JP2009025429A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of suppressing heat generation by power saving and also achieving cost reduction and low noise. <P>SOLUTION: The image forming apparatus is constituted by interposing electromagnetic clutches CL in driving transmission paths from motors M2 to M4 that are driving sources to developing devices 4a to 4d, a feed roller 16, a retard roller 17, a resist roller 19, a fixing device 22 and paper ejection rollers 23 and 24 (rotating member of every kind of process equipment), wherein the electromagnetic clutch CL is a closed type one (electromagnetic spring clutch of a reverse action type). Since the electromagnetic clutch CL is the closed type one, the electromagnetic clutch CL is not energized in the midst of image forming operation, thereby suppressing the heat generation by the power saving and also achieving the cost reduction and the low noise. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus in which an electromagnetic clutch is interposed in a drive transmission path from a motor as a drive source to a rotating member of various process devices.

  In an image forming apparatus such as a copying machine or a printer that employs an electrophotographic system, an electromagnetic clutch is provided in a drive transmission path from a motor as a driving source to various process devices such as a photosensitive drum and a developing device. The drive transmission from the motor to various process devices is turned ON / OFF by the motor, but the open type is used exclusively for the electromagnetic clutch. Here, the open-type electromagnetic clutch connects the drive (ON) when energization is turned on, and cuts off the drive transmission (OFF) when the energization is turned off.

Patent Document 1 discloses a forward / reverse rotation device in which one of an electromagnetic clutch connecting a main input gear and an output shaft, an electromagnetic clutch connecting a sub input gear and an intermediate shaft is a closed type, and the other is an open type. Proposed.
Japanese Patent Laid-Open No. 2-256943

  The open type electromagnetic clutch used in the past has a simple structure and is advantageous in terms of cost. In addition, since it can cope with both forward and reverse rotations, it has a high degree of freedom in design and stable response. However, especially in a high-speed tandem printer, etc., since the drive is almost connected, a current of about 3 W to 4 W always flows through the electromagnetic clutch, and the heat generation of the coil cannot be ignored. It becomes. When the electromagnetic clutch generates heat in this way, resinization of the shaft and the surrounding housing for the purpose of cost reduction and component integration may be hindered.

  In particular, since a large number of electromagnetic clutches are used in a tandem type full-color image forming apparatus, there is a problem in that the power supply capacity is increased because a large current is required when drive connection is required at the same time.

  Furthermore, in open type electromagnetic clutches, the iron plates collide during drive connection, resulting in a loud noise. There is also a problem in that fine iron powder adheres to the electric substrate and these operations are impaired.

  The present invention has been made in view of the above problems, and an object thereof is to provide an image forming apparatus capable of suppressing heat generation by power saving and realizing cost reduction and low noise.

  In order to achieve the above object, an invention according to claim 1 is an image forming apparatus in which an electromagnetic clutch is provided in a drive transmission path from a motor as a driving source to a rotating member of various process devices. It is a closed type.

  According to a second aspect of the present invention, in the first aspect of the invention, the close type electromagnetic clutch is constituted by a reverse action type electromagnetic spring clutch.

  A third aspect of the invention is characterized in that, in the first or second aspect of the invention, a plurality of image carriers and developing devices are arranged in tandem as the process equipment.

  According to the first aspect of the present invention, since the electromagnetic clutch is a closed type, the electromagnetic clutch is not energized during the image forming operation. Therefore, heat generation is suppressed by power saving, and cost reduction and low noise are realized. Is done.

  According to the second aspect of the present invention, since the closed type electromagnetic clutch is constituted by the reverse operation type electromagnetic spring clutch, it is only necessary to pass a low current sufficient to open the spring to the electromagnetic spring clutch. As a result, heat generation can be kept low. In addition, the electromagnetic spring clutch achieves low noise because the drive is connected while winding the spring around the shaft, and since the half-clutch state between the shaft and the spring is instantaneous, no wear powder is generated. It is possible to effectively prevent the generation of sound and wear powder by making the resin.

  According to the third aspect of the present invention, power saving, cost reduction, low noise, and cost reduction can be effectively realized in a tandem type image forming apparatus in which many electromagnetic clutches are used.

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

  FIG. 1 is a front sectional view of an image forming apparatus according to the present invention, and FIG. 2 is a block diagram showing a configuration of a drive system of the image forming apparatus.

  The image forming apparatus shown in FIG. 1 is a tandem type color image forming apparatus, and a magenta image forming unit 1M, a cyan image forming unit 1C, a yellow image forming unit 1Y, and a black image forming unit are provided in the center of the main body 100. Units 1BK are arranged in a line at regular intervals.

  Each of the image forming units 1M, 1C, 1Y, and 1BK is provided with photosensitive drums 2a, 2b, 2c, and 2d as image carriers, and a charger 3a is provided around each of the photosensitive drums 2a to 2d. , 3b, 3c, 3d, developing devices 4a, 4b, 4c, 4d, transfer rollers 5a, 5b, 5c, 5d as primary transfer means, and cleaning devices 6a, 6b, 6c, 6d, respectively.

  Here, the photosensitive trams 2a to 2d are drum-shaped photosensitive members, and are driven to rotate at a predetermined process speed in the direction indicated by the arrow (clockwise) by the motor M1 shown in FIG. The chargers 3a to 3d uniformly charge the surfaces of the photosensitive drums 2a to 2d to a predetermined potential by a charging bias applied from a charging bias power source (not shown).

  Further, the developing units 4a to 4d contain magenta (M) toner, cyan (C) toner, yellow (Y) toner, and black (BK) toner, respectively, and are formed on the photosensitive drums 2a to 2d. Each color latent image is attached to each electrostatic latent image to visualize each electrostatic latent image as a toner image of each color, and these are driven by a motor M2 shown in FIG.

  The transfer rollers 5a to 5d as primary transfer means are disposed so as to be in contact with the photosensitive drums 2a to 2d via the intermediate transfer belt 7 in each primary transfer portion. Here, the intermediate transfer belt 7 is stretched between the secondary transfer counter roller 8 and the tension roller 9 and is disposed on the upper surface side of each of the photosensitive drums 2a to 2d. The roller 8 is disposed so as to be in contact with the secondary transfer roller 10 via the intermediate transfer belt 7 in the secondary transfer portion. A belt cleaning device 11 is provided in the vicinity of the tension roller 9. As a material for the intermediate transfer belt 7, for example, a dielectric resin such as polycarbonate, polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), or the like is selected.

  By the way, above the image forming units 1M, 1C, 1Y, and 1BK in the apparatus main body 100, toner containers 12a, 12b, 12c, and 12d for supplying toner to the developing units 4a to 4d are arranged in a line. It is installed.

  In addition, a laser scanner unit (LSU) 13 is disposed below the image forming units 1M, 1C, 1Y, and 1BK in the apparatus main body 100, and a paper feed cassette 14 is detachably attached to the bottom of the main body 100 below the image forming units. is set up. A plurality of recording materials (sheets) (not shown) are stacked and accommodated in the paper feed cassette 14, and in the vicinity of the paper feed cassette 14, a pickup roller for taking out the recording materials one by one from the paper feed cassette 14 15 and a feed roller 16 and a retard roller 17 for feeding the taken recording material to the conveyance path L are provided.

  The conveyance path L extending in the vertical direction on the side of the apparatus main body 100 includes a conveyance roller 18 that conveys the recording material, and the secondary transfer counter roller 8 at a predetermined timing after the recording material is temporarily held. There is provided a registration roller 19 that supplies a secondary transfer portion that is a contact portion with the secondary transfer roller 10. Next to the conveyance path L, another conveyance path L ′ used for forming an image on both sides of the recording material is formed, and a plurality of conveyance rollers 21 are appropriately provided in the conveyance path L ′. Are provided at regular intervals.

Thus, the feed roller 16, the retard roller 17 and the registration roller 19 are rotationally driven by the motor M3 shown in FIG.
By the way, the transport path L arranged in the vertical direction on one side of the apparatus main body 100 extends to the paper discharge tray 21 provided on the upper surface of the apparatus main body 100, and the fixing device 22 and a plurality of them are in the middle. The paper discharge rollers 23 and 24 are provided, and the fixing device 22 and the paper discharge rollers 23 and 24 are driven by a motor M4 shown in FIG.

  Next, an image forming operation by the color image forming apparatus having the above configuration will be described.

  When an image formation start signal is issued, the photosensitive drums 2a to 2d are driven to rotate at a predetermined process speed in the direction of the arrow in FIG. 1 (clockwise) in each of the image forming units 1M, 1C, 1Y, and 1BK. The drums 2a to 2d are uniformly charged by the primary chargers 3a to 3d. The laser scanner unit 13 emits a laser beam modulated by a color image signal for each color, irradiates the surface of each photosensitive drum 2a to 2d with the laser beam, and each color is applied to each photosensitive drum 2a to 2d. An electrostatic latent image corresponding to the color image signal is formed.

  First, magenta toner is attached to the electrostatic latent image formed on the photosensitive drum 2a of the magenta image forming unit 1M by the developing device 4a to which a developing bias having the same polarity as the charging polarity of the photosensitive drum 2a is applied. The electrostatic latent image is visualized as a magenta toner image. This magenta toner image is transferred to the arrow shown in FIG. 1 by the action of the transfer roller 5a to which a primary transfer bias having a polarity opposite to that of the toner is applied at the primary transfer portion (transfer nip portion) between the photosensitive drum 2a and the transfer roller 5a. Primary transfer is performed on the intermediate transfer belt 7 which is rotationally driven in the direction.

  The intermediate transfer belt 7 on which the magenta toner image has been primarily transferred as described above moves to the next cyan image forming unit 1C. In the cyan image forming unit 1C as well, the cyan toner image formed on the photosensitive drum 2b is transferred to the magenta toner image on the intermediate transfer belt 7 in the primary transfer portion in the same manner as described above.

  Similarly, yellow and black toners respectively formed on the photosensitive drums 2c and 2d of the yellow and black image forming units 1Y and 1BK on the magenta and cyan toner images superimposed and transferred on the intermediate transfer belt 7, respectively. The images are sequentially superimposed at each primary transfer portion, and a full-color toner image is formed on the intermediate transfer belt 7. The transfer residual toner that is not transferred onto the intermediate transfer belt 7 and remains on the photosensitive drums 2a to 2d is removed by the cleaning devices 6a to 6d, and the photosensitive drums 2a to 2d are prepared for the next image formation. .

  Then, the pickup from the paper feed cassette 14 is performed in accordance with the timing at which the front end of the full color toner image on the intermediate transfer belt 7 reaches the secondary transfer portion (transfer nip portion) between the secondary transfer counter roller 8 and the secondary transfer roller 10. The recording material fed to the conveyance path L by the roller 15, the feed roller 16 and the retard roller 17 is conveyed to the secondary transfer portion by the registration roller 19. Then, a full-color toner image is collectively transferred from the intermediate transfer belt 7 to the recording material conveyed to the secondary transfer portion by the secondary transfer roller 10 to which a secondary transfer bias having a polarity opposite to that of the toner is applied. The

  Thus, the recording material onto which the full-color toner image has been transferred is conveyed to the fixing device 22 where the full-color toner image is heated and pressurized to be thermally fixed on the surface of the transfer material, and the toner image is fixed. The transfer material is discharged onto the discharge tray 21 by the discharge rollers 23 and 24, and a series of image forming operations is completed. The transfer residual toner that is not transferred onto the recording material and remains on the intermediate transfer belt 7 is removed by the belt cleaning device 11, and the intermediate transfer belt 7 is prepared for the next image formation.

  As shown in FIG. 2, an electromagnetic clutch CL is interposed in the drive transmission path from the motor M2 to the developing devices 4a to 4d, and the drive transmission from the motor M3 to the feed roller 16, the retard roller 17, and the registration roller 19 is performed. A clutch CL is interposed in the path, and an electromagnetic clutch CL is interposed in the drive transmission path from the motor M4 to the fixing device 22 and the paper discharge rollers 23 and 24. The electromagnetic clutch CL is an open type. Things are used.

  In this embodiment, a reverse operation type electromagnetic spring clutch is used as the open type electromagnetic clutch CL. In this reverse operation type electromagnetic spring clutch, when energization is cut off (OFF), the spring is wound around the shaft and the drive transmission is turned on, and when energized, the spring is wound around the shaft. The drive transmission is turned off.

  Thus, in the present embodiment, since the reverse operation type electromagnetic spring clutch which is a closed type is used as the electromagnetic clutch CL, the electromagnetic clutch CL is not energized during the image forming operation, and therefore heat is generated by power saving. The cost is reduced and the noise is reduced. In particular, in a tandem type image forming apparatus in which a plurality of photosensitive drums 2a to 2d and developing devices 4a to 4d are arranged in parallel as in the full-color image forming apparatus according to the present embodiment, many electromagnetic clutches CL are provided. A great effect can be obtained.

  Further, as a result of using a reverse operation type electromagnetic spring clutch for the electromagnetic clutch CL, it is only necessary to pass a low current sufficient to open the spring to the electromagnetic spring clutch, so that power can be saved and heat generation can be kept low. . The electromagnetic spring clutch is connected to the drive while the spring is wound around the shaft, so that low noise is realized, and since the half-clutch state between the shaft and the spring is instantaneous, no wear powder is generated. It is possible to effectively prevent the generation of sound and wear powder by making the resin.

1 is a front sectional view of an image forming apparatus (color image forming apparatus) according to the present invention. 1 is a block diagram illustrating a configuration of a drive system of an image forming apparatus (color image forming apparatus) according to the present invention.

Explanation of symbols

1M Magenta image forming unit 1C Cyan image forming unit 1Y Yellow image forming unit 1BK Black image forming unit 2a to 2d Photosensitive drum (image carrier)
3a to 3d Primary charger 4a to 4d Developer 5a to 5d Transfer roller 6a to 6d Cleaning device 7 Intermediate transfer belt 8 Secondary transfer counter roller 9 Tension roller 10 Secondary transfer roller 11 Belt cleaning device 12a to 12d Toner container 13 Laser Scanner unit (LSU)
DESCRIPTION OF SYMBOLS 14 Paper feed cassette 15 Pickup roller 16 Feed roller 17 Retard roller 18 Conveyance roller 19 Registration roller 20 Conveyance roller 21 Discharge tray 22 Fixing device 23, 24 Discharge roller CL Electromagnetic clutch L, L 'Conveyance path M1-M4 Motor

Claims (3)

In an image forming apparatus comprising an electromagnetic clutch in a drive transmission path from a motor as a drive source to a rotating member of various process devices,
An image forming apparatus, wherein the electromagnetic clutch is a closed type.   2. The image forming apparatus according to claim 1, wherein the close type electromagnetic clutch is constituted by a reverse action type electromagnetic spring clutch. The image forming apparatus according to claim 1, wherein a plurality of image carriers and developing devices are arranged in tandem as the process equipment.

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