JP2010280479A - Driving device for image forming device and image forming device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem with an image forming device having a DC motor as a drive source for driving a conveying roller needed to be intermittently driven for forming an image on a recording medium. <P>SOLUTION: The driving device includes: a resist roller 7; the DC motor 12; a drive member 13; and drive members 15 and 16 for creating play 14. The play 14, required for an acceleration section for the DC motor 12 to be driven and reach the target number of rotation, is provided and after the DC motor 12 reaches the target number of rotation, the resist roller 7 is driven. The play, required for acceleration of the DC motor, is expressed by δd[rad]=(Z1/Z2)×Nr×2π (Z1: number of gear teeth of the DC motor; Z2: number of gear teeth provided with the play; Nr: number of times in rotations before the motor reaches the target number of rotation, wherein (Z1/Z2)×Nr<1). When a play width is in a target value, a driving start point of the conveying roller is delayed to intermittently drive the conveying roller without using a clutch even when the DC motor is used as the drive source. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, and a fax machine, and more particularly to a color copying machine including a plurality of photosensitive members, a driving device for an image forming apparatus such as a color printer, and an image forming apparatus using the same. .

  In a conventional image forming apparatus, a conveyance roller that requires timing and intermittent driving to form an image on a recording medium, such as a registration roller for conveying the recording medium, is a driving source. A configuration of a DC motor and a clutch necessary for intermittent driving and a configuration of using a stepping motor as a driving source have been adopted.

  In such a driving apparatus for an image forming apparatus, for example, in Patent Document 1, a paper feed gear, a boss part, a base part, and a tubular part are integrally formed of resin, a spring is inserted into the base part, and the tubular part is further inserted. The transmission sleeve is inserted and inserted, and is constituted by a spring clutch built in the paper feed roller. A backlash in the rotational direction is provided between the transmission sleeve and the holding sleeve. And by incorporating the spring clutch, the required amount of rubber of the rubber roller can be reduced, and by directly attaching the boss and tubular parts molded with resin to the frame, bearings and countermeasures against static electricity can be omitted. In addition, the spring clutch can be protected from dust. However, since a spring clutch is also used, the number of parts increases and the cost increases.

  In Japanese Patent Laid-Open No. 2004-260688, the transfer sheet conveying performance of the sheet feeding drive unit is stabilized by using an independent DC motor as a driving source without using a drive shut-off mechanism such as an electromagnetic clutch. In order to provide an image forming apparatus and an image forming apparatus including the same, in a DC motor as a driving source and a paper feeding device, the conveying means is temporarily stopped when the leading edge of the transfer paper reaches a pair of registration rollers provided in the conveying path. A brake mechanism for forming a slack is provided. However, the provision of the brake mechanism increases the number of parts and increases the cost.

  That is, when the drive source is a DC motor, the problem of durability of the clutch and the number of parts increase, and when the drive source is a stepping motor, there is a problem that power consumption increases.

  Therefore, in the present invention, in order to solve the above-described problems in an image forming apparatus that uses a DC motor as a drive source, measures the timing for forming an image on a recording medium, and drives a conveyance roller that requires intermittent driving. It is an object to enable acceleration of the DC motor by improving the drive train from the DC motor to driving the conveyance roller.

  The drive device for an image forming apparatus according to the first aspect of the present invention includes a transport roller that uses a DC motor as a drive source and requires a timing drive and intermittent drive in order to form an image on a recording medium. In the driving device for an image forming apparatus to be driven, a predetermined amount of play required for the DC motor to accelerate is provided in a drive train from the DC motor to driving the transport roller. .

  According to a second aspect of the present invention, in the drive device for an image forming apparatus according to the first aspect, the play is the highest number of rotations in the drive train until the drive is transmitted from the DC motor as the drive source to the transport roller. Is provided in a drive transmission member having a small diameter.

  According to a third aspect of the present invention, in the driving device for the image forming apparatus according to the first and second aspects, a biasing member is provided on the driving member for providing the play.

  According to a fourth aspect of the present invention, in the drive device for an image forming apparatus according to the first and second aspects, the DC motor is reversely rotated after the recording medium is conveyed.

  According to a fifth aspect of the present invention, in the drive device for an image forming apparatus according to any one of the first to fourth aspects, a buffer member is provided on the drive member provided with the play.

  An image forming apparatus according to a sixth aspect includes the drive device according to any one of the first to fifth aspects.

  According to the present invention, even if a DC motor is used as a driving source, intermittent driving force can be transmitted to the transport roller without using a clutch.

1 is a schematic configuration diagram showing a printer that can be an object of the present invention. Schematic diagram for driving the registration roller The figure which shows the drive structure of the registration roller seen from the image forming apparatus inside A perspective view and a sectional view provided with a biasing member for always providing play when the DC motor is activated The figure which shows the positional relationship of the upstream drive member and downstream drive member from starting to stop of DC motor 14, and reverse rotation The figure which shows the example which provided the shock absorbing material in the contact surface of the upstream drive member and the downstream drive member The figure explaining the play of the predetermined amount required in order for a DC motor to accelerate The figure explaining the play of the predetermined amount required in order for a DC motor to accelerate The figure explaining the play of the predetermined amount required in order for a DC motor to accelerate

  The present invention provides a recording medium using a DC motor as a drive source by providing a predetermined amount of play (backlash) necessary for the DC motor to accelerate in the drive train from the DC motor to driving the conveyance roller. In an image forming apparatus that drives a conveyance roller that needs to be driven intermittently to form an image, intermittent drive force is transmitted to the conveyance roller without using a clutch even if a DC motor is used as the drive source. To do.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the illustrated embodiment, and can be applied to various apparatuses that perform image formation.

Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment of an electrophotographic printer (hereinafter simply referred to as a printer) will be described.
First, the basic configuration of the printer will be described. FIG. 1 is a schematic configuration diagram showing a printer that can be an object of the present invention. In the figure, a printer main body is provided with a process cartridge 1. The process cartridge 1 has a developing device 2 including a photoconductor described later. The process cartridge 1 and the developing device 2 use an image forming substance to form an image, but are replaced when the lifetime is reached.

  In the figure, reference numeral 3 denotes an optical scanning device. The optical scanning device 3 optically scans each photosensitive member in the process cartridge 1 with a laser beam emitted based on a control signal of an optical writing circuit. By this optical scanning, an electrostatic latent image is formed on the photoreceptor. The optical scanning device 3 irradiates the photosensitive member through a plurality of optical lenses and mirrors while deflecting a laser beam emitted from a laser oscillator by a polygon mirror rotated by a motor.

  In the lower part of the figure, paper storage means having a paper storage cassette 4 and a paper feed roller 5 incorporated therein are arranged. The paper storage cassette 4 stores a plurality of recording media P in a stacked manner, and a paper feed roller 5 is brought into contact with each uppermost recording medium P. When the paper feeding roller 5 is rotated counterclockwise in the figure by the driving means, the uppermost recording medium P is sent out toward the paper feeding path 6.

  A registration roller pair 7 is disposed near the paper feed path 6. The registration roller pair 7 rotates both rollers so as to sandwich the recording medium P, but temporarily stops rotating immediately after sandwiching the recording medium P. Then, the recording medium P is sent out toward the developing device 2 at an appropriate timing, and the toner image formed on the photoreceptor 8 is transferred onto the recording medium P. This toner image is sent to the fixing device 9 together with the recording medium P and fixed on the surface of the recording medium P. The recording medium P on which image fixing processing has been performed in the fixing device 9 exits the fixing device 9 and then passes through a pair of paper discharge rollers 10 and is placed on a stack portion 11 provided on the upper surface of the printer housing. Stacked.

FIG. 2 is a schematic diagram for driving the registration roller 7. A drive member 13 that transmits drive to the DC motor 12 that is a drive source, an upstream drive member 15 for creating play 14, and a downstream drive member 16 are provided. When the DC motor 12 starts to be driven, the drive member 13 and the upstream drive member 15 are driven via a gear 17 coaxial with the DC motor. In this apparatus, at the time of driving transmission, the registration roller 7 must reach the target rotational speed, but the DC motor 12 requires an acceleration section until the target rotational speed is reached. In FIG. 2, by providing the necessary play 14 in the acceleration section of the DC motor 12, the registration roller 7 is driven after the DC motor 12 reaches the target rotational speed.

  FIG. 3 shows a driving configuration of the registration roller 7 as viewed from the inside of the image forming apparatus. The number of rotations on the drive member shaft that drives the registration roller 7 is the number of rotations of the DC motor and the number of teeth constituting the drive train (here, the DC motor shaft upper gear 17 (number of teeth Z17), the drive member 13 (number of teeth). Z13) and the upstream drive member 15 (the number of teeth Z15)). In FIG. 3, the play 14 is provided on the registration roller shaft having the smallest rotational speed. FIG. 4 shows a perspective view and a cross-sectional view including an urging member 18 (an elastic body, preferably a spring or rubber) for always providing the play 14 when the DC motor 14 is activated.

  FIG. 5 shows the positional relationship between the upstream drive member and the downstream drive member from the start, stop, and reverse rotation of the DC motor 14. There is a play 14 before the DC motor 14 is activated, and the play is absorbed in the acceleration section of the DC motor. When the DC motor 14 comes into contact, the downstream drive member reaches the target rotational speed and is driven by the connected registration rollers. To communicate. After the registration roller finishes conveying the recording medium, the DC motor temporarily stops and rotates backward by the play 14. (The motor torque at the time of reverse rotation is preferably equal to or less than the torque required for driving the registration roller or the like.) Thus, the play 14 is always secured when the DC motor is started.

  In FIG. 6, a cushioning material 19 is provided on the contact surface between the upstream drive member 15 and the downstream drive member 16.

A predetermined amount of play required for the DC motor to accelerate will be described with reference to FIGS.
A predetermined amount of play δd [rad] required for the DC motor to accelerate can be expressed by the following equation. That is,
(Equation 1)
δd [rad] = (Z1 / Z2) × Nr × 2π
Here, Z1 is the number of teeth of the DC motor gear, Z2 is the number of teeth of the gear (upstream side) providing play, and Nr is the number of times the motor rotates until it reaches the target number of rotations. However, the condition is (Z1 / Z2) × Nr <1. A graph of this is shown in FIG.

  When the inventors of the present application conducted an experiment, by providing the play width obtained by Equation 1, the transport roller can be driven when the target number of rotations is reached, as shown in FIG. It can be seen that it varies depending on the value. The upper curve in the figure is the rising curve of the DC motor when the desired play width is reached, and the lower curve is the rising curve of the DC motor when the play width is insufficient, and the play width is the target value. It can be seen that the driving start point of the conveying roller is delayed, and therefore, even if a DC motor is used as a driving source, a mode in which the conveying roller is intermittently driven without using a clutch can be realized.

  In the above-described play, the play is provided in the drive transmission member having the smallest number of rotations in the drive train from the drive motor to the drive roller. As a result, the impact can be reduced when the drive is connected, and the recording medium can be reliably conveyed. Further, if the urging member is provided in the drive member for providing play, the above-described play can always be provided when the DC motor is activated. In addition, by configuring the DC motor to rotate in reverse after the recording medium has been transported, play can always be provided when the DC motor is activated. Further, by providing a buffer member on the drive member provided with play, the impact can be reduced when the drive is connected, and the recording medium can be reliably conveyed.

  The image forming apparatus according to the present invention can also be used in any one of a copying machine, a facsimile machine, a printer, a printing machine, and an ink jet recording apparatus, or a multifunction machine that combines at least two functions thereof.

1: Process cartridge 2: Developing device 3: Optical scanning device 4: Paper storage cassette 5: Paper feed roller P: Recording medium 6: Paper feed path 7: Registration roller pair 8: Photoconductor 9: Fixing device 10: Paper discharge Roller pair 11: Stack portion 12: DC motor 13: Drive member 14: Play 15, 16: Drive member 17: Gear 18: Biasing member 19: Buffer material

JP 05-097259 A Japanese Patent Laid-Open No. 2008-044683

Claims (6)

In a drive device for an image forming apparatus that uses a DC motor as a drive source and drives a conveyance roller that needs to be intermittently driven in order to form an image on a recording medium.
A drive device for an image forming apparatus, wherein a predetermined amount of play necessary for the DC motor to accelerate is provided in a drive train from the DC motor to driving the transport roller. The drive device for an image forming apparatus according to claim 1.
The drive device for an image forming apparatus, wherein the play is provided on a drive transmission member having the smallest number of rotations in the drive train until the drive is transmitted from the DC motor as the drive source to the transport roller. The drive device for an image forming apparatus according to claim 1 or 2,
A driving device for an image forming apparatus, wherein a biasing member is provided on the driving member for providing play. The drive device for an image forming apparatus according to claim 1 or 2,
A drive device for an image forming apparatus, wherein the DC motor is reversely rotated after the recording medium is conveyed. The drive device for an image forming apparatus according to any one of claims 1 to 4,
A drive device for an image forming apparatus, wherein a buffer member is provided on the drive member provided with the play. An image forming apparatus comprising the driving device according to claim 1.