dust and the scattered developer from entering, the dust and the scattered developer do not adhere to the tip of the sawtooth discharge portion 12, and it is possible to withstand long-term use and
(Unnecessary charging portion static eliminator) 15A is not adversely affected.

FIG. 8 is a perspective view showing the corona charger 11 shown in FIGS. 7 (a) and 7 (b) by cutting away a part thereof, which is formed on the shield case base 14A having a U-shaped cross section. The slits 115 and 116 are shown, and at both ends of the side portions 141 and 142 integrally formed with the shield case base portion 14A, a shield case support member 111 made of an insulator is provided.
1, 1121 are fixedly held, and a connection terminal 14B is provided on the shield case support member 1121 so as to connect the plate electrode 13 and the high voltage portion.

9A and 9B show another embodiment of the corona charger 11 of the present invention.

In FIG. 9A, the plate electrode 13 having the saw-tooth discharge portion 12 for charging the photoconductor 101 is formed.
Similarly to the above, is made of a stainless steel material having a thickness of about 0.1 mm, is formed by etching, and has a large number of sawtooth-shaped edges on the side edge of the photosensitive drum 101, which is the discharged body, facing the image area of the photosensitive drum 101. The discharge parts 12 are formed at equal intervals,
It is installed so as to face the surface of the photoconductor 101 with a predetermined gap.

Further, the shield case 1 of the corona charger 11
Reference numeral 4 denotes a shield case base portion 14A and side portions 141, 142 integrally formed with the shield case base portion 14A, which are formed by a metal frame body having a U-shaped cross section, and a substantially central portion in the shield case base portion 14A. One end of the support member 131 made of an L-shaped insulator is fixed to the. As a fixing method, an adhesive or the like is used for fixing. Then, the plate electrode 13 is fixed to a part of the support member 131 with a fixing screw 132 at a position where the sawtooth discharge portion 12 is adjusted to a predetermined position. The tip of the side portion 141 is separated from the surface of the photoconductor 101 to form an exhaust opening portion 1411 and a part of the end of the side portion 142 is bent inward to form an exhaust guide plate 145. The tip of the guide plate 145 is provided so as to be close to the surface of the photoconductor 101. With the above configuration, the side portion 14 formed integrally with the shield case base portion 14A.
Separate space portions A1 and A2 are formed in the insides of 1 and 142, respectively.

A slit 117 is formed in the shield case base 14A corresponding to the space A1, and a slit 118 is formed in the shield case base 14A corresponding to the space A2.

FIG. 9 (b) has the same configuration as that of FIG. 9 (a). The exhaust guide plate 145, which is formed at one end of the side portion 142 and has a tip close to the surface of the photoconductor 101 and is integrally formed inward, is provided in the present embodiment in order to facilitate exhaust. 145 is formed in a curved shape toward the inside.

Corona charger 11 constructed as described above
When electric discharge is started from the sawtooth discharge part 12 to the photoconductor 101 in the direction indicated by the alternate long and short dash line, outside air enters from the slit 117 as indicated by the solid arrow by the ion wind indicated by the alternate long and short dash line arrow. In addition to helping the generation of ion wind, the air is smoothly exhausted in the direction of the solid arrow from the exhaust opening 1411 formed between one end of the side portion 141 and the surface of the photoconductor 101, so that the ion wind is good. Then, a predetermined amount of electric charge is applied to the surface of the photoconductor 101. Further, the outside air enters from the slit 118 as shown by the solid line arrow by the ion wind generated by the discharge of the saw-tooth discharge portion 12, and the exhaust guide plate 145 in which the ion wind shown by the dashed line arrow is bent inward as described above.
Since the gas is smoothly exhausted through the exhaust opening 1411 of the side portion 141, the charging efficiency is further increased by the generation of ion wind. In this way, the photosensitive member 1 in the space A1
01 surface is given a predetermined charge, and further, the sawtooth discharge section 12 discharges the charge to the surface of the photosensitive member 101, and then the outside air indicated by the solid arrow from the slit 118 is a space portion A.
2, the ion wind is further generated from the slit 118 as shown by the dashed line arrow, and the charge is surely applied to the photoconductor 101. In this way, predetermined charges are stably applied while the photoconductor 101 passes through the corona charger 11.

Also in this embodiment, as in the case of FIG.
The tip of the side portion 142 that forms the space portion A2 is the photosensitive member 10
Since it is provided close to one surface, outside air does not enter from the tip of the side portion 142 due to the exhaust action, and therefore dust and scattered developer are prevented from entering, so that the sawtooth discharge portion 12 is provided.
The dust, scattered developer, and the like do not adhere to the tip of the sheet, and it can withstand long-term use, and does not adversely affect the CEL (unnecessary electrified portion static eliminator) 15A.

FIG. 10 is a perspective view showing a part of the corona charger 11 shown in FIGS. 9 (a) and 9 (b) by cutting away.
The slits 117 and 118 formed in the shield case base 14A having a U-shaped cross section are shown, and the shield case support member 11 made of an insulator is provided at both ends of the side portions 141 and 142 integrally formed with the shield case base 14A.
11, 1121 are fixedly held, and a connection terminal 14B is provided on the shield case support member 1121 so as to connect the plate electrode 13 and the high voltage portion.

11 (a) and 11 (b) show another embodiment of the corona charger 11 of the present invention.

In FIG. 11A, the plate-like electrode 13 having the saw-tooth discharge portion 12 for charging the photosensitive member 101 as described above is made of a stainless material having a thickness of about 0.1 mm. A large number of sawtooth discharge parts 12 are formed at equal intervals on the side edge of the photoconductor drum 10, which is an object to be discharged, facing the image area of the photoconductor drum 10, which is formed by etching, and is formed with a predetermined gap from the surface of the photoconductor 101. Are installed to face each other.

Further, the shield case 1 of the corona charger 11
Reference numeral 4 denotes a shield case base portion 14A and side portions 141, 142 integrally formed with the shield case base portion 14A, which are formed by a metal frame body having a U-shaped cross section, and a substantially central portion in the shield case base portion 14A. One end of the support member 131 made of an L-shaped insulator is fixed to the. As a fixing method, an adhesive or the like is used for fixing. Then, the plate electrode 13 is fixed to a part of the support member 131 with a fixing screw 132 at a position where the sawtooth discharge portion 12 is adjusted to a predetermined position. An exhaust opening 14 is provided between the tip of the side portion 141 and the surface of the photoconductor 101.
12, an end portion of the side portion 142 is adhered and fixed to the end portion of the side portion 142, and the other end of the elastic seal member 1 is always in contact with the surface of the photoconductor 101.
48 are provided. Specifically, the elastic seal member 1
For 48, urethane rubber or the like that does not affect the latent image formed on the photoconductor 101 is used.

Further, as shown in FIG. 12, the shield case base member 14A and the shield case support members 1111 and 1121 made of an insulating material are provided at the respective ends of the shield case formed by the side portions 141 and 142 and having a U-shaped cross section. It is fixedly held and the shield case support member 1111 is
Brush-shaped protection members 146 and 147, one end of which is fixed to 1121 and the other end of which is in contact with the surface of the photoconductor 101, are provided.

With the above structure, the side portion 141 formed integrally with the shield case base portion 14A.
Separate spaces A1 and A2 are formed in 142.

A slit 119 is formed in the shield case base 14A corresponding to the space A1 and a slit 120 is formed in the shield case base 14A corresponding to the space A2.

FIG. 11B is a perspective view showing a cutaway part of the corona charger 11 shown in FIGS. 11A and 12 and shows the shield case base 14A having a U-shaped cross section. The formed slits 119 and 120 are shown, and the side portion 14 integrally formed with the shield case base portion 14A is shown.
As described above, shield case support members 1111 and 1121 made of an insulator are fixedly held at both ends of 1, 142, and the shield case support member 1121 is provided with connection terminals 14B, and is connected to the plate-like electrode 13 and a high terminal. An elastic seal member 148, which is provided so as to be connected to the voltage portion and fixed to the side portion 142, is provided on the entire surface of the end of the side portion 142 as shown in the drawing.

Corona charger 11 constructed as described above
When electric discharge is started from the sawtooth electric discharge portion 12 to the photoconductor 101 in the direction indicated by the alternate long and short dash line, the external air is generated from the slit 119 by the ion wind indicated by the alternate long and short dash line as indicated by the solid line arrow. Since it enters A1 and assists the generation of ionic wind, and a predetermined gap is formed between one end of the side portion 141 and the surface of the photoconductor 101, air is more smoothly discharged in the direction indicated by the solid line arrow. Ionic wind is generated favorably, and a predetermined amount of electric charge is applied to the surface of the photoconductor 101. Further, the slit 1 is formed by the ion wind generated by the discharge of the sawtooth discharge section 12.
20, the outside air enters as indicated by the solid line arrow, and the ion wind indicated by the alternate long and short dash line indicates the elastic seal member 148 provided on the side portion 142 and the shield case support members 1111 and 112.
1 has one end fixed to it and the other end is in contact with the surface of the photoconductor 101 by brush-shaped shielding members 146 and 147, which is smoother than the exhaust opening 1412 formed between the end of the side 141 and the surface of the photoconductor 101. Since it is exhausted to the above, a better ion wind flow can be obtained.

Next, the outside air indicated by the solid line arrow enters the space A2 through the slit 118, and the ion wind is generated through the slit 118 as indicated by the alternate long and short dash line arrow so that the charge is surely applied to the photoconductor 101. It In this way, corona charger 1
Predetermined charges are stably applied while the photoconductor 101 passes through 1.

Further, in this embodiment, as described above, the elastic seal member 148 and the brush-like protective members 146 and 147 prevent the outside air from entering through the tips of the side portions 141 and 142, and thus the dust and scattered developer are scattered. In order to prevent the intrusion of dust and the like, the dust and scattered developer, etc. do not adhere to the tip of the saw-tooth discharge portion 12 and can withstand long-term use.
There is no adverse effect on the EL (unnecessary electrification part static eliminator) 15A.

[0057]

As described above, according to the present invention, the air outside the metal frame body is provided at both upstream and downstream positions of the plate-shaped electrode provided in the metal frame body. A plurality of openings formed to allow the inflow of air, and the plurality of openings are formed with an opening ratio such that the opening on the downstream side is smaller than the opening on the upstream side. Since the ionic wind is flowing in a good state on the upstream side of the first half of the charging, the uniformity of the charging potential can be obtained especially in a halftone image. Furthermore, since the plate-shaped electrode is not easily affected by dust such as a developer, it can withstand long-term use.

In claim 2, the plurality of openings are
Since it is formed at the base of the metal frame, the flow of ion wind is particularly good.

According to a third aspect of the present invention, reinforcing ribs are formed in a plurality of openings formed in the base of the metal frame body, and the downstream side of the reinforcing ribs is formed with respect to the reinforcing rib formed in the upstream side opening. By increasing the number of reinforcing ribs formed in the opening of the ion beam, the ion wind is flowing in a good state on the upstream side of the first half of charging, so that the uniformity of the charging potential can be obtained especially in a halftone image. . Furthermore, since the plate-shaped electrode is not easily affected by dust such as a developer, it can withstand long-term use.

According to a fourth aspect of the present invention, there is provided an opening formed on the upstream side of the plate-shaped electrode provided in the metal frame body for allowing outside air to flow from the metal frame body, and the metal frame body. Since the exhaust opening is provided on one of the side portions located on the upstream side and one end of the side portion located on the downstream side of the metal frame is arranged to be close to the surface of the discharged body, Since the generated ion wind is not blocked on the upstream side, a stable charging potential can be obtained for the photoconductor. In addition, since it was possible to prevent the occurrence of uneven discharge, the air gap between the side and the photoconductor was essentially the exhaust opening, so the toner scattered from the developing section, cleaning device, etc. did not enter, and the plate-like electrode was less contaminated. Therefore, it can withstand long-term use.

In the fifth aspect, the opening provided on the upstream side of the plate electrode is formed on the base portion of the metal frame body, so that the ion wind flow on the upstream side is particularly improved. Therefore, a stable charging potential can be obtained for the photoconductor.

In the sixth aspect, the exhaust opening provided at one end of the side portion of the metal frame body is provided between the side portion and the discharged body, so that it is stable with respect to the photoconductor. The charged potential is obtained. In addition, since it was possible to prevent the occurrence of uneven discharge,
Since the exhaust portion is substantially between the side portion and the photoconductor, the toner scattered from the developing portion, the cleaning device, etc. does not enter, and the plate-like electrode is less contaminated, so that it can withstand long-term use. .

In the present invention, a plurality of openings formed at the upstream side and the downstream side of the plate-shaped electrode provided in the metal frame body for allowing air outside to flow in from the metal frame body. A portion and exhaust guide means having an exhaust opening formed at one end of a side plate located on the upstream side of the metal frame,
Since one end of the side portion located on the downstream side of the metal frame is configured to be close to the surface of the discharged body, since the ion wind generated from the plate-shaped electrode is not blocked on the upstream side, A stable charging potential can be obtained. In addition, since it was possible to prevent the occurrence of uneven discharge, the air gap between the side and the photoconductor was essentially the exhaust opening, so the toner scattered from the developing section, cleaning device, etc. did not enter, and the plate-like electrode was less contaminated. Therefore, it can withstand long-term use.

In the eighth aspect, the plurality of openings are formed at the base of the metal frame body, and the exhaust guide means having the exhaust openings is provided outside the side portion. Further, since it is formed between the discharged members, it is possible to prevent the light of PCL (pre-charging static eliminator) from leaking to the charged region of the photoconductor, and thus a good image can be obtained.

In the ninth aspect, a plurality of openings formed at the upstream side and the downstream side of the plate-shaped electrode provided in the metal frame body to allow the air outside from the metal frame body to flow in. A portion, an exhaust opening provided at one end of a side portion located on the upstream side of the metal frame body, and one end of a side portion located on the downstream side of the metal frame body in proximity to the surface to be discharged. By providing the exhaust guide means formed toward the upstream side, the ion wind generated from the plate electrode is not disturbed on the upstream side, so that a stable charging potential can be obtained for the photoconductor. In addition, since it was possible to prevent the occurrence of uneven discharge,
Since the exhaust portion is substantially formed between the side portion and the photoconductor, the toner scattered from the developing portion, the cleaning device, etc. does not enter, and especially the dust, toner, etc. do not enter from the end portion of the exhaust guide means, Since the dirt on the electrode is reduced, it can withstand long-term use, and since the exhaust guide means is curved inside, when a small-diameter photosensitive drum is arranged,
This is advantageous in terms of design for disposing process members.

In the tenth aspect, the plurality of openings are formed in the base of the metal frame body, and the exhaust opening formed in the side portion is between the side portion and the discharged body. By being formed, the ionic wind generated from the plate-shaped electrode is not blocked on the upstream side, so that a stable charging potential can be obtained for the photoconductor.

In the eleventh aspect of the present invention, a plurality of openings formed at the upstream and downstream positions of the plate-shaped electrode provided in the metal frame body for allowing air outside to flow in from the metal frame body. Section, an exhaust opening provided on one of the side portions located on the upstream side of the metal frame body, and a side portion located on the downstream side of the metal frame body, and contacting the surface of the discharged body. By providing the elastic shielding member, the flow of the ionic wind generated from the plate-shaped electrode is not obstructed, so that the stability of the charging potential with respect to the photoconductor can be obtained, and there is no uneven discharge, Since the exhaust opening at the end is substantially an exhaust port, dust and suction of toner scattering of the developing unit and the cleaning device are eliminated, and the plate-like electrode is prevented from being contaminated. You can

In the twelfth aspect, the plurality of openings are formed in the base portion, and the exhaust opening formed in the side portion is formed between the side portion and the discharged body. As a result, the ionic wind generated from the plate-shaped electrode is not disturbed on the upstream side, so that a stable charging potential can be obtained for the photoconductor.

In the thirteenth aspect, an elastic shielding member provided on the side portion of the metal frame body located on the downstream side and in contact with the surface of the body to be discharged, and both end opening portions of the metal frame body, By providing the brush-like shielding member between the discharged bodies, dust and suction of toner scattering of the developing unit and the cleaning device are eliminated, and the plate electrode is prevented from being soiled, so that a good charging action can be obtained for a long period of time. You can

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of an image forming apparatus using a corona charger according to the present invention.

FIG. 2 is a cross-sectional view of the corona charger of the present invention.

FIG. 3 is a perspective view showing the corona charger of FIG. 2 of the present invention.

FIG. 4 is an explanatory view showing an opening width of a shield case and a charging action in the corona charger of the present invention.

FIG. 5 is a cross-sectional view showing another corona charger according to the present invention.

FIG. 6 is a perspective view showing the corona charger of FIG. 5 of the present invention.

FIG. 7 is a cross-sectional view showing another corona charger according to the present invention.

FIG. 8 is a perspective view showing the corona charger of FIG. 7 of the present invention.

FIG. 9 is a cross-sectional view showing another corona charger according to the present invention.

FIG. 10 is a perspective view showing the corona charger of FIG. 9 of the present invention.

FIG. 11 is a cross-sectional view and a perspective view showing another corona charger according to the present invention.

FIG. 12 is a side view showing the corona charger of FIG. 11 of the present invention.

FIG. 13 is a perspective view showing a conventional corona charger.

FIG. 14 is a cross-sectional view showing a conventional corona charger.

[Explanation of symbols]

10 Photoreceptor Drum 101 Photoreceptor 11 Corona Charger 12 Sawtooth Discharge Section 13 Plate Electrode 14 Shield Case 14A Shield Case Base 141,142 Side 17 Developer 1111,1121 Shield Case Support Member 131 Support Member 112,113,114 , 115, 116, 117, 1
18,119,120 Slit A1, A2 Space part

Front page continuation (72) Inventor Yasushi Koshimura 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Stock Company

Claims (13)

[Claims] 1. A metal frame body comprising a base portion and side portions integrally formed to face the base portion, wherein a saw-tooth discharge portion of a plate-shaped electrode provided in the metal frame body faces a body to be discharged. In a corona charging device that discharges the object to be discharged, in order to allow the air outside from the metal frame body to flow into both positions on the upstream side and the downstream side of the plate electrode provided in the metal frame body. A plurality of formed openings are provided, and the plurality of openings are formed with an opening ratio such that the opening on the downstream side is smaller than the opening on the upstream side. An image forming apparatus having a corona charging device. 2. The image forming apparatus having a corona charging device according to claim 1, wherein the plurality of openings are formed in a base portion of the metal frame body. 3. Reinforcement ribs are formed in a plurality of openings formed in the base of the metal frame, and are formed in the opening on the downstream side with respect to the reinforcement ribs formed in the opening on the upstream side. An image forming apparatus having a corona charging device according to claim 1 or 2, wherein a large number of reinforcing ribs are formed. 4. A metal frame body comprising a base portion and side portions integrally formed to face the base portion, wherein a saw-tooth discharge portion of a plate electrode provided in the metal frame body is made to face an object to be discharged. In a corona charging device that discharges the discharged body, an opening formed for inflowing outside air from the metal frame body to an upstream side of the plate-shaped electrode provided in the metal frame body. An exhaust opening is provided on one of the side portions located on the upstream side of the metal frame body, and one end of the side portion located on the downstream side of the metal frame body is arranged to be close to the surface to be discharged. An image forming apparatus having a corona charging device. 5. The image forming apparatus having a corona charging device according to claim 4, wherein the opening provided on the upstream side of the plate electrode is formed in the base of the metal frame. 6. The exhaust opening provided at one end of the side portion of the metal frame body is provided between the side portion and the body to be discharged, according to claim 4 or 5. Image forming apparatus having the corona charging device of. 7. A metal frame body having a base portion and side portions integrally formed to face the base portion, wherein a sawtooth discharge portion of a plate-shaped electrode provided in the metal frame body is made to face an object to be discharged. In a corona charging device that discharges the object to be discharged, in order to allow the air outside from the metal frame body to flow into both positions on the upstream side and the downstream side of the plate electrode provided in the metal frame body. A plurality of openings formed and an exhaust guide means having an exhaust opening formed at one end of the side plate located on the upstream side of the metal frame body, and a side part located on the downstream side of the metal frame body. An image forming apparatus having a corona charging device, characterized in that one end of the corona is arranged to be close to the surface of the discharged body. 8. The plurality of openings are formed at the base of the metal frame, and the exhaust guide means having the exhaust openings is provided outside the side portion and the discharged target It is formed between the bodies, It is characterized by the above-mentioned.
An image forming apparatus having the corona charging device described. 9. A metal frame body comprising a base portion and side portions integrally formed to face the base portion, wherein a saw-tooth discharge portion of a plate electrode provided in the metal frame body is opposed to an object to be discharged. In a corona charging device that discharges the object to be discharged, in order to allow the air outside from the metal frame body to flow into both positions on the upstream side and the downstream side of the plate electrode provided in the metal frame body. The plurality of openings formed, the exhaust opening provided at one end of the side portion located on the upstream side of the metal frame body, and the one end of the side portion located on the downstream side of the metal frame body are covered by the cover. An image forming apparatus having a corona charging device, characterized in that it is provided close to the surface of the discharge body and is provided with an exhaust guide means formed toward the upstream side. 10. The plurality of openings are formed in the base of the metal frame, and the exhaust openings formed in the side are formed between the side and the discharged body. An image forming apparatus having the corona charging device according to claim 9. 11. A metal frame body comprising a base portion and side portions integrally formed to face the base portion, the saw-tooth discharge portion of a plate-shaped electrode provided in the metal frame body facing the discharged body. In a corona charging device that discharges the object to be discharged, in order to allow the air outside from the metal frame body to flow into both positions on the upstream side and the downstream side of the plate electrode provided in the metal frame body. A plurality of openings formed, an exhaust opening provided at one end of the side portion located on the upstream side of the metal frame body, and provided on the side portion located on the downstream side of the metal frame body, An image forming apparatus having a corona charging device, comprising: an elastic shield member that is in contact with the surface of the discharged body. 12. The plurality of openings are formed in the base, and the exhaust openings formed in the side are formed between the side and the body to be discharged. An image forming apparatus comprising the corona charging device according to claim 11. 13. An elastic shielding member, which is provided on a side portion of the metal frame body located on the downstream side and is in contact with the surface of the discharged body, both end openings of the metal frame body, and the space between the discharged bodies. An image forming apparatus having the corona charging device according to claim 11 or 12, wherein a brush-shaped shielding member is provided on the surface of the image forming apparatus.