Image forming apparatus having first and second grounding routes

An image forming apparatus includes a cassette attaching section, a media cassette, a loading plate and a first and second ground conducting route. The cassette attaching section includes a media supplying roller for supplying media. The media cassette is attachably and removably installed in the cassette attaching section. The loading plate is mounted in the media cassette and loads the media stacked up in the media cassette. The first ground conducting route makes static electricity discharge from the loading plate to a grounding portion of the cassette attaching section when the media cassette is attached to the cassette attaching section. The second ground conducting route conducts with the media and makes static electricity discharge to the grounding portion when a distance between the media supplying roller and the media is shortened after the first ground conducting route is conducted.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image forming apparatus to prevent trouble caused by static electricity.

2. Description of Related Art

In some kinds of image forming apparatuses such as what uses an electrophotographic method, an electrostatic method, or a magnetoelectric method; toner images are formed on surfaces of photosensitive drums etc. based on image information received from host devices. These toner images are transcribed onto recording media supplied from media supplying units. And, these toner images are fixed with heat in fixing units, so as to form images. In the media supplying units, media contained in media cassettes are pressed to media supplying rollers, so as to be supplied. Inside of the media cassettes, loading plates to be pushed to the media supplying rollers are provided. And, the recording media are loaded on these loading plates. In these states, the loading plates with media are pushed or moved toward the media supplying rollers. Then, the recording media are pressed to the media supplying rollers. And, each medium is separated and supplied one by one by a conveying force of media supplying rollers with friction between the rolls and separating rubbers.

In the media supplying apparatus, static electricity is generated by friction such as friction between the recording medium and the media supplying roller, friction between the recording medium and the separating rubber, or friction between the recording media themselves, when the recording media are conveyed. Moreover, in some cases, static electricity is already charged on the recording medium, before the media supplying unit is attached to the image forming apparatus. Such static electricity can flow in unexpected routes. Especially, in an image forming apparatus of recent years, many component parts are made of resin. Therefore, much static electricity is likely to be generated on the recording medium loaded on a media cassette made of resin. The static electricity flowing in unexpected routes becomes a noise of electric current that causes inconvenience such as drop of graphical quality, malfunction of the apparatus, or electric shocks to operators (c.f. JP 7-237783).

Therefore, the present invention is made to remove inconvenience such as drop of graphical quality, malfunction of the apparatus, or electric shocks to operators caused by static electricity flowing in unexpected routes becoming a noise of electric current.

BRIEF SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided an image forming apparatus having: a first ground conducting route for conducting static electricity charged on a recording medium through an outer frame of a media supplying unit to a grounding point, and a second ground conducting route for conducting static electricity charged on a recording medium through a media supplying roller to a grounding point.

And in the image forming apparatus mentioned above: the first ground conducting route is formed when the media supplying unit is on a way to a position where the media supplying unit is attached to the image forming apparatus body, so as to conduct static electricity charged before the media supplying unit is attached to the image forming apparatus body; and the second ground conducting route conducts static electricity charged after the media supplying unit is attached to the image forming apparatus body.

DETAILED DESCRIPTION OF THE INVENTION

Configuration

FIG. 1is an explanatory diagram showing a chief elements of a structure (before attaching) of Embodiment 1.

FIG. 1shows a diagram of an image showing a positional relation of chief component parts only, seeing inside of an apparatus through a side wall of the apparatus' body, so as to refer to explain a structure, a function and an operation of Embodiment 1.

As shown inFIG. 1, chief component parts of Embodiment 1 are an image forming apparatus body1and a media cassette2. The image forming apparatus body1comprises a media supplying roller9, a pushing out member10, a release portion11and a conveyance path15. The media cassette2(media supplying unit) comprises a loading plate3, a conducting plate4, a pushing up member5, a plate holding portion6, an L shaped crook portion7, an outer frame8, a separating rubber12, a coil spring13and a loading plate fulcrum14.

Before explaining a structure, a function and an operation of Embodiment 1 referring toFIG. 1, overall structure and operation of an image forming apparatus to which the present invention is applied (Embodiment 1 to 4) are explained.

FIG. 2is an explanatory diagram showing an image forming apparatus.

FIG. 2shows a diagram of an image showing chief component parts only, seeing an inside of the apparatus through a side wall of the apparatus' body, so as to refer to explain an overall structure and operation of the image forming apparatus to which the present invention is applied.

As shown inFIG. 2, a pile of recording media20are contained in a media cassette2. Each of recording media20are supplied by a combination of a media supplying roller9and a separating rubber12one by one from the media cassette2to a conveyance path15. Then, a static electricity is generated by frictions such as a friction between each of recording media20and a media supplying roller9, a friction between each of recording media20and a separating rubber12, and a friction between recording media20themselves. And, how to discharge this static electricity is a subject of the present invention.

Each of recording media20supplied to a conveyance path15separated one by one, are sensed by an intake sensor21. After that, each of recording media20are sent by a resist roller22to a conveying belt23which is a portion of the conveyance path15. When each of recording media20pass at a halfway point sensor37, an image forming section36starts forming a toner image. This toner image is transcribed by a transcribing roller24to each of recording media20conveyed on a conveying belt23.

Formation of a toner image inside of the image forming section36, is performed as follows. A surface of a photosensitive drum25rotating in a direction shown by an arrow, is charged negative by a charging roller26. When this negative charged portion comes to a position under an exposing head27, the exposing head27radiates light, so as to form electrostatic latent image at the charged portion based on an image data. This electrostatic latent image is developed by a developing roller29provided in a developer28, so as to be a toner image. This toner image is transcribed by a transcribing roller24to one of recording media20. Then, toner remained on the surface of the photosensitive drum25is removed by a cleaning unit30.

The toner image transcribed by the transcribing roller24to one of recording media20, is fixed with a treatment of high temperature and high pressure by a heating roller31and a backup roller32. The one of recording media20on which a toner image is fixed, is let out by an outlet roller33onto a medium stack34, an outlet of the one of recording media20, is detected by an outlet sensor35.

As mentioned above, an outline of the overall structure and operation of an image forming apparatus, has been explained. And, the chief component parts shown inFIG. 1referred to above, will be explained in detail, referring to a slant view corresponding to Embodiment 1.

FIG. 3is a slant viewed diagram showing a media cassette and its attaching portion of Embodiment 1.

FIG. 3shows a slant view of a media cassette and a slant view of a portion of an image forming apparatus body where the media cassette is attached.

When a user is going to detach the media cassette2from the image forming apparatus body1, he touches his hand to a handle42. Then, the handle42rotates around a handle fulcrum43which is supporting the handle42. And, a latch41is taken off. Then, the media cassette2is pushed out by a pushing out member10provided in the image forming apparatus body1.

A loading plate3is provided in the media cassette2. And, a pile of recording media (not shown inFIG. 3) are loaded on the loading plate3. Then, a pair of side guides44hold the recording media20(shown inFIG. 1) at longitudinal sides of them, and a tail guide46holds a lateral side of them, so as not to scatter in the media cassette2.

Thus, the recording media (not shown inFIG. 3) held in the media cassette2and loaded on the loading plate3, are pressed by a pushing up member5to the media supplying roller9provided in the image forming apparatus body1, after the media cassette2is attached to the image forming apparatus body1. The loading plate3is supported by a loading plate fulcrum45, so as to rotate up and down around the loading plate fulcrum45.

FIG. 4is a slant viewed diagram showing a loading plate of Embodiment 1.

FIG. 4shows a slanted view of a backside of the loading plate3which is taken apart from the image forming apparatus body1.

As shown inFIG. 4, a loading plate3with a pile of recording media20is pressed to a media supplying roller9by a pushing up member5comprising a coil spring.

Moreover, a release frame16is made for containing a force of a pushing up member5by engaging a plate holding portion6with an L shaped crook portion7formed on the backside of the loading plate3, when the media cassette2is not attached to the image forming apparatus body1. Here, the release frame16with the plate holding portion6is provided at a prescribed portion of an outer frame (shown inFIG. 3). When the media cassette2is attached to the image forming apparatus body1, a release portion11formed on an inner base of the image forming apparatus body1(shown inFIG. 1) releases the engagement between the plate holding portion6and the L shaped crook portion7, with pressing a coil spring13.

Returning toFIG. 1, a function and an operation of Embodiment 1 will be described.

As shown inFIG. 1, the recording media20are loaded on the loading plate3piling up on it. The recording media20are held by a pair of side guides44(FIG. 3) at longitudinal sides. And, they are held by a tail guide46at a lateral side. Thus, they do not scatter in the media cassette2. InFIG. 1, a force of a pushing up member5is contained by engaging a plate holding portion6with an L shaped crook portion7formed on the backside of the loading plate3, as the media cassette2is not attached to the image forming apparatus body1.

A conducting plate4is provided, so that one end portion of it contacts with at least either of said recording medium20or said loading plate3and that other end of it is projected to outside of the media cassette2.

FIG. 5is an explanatory diagram showing a chief elements of a structure (a first state of combination) of Embodiment 1.

FIG. 5shows a state that a conducting plate4of the media cassette2contacts with a pushing out member10of the image forming apparatus body1, when the media cassette2is on a way to a position where the media cassette2is attached to the image forming apparatus body1(a first state of combination).

In the first state of combination, a first ground conducting route comprising the recording media20, the loading plate3, the conducting member4and the pushing out member10; is formed. A static electricity already charged before the attachment, on a recording medium or in the media cassette including the loading plate3, is discharged through the first ground conducting route to a grounding point100.

FIG. 6is an explanatory diagram showing a chief elements of a structure (a second state of combination) of Embodiment 1.

FIG. 6shows a state that a plate holding portion6of the media cassette2contacts with a release portion11of the image forming apparatus body1, when the media cassette2is still on a way near to a position where the media cassette2is attached to the image forming apparatus body1(a second state of combination).

In the second state of combination, the recording media20does not contact with a media supplying roller9yet, because a force of a pushing up member5is contained by engaging a plate holding portion6with an L shaped crook portion7formed on the backside of the loading plate3.

FIG. 7is an explanatory diagram showing a chief elements of a structure (a state of a complete attachment) of Embodiment 1.

FIG. 7shows a state that the media cassette2containing the recording media20is completely attached to the image forming apparatus body1. In this state, the plate holding portion6of the media cassette2is pushed by the release portion11of the image forming apparatus body1. Then, engagement of the plate holding portion6with the L shaped crook portion7, is released. When the engagement is released, the recording media20piled and loaded on the loading plate3, is pushed by a pushing up member5up to the media supplying roller9. As a result, a second ground conducting route comprising the recording media20, the media supplying roller9, the image forming apparatus body1and a grounding point100; is formed. Here, the media supplying roller9is made up of a material such as a rubber, in which fragments of electron-conductive matter such as carbon or fila are scattered. This media supplying roller9contacts with a conductive contacting portion formed as prolonged from a prescribed portion of the image forming apparatus body1. And, the conductive contacting portion is connected to a grounding point100through a conductive portion of the image forming apparatus body1. Then, a static electricity generated in a printing operation by a friction between the recording media20and the media supplying roller9, between the recording media20and the separating rubber12, or between the recording media20themselves; and charged on a recording medium; is discharged through the second ground conducting route including the media supplying roller9, to a grounding point100.

As described above, a first ground conducting route is formed, when the media cassette2is on a way to a position where the media cassette2is attached to the image forming apparatus body1. Then, a static electricity already charged on a recording medium, is discharged through the first ground conducting route. And, a second ground conducting route is formed, when the media cassette2containing the recording media20is completely attached to the image forming apparatus body1. Then, a static electricity generated in a printing operation and charged on a recording medium existing at top of the pile of recording media20, is discharged through the media supplying roller9included in the second ground conducting route. Therefore, every static electricity charged on the media cassette2, is completely removed. And, obtained is an effect of eliminating inconveniences such as drop of graphical quality, malfunction of the apparatus, or electric shocks to operators; which are caused by a static electricity flowing in unexpected routes as a noise of electric current.

In the description mentioned above, a first ground conducting route comprises the recording media20, the loading plate3, the conducting member4and the pushing out member10leading to a grounding point100. However, the present invention is not limited to this example. That is, a static electricity to be discharged, is not limited to a static electricity charged on the recording media20or on the loading plate3. But, a static electricity charged on every element in the media cassette2, is a subject of the present invention. Therefore, a first ground conducting route can comprise all the conducting route that that is grounded through the pushing out member10, when the media cassette2is on a way to a position where the media cassette2is attached to the image forming apparatus body1. For example, a first ground conducting route can comprise the pushing up member5or the plate holding portion6, and the loading plate3, the conducting member4and the pushing out member10leading to a grounding point100.

Moreover, in the description mentioned above, a first ground conducting route is formed, when the media cassette2is on a way to a position where the media cassette2is attached to the image forming apparatus body1. However, the present invention does not limit a position of forming a first ground conducting route. That is, a first ground conducting route is continuously formed after the media cassette2is completely attached to the image forming apparatus body1. And, a static electricity generated in a printing operation and charged on a recording medium existing at top of the pile of recording media20, is discharged not only through the second ground conducting route but also through the first ground conducting route.

Configuration

FIG. 8is an explanatory diagram showing a chief elements of a structure (before attaching) of Embodiment 2.

FIG. 8shows a diagram of an image showing a positional relation of chief component parts only, seeing inside of an apparatus through a side wall of the apparatus' body, so as to refer to explain a structure, a function and an operation of Embodiment 2.

As shown inFIG. 8, chief component parts of Embodiment 2 are an image forming apparatus body51and a media cassette52. The image forming apparatus body51comprises a media supplying roller9, a release portion11and a conveyance path15. The media cassette52(media supplying unit) comprises a loading plate3, a pushing up member55, a plate holding portion6, an L shaped crook portion7, an outer frame58, a separating rubber12, a coil spring13, a loading plate fulcrum14and a projecting portion54.

Chief component parts shown inFIG. 8, will be described in detail, referring toFIG. 9. The component parts in Embodiment 2 same as Embodiment 1, are designated with the same number as Embodiment 1.

FIG. 9is a slant viewed diagram showing a media cassette and its attaching portion of Embodiment 2.

FIG. 9shows a slant view of a media cassette and a slant view of a portion of an image forming apparatus body where the media cassette is attached.

A loading plate3is provided in the media cassette52. And, a pile of recording media (not shown inFIG. 9) are loaded on the loading plate3. Then, a pair of side guides44hold the recording media20(shown inFIG. 8) at longitudinal sides of them, and a tail guide46holds a lateral side of them, so as not to scatter in the media cassette52.

Thus, the recording media (not shown inFIG. 9) held in the media cassette52and loaded on the loading plate3, are pressed by a pushing up member55to the media supplying roller9provided in the image forming apparatus body51, after the media cassette52is attached to the image forming apparatus body51. The loading plate3is supported by a loading plate fulcrum45, so as to rotate up and down around the loading plate fulcrum45formed at a prescribed portion of an outer frame58. The outer frame58is formed by a mold with resin.

FIG. 10is a slant viewed diagram showing a loading plate of Embodiment 2.

FIG. 10shows a slanted view of a backside of the loading plate3which is taken apart from the image forming apparatus body51.

As shown inFIG. 10, a loading plate3with a pile of recording media20is pressed to a media supplying roller9by a pushing up member55comprising a coil spring. A projecting member54is formed at an end of the pushing up member55. The projecting member54contacts with a metal plate56shown inFIG. 9provided on an inner base of the outer frame58. Thus, a static electricity charged on the recording media flows to the projecting portion54.

Moreover, a release frame16is made for containing a force of a pushing up member55by engaging a plate holding portion6with an L shaped crook portion7formed on the backside of the loading plate3, when the media cassette52is not attached to the image forming apparatus body51. Here, the release frame16with the plate holding portion6is provided at a prescribed portion of an outer frame (shown inFIG. 9). When the media cassette52is attached to the image forming apparatus body51, a release portion11formed on an inner base of the image forming apparatus body51(shown inFIG. 8) releases the engagement between the plate holding portion6and the L shaped crook portion7, with pressing a coil spring13.

Returning toFIG. 8, a function and an operation of Embodiment 2 will be described.

As shown inFIG. 8, the recording media20are loaded on the loading plate3piling up on it. The recording media20are held by a pair of side guides44(FIG. 9) at longitudinal sides. And, they are held by a tail guide46at a lateral side. Thus, they do not scatter in the media cassette52. InFIG. 8, a force of a pushing up member55is contained by engaging a plate holding portion6with an L shaped crook portion7formed on the backside of the loading plate3, as the media cassette52is not attached to the image forming apparatus body51.

A portion of the recording media20contacts with the metal plate56.

FIG. 11is an explanatory diagram showing a chief elements of a structure (a first state of combination) of Embodiment 2.

FIG. 11shows a state that a projecting portion54of the media cassette52contacts with a release portion11of the image forming apparatus body51, when the media cassette52is on a way to a position where the media cassette52is attached to the image forming apparatus body51(a first state of combination).

In the first state of combination, a first ground conducting route comprising the recording media20, the loading plate3, the metal plate56(shown inFIG. 9), the projecting portion54and the release portion11; is formed. A static electricity already charged before the attachment, on a recording medium or in the media cassette52including the loading plate3, is discharged through the first ground conducting route to a grounding point100.

FIG. 12is an explanatory diagram showing a chief elements of a structure (a second state of combination) of Embodiment 1.

FIG. 12shows a state that a plate holding portion6of the media cassette52contacts with a release portion11of the image forming apparatus body51, when the media cassette52is still on a way near to a position where the media cassette52is attached to the image forming apparatus body51(a second state of combination).

In the second state of combination, the recording media20does not contact with a media supplying roller9yet, because a force of a pushing up member55is contained by engaging a plate holding portion6with an L shaped crook portion7formed on the backside of the loading plate3.

FIG. 13is an explanatory diagram showing a chief elements of a structure (a state of a complete attachment) of Embodiment 2.

FIG. 13shows a state that the media cassette2containing the recording media20is completely attached to the image forming apparatus body51. In this state, the plate holding portion6of the media cassette52is pushed by the release portion11of the image forming apparatus body51. Then, engagement of the plate holding portion6with the L shaped crook portion7, is released. When the engagement is released, the recording media20piled and loaded on the loading plate3, is pushed by a pushing up member55up to the media supplying roller9. As a result, a second ground conducting route comprising the recording media20, the media supplying roller9, the image forming apparatus body51and a grounding point100; is formed. Then, a static electricity generated in a printing operation by a friction between the recording media20and the media supplying roller9, between the recording media20and the separating rubber12, or between the recording media20themselves; and charged on a recording medium; is discharged through the second ground conducting route including the media supplying roller9, to a grounding point100.

As described above, Embodiment 2 obtains an effect that the number of component parts can be decreased in addition to the same effect as Embodiment 1, because a metal plate is provided on an inner base of the media cassette in Embodiment 2, instead of a conducting plate4in Embodiment 1.

Configuration

FIG. 14is an explanatory diagram showing a chief elements of a structure (before attaching) of Embodiment 3.

FIG. 14shows a diagram of an image showing a positional relation of chief component parts only, seeing inside of an apparatus through a side wall of the apparatus' body, so as to refer to explain a structure, a function and an operation of Embodiment 3.

As shown inFIG. 14, chief component parts of Embodiment 3 are an image forming apparatus body61and a media cassette62. The image forming apparatus body61comprises a media supplying roller9, a conveyance path15, a pulling up section68and a guide plate69. The pulling up section68comprises an arm plate70, an arm spring71, an arm frame72and a fulcrum portion73. The media cassette62comprises a loading plate63, an outer frame65, a separating rubber12, a loading plate fulcrum45, a catching portion66and a conducting plate67.

Chief component parts shown inFIG. 14, will be described in detail, referring toFIG. 15. The component parts in Embodiment 3 same as Embodiment 1, are designated with the same number as Embodiment 1.

FIG. 15is a slant viewed diagram showing a media cassette and its attaching portion of Embodiment 3.

FIG. 15shows a slant view of a media cassette and a slant view of a portion of an image forming apparatus body where the media cassette is attached.

A loading plate63is provided in the media cassette62. And, a pile of recording media (not shown inFIG. 15) are loaded on the loading plate63. Then, a pair of side guides44hold the recording media20(shown inFIG. 14) at longitudinal sides of them, and a tail guide46holds a lateral side of them, so as not to scatter in the media cassette62.

Thus, the recording media (not shown inFIG. 15) held in the media cassette62and loaded on the loading plate63, are pressed by a pulling up section68of the image forming apparatus body61, to the media supplying roller9provided in the image forming apparatus body61, after the media cassette62is attached to the image forming apparatus body61. The pulling up section68is provided at each of left and right side of the image forming apparatus body61. The loading plate63is supported by a loading plate fulcrum45, so as to rotate up and down around the loading plate fulcrum45formed at a prescribed portion of an outer frame65. The outer frame65is formed by a mold with resin.

FIG. 16is a slant viewed diagram showing a loading plate of Embodiment 3.

FIG. 16shows a slanted view of a backside of the loading plate63which is taken apart from the image forming apparatus body61.

As shown inFIG. 16, a loading plate63comprises an arm plate70, an arm spring71and an arm frame72. And, the loading plate63with a pile of recording media20is pressed to a media supplying roller9by a pulling up section68of the image forming apparatus body61. In the pulling up section68, an arm frame72is pushed by a catching portion66formed on both side walls of the media cassette62(c.f.FIG. 14). Then, an arm spring71is pulled, so as to rotate an arm plate70around a fulcrum portion73.

A conducting plate67comprising a conducting material of metal prolonged under the loading plate63in a direction of attaching the media cassette62, is provided in the media cassette62. An end of the conducting plate67touches a base of the loading plate63loading the recording media20(c.f.FIG. 14). The other end of the conducting plate67prolonged upward of the media cassette62, touches a guide plate69. Then, a static electricity charged on the recording media20flows to a guide plate69provided at a prescribed portion of the image forming apparatus body61. The guide plate69is made of a metal plate.

Returning toFIG. 14, a function and an operation of Embodiment 3 will be described.

As shown inFIG. 14, the recording media20are loaded on the loading plate63piling up on it. The recording media20are held by a pair of side guides44(FIG. 15) at longitudinal sides. And, they are held by a tail guide46at a lateral side. Thus, they do not scatter in the media cassette62. InFIG. 14, a force of a pulling up section68does not operate on the loading plate63, as the media cassette62is not attached to the image forming apparatus body61.

FIG. 17is an explanatory diagram showing a chief elements of a structure (a first state of combination) of Embodiment 3.

FIG. 17shows a state that a catching portion66formed on both side walls of the media cassette62contacts with an arm frame72of the pulling up section68of the image forming apparatus body61, when the media cassette62is on a way to a position where the media cassette62is attached to the image forming apparatus body61(a first state of combination).

In the first state of combination, a first ground conducting route comprising the recording media20, the loading plate63, the conducting plate67and the guide plate69; is formed. A static electricity already charged before the attachment, on a recording medium or in the media cassette62including the loading plate63, is discharged through the first ground conducting route to a grounding point100.

FIG. 18is an explanatory diagram showing a chief elements of a structure (a second state of combination) of Embodiment 2.

FIG. 18shows a state that a catching portion66formed on both side walls of the media cassette62pushes an arm frame72of the pulling up section68of the image forming apparatus body61, when the media cassette62is still on a way near to a position where the media cassette62is attached to the image forming apparatus body61. As a result, in the pulling up section68, an arm spring71is pulled, so as to begin rotating an arm plate70around a fulcrum portion73(a second state of combination).

In the second state of combination, the recording media20does not contact with a media supplying roller9yet.

FIG. 19is an explanatory diagram showing a chief elements of a structure (a state of a complete attachment) of Embodiment 3.

FIG. 19shows a state that the media cassette62containing the recording media20is completely attached to the image forming apparatus body61. In this state, in the pulling up section68, an arm spring71is pulled, so as to rotate an arm plate70around a fulcrum portion73. As a result, the recording media20piled and loaded on the loading plate63, is pulled by the pulling up section68up to the media supplying roller9. And, a second ground conducting route comprising the recording media20, the media supplying roller9, the image forming apparatus body61and a grounding point100; is formed. Then, a static electricity generated in a printing operation by a friction between the recording media20and the media supplying roller9, between the recording media20and the separating rubber12, or between the recording media20themselves; and charged on a recording medium; is discharged through the second ground conducting route including the media supplying roller9, to a grounding point100.

As described above, Embodiment 3 obtains an effect that the number of component parts can be decreased in addition to the same effect as Embodiment 1, because a pulling up section is provided at an image forming apparatus body61, and a plate holding portion6, an L shaped crook portion7, a coil spring13and a release frame16are omitted at a media cassette62in Embodiment 3.

Configuration

FIG. 20is an explanatory diagram showing a chief elements of a structure (before attaching) of Embodiment 4.

FIG. 20shows a diagram of an image showing a positional relation of chief component parts only, seeing inside of an apparatus through a side wall of the apparatus' body, so as to refer to explain a structure, a function and an operation of Embodiment 4.

As shown inFIG. 20, chief component parts of Embodiment 4 are an image forming apparatus body81and a media cassette82. The image forming apparatus body81comprises a media supplying roller9, a conveyance path15and a pulling up section68. The pulling up section68comprises an arm plate70, an arm spring71, an arm frame72and a fulcrum portion73. The media cassette62comprises a loading plate63, an outer frame65, a separating rubber12, a loading plate fulcrum45, a catching portion66and a conducting plate67.

Chief component parts shown inFIG. 20, will be described in detail, referring toFIG. 21. The component parts in Embodiment 4 same as Embodiment 1 to 3, are designated with the same number as Embodiment 1 to 3.

FIG. 21is a slant viewed diagram showing a media cassette and its attaching portion of Embodiment 4.

FIG. 21shows a slant view of a media cassette and a slant view of a portion of an image forming apparatus body where the media cassette is attached.

A loading plate63is provided in the media cassette82. And, a pile of recording media (not shown inFIG. 21) are loaded on the loading plate63. Then, a pair of side guides44hold the recording media20(shown inFIG. 20) at longitudinal sides of them, and a tail guide46holds a lateral side of them, so as not to scatter in the media cassette82.

Thus, the recording media (not shown inFIG. 21) held in the media cassette82and loaded on the loading plate63, are pressed by a pulling up section68of the image forming apparatus body61, to the media supplying roller9provided in the image forming apparatus body61, after the media cassette62is attached to the image forming apparatus body61. The loading plate63is supported by a loading plate fulcrum45, so as to rotate up and down around the loading plate fulcrum45formed at a prescribed portion of an outer frame65. The outer frame65is formed by a mold with resin.

FIG. 22is a slant viewed diagram showing a loading plate of Embodiment 4.

FIG. 22shows a slanted view of a backside of the loading plate63which is taken apart from the image forming apparatus body81.

As shown inFIG. 22, a loading plate63comprises an arm plate70, an arm spring71and an arm frame72. And, the loading plate63with a pile of recording media20is pressed to a media supplying roller9by a pulling up section68of the image forming apparatus body61. In the pulling up section68, an arm frame72is pushed by a catching portion66formed on both side walls of the media cassette62(c.f.FIG. 14). Then, an arm spring71is pulled, so as to rotate an arm plate70around a fulcrum portion73. The fulcrum portion73of the pulling up section68is connected to a grounding point100.

Returning toFIG. 20, a function and an operation of Embodiment 4 will be described.

As shown inFIG. 20, the recording media20are loaded on the loading plate63piling up on it. The recording media20are held by a pair of side guides44(FIG. 21) at longitudinal sides. And, they are held by a tail guide46at a lateral side. Thus, they do not scatter in the media cassette82. InFIG. 20, a force of a pulling up section68does not operate on the loading plate63, as the media cassette62is not attached to the image forming apparatus body61.

FIG. 23is an explanatory diagram showing a chief elements of a structure (a first state of combination) of Embodiment 4.

FIG. 23shows a state that a catching portion66formed on both side walls of the media cassette82contacts with an arm frame72of the pulling up section68of the image forming apparatus body81, when the media cassette82is on a way to a position where the media cassette82is attached to the image forming apparatus body81(a first state of combination).

In the first state of combination, a first ground conducting route comprising the recording media20, the loading plate63and the fulcrum portion73; is formed. A static electricity already charged before the attachment, on a recording medium or in the media cassette82including the loading plate63, is discharged through the first ground conducting route to a grounding point100.

FIG. 24is an explanatory diagram showing a chief elements of a structure (a second state of combination) of Embodiment 4.

FIG. 24shows a state that a catching portion66formed on both side walls of the media cassette62pushes an arm frame72of the pulling up section68of the image forming apparatus body81, when the media cassette82is still on a way near to a position where the media cassette82is attached to the image forming apparatus body81. As a result, in the pulling up section68, an arm spring71is pulled, so as to begin rotating an arm plate70around a fulcrum portion73(a second state of combination).

In the second state of combination, the recording media20does not contact with a media supplying roller9yet.

FIG. 25is an explanatory diagram showing a chief elements of a structure (a state of a complete attachment) of Embodiment 4.

FIG. 25shows a state that the media cassette82containing the recording media20is completely attached to the image forming apparatus body81. In this state, in the pulling up section68, an arm spring71is pulled, so as to rotate an arm plate70around a fulcrum portion73. As a result, the recording media20piled and loaded on the loading plate63, is pulled by the pulling up section68up to the media supplying roller9. And, a second ground conducting route comprising the recording media20, the media supplying roller9, the image forming apparatus body81and a grounding point100; is formed. Then, a static electricity generated in a printing operation by a friction between the recording media20and the media supplying roller9, between the recording media20and the separating rubber12, or between the recording media20themselves; and charged on a recording medium; is discharged through the second ground conducting route including the media supplying roller9, to a grounding point100.

As described above, Embodiment 4 obtains an effect that the number of component parts can be further decreased in addition to the same effect as Embodiment 3, because a fulcrum portion73of a pulling up section68comprises a first ground conducting route in Embodiment 4.

Incidentally, in the above Embodiments, an image forming apparatus body attached with only one media cassette was described. However, the present invention is not limited to this example. That is, the present invention can be applied to an image forming apparatus body attached with plural media cassettes.