Patent Description:
In conventional image forming apparatuses, there is known a configuration in which a drive gear train is disposed outside a main body side plate, and a drive side plate is attached to the main body side plate to cover the drive gear train from the outside so that the drive gear train is interposed between the main body side plate and the drive side plate.

<CIT> discusses a hollow member for connecting a hole on the main body side plate with a hole on the drive side plate, and also discusses a configuration for guiding cables via this hollow member. This configuration enables the cable to be wired through the main body side plate and the drive side plate without interference with the drive gear train. More specifically, the configuration makes it possible to connect a circuit board provided inside the main body side plate with a circuit board provided outside the drive side plate with the shortest distance.

However, in the configuration discussed in <CIT>, the hollow member needs to be disposed while avoiding the drive gear train. In a configuration where the drive gear train is tightly arranged with no extra space, there is a concern that providing the hollow member increases the size of the apparatus. In recent years, there has been a growing demand for more compact apparatuses. Document <CIT> discloses an image forming apparatus wherein the power source board is arranged at a lower side on the back side of the main body of the image forming apparatus and the load control board is arranged at an upper side in a vertical direction of the power source board in such a manner that the load control board does not overlap with the power source board.

The present invention is directed to preventing an increase in size of an apparatus.

According to an aspect of the present invention, there is provided an image forming apparatus as specified in claims <NUM> to <NUM>.

An overview of an image forming apparatus according to a first embodiment will be described below with reference to <FIG> is a schematic view illustrating an internal structure of the image forming apparatus according to the first embodiment of the present invention. In the following description, the image forming apparatus will be described by particularly taking an electrophotographic monochromatic laser beam printer as an example.

In the following description, in a case where an image forming apparatus A is installed on a horizontal surface, the height direction (vertical direction) of the image forming apparatus A is the Z direction. The direction that intersects with the Z direction and is parallel to the axial direction (main scanning direction) of a photosensitive drum <NUM> (described below) is the X direction. The direction intersecting with the X and Z directions is the Y direction. Desirably, the X, Y, and Z directions perpendicularly intersect with each other. For convenience, the positive and negative sides in the X direction are referred to as the right and left sides, respectively, the positive and negative sides in the Y direction are referred to as the front and back sides, respectively, and the positive and negative sides in the Z direction are referred to as the upper and lower sides, respectively.

As illustrated in <FIG>, an apparatus body <NUM> of the image forming apparatus A includes a process cartridge <NUM>. The process cartridge <NUM> includes a photosensitive drum <NUM>, a charge roller <NUM>, and a developing roller <NUM> and is attachable to and detachable from the apparatus body <NUM>. These members for image formation can be collectively replaced by replacing the process cartridge <NUM>. In image formation, the photosensitive drum <NUM> rotates, and the surface of the photosensitive drum <NUM> is charged by the charge roller <NUM>. The photosensitive drum <NUM> is irradiated with a laser beam L based on image information from an optical system (scanner) <NUM>, and an electrostatic latent image is formed on the photosensitive layer of the photosensitive drum <NUM>. The developing roller <NUM> develops the electrostatic latent image using toner to form a developer image on the photosensitive drum <NUM>.

Then, in synchronization with the formation of the developer image, a recording material S placed on a cassette <NUM> is conveyed by a pickup roller <NUM>, a feed roller pair <NUM>, a conveyance roller pair <NUM>, and a registration roller pair <NUM>. The developer image formed on the photosensitive drum <NUM> is transferred to a recording material S when a transfer roller <NUM> provided in the apparatus body <NUM> is applied with a voltage. Then, the recording material S with the developer image transferred thereto is conveyed to a fixing unit <NUM>. The fixing unit <NUM> applies heat and pressure to the recording material S while the recording material S is passing through the fixing unit <NUM> so as to fix the developer image to the recording material S. Then, the record material S with the developer image fixed thereto is discharged to a discharge tray <NUM> outside the apparatus via a discharge roller pair <NUM>.

When performing two-sided printing, an image is formed on one side of the recording material S, and then the rotational direction of the discharge roller pair <NUM> is reversed in a state where the discharge roller pair <NUM> nips the recording material S, so that the recording material S is pulled back into the apparatus body <NUM>. Then, the recording material S is conveyed to a two-sided conveying path, and then conveyed to the conveyance roller pair <NUM> again by two-sided conveyance roller pairs <NUM> and <NUM>. Thereafter, the record material S with an image formed on one side thereof is conveyed by the registration roller pair <NUM> to a nip portion formed by the photosensitive drum <NUM> and the transfer roller <NUM>, so that an image is formed on the other side of the recording material S.

A drive configuration of the image forming apparatus A will be specifically described below. <FIG> and <FIG> are perspective views illustrating the image forming apparatus A. <FIG> is a perspective view illustrating the image forming apparatus A when viewed from the left front side, and <FIG> is a perspective view illustrating the image forming apparatus A when viewed from the right front side. In <FIG> and <FIG>, exterior members are omitted.

As illustrated in <FIG> and <FIG>, the image forming apparatus A includes a right-side main body side plate <NUM> (first main body side plate) and a left-side main body side plate <NUM> (second main body side plate). The right-side main body side plate <NUM> and the left-side main body side plate <NUM> are disposed to interpose the process cartridge <NUM> between the right-side main body side plate <NUM> and the left-side main body side plate <NUM> in the X direction. In other words, the process cartridge <NUM> is disposed between the main body side plates <NUM> and <NUM> in the X direction. The main body side plates <NUM> and <NUM> each constitutes a part of the frame of the apparatus body <NUM>. The main body side plates <NUM> and <NUM> are made of metal. More specifically, the main body side plates <NUM> and <NUM> are each formed of a sheet metal.

The process cartridge <NUM> is supported by the main body side plates <NUM> and <NUM>. The main body side plates <NUM> and <NUM> each include a guide used for attaching and detaching the process cartridge <NUM> to/from the apparatus body <NUM>.

The process cartridge <NUM> is an example of an image forming unit for forming an image on the recording material S. According to the present embodiment, the process cartridge <NUM> is an image forming unit detachable from the apparatus body <NUM>. However, the image forming unit according to the present invention does not need to be detachable from the apparatus body <NUM>.

As illustrated in <FIG>, a control board <NUM> is disposed on the side opposite to the side where the process cartridge <NUM> is disposed across the left-side main body side plate <NUM>, i.e., the control board <NUM> is disposed on the outside of the main body side plate <NUM>. More specifically, the main body side plate <NUM> is disposed between the control board <NUM> and the process cartridge <NUM>. This also means that the main body side plate <NUM> is disposed between the control board <NUM> and the main body side plate <NUM>. A Central Processing Unit (CPU) <NUM> is mounted on the control board <NUM>. A guide hole <NUM> is formed on the main body side plate <NUM>. Cables <NUM> extending from the control board <NUM> pass through the guide hole <NUM> and are guided from the outside to the inside of the main body side plate <NUM>. The CPU <NUM> transmits control signals to clutches (described below) via the cable <NUM> to control the image formation on the recording material S and the conveyance of the recording material S.

As illustrated in <FIG>, a drive side plate <NUM> is disposed on the side opposite to the side where the process cartridge <NUM> is disposed across the right-side main body side plate <NUM>, i.e., the drive side plate <NUM> is disposed on the outside of the main body side plate <NUM>. More specifically, the main body side plate <NUM> is disposed between the drive side plate <NUM> and the process cartridge <NUM>. This also means that the main body side plate <NUM> is disposed between the drive side plate <NUM> and the main body side plate <NUM>. The drive side plate <NUM> is attached to the main body side plate <NUM> with screws such that a drive gear train <NUM> (described below) is interposed between the drive side plate <NUM> and the main body side plate <NUM>. A guide hole <NUM> is formed on the main body side plate <NUM>. Cables <NUM> connected with the cables <NUM> pass through the guide hole <NUM> and are guided from the inside to the outside of the main body side plate <NUM>. The cables <NUM> are guided by a cable guide <NUM> (described below) and then connected with a drive unit such as clutches. The drive side plate <NUM> is made of metal. More specifically, the drive side plate <NUM> is formed of a sheet metal.

As illustrated in <FIG>, the drive side plate <NUM> is bent to form an attachment portion 23b to be attached to the main body side plate <NUM>. According to the present embodiment, the drive side plate <NUM> has a plurality of attachment portions 23b.

In the region between the right-side main body side plate <NUM> and the left-side main body side plate <NUM>, there may be separately provided guide members (not illustrated) for holding the cables <NUM> and <NUM> and relay substrates (not illustrated) connected with the cables <NUM> and <NUM>.

<FIG> is a side view illustrating the image forming apparatus A when viewed from the right side. The drive gear train <NUM> includes a plurality of rotary gears <NUM>. According to the embodiment, the drive gear train <NUM> only needs to include at least one rotary gear <NUM>. The rotary gears <NUM> each rotate about a rotational shaft <NUM> and transmit a driving force to another gear. As described below, the rotational shafts <NUM> extend in the X direction. This means that the direction of the rotational shafts <NUM> is the X direction. In other words, the rotational axis direction of the rotary gears <NUM> is the X direction. The drive gear train <NUM> is disposed between the main body side plate <NUM> and the drive side plate <NUM>. Since the drive side plate <NUM> is attached to the main body side plate <NUM> to cover the drive gear train <NUM> from the outside, portions hidden behind the drive side plate <NUM> are drawn with dotted lines.

The main body side plate <NUM> includes a side wall 31a that extends in a direction intersecting with the X direction (desirably, in a direction perpendicularly intersecting with the X direction). The main body side plate <NUM> includes a side wall 21a that extends in a direction intersecting with the X direction (desirably, in a direction perpendicularly intersecting with the X direction). Further, the drive side plate <NUM> includes an opposite wall 23a that extends in a direction intersecting with the X direction (desirably, in a direction perpendicularly intersecting with the X direction).

The side walls 31a and 21a face each other, and the side wall 21a and the opposite wall 23a face each other in the X direction. The drive side plate <NUM> is attached to the side wall 21a and supported by the side wall 21a. More specifically, the attachment portions 23b of the drive side plate <NUM> extend from the opposite wall 23a in the X direction, and the attachment portions 23b are fixed to the side wall 21a.

One ends of the rotational shafts <NUM> are supported by the main body side plate <NUM>, and the other ends of the rotational shafts <NUM> are supported by the drive side plate <NUM> in the X direction. More specifically, one ends of the rotational shafts <NUM> are supported by the side wall 21a, and the other ends of the rotational shafts <NUM> are supported by the opposite wall 23a.

The cables <NUM> guided from the inside to the outside of the main body side plate <NUM> via the guide hole <NUM> are further guided by the cable guide <NUM> in the region between the main body side plate <NUM> and the drive side plate <NUM>. The cable guide <NUM> is disposed between the drive side plate <NUM> and the main body side plate <NUM>. More specifically, the cable guide <NUM> is disposed between the opposite wall 23a and the side wall 21a. As described in detail below, the cable guide <NUM> is attached to the drive side plate <NUM> and guides the cables <NUM> along the surface of the drive side plate <NUM>.

<FIG> is a cross-sectional view illustrating part of the drive unit of the image forming apparatus A. As illustrated in <FIG>, the drive gear train <NUM>, the cables <NUM>, and the cable guide <NUM> are disposed between the main body side plate <NUM> and the drive side plate <NUM> in the X direction. As described earlier, the cable guide <NUM> is supported by the drive side plate <NUM>. The image forming apparatus A further includes a cover member <NUM> disposed on the outside of the drive side plate <NUM> (positive side of the X direction), and the cover member <NUM> constitutes a part of the exterior of the image forming apparatus A. More specifically, the drive side plate <NUM> is disposed between the cover member <NUM> and the main body side plate <NUM> in the X direction.

As illustrated in <FIG>, the rotary gears <NUM> of the drive gear train <NUM> are disposed between the opposite wall 23a and the side wall 21a. It can be said that a space for storing the rotary gears <NUM> of the drive gear train <NUM> is formed between the opposite wall 23a and the side wall 21a. The distance between the opposite wall 23a and the cover member <NUM> is shorter than the distance between the opposite wall 23a and the side wall 21a in the X direction.

The main body side plate <NUM> is provided with a rotational shaft (first rotational shaft) <NUM> for supporting a rotary gear 29a (first rotary gear). More specifically, the drive gear train <NUM> is supported by the main body side plate <NUM>. The rotational shaft <NUM> extends in the direction perpendicular to the surface of the main body side plate <NUM>, i.e., in the X direction. The cable guide <NUM> is disposed farther on the positive side of the X direction than the rotary gear 29a, and is disposed at a position avoiding the rotational shaft <NUM>. The size of the rotational shaft <NUM> in the X direction is larger than the size of the rotary gear 29a in the X direction, and the cable guide <NUM> is disposed in the extra space. A part of the rotary gear 29a overlaps with the cable guide <NUM> when viewed in the X direction.

The drive gear train <NUM> also includes another rotary gear 29b (second rotary gear) having a larger size in the X direction than the rotary gear 29a. When viewed in the direction perpendicularly intersecting with the X direction, a region R1 of the rotary gear 29b projected on the X axis (virtual axis) extending in the X direction partly overlaps with a region R2 of the cable guide <NUM> projected on the X axis. In other words, the region (R1) where the rotary gear 29b exists at least partly overlaps with the region (R2) where the cable guide <NUM> exists in the X direction. This can prevent an increase in size of the image forming apparatus A in the X direction. A rotational shaft <NUM> supporting the rotary gear 29b can be also referred to as a second rotational shaft.

<FIG> is a side view illustrating the configuration in the side view in <FIG>, with the drive side plate <NUM> omitted. As illustrated in <FIG>, the drive gear train <NUM> includes two electromagnetic clutches 22a and 22b configured to transmit the driving force of a motor (not illustrated) to downstream side gears when the electromagnetic clutches 22a and 22b are ON and configured to not transmit the driving force to the downstream side gears when the electromagnetic clutches 22a and 22b are OFF. The two electromagnetic clutches 22a and 22b include electromagnetic clutch connectors 22a1 and 22b1, respectively, to be connected with the cables <NUM>. The cables <NUM> include two cables 24a and 24b, and the cables 24a and 24b are connected with the electromagnetic clutches 22a and 22b, respectively. One ends of the cables 24a and 24b are provided with cable connectors 24a1 and 24b1 for connection with the electromagnetic clutch connectors 22a1 and 22b1, respectively. The other ends of the cables 24a and 24b on the side opposite to the side where the cable connectors 24a1 and 24b1 are provided are provided with cable connectors 24a2 and 24b2, respectively, for connection with the cables <NUM> disposed on the inside of the main body side plate <NUM>.

As illustrated in <FIG>, when viewed in the X direction, the straight line connecting one end of the cable 24a (cable connector 24a1) and the other end thereof (cable connector 24a2), and the straight line connecting one end of the cable 24b (cable connector 24b1) and the other end thereof (cable connector 24b2) each overlap with the opposite wall 23a of the drive side plate <NUM>. When viewed in the X direction, the straight line connecting the cable connectors 24a1 and 24b1 also overlaps with the opposite wall 23a of the drive side plate <NUM>. The straight line connecting the cable connectors 24a1 and 24a2, the straight line connecting the cable connectors 24b1 and 24b2, and the straight line connecting the cable connectors 24a1 and 24b1 each overlap with the rotary gears <NUM>.

The cable guide <NUM> is disposed between the rotational shafts <NUM> in a direction perpendicularly intersecting with the direction of the rotational shafts <NUM> of the rotary gears <NUM>. When viewed in the X direction, the cable guide <NUM> is disposed between the plurality of rotary gears <NUM> (the plurality of gears) of the drive gear train <NUM>. When viewed in the X direction, the cable guide <NUM> is disposed between the plurality of rotational shafts <NUM>. As illustrated in <FIG>, the cable connectors 24a1, 24b1, 24a2, and 24b2 are disposed at positions not covered by the drive side plate <NUM> so that they are connectable even after the drive side plate <NUM> is attached to the main body side plate <NUM>. The cable connectors 24a1, 24b1, 24a2, and 24b2 are collectively referred to as cable connecting portions. The CPU <NUM> transmits control signals to the electromagnetic clutches 22a and 22b via the cables <NUM> and <NUM> to turn the electromagnetic clutches 22a and 22b ON and OFF.

According to the embodiment, the electromagnetic clutch 22a is used to change the rotational direction of the discharge roller pair <NUM>, and the electromagnetic clutch 22b is used to switch between the drive and non-drive states of the two-sided conveyance roller pairs <NUM> and <NUM>. However, control targets of the electromagnetic clutches 22a and 22b are not limited thereto. Members related to the image formation on the recording material S and the conveyance of the recording material S may be subjected to control.

In the configuration according to the present embodiment, when viewed in the direction of the rotational shafts <NUM> of the rotary gears <NUM> included in drive gear train <NUM> (when viewed in the X direction) as illustrated in <FIG>, the drive gear train <NUM> and the cable guide <NUM> partly overlap with each other. However, the cable guide <NUM> is disposed at the position avoiding the rotational shafts <NUM>. Effectively utilizing the space between the main body side plate <NUM> and the drive side plate <NUM> in this way can prevent an increase in size of the image forming apparatus A.

A configuration of the cable guide <NUM> will be specifically described below. <FIG> is a perspective view illustrating the cable guide <NUM> with the cables <NUM> installed. <FIG> is a perspective view illustrating the drive side plate <NUM> with the cable guide <NUM> attached. <FIG> is a perspective view illustrating the drive side plate <NUM> with the drive gear train <NUM> superimposed thereon.

As illustrated in <FIG>, the cable guide <NUM> guides the two cables 24a and 24b, and the cables 24a and 24b are separated from each other at a branch point 25a of the cable guide <NUM>.

The branch point 25a of the cable guide <NUM> is disposed between the rotational shafts <NUM> of the rotary gears <NUM> included in drive gear train <NUM>. The cables <NUM> are held inside the cable guide <NUM> and guided not to come into contact with the drive gear train <NUM>.

As illustrated in <FIG>, the cable guide <NUM> is attached to the drive side plate <NUM>. Since the cables <NUM> are covered by the cable guide <NUM> and the drive side plate <NUM>, the cables <NUM> are guided not to come into contact with the drive gear train <NUM>. Further, the cable guide <NUM> includes protruding portions 25b1 to 25b4 extending in the direction parallel to the rotational shafts <NUM> of the rotary gears <NUM> included in drive gear train <NUM>.

As illustrated in <FIG>, the protruding portions 25b1 to 25b4 of the cable guide <NUM> project in the direction parallel to the rotational shaft <NUM> and is disposed between the rotary gears <NUM> included in the drive gear train <NUM>. When the drive side plate <NUM> is attached to the main body side plate <NUM>, the protruding portions 25b1 to 25b4 are configured to come into contact with the main body side plate <NUM>. This leads to improvement in the rigidity of the drive side plate <NUM> and also can prevent the drive side plate <NUM> from being deformed when it is applied with a force from the outside of the cover member <NUM> at the time of shipment of the image forming apparatus A. This also leads to prevention of issues, such as detachment of the rotary gears <NUM> included in the drive gear train <NUM> from the rotational shafts <NUM> due to deformation of the drive side plate <NUM>.

According to the present embodiment, devising the wiring configuration of the cables around the drive gear train makes it possible to prevent an increase in size of the apparatus.

Further, in the configuration according to the present embodiment, the cables <NUM> and the cable guide <NUM> are connected with the shortest path without making a detour on the outside of the drive side plate <NUM>. This makes it possible to minimize the sizes of the cables <NUM> and the cable guide <NUM>, thus providing low-cost image forming apparatuses.

According to the present embodiment, the cable guide <NUM> mounted on the drive side plate <NUM> comes into contact with the main body side plate <NUM> via the protruding portions 25b1 to 25b4, whereby deformation of the main body side plate <NUM> and the drive side plate <NUM> can be prevented in a situation where a large external force is applied thereto at the time of shipment.

Although the above-described embodiment has been described based on the electrophotographic image forming apparatus A, the image forming apparatus A is not limited to an electrophotographic image forming apparatus. The present invention is also applicable to image forming apparatuses employing different printing methods such as ink-jet and offset printing methods.

Although, in the above-described embodiment, the cables <NUM> guided by the cable guide <NUM> are configured to transmit control signals from the CPU <NUM>, the configuration of the cables <NUM> is not limited thereto. The present invention is also applicable to a configuration for guiding a power supply cable extending from a power supply board and other cables.

According to the present invention, it is possible to prevent an increase in size of an apparatus.

Claim 1:
An image forming apparatus comprising:
a first main body side plate (<NUM>);
a second main body side plate (<NUM>), the first and the second main body side plates being disposed so that image forming means (<NUM>) for forming an image on a recording material is interposed between the first and the second main body side plates;
a drive side plate (<NUM>) attached to the first main body side plate (<NUM>);
a drive gear train (<NUM>), the drive gear train being disposed on a side opposite to a side where the image forming means is disposed across the first main body side plate (<NUM>), the drive gear train being disposed between the drive side plate (<NUM>) and the first main body side plate (<NUM>); and
a cable guide (<NUM>) configured to guide a cable (<NUM>), the cable guide being disposed between the first main body side plate (<NUM>) and the drive side plate (<NUM>),
wherein the drive gear train (<NUM>) includes a rotary gear (<NUM>) configured to rotate, and the cable guide (<NUM>) is disposed so that the cable guide overlaps with a part of the rotary gear when viewed in a rotational axis direction of the rotary gear.