JP7487585B2 - Fixing device and image forming apparatus - Google Patents

Description

The present invention relates to a fixing device and an image forming device.

Electrophotographic image forming devices are equipped with a fixing device for fixing a toner image onto a recording medium such as transfer paper. In the fixing device, for example, a nip is formed by pressing a pressure member (pressure roller) against a heated fixing member (fixing roller or fixing belt), and the toner carried on the recording medium melts as the recording medium passes through the nip, fixing the toner image onto the recording medium.

The fixing device requires maintenance and replacement of parts not only when it breaks down but also depending on the usage conditions. For example, when a paper jam occurs because the paper gets stuck in the gap of the transport path or gets wrapped around the fixing member, maintenance is required to remove the paper.
Such work affects the burden on users and service personnel and labor costs, leading to increased costs, so various techniques have been proposed to make the work easier (see, for example, Patent Documents 1 and 2).

Patent document 1 discloses a configuration for an image forming device that improves the positioning accuracy of a pull-out type fixing unit and improves the ease of handling jams near the fixing unit. The configuration discloses a configuration in which the fixing unit is urged toward the image forming unit by a spring member, and when the pull-out member is slid to the storage position and locked into the device main body, the fixing unit is directly positioned by being stopped against the second paper transport path or the image forming unit against the force of the spring member.
Patent document 2 discloses a fixing device that is easy to maintain and to remove jammed paper, in which a bracket member having multiple separation claws rotates around a fulcrum center in a direction to move the separation claws away from the fixing belt.

In a configuration in which the fixing device (fixing unit) can be opened and closed separately when clearing a jam, for example, if a separation mechanism with a separation claw opens and closes vertically, the separation mechanism may inadvertently drop (move in the closing direction) during the opening and closing operation. Because the separation mechanism is provided with a separation claw with a sharp tip, there is a risk that the falling of the separation mechanism may damage the surface of the fixing member or the operator's fingers.
Patent document 2 discloses a technology for preventing the separation claws from being pressed against the surface of the fixing belt with impact by separating the separation claws, but does not disclose a technology for preventing the bracket member equipped with the separation claws from falling.

The present invention aims to provide a fixing device that can prevent an opening/closing body that can swing open and close between a closed position that covers the inside of the device and an open position that opens it from accidentally falling in the closing direction.

In order to solve the above problem, the fixing device of the present invention comprises at least an apparatus base and an opening/closing body attached to the apparatus base so as to be able to swing and rotate, and one of the apparatus base and the opening/closing body has a curved member having a plurality of grooves formed on a curved surface along the rotation direction of the opening/closing body, and the other has an engaging member that engages with the grooves of the curved member, and the apparatus base and the opening/closing body are fixed by the engaging member engaging with the curved member, and the opening/closing body can be fixed to the apparatus base at a plurality of positions corresponding to the plurality of grooves between a closed position that covers the inside of the apparatus and an open position that opens it, and the curved member has a non-engaging portion that does not engage with the engaging member, and when the opening/closing body is in the closed position, the engaging member is located in the non-engaging portion of the curved member .

The present invention provides a fixing device that can prevent an opening/closing body that can swing open and close between a closed position that covers the inside of the device and an open position that opens it from accidentally falling in the closing direction.

1 is a schematic diagram illustrating an example of an image forming apparatus according to the present invention. FIG. 2 is a perspective view illustrating a state in which a fixing device mounted on the image forming apparatus is pulled out. 1 is a schematic perspective view of an external appearance of a fixing device according to the present invention; 1 is a schematic perspective view of an external appearance of a fixing device according to the present invention; 5 is a partial enlarged view showing an example of a fitting member and a curved member of the fixing device according to the present invention. FIG. 5A to 5C are explanatory diagrams illustrating the opening and closing of a separation unit of the fixing device according to the present invention. 5A to 5C are explanatory diagrams illustrating the opening and closing of a separation unit of the fixing device according to the present invention. 5 is an explanatory diagram of a mechanism for restricting the insertion of the fixing device.

The fixing device and image forming device according to the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the embodiments shown below, and can be modified within the scope of what a person skilled in the art can imagine, including other embodiments, additions, modifications, deletions, etc., and any aspect is within the scope of the present invention as long as it achieves the functions and effects of the present invention.

An embodiment of an image forming apparatus according to the present invention will be described with reference to FIG.
1 is a schematic diagram showing the configuration of an image forming apparatus, specifically a copying machine capable of forming monochrome images, which can also function as a printer when connected to a PC.

The image forming apparatus of this embodiment is a copier, and therefore has a document reading unit that functions as a scanner, but if the device is a machine dedicated to online PC output, such as a so-called printer version, and has a built-in controller, the document reading unit may be omitted.

The schematic configuration and operation of the image forming apparatus of this embodiment will be described below.
The image forming apparatus 10 has a scanner unit 104 that houses an illumination device, an optical system, a CCD image sensor, and the like.
Above the scanner is provided an automatic document reader (hereinafter referred to as an "ADF unit" (ADF: Auto Document Feeder)) 103. The ADF unit 103 automatically transports a document and sends the document to the reading surface of the contact glass.

The operator places an original on the contact glass above the scanner unit 104 or on the ADF unit 103, selects a mode using the function selection keys on the operation panel 101, and sets the desired image formation conditions by operating the numeric keypad, function keys, etc. while checking the contents displayed on the LCD screen. The image forming device is equipped with a call light 100 that indicates the operating status to the operator.

The image signal read by the scanner unit 104 is A/D (Analog/Digital) converted by the SBU (Sensor Board Unit) and then irradiated as laser light from the laser writing unit 112. The laser light is focused by a cylindrical lens of the laser writing unit 112 and line-scanned in the main scanning direction by a polygon mirror, forming an electrostatic latent image on the photosensitive drum 116.

The developing unit 113 includes a cleaning unit 114 and a charger around the photosensitive drum 116. A charger 115 is used to charge the surface of the photosensitive drum 116.
A high voltage is applied to the charger 115 from a power supply unit (PSU) via a receptacle, electrode terminals, conductive bearings, and the like.

The toner supplied from the toner supply unit (toner bottle) 111 and the developer that has been filled in advance in the development unit 113 are stirred and mixed by the internal transport screw and transported to the development roller. The toner is electrostatically attracted by magnetic force and is negatively charged.

The two-component developer carried by the developing roller is regulated to an appropriate amount by a developer brush regulation member such as a doctor blade or casing arranged below the developing roller, and then the frictionally charged toner in the two components moves onto the photoconductor drum 116 due to the bias voltage and selectively adheres to the electrostatic latent image.

The toner concentration inside the developing unit 113 is detected from the charge amount by a toner concentration sensor disposed at the bottom surface.
Any untransferred toner remaining on the photoconductor drum 116 after transfer is scraped off by a cleaning blade provided in the cleaning unit 114 and transported to a waste toner bottle 125 for collection.

In addition, an inlet seal made of mylar or a sponge-like material is appropriately provided around the development unit 113 to prevent toner from scattering.

The visible image formed by the toner on the photosensitive drum 116 is first transferred onto the intermediate transfer belt unit 105.

When the transfer paper is transported by the paper transport section 117 and passes through the registration roller section, the toner on the intermediate transfer belt unit 105 is transferred to the transfer paper by the positive charge from the secondary transfer roller as it passes between the nip between the intermediate transfer belt unit 105 and the secondary transfer unit 118.

After transfer, any untransferred toner remaining on the intermediate transfer belt unit 105 is scraped off by a cleaning blade in the belt cleaning unit 106 and transported to and collected in the waste toner bottle 125.

A high voltage is applied to the transfer roller from the PSU through a receptacle, electrode terminals, conductive bearings, and the like.
In order to suppress fluctuations due to the printing environment, the type of transfer paper, and the like, constant current control is performed, and the transfer current is appropriately switched according to the paper feed tray, the size and thickness of the transfer paper, and the like.

In addition, to prevent the back of the transfer paper from being soiled by toner adhering to the transfer roller, a negative bias can be applied to the transfer roller at a specified timing to return the adhering toner to the intermediate transfer belt unit 105. This cleans the transfer roller.

The transfer paper onto which the toner has been transferred is transported to a fixing device (fixing unit) 11, where a certain temperature and pressure are applied to heat-fuse the toner image onto the paper.
The fixing roller in the fixing device 11 is provided with a thermistor to detect the surface temperature and control the ON/OFF of the heater. The thermistor may be of a contact type or a non-contact type. A temperature fuse is also provided to prevent the temperature from rising too high.

The fixing device 11 of this embodiment includes at least a fixing member, a heating unit, and a pressure member.
The fixing members include, for example, a heating roller 49 , a fixing roller 48 , and a fixing belt 47 stretched between the heating roller 49 and the fixing roller 48 .
The pressure member (pressure roller) 43 is, for example, a hollow member that rotates in contact with the fixing member, and forms a nip portion between the fixing belt 47 and the pressure member. The pressure and depressurization of the nip portion are controlled by a cam. The pressure member 43 may be provided with a heating member inside.
Other configurations of the fixing device 11 will be described later.

The transfer paper with the toner image heat-fused thereto is separated from the heating roller and fixing belt by a fixing separation plate, and then passes through a reversing and discharging unit 109, or is printed on both sides according to set conditions, and is then discharged onto a paper discharge tray 126. If a post-processing device or the like is connected, the transfer paper is conveyed to the transfer paper inlet of the connected device.
The image forming apparatus also includes casters 127 for moving the main body.

The image forming device 10 of this embodiment forms images using the electrophotographic method through the above-mentioned configuration and operation.

Next, the configuration of the fixing device 11 according to the present invention will be described with reference to FIGS.
As shown in FIG. 2 , the fixing device 11 of this embodiment is placed on a slide rail 12 inside the image forming apparatus 10 and is mounted so as to be able to be pulled out to the outside of the image forming apparatus 10 .
After the image forming apparatus 10 is stopped and the fixing device 11 is cooled sufficiently, the fixing device 11 mounted on the slide rails 12 is pulled out. Then, the fixing device 11 removed from the slide rails 12 is placed on a work space, and the maintenance work is started.
After the maintenance work is completed, the fixing device 11 is placed on the slide rails 12 and stored in the image forming apparatus 10 .

The fixing device 11 of this embodiment has multiple components, such as a heating unit having a fixing member and a heating means, a pressure unit having a pressure member that contacts the fixing member to form a nip portion, and a separation unit having a separation member (e.g., a separation claw) that separates the paper after the toner image is fixed.
Hereinafter, the separation unit may be referred to as an "opening/closing body", and the main body portion consisting of the heating unit and the pressurizing unit to which the separation unit is attached may be referred to as an "apparatus base".

3 and 4 are perspective views of the fixing device 11 removed from the slide rail 12. FIG.
FIG. 3 shows the separation unit 13 in a completely open state, and FIG. 4 shows the separation unit 13 in a fixed state between an open position and a closed position.

In conventional fixing devices, a coil spring or the like is generally provided as an opening/closing auxiliary member 25 to prevent the openable/closable separation unit (opening/closing body) 13 from falling under its own weight, and the tension of the coil spring maintains the weight balance when opening and closing. However, if the tension of the coil spring is insufficient, the holding force is also insufficient, and the separation unit 13 may fall under its own weight. The careless dropping of the separation unit 13 reduces work efficiency and may cause damage to the fixing member or injury to the user's fingers due to the separation claw 21 having a sharp tip. Similarly, if the tension of the coil spring is excessive, it may be difficult to perform a smooth opening and closing operation, which may lead to a decrease in work efficiency.
In contrast, the fixing device according to the present invention can fix the separation unit 13 at a desired position between the open position and the closed position as shown in FIG. 3, thereby preventing the separation unit 13 from accidentally falling or moving.

The fixing device of the present invention at least comprises an apparatus base 14 accounting for more than half of the total weight, and an opening/closing body 13 attached to the apparatus base 14 so as to be able to swing and rotate, and one of the apparatus base 14 and the opening/closing body 13 has a curved member 30 having a plurality of grooves 31 formed on a curved surface along the rotation direction of the opening/closing body 13, and the other has an engaging member 22 that engages with the grooves 31 of the curved member 30, and the apparatus base 14 and the opening/closing body 13 are fixed to each other by engaging the engaging member 22 with the curved member 30, and the opening/closing body 13 can be fixed to the apparatus base 14 at a plurality of positions corresponding to the plurality of grooves 31 between a closed position that covers the inside of the apparatus and an open position that opens it.
In addition, it is sufficient that the curved member 30 has a curved surface at a portion where the surface connecting the tips of the ridges and valleys that make up the multiple grooves 31 is curved; it is not necessary for the entire curved member 30 to be formed of a curved surface.

In the fixing device 11 of this embodiment shown in FIGS. 3 and 4, the opening/closing body 13 is a separation unit that separates the recording medium (paper) 24 after the toner image is fixed.
In the fixing device 11 of this embodiment, the curved member 30 is provided on the device base 14 , and the fitting member 22 is provided on the opening/closing body 13 .

The engaging member 22 is slidable in the direction of the rotation axis of the opening/closing body 13 (separation unit) (the direction indicated by the arrow D in FIG. 4) between a position where it engages with the curved member 30 and a position where it does not engage with the curved member 30.

The engaging member 22 also has a biasing member 26 that biases the engaging member 22 in the direction of engaging with the curved member 30.

In the fixing device of this embodiment, the operation of swinging and rotating the opening/closing body (separation unit) 13 to open and close is performed by manually moving the fitting member 22 and the operation knob 23 .
First, while pressing the biasing member (coil spring) 26, slide the engaging member 22 to the right direction of arrow D with the left hand, while raising the operating knob 23 to position 23a with the right hand, thereby releasing the lock and allowing the opening/closing body (separation unit) 13 to be opened and closed.

By releasing the fitting member 22 that was slid and held, the fitting member 22 returns to the left direction of the arrow D due to the biasing force of the biasing member 26. As a result, the fitting member 22 fits into the groove portion 31 of the curved member 30, and the opening/closing body (separation unit) 13 is fixed in the position at the time of fitting.
The fixed position of the opening/closing body (separation unit) 13 also changes depending on the position at which the fitting member 22 fits into the groove portion 31 of the curved member 30. That is, the opening/closing body (separation unit) 13 is swung and rotated to fit the fitting member 22 into the groove portion 31 of the curved member 30 at a desired position corresponding to the groove portion 31, thereby allowing the opening/closing body (separation unit) 13 to be fixed to the device base 14 in multiple stages.

In addition, the present invention is not limited to the above-described manner in which the engaging member 22 is slidably moved relative to the curved member 30, but the curved member 30 can be slidably moved in the direction of the rotation axis of the opening/closing body 13 (the direction of the arrow D in the figure) between a position where it engages with the engaging member 22 as shown in FIG. 5(A) and a position where it does not engage with the engaging member 22 as shown in FIG. 5(B).

In this embodiment, the curved member 30 is provided with a biasing member 33 such as a compression spring that biases the curved member 30 in a direction in which the curved member 30 fits into the fitting member 22 .
5(B), the curved member 30 is slid to the right in the direction of the rotation axis of the opening/closing body 13 (arrow D in the figure), thereby disengaging it from the engaging member 22. By releasing the curved member 30 that was being held, the biasing force of the biasing member 33 causes it to return to the direction in which it engages with the engaging member 22 (leftward in the figure, indicated by arrow D) as shown in FIG.

6 and 7 are explanatory diagrams showing the open/closed state of the opening/closing body (separation unit) 13 and the positional relationship between the engaging member 22 and the curved member 30, with FIG. 6 being a front view in the transport direction of the recording medium, and FIG. 7 being a side view.
Figures 6(A) and 7(A) show the opening/closing body (separation unit) 13 fixed in the closed position, Figures 6(B) and 7(B) show the opening/closing body (separation unit) 13 fixed in the middle of the opening/closing operation, and Figures 6(C) and 7(C) show the opening/closing body (separation unit) 13 in a completely open position.

FIG. 8 is a schematic diagram showing the fitting member 22 and the curved member 30 according to the state of the opening/closing body (separation unit) 13, and shows the following states.
In FIG. 8A, the opening/closing body (separation unit) 13 is in the closed position, and the fitting member 22 is biased by the biasing member 26 in the direction of fitting into the groove portion 31 of the curved member 30.
As shown in Figure 8 (A), the curved member 30 has a non-engaging portion 32 that does not engage with the engaging member, and when the opening/closing body (separation unit) 13 is in the closed position, the engaging member 22 is located in the non-engaging portion 32 of the curved member 30.

FIG. 8B shows a state in which the opening/closing body (separation unit) 13 is in the process of opening and closing.
8C shows a state in which the opening/closing body (separation unit) 13 is fixed in the middle of the opening/closing operation. The fitting member 22 is returned to the left in the figure by the biasing force of the biasing member 26, and is fixed by fitting into the groove portion 31 of the curved member 30.
8(D) shows a state in which the opening/closing body (separation unit) 13 is open. In FIG. 8(D), the fitting member 22 is located at the non-fitting portion 32 of the curved member 30.

The fixing device 11 of this embodiment is a fixing device mounted on the image forming apparatus 10 so as to be removable, as described above.
8E, the opening/closing body (separation unit) 13 is in the closed position as in FIG. 8A, and in this state, it does not interfere with the erroneous insertion restricting member 50 and is housed in the image forming apparatus 10. In FIG.
8(F) shows a state in which the opening/closing body (separation unit) 13 is fixed in the middle of the opening/closing operation, as in FIG. 8(C). In this manner, when the fitting member 22 is fitted into the groove portion 31 of the curved member 30, it interferes with the erroneous insertion prevention member 50 and is therefore not accommodated in the image forming apparatus 10.

The incorrect insertion prevention member 50 interferes when the engaging member 22 is in a position where it engages with the groove portion 31 of the curved member 30, and when it is in the non-engaging portion 32 of the curved member 30 where the opening/closing body (separation unit) 13 is in the open state as shown in Figure 8 (D).
Therefore, the fixing device 11 can be housed in the image forming device 10 only when the opening/closing body (separation unit) 13 is held in the closed position, thereby avoiding the occurrence of malfunctions such as accidentally damaging the opening/closing body (separation unit) 13.

As described above, the fixing device according to the present invention can prevent the opening/closing body (separation unit) that can swing open and close between a closed position that covers the inside of the device and an open position that opens it from accidentally falling in the closing direction, without reducing work efficiency, reducing the burden and labor costs on users and service personnel, and preventing damage to the fixing member and injuries to the user's fingers.

10 Image forming device 11 Fixing device 12 Slide rail 13 Opening/closing body (separation unit)
REFERENCE SIGNS LIST 14: device base 21: separation claw 22: engagement member 23: operation knob 24: paper 25: biasing member 26: opening/closing auxiliary member 30: curved member 31: groove 43: pressure member 47: fixing belt 48: fixing roller 50: incorrect insertion prevention member

JP 2007-171850 A JP 2005-352383 A

Claims (9)

The device includes at least a device base and an opening/closing body that is pivotally and rotatably attached to the device base,
a curved member having a curved surface along a rotation direction of the opening/closing body, the curved surface being a curved member having a plurality of grooves formed thereon, the curved surface being aligned with the rotation direction of the opening/closing body, and a fitting member being fitted into the grooves of the curved member, the curved member being fitted into the other of the curved member,
The fitting member is fitted into the curved member, thereby fixing the device base and the opening/closing body,
the opening/closing body is fixable to the device base at a plurality of positions corresponding to the plurality of grooves between a closed position that covers the inside of the device and an open position that opens the inside of the device,
the curved member has a non-engagement portion that does not engage with the engagement member,
When the opening/closing body is in the closed position, the engaging member is located in the non-engaging portion of the curved member . The fixing device according to claim 1, characterized in that the engaging member is slidable in the direction of the rotation axis of the opening/closing body between a position where it engages with the curved member and a position where it does not engage with the curved member. The fixing device according to claim 1 or 2, characterized in that it has a biasing member that biases the fitting member in a direction in which it fits into the curved member. The fixing device according to claim 1, characterized in that the curved member is slidable in the direction of the rotation axis of the opening/closing body between a position where it engages with the engaging member and a position where it does not engage with the engaging member. The fixing device according to claim 1 or 2, characterized in that it has a biasing member that biases the curved member in a direction in which it fits into the fitting member. 6. The fixing device according to claim 1, wherein the curved member is provided on the device base, and the fitting member is provided on the opening/closing body. 7. The fixing device according to claim 1, wherein the opening and closing member is a separation unit having a separating member for separating the recording medium after the toner image is fixed thereto. A fixing device that is accommodated in an image forming apparatus and is mounted so as to be removable from the image forming apparatus,
8. The fixing device according to claim 1, wherein the fixing device is not accommodated in the image forming apparatus when the curved member is fitted with the fitting member. 9. An image forming apparatus comprising the fixing device according to claim 1 .

Images