JPH04242768A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To reduce the adhesion of a toner to an non-image area on a sensitive body and prevent the waste of the toner. CONSTITUTION:A developing unit 15 is movably provided on an image forming case 18. The image forming case 18 has a driving means 50 for moving the developing unit 15, and a control means 55 for controlling the driving means 50 to press a development roller 66 onto a sensitive body 12 at the time of development and separate the roller from the sensitive body 12 at the time of non-development is provided in the device body.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is applicable to recording media such as printers, copiers, facsimile machines, etc., using an electrophotographic method (a method of recording by transferring an image formed on a photoreceptor onto a recording medium) using a laser. The present invention relates to an electrophotographic device for recording.

0002

[Prior Art] Conventionally, in this type of electrophotographic apparatus,
When the photoconductor is driven to rotate, the developing unit is biased by a spring and its developing roller is constantly pressed against the photoconductor, rotating while rubbing against each other, depositing toner on the photoconductor and creating an electrostatic latent image on its surface. There was one that had a configuration that visualized the image.

0003

[Problems to be Solved by the Invention] However, in conventional electrophotographic apparatuses of this type, the photoreceptor and the developing roller are always in contact with each other, regardless of whether the image is being developed or not. Not only that, but a small amount of toner also adheres to non-image areas that do not originally need to be visualized. A small amount of toner adhering to this non-image area also becomes a non-negligible amount as the number of prints increases, resulting in the problem of wasted toner. Therefore, an object of the present invention is to reduce the adhesion of toner to the non-image area on the photoreceptor,
The purpose is to prevent wastage of toner.

0004

[Means for Solving the Problems] In order to achieve the above object, the invention as set forth in claim 1 has a structure in which the developing unit 15 is biased by a spring to press the developing roller 66 against the photoreceptor 12, and the In an electrophotographic apparatus that applies toner to a body 12 and visualizes an electrostatic latent image on the surface thereof, the developing unit 1
a control means 55 for controlling the driving means 50 to press the developing roller 66 against the photoreceptor 12 during development and to separate it from the photoreceptor 12 during non-development; It is characterized by having the following.

[0005] Furthermore, the invention according to claim 2 is based on claim 1.
The invention described in 1 is characterized in that the developing unit 15 is movably provided on an image forming case 18, and the driving means 50 is provided on the image forming case 18.

Furthermore, the invention according to claim 3 is the invention according to claim 1, in which the driving shaft 74 on the side of the electrophotographic apparatus main body 10 and the driven shaft 67 on the side of the developing unit 15 are arranged so that their axes are misaligned. It is characterized in that it is connected by a joint mechanism such as Oldham coupling 70 that can transmit rotational force even when it is connected.

[0007]

[Function] In the invention as set forth in claims 1 and 2, the control means 55 controls the driving means 50 to move the developing unit 15, and during development, the developing roller 66 is moved between the photoreceptor 1
When not developing, the developing roller 66 is separated from the photoreceptor 12.

Furthermore, in the third aspect of the invention, rotational force is transmitted from the drive shaft 74 on the electrophotographic apparatus main body 10 side to the driven shaft 67 on the developing unit 15 side via the joint mechanism.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 4 shows a schematic configuration of a laser printer which is an embodiment of the present invention. Reference numeral 10 in the figure is the main body of the apparatus, which is placed on an optional dedicated table 11. A drum-shaped photoreceptor 12 is provided in the center of the apparatus main body 10 and rotates clockwise in the figure. Around the photoreceptor 12, a charging unit 13, an optical writing unit 14, and a developing unit 15 are arranged in order in the rotation direction.
- Arrange the transfer unit 16 and cleaning unit 17. Among them, the developing unit 15, cleaning unit 17, etc. are housed in an image forming case 18.

On the other hand, on the right side of the apparatus main body 10 in the figure,
The first paper feed cassette 19 and the second paper feed cassette 20 are removably loaded vertically. The mounting portions of these paper feed cassettes 19 and 20 are provided with paper feed means 24 having a paper feed roller 21, a registration sensor 22, a pair of registration rollers 23, and the like. On the other hand, on the opposite side of the paper feeding means 24 across the transfer unit 16, there is a transport unit 2.
5・Fixing unit 26・Switching means 27・Sheet discharge conveyance means 2
Place the 8th prizes in order. The discharge paper conveying means 28 includes:
Face-down paper discharge path 29, face-up paper discharge path 30
, a double-sided print paper discharge path 31. The face-down paper discharge path 29 includes a discharge means 32 provided on the main body 10 of the apparatus.
It also communicates with the discharged paper stack section 33 on the apparatus main body 10 via. The face-up sheet discharge path 30 includes a face-up tray 3 provided on the side of the apparatus main body 10 so as to be freely openable and closable.
Leads to 4. The double-sided print paper discharge path 31 leads to the dedicated table 11.

The dedicated table 11 is provided with a paper reversing means 38 in communication with the above-mentioned double-sided printing paper discharge path 31, and the paper reversing means 38 is also connected to the paper feeding means 24 of the apparatus main body 10 described above. A paper refeeding means 39 is provided. Further, on the right side of the dedicated table 11 in the figure, a mass paper feeder 40 is removably loaded. A paper feed roller 41 and the like are provided at the mounting portion of the mass paper feed device 40.

When the laser printer is operated, the paper feed rollers 21 and 41 are appropriately selected and driven, and paper 45 is fed from the paper feed cassettes 19 and 20 and the mass paper feed device 40. Sequentially send it out in the direction of arrow A. Then, the registration sensor 22 detects the leading edge of the paper 45, and the sheet 45 stops when it hits the registration rollers 23, thereby preventing the occurrence of skew.

On the other hand, the surface of the photoreceptor 12 is charged by the charging unit 13 as shown in FIG.
Next, an optical writing unit 14 irradiates laser light to form an electrostatic latent image on its surface, and then as it passes through a developing unit 15, the electrostatic latent image is successively visualized. Then, the above-mentioned registration roller 23 is driven by aligning the image with the resist, and the above-mentioned paper 45 that was in contact with the registration roller 23 is sent out toward the photoreceptor 12. The image on the photoreceptor 12 is then transferred onto the paper 45 in the transfer unit 16. After the transfer, the surface of the photoreceptor 12 is cleaned by a cleaning unit 17.

On the other hand, the paper 45 is sent to the fixing unit 26 by the conveyance unit 25, and the transferred image is fixed there. When discharging a large amount of paper 45,
The sheet is conveyed by the conveyance roller 46 through the face-down sheet discharge path 29 and sent out to the discharged sheet stack section 33 via the discharge means 32. If the paper 45 is thick paper such as a postcard, the switching means 27 switches the ejection direction, and the ejection roller 47 sends it out through the face-up paper ejection path 30, and it is directly placed on the open face-up tray 34 as shown by the chain line. Stuck face up. Furthermore, if it is desired to record on the back side as well, the switching means 27 similarly switches the ejection direction, the sheet is conveyed by the conveyance roller 48 through the double-sided printing sheet ejection path 31, and guided to the sheet reversing means 38. Then, it is reversed and conveyed again to the paper feeding means 24 through the paper refeeding means 39, and is recorded on the back side as well.
Or discharge it onto the face-up tray 34.

By the way, as shown in FIG. 1, the image forming case 18 has a driving means 50 fixed to the outside of the bottom 18a for driving the developing unit 15, and has a drive means 50 extending through the bottom 18a near the driving means 50. Then, a window hole 18b is formed. The driving means 50 includes a rotating lever 52 having one end attached to the movable rod 51. The rotating lever 52 is rotatably provided in the window hole 18b by a support shaft 53 that crosses the window hole 18b. The drive means 50 is electrically connected to the control means 55 . The control means 55 is appropriately disposed within the apparatus main body 10 and controls the drive means 50. On the other hand, the developing unit 15 is provided on the image forming case 18 so as to be movable in the left and right directions in the figure. One end of a compression spring 57 is pressed against the developing case 56 of the developing unit 15. The compression spring 57 presses the other end against the pressure lever 60. The pressure lever 60 is attached to the bottom 18a of the image forming case 18 with a fixing pin 61 so as to be movable in the horizontal direction in the figure, and its other end is inserted into the window hole 18b, and the other end of the rotation lever 52 is engage with. A pressure release lever 62 is located on the opposite side of the photoreceptor 12 across the pressure lever 60.
, and one end thereof is engaged with the developing case 56 of the developing unit 15 . Like the pressure lever 60, the pressure release lever 62 is located at the bottom 1 of the image forming case 18.
8a with a fixing pin 63 so as to be movable in the horizontal direction in the figure, and one end of a pressure release tension spring 64 is hooked to the other end. The other end of the pressure release tension spring 64 is connected to the image forming case 1.
Hang it on the side plate 18c of No.8.

The developing unit 15 is equipped with a developing roller 66 as shown in the figure. The developing roller 66
As shown in FIG. 2, a driven side disk 71 of an Oldham coupling (joint mechanism) 70 is fixed to one end of a roller shaft (driven shaft) 67. The Oldham coupling has a driven side disk 71, an intermediate disk 72, and a driving side disk 73.
It consists of The drive side disk 73 is fixed to the drive shaft 74 on the side of the device main body 10, and its linear protrusion 73a is engaged with the linear groove 72a on one side of the intermediate disk 72. Then, the straight groove 72b on the other side of the intermediate disk 72 and the driven side disk 71
The linear protrusion 71a is engaged to connect the apparatus main body 10 side and the developing unit 15 side.

When the device main body 10 is driven and the drive shaft 74 is rotated in the direction of the arrow, the drive-side disk 73 rotates, and the rotation is caused by the linear protrusion 73a and the linear groove 7.
The developing unit 15 is rotated by being transmitted to the intermediate disc 72 through engagement with the linear groove 72b and the linear protrusion 71a, and then to the driven disc 71 through engagement with the linear groove 72b and the linear protrusion 71a. When not developing, the control means 55 stops the operation of the driving means 50, and the developing unit 15 is moved by the tensile force of the pressure release tension spring 64 and stopped against a stopper (not shown), as shown in FIG. Then, the developing roller 66 is separated from the photoreceptor 12. At the same time, the compression spring 57 is extended to a substantially free length state, the pressure lever 60 is moved, the rotation lever 52 is rotated, and the movable rod 51 is pulled out.

On the other hand, during development, the control means 55 operates the drive means 50 to draw in the movable rod 51. Then, the rotary lever 52 is rotated clockwise in the figure to the state shown in FIG. 3, and the pressure lever 60 is moved. And the compression spring 57
The developing unit 15 is moved against the pressure release tension spring 64 via the compression spring 57, and the developing roller 66 is pressed against the photoreceptor 12 by the biasing force of the compression spring 57. As a result, the development area 77 on the photoreceptor 12 is developed.

Then, the image area 77 of the photoreceptor 12
When the visualization of the photoreceptor 1 is completed, the control means 55 stops the operation of the drive means 50 again, and as described above, the photoreceptor 1
The developing unit 15 is separated from the photoreceptor 12, and the developing roller 66 is brought into a non-contact state with respect to the photoreceptor 12.

[0021] In the above-described embodiment, the device main body 10
The driving shaft 74 on the side and the driven shaft 67 on the developing unit 15 side are connected via a joint mechanism using an Oldham coupling 70. However, the present invention may be configured such that the drive shaft on the apparatus main body side and the driven shaft on the developing unit side are connected via another joint mechanism such as a bellows.

[0022]

From the above, according to the electrophotographic apparatus according to the present invention, the control means controls the driving means to move the developing unit, and during development, the developing roller is pressed against the photoreceptor. Since the developing roller is separated from the photoreceptor during non-development, the amount of toner adhering to the non-image area on the photoreceptor can be reduced, and wasteful use of toner can be prevented.

Furthermore, since the developing roller is separated from the photoreceptor during non-development, even if the photoreceptor is not driven for a long time, the surface of the developing roller will not be deformed, and the image quality due to deformation will be reduced. can prevent a decline in

Furthermore, according to the electrophotographic apparatus according to the third aspect, it is possible to allow misalignment between the drive shaft on the apparatus main body side and the non-drive shaft on the developing unit side, and to transmit rotational force without difficulty. can.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram around a developing unit in an electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is an external perspective view of a part thereof.

FIG. 3 is a state diagram when the developing roller of the developing unit visualizes the image area of the photoreceptor.

FIG. 4 is an overall schematic configuration diagram of the internal mechanism of the electrophotographic apparatus.

[Explanation of symbols]

10　Device body 12 Photoreceptor 15 Developing unit 18 Imaging case 50 Driving means 55 Control means 66 Developing roller 67 Roller axis (driven axis) 74 Drive shaft

Claims (3)

[Claims] Claim 1: The developing unit is biased by a spring and the developing roller is
In an electrophotographic apparatus that presses a photoreceptor against a photoreceptor, toner adheres to the photoreceptor, and visualizes an electrostatic latent image on the surface of the photoreceptor, a driving means for moving the developing unit is provided, and the driving means 1. An electrophotographic apparatus, comprising: a control means that presses the developing roller against the photoreceptor during development and moves it away from the photoreceptor during non-development. 2. The electrophotographic apparatus according to claim 1, wherein the developing unit is movably provided on an image forming case, and the driving means is provided on the image forming case. 3. The electrophotographic apparatus according to claim 1, wherein the drive shaft on the electrophotographic apparatus main body side and the driven shaft on the developing unit side are connected by a joint mechanism that can transmit rotational force even if there is an axial misalignment.
The electrophotographic device described in .