JP2006251269A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus with which the attaching and detaching property of an image formation unit can be improved without requiring a surplus cost and space. <P>SOLUTION: A two-stage speed change gear 42 on an apparatus main part side comprises a large-diameter gear 42a and a small-diameter gear 42b which is formed coaxially with the large-diameter gear 42a and similarly rotates. In mounting a fixing unit to the apparatus main part, a gear 23 of the fixing unit and the small-diameter gear 42b are engaged with each other. As a drive transmission means between the large-diameter gear 42a and the small-diameter gear 42b, a projection 43 of a sectorial shape projecting from the small-diameter gear 42b toward the large-diameter gear 42a is provided and the projection 43 is accepted by a hole or recess 44 of a sectorial shape projecting from the small-diameter gear 42b toward the large-diameter gear 42a. As a result, the fixing unit can be mounted on the apparatus main part with smaller force. In addition, portions of the respective gears can be interconnected without requiring separate components and the cost can be reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more particularly to an image forming apparatus in which an image forming unit can be easily attached and detached.

  A charging device, an exposure device, a developing device, a transfer device, a fixing device, and the like are arranged around a photoconductor as an image carrier of the image forming apparatus. These devices are usually used alone or with other devices. The image forming apparatus main body is detachable as a unit.

As a prior art relating to such an image forming apparatus and the like, for example, Patent Document 1 discloses a swing member that is mounted on an image forming apparatus and whose drive switching means is pivotally supported in the main body of the image forming apparatus, and a transmission gear at a gear end. Has a spring that urges it in the direction to release it from the gear on the fixing means side, and when the open / close door for jamming is closed, the interlocking operation member pushes the elastic operation end, and the elastic force of the spring operates. By eliminating the state applied to the end, the transmission gear is maintained in a normal position for driving with the gear, and when the door is opened, the interlocking operation member eliminates the pushing of the elastic operation end, so that the transmission gear is removed from the gear. A drive release device of an image forming apparatus that makes a transition to a release position posture to be detached is disclosed.
Further, in Patent Document 2, in a device in which a drive-side gear to which rotation is transmitted from a drive source and a driven-side gear coupled to a load are engaged so as to be connectable, an intermediate portion that engages with a gear from the drive source. A drive side gear meshing with the gear on the driven side, and the intermediate gear and the drive side gear are connected with a coaxial clutch so as to have a play in the rotation direction; the drive side gear and the driven side A drive transmission device is disclosed in which the play always exists in both directions of rotation when the gears are separated.

Further, in Patent Document 3, a rotating body is detachably provided, and when the rotating body is attached, the connecting gear of the rotating body is meshed with the connected gear of the gear transmission means, and the rotation of the drive motor is transmitted to the gear transmission. In the apparatus for driving the rotating body by transmitting through the means, when the connecting gear interferes with the connected gear when the rotating body is attached, a rotational force in the rotation transmitting direction acts on the connected gear. In addition, there is disclosed a rotating body drive device in which a play in the rotation transmission direction is provided on a downstream member with respect to an upstream member of the gear transmission means.

JP 2004-117394 A Japanese Patent Application Laid-Open No. 07-257776 JP-A-11-315891

In general, in an image forming apparatus having a detachable unit, a drive transmission device, etc., when the unit is mounted, when the gear for connecting the drive between the main body and the unit is engaged, depending on the position of the teeth between the main body and the main body, As the fitting with the unit proceeds, the gear moves while rotating, and finally the unit is mounted at an ideal meshing position. However, in this case, if the rotational load of the unit or the drive motor is large, the force required to rotate the gear also increases, and a large force is required for mounting the unit, resulting in poor fit. This is the same not only when the unit is mounted but also when it is detached.
Therefore, in the prior art, for example, by allowing the gear portion that engages the main body on the driving side and the unit on the driven side to swing, or by using the clutch to make the gear rotatable except during operation, A load is not applied when the unit on the driven side is attached or detached.

However, such conventional techniques have the following problems. In other words, the provision of the oscillating gear mechanism or the clutch means has a problem that not only the number of parts is increased and the cost is increased, but also a necessary space is increased.
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 improving the detachability of the image forming unit without requiring extra cost and space. There is.

In order to solve the above problems, an image forming apparatus according to the present invention is formed with a drive device, a first gear driven by the drive device, and the first gear, and rotates together with the first gear. And an image forming unit that includes a third gear that meshes with the second gear of the apparatus main body and is detachably provided to the apparatus main body. In the forming apparatus, the second gear of the apparatus main body is rotatable with respect to the first gear within a range of less than 360 °.

In the present invention, the second gear is provided independently of the first gear and has an engaging projection extending toward the first gear, and the first gear is And an engagement portion that engages with the engagement protrusion of the second gear.
In the present invention, a plurality of the engaging protrusions and a plurality of engaging portions engaging with the protrusions are provided, and the protrusions are equally arranged on the same circumference along the circumferential direction of the first gear or the second gear. Can be. The number of the protrusions and the number of engaging portions that engage with the protrusions are not particularly limited, but it is preferable that the number is 3 or more.
Furthermore, in the present invention, it is preferable that the radius of the circle forming the circumference is not less than the radius of the second gear and not more than the radius of the first gear.

Furthermore, in the present invention, when the elastic body is interposed in the connecting portion of the first gear and the second gear, and the image forming unit is detached from the apparatus main body, the second gear and the first gear. It is preferable to secure a predetermined space for the second gear to rotate at the connecting portion.
Furthermore, in the present invention, the apparatus main body may include a positioning pin, and the image forming unit may include a notch that engages with the positioning pin. In this case, a positioning pin may be provided in the image forming unit, and a notch that engages with the positioning pin may be provided in the apparatus main body.
Furthermore, in the present invention, the image forming unit can be a process cartridge.

According to the image forming apparatus of the present invention, a special part for making the image forming unit detachable from the apparatus main body is unnecessary, and the number of necessary parts can be reduced to reduce the manufacturing cost. Further, the load applied to the connecting gear and the image forming unit itself when the image forming unit is attached to and detached from the apparatus main body can be remarkably reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment. 2 is a perspective view of a fixing unit which is one of image forming units, and FIG. 3 is a cross-sectional view of FIG.
In FIG. 1, the image forming apparatus 100 includes four process cartridges 6Y, M, C, and K for generating toner images of yellow, magenta, cyan, and black (hereinafter referred to as Y, M, C, and K). It has. These use Y, M, C, and K toners of different colors as the image forming material, but the other configurations are the same and are replaced when the lifetime is reached.

2 and 3, the fixing unit 20 applied to the present embodiment includes a fixing roller 21, a pressure roller 22 that rotates in contact with the fixing roller 21, a fixing roller 21, the pressure roller 22, and the apparatus main body. And a unit gear A (hereinafter referred to as a third gear) 23 that couples the drive source. The fixing unit 20 rotates the fixing roller 21 and the pressure roller 22 for heating and pressure-bonding the toner by the third gear 23 being connected to the driving gear on the apparatus main body side when the main body is mounted, thereby recording paper. When the fixing unit is passed, the toner image formed on the recording paper is fused to the recording paper. Note that a fixing belt may be used instead of the fixing roller 21.

4 is a perspective view showing a drive gear train on the apparatus main body side, and FIG. 5 is a view showing the two-stage reduction gear of FIG. In FIG. 4, the drive gear train 40 on the apparatus main body side is mainly composed of a motor 41 and a two-stage transmission gear 42 driven by the motor 41. In FIG. 5, the two-stage transmission gear 42 includes a large-diameter first gear 42a and a small-diameter second gear 42b that is formed coaxially with the first gear 42a and rotates simultaneously.
The first gear 42a is coupled to the motor 41, and the second gear 42b is coupled and driven by meshing with the third gear 23 (see FIG. 2 or 3) on the fixing unit side. The fixing unit 20 having the third gear 23 is detachable from the main body for unit maintenance, recording paper jam processing, and the like. When the unit is mounted, the two-stage transmission gear of the drive gear train 40 on the apparatus main body side. The second gear 42b in 42 and the third gear 23 on the image forming unit side mesh with each other.

Here, a method of attaching / detaching the fixing unit to / from the image forming apparatus will be described. When the fixing unit 20 is mounted on the apparatus main body, the fixing unit 20 is guided along a slide rail provided on, for example, a mold side plate of the apparatus main body. From a predetermined position where the fixing unit 20 can be easily placed to a position where the third gear 23 of the fixing unit 20 and the second gear 42b on the apparatus main body side mesh well, for example, by moving the fixing unit 20 into the main body device in the horizontal direction. Put it in. At this time, the position of the gear teeth of the third gear 23 of the fixing unit 20 and the second gear 42b on the apparatus main body side is not in the meshed state of the mountain and valley, but in a state where the mountain and the mountain face each other. Then, the gear teeth interfere with each other, and the fixing unit 20 is mounted in the apparatus main body while rotating the gears until a good meshing state (a position where the involute curves of the gears are in contact with each other).

In such an image forming apparatus, the rotational load of the motor whose power is decelerated and transmitted by the gear and the fixing roller to which a predetermined pressure is applied are large. For example, as shown in FIG. If the structure does not have a portion, a large force is required when the unit is attached or detached. In particular, as shown in FIG. 7, the meshing position between the third gear 23 on the fixing unit 20 side and the second gear 42 b on the apparatus main body side is the third gear with respect to the moving direction of the fixing unit 20. When the line connecting the shaft centers of the second gear and the second gear intersects at a substantially right angle, the amount of gear rotation until the gears mesh with each other increases, so that the detachability of the unit is further deteriorated.

Therefore, in the present invention, the two-stage transmission gear 42 on the apparatus main body side is constituted by the first gear 42a that is a large-diameter gear and the second gear 42b that is a small-diameter gear. The small diameter gear 42b is rotatable within a range of less than 360 °. In this case, the large-diameter gear 42a and the small-diameter gear 42b can be made separate and independent.
FIG. 8 is a perspective view showing the two-stage transmission gear in the present embodiment divided into a large-diameter gear and a small-diameter gear. In FIG. 8, a large-diameter gear 42a and a small-diameter gear 42b are coaxial and configured to be fitted and detached. That is, in this embodiment, not only the large diameter gear 42a and the small diameter gear 42b are rotatably connected but also the small diameter gear 42b is connected to the large diameter gear 42a in order to transmit the driving force from the motor to the fixing unit 20. Similarly, they are connected so as to rotate. As a drive transmission means between the large diameter gear 42a and the small diameter gear 42b, for example, a fan-shaped protrusion 43 extending from the small diameter gear 42b toward the large diameter gear 42a is provided, and this protrusion 43 is provided on the large diameter gear 42a. By being received by the fan-shaped hole or recess 44 provided as the engaging portion, it is possible to connect using a part of each gear without requiring a separate part. The cost required for the connection between the two gears 42a and 42b in the step transmission gear 42 can be reduced.

Further, since the small-diameter gear 42b can be moved without load when the fixing unit 20 is attached to the apparatus main body, the fixing unit 20 can be attached to the apparatus main body with a small force. In this case, the fan-shaped protrusions 43 and / or the fan-shaped holes or dents 44 may be formed as part of the rib shape of each gear. Even if the two-stage transmission gear divided into two is provided on the fixing unit 20 side instead of the apparatus main body side, the same effect can be obtained.

The operation of the image forming apparatus according to the present embodiment having such a configuration will be described below. When the fixing unit 20 shown in FIGS. 2 and 3 is attached to the image forming apparatus main body, the fixing unit 20 is inserted along a slide rail 53 (see FIG. 13 described later) provided on, for example, a mold side plate of the apparatus main body. To do. That is, the fixing unit 20 is moved from the predetermined position α where the fixing unit 20 can be easily placed to the inside of the main body device, for example, in the horizontal direction, and the third gear 23 of the fixing unit 20 and the second gear 42b on the main body side of the fixing unit 20 mesh. Insert to position β.
At this time, the positions of the teeth of the third gear 23 of the fixing unit 20 and the second gear 42b on the apparatus main body side are not in the relationship between the peaks and valleys in which the gears are engaged, but in a state where the peaks and peaks face each other. In this embodiment, the two-speed gear 42 is composed of a large diameter gear 42a and a small diameter gear 42b, and the small diameter gear 42b is 360 with respect to the large diameter gear 42a. By being provided so as to be rotatable within a range of less than 0 °, the fixing unit 20 can be pushed into the apparatus main body while rotating the small-diameter gear 42b until a good meshing state is achieved, and the third gear 23 is moved to the two-speed gear. 42, the fixing unit 20 is mounted on the apparatus main body.

According to the present embodiment, the two-stage transmission gear 42 is constituted by a large diameter gear 42a and a small diameter gear 42b, and the small diameter gear 42b is rotatably provided in a range of less than 360 ° with respect to the large diameter gear 42a. The small-diameter gear 42b is provided with a projection 43 extending toward the large-diameter gear 42a, the first gear 42a is provided with a fan-shaped hole or recess 44 with which the projection 43 engages, and the small-diameter gear projection 43 has a large diameter. Since both are connected by engaging with the gear hole or recess 44, the load when the fixing unit 20 is mounted on the apparatus main body can be remarkably reduced. In addition, the number of parts required to make the fixing unit 20 detachable from the apparatus main body is reduced, and the manufacturing cost can be reduced.

In the present embodiment, for example, there are four protrusions 43 and fan-shaped holes or depressions 44 for connecting the large-diameter gear 42a and the small-diameter gear 42b, and they are evenly arranged on the same circumference along the circumferential direction of the gear. It is preferable to arrange. FIG. 9 is a perspective view showing a small-diameter gear 42b in which a plurality of protrusions 43 extending toward the large-diameter gear 42a are evenly arranged along the circumferential direction of the gear 42a. Thus, by arranging the projections 43 evenly, the amount of movement that can be freely rotated can be controlled, and the load applied to the connecting portion of both gears can be dispersed, so that the durability is improved.

In this embodiment, the projection 43 that connects the large-diameter gear 42a and the small-diameter gear 42b and the fan-shaped hole or recess 44 into which the projection 43 is fitted are provided on the same circumference of each gear. The radius of the circle to be formed is preferably not less than the radius of the small-diameter gear 42b and not more than the radius of the large-diameter gear 42a. As a result, the force acting on the engaging portion of both gears due to the moment of force can be reduced, so that not only the durability is improved, but the member shape of the engaging portion can be reduced, and the necessary cost is reduced. It can be further reduced.

  As described above, the small-diameter gear 42b is rotatable within a range of less than 360 ° with respect to the large-diameter gear 42a. However, depending on the positional relationship between the large-diameter gear 42a and the small-diameter gear 42b, the fixing unit 20 is connected to the apparatus. When mounting on the main body, as shown in FIG. 10, there may be a case where there is no space in the direction in which the second gear 42b, which is the apparatus main body side gear, should move freely by the third gear 23 on the fixing unit side. In such a case, even if the small-diameter gear 42b is configured to be rotatable, it does not move freely, so that a large force is eventually required when the fixing unit 20 is mounted. Therefore, in the present embodiment, as shown in FIG. 11, for example, a spring member 45 is attached as an elastic body to the connecting portion between the large diameter gear 42 a and the small diameter gear 42 b of the two-stage reduction gear 42, and the fixing unit 20 is attached. When the fixing unit 20 is mounted, a force is applied in a direction opposite to the direction of the force received by the small diameter gear 42b when the fixing unit 20 is mounted, thereby ensuring a space for the small diameter gear 42b to rotate freely when the fixing unit 20 is mounted. It is preferable to do so. As a result, the fixing unit 20 can be attached to the apparatus main body with always a small force.

  In the present embodiment, the image forming unit is preferably a process cartridge. FIG. 12 is a diagram showing a process cartridge applied in the present embodiment. In FIG. 12, a photosensitive unit 200A and a developing unit 200B as process cartridges are described. The photoconductor unit 200A mainly includes a photoconductor drum 3, and a charging roller 7, a cleaning roller 7B, a cleaning blade 11B, and a toner transport auger 11C provided in the vicinity of the periphery of the photoconductor drum 3. By using the image forming unit as the process cartridge in this way, the process cartridge can be attached to or detached from the apparatus main body with a small force, so that high usability can be provided.

In the present embodiment, it is preferable that a positioning pin for positioning the fixing unit to be mounted on the apparatus main body is provided on the apparatus main body side, and a notch for engaging with the positioning pin is provided on the fixing unit side. FIG. 13 is a view showing the apparatus main body 54 having the fixing unit positioning pins 51 and the fixing unit 20 that is a fixing unit attached to the apparatus main body 54 and has a notch 52 that fits the positioning pins 51. With such a configuration, the mounting state of the fixing unit 20 to the apparatus main body 54 is stabilized. When the fixing unit 20 is mounted on the apparatus main body 54 along the slide rail 53, the positioning pin 51 is not only cut off in the third gear 23 and the small-diameter gear 42b, which is the second gear. The force is applied in the direction in which the force acts when mating with the portion 52, for example, the vertical direction, and the rotational load due to the meshing of the gears increases. Is constituted by a large-diameter gear 42a and a small-diameter gear 42b, and the small-diameter gear 42b is provided so as to be rotatable within a range of less than 360 ° with respect to the large-diameter gear 42a. Since the unit mounting load due to the fitting of the unit notches 52 is reduced, the fixing unit 20 can be attached to the apparatus main body with a small force.

1 is a schematic configuration diagram of an image forming apparatus according to the present invention. FIG. 4 is a perspective view of a fixing unit that is one of image forming units. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. It is a perspective view which shows the drive gear train by the side of the main body apparatus in this embodiment. It is a figure which shows the 2 step | paragraph reduction gear part of FIG. It is explanatory drawing which shows the state without the part which becomes free to rotate between gear trains. FIG. 6 is a diagram illustrating a relationship between a meshing position of a third gear and a second gear and a moving direction of the fixing unit 20. It is a perspective view which shows the two step transmission gear in this embodiment. It is a perspective view which shows an example of the small diameter gear in this embodiment. It is a figure which shows the engagement state of a 3rd gear and a 2nd gear. It is a figure which shows the large diameter gear and the small diameter gear by which the elastic body is arrange | positioned at the connection part. It is a figure which shows the process cartridge applied in this embodiment. It is a figure which shows the fixing unit which has an apparatus main body which has a positioning pin, and a notch part.

Explanation of symbols

3: Photosensitive drum (image carrier)
7: Charging roller 7A: Core 7B: Cleaning roller 11B: Cleaning blade 11C: Toner transport auger 20: Fixing unit 21: Fixing roller 22: Pressure roller 23: Third gear (unit gear A)
40: Drive gear train 41 on the main unit side: Motor 42: Two-speed gear 42a: Large-diameter gear 42b: Small-diameter gear 43: Projection 44: Fan-shaped hole or depression 45: Spring member 51: Positioning pin 52: Notch Unit 53: slide rail 54: apparatus main body 100: image forming apparatus 200A: photoconductor unit 200B: developing unit

Claims (7)

  A device main body comprising a drive device, a first gear driven by the drive device, and a second gear formed coaxially with the first gear and rotating together with the first gear, and the device An image forming apparatus comprising: a third gear that meshes with the second gear of the main body; and an image forming unit that is detachably provided to the apparatus main body. An image forming apparatus capable of rotating within a range of less than 360 ° with respect to the first gear.   2. The image forming apparatus according to claim 1, wherein the second gear includes an engaging protrusion that is provided independently of the first gear and extends toward the first gear. The image forming apparatus according to claim 1, wherein the first gear has an engaging portion that engages with an engaging protrusion of the second gear.   3. The image forming apparatus according to claim 2, wherein there are a plurality of engaging protrusions and a plurality of engaging portions engaging with the protrusions, and the same circumference along a circumferential direction of the first gear or the second gear. An image forming apparatus, wherein the image forming apparatus is uniformly arranged on the top.   4. The image forming apparatus according to claim 3, wherein a radius of a circle forming the circumference is not less than a radius of the second gear and not more than a radius of the first gear.   5. The image forming apparatus according to claim 2, wherein an elastic body is interposed in a connecting portion between the first gear and the second gear, and the image forming unit is detached from the apparatus main body. An image forming apparatus characterized in that a predetermined space for rotating the second gear is secured at a joint portion between the second gear and the first gear. 6. The image forming apparatus according to claim 2, wherein the apparatus main body includes a positioning pin, and the image forming unit includes a notch that engages with the positioning pin. Forming equipment.   The image forming apparatus according to claim 1, wherein the image forming unit is a process cartridge.

Images