JPH11247875A - Power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the fluctuation in the rotational speed or a play of a drive shaft by forming a taper to be reduced in the inserting direction of the drive shaft in a connection hole in a transmission member, and forming a taper to be agreed with the connection hole on a tip part of the drive shaft. SOLUTION: Both side surfaces opposite to each other are inclined in a symmetric manner on a tip part 13 of a drive shaft 1 to form a taper with the tip side slender. The diameter (h) of the tip at the tip part 13 is as large as the diameter of a connection hole 23 on a face surface side where the drive shaft 1 of a pulley 5 is not inserted. A recessed cylindrical screw hole 17 is formed at the center of the tip part 13, and a screw groove is formed inside a cylinder so as to receive a screw 15. The connection hole 23 connecting the tip part 13 of the drive shaft 1 to the center of a pulley 5 is formed, and a taper to be agreed with the tip part 13 is formed. The pulley 5 is rotated through a belt by a drive motor, and the drive shaft 1 to be coupled therewith is rotated. Because the drive shaft 1 and the connection hole 23 are fitted to each other by the taper, and eccentricity and looseness are less prone to generate, and the fluctuation in the rotational speed and a play of the drive shaft 1 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a laser printer,
The present invention relates to a power transmission device in an image forming apparatus such as a facsimile and a copying machine.

[0002]

2. Description of the Related Art In general, for example, when a drive shaft such as a photosensitive drum and a power transmission member such as a pulley are fastened, a connecting hole of the pulley is formed in a D-shape, and a leading end of the drive shaft fitted with the connecting hole is connected. Similarly, they were D-shaped, fitted together, and then stopped by E-rings. In addition, after fitting the drive shaft and the pulley, the pin and the key (wedge) are inserted into the gap between the outer peripheral surface of the drive shaft and the inner peripheral surface of the hole of the pulley to stop the drive shaft.

[0003]

However, in the configuration in which the photosensitive drum is stopped by the E-ring in the form of a D-shape, the end of the drive shaft of the photosensitive drum is eccentric due to the D-shape. However, there is a problem that the rotation speed fluctuates. In addition, the same problem occurs in the method of inserting a pin or a key, and furthermore, with this configuration, the coupling between the drive shaft of the photosensitive drum and the member between the pulley is apt to be loosened, so that there is a backlash. There is also a problem that a problem occurs. If such problems as fluctuations in the rotation speed of the photosensitive drum and rattling occur, it becomes difficult to form a stable image when the toner image formed on the photosensitive drum is transferred to paper.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power transmission device that prevents fluctuations and rattling of the rotation speed of a drive shaft.

[0005]

According to a first aspect of the present invention, there is provided a transmission member for transmitting an output from a drive motor provided in an image forming apparatus, and a transmission member which fits into a connection hole of the transmission member and rotates. A drive shaft for transmitting a driving force, wherein the connection hole is formed with a taper that narrows along an insertion direction of the drive shaft, and a tip end of the drive shaft is formed in the connection hole. It is characterized in that a matching taper is formed.

According to the first aspect of the present invention, the power transmission device includes a transmission member having a connecting hole tapered.
The drive shaft is formed by connecting a drive shaft having a tapered end portion that matches the connection hole. The transmission member rotates by the output from the drive motor, and accordingly, the drive shaft connected to the transmission member rotates. Since the drive shaft and the connection hole are tapered and fitted to each other, eccentricity and loosening of the fastening portion are unlikely to occur, so that fluctuations in the rotational speed of the drive shaft and rattling are prevented.

According to a second aspect of the present invention, in the first aspect of the present invention, a screw hole is formed in a tip portion of the drive shaft, and the transmission member and the drive shaft are connected by a screw. It is characterized by being fastened.

According to the second aspect of the present invention, the drive shaft is fastened to the transmission member only by tightening the screw into the screw hole formed at the tip of the drive shaft. And maintenance is easy. In addition, by fastening the drive shaft to the transmission member with a screw, the fastening portion is strengthened and rattling is more reliably prevented.

According to a third aspect of the present invention, in the second aspect of the present invention, the transmission member includes a protrusion protruding from a head side of the screw, and when the screw is loosened, the screw is released. The head is provided with a protruding portion that moves and abuts.

According to the third aspect of the present invention, the transmission member has a projection which comes into contact with the head of the screw when the screw is loosened. When the transmission member is detached from the drive shaft, the screw is loosened to some extent. The screw head moves and the screw head comes into contact with the protrusion. When the screw head is further loosened while the screw head is in contact with the projection, the screw head pushes the projection, and the transmission member is pushed in the direction away from the drive shaft axis. Easily comes off the drive shaft. Therefore,
Removal of the transmission member is simplified.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 7 shows a copying machine (image forming apparatus) 100 to which the power transmission device according to the present embodiment is applied. The copying machine 100 includes an image forming unit A and a paper feeding unit B.

The image forming section A includes a contact glass 101
A reading unit 103 for irradiating light on the original 102 placed on the reading unit and reading the reflected light (image information);
A writing unit 104 for outputting a laser beam based on the image information read by the scanner, mirrors 105 to 109 for guiding the laser beam in a predetermined direction, and an electrostatic latent image corresponding to the image information when irradiated with the laser beam And a photosensitive drum 111 rotated by a drive shaft 1 of a drive unit 11 described later.

A charger 11 for charging the surface of the photosensitive drum 111 is provided around the photosensitive drum 111.
And irradiating a laser beam corresponding to image information to the photosensitive drum 111 after the charging process,
A mirror 109 for forming an electrostatic latent image on the surface of the photosensitive drum 111; and a toner on the photosensitive drum 111 by supplying toner to the electrostatic latent image formed on the surface of the photosensitive drum 111 to visualize the electrostatic latent image. And a transfer unit 117 for transferring the toner image on the photosensitive drum 111 to a transfer material 114 such as copy paper.
A cleaning unit 120 that cleans the photoconductor drum 111 after the transfer process in preparation for the next copy process;
Is provided.

The image forming unit A includes a paper feed unit B
Roller 115 for feeding the transfer material 114 fed from the printer at a predetermined timing, a guide plate 116 for guiding the transfer material 114 in the direction of the photosensitive drum 111, and a toner image transferred to the transfer material 114 by the transfer device 117. A fixing device 118 including a fixing roller 119 and a pressure roller 121 for fixing the image, and a transfer material 114 on which a fixing process has been performed.
And a discharge tray 119 for receiving the sheet.

As shown in FIG. 1, the drive unit 11 includes a power transmission device 3 composed of a pulley (transmission member) 5 and a drive shaft 1, a timing belt 7, and a drive motor 9. 9 is transmitted to the pulley 5 via the timing belt 7, and the drive shaft 1 fastened to the pulley 5 transmits the driving force to the photosensitive drum 111 by rotation.

As shown in FIG. 2, the distal end 13 of the drive shaft 1
Has a taper in which both opposing side surfaces are symmetrically inclined and the leading end side becomes thinner. The circumferential diameter h of the distal end of the distal end portion 13 is equal to the diameter f of the connection hole 23 on the surface (hereinafter, referred to as a table) side of the pulley 5 on which the drive shaft 1 is not inserted.
(See FIG. 1). A hollow cylindrical screw hole 17 is formed at the center of the distal end portion 13.
The screw hole 17 is formed with a thread groove inside the hollow cylinder so as to receive the screw 15. Also, the tip 1
A stopper 19 for stopping one end of the photosensitive drum 111 is attached to the third side, so that the photosensitive drum 111 does not move earlier than the stopper 19.

The pulley 5 has a disk shape made of, for example, resin or the like, and has a notch 21 over its entire outer peripheral surface.
Are formed. At the center of the pulley 5, as shown in FIG. 3, a connection hole 23 for connecting the tip 13 of the drive shaft 1 is formed, and a taper matching the tip 13 is formed. The diameter f of the front side of the connection hole 23 is smaller than the diameter t of the head of the screw 15 so that the screw 15 can be stopped. The power transmission device 3 is formed by fitting the distal end portion 13 of the drive shaft 1 into the connection hole 23, tightening the screw 15 into the screw hole 17, and fastening the drive shaft 1 to the pulley 5. As shown in FIG. 4, a protrusion 29 for pressing the head of the screw 15 is attached to the front surface of the pulley 5.

As shown in FIG. 5, the projection 29 has an L-shaped cross section, and the bottom 31 of the projection 29
It extends in a direction (g direction in the figure) perpendicular to the surface of the pulley 5 from below the connection hole 23. The length of the bottom surface portion 31 in the g direction is shorter than the length of the screw 15, and the side surface portion 33 extends parallel to the surface of the pulley 5 from the tip surface. The side surface portion 33 extends from the front end surface of the bottom surface portion 31 to above the connection hole 23, and a notch portion 35 is formed at the front end of the side surface portion 33 as shown in FIG. 4.

The notch 35 is formed to allow a driver 37 to pass when the drive shaft 1 is fastened to the pulley 5 with the screw 15. The notch 35 has a substantially semicircular shape, and the diameter n of the semicircle is smaller than the diameter t of the head of the screw 15 so that the head of the screw 15 can hit the side surface 33 and press the side surface 33. Have been.

The timing belt 7 is made of a member such as rubber, for example, and includes a motor shaft 25 of the drive motor 9 and a pulley 5.
Through. The inner peripheral surface of the timing belt 7 is formed with irregularities that mesh with the notches 21 of the pulley 5 described above, thereby increasing the frictional force with the pulley 5.

Hereinafter, a method for assembling the drive shaft 1 to the pulley 5 and a method for removing it from the pulley 5 based on the above-described configuration will be described. When mounting, insert the distal end 13 of the drive shaft 1 into the connection hole 23 of the pulley 5, tighten the screw 15 into the screw hole 17 of the drive shaft 1 (see the arrow in FIG. 2), and attach the drive shaft 1 to the pulley 5. Fix it. (See FIG. 3).

When the screw 15 is loosened by a driver 37 as shown in FIG. 5, the screw 15 gradually moves in the direction g. Subsequently, when the screw 15 is loosened, the head of the screw 15 hits the side surface portion 33. further,
As the screw 15 is loosened, the head of the screw 15 pushes the side surface 33 in the direction g as shown in FIG. Therefore, the pulley 5 moves in the g direction and comes off the drive shaft 1.

In this embodiment, the pulley 5 rotates via the belt 7 by the output from the drive motor 9, and the pulley 5
Is rotated. In this state, the drive shaft 1 and the connection hole 23 are tapered,
The mutual engagement prevents the eccentricity and the loosening of the fastening portion from occurring, so that the fluctuation of the rotation speed of the drive shaft 1 and the backlash are prevented. Further, since the drive shaft 1 is fastened to the pulley 5 simply by tightening the screw 15 into the screw hole 17 formed in the tip portion 13 of the drive shaft 1, assembly and removal are easy, and maintenance is easy. It is. Further, the drive shaft 1 is fastened to the pulley 5 by the screw 15, and the fastening portion is strengthened, so that rattling is reliably prevented. Further, the pulley 5 is provided with a projection 29 for pressing the head of the screw 15, so that the pulley 5 can be easily detached from the drive shaft 1 only by loosening the screw 15. Therefore, removal of the pulley 5 is simplified. Furthermore, since the screw 15 is retained in the projection 29 and the connection hole 23 of the pulley 5 even after being removed from the screw hole 17, the screw 15 is prevented from dropping or being lost.

The present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist thereof. For example, in the present embodiment, the protrusion 29 extends from below the connection hole 23, but may have a configuration extending from above the connection hole 23. In the present embodiment, the present invention is applied to the photosensitive drum 111.
The same effect can be obtained by using a member driven by a combination of a member for transmitting power such as a pulley and a drive shaft for driving a roller or a drum, such as the fixing roller 119 and the pressure roller 121, and the fixing roller 119 and the pressure roller 121.

[0025]

According to the first aspect of the present invention, in the power transmission device, the drive shaft having the tapered end portion that matches the connection hole is connected to the transmission member having the connection hole tapered. With this configuration, fluctuations and rattling of the rotation speed of the drive shaft are prevented.

According to the second aspect of the present invention, rattling is more reliably prevented by tightening the screw and securely connecting the drive shaft to the transmission member. Also, assembling and dismounting are facilitated, and maintenance is also simplified.

According to the third aspect of the present invention, the transmission member is
When the screw is loosened, the structure provided with the protrusion that comes into contact with the screw facilitates removal of the transmission member and maintenance.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a driving device for driving a photosensitive drum.

FIG. 2 is a perspective view showing a power transmission device.

FIG. 3 is a sectional view taken along line AA in FIG. 2;

FIG. 4 is a perspective view of a pulley.

FIG. 5 is a sectional view taken along line BB in FIG. 4;

FIG. 6 is a cross-sectional view showing a state where a screw is loosened. .

FIG. 7 is a schematic diagram of a copying machine using the power transmission device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drive shaft 3 Power transmission device 5 Pulley (transmission member) 9 Drive motor 13 Tip 15 Screw 17 Screw hole 23 Connection hole 29 Projection 100 Copier (image forming apparatus)

Claims (3)

[Claims] 1. A power transmission device comprising: a transmission member that transmits an output from a drive motor provided in an image forming apparatus; and a drive shaft that transmits a driving force by rotation by fitting into a connection hole of the transmission member. In the above, the connection hole is formed with a taper that becomes narrower in the insertion direction of the drive shaft, and a taper that matches the connection hole is formed at the tip of the drive shaft. Power transmission device. 2. The power transmission according to claim 1, wherein a screw hole is formed in a tip portion of the drive shaft, and the transmission member and the drive shaft are fastened by a screw. apparatus. 3. The transmission member includes a protrusion protruding from a head side of the screw, and includes a protrusion that moves and abuts the head of the screw when the screw is loosened. The power transmission device according to claim 2.