JPH02302779A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the damage and deterioration of a fixing film and simultaneously the permanent deformation of a pressing member by switching the pressing member of a fixing device from a pressing status to a pressing releasing status with a switching means. CONSTITUTION:When an image forming device 100 is normally used and set, a paper ejecting tray 101 is as shown by a full line. When the normal use is changed, eg., the use of the device 100 is completed and moved, the paper ejecting tray is folded at a position shown by an alternate long and two dashes line. At this time, a lever 60 is pushed by a projection on the paper ejecting tray 101, and moreover, a lever 48 is pushed whereby the pressing member 27 is released. Thus, the damage of the fixing film 24 can be prevented, simultaneously the permanent deformation of the pressing member 27 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an image forming apparatus, and more specifically, an image forming means for forming a visible image on a recording material, and a heating element facing a fixedly supported heating element. The present invention relates to an image forming apparatus having a fixing device that heats and fixes the developed image by a pressure member that brings the recording material into close contact with the heating body through a fixing film.

[Prior Art] Conventionally, a belt fixing system as described in US Pat. No. 3,578,797 is known as a fixing device for an image forming apparatus. However, this type of belt fixing system has problems that need improvement, such as a long time required to raise the temperature to a predetermined temperature and a relatively large amount of electric power required.

Therefore, the present applicant has proposed a fixing device using a thin belt.

An image forming apparatus using the above fixing device has a configuration as shown in FIG.

In FIG. 6, reference numeral 1 denotes a document mounting table made of a transparent member such as glass, which scans the document by reciprocating in the direction of arrow a.

A short-focus, small-diameter imaging element array 2 is disposed directly below the document platform 1. The document image placed on the document platform 1 is illuminated by an illumination lamp 3, and the reflected light image is reflected by the array 2. Slit exposure is performed on the photosensitive drum 4. Note that this photosensitive drum 4 rotates in the direction of the arrow. Also 5
is a charger that uniformly charges the photosensitive drum 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 array 2, and an electrostatic image is formed thereon. This electrostatic image (electrostatic latent 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-like recording material P stored in the cassette S is rotated by a pair of conveying rollers that are pressed against each other in the vertical direction and rotated in synchronization with the image on the feeding roller 7 and the photosensitive drum 4. 8 onto the photosensitive drum 4. The toner image formed on the photosensitive drum 4 by the transfer discharger 9 is
The image is transferred onto the recording material P. Thereafter, the recording material P separated from the photosensitive drum 4 by a known separation means is guided to a fixing device 11 by a conveyance guide 10, subjected to heat treatment, 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.

FIG. 7 shows the fixing device 11. As shown in FIG.

In FIG. 7, reference numeral 20 denotes a low heat capacity linear heating body 1 fixedly supported on the device, and has a thickness of, for example, 1.0 mm.
A resistance material 22 is coated on an alumina substrate 21 having a width of 10 mm and a longitudinal length of 240+ nm to a width of 1.0 mm, and electricity is applied from both ends in the longitudinal direction. Current is DC 100V cycle 2
A pulse with a pulse-like waveform of 0 m5ec is given by varying the pulse width in accordance with the desired temperature and energy release amount controlled by the temperature measuring element 23. The habo pulse width is 0.5 to 5 m5ec.

In this way, the fixing film 24 moves in the direction of the arrow in the figure while coming into contact with the heating body 20 whose temperature and energy are controlled. As an example of this fixing film 24,
Heat-resistant film with a thickness of 20μ, such as polyimide,
It is an endless film made of polyetherimide, PεS, PF8, coated with 10μ of a release layer made of a fluororesin such as PTFE and P to F with a conductive layer added on at least the image contact side. Generally, the total gioooμ, more preferably less than 40μ.

The film is driven by the drive and tension of the drive roller 25 and the driven roller 26 to move the film in the direction of the arrow without wrinkles.

27 is a pressure roller having a rubber elastic layer with good moldability such as silicone rubber, which presses the low heat capacity linear heating body 20 through the fixing film 24 with a total pressure of 4 to 7 kg, and rotates in pressure contact with the fixing film 24. do.

Note that 28 is a recording material, 29 is a toner, and 30 is an entrance guide.

[Problems to be Solved by the Invention] However, in the fixing device shown in FIG. 7, since a heat-resistant thin endless film is used as the fixing film, there are problems as described below.

That is, the part where the toner image on the recording material is heated and fixed,
In other words, in the nip portion, due to fixing and offset problems, it is necessary to press the film against the fixedly supported low heat capacity linear heating body 20 with a certain amount of force or more. However, if the device is left under pressure even when not in use, the fixing film 24 may become wrinkled or streaked, or in the case of a coated film, the coating may be damaged, or the pressure applied by the pressure member may There is a problem that the pressure roller 27 may be deformed. As a result, image quality has deteriorated. Furthermore, if the pressure is released during jam processing and then an attempt is made to fix the image, the temperature of the fixing film 24 will rise abnormally, resulting in deterioration of the fixing film 24.

The present invention aims to solve the above problems. That is, an object of the present invention is to provide an image forming apparatus having a fixing device that can prevent damage to the fixing film and prevent permanent deformation of the pressure member.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an image forming means for forming a visible image on a recording material, and an image forming means for forming a visible image on a recording material, and an image forming means for forming a visible image on a recording material, and an image forming means for forming a visible image on a recording material, and an image forming means for forming a visible image on a recording material, and an image forming means for forming a visible image on a recording material. In the image forming apparatus, the image forming apparatus includes a fixing device that heats and fixes the visible image by a pressure member that brings the recording material into close contact with the heating body, wherein the pressure member of the fixing device is in a pressurized state and a pressure release state. and when the state of at least a portion of the apparatus main body including the fixing device is changed from the normal installation and use state, the pressurized state is switched to the pressurized release state. The system is equipped with a switching means for switching.

[Function] According to the present invention, when the state of at least a portion of the apparatus body including the fixing device is changed from the normal installed and used state, the switching means releases the pressure member from the pressurized state. Since the fixing film is switched to the above state, damage to the fixing film can be prevented, and at the same time, permanent deformation of the pressure member can be prevented.

[Embodiment] FIG. 1 shows a first embodiment of the present invention, and FIG. 2 shows an enlarged view of the fixing device shown in FIG. 1.

In FIG. 1, when the image forming apparatus +00 is normally installed and used, the paper discharge tray 101 is in an open state as shown by a solid line. Here, if you want to change the normal usage status, for example, when you finish using the device and
00, the paper discharge tray 101 is folded to the position shown by the two-dot chain line in FIG. At that time, paper output tray 10
The protrusion on the pressure roller 27 presses the lever 60, which in turn presses the lever 48, and the pressure roller 27 is released from the pressurized state.

The mechanism for releasing the pressure of the pressure roller 27 and returning to the pressurized state when the image forming apparatus 1 (IQ) is installed and used will be explained with reference to FIG.

In FIG. 2, the pressure roller 27 is attached to the pressure lever 64 via a bearing 69. Although FIG. 2 shows the members attached to the front side, similar members are also attached to the rear side.

The pressure lever 64 is rotatably attached around a fulcrum shaft 68. On the other hand, the lever 45 at the top of the fixing device is held rotatably about a fulcrum shaft 46, and the pressure lever 64 and lever 45 are connected by a spring 66.

In the state shown in FIG. 2, the lever 48 and the bottle 4 on the lever 45 are
7 is engaged, the pressure lever 6 is pressed by the spring 66.
A predetermined pressure is applied through 4.

Now, as mentioned above, when the paper output tray 101 is folded and closed, the left end of the lever 60 is pushed, so the bin 62 on the lever 60 and the upper end of the lever 48 engage, and the lever 48 is It rotates in the direction of arrow E around the support shaft 49. At this time, the engagement between the bin 47 and the lever 48 is released, and the lever 45 rotates in the direction of arrow F.

Therefore, the pressure lever 64 connected by the spring 66 also rotates in the direction of arrow G, and as a result, the pressure roller 27 is released from pressure.

Note that a stopper 67 is provided to prevent over-rotation of the lever 45 at this time.

Next, when the pressure is restored during use, when the copy start button is pressed, the solenoid 65 enters the suction state and the connector 63
, and push lever 45 in the direction of arrow H. As a result, the lever 48 and the bottle 47 engage, and the pressure roller 27
becomes pressurized and the pressurized state is maintained.

As described above, when the image forming apparatus 100 is not in the normal installation and use state, that is, when the paper output tray 101 is folded and closed, the above mechanism applies pressure to the pressure roller 27 of the fixing device 11. The condition is canceled and the fixing film 2
4 and pressure roller 27 are protected.

FIG. 3 shows a second embodiment of the invention.

In FIG. 3, the image forming apparatus 100 is in a normal installed and used state, the lever 102 is separated from the lever 48, and the pressure roller 102 is moved by a mechanism similar to that of the first embodiment.
7 is in a pressurized state. Consider a case where this normal installation and use condition is changed and the image forming apparatus 1oo is placed vertically with the legs 103 at the bottom. At this time, the left end of the lever 102 passing through the leg 103 is pushed by the installation surface, and the right end of the lever 102 pushes the lever 48. the result,
The pressure state of the pressure roller 27 is released by a mechanism similar to that described in the first embodiment.

In this way, by changing the image forming apparatus 100 from the normal installation and usage state to the vertical installation state, the pressure roller 27
The pressurized state can be released.

FIG. 4 shows a third embodiment of the invention.

In FIG. 4, when the image forming apparatus 100 is normally installed and used, the handle 107 is retracted vertically downward. Here, the image forming apparatus 100 is changed from the normal installation and usage state.
When moving the handle 107, raise the handle 107. At this time,
As the wire lobe 108 is pulled, the lever 48 is pulled and disengaged from the lever 45. As a result, the pressure roller 2
The pressurized state of 7 is released.

FIG. 5 shows a fourth embodiment of the invention.

In FIG. 5, when the power switch 110 is pressed, the h-shaped lever is moved to pressurize the pressure roller 27 and at the same time turn on the microswitch 111. At this time, this state is maintained by a locking mechanism (not shown). Next, turn off the power switch 110 and turn the lever 109
rotates in the direction of arrow J, and the pressurized state of the pressure roller 27 is released, and at the same time, the microswitch 111 is also turned off.

Each embodiment of the present invention has been shown above, but other embodiments include those in which the present invention is applied to image forming apparatuses such as laser beam printers and LED printers.
It is also effective in a stationary image forming apparatus. Further, in the above-described embodiment, the paper ejection tray 101 and the handle 107 are used as examples of parts of the apparatus main body that change the pressure state of the pressure roller 27 of the fixing device. The present invention can be applied to any member that can be moved manually. Furthermore, although the pressure roller 27 has been described in each of the above embodiments, the present invention can be applied to any pressure member. For example, the same applies to a belt-shaped pressure member applied to one or more rollers.

[Effects of the Invention] As explained above, according to the present invention, when the state of at least a portion of the main body of the apparatus including the fixing device is changed from the normally installed state, the switching means changes the pressure of the fixing device. Since the member is switched from a pressurized state to a pressurized state,
Damage and deterioration of the fixing film can be prevented, and permanent deformation of a pressure member such as a pressure roller can be prevented. Moreover, in addition to this, it can also be used to release pressure when handling a jam, and there is no need to provide a separate pressure release means for handling a jam.Furthermore, according to the present invention, the recording material When passing through the fixing device,
Since the pressure member is always in the pressurized state, the fixing film will not be heated with electricity in the released state, and therefore there is no risk of damage or deterioration of the fixing film.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional side view showing the first embodiment of the present invention;
The figure is an enlarged side view of the fixing device shown in Fig. 1, Fig. 3 is a sectional side view showing a second embodiment of the present invention, and Fig. 4 is a sectional side view showing the third embodiment. , FIG. 5 is a cross-sectional side view showing the fourth embodiment, FIG. 6 is a cross-sectional side view for explaining an image forming apparatus having a fixing device using a thin belt, and FIG. 7 is a cross-sectional side view showing the fourth embodiment. FIG. 3 is an enlarged side view of the fixing device shown in FIG. DESCRIPTION OF SYMBOLS 11... Fixing device, 20... Low heat capacity linear heating body, 24... Fixing film, 25... Drive roller, 26
...Followed roller, 27...Pressure roller, 45.
... Lever, 48 ... Lever, 64 ... Pressure lever, 66 ... Spring, 100 ... Image forming device, 101 ... Paper ejection tray, 103 ... Leg,
107...Handle. 4 others Figure 7

Claims (1)

[Scope of Claims] 1. An image forming means for forming a visible image on a recording material, and a pressure member that presses against a fixedly supported heating body and brings the recording material into close contact with the heating body through a fixing film. In the image forming apparatus having a fixing device that heats and fixes the visible image, the pressure member of the fixing device is provided so as to be able to take a pressurized state and a pressurized state, and
An image characterized by comprising a switching means for switching from the pressurized state to the pressurized state when the state of at least a portion of the apparatus main body including the fixing device is changed from a normal installation and use state. Forming device. 2. The apparatus according to claim 1, wherein the switching means switches the pressure member from the pressurized state to the pressurized state when the apparatus main body including the fixing device is placed in an upright position with its side facing down. Image forming device. 3. The switching means constitutes a part of the apparatus main body including the fixing device, and there are two states: a gripping state, which is a state in which the apparatus main body is set when carrying it, and a retracted state, which is a state in which the apparatus main body is evacuated for installation. 2. The image forming apparatus according to claim 1, wherein the switching means switches the pressure member from the pressurized state to the pressurized state when the handle is set to the gripping state. 4. The switching means constitutes a part of the apparatus main body including the fixing device, and the apparatus main body is in a guiding state in a predetermined position when it is installed and used, and in a state in which it is evacuated from this guiding state. 2. The switching means is configured to switch the pressure member from the pressurized state to the pressurized state when the recording material guiding tray that is in a certain retracted state is set in the retracted state. The image forming apparatus described above.