JPH0468382A - Image forming device - Google Patents

Abstract

PURPOSE:To deal with even the occurrence of jamming without damaging a heat resistance sheet by providing a protective member protecting the heat resistance sheet, and moving the protective member to an operating position for protecting the heat resistance sheet and a nonprotective operating position. CONSTITUTION:A toner image is formed on the surface of a recording material by an image means A, and heated and fixed by a heating body via the heat resistance sheet 14 moving at the moving speed of the recording material. Since a fixing means B has the protective member 28 protecting the heat resistance sheet 14 and a protective member operating means, the protective member 28 can be moved to the protective operating and nonprotective operating positions by the protective member operating means. Thus, the maintenance and checking of the image forming device, or the releasing work of the jamming can be carried out without damaging or burning the heat resistance sheet 14.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an image forming means for forming a toner image on a recording material such as a transfer paper, and a toner image formed on the recording material by the image forming means. The present invention relates to an image forming apparatus comprising a fixing means for fixing an unfixed toner image onto a recording material by heating and melting the unfixed toner image with a heating body through a heat-resistant sheet.

[Prior Art] The general structure of a conventional image forming apparatus will be described with reference to FIG. 9. Reference numeral 1 denotes a document mounting table made of a transparent member such as glass, which scans a document by reciprocating in the direction of arrow a. A short-focus small-diameter imaging element array 2 is arranged directly below the document table.
A document image placed on a document table 1 is irradiated by an illumination lamp 3, and the reflected light image is slit-exposed onto a photosensitive tram 4 by the array 2. Furthermore, this photosensitive tram 4
rotates in the direction of the arrow. A charger 5 uniformly charges the photosensitive tram 4 coated with, for example, a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer. The photosensitive drum 4, which is uniformly charged by the charger 5, is subjected to image exposure by the element array 2, and an electrostatic latent image is formed.

This static NN image is visualized by a developing device 6 using toner made of a resin or the like that softens and melts when heated. On the other hand, the sheet or recording paper P stored in the cassette S is rotated by a pair of conveying rollers 8 that are pressed against each other in the vertical direction in synchronization with the image on the feeding roller 7 and the photosensitive tram 4. is sent onto the tram 4 by. I copied it and transcribed it.
The toner image formed on the photosensitive tram 4 by the Wr' device 9 is transferred onto the sheet P. Thereafter, the sheets 1 to P separated from the photosensitive drum 4 by a known separating means are guided to a fixing device 11 by a conveyance guide 0, subjected to heat fixing processing, and then discharged onto a tray 12.

Note that after the toner image is transferred, residual toner on the photosensitive drum 4 is removed by a cleaner 13.

Next, the fixing device 11 of this apparatus will be described in detail.

In FIG. 10, reference numeral 14 indicates a heat-resistant sheet, and reference numerals 15 and 16 indicate metal rollers, one of which is a driving roller and the other a driven roller. That is, the metal rollers 15 and 16 are supported by a side plate via sliding bearings (not shown), and a heat-resistant sheet 1 with a thickness of approximately 25 μm is placed between the rollers 15 and 16.
4 is applied with a certain amount of tension. The metal roller 16 is driven in the direction of arrow A by a gear train and a motor (not shown). On the other hand, the metal roller 15 is a driven roller, and the heat-resistant sheet 14 is rotated by a driving force determined by the friction coefficient between the metal roller 16 and the heat-resistant sheet 14 and the tension of the heat-resistant sheet 14, and the distance between the metal roller 15 and the heat-resistant sheet 14 is However, the driving force is transmitted in the same way.

Reference numeral 17 denotes a pressure roller having a metal core and a rubber surface layer, and is driven by the frictional force between it and the heat-resistant sheet 14 in the same way as the metal roller 15.

18 is a low heat capacity linear heating element fixedly supported on the side plate, and has a heat resistant and electrically insulating base material 19 made of alumina or the like.
A linear or strip-shaped resistance material 20 made of, for example, Ta2N is provided on the lower surface of the resistor. The resistive material 20 is energized from both ends in the longitudinal direction. The current is applied in a pulse-like waveform with a period of about 20 m5 ec, and the pulse width is varied to provide a pulse corresponding to the desired temperature and energy release amount controlled by the temperature measuring element 21.

Heating body 1 whose emitted energy, temperature, etc. are controlled in this way
The heat-resistant sheet 14 moves as it comes into contact with the heat-resistant sheet 8 . An example of this heat-resistant sheet is PT on the image contact side of the polyimide sheet.
Examples include endless films coated with a release layer made of a fluororesin such as FE or PAF with a conductive material added thereto.

Next, the image fixing operation of the fixing device shown in FIG. 10 will be explained.

The recording material 22, on which the unfixed toner image 24 has been transferred by the image transfer means described above, is conveyed in the direction of arrow B to the main fixing device by means such as a conveyor belt, and smoothly transferred to the heating body along the fixing population guide 23. 18 and the pressure roller 17. The toner image 24 made of heat-fusible toner on the recording material 22 is first heated by the heating element 18 via the heat-resistant sheet 14, and at least its surface layer portion is completely softened and melted.

Thereafter, the toner image 24 is separated from the heating body 18 and naturally radiates heat, cooled and solidified again, and the recording material 22 is sent along the kite member 25 and discharged from the main fixing device.

As mentioned above, since the toner is once completely softened and melted and then hardened, the cohesive force of the toner becomes very large and the toner behaves as a group. In addition, since the toner image 24 is pressed by the pressure roller 17 when it is heated, softened and melted, it penetrates into the surface layer of the recording material 220 and is cooled and solidified as it is. fixed on top.

By the way, when the recording material 22 is caught in the nip between the heating member 18 and the pressure roller 17, a problem of paper jamming may occur, and how to deal with it will be described. Pressure on the pressure roller 17 shown in FIG. 10 can be manually released by a mechanism not shown. As a result, the recording material 22 is moved to E in FIG. 11 without releasing the pressure.
If the pressure roller is pulled out in the direction and the heating body 18 is pressed again, the image forming apparatus becomes operable. Furthermore, the following configuration is also possible. The metal rollers 15, 16, the heat-resistant sheet 14,
If the upper unit 27 including the heating body 18 is configured in a so-called alligator type that can be opened and closed, in this case, when a paper jam occurs in the main body of the image forming apparatus including the fixing device, the entire upper unit 27 is opened and the inside of the main body is removed. Recording material can be removed. Note that FIG. 13 shows the upper unit in an open state.

[Problems to be Solved by the Invention] However, in the conventional example, the recording material 22 is caught between the nip between the pressure roller 17 and the heating element 18, resulting in a paper jam (hereinafter referred to as jam). When the recording material 22 is pulled out by hand, it is conceivable that the heat-resistant sheet D may be accidentally touched through the opening C or D in FIG. As a result, the following problems may occur.

(1) Since the heat-resistant sheet 14 is a thin film of approximately several tens of microns, there is a risk that it may be damaged by fingernails or the like. When the image forming apparatus is operated in this state, the recording material 22 or pressure roller 1
7 comes into direct contact with the heating body 18, which may lead to melting of the pressure roller 17, offset of the toner image 24 on the recording material 22 to the heating body, etc.

(2) Even if the heat-resistant sheet 14 is not damaged, if the heat-resistant sheet is soiled, it may cause poor separation of the recording material 22, image staining, etc.

However, since the openings C and D are necessary to ensure the conveyance path of the recording material 22 and to prevent the temperature of the fixing device from rising to some extent due to the heat of the heating element, it is impossible to completely eliminate them. .

(3) During operation of the image forming apparatus, the fixing device becomes hot due to the heat of the heating body. This also applies to the surface of the heat-resistant sheet 14, and even after the operation of the image forming apparatus has been temporarily stopped for jam removal, if you touch the heat-resistant sheet 14 with your fingers, it may cause burns.

In particular, in the conventional example shown in FIG.
It is easy to touch 4.

Therefore, the present invention provides a method for dealing with troubles such as jams, without damaging the heat-resistant sheet, even if the casing has an opening for a recording material conveyance path or a heat dissipation opening. It is an object of the present invention to provide an image forming apparatus in which users do not suffer from burns caused by heat-resistant sheets.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an image forming means for forming a toner image on a recording material such as a transfer paper, and an image forming means for forming a toner image on the recording material by the image forming means. A fixing means fixes the formed unfixed toner image onto a recording material by heating and melting the formed unfixed toner image with a heating body through a heat resistant sheet, and the fixing means further protects the heat resistant sheet. The heat resistant sheet is configured to include a protection member for protecting the heat-resistant sheet, and a protection member operating means for moving the protection member to a protection operation position for protecting the heat-resistant sheet and a non-protection operation position.

Further, in the second invention, the structure further includes a protection member moving means for automatically moving the protection member to a protection operation position when a jam of the recording material is detected,
In the third invention, a pressurizing means is further added to the first invention, and when the pressurizing means and the heating means are separated, the protective member is moved to the protective operation position in conjunction with this. configured so that The fourth invention is
The fixing means moves the protection member to the protection operation position after the recording material undergoes processing such as image transfer and fixation within the main body and is discharged from the main body, and also moves the protection member to the protection operation position immediately before the start of the above operation. The fifth invention is configured to further include a protective member operating device for moving the protective member to an operating position. a fixing means for fixing the unfixed toner image formed on the recording material by heating and melting the unfixed toner image formed on the recording material with a heating body through a heat-resistant sheet; a conveying means for conveying the bond paper from the image forming means to the fixing means, the fixing means further comprising a protective member for protecting the heat-resistant sheet, and the protective member is located at a position of the conveying means. It moves to the protective operating position in conjunction with the opening operation of the opening/closing door provided on a part of the casing.
It is provided with operation means for moving each to a non-operating position in conjunction with the closing operation.

[Function] Since the present invention includes an image forming means and an image fixing means, a toner image is first formed on the surface of a recording material by the image means. Then, the toner image is heated and fixed by a heating element via a heat-resistant sheet that moves at approximately the same speed as the recording material. According to the present invention, the fixing means further includes a protection member that protects the heat-resistant sheet and a protection member operation means, so that the protection member is moved between the protection operation position and the non-protection operation position as necessary by the protection member operation means. can be moved to. Therefore, according to the present invention, maintenance and inspection of the image forming apparatus or jam clearing work can be carried out without damaging the heat-resistant sheet or incurring burns from the sheet.

According to the second invention, the protection member moving means automatically moves the protection member to the protection operation position when a jam is detected. Therefore, the user can safely clear the jam without performing any safety operations.Furthermore, the third invention provides that when the pressurizing means and the heating means are separated, for example for maintenance and inspection, the protective member The protection member operating device of the fourth invention moves the protection member to the protection operation position when processing such as image formation and fixing is not performed, and then automatically moves the protection member to the protection operation position immediately before the processing is performed. Therefore, according to the present invention, not only can maintenance and inspection be performed safely, but also the heat-resistant sheet can be protected from dust when the image forming apparatus is not in use.

The fifth invention further includes an operating means, so that when the opening/closing door provided in the part of the casing in which the conveying means is located is opened, the protective member is moved to the protective operating position and closed. Then, it acts to move it to the non-operating position. Therefore, according to the present invention, not only jam removal in the fixing section but also maintenance and inspection of the image forming section can be carried out without touching the heat-resistant sheet.

[Embodiment] First, the entire embodiment of the image forming apparatus will be explained with reference to FIG. 1. Referring to FIG. It is easy to understand that this is substantially concave compared to the conventional one described with reference to FIG. It is also easily understood that the protective member designated by numeral 28 on the left side of the figure is different. Therefore, only the above-mentioned different parts will be explained, and the other parts will be given the same reference numerals and the explanation will be omitted.

FIG. 2 is a detailed sectional view of the fixing peripheral area of the present image forming apparatus, showing a state in which the upper unit 27 is closed, that is, in operation. A fixing upper stay 35 protects the upper part of the heat-resistant sheet 14, and has bent portions 36 at both ends in the longitudinal direction. As shown in FIGS. 3 and 4, arms 32 are attached to both ends of the upper stay around the center of rotation 29 on the bent portion of the upper stay. It's attached. Further, a gear 31a is mounted and slid coaxially with the rotation center of the arm 32, and its shaft 29 is fixed to a mounting support plate 37. Two more identical gears are also attached to the mounting support plate 37 at positions where they mesh with the gear 31a, and these gears constitute a gear train 31. In addition, a rack mounting post 33 stands just before the recording material ejection part of the bottom plate 34 that forms the lower unit for the main body upper unit 27, and a rack 30 is mounted on the top of the post at a height that meshes with the last gear of the gear train 31. ing.

In addition, since the main body is configured in a Wanilo type, the last gear of the gear train 31 also takes an arcuate locus when the main body upper unit 27 is opened. Therefore, the rack 30 that meshes with this gear is also formed not on a straight line but on a circular arc.

Although the present embodiment is configured as described above, under normal conditions, the shutter 28 is located above the heat-resistant sheet 14 as shown in FIG. There isn't. By the way, when a problem such as a jam occurs and the main body upper unit 27 is opened around the hinge 26, the gears of the gear train meshing with the rack 30 rotate, and the gear 31a also rotates. Then, the arms 32 and 32 rotate integrally with this gear, the shutter 28 attached to the tip of this arm also rotates, and the heat-resistant sheet 14 rotates.
It comes to cover the bottom surface of. When the upper unit 27 is opened further upwards, the gear train 31 is freed from the rack 30, or is then rotated further to the stop position by a coil spring (not shown). That is, the shutter 28 covers the entire lower surface of the heat-resistant sheet 14.

This state is shown in FIG.

Next, when the main body upper unit 27 is closed, the gear train 31
or rack 3o. Then gear 3
1a rotates, and the arm 32 and the shutter 28 attached to the arm rotate against the coil spring. This situation is shown in FIG. Finally, as shown in FIG. 1, the pressurizing port 17 comes into pressure contact with the heating element 18, forming a nip and becoming a position where a fixing operation can be performed.

As described above, according to this embodiment, since the main body of the device is of the varnish type, when the upper unit of the main body is opened, the heat-resistant sheet is exposed and there is a risk of damage. When you open it, the shutter covers the heat-resistant sheet, so there is no danger like the one mentioned above.

Next, a second embodiment of the present invention will be described with reference to FIGS. 5 to 8.

The outline of the main body of the apparatus will be explained based on FIGS. 5 and 6. The main body upper unit 48 (FIG. 6), which includes the photosensitive tram 4, the developing device 6, the illumination lamp 3, etc., is opened and closed around the hinge part 47. It is now possible to do so. Furthermore, in the first embodiment, the fixing pressure roller 17 is pressurized and released in conjunction with the opening and closing of the main body upper unit, but in this embodiment, the fixing pressure roller 17 is manually operated separately from the opening and closing of the main body upper unit 48. It has a pressure release mechanism (described later), and the overall structure and operation are the same except that the rotation center position of the main body upper unit 48 is different, so a description thereof will be omitted.

In this way, the main body upper unit 48 can be opened and closed,
If a jam occurs in a location other than the paper feed section or fuser, open the upper unit 48 of the main body upward by removing the engaging part (not shown) (Fig. 6), and insert your hand into the main body to remove the jam. Paper can be removed. In the case of a jam in the paper feeding section, the feeding roller 7 is released upward by a pressure release mechanism (not shown) and the recording material 22 is removed from the sheet bundle P side.

Next, an embodiment of the fixing section will be described in detail with reference to FIGS. 7 and 8. FIG. 7 is a diagram showing a state in operation.

40 is a lever that can be rotated around a hinge portion 46; 38 is a heat-resistant sheet protective shutter a that is fixed to a gear 41 coaxial with the lever 40; and 39 is fixed to a gear 42 that meshes with the gear 41 and is rotatable. This is the heat-resistant sheet protective shutter b. An eccentric cam 44 is fixed to a rotatable gear 43 that meshes with the gear 42, and is located at a position where it can bias the bearing 45 supporting the pressure roller 17 from above to below.

In the state shown in FIG. 7, the pressure roller 17 is biased upward by the biasing means (not shown) in which the edge bearings 45 at both ends in the longitudinal direction are biased upward, and the heating body 18 is pushed through the heat-resistant sheet 14.
It is brought into pressure contact with the substrate to form a nip portion, so that fixing can be performed in the same manner as in the first embodiment.

In the present embodiment, which is configured as described above, when a jam occurs and the display flashes to indicate this, the user rotates the lever 40 in the direction shown by the arrow in FIG. . Then, the gear 41 rotates, and the heat-resistant sheet protection shutter a38 that is integrated with the gear 41 comes to cover half of the heat-resistant sheet 14, and the gear 41 that meshes with the gear 41
Since shutter 2 also rotates, shutter b also rotates and comes to cover half of shutter b. The eccentric cam 44 is also rotated in the direction of the arrow. As a result, the shutters 38 and 39 are
The heat-resistant sheet 14 is lowered into the space between the heat-resistant sheet 14 and the recording material 22, and covers almost the entire surface of the heat-resistant sheet 14. In addition, the eccentric cam 44 pushes the slide bearing 45 downward, the pressure roller 17 separates from the heating element 18, and the recording material 22 is easily pulled out in the L direction or the M direction with a slight force.

Note that the lever 40 is stopped by a stopper (not shown) at the position shown in Fig. 8 and cannot be rotated any further, so the shutters a38 and b39 also do not descend below the position shown in the figure, so the recording material cannot be moved. There is no interference on 22 at all. In this way, the pressure roller 17 is separated from the heating body 18, and the shutter a38. shutter b
39 is lowered, the user can safely and easily pull out the jammed recording material 22 without any fear of touching the heat-resistant sheet 14. Note that when cutting out the bow in the direction indicated by M in FIG. 8, the main body upper unit 4B must be opened as shown in FIG. 6.

After clearing the jam, by releasing the lever 40,
By means of a torsion coil spring (not shown) or the like, the fixing operation can be performed again by returning to the state shown in FIG. 12.

In this embodiment as well, the shutter 3839 closes the heat-resistant sheet 14 only when handling a jam, that is, when the pressure of the pressure roller 17 is released.
During normal operation, it escapes below the upper stay 35, so it does not obstruct the conveyance path of the recording material 22.
In addition, it is a very effective means because it eliminates the need to block the space for efficiently dissipating heat to the outside by the heating element 18.

Although not shown, the invention can be implemented in various ways. For example, instead of manually operating the lever 40 shown in FIGS. 7 and 8, it may be operated by a motor, and the motor may be activated by a jam occurrence signal or the like. In addition, instead of a jam signal, an activation signal from the apparatus main body is used to move a heat-resistant sheet protection member such as a shutter to a non-operating position away from the recording material conveyance path while the image forming apparatus is operating, and to move the recording material outside the main body. It is also possible to move the sheet protection member to a position where it covers the heat-resistant sheet after the ejection operation is completed. This makes it difficult for external foreign matter such as dust and dirt to adhere to the surface of the heat-resistant sheet, and also provides the effect that the image after fixing is less likely to deteriorate.

Furthermore, an opening r'A screen is provided on the side wall or casing of the conveying means located between the image forming means and the image fixing means, and the jammed recording material is removed from this opening and closing door. The heat-resistant sheet protective shutter can also be moved to an operating position and a non-operating position in conjunction with the opening/closing operation. In this way, even the occurrence of a jam on the upstream side of the fixing nip can be dealt with without damaging the heat-resistant sheet.

[Effects of the Invention] As detailed above, the present invention includes a protective member for protecting the heat-resistant sheet, and this protective member is movable between an operating position for protecting the heat-resistant sheet and an operating position for not protecting the heat-resistant sheet. Therefore, jam clearing work, maintenance, inspection, etc. can be performed without moving the protective member to the operating position and damaging the heat-resistant sheet, and without receiving burns from the heat-resistant sheet.

Furthermore, according to the invention, the protective member is moved to a non-operating position during image formation or fixing processing, and then to an operating position after the processing is completed, in addition to the above effects, there is no need to worry about the fixing unit being contaminated by dust during rest. .

According to the present invention, a protective member is provided and the heat-resistant sheet is protected by this protective member when necessary, so that the entrance for carrying in and out of the recording material can be made sufficiently large. Therefore, according to the present invention, jams do not occur near the conveyance path.

Furthermore, since the heat is radiated from the entrance, it is possible to suppress the rise in temperature of the entire fixing device due to the heating body.

[Brief explanation of drawings]

1 to 8 show an embodiment of the present invention, and FIGS. 9 to 13 show a conventional example, and FIG. 1 is a schematic cross-sectional view showing the entire embodiment of the present invention; Figures 2, 3, and 4 are diagrams showing the first embodiment of the fixing section, with Figure 2 showing the shutter in the non-operating position, and Figure 3 showing the shutter in the operating position, respectively. 4 is a plan view of FIG. 2, FIGS. 5 to 8 show the second embodiment, FIG. 5 is a schematic sectional view showing the entire embodiment, and FIG. 6 is a main body. 7 and 8 are cross-sectional views of the fixing section showing the shutter in the non-operating position and the operating position, respectively. FIG. 9 shows the entire conventional device 9. FIG. 10 is a cross-sectional view of the fixing unit, FIG. 11 is a cross-sectional view for explaining what to do when recording material gets stuck in the fixing unit, and FIG. 12 is a cross-sectional view of another conventional example. 13 are cross-sectional views showing the state in which the upper unit is opened. A... Image forming section B... Image fixing section 14...
・Heat-resistant sheet 17...Pressure roller 22...Recording material 28 38.39...Shutter and 4 other people

Claims (1)

[Scope of Claims] 1. An image forming means for forming a toner image on a recording material such as a transfer paper, and heating the unfixed toner image formed on the recording material by the image forming means through a heat-resistant sheet. a fixing means for fixing the unfixed toner image onto the recording material by heating and melting it with a body; the fixing means further includes a protective member for protecting the heat-resistant sheet; An image forming apparatus comprising: a protection operating position for protecting the image forming apparatus; and a protection member operating means for moving the protection member to a non-protection operating position. 2. An image forming apparatus according to claim 1, wherein the fixing means includes a protection member moving means that automatically moves the protection member to a protection operation position when a jam of the recording material is detected. 3. The fixing means according to claim 1 further includes a pressing means for pressing the recording material against the heating body, and a means for separating the pressing means and the heating means, and the fixing means is interlocked with the operation of the separating means. In the image forming apparatus, the protection member is moved to a protection operation position. 4. The fixing means according to claim 1 moves the protection member to the protection operation position after the recording material undergoes processing such as image transfer and fixation within the main body and is discharged from the main body, and moves the protection member to the protection operation position. The image forming apparatus further includes a protection member operating device that moves the protection member to a non-protection operation position immediately before operation starts. 5. An image forming means for forming a toner image on a recording material such as a transfer paper, and heating and melting the unfixed toner image formed on the recording material by the image forming means with a heating body through a heat-resistant sheet. a fixing means for fixing the unfixed toner image onto a recording material by means of a fixing means; and a conveying means for conveying the recording paper on which the unfixed toner image is formed from the image forming means to the fixing means, the fixing means further comprising a protective member for protecting the heat-resistant sheet, the protective member moving to a protective operation position in conjunction with the opening operation of an opening/closing door provided in a part of the casing where the conveying means is located;
An image forming apparatus characterized by comprising operating means for moving each to a non-operating position in conjunction with a closing operation.