JPS6098249A - Drive transmission mechanism of inage forming apparatus - Google Patents

Abstract

PURPOSE:To facilitate assembly and reduce the dimension of the captioned mechanism and improve reliability by allowing a chain and a sprocket to be engaged to transmit the power of a driving source, in a drive transmission mechanism which can be divided. CONSTITUTION:A driving sprocket 24 driven by a motor is installed onto an upper-side body 21, and a sprocket 24 and an idler sprocket 26 are arranged in separated form, and an endless chain 27 is laid between these sprockets. A trailing sprocket 29 is installed onto a lower-side body 22 ingtegrally with a shaft 28 for supporting a recording-paper transport roller so as to be engaged with the chain 27 in the state where the upper-side body 21 is closed. When the chain 27 and the trailing sprocket 29 are in engagement, the ilder sprocket 26 is urged in the direction for providing a tension onto the chain 27 by means of a spring 31.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a drive transmission mechanism in an image forming apparatus such as a copying machine whose main body can be divided into two parts.

Conventional Technology For example, in order to facilitate maintenance and jam removal of recording paper, a copying machine is divided into two parts, an upper body and a lower body, separated by the recording paper conveyance path. There is a so-called clamshell type that is divisible. In such a ramshell type copying machine, the main driven parts such as the document table for scanning the document, the reciprocating mechanism for the optical system, the photoreceptor, and the developing device are usually located on the upper main body. A motor as a drive source is built into the upper main body, and the driven parts of the lower main body are driven by transmitting the power of the motor provided in the upper main body by providing a drive transmission mechanism between the sub-main bodies. The drive transmission mechanism generally uses an idler gear.

FIGS. 1A and 1B show the structure of a drive transmission mechanism using a conventional idler gear. The upper body l has shaft 2
is rotatably supported, and a drive gear 8 is fixed to this shaft 2. The idler gear 4 is rotatably supported via a shaft 6 by an arm 5 rotatably provided around the shaft 2 so as to always mesh properly with the drive gear 8. On the other hand, a shaft 8 is rotatably supported on the lower body 7, and a driven gear 9 that meshes with the idler gear 4 when connected to the upper body 1 is fixed to the shaft 8. Note that the arm 5 is supported by a spring l in the direction in which the idler gear 4 meshes with the driven gear 9.
energized by O, the upper main body 1 and the lower main body 7 are divided, and the idler gear housing and the driven gear 9 come into contact with a stopper 11 when they are separated. In addition, when the driven gear 9 is driven through the idler gear assembly in which state the upper main body 1 and the lower main body 7 are connected, the idler gear 4 receives a force that bites into the driven gear 9, causing the pitch of these. In order to prevent meshing beyond the circle, the idler gear assembly and the driven gear 9 are provided with stopper discs 12 and 18, respectively, equal to their respective pitch circles to abut them.

However, in such a conventional drive transmission mechanism, since an idler gear is used, various setting conditions and a large number of parts are required as described above, which makes assembly difficult and expensive, and it is difficult to obtain sufficient reliability. In addition, there are drawbacks such as the fact that it requires space for installation and is large in size.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a drive transmission mechanism for an image forming apparatus that eliminates the above-mentioned drawbacks, can be easily assembled, is small and inexpensive, and is suitably configured to provide 10 times higher reliability. This is what I am trying to do.

Summary of the Invention The drive transmission mechanism of the present invention is an image forming apparatus such as a copying machine whose main body can be divided into two parts, in which an endless chain is connected to one of the divided parts and the chain is connected to the other part. A removable sprocket is provided for each part, and the chain and sprocket are engaged when the two parts are connected, so that the power of the drive source provided in either one of the two parts can be transmitted to the other part. It is characterized by the fact that

Example 2 to 4 show an embodiment of the present invention.

The copying machine main body 20 is separable into an upper main body 21 and a lower main body 2z with the recording paper conveyance path as a boundary, and the upper main body 2
1 is made to be able to open and close freely relative to the lower main body 22 with one end thereof serving as a rotation axis.

The upper main body 21 is equipped with main driven parts such as a document table for scanning a document, a reciprocating mechanism for an optical system, a photoreceptor, a developing device, and a recording paper conveyance roller.
A motor is attached to drive these. Further, a fixing device z8 is attached to the lower main body 22, and a conveyance roller for conveying the recording paper in the fixing device z8 and a conveyance roller for conveying the recording paper in a recording paper conveyance path other than the fixing device 2B. A driven part such as a roller is attached. In this example, the upper main body 21 is provided with a driving sprocket 24 driven by a motor serving as a driving source, and a sprocket 25 and an idler sprocket 2 are provided.
6 are provided at a distance from each other, and an endless chain z7 is passed around this sprocket to connect the drive sprocket 2.
By rotating the chain 27 by the lever 4, the driven portion within the upper main body 21 is driven. On the other hand, the chain 2? is attached to the lower body 2z when the upper body 21 is closed. For example, a driven sprocket 29 is provided integrally with the shaft 28 that supports the recording paper transport roller in the fixing device 28 so as to engage with the shaft 28 . The idler sprocket 26 is pivotally supported by the swinging arm 80 so as to be located near the driven sprocket 29 provided on the lower main body 2z when the upper main body 21 is closed, and the swinging arm 30 is supported by the spring 81. The chain 27 is energized in the direction of applying tension through the chain 27.

FIG. 2 shows a connected state in which the upper main body 21 is closed. In this state, the chain 27 and the driven sprocket 29 are engaged, and in this stopped state, the idler sprocket 29 located near the driven sprocket 29 is engaged. But spring 8
1 in a direction that applies tension to chain z7. Therefore, the power of the motor provided in the upper main body 21 can be effectively transmitted to the required driven parts of the lower main body z2 via the chain z7 and the driven sprocket z9. Further, when the upper main body 21 is opened and split into MK as shown in FIG. The sagging that occurs is
This is absorbed by the spring 81 displacing the idler sprocket 26 in a direction that applies tension to the chain 27 via the swing arm BO. That is, the spring 81 supports the chain 2 via the swing arm 80 and the idler sprocket 26 in both the connected state and the split state.
7 to provide the necessary tension.

In addition, in this embodiment, as shown in FIG.
8 is provided with a positioning guide part 84 into which the lower end of the part 8 fits,
When the upper main body 21 is closed, the lower end of the side plate 88 is fitted into the guide part 84. In this way, even if there is play in the rotating shaft of the upper body 21, the upper body 21 can always be connected to the lower body 22 in a predetermined state, so that the chain 27 and the driven sprocket 29 can always be connected. It can be engaged reliably.

Further, as described above, the driven sprocket 29 is connected to the fixing device 2.
When the shaft z8 is mounted on the shaft 28 that supports the recording paper transport roller in the shaft z8, the shaft z8 is normally provided with a relatively large play in its bearing in order to absorb thermal expansion due to heating. In order to prevent the driven sprocket 29 from shifting in the axial direction, the bearing on the driven sprocket 29 side of the shaft 28 has minimal play, and the bearing on the opposite side absorbs the thermal expansion of the shaft 28. do it like this.

Note that the present invention is not limited to the above-mentioned example, but can be modified or changed in many ways.

For example, if the winding angle of the chain z7 around the driven sprocket 29 is insufficient for the driving torque, the tension of the chain 27 causes the swinging arm 80 to move through the idler sprocket 26 against the force of the spring 81. In order to prevent it from being rotated, as shown in Figure 5,
A stopper 85 is provided so as to come into contact with the swing arm 80 at a predetermined position. In this way, the swing arm 8
Since the chain 27 receives a force in the direction of biting the driven sprocket 29, the chain 27 can be effectively prevented from undesirably rotating more than necessary.
Even if the winding angle around 29 is insufficient for the driving torque, the driving force can be reliably transmitted. Further, the division of the main body is not limited to the above-mentioned vertical direction, but may be in the horizontal direction or any other arbitrary direction, and the division plane does not necessarily have to be bordered by the recording paper conveyance path.

However, this drive source may be provided on the sprocket side that can be engaged with and detached from the chain. Further, the present invention is not limited to the above-mentioned copying machine, but can be effectively applied to facsimiles, electrostatic printing machines, and other image forming apparatuses.

Effects of the Invention As described above, according to the present invention, a chain and a sprocket that is removable from the chain are used to connect and disconnect the drive transmission path between the two divided parts. It is easy to assemble, is small and inexpensive, and has high reliability.

[Brief explanation of drawings]

FIGS. 1A and 1B are diagrams showing the configuration of a conventional drive transmission mechanism, FIGS. 2 to 4 are diagrams showing one embodiment of the present invention, and FIG. 5 is a main part of another embodiment of the present invention. FIG. 22...Lower body 28...Fuser 24...Drive sprocket 25...Sprocket 26...Idler sprocket 27...Chain 28...Shaft 29...Driver sprocket) 80...・Swing arm 8
1... Spring 82.88... Side plate 84... Guide portion 85... Stopper patent applicant Olympus Optical Industry Co., Ltd. Figure 1 A B Figure 2 Figure 3

Claims (1)

[Claims] 1. In an image forming apparatus such as a copying machine whose main body can be divided into two parts, one divided part is provided with an endless chain, the other part is provided with a sprocket that can be connected to and detached from the chain, and both parts are separated. The power of the image forming apparatus is characterized in that the power of a drive source provided in one of the two parts can be transmitted to the other part by engaging the chain and the sprocket when the two parts are connected. transmission mechanism.