JP3143533B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which can be vertically divided.

[0002]

2. Description of the Related Art Conventionally, in a clamshell type image forming apparatus, a rotation center is provided on a paper feeding side, that is, an upstream side in a direction in which a recording material passes, and a fixing device side is greatly opened to prevent a jam processing or the like. There are some that perform maintenance such as cleaning and replacement. In the main body device having such a configuration, the fixing device is left in the lower main body when the fixing device is opened, the upper unit of the fixing device is connected to the upper main body, the lower unit of the fixing device is connected to the lower main body, and the paper passing portion is separated. There is one that is divided and opened. Such a split type image forming apparatus is, in particular,
This is effective when a fixing device including a fixed low heat capacity heating element and a heat-resistant thin fixing film fed at substantially the same speed as the recording material is provided. In other words, the film-type fixing device hardly wraps the recording material on the upper side, whereas the film-type fixing device generates wrapping on the lower pressure roller, as compared with the conventional heat roller-type fixing device. Because it may Further, there is a possibility that the fixing thin film may be broken by a user by mistake during jam processing, and it is extremely effective to use a clamshell type in which the fixing device is divided into upper and lower main bodies and opened.

Next, a conventional film-type fixing device will be described. This fixing device includes a fixed low-heat-capacity heating element, a heat-resistant thin fixing film fed at substantially the same speed as the recording material, a pressing member, and the like. Since the speed at which the required temperature is reached is extremely fast, there is a feature that a so-called wait time is not required from the time when the power is turned on until copying is enabled. As a heating element of these fixing devices, 0.3 to
Using a 2.0 mm alumina plate as a substrate, printing a resistor such as silver-palladium alloy or ruthenium oxide on it,
Further, a ceramic heater coated with a glass thereon is used. A thermistor is in contact with the back surface of the ceramic heater for temperature control.

By the way, conventionally, in order to efficiently heat the paper, the ceramic heater is bonded to a heat-resistant resin, for example, PPS, PEEK, a liquid crystal polymer or the like, or fixed by other methods on the side opposite to the paper passing side, that is, the back side. And to prevent heat from escaping in the direction of the back surface.

[0005]

However, according to the above conventional examples, there are the following problems. First, in the case of a clamshell type image forming apparatus, a jam occurs particularly when the apparatus is used continuously, and when the clamshell type main body is opened, a part of the fixing device remaining in the lower main body. Was so hot that it could burn if touched accidentally. In particular, when removing jammed paper in the vicinity of the fixing device, it is possible to attach a label around it to call attention, but if you try to remove jammed paper in another place, such as the paper feeding unit, touch it carelessly. There was a possibility of getting burned.

Next, in a film-type fixing device, when this fixing device is applied to a high-speed image forming apparatus, the temperature of the heater surface is raised to a temperature higher than normal in a shorter time than usual. It is necessary to make it. That is, in a high-speed apparatus, the time from the start of the operation of the main body apparatus to the time when the recording material enters the fixing device is shortened.
It is necessary to raise the temperature of the fixing device to a temperature required for fixing in a short time, and the time for the recording material to pass through the fixing device is shortened. Therefore, the temperature is increased and the recording material is supplied to the recording material per unit time. This is because it is necessary to secure a sufficient amount of heat to maintain a predetermined fixing property.

To achieve this goal, a method of increasing the input power to the heater is conceivable. However, the power that can be taken out of the household outlet is limited, which is not desirable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a clamshell type image forming apparatus which can solve the above problems and can safely remove paper without causing burns during jam processing.

[0009]

[0010]

According to the present invention, the object is to provide a heating member which presses against each other and sandwiches and conveys a recording material.
A pressing member, and the pressing member in the conveying direction of the recording material.
Guides the movement of the recording materials provided on the upstream and downstream sides.
The main body of the apparatus has an upper portion with respect to the lower body.
The main body can be opened and closed, and the heating member is attached to the upper main body,
The pressure members are respectively attached to the lower body,
When the upper body is opened, the heating member and the pressure
In the image forming apparatus in which the member is divided at the boundary of the recording material conveyance path, when the upper main body is opened , the pressing member is
This is achieved by being adapted to move downward .

[0011]

[0012]

[0013]

According to the present invention, when the upper body is opened,
The pressure member moves downward. Therefore, the pressing member is
Guarded by security means. As a result, in particular, heat
Since the pressure member retracts, the guide means around it also become heated.
And the safety against heat can be further improved.

[0014]

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1> First, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view of an image forming apparatus embodying the present invention. This apparatus is an electrophotographic copying machine and has a clamshell type main body structure which is divided into upper and lower parts, and shows a state in which the upper and lower main parts are opened when replacing a process cartridge or removing jammed paper or the like. .

This apparatus comprises an optical device 1 for illuminating a document to guide it onto a photosensitive drum, a process cartridge 2 for forming an electrophotographic image, a paper feed cassette 4, a transport section 6, a fixing device 16, and the like. The upper unit of the fixing device 16 includes:
Heating body 15, fixing thin film 13, upper discharge roller 12
And the upper unit is attached to the upper body. On the other hand, the pressure roller 7, the entrance guide 9, the separation guide 10, the lower discharge roller 11, and the like are attached to the lower body. The fixing device 16 includes a heating element 15 composed of a fixed heating element having a low heat capacity, a fixing film 13 fed at substantially the same speed as a recording material such as paper to be fixed, and a fixing film 1.
3 is a film-type fixing device including a driving roller for rotating the roller 3 and a guide member for applying tension to the fixing film.

The main body as described above has a structure in which the upper main body rotates about the hinge shaft 3 to open when removing jammed paper or replacing the process cartridge. In addition, the upper body is urged with a torsion bar (not shown) or the like to help open the upper body. Further, when closed, a hook (not shown) is provided to maintain the state.

Further, the above-mentioned apparatus is provided with a pressure roller shutter 8 in the lower main body of the fixing device as a member that best shows the features of the present invention. This pressure roller shutter 8
Uses heat-resistant engineering plastics with low thermal conductivity. For example, PPS, PBT, liquid crystal polymer and the like are used. When the upper main body of the main unit shown in FIG. 1 is open, the pressure roller shutter 8 covers the exposed portion of the pressure roller 7 and is attached to the shaft of the pressure roller shutter 8. The torsion coil spring 17 is urged in the counterclockwise direction in FIG. In the state shown in FIG. 1, the pressure roller shutter 8 comes into contact with the separation guide 10 and stops.

Next, the operation when actually performing the jam processing will be described. FIG. 2 shows the state of the main body during the image forming operation, in which the upper main body is closed. If a jam occurs during use of the main unit in this state, a jam lamp is lit to notify the user. The user releases the hook (not shown) and opens the upper body. At this time, the upper body can be opened with a light force by the torsion bar (not shown) of the hinge shaft portion, and the opened state is maintained. On the other hand, the pressure roller shutter 8, which has been prevented from rotating counterclockwise by the torsion coil spring 17 by the engagement rod 14 at the end of the fixing device, covers the exposed portion of the pressure roller 7 by opening the upper body. Thus, it rotates counterclockwise and stops at the position as shown in FIG.

As described above, according to the present invention, during normal use, that is, when the upper body is closed, the shutter is retracted, and when the upper body is opened, the exposed portion of the pressure roller is removed. It is configured to be covered with a shutter.

In addition to this structure, a similar shutter is provided in the upper unit of the fixing device 16 to protect the fixing film 13 and prevent a user from being burned. At this time, the exposed portion of the upper unit may be covered.

<Embodiment 2> Next, Embodiment 2 of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

In the first embodiment, the pressure roller shutter is provided so as to cover the pressure roller. However, the pressure roller 7 may be covered by the separation guide 10 which is a guide of the sheet discharging section. FIG. 3 shows a state in which the upper main body is opened, and the separation guide 10 rotates clockwise from a position indicated by a two-dot chain line indicating that the upper main body is closed, and covers the pressure roller 7. I have. Note that the mechanism for moving the upper body in accordance with the opening and closing of the upper body is exactly the same as that of the first embodiment (not shown). As in the first embodiment, the separation guide 10 is made of an inexpensive engineering plastic having a low thermal conductivity.

According to this configuration, a desired effect can be obtained without providing a pressure roller shutter as a separate member. Further, when removing the jammed paper wound around the pressure roller, there is a gap between the jammed paper and the paper discharge roller, and the paper can be easily removed.

<Embodiment 3> Next, Embodiment 3 of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

In the second embodiment, the pressure roller is covered by the separation guide on the paper discharge side. However, the pressure roller may be covered by the entrance guide. FIG. 4 shows a state in which the upper body is opened, and the entrance guide 9 is shifted leftward by a link mechanism from a position indicated by a two-dot chain line indicating that the upper body is closed. Is covered. The mechanism for moving the upper body in accordance with the opening and closing of the upper body is the same as that of the second embodiment. Further, also in this configuration, the entrance guide material uses an engineering plastic such as PPS, PBT, or a liquid crystal polymer.

According to this configuration, similarly to the second embodiment, it is possible to prevent a user from touching the pressure roller without separately providing a separate member. Also, the jammed paper wound around the pressure roller has a space between itself and the conveyance unit 6, so that it can be easily removed. In addition, in the case of Example 2, the separation guide comes in contact with paper or the like immediately after fixing, resulting in a considerably high temperature.
In this configuration, the temperature of the entrance guide that covers the pressure roller does not rise so much, so that the effect is further enhanced.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

In the above three embodiments, the pressure roller is completely covered. However, guard members are provided on both sides of the pressure roller, and the pressure roller is inadvertently touched. It may not be necessary.

FIG. 5 shows a state in which the upper body is opened. The separation guide 10 moves upward by the force of the compression spring 20, and the entrance guide 9 also moves upward by the force of the compression spring 21. are doing. As a result, the pressure roller 7 has a shape in which both sides are guarded, and the user does not inadvertently touch the pressure roller. FIG. 6 shows a state in which the upper main body is closed, and the separation guide 10 and the entrance guide 9 are respectively pushed down by the positioning rods 18 and 19 of the upper unit portion of the fixing device of the upper main body, and are positioned at predetermined positions. ing.

According to this configuration, in addition to the necessity of a separate member, the jammed paper wrapped around the pressure roller 7 can be removed by the user, if necessary, by the separation guide 10 or the entrance guide 9.
It is possible to remove jammed paper by pressing down by hand.

Fifth Embodiment Next, a fifth embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted. Example 4
In the above, the guard members protrude on both sides of the pressure roller when the upper body is opened, but when the upper body is opened, the pressure roller is substantially lowered and guarded by the separation guide or the entrance guide. It may be configured.

FIG. 7 shows a state in which the upper body is opened. The pressure roller 7 is attached to a lever 24,
The lever 24 is rotatable about a fulcrum shaft 23. A tension spring 22 is attached to one end of the lever, and urges the lever clockwise. At the opposite end of the lever there is a receiving part for the engaging rod 14.

As shown in FIG. 7, when the upper body is opened,
The tension spring 22 rotates the lever 24 clockwise, and the pressure roller 7 falls down. At this time, the separation guide 10 and the entrance guide 9 serve as guard members, so that the user does not accidentally touch the pressure roller. FIG. 8 shows a state in which the upper body is closed.
4 contacts the end of the lever 23 to position the pressure roller 7.

By employing this configuration, the same effects as in the fourth embodiment can be obtained. Further, the jammed paper that has been wound around the pressure roller can be easily seen from the user, and the processing is easy.

Although the embodiments have been described with respect to the case where the hinge shaft is provided in the vicinity of the paper feeding unit, the present invention is not limited to this. The invention can be applied. That is, any case can be used as long as the upper and lower units can be divided into upper and lower units and the fixing unit is separated by a paper passing line as a boundary.

In each embodiment, the configuration in which the pressure roller is covered by the respective cover members has been described.
A high-temperature portion around, for example, side plates or stays made of metal may be covered in the same manner.

Embodiment 6 Next, Embodiment 6 of the present invention will be described with reference to FIGS. In the present embodiment, FIG.
As shown in FIG. 1, the present invention is applied to a fixing device of an endless belt type used in an electrophotographic image forming apparatus. FIG. 10 is a sectional view of an electrophotographic copying machine to which the fixing device of the present embodiment is attached.

In the apparatus shown in FIG. 10, when the recording material P in the tray T is fed by the feed roller 107, an image formed on the photosensitive drum by a known electrophotographic method is transferred by the transfer charger 109. The image is transferred onto the recording material P, and the recording material P is sent to the fixing device 111 by the transport belt 110.

The fixing device 111 has a structure as shown in FIG. 9. The toner on the recording material P that has reached the fixing device 111 is heated by a heating body 116 via a fixing endless belt 112, and at the same time, The toner is pressed and fixed by the pressure roller 113. Thereafter, the recording material P is discharged by the discharge roller pair 123 and stacked on the discharge tray 122.

Next, the fixing device 111 will be described with reference to FIG.
This will be described in detail with reference to FIG. Endless fixing belt 112
Has a thickness of usually 15 to 100 μm and is made of a heat-resistant resin, for example, a film of PI (polyimide), and its surface is coated with a fluororesin having good releasability. Drive and rotate. The surface of the drive roller 114 is baked with silicone rubber or the like so as to generate a sufficient frictional force in order to surely transmit the drive to the fixing endless belt 112 without slipping. On the other hand, the fixing endless belt 11
Belt 112 so that sufficient tension is applied to
Is hung on a driven roller 115 and is tensioned by a spring (not shown). Usually, the surface of the driven roller 115 is made of a material having a lower coefficient of friction than the surface of the drive roller 114, such as stainless steel or aluminum, so that no extra force is generated between the driven roller 114 and the driven roller 115.

The heating element 116 includes a stay 118 and a holder 1
21; a heater 117;
12 and is fixedly arranged so as to abut. Also,
A pressure roller 113 is disposed below the heating element 116 so as to face the heating element 116. The pressure roller 113 is pressed by a heating element 126 via a belt 112 by a spring (not shown). I have. The stay 118 is provided with a pressure roller 113.
It has a role as a structural member so as not to cause a large bending even when receiving the pressing force. On the other hand, the heater 117
A resistor 128 is printed and formed on an alumina substrate 126 having a thickness of about 2.0 mm as a base, and a glass protective layer having a thickness of about 5 to 50 μm is further coated thereon. The holder 121 has a role of insulating and supporting the heat of the heater and also serves as a guide for the belt 112. Usually the holder is PP made of heat-resistant resin
It is made of S, PEEK, liquid crystal polymer and the like.

The most characteristic point of the present invention is that a space 122 as an air layer exists between the back surface of the heater 117 and the holder 121. And this space 12
A thermistor 120 is disposed in the heater 2 as a temperature detecting element for controlling the temperature of the heater 117 to a predetermined temperature so as to contact the heater 117. In order to quickly and reliably detect the temperature of the heater, the thermistor 120 is connected to the heater 11.
7 is bonded with a silicone adhesive having good heat conductivity.

Next, a fixing process in the fixing device having the above configuration will be described. FIG. 11 is a detailed view of the vicinity of the heating element of the fixing device. When the image forming apparatus starts operating,
For example, in the case of a copier, a copy button is pressed, and in the case of a printer or a facsimile, a signal is input.
Electricity starts to flow through the resistor 128 on the drive 17, and at the same time, the drive roller 114 shown in FIG. 11 is rotated by the drive source, and the endless belt 112 starts to advance. The heat generated by the resistor 128 passes through the rear surface of the heater 117 and the glass protective layer, and is transmitted in both directions of the running endless belt 112. Heater 1
When the temperature of the back surface of 17 increases, the temperature of the thermistor 120 also increases, and the resistance value changes, and the temperature is detected. Here, the back side of the heater 117 is well insulated by the air in the space 122 as described above. For example,
When the conventional heat-resistant resin PPS is in direct contact with the entire surface of the heater 117, the thermal conductivity of engineering plastic such as PPS is 0.2 to 0.4 [W / m · k], whereas the air layer is It is 0.03 [W / m · k], indicating an overwhelmingly good heat insulating property. As a result, heat other than the heat transmitted in the direction of the endless belt 112, that is, the loss is reduced, and a predetermined fixing property can be obtained with a correspondingly smaller input power.

Embodiment 7 Next, Embodiment 7 of the present invention will be described with reference to FIG. The same parts as in the sixth embodiment are denoted by the same reference numerals, and the description is omitted.

In the sixth embodiment, an air layer is provided by providing a groove or a dent in the holder in contact with the back surface of the heater. However, the present invention is not limited to this.
As shown in FIG. 2, the holder may be completely penetrated.

In this embodiment, the holder 121 on the periphery of the back surface of the resistor 128 on the heater 117 is a completely hollow hole, and the back surface of the heater is a stay 129 via an air layer. . The stay 129 is a metal block containing aluminum as a main component. If aluminum is used for the stay, the thermal conductivity will be about 4 to 6 times that of a normal steel bent type stay, and if continuous use results in a significant temperature distribution in the depth direction in the figure, this will be reduced. And can be reduced.

That is, when the fixing device is not warmed up, the air layer in the space 122 functions as a good heat insulating layer when the fixing device is not warmed up. It has the effect of leveling the distribution. This is effective in, for example, eliminating the non-sheet-passing portion temperature rise that occurs when thick and small-sized paper such as a postcard is passed. Further, in the present invention, the stay 129 is not always necessary, and may be configured as a structure with a heater and a holder, for example. In this case, only the air layer is on the back side of the heater.

[0050]

As described above, the present invention provides an image forming method
When the upper body of the forming device is opened, the pressing member moves downward.
When the upper body is opened, pressurizing
The members can be guarded by guide means, especially
Guide means around the retracted pressure member
Is also less likely to be heated, increasing safety against heat
The effect that can be obtained.

[0051]

[Brief description of the drawings]

FIG. 1 is a sectional view of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view when the device in FIG. 1 is in a closed state.

FIG. 3 is a sectional view of an image forming apparatus according to a second embodiment of the present invention.

FIG. 4 is a sectional view of an image forming apparatus according to a third embodiment of the present invention.

FIG. 5 is a sectional view of an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 6 is a cross-sectional view when the device is in a closed state.

FIG. 7 is a sectional view of an image forming apparatus according to a fifth embodiment of the present invention.

8 is a cross-sectional view when the device in FIG. 7 is in a closed state.

FIG. 9 is a sectional view of a fixing device according to a sixth embodiment of the present invention.

FIG. 10 is a cross-sectional view of the image forming apparatus equipped with the apparatus in FIG. 9;

FIG. 11 is a detailed cross-sectional view around a heating body of the apparatus in FIG. 9;

FIG. 12 is a detailed cross-sectional view around a heating body according to a seventh embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 7 pressure roller (pressure member) 8 pressure roller shutter (shutter member) 9 entrance guide (guard member) 10 paper discharge guide (guard member) 15 heating element (heating member) 16 fixing device 112 fixing endless belt (fixing thin) 113) Pressure roller (pressing member) 114 Drive roller (supporting roller) 115 Driven roller (supporting roller) 117 Heater (heating element) 121 Holder (support) 122 Space

Claims (1)

(57) [Claims] 1. A heating device in which a recording material is pressed against each other and sandwiched and conveyed.
And the pressing member in the conveying direction of the recording material.
Move the recording materials provided upstream and downstream of the pressure member.
And a guide means for guiding, and the apparatus main body is attached to the lower main body.
The upper body can be opened and closed, and the heating member is
The pressure member is attached to the lower body
When the upper body is opened, the heating member
In the image forming apparatus in which the pressing member is divided by a recording material conveyance path, when the upper main body is opened , the pressing member moves downward. apparatus.