JPH04161976A - Fusing device - Google Patents

Abstract

PURPOSE:To prevent a leak and a short circuit due to a lead wire by providing an insulating member coating and insulating a main body part of a thermal fuse together with the lead wire, and a fixing member nippedly holding the main body part from the upper side of the insulating member and fixing the main body part. CONSTITUTION:A thermal fuse 40 has a main body part 41 and a pair of metal- rodlike lead wires 42 connected to both the ends of the main body part 41. The main body part 41 of the thermal fuse 40 and the lead wires 42 are inserted in an insulating tube 43, and a round type terminal 44 is fixed to a tip part 42a of the lead wire 42. Then the insulating tube 43 is heated to be contracted, and the main body part 41 and the lead wire 42 are coated and insulated with the insulating tube 43 to assemble a thermal fuse assembly. The thermal fuse assembly is fixed to a frame 1 with a fuse fixing member 46, and concurrently the main body part 41 is provided near to a fixing roller 3. This insulates an exposed part of the lead wire, and also suitably retain an interval between the main body part 41 and the roller 3, to eliminate a leak and a short circuit due to the lead wire 42.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device installed in an image forming apparatus or the like, and more particularly, to a fixing device in which a temperature fuse is provided close to a fixing roller. .

[Prior Art] Conventional fixing devices of this type include those shown in FIGS. 5 to 7, for example. In addition, Fig. 5 is an exploded perspective view, and Fig. 6 is an exploded perspective view.
The figure is an exploded perspective view of the temperature fuse assembly 23, and FIG. 7 is a diagram showing the positional relationship between the temperature fuse assembly 23 and the fixing roller 3 described above. In FIG. 5, l is a frame, 2 is a guide plate for the fixing roller, 3 is a fixing roller, 4 is a bearing for the fixing roller, 5 is a pressure roller, 6 is a bearing for the pressure roller, and 7 is a spring for the pressure roller. , 8 is a paper ejection shaft, 9 is a paper ejection bearing, 10 is an E-shaped ring, 11 is a paper ejection plate blade, 12 is a paper ejection sensor shaft, 13 is a separation claw for the fixing roller, 14 is a separation claw 15 is a gear for the fixing roller, 16 is an idler for paper ejection, 17 is a spacer for the idler, 1 is a gear around the paper ejection shaft, 19 is a retaining ring for the fixing roller, 20 is a heater, 21.22 is a heater holder It is.

On the other hand, 23 is a temperature fuse assembly, and the temperature fuse assembly 23 has a fuse body 24 and a pair of leads connected to both ends of the fuse body 24, as shown in FIG. ! 25. Double-layered heat-shrinkable insulating tube 26, bifurcated leg portion 27a, and insertion hole 27
It is comprised of a pair of L-shaped brackets 27, each having a support portion 27c with a hole 27b.

Then, the fuse body 24 is fitted into the insulating tube 26, and the lead wire 24 is inserted into the insertion hole 27b of the bracket 27.
5 is inserted, and at the same time, the distal ends of the support portions 27c are respectively fitted into both ends of the insulating tube 26, and the above-mentioned members are assembled. Next, the insulating tube 26 is heated and contracts, and the fuse body 24 and the proximal end 25a of the lead wire 25 are covered with the insulating tube 26. At the same time, the insulating tube 26 grips the distal end of the support part 27c and closes the fuse body. 24 and lead wire 25 are supported by a bracket 27, and a temperature fuse assembly 23 as shown in FIG. 5 or 7 is assembled. In the temperature fuse assembly 23 assembled in this way, the legs 27a of the bracket 27 are fitted into the fixing holes 1a of the frame, and the hooks 27d formed on the legs 27a are inserted.
is fixed and positioned relative to the fixing roller 3.

As shown in FIG. 7, since it is necessary to make the surface temperature of the fuse body 24 approximately equal to the surface temperature of the fixing roller 3, the distance between the fuse body 24 and the fixing roller 3 is set as follows.
For example, the dimensions of the bracket 27 are set to about 3[lI] so that the fuse body 24 can be brought sufficiently close to the fixing roller 3. In addition, the insertion hole 27b of the bracket 27
A tip 25b of the lead wire 25 protrudes without being covered or insulated, and a temperature fuse terminal 28, 29 shown in FIG. 1 is connected to this tip 25b. Note that a thermistor 30 is provided near the temperature fuse assembly 23.

(Problem to be solved by the invention) However, in such a conventional fixing device,
When the temperature fuse assembly 23 is attached to the frame 1, the lead wire 25, especially the exposed tip portion 25b not covered by the insulating tube 26, and the fuser roller 3
The zero interval was only about 3 mm, similar to the fuse body 24, and it was close to the fixing roller 3. Therefore, if the heater 20 of the fixing roller 3 is damaged, the fixing roller 3 can
The potential is the same as 200V (in the case of a 200V device), and if the distance between the lead wire 25 and the fixing roller 3 is small, there is a problem that leaks or short circuits are likely to occur.

Therefore, according to safety standards, the lead wire 25 and the fixing roller 3
The lead wire 25 must be separated from the fixing roller 3 to 4.
If the fuse body 24 is separated from the fixing roller 3 by more than 4 mm, the fuse body 24 will also be separated from the fixing roller 3 by more than 4 mm.
There was a problem in that the surface temperature of the fixing roller 3 was different from that of the fixing roller 3. In addition, the tip 2 of the lead wire 25
5b is doubly insulated by the insulating tube 26, the above-mentioned bracket shape cannot be used, and a new fixing method is required, neither of which could satisfy safety standards.

Further, since the fuse body 24 and the lead wire 25 are supported and positioned by the bracket 27 by the lead wire 25 inserted through the insertion hole 27b and the insulating tube 26 with low rigidity, the position of the fuse body 24 is unstable. There was also a problem. Specifically, when installing the temperature fuse assembly 23, the fuse body 24 may be bent due to bending of the insulating tube 26 and lead wire 25.
In some cases, the distance between the fixing roller 3 and the fixing roller 3 changes.

(Object of the Invention) Therefore, the present invention provides an insulating member that covers and insulates the main body of the temperature fuse together with the lead wire, and a fixing member that clamps and fixes the main body from above the insulating member. The purpose is to insulate the exposed portion of the lead wire, maintain an appropriate distance between the main body of the temperature fuse and the fixing roller, stabilize the position of the main body, and eliminate leaks and short circuits caused by the lead wire.

[Structure of the Invention] In order to achieve the above object, the present invention includes a fixing roller rotatably supported by a frame, a pair of fixing rollers provided close to the roller, and connected to a main body portion and both ends of the main body portion, respectively. A fixing device comprising: a temperature fuse having a lead wire; an insulating member that covers and insulates a main body of the temperature fuse together with a pair of lead wires; A fixing member fixed to the frame is provided.

Hereinafter, the present invention will be explained based on the drawings.

1 to 4 are diagrams illustrating an embodiment of a fixing device according to the present invention. Incidentally, in FIG. 1, the same members as those in the conventional fixing device shown in FIG. 5 are given the same numbers, and redundant explanation will be omitted.

First, the configuration will be explained. When the members shown in FIG. is rotatably supported.

In FIGS. 1 and 2, 40 is a temperature fuse, and the temperature fuse 40 includes a main body 41 and a pair of metal rod-shaped lead wires 4 connected to both ends of the main body 41, respectively.
It has 2. On the other hand, 43 is a heat-shrinkable insulating tube, and the insulating tube 43 has a continuous heat resistance of 200°, for example.
C1 consists of a silicone tube with a wall thickness of 0.5 mm,
Double layered. Then, the main body 41 and lead wire 42 of the temperature fuse 40 are fitted into the insulating tube 43, and a round terminal 44 is fixed to the tip end 42a of the lead wire 42, respectively. Next, the insulating tube 43 is heated and contracted, the main body 41 and the lead wire 42 are covered and insulated by the insulating tube 43, and the temperature fuse assembly 45 is assembled. That is, the insulation tube 4
3 connects the main body 41 of the temperature fuse 40 to a pair of lead wires 4
It has a function as an insulating member to cover and insulate together with 2.

The temperature fuse assembly 45 assembled in this way is fixed to the frame 1 by the fuse fixing member 46, as shown in FIG.
is provided close to the fixing roller 3. That is, in FIG. 2, the above-mentioned fuse fixing member 46 has a semi-cylindrical cover portion 46a having approximately the same curvature as the outside of the insulating tube 43 of the temperature fuse assembly 45, and protrudes downward in the figure from the cover portion 46a. Bifurcated legs 46b
Consisting of As shown in FIG. 3, the legs 46b hold the main body 41 of the temperature fuse 40 from above the insulating tube 43, and the cover part 46a covers the main body 41 from above the insulating tube 43. Then, the leg portions 46b are respectively fitted into the fixing holes 1a of the frame 1 in FIG.
Fixed. At this time, the cover portion 46a of the fuse fixing member 46 holds the main body 41 of the temperature fuse 40 from above the insulating tube 43 together with the frame 1, and
1 is fixed to the frame 1 in the vertical direction, and further, as described above, the legs 46b sandwich the main body 4I of the temperature fuse 40 from above the insulating tube 43, so that the main body 41 is fixed to the frame 1 laterally. Therefore, the distance between the main body 41 and the fixing roller 3 is maintained appropriately, and the main body 41 is stably positioned. That is, the fuse fixing member 46 has a function as a fixing member that clamps and fixes the main body part 41 of the temperature fuse 400, which is covered with the insulating tube 43 as an insulating member, to the frame 1.

Further, as shown in FIG. 3, the lead wire 42 of the temperature fuse 40 fixed to the frame l by the fuse fixing member 46 is bent from the fuse fixing member 46 together with the insulating tube 43, so that the lead wire 42 is connected to the fixing roller 3. It is connected via screws 47 in a spaced-apart manner to the temperature fuse terminals 28, 29 shown in FIG.

Note that since the fuse fixing member 46 is closest to the fixing roller 3 heated by the heater 20, it is made of heat-resistant material,
For example, the cover part 46 of the heater fixing member 46 is made of heat-resistant resin, and as shown in FIGS.
In order to bring the main body part 41 as close to the ambient temperature inside the apparatus as possible, a temperature fuse 40 is installed opposite the fixing roller 3.
An opening 46d that is slightly larger than the main body 41 is formed.

Next, the effect will be explained.

In this embodiment, the main body 41 and lead wire 42 of the temperature fuse 40 are covered and insulated by the insulating tube 43, and the main body 41 of the temperature fuse 40 is held from above the insulating tube 43 by the fuse fixing member 46, and the frame Fixed. Further, the lead wire 42 is bent so as to be separated from the fixing roller 3. For this reason,
Even if the distance between the main body portion 41 and the fixing roller 3 is an appropriate distance of, for example, 31 Wl, there is no exposed portion of the lead wire 42 and the distance between the lead wire 42 and the fixing roller 3 is kept large. Leakage or short circuit of power supply current caused by damage to the heater 20 of the fixing roller 3 is prevented.

Further, the main body portion 41 is held by the insulating tube 43 and is fixed to the frame 1 by being clamped from above the insulating tube 43 by the fuse fixing member 46.

Therefore, the main body part 41 is fixed in the vertical and horizontal directions, and the distance between the main body part 41 and the fixing roller 3 is maintained at an appropriate distance, for example, in the third direction.
Fixed.

In this way, in this embodiment, the main body 4 of the temperature fuse 40
an insulating tube 43 that covers and insulates 1 together with a lead wire 42; and a main body 41 covered with the insulating tube 43.
Fuse fixing member 46 that clamps and fixes to frame 1
and , it is possible to insulate the exposed part of the lead wire 42, maintain the proper distance between the main body part 41 and the fixing roller 3 at a predetermined distance, and stabilize the position of the main body part 41. When the heater 20 is damaged, the lead wire 4
It is possible to eliminate leaks and short circuits caused by the exposure of No. 2.

Effect C] According to the present invention, an insulating member that covers and insulates the main body of the temperature fuse together with the lead wire, and a fixing member that clamps the main body from above the insulating member and fixes it to the frame are provided. In addition to insulating the exposed portion of the lead wire, the distance between the main body and the fixing roller can be maintained appropriately, the position of the main body can be stabilized, and leaks and short circuits caused by the lead wire can be eliminated.

[Brief explanation of the drawing]

1 to 4 are views showing one embodiment of the fixing device according to the present invention, FIG. 1 is an exploded perspective view thereof, FIG. 2 is an exploded perspective view of its temperature fuse assembly, and FIGS. Figures 5 to 7 are diagrams showing the conventional fixing device, Figure 5 is an exploded perspective view thereof, Figure 6 is an exploded perspective view of the temperature fuse assembly. , FIG. 7 shows the temperature fuse assembly in a fixed state. DESCRIPTION OF SYMBOLS 1... Frame, 3... Fixing roller, 40... Temperature fuse, 41... Main body, 42... Lead wire, 43 ...Insulation tube (insulation member), 46...
... Fuse fixing member (fixing member).

Claims (1)

[Claims] A fixing device including a fixing roller rotatably supported by a frame, and a thermal fuse that is provided close to the roller and has a main body portion and a pair of lead wires connected to both ends of the main body portion, respectively. An insulating member that covers and insulates the main body of the thermal fuse together with a pair of lead wires, and a fixing member that clamps and fixes the main body of the thermal fuse covered with the insulating member to the frame. fixing device.