JP2711334B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms a latent image on an image carrier such as a photosensitive drum through a predetermined image forming process, and transfers the latent image to a developing device with a developer. The present invention relates to an image forming apparatus such as a copying machine, a printer, etc., in which a visible image is formed, and the image formed on the image carrier is transferred to a transfer material and fixed. In the event of a drive abnormality occurring when the developing device or the like is driven, it is possible to detect the abnormality at an early stage, to effectively prevent damage and damage to the image forming apparatus, and to drive the image forming apparatus with a compact configuration. The present invention relates to an image forming apparatus having a simple driving device.

2. Description of the Related Art Conventionally, a latent image is formed on an image carrier such as a photosensitive drum through a predetermined image forming process, and the latent image is visualized by a developing device with a developer. In an image forming apparatus such as a copying machine or a printer, an image on an image carrier is transferred to a transfer material and fixed, and an image is formed through a process of cleaning a developer on the image carrier with a cleaner. By rotating an image carrier such as a photosensitive drum formed in a belt shape or a drum shape, a predetermined process such as a latent image forming process, a visible image forming process, and a transfer process necessary for image formation as described above is performed. I was

At this time, as a driving device for driving an image carrier such as a photosensitive drum (hereinafter, a drum-shaped one), a gear is provided on a flange portion formed integrally with the photosensitive drum, and the gear of the flange portion is provided with a gear. A method in which another gear is engaged from the outside and driven to rotate to drive the photosensitive drum, or a pin is provided on a photosensitive drum drive plate provided coaxially with the support shaft of the photosensitive drum, and this is driven to rotate. In some cases, a method is used in which the flange is integrally formed on the photosensitive drum with the pin and the flange is driven. In addition, the driving of the developing device used in the visible image forming process is performed by the gear provided on the flange of the photosensitive drum, or performed by disposing a completely different developing device driving device.

Some of these driving devices have a torque limiter that sets an upper limit of the driving torque in order to prevent the image forming apparatus from being damaged when an abnormal condition is applied to the load torque of the photosensitive drum, the developing device, the cleaner, or the like. A drive device having a suitable torque limiter is used for the waste toner container to prevent the waste toner transport unit from being damaged when the waste toner transport member is driven to rotate when the waste toner container is full. However, in the above-described conventional example, in a driving device of a type that simultaneously drives the developing device and the waste toner conveying member by driving a gear provided on a flange of the photosensitive drum, a torque for detecting an abnormal load torque is used. If the limiter is on the upstream side of the photosensitive drum drive system, unless the torque limiter capacity is set larger than all the load torques on the downstream side of the photosensitive drum, the load torque cannot be detected abnormally. The error with respect to the operating torque of the torque limiter increases.

That is, for example, the operating torque of the photosensitive drum is 4 kg
m ± 0.5kg ・ cm, cleaner operating torque 2kg ・ cm ± 0.2kg
・ If the operating torque of the developing unit is 8kg ・ cm ± 1kg ・ cm and the tolerance of the torque limiter itself is ± 10%, the setting of the operating torque of the torque limiter is 14kg ・ cm ± 1.7kg ・ cm. , 17.5kg · cm ± 1.8kgcm, and when the load torque is abnormal, the maximum is (17.5 + 1.8)-(14-1.7) = 7k
If g · cm torque is not generated, detection may not be possible.

In the torque limiter, when an abnormality of the load torque is detected with such a large torque, for example, when there is an abnormality inside the cleaner having the waste toner conveying member, when the abnormality is detected, a considerable amount has already been detected. It is highly probable that damage has occurred, and in the worst case, the unit may need to be replaced. Although it is possible to provide sufficient strength in preparation for such a case, such a measure is not preferable in terms of the space of the apparatus main body or the cost of parts.

Further, in order to prevent the occurrence of an abnormality inside the cleaner as described above, in the case where the waste toner conveying member of the waste toner container has a torque limiter independently, the operation of the torque limiter is reliable. However, if the user keeps copying without noticing the operation sound of the abnormal display, the toner may be dropped due to toner dripping from the cleaner unit having the waste toner conveying member. Some of them caused problems such as scattering in the device.

Further, in the case where the drive of the developing device is performed by a drive system of another system, the above-described drawback does not occur by disposing the torque limiter on the upstream side of the drive system of the photosensitive drum. However, such a measure that the number of parts is increased and that it is difficult to reduce the size of the apparatus main body is caused by the measure of dividing the drive system.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a developer conveying unit such as a waste toner conveying member for conveying a developer removed from a photosensitive drum when a photosensitive drum is driven to form an image. The developing means for developing the latent image on the photosensitive drum is also driven by a driving means having a compact configuration, and the overload of the developer conveying means is detected with high accuracy in a small space. It is an object of the present invention to provide an image forming apparatus provided with a driving device capable of performing the operation.

Means for Solving the Problems The above objects are achieved by an image forming apparatus according to the present invention. That is, in summary, in an image forming apparatus for forming an image on a recording medium according to the present invention, a photosensitive drum, a developing unit for developing a latent image formed on the photosensitive drum, and a developer removed from the photosensitive drum Developer transporting means for transporting the photosensitive drum, a drive unit disposed on a rotatable shaft supporting one end of the rotation center of the photosensitive drum, and a developing unit provided on an outer periphery of the drive unit. A driving gear for driving; a torque limiter provided inside the driving unit; and a first driving force transmitting means for transmitting a driving force of the driving gear to the photosensitive drum via the torque limiter. A second driving force transmission for transmitting the driving force transmitted to the photosensitive drum by the first driving force transmitting unit from the photosensitive drum to the developer conveying unit; And a third driving force transmitting unit for transmitting the driving force of the driving gear to the developing unit without passing through the torque limiter, wherein an overload occurs in the developer conveying unit. Preferably, the torque limiter cuts off the transmission of the driving force to the photosensitive drum to stop the rotation of the photosensitive drum.

Examples Hereinafter, the present invention will be described based on examples with reference to the accompanying drawings.

Referring to FIG. 1, there is schematically shown an embodiment of an image forming apparatus according to the present invention.

The image forming apparatus shown in FIG. 1 includes a photosensitive drum 1 as an image carrier, and the photosensitive drum 1 is formed in a drum shape (cylindrical shape) and rotates in a direction indicated by an arrow. Around the photosensitive drum 1, a charging device 2 for uniformly charging the surface of the photosensitive drum 1 along its rotation direction, and a laser optical system, for example, for forming a latent image on the photosensitive drum 1 are used. An exposure device 4 for performing exposure according to image information
A developing device 6 for attaching a toner as a developer to the latent image formed on the photosensitive drum 1 to form a visible image, a transfer charging device 8 for transferring the visible image on the photosensitive drum to a transfer material P as a recording medium, Fixing device for fixing a transfer image on transfer material P
10, a cleaning device 12 for cleaning residual toner on the photosensitive drum 1 and the like are provided.
Is provided with a developer conveying means for conveying the cleaned residual toner to the side of the cleaning device 12, for example, a waste toner conveying member 13 composed of a screw member or the like.

The image forming process for forming an image with such a configuration is a technique well-known to those skilled in the art, and therefore will not be described in further detail.

Here, referring to FIG. 2 which shows a part of the periphery of the photosensitive drum 1 shown in FIG. 1 in detail, a flange 14 is fixed to the photosensitive drum 1,
A gear 14a for transmitting a driving force to the above-described waste toner conveying member 13 is formed on the outer peripheral portion of the. Flange 1
4 is loosely supported at its center by a shaft 16 rotatably disposed on the apparatus main body 15. Therefore, the photosensitive drum 1 is rotatably supported on the apparatus main body 15 via the shaft 16.

Further, a substantially cylindrical gear 17 as a drive unit is disposed coaxially with a rotatable shaft 16 supporting one end of the rotation center of the photosensitive drum 1, and a torque limiter 17A is provided in the gear 17. It is included. The photosensitive drum 1 is driven via the torque limiter 17A. That is, drive gear 1
7, a coil-shaped spring 18, a ring-shaped limiter plate 19, a substantially cylindrical drive plate 20 having a step portion, as shown in the drawing,
The torque limiter 17A as a whole is built in such that it is arranged at a predetermined position (see FIG. 3). The drive plate 20 of the torque limiter 17A has a flange 14
A pin 20a is provided so as to project to the side, and this pin 20a is adapted to engage with a rib 14b of the flange 14 (see FIG. 4). An idler gear 21 meshes with a gear 14a formed on the outer periphery of the flange 14, and a meshing gear portion 21a of the idler gear 21 has waste toner for driving the waste toner carrying member 13 of the waste toner carrying portion. The transport member drive gear 23 is engaged.

A gear portion 17a for driving the developing device is formed on the outer peripheral portion of the gear 17. That is, a sleeve gear 25 fixed to the developing sleeve 24 meshes with the gear portion 17a.

Here, the configuration of the above-described torque limiter 17A will be further described.

As shown in FIG. 3, three grooves 17b are formed at predetermined positions on the inner periphery of the gear 17 which is formed in a substantially cylindrical shape as a drive unit, and these grooves 17b are formed on the outer periphery of the limiter plate 19. The limiter plate 19 is engaged with a claw 19b provided at a predetermined position.
The gear 17 is slidable in the axial direction of the gear 17 while being built in. At a predetermined position on the outer peripheral side surface of the limiter plate 19,
Further, three trapezoidal convex portions 19a are formed, and trapezoidal concave portions formed at predetermined positions on the outer peripheral side surface of the drive plate 20.
20b is engaged. Then, the drive plate 20 is fitted to the inner diameter of the gear 17.

Thus, when the drive plate 20, the limiter plate 10, and the spring 18 are set inside the gear 17 at a predetermined position (shown in FIG. 2), when the gear 17 is rotationally driven, the drive plate
Limiter plate 19 against the load torque applied to pin 20a
Tries to rotate, but the rotating force at this time is
Since the projection is transmitted to the drive plate side by the engagement of the projection 19a of the drive plate 19 and the recess 20b of the drive plate 20, a force is exerted on the limiter plate 19 in the direction of the trapezoidal slope. At this time, the limiter plate 19 has a trapezoidal slope while the above-described force for escaping the limiter plate 19 is smaller than the combined force of the frictional force of the spring 18 and the limiter plate 19 and the frictional force of the slope on the limiter plate 19. The rotation is transmitted to the drive plate 20 without escaping in the direction. However, when the load torque applied to the pin 20a of the drive plate 20 increases, the force of the limiter plate 19 to escape in the trapezoidal slope direction also increases, and this escape force is reduced by the spring 18 and the limiter plate 19.
When it becomes larger than the resultant force of the frictional force and the frictional force of the slope on the limiter plate 19, the limiter plate 19 escapes from the trapezoidal slope, that is, slides along the groove 17b,
The rotation is not transmitted to the drive plate 20. This time is when the torque limiter 17A operates. It goes without saying that the value at the time of operation of the torque limiter 17A can be set to an appropriate value by suitably setting the angle of the slope, the coefficient of friction, and the force of the spring 18.

In such a configuration, the shaft 16 is driven by a driving source (not shown).
Gear 17 as a driving means,
It rotates with the rotation of 16, and drives the developing sleeve 24 and the stirring mechanism 6a (see FIG. 1) in the developing device 6 via the sleeve gear 25.

Further, with the rotation of the gear 17, as shown in FIGS. 2 and 3, the spring 18, the limiter plate 19, the drive plate 20, the pin 20
The driving force is transmitted in the order of a, and the pin 20a rotates the flange 14 and the photosensitive drum 1 by hooking the rib 14b of the flange 14 shown in FIG. Further, since the idler gear 21 meshes with the gear 14a formed on the outer peripheral portion of the flange 14, the waste toner transport member driving gear 23 and the waste toner transport member are connected via the idler gear 21 and the meshing gear portion 21a.
13 will be driven. Therefore, in this case, the pin 20a
, A load torque by the photosensitive drum 1 and the waste toner conveying member 13 is applied.

Thus, in the above embodiment according to the present invention, the torque limiter 17A and the pins 20a and the ribs 14b as the first driving force transmitting means are provided by the gear 17 as the driving means having the torque limiter having the above-described configuration therein. And as the second driving force transmission means, for example, the gears 14a, 21, 21a,
23, the photosensitive drum 1 and the waste toner conveying unit
Since the drive unit 13 is driven, it is possible to set the operating point of the torque limiter with higher sensitivity as compared with the related art, even in the case of the abnormality of the drive unit having a small normal load.

Further, as described above, in the present embodiment, the third driving force transmitting means such as the gear portion 17a formed on the outer peripheral surface of the gear 17 as the driving unit having the torque limiter 17A therein and the sleeve gear 25 is used. Directly, torque limiter 17A
It is possible to drive the developing device 6 without the intermediary of the device, and it is possible to minimize the space of the device main body. That is, in the present invention, a drive unit, that is, a gear 17 is provided on a rotatable shaft 16 that supports one end of the rotation center of the photosensitive drum, and a developing device drive gear 17a is provided on an outer periphery of the gear 17, and a gear is provided. By incorporating a torque limiter 17A inside the photosensitive drum 17 and driving the photosensitive drum 1 via the torque limiter 17A, a compact drive mechanism can be achieved.

Here, as an example of an actual load torque, when the above-described embodiment of the present invention is used, the load torque of the photosensitive drum 1 and the waste toner transport unit 13 is 4 kg · cm ± 0.5 kg · cm, and the developing device When the load torque of is 4kg ・ cm ± 1.5kg ・ cm, when the waste toner container is full, the torque limiter of 5kg ・ cm ± 0.5kg ・ cm can detect the load torque and the maximum error is , 5.5−3.5 = 2 kg · cm. On the other hand, in the conventional example described above, the torque limiter used must be set to 11 kg · cm ± 1.1 kg · cm.
The maximum error is 12.1kgcm-6kgcm = 6.1kgcm,
Unless there is an increase in load torque of about 6 kg · cm, detection cannot be performed.

Further, according to the above configuration, since the photosensitive drum 1 stops rotating together with the operation of the torque limiter, when the torque limiter is operated, an image is intermittently blank, and an abnormal display can be reliably displayed to the user.

It is also clear that the present invention depends only on the position of the torque limiter, irrespective of the type of the torque limiter.

Further, the effect of the present invention is not lost by the shape of the photosensitive drum, and a sufficient effect can be obtained even for a belt-shaped one.

Effects of the Invention As described above, according to the present invention, a drive unit is provided on a rotatable shaft that supports one end of a rotation center of a photosensitive drum, and a developing device drive gear is provided on an outer periphery of the drive unit. Since the drive unit includes a torque limiter and the photosensitive drum is driven via the torque limiter, the drive mechanism can be made compact and a small space can be realized, and the driving force of the photosensitive drum can be further reduced. Since the power is transmitted to the developer conveying means, and the driving gear is also directly driven by the driving gear, the torque limiter can be operated without burdening the load for driving the developing means. As a result, it is possible to set a highly sensitive torque limiter value for the developer conveying means, and as a result, it is possible to more accurately detect that the overload has occurred in the developer conveying means. It is possible to quickly detect abnormalities in the load torque on the developer conveying means, and to notify the user of the abnormalities without fail. In addition, the photosensitive drum and the developer conveying means can be driven by one driving means. Further, since the developing means can be driven, the space of the apparatus main body can be minimized.

[Brief description of the drawings]

FIG. 1 is a schematic sectional explanatory view of an embodiment of the image forming apparatus according to the present invention. FIG. 2 is a partial view showing in detail a peripheral portion of the photosensitive drum 1 shown in FIG. FIG. 3 is a perspective view of a torque limiter built in and configured in a gear as a drive unit used in FIG. FIG. 4 is a perspective view showing a flange portion of the photosensitive drum used in FIG. 1: Image carrier 6: Developing device 13: Waste toner transport member 17: Drive unit 17A: Torque limiter P: Transfer material

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tatsuya Shiratori 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Naomasa Kimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Eiichi Ando 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masanari Shirai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yoshikuni Toyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masashi Ohashi 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo Canon Inc. (56) References JP-A-60-188627 (JP, A) JP-A-60-247279 (JP, A) JP-A-62-279355 (JP, A) Japanese Utility Model 60-150567 (JP, U)

Claims (1)

(57) [Claims] 1. An image forming apparatus for forming an image on a recording medium, comprising: a photosensitive drum; a developing unit for developing a latent image formed on the photosensitive drum; and a developer removed from the photosensitive drum. And a driving unit disposed on a rotatable shaft that supports one end of the rotation center of the photosensitive drum, and driving the developing unit provided on an outer periphery of the driving unit. A driving gear for transmitting a driving force of the driving gear to the photosensitive drum via the torque limiter; and a torque limiter provided inside the driving unit. Second driving force transmitting means for transmitting the driving force transmitted to the photosensitive drum by the first driving force transmitting means from the photosensitive drum to the developer conveying means; A third driving force transmitting means for transmitting the driving force to the developing means without passing through the torque limiter, wherein the torque limiter is provided when the developer conveying means is overloaded. Wherein the transmission of the driving force to the photosensitive drum is cut to stop the rotation of the photosensitive drum.