JP2014006435A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of compactification, effectively retaining temperature restriction for an image forming section or a toner cleaning device with high safety from outside access.SOLUTION: An image forming apparatus is characterized by: heat shielding between a fixing device 7 and an image forming section 2d by providing a heat shielding device 8 in between the fixing device and an image forming section of the image forming apparatus; having air current made capable of flowing by forming an air current path A by the heat shielding device 8, the image forming section 2d and a toner cleaning device 6 with a fan in the air current path A; having the heat shielding device 8 include an opening section 21 opened toward the fixing device and also working as a duct for the cooled air to the fixing device, opening the opening section and a duct inlet section along with an opening action of an opening/closing cover 9, and closing an opening section and the inlet section of the duct when the opening/closing cover is closed.

Description

  The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus is known as an electronic copying machine, an optical printer, a facsimile machine, a plotter, an MFP having a composite function of these, and the like.

  Image formation in such an image forming apparatus is performed by the following electrophotographic process.

  That is, an electrostatic latent image is formed by uniform charging and exposure of the photosensitive member, and a toner image is formed by developing the electrostatic latent image.

  The formed toner image is transferred to a sheet-like recording medium such as transfer paper or an overhead projector OHP sheet, and is thermally fixed to the sheet-like recording medium by a fixing device.

  The sheet-like recording medium on which the toner image is heat-fixed is discharged out of the image forming apparatus.

  In the image forming process described above, a portion “one or more toner images are formed on one or more photoconductors by an electrophotographic process” is referred to as an “image forming portion”.

  The image forming apparatus has one or more photoconductors in the image forming unit. When two or more photoreceptors are used, a “toner image having a different color” is formed for each photoreceptor.

  These multi-color toner images are transferred and fixed in a superimposed manner on the same sheet-like recording medium to form a multicolor image or a color image.

  The “image forming apparatus” includes a transfer device, a fixing device, a toner cleaning device and the like in addition to the image forming unit.

  The “transfer device” is a device that transfers one or more toner images formed on the image forming unit to a sheet-like recording medium.

  There are two types of transfer apparatuses: a direct transfer type that directly transfers a toner image from one or more photoconductors of an image forming unit to a sheet-like recording medium, and an intermediate transfer type.

In the intermediate transfer system, an intermediate transfer belt is generally used, and a toner image is transferred from the photoreceptor to the intermediate transfer belt, and further transferred from the intermediate transfer belt to a sheet-like recording medium.
The “fixing device” is a device that heat-fixes the toner image transferred to the sheet-like recording medium onto the sheet-like recording medium.

  The “toner cleaning device” is a device that removes “transfer residual toner” that has not been transferred to the sheet-like recording medium from the transfer device.

“Temperature constraints” exist in the image forming unit and these various apparatuses.
That is, the image forming apparatus and the various apparatuses described above must be placed in an appropriate temperature range in order to properly perform their functions.

  For example, the fixing device needs to be maintained at “a high temperature necessary for thermally fixing the toner image”.

  On the other hand, when the temperature of the optical system that performs exposure exceeds the appropriate range, the function of the optical system is deteriorated and the image forming unit cannot perform proper exposure.

  Further, when the temperature of the developing portion exceeds the appropriate range, proper development is hindered.

  In the toner cleaning device, when the temperature rises, “transfer residual toner” remaining in the transfer device is melted and solidified, making it difficult to clean.

  Alternatively, as the temperature of the space including the transfer residual toner rises, the air in the space thermally expands, causing the transfer residual toner to scatter to the image forming apparatus main body, causing the image to be formed to be contaminated.

The “appropriate temperature due to temperature constraints” of the various apparatuses included in the image forming apparatus is different from that of the fixing apparatus in other portions.
If the heat from the fixing device held at a high temperature is transmitted to various devices and raises the temperature of these devices, the temperature constraint of the various devices is broken, which adversely affects image formation.
Therefore, a “fan that allows air current to flow inside and outside the image forming apparatus main body” is usually provided, and air heated in the vicinity of the fixing device is discharged so as not to accumulate in the image forming apparatus main body.

  Alternatively, “cooling air” is sent into the apparatus from the outside of the image forming apparatus to prevent the temperature of various apparatuses from rising.

On the other hand, the temperature of the fixing device must always be maintained at a fixing temperature.
In general, an image forming apparatus has an “opening / closing cover that opens and closes with respect to the apparatus main body” so that the inside of the apparatus can be accessed.

  For example, when the transfer paper that is a sheet-like recording medium is jammed in the apparatus, it is necessary to access the inside of the apparatus in order to remove the jammed transfer paper.

  In such a case, if an operator carelessly touches the “high temperature fixing device”, there is a risk of burns.

  It has been widely known that an air flow is generated in the image forming apparatus main body, hot air in the apparatus main body is discharged to the outside of the apparatus, and “temperature suppression of various apparatuses is suppressed” by cooling air from the outside.

  For example, Patent Document 1 discloses an image forming apparatus that can prevent an increase in the temperature of an image forming unit and a toner cleaning device around a fixing device.

  However, when “the fixing device and the image forming unit and the toner cleaning device are arranged close to each other”, the space is occupied by “only the function of the duct” in the conventional configuration.

For this reason, it is difficult to dispose various devices in the image forming apparatus, and it is not easy to make the image forming apparatus compact.
Further, when a user or an operator accesses the inside of the apparatus, it takes a long time for the temperature of the heat fixing apparatus to cool down to “a temperature at which no burns occur”, and the workability is poor.

  The present invention has been made in view of the above-described circumstances.

  That is, it is an object of the present invention to realize an image forming apparatus that can be made compact, can effectively hold the temperature constraints of the image forming unit and the toner cleaning device, and has high safety of external access.

  The image forming apparatus according to the present invention records an image forming unit for forming one or more toner images on one or more photoconductors and one or more toner images formed on the image forming unit by electrophotographic process. A transfer device for transferring to a medium, a fixing device for thermally fixing the toner image transferred to the sheet-like recording medium to the sheet-like recording medium, and a transfer residual toner that has not been transferred to the sheet-like recording medium are removed from the transfer device. In an image forming apparatus comprising: a toner cleaning device to be opened; an opening and closing cover that opens and closes to the apparatus main body so as to allow access to the inside of the apparatus main body; A heat shield device made of a material having a high thermal conductivity and a low thermal conductivity is provided between the fixing device and the image forming unit to shield heat between the fixing device and the image forming unit. An air flow path is formed by the heat shield device, the image forming unit, and the toner cleaning device, and the air flow can be circulated by the fan in the air flow path. The heat shield device has an opening that opens toward the fixing device, and is fixed. A switching plate that opens and closes the inlet of the duct, and an interlocking mechanism that interlocks opening and closing of the switching plate and the opening with the opening and closing operation of the opening and closing cover. Along with the opening operation, the interlocking mechanism opens the opening and the inlet of the duct, and when the open / close cover is closed, the opening and the inlet of the duct are closed.

  In the image forming apparatus of the present invention, the heat between the fixing device and the image forming unit is shielded by the heat shield device, so that the heat of the fixing device is not easily transmitted to the image forming unit.

The “air flow path” through which the air flow can be circulated by the fan is formed by the heat shield device, the image forming unit, and the toner cleaning device, and does not require a dedicated member for forming the air flow path.
Since the heat shield device, the image forming unit, and the toner cleaning device are arranged close to each other for forming the air flow path, it is possible to measure the compactness of the image forming device.

  By the airflow flowing through the airflow path, the air in the path is discharged outside the apparatus, or the temperature in the path can be lowered by the air from the outside of the apparatus.

  For this reason, the “temperature constraint” of the image forming unit and the toner cleaning device forming part of the air flow path can be maintained well.

  The heat shield also serves as a “duct for the cooling airflow to the fixing device”, and the interlocking mechanism opens and closes the switching plate and the opening in conjunction with opening and closing of the opening and closing cover.

  Therefore, when the opening / closing cover is opened, the entrance and opening of the duct are opened, and the cooling airflow quickly cools the fixing device. Therefore, when the user or the operator accesses the inside of the device, the temperature of the heat fixing device is “not burned”. The time for cooling to “temperature” can be shortened, and workability can be improved.

1 is a diagram illustrating an example of an image forming apparatus. It is a figure which shows a heat shield and its periphery. It is a figure explaining the duct part in a heat shield. It is a figure explaining the state which opened and closed the opening / closing cover. It is a figure explaining the relationship between opening and closing of an opening-and-closing cover and a heat shield device. It is a figure explaining the relationship between opening / closing of an opening-and-closing cover and the interlocking mechanism of a heat shield. It is a figure explaining the airflow in an airflow path | route. FIG. 6 is a diagram illustrating an air flow for cooling the fixing device.

Hereinafter, embodiments will be described.
FIG. 1 is an explanatory view showing an example of an image forming apparatus to which the present invention is applied as viewed from the lateral direction.

  In FIG. 1, reference numerals 1a to 1d denote "exposure apparatuses", reference numerals 2a to 2d denote "image forming process units", and reference numerals 3a to 3d denote "photosensitive members".

Reference numeral 4 denotes an “intermediate transfer belt”, reference numeral 5 denotes a “secondary transfer roller”, reference numeral 6 denotes a “toner cleaning device”, and reference numeral 7 denotes a “fixing device”.
Reference numeral 8 denotes a “heat shield device”, and reference numeral 9 denotes an “open / close cover”. FIG. 1 shows a state in which the opening / closing cover 9 is opened to allow access to the inside.

  The exposure apparatuses 1a to 1d, the image forming process units 2a to 2d, and the photoconductors 3a to 3d constitute an “image forming unit”.

  The image forming process units 2a to 2d include a charger that uniformly charges the photoreceptors 3a to 3d, a developing device, and a cleaning device.

  When image formation is performed, the photoreceptors 3a to 3d are uniformly charged by the chargers of the image forming process units 2a to 2d.

  The uniformly charged photoreceptors 3a to 3d are image-exposed by corresponding exposure devices 1a to 1d to form electrostatic latent images.

The electrostatic latent images formed on the photoconductors 3a to 3d are respectively developed by the developing devices included in the image forming process units 2a to 2d, and toner images are formed for each photoconductor.
A specific example will be described.

  The “electrostatic latent image corresponding to the yellow image component” is formed on the photoconductor 3d, and this electrostatic latent image is developed with “yellow toner” to form a yellow toner image on the photoconductor 3d.

  An “electrostatic latent image corresponding to a magenta image component” is formed on the photoconductor 3c, and this electrostatic latent image is developed with “magenta toner”, and a magenta toner image is formed on the photoconductor 3c.

  The “electrostatic latent image corresponding to the cyan image component” is formed on the photoconductor 3b, and this electrostatic latent image is developed with “cyan toner” to form a cyan toner image on the photoconductor 3d.

  The “electrostatic latent image corresponding to the black image component” is formed on the photoconductor 3a, and this electrostatic latent image is developed with “black toner” to form a black toner image on the photoconductor 3c.

  In the image forming process, the photoreceptors 3a to 3d are rotated counterclockwise, and the intermediate transfer belt 4 is rotated clockwise.

  The color toner images formed on the photoreceptors 3d to 3a are sequentially primary-transferred onto the intermediate transfer belt 4 by a primary transfer member (not shown).

  That is, first, a yellow toner image is transferred, and a magenta toner image, a cyan toner image, and a black toner image are sequentially transferred so as to overlap therewith.

  These four color toner images overlap with each other on the intermediate transfer belt 4 to form a “color toner image”.

  The transfer paper P normally used as a sheet-like recording medium is stacked and stored in a cassette provided below the apparatus.

  When a color toner image is transferred, the uppermost sheet is fed and sent to the secondary transfer portion, that is, the contact portion between the intermediate transfer belt 4 and the secondary transfer roller 5 at a timing.

  The color toner image on the intermediate transfer belt 4 is secondarily transferred from the intermediate transfer belt 4 onto the transfer paper P by the secondary transfer roller 5.

  The transfer paper P onto which the color image has been transferred is then sent to the fixing device 7 where the color toner image is fixed in the fixing device 7 and discharged out of the image forming apparatus.

  During the secondary transfer, “transfer residual toner” remaining on the intermediate transfer belt 4 without being transferred onto the transfer paper P is removed from the intermediate transfer belt 4 by the toner cleaning device 6.

That is, the image forming apparatus shown in FIG. 1 has an image forming unit that forms toner images on one or more photoconductors 3a to 3d by an electrophotographic process.
In addition, transfer devices 4 and 5 that transfer the toner image formed on the image forming unit to the sheet-like recording medium P are provided.
Further, the image forming apparatus includes a fixing device 7 that thermally fixes the toner image transferred to the sheet-like recording medium P to the sheet-like recording medium P.
In addition, a toner cleaning device 6 that removes untransferred toner that has not been transferred to the sheet-like recording medium P from the transfer device 4 is provided.
Further, a heat shield 8 is provided between the fixing device 7 and the image forming unit so as to shield the heat of the fixing device 7.

  And it has the opening / closing cover 9 which opens and closes with respect to an apparatus main body, and enables access to the inside of an apparatus main body at the time of opening.

  FIG. 2 is an enlarged view of “the part indicated by the symbol Z (the part surrounded by a broken line)” in FIG.

  As shown in FIG. 2, the heat shield device 8 is disposed between the fixing device 7 and the image forming unit (the image forming process unit 2d).

  As a part of the heat shield device 8, a heat insulating material 15 such as a sponge is attached to the side of the heat shield device 8 that is in contact with the image forming process unit 2d to fill the gap between the two.

In FIG. 2, the part indicated by the symbol A is an “air flow path”.
The air flow path A is formed as a “long space in a direction perpendicular to the drawing” surrounded by the heat shield device 8, the toner cleaning device 6, and the image forming unit (the image forming process unit 2d).

  The heat shield 8 is made of “a material having high heat resistance and low heat conduction” so that the heat transferred from the fixing device 7 is reduced.

  When the material of the heat shield device 8 is, for example, “heat resistant resin material”, the effect of shielding the heat of the fixing device 7 is high.

  Therefore, the temperature rise of the image forming unit 2d and the toner cleaning device 6 can be effectively suppressed.

An air flow is formed by a fan, which will be described later, in the air flow path A surrounded by the heat shield device 8, the image forming unit 2d, and the toner cleaning device 6, thereby preventing "heat accumulation in the air flow path A".
Further, the image forming unit 2d and the toner cleaning device 6 can be cooled by this air flow.

  FIG. 3 shows a state where the toner cleaning device 6, the fixing device 7, and the heat shield device 8 are viewed from the Y direction in FIG.

The heat shield 8 removes the surface on the image forming unit side to show “the inside of the duct part”.
As shown in FIG. 3, a pulley 10, a guide rail 11, a spring 12, a wire 13, and a switching plate 14 are disposed in a portion constituting the “duct” of the heat shield device 8 (upper portion of the toner cleaning device 6). Is provided.

  With reference to FIGS. 4-8, the relationship between the state of these each part and opening / closing of the opening-and-closing cover 9 is demonstrated.

  The configuration of the image forming apparatus is the same as that shown in FIG.

  Therefore, in FIGS. 4 to 8 related to the following description, only parts necessary for the description are denoted by reference numerals.

  4A shows a state in which the opening / closing cover 9 is opened, and FIG. 4B shows a state in which the opening / closing cover 9 is closed.

One end of a wire 13 shown in FIG. 3 is fixed to the opening / closing cover 9.
When the opening / closing cover 9 is opened, the wire 13 is pulled out by the opening operation of the opening / closing cover 9 and becomes as shown in FIG.

  When the open / close cover 9 is closed, as shown in FIG. 4B, the wire 13 is pulled into the apparatus main body.

  FIGS. 5A and 5B show the states shown in FIGS. 4A and 4B as “perspective perspective views”.

  In FIG. 5A showing the open / close cover 9 in the opened state, the wire 13 is drawn out. In FIG. 5B showing the closed state, the wire 13 is drawn into the apparatus main body.

  The operation of the wire 13 and the like accompanying the opening / closing of the opening / closing cover 9 will be described with reference to FIGS. 6 (a) and 6 (b).

FIG. 6B shows a state in which the opening / closing cover 9 is closed.
A wire 13 is wound around the pulley 10, one end of the wire 13 is fixed to a stationary member of the heat shield 8, and the other end is fixed to an opening / closing cover 9 not shown in FIG. 6.
One end of a tension spring 12 is also fixed to the pulley 10. The other end of the spring 12 is fixed to a “back immovable member” of the heat shield 8.

When the opening / closing cover 9 is opened, the wire 13 is pulled by the opening / closing cover 9 and moves toward the left in FIG. 6B according to the opening operation.
As shown in FIG. 6, a switching plate 14 is provided on the duct entrance side of the heat shield device 8 in the portion constituting the duct.
As shown in FIG. 6B, the switching plate 14 is configured to “rotate clockwise and counterclockwise around the swing axis”.
When the opening / closing cover 9 is closed, the switching plate 14 closes the inlet of the duct as shown in FIG.

When the opening / closing cover 9 is opened, the pulley 10 moves to the left from the state of FIG.
A cover member 22 is also integrated with the pulley 10 so as to be displaced together with the pulley 10.

The movement of the pulley 10 is performed along the guide rail 11 against the pulling force of the spring 12.
As shown in FIG. 6A, the guide rail 11 is provided with an opening 21, and the opening 21 is opened toward the fixing device 7.

When the opening / closing cover 9 is closed, the opening 21 is closed by the lid member 22.
When the pulley 10 moves as described above and the lid member 22 moves together with the pulley 10, the opening 21 is opened as shown in FIG.

  When the opening / closing cover 9 is “opened”, the pulley 10 is displaced to the position shown in FIG.

At this time, the switching plate 14 is rotated counterclockwise by an appropriate mechanism (not shown), and as shown in FIG. 6A, the inlet portion of the duct (the left end portion in the drawing) is opened.
At the same time, the opening 21 opens.

  That is, the heat shield device 8 has an opening 21 that opens toward the fixing device 7, and also serves as a duct for the cooling airflow to the fixing device 7.

  Then, as shown in FIG. 6A, when the inlet portion of the duct is opened and the opening 21 is opened, a “duct for cooling airflow to the fixing device” is formed.

  When closing the opening / closing cover 9, the spring 12 pulls the pulley 10 and the lid member 22 in accordance with the closing operation, and the lid member 22 closes the opening 21.

  Further, the switching plate 14 rotates clockwise from the state shown in FIG. 6A, and closes the inlet of the duct as shown in FIG. 6B.

  That is, a mechanism (not shown) that opens and closes the pulley 10, the guide rail 11, the spring 12, the wire 13, and the switching plate 14 constitutes the above-described "interlocking mechanism".

  FIG. 7 shows a state of “the airflow C in the airflow path (portion indicated by“ A ”in FIG. 2)” when the opening / closing cover 9 is closed.

  In the state of FIG. 7, since the opening / closing cover 9 is closed, the “part constituting the duct” in the heat shield 8 is closed together with the switching plate 14 and the opening 21.

At this time, when the fan 20 is operated and “the air inside the apparatus main body is discharged outside the apparatus”, as shown in FIGS. 7A and 7B, an air flow C passing through the air flow path is generated.
The air flow C discharges “warm air” in the air flow path outside the apparatus, and cools the heat shield 8, the image forming unit (image forming process unit), and the toner cleaning device 6.

  In this way, the “temperature constraints” of these devices are well maintained.

  FIG. 8 is a diagram illustrating a state of the cooling airflow B in a state where the opening / closing cover 9 is opened.

  When the opening / closing cover 9 is opened, the inlet of the duct of the heat shield device 8 by the switching plate 14 is opened, and the opening 21 is also opened.

Thereby, a “cooling airflow passage” in the duct is formed.
At this time, the fan 20 sends “cooling air from the outside of the apparatus main body” into the apparatus.
Note that the “back side of the duct (the fan 20 side)” in the heat shield device is structurally “open toward the fan 20”.

  When the fan 20 is operated as described above, the cooling air sent by the fan 20 becomes the air flow B and flows from the opening 21 toward the fixing device 7 to cool the fixing device 7.

  At this time, “low temperature air outside the apparatus” also flows from the opened duct inlet, and also flows as airflow B from the opening 21 toward the fixing device 7 to cool the fixing device 7.

  The opening / closing cover 9 is opened when access to the inside of the image forming apparatus is required, but the fixing device 7 is cooled well as described above.

  Accordingly, it is possible to shorten the cooling time until the temperature of the heat fixing device 7 is “a temperature at which no burns occur”, and workability is improved.

  With the above configuration, the image forming apparatus can be made compact by disposing the image forming unit 2d having the “temperature constraint” and the toner cleaning device 6 in the vicinity of the fixing device 7.

  In addition, the image forming unit and the toner cleaning device can be sufficiently cooled, and temperature constraints can be maintained.

  Further, when the worker accesses the fixing device 7 or the like, the “time until the fixing device 7 is cooled to a temperature at which the fixing device 7 is not burned” can be shortened.

  Although not shown in FIGS. 1 to 8, the heat shield 8 can have a “function of fixing the open / close cover 9 to the apparatus main body when the open / close cover 9 is closed”.

  For example, a lock claw can be provided on the opening / closing cover 9 side, and the heat shield device 8 can be provided with a “holding mechanism for locking the lock claw”.

  Thus, the heat shield device 8 can be provided with functions other than the original functions of the heat shield device, which can contribute to the compactness of the image forming apparatus.

  In the above embodiment, the effects of opening and closing the inlet of the duct portion of the heat shield device with the switching plate 14 and the case of not using the switching plate 14 (when the inlet is always open) were compared.

  That is, the “velocity and heat transfer coefficient of the airflow flowing through the airflow path A” in the case where the switching plate 14 is used and in the case where the switching plate 14 is not used are compared by the thermal airflow simulation.

  The opening / closing cover is in a “closed state”.

The results were as follows.
Wind speed Heat transfer coefficient
Without switching plate 14 F H
With switching plate 14 1.35F 1.27H.

  Thus, with respect to the wind speed: F and heat transfer coefficient: H in the absence of the switching plate 14, the wind speed with the switching plate 14 is 1.35 times, and the heat transfer coefficient is 1.27 times. .

  By closing the switching plate 14, the “air cross-sectional area” becomes substantially close to the cross-sectional area of the air flow path 1 </ b> A, and the flow rate is increased accordingly, and the improvement of the heat transfer coefficient is reduced.

  That is, by using the switching plate 14, the cooling effect of the image forming units 2 a to 2 d and the toner cleaning device 6 is enhanced.

2d Image forming section image forming process section
6 Toner cleaning device
7 Fixing device
8 Heat shield
9 Opening and closing cover
10 pulley
12 Spring
13 wires

Japanese Patent No. 4174119

Claims (4)

An image forming unit that forms one or more toner images on one or more photoconductors by an electrophotographic process, and a transfer device that transfers the one or more toner images formed on the image forming unit to a sheet-like recording medium A fixing device that thermally fixes the toner image transferred to the sheet-like recording medium to the sheet-like recording medium; and toner cleaning that removes untransferred toner that has not been transferred to the sheet-like recording medium from the transfer device. In an image forming apparatus, comprising: an apparatus; an opening / closing cover that opens and closes to the apparatus main body so as to allow access to the inside of the apparatus main body when opened;
A heat shield device made of a material having high heat resistance and low thermal conductivity is provided between the fixing device and the image forming unit to shield heat between the fixing device and the image forming unit. ,
An air flow path is formed by the heat shield device, the image forming unit, and the toner cleaning device, and the air flow can be circulated by the fan in the air flow path.
The heat shield device has an opening that opens toward the fixing device, serves also as a duct for the cooling airflow to the fixing device, and opens and closes an opening portion of the duct, and an opening / closing operation of the opening / closing cover And an interlocking mechanism that interlocks opening and closing of the switching plate and the opening,
Along with the opening operation of the opening / closing cover, the interlock mechanism opens the opening and the inlet of the duct, and when the opening / closing cover is closed, the opening and the inlet of the duct are closed. Image forming apparatus. The image forming apparatus according to claim 1.
An image forming apparatus, wherein the interlock mechanism of the heat shield device includes a member that applies a force to the opening / closing cover in a direction to close the opening / closing cover. The image forming apparatus according to claim 1 or 2,
The interlocking mechanism of the heat shield device includes a wire fixed at one end side to the open / close cover and the other end to a stationary member of the heat shield device, a pulley around which the wire is wound, and the rear of the duct with respect to the pulley. An image forming apparatus comprising a tension spring member that applies a pulling force to the side. The image forming apparatus according to any one of claims 1 to 3,
An image forming apparatus, wherein the heat shield has a function of fixing the open / close cover to the apparatus main body when the open / close cover is closed.

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