JP3198917B2 - Image forming apparatus and its charger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a laser beam printer, a facsimile, and a copying machine.

[0002]

2. Description of the Related Art In an image forming apparatus of this type, an electrostatic latent image is formed on the surface of a photosensitive drum as an image carrier, and the image is developed with a developer to be converted into a visible image. The image is transferred to a recording medium such as paper. After the transfer of the visible image, the photosensitive drum is neutralized in preparation for the next formation of an electrostatic latent image, and subsequently charged by a charger. A photosensitive drum, a developing device, a transfer roller, a charger, and the like used in the series of processing are integrated as a process unit, and the process unit is detachable from a main body of the image forming apparatus.
The main body of the apparatus is provided with a drive mechanism for rotating the above-described photosensitive drum and transfer roller, and a control circuit for applying a voltage and the like.These mechanisms and circuits are connected to the process unit when the process unit is mounted on the main body. Connected. As the above-mentioned charger, for example, a so-called scorotron type charger having a charging wire installed along the axial direction of the photosensitive drum is used.

[0003]

When the above-mentioned scorotron-type charger is provided in the process unit, a voltage can be applied to the charging wire provided in the body in order to enable a control circuit on the body to apply a voltage to the charging wire. It is necessary to provide an electrode portion in contact with the contact point on the charger. Further, in order to keep the gap between the photosensitive drum and the charging wire uniform, it is necessary to apply an appropriate tension to the charging wire by a spring member. Further, it is necessary to restrain one end of the charging wire against the tension of the spring member. Conventionally, dedicated members are provided as members constituting the electrode portion, a spring member for applying tension to the charging wire, and a member for restraining one end of the charging wire, so that the number of parts is increased and the cost is increased.

Accordingly, it is an object of the present invention to provide an image forming apparatus and a charger capable of mounting a charging wire with a simple configuration.

[0005]

Hereinafter, the present invention will be described with reference to the drawings showing embodiments of the present invention. However, the present invention is not limited to the illustrated embodiment.

According to the first aspect of the present invention, the main body 10 includes a main body 10 having a control circuit 11, a cylindrical image carrier 50 on which an image is formed on the outer periphery, and a charger 51 for charging the image carrier 50. And a process unit 5 detachably provided to the image forming apparatus.
A pair of protective walls 510 disposed so as to face each other in the axial direction of
And 511, a charging wire 512 which is temporary in parallel to the axial direction of the image carrier 50 between the retaining walls 510 and 511, band
One end of the electric wire 512 is locked to one holding wall 510.
Locking means 514, 514a, 515
A spring means connected to the other end of the main body 12 to apply tension to the charging wire 512; and a contact 10 for a charger provided on the main body 10 when the process unit 5 is mounted on the main body 10.
In an image forming apparatus provided with conducting means for making contact between the contact 100 and the charging wire 512 in contact with the contact member 0, the spring means and the conducting means are integrally provided on a single member 516 and have conductivity. Torsion core made of material
An oil spring 516 is provided as a single member and its screw
The coil portion 516a of the coil spring 516 is the other holding wall.
511 is fitted to a protruding shaft 511c provided on the outer surface side.
And one arm 5 of the torsion coil spring 516
16b is connected to the other end of the charging wire 512,
The arm 516c is extended to a position where it can contact the contact point 100.
It allows to achieve the above object being.

In the present invention, the tension is applied to the charging wire 512 by the single member 516 attached to the charger 51. When the process unit 5 is attached to the main body 10 of the apparatus, the single member 516 comes into contact with the charger contact 100 on the main body 10 side, and the contact 100 and the charging wire 512
Are conducted. One arm 5 of torsion coil spring 516
At 16b, the charging wire 512 is pulled,
The other arm 516c contacts the contact 100 on the main body 10 side.
Thus, the contact 100 and the charging wire 512 are conducted.

According to the second aspect of the present invention, a pair of holding walls 510 and 511 facing each other and a pair of holding walls 510 and 51 are provided.
1 and a charging wire 5
Locking means 514,514a for locking the one end of the 12 on one of the holding wall 510, equipped with 515, and the spring member 516 to provide tension to be connected to the other end of the charging wire 512 charging wire 512, the , Made of conductive material
The torsion coil spring 516 is provided as a spring member.
The coil part 516a of the torsion coil spring 516 is
To the protruding shaft 511c provided on the outer surface side of the holding wall 511
And one of the torsion coil springs 516
Arm 516b is connected to the other end of the charging wire 512.
The charging wire 516 is externally wound around the other arm 516c.
The above-mentioned object is achieved by the charger 51 provided with the electrode portion 516d for connecting to the path 11 .

According to the present invention, the charging wire 5 is provided by the locking means.
One end of the charging wire 12 is locked by one holding wall 510, and the other end of the charging wire 512 is pulled by the spring member 516 from the other holding wall 511. The electrode portion 516d provided at the end of the spring member 516 can be connected to the external circuit 11 to make the external circuit 11 and the charging wire 512 conductive.

According to a third aspect of the present invention, there is provided the image forming apparatus according to the first aspect.
In the device, a locking tool 5 is attached to one end of the charging wire 512.
13 is attached, and one holding wall 510 is provided with a protrusion 514 protruding in a direction opposite to a direction in which the charging wire 512 is pulled out from the holding wall 510, and a locking tool 513 passes through the protrusion 514. A groove 514a having an impossible width is provided .

According to the present invention, when the charging wire 512 is inserted into the groove 514a of the protrusion 514 formed on the holding wall 510 and pulled out in a predetermined direction, the locking member 513 is turned into the groove 5a.
One end of the charging wire 512 is locked to the holding wall 510 by abutting against the protrusion 514 around the periphery 14a.
It is not necessary to fix another member to the holding wall 510 or the like after attaching the charging wire 512 to prevent the charging wire 512 from coming off.

According to a fourth aspect of the present invention, in the image forming apparatus of the third aspect, the process unit 5 is provided with a restraining wall 515 opposed to the protrusion 514 of one of the holding walls 510, and the holding unit 515 holds the process unit 5. The gap S between the wall 510 and the protrusion 514 is set to a minimum value (the plate thickness t of the locking tool 513 in the illustrated example) required to allow the locking tool 513 to pass therethrough or to a value slightly larger than the minimum value. .

In the present invention, the restraining wall 515 and the holding wall 51
The locking member 513 can be moved from one side of the protrusion 514 to the other side via the gap S between the protrusion 514 and the protrusion 514. In this state, when the charging wire 512 is inserted into the groove 514a of the protrusion 514 and pulled in a predetermined direction, the locking tool 513 rises and hits the restraining wall 515 and the protrusion 514 (see FIG. 1). Thereby, the charging wire 513
Is locked to the holding wall 510.

According to a fifth aspect of the present invention, there is provided the charging device of the second aspect.
In addition, a locking tool 513 is provided at one end of the charging wire 512.
The holding wall 510 is attached to one of the holding walls 510.
A protrusion 514 is provided which protrudes in a direction opposite to a direction in which the charging wire 512 is pulled out from the protrusion 10. The protrusion 514 is provided with a groove 514 a having a width through which the locking tool 513 cannot pass.
ing.

According to the present invention, the charging wire 512 is inserted into the groove 514a of the protrusion 514 formed on the holding wall 510, and in this state, the charging wire 512 is pulled out of the holding wall 510 in a predetermined direction and tensioned by the spring means 516. , The locking tool 513 on one end of the charging wire 512
One end of the charging wire 512 is locked to the holding wall 510 as a result of the collision with the protrusion 514 around the periphery 14 a. It is not necessary to fix another member to the holding wall 510 or the like after attaching the charging wire 512 to prevent the charging wire 512 from coming off.

[0016]

7 and 8 show the overall structure of a laser beam printer 1 according to one embodiment of the present invention. In the following, the direction of arrow F in FIG. 7 corresponds to the front of the laser beam printer 1, and the direction of arrow U corresponds to the upper direction. The illustrated laser beam printer 1 includes a main body case 2 and a paper feeding unit 3 for supplying paper P.
A laser scanner unit 4 for forming an electrostatic latent image, a process unit 5 for converting the electrostatic latent image into a visible image and transferring it to a sheet P, and fixing the image transferred to the sheet P And a discharge tray 7 on which the printed paper P is stacked.

As is apparent from FIG.
Includes a case frame 20 and an upper cover 21 mounted on the upper side of the case frame 20. The upper cover 21 is connected to the case frame 20 so as to be openable and closable in a vertical direction about a connection portion (not shown) provided on a rear end side (a left end side in FIG. 7). A drive unit 8 containing a motor and a gear train (not shown) is inserted into one side of the case frame 20 through an opening (not shown) provided on the lower surface side of the case frame 20. The gear train of the drive unit 8 meshes with a drive gear train (not shown) provided in the main body case 2.

As shown in FIGS. 7 and 8, the paper feeding unit 3 includes a paper feeding cassette 30 which is detachably attached to the main body case 2. Paper feed cassette 30 contains paper P
Is provided. The paper P stacked on the push-up plate 31 is pressed against the paper feed roller 33 and the paper holding collar 34 by the force of the spring 32. In this state, the paper feed roller 33 rotates in the direction of the arrow in FIG. The paper is sent out from the paper feed cassette 30. A separation wall 35 is provided in front of the sheet cassette 30. The inclination of the separation wall 35 and the force of the spring 36 pressing the separation wall 35 toward the paper feed roller 33 promote the separation of the papers P from each other. As a result, the uppermost paper P in the paper supply cassette 30 is The sheet P is separated from the sheet P and sent downstream by the registration rollers 37 and 38. The movement path of the sheet P up to the sheet discharge tray 7 is indicated by a chain line PP in the figure.

The laser scanner unit 4 is mounted on a lower part of the main body case 2. A laser light generator 40 is provided inside the laser scanner unit 4.
The laser beam emitted from 0 is guided onto the photosensitive drum 50 of the process unit 5 via the polygon mirror 41, the lens 42, the mirror 43, the lens 44, and the mirror 45, as shown by arrows in FIG. The polygon mirror 41 is driven to rotate about its vertical axis in synchronization with the emission of the laser light, and the laser light is scanned in the axial direction of the photosensitive drum 50 (in the direction perpendicular to the plane of FIG. 7) with the rotation. .

The process unit 5 is housed in the main body case 2 so as to cover the upper side of the laser scanner unit 4. By opening and closing the upper cover 21, the process unit 5 is detachable from the main body case 2. A photosensitive drum 50, a charger 51, a developing device 52, and a transfer roller 53 are provided inside the case 5a of the process unit 5, respectively. The photosensitive drum 50 and the transfer roller 53 are driven to rotate about respective axes in directions indicated by arrows in the figure by a driving force supplied from the driving unit 8 (see FIG. 8). Photosensitive drum 5
Numeral 0 is constituted by covering the outer periphery of a thin cylindrical body such as an aluminum tube with a photosensitive layer. The transfer roller 53 is formed by molding a foamed resin having conductivity into a cylindrical shape. The charger 51 charges the photosensitive drum 50 by generating a corona discharge with the photosensitive drum 50. Details of the charger 51 will be described later. The outer periphery of the charged photosensitive drum 50 is irradiated with the laser beam from the laser scanner unit 4 described above, and a potential difference is generated between the irradiated portion and the non-irradiated portion to form an electrostatic latent image.

The developing device 52 supplies the toner 521 contained in the toner box 520 to the outer peripheral side of the photosensitive drum 50 via the supply roller 522 and the developing roller 523. The supplied toner 521 adheres to the photosensitive drum 50 according to the charged state of the photosensitive drum 50, whereby a visible image corresponding to the electrostatic latent image is formed on the photosensitive drum 50 (development).
Is done.

The transfer roller 53 is disposed in contact with the upper end of the photosensitive drum 50, and the sheet P is guided to these contact positions. A fixed electric field is formed between the photosensitive drum 50 and the transfer roller 53, and the electric field
0 is transferred to the sheet P. After the transfer, the residual toner on the photosensitive drum 50 is removed by the cleaning roller 54 in preparation for the next formation of the electrostatic latent image, and
At 5, the residual charge on the photosensitive drum 50 is removed. In addition,
The residual toner transferred to the cleaning roller 54 is returned to the photosensitive drum 50 at an appropriate timing (timing that does not hinder the formation of an electrostatic latent image or the like), and the returned toner is transferred via the developing roller 523 to the developing device 52. Will be collected.

The fixing unit 6 is disposed adjacent to the process unit 5 on the downstream side in the transport direction of the sheet P.
The fixing unit 6 is provided with a pair of rollers 60 and 61. The paper P to which the toner image has been transferred is
The sheet P is guided and pressed between 0 and 61, and in this state, the sheet P is heated by a heating means (not shown) such as a halogen lamp provided on one roller (for example, 60). By this pressing and heating, the toner image on the paper P is fixed. The sheet P after fixing is discharged onto the discharge tray 7 by a pair of discharge rollers 62,62. The paper discharge tray 7 is opened and closed around a connecting portion 70 provided at both ends thereof.
(See FIG. 8).

In the above-described laser beam printer 1, the paper feed cassette 30 and the process unit 5 are mounted on the main body case 2 via a predetermined mounting / removal mechanism on the assumption that the user mounts and removes the laser cassette unit. The fixing unit 6, the discharge tray 6, and the drive unit 8 are fixed to the main body case 2 by using fixing means such as bolts so that the user cannot easily disassemble the fixing unit 6, the discharge tray 6, and the drive unit 8. An assembly of the main body case 2, the laser scanner unit 4, the fixing unit 6, the paper discharge tray 6, and the drive unit 8 constitutes a main body 10 of the laser beam printer 1. The main body 10 is provided with a power supply of the image forming apparatus and a control circuit 11 for controlling a voltage or the like applied to each unit from the power supply. The position and size of the control circuit 11 are appropriately changed according to the space in the main body 10.

Next, the details of the charger 51 will be described with reference to FIGS. As illustrated in FIG. 1, the charger 51 includes a pair of holding walls 510 and 511 that are arranged to face each other in the axial direction of the photosensitive drum 50, and a pair of holding walls 510 and 511 between the holding walls 510 and 511. And a charging wire 512 erected in parallel. The charging wire 512 is made of a conductive material such as tungsten, for example, and terminals 513 and 513 are attached to both ends thereof.

The holding walls 510 and 511 are made of resin or the like, and are formed integrally with the case 5a of the process unit 5. As shown in FIGS. 2 to 4, one holding wall 510 is provided with a V-shaped notch 510 a, and a groove 510 b for receiving the charging wire 512 is provided at the bottom position.
Are formed. The charging wire 51 is provided on the holding wall 510.
A protrusion 514 protruding in a direction opposite to the direction in which the wire 2 is pulled out (the right side in FIG. 1) is provided so that the upper surface thereof substantially matches the bottom position of the notch 510a, and the protrusion 514 is aligned with the groove 510b. A groove 514a is provided.
The width of the groove 514a is set to be slightly larger than the diameter of the charging wire 512 so that the terminal 513 cannot pass through. The holding wall 510 is located at a position facing the protrusion 514.
And a restraining wall 515 is provided in parallel with. The restraining wall 515 is also formed integrally with the case 5a of the process unit 5. Clearance S between restraining wall 515 and protrusion 514
Is set to be a minimum value necessary for the terminal 513 to pass, that is, a value slightly larger than the plate thickness t of the terminal 513.

According to the above structure, the terminal 513 is inserted into the lower surface side of the protrusion 514 through the gap S, and in this state, the charging wire 513 is inserted into the grooves 514a and 510b while facing the other holding wall 511. When pulled out, the terminal 513 is locked by the protrusion 514 and the restraining wall 515 as shown, and one end of the charging wire 513 is restrained by the holding wall 510. A member separate from the holding wall 510 may be used.
4 or the charging wire 512 fixed to the restraining wall 515.
It is not necessary to prevent the terminal 513 from coming off. Terminal 51
3 is inserted into the gap S and the pulling of the charging wire 512 completes the attachment of one end of the charging wire 512, and the work is performed in a shorter time than fixing another member to the holding wall 510 or the like and pressing the terminal 513 or the like. You can finish.

As shown in FIGS. 1, 5 and 6, the other holding wall 511 has a hole 511a through which the charging wire 512 is inserted. The lower inner peripheral surface of the hole 511a is formed in a V-shape, and the charging wire 5
12 is formed. A protruding shaft 511c is provided on the outer surface side of the holding wall 511, and the protruding shaft 511c has a coil portion 51 of the torsion coil spring 516 provided thereon.
6a are fitted. The torsion coil spring 516 is made of a conductive material. The terminal 513 of the charging wire 512 inserted into the hole 511a is connected to one arm 516b of the torsion coil spring 516. Therefore, the tip of the arm 516b is formed in a hook shape. The other arm 516c of the torsion coil spring 516 is locked by a projection 511d at the lower end of the holding wall 511. One arm 516b is urged downward by the restoring force of the coil 516a, and as a result, tension is applied to the charging wire 512.

The other arm 51 of the torsion coil spring 516
6c, the electrode portion 51 exposed on the lower surface side of the protrusion 511d is provided.
6d are provided. As shown in FIG. 6, when the process unit 5 is mounted on the main body 10, the electrode portion 516d comes into contact with the spring-shaped charger contact 100 protruding from the main body 10, and as a result, the contact 100 and the charging wire 512 are twisted. It conducts through the coil spring 516 and the terminal 513.
When forming an image, the control circuit 11 of the
00, a predetermined voltage is applied to the charging wire 512.

As is apparent from FIGS. 1 to 3 and FIG. 6, the charger 51 has a pair of side walls 51 extending between the holding walls 510 and 511 in parallel with the axial direction of the photosensitive drum 50.
7, 518 are provided. The upper end of the charger 51 is entirely open toward the outer peripheral surface of the photosensitive drum 50, and a grid 519 for controlling electric charge between the charging wire 512 and the photosensitive drum 50 is attached to the opening. Supported by the side walls 517 and 518.

According to the above configuration, a part of the torsion coil spring 516 that pulls the charging wire 512 is replaced with the electrode portion 516.
Since it is used as d, the number of components is reduced as compared with the case where the electrode unit is formed using a member different from the torsion coil spring 516. Further, by simply attaching the torsion coil spring 516, the application of tension to the charging wire 512 and the electrical connection between the charging wire 512 and the electrode portion 516d are completed, so that the assembling operation can be completed in a short time.

In the above embodiment, the protrusion 514, its groove 514a, and the restraining wall 515 are a single member in which the torsion coil spring 516 also serves as the spring means and the conduction means, and the torsion coil spring 516 serves as the spring means and the conduction means. , And a spring member, and a locking member to which the terminal 513 is attached to one end side of the charging wire.

Note that the constraint wall 515 may be omitted. At least one of the holding walls 510 and 511 may be formed separately from the case 5 a so that the charger 51 can be detachably attached to the process unit 5 . The locking tool attached to one end of the strip conductive wires, may be used various shapes of members is not limited to the pin 513.

[0034]

As described in the foregoing, according to the image forming apparatus according to claim 1, and applying tension to the charging wire, the charging wire and the same member and the electrical connection between the control circuit of the image forming apparatus Therefore, the number of parts and the number of steps for assembling work can be reduced to achieve cost reduction . It Jiri attach the coil spring to the process unit it is sufficient to fix while connecting the arm of the one and the charging wire and the other arm portion to contact and possible contact position of the charging dexterity, the assembly of the charging wire This can greatly contribute to the simplification of the required configuration.

According to the charging device of the second aspect , the spring member for applying tension to the charging wire can be used as an electrode portion for connecting the charging wire to a circuit outside the charging device. The charging device suitable for the image forming apparatus according to the first aspect of the present invention can achieve cost reduction by reducing the number of components required for mounting and the number of assembling operations.

According to the image forming apparatus of claims 3 and 4 ,
One end side of the charging wire can be locked to the holding wall by using the protrusion provided on the holding wall and its groove, and after the charging wire is attached, another member is fixed to the holding wall or the like and one end of the charging wire is pressed down. Since there is no need, the number of parts required for locking one end of the charging wire can be reduced, and the number of work steps can be reduced, thereby achieving cost reduction. In particular, according to the invention of claim 4 , it is possible to more reliably prevent the locking tool from coming off by using the restraining wall, and to provide a simple and highly reliable charging wire locking structure.

[0037] According to the charging device according to claim 5, by using the projection and the groove portion provided on the retaining wall can engage the retaining wall one end of the charging wire, holding the separate member after mounting of the charging wire there is no need to press one end fixed to the charging wire on the wall or the like, to reduce the number of parts required for engaging the one end of the charging wire to achieve cost reduction, the image forming apparatus according to claim 3 or 4 A suitable charger can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view along an axial direction of a charger according to an embodiment of the present invention.

FIG. 2 is a plan view of the charger of FIG. 1 from the direction of arrow II.

FIG. 3 is a side view of the charger of FIG. 1 as seen from the direction of arrow III.

FIG. 4 is a perspective view showing a locking structure at one end of a charging wire in the charger of FIG. 1;

FIG. 5 is a side view of the charger of FIG.

FIG. 6 is a perspective view showing an attachment structure on the other end side of the charging wire in the charger of FIG. 1;

FIG. 7 is a sectional view of the laser beam printer according to the embodiment of the present invention.

FIG. 8 is an exploded perspective view of the laser beam printer according to the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser beam printer 2 ... Main body case 3 ... Paper feed unit 4 ... Laser scanner unit 5 ... Process unit 6 ... Fixing unit 7 ... Discharge tray 8 ... Drive unit 10 ... Main body 11 ... Control circuit 50 ... Photosensitive drum (image bearing) Body 51: Charger 100: Contact point for charger 510, 511: Holding wall 514: Projection 514a: Groove of projection 515: Restriction wall 516: Torsion coil spring (spring means, conduction means, spring member) 516b, 516c ... Arm of torsion coil spring 516d ... Electrode

Claims (5)

(57) [Claims] 1. A process which includes a main body having a control circuit, a cylindrical image carrier on which an image is formed on an outer periphery, and a charger for charging the image carrier, and which is detachably provided to the main body. And a unit, wherein the charger is disposed so as to face the image carrier in the axial direction.
A location and a pair of retaining walls, a charging wire which is laid in parallel to the axial direction of said image bearing member between the retaining wall, the
Locking means for locking one end of the charging wire to one holding wall
A spring unit connected to the other end of the charging wire to apply tension to the charging wire, and a contact unit for a charger provided on the main body when the process unit is mounted on the main body. In the image forming apparatus provided with a conduction unit for conducting the contact and the charging wire, the spring unit and the conduction unit are integrally provided on a single member, and are formed of a conductive material. Torsion coil spring
The torsion coil spring provided as said single member
Of the coil part on the protruding shaft provided on the outer surface side of the other holding wall
One of the torsion coil springs
Arm is connected to the other end of the charging wire, and the other arm
An image forming apparatus, wherein a portion is extended to a position where it can contact the contact . 2. A pair of holding walls facing each other, a charging wire bridged between the pair of holding walls, locking means for locking one end side of the charging wire to one of the holding walls, It is connected to the other end of the charging wire anda spring member providing a tension to the charging wire, a torsion coil spring which is configured of a material having conductivity
The coil portion of the torsion coil spring is provided as the spring member and the outer surface of the other holding wall is provided.
On the protruding shaft provided on the side
One arm of the torsion coil spring is connected to the other end of the charging wire .
And the other arm is connected to the charging wire by an external circuit.
A charging device comprising an electrode portion for connecting to the charging device. 3. A charging device is provided at one end of the charging wire.
The one holding wall is provided with a protrusion projecting in a direction opposite to a direction in which the charging wire is pulled out from the holding wall, and the locking member cannot pass through the protrusion. The image forming apparatus according to claim 1, wherein a groove having a width is provided. The method according to claim 4, wherein the processing unit, restraining wall is provided wherein by said projection and facing the one <br/> holding wall, the gap between the projection of the restricting wall and the holding wall, 4. The image forming apparatus according to claim 3, wherein a minimum value required for passing the locking member or a value slightly larger than the minimum value is set. 5. A locking device is provided at one end of the charging wire.
The one holding wall is provided with a protrusion projecting in a direction opposite to a direction in which the charging wire is pulled out from the holding wall, and the locking member cannot pass through the protrusion. The charging device according to claim 2, wherein a groove having a width is provided.