JPH01298383A - Toner image fixing device - Google Patents

Abstract

PURPOSE:To simplify a mechanism and to reduce a production cost by providing an electromagnetic means for selecting a working state where fixing means press-contact and a non-working state where they do not press-contact. CONSTITUTION:The title device is provided with the electromagnetic means 18 for selectively setting both an upper fixing means 2 and a lower fixing means 4 in the working state where both of them press-contact and the non-working state where both of them do not substantially press-contact. When the electromagnetic means 18 is de-energized, the upper fixing means 2 and the lower fixing means 4 are kept in the non-working state and when said means 18 is energized, the upper fixing means 2 and the lower fixing means 4 are made to be in the press-contacting state with magnetic attraction force. Thus, the upper fixing means and the lower fixing means can be selectively set to be in the working state and the non-working state with a comparatively simple constitution. Moreover, specified press-contacting force can be obtained all over the fixing means in substance in the working state.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a toner image fixing device that fixes a toner image formed on a sheet member as a permanent image on the surface thereof.

<Prior Art> Conventionally, image generating machines such as electrostatic copying machines are equipped with toner image fixing devices for fixing toner images formed on sheet members such as copy paper. Such a toner image fixing device generally includes an upper fixing means composed of an upper roller and an upper fixing means composed of a lower roller.
The toner image is fused to its surface while being conveyed between the lower rollers.

However, the conventional toner retention device has the following problems that need to be solved.

First, in this type of fixing device, in order to prevent deformation of the rollers, the 1-roller and the lower roller are normally held in a non-operating state (in a state in which the two rollers are not substantially in pressure contact 78); During fixing, both rollers are brought into an active state (both rollers are in pressure contact), but the mechanism for selectively bringing both rollers into the non-working state and the working state is complex and the manufacturing cost is high. It gets expensive.

Second, in this type of fixing device, a pressure contact force is applied between both ends of the L roller and the lower roller, and the pressure contact force maintains both ends in an operating state. Therefore, it is possible to obtain a pressure contact force of 1 minute at both ends of both rollers, but it is not possible to obtain a sufficient pressure contact force at the middle part of both rollers, and the toner is removed at the middle part of both rollers in the axial direction. Poor image fixation is likely to occur. On the other hand, in order to solve the above-mentioned disadvantages, it is necessary to change the outer shape of the upper roller and lower roller to a special shape (
The diameter of the roller may be gradually increased toward the center in the axial direction of the roller, but it is not easy to manufacture a roller with a special shape, and the manufacturing cost is also high.

<Object of the Invention> The present invention has been made in view of the above facts, and its main purpose is to selectively put the upper fixing means and the upper fixing means into the working state and the non-working state with a relatively simple structure. Furthermore, it is possible to obtain a predetermined pressing force over substantially the entire width of these refixing means in the active state.

An object of the present invention is to provide an excellent toner image fixing device.

(Eleven points of the invention) According to the present invention, an upper fixing means and an upper fixing means are provided which cooperate with each other, and a toner image is formed by conveying a sheet member between the upper fixing means and the upper fixing means. A toner image fixing device fixed on the surface of a sheet member, comprising electromagnetic means for selectively causing the upper fixing means and the upper fixing means to be in an operating state in which both are in pressure contact and in a non-operating state in which both are not in pressure contact. When the electromagnetic means is deenergized, the upper fixing means and the r fixing f stage are held in the inactive state, and when the electromagnetic means is energized, the magnetic attraction generated by the electromagnetic means is maintained. There is provided a toner image fixing device characterized in that the upper fixing means and the r fixing means are brought into the above-mentioned pressure contact state by force.

<Specific examples of the invention> Further details will be given below with reference to the accompanying drawings.

First Specific Example A first specific example of the toner image fixing device according to the present invention will be described with reference to FIGS. 1 and 2. FIG.

1 and 21A, the illustrated fixing device includes an upper roller 2 constituting an upper fixing means that acts on one side (for example, the negative side) of a sheet member such as copy paper, and an upper roller 2 that constitutes an upper fixing means that acts on one side (for example, the negative side) of a sheet member such as copy paper, and the other side (for example, the lower side) of the sheet member. ) is provided with a lower roller 4 constituting an upper fixing means.

The upper roller 2 includes a hollow cylindrical roller body 6. The roller body 6 can be made of a non-magnetic material such as aluminum. Substantially the entire circumferential surface of the roller body 6 is covered with a fluorocarbon resin layer 8 such as Teflon. This roller body 6 is supported as shown in FIG. The fixing device includes a pair of support plates lO arranged at intervals.
and 12, one end of the roller body 6 (the left end in FIG. It is rotatably attached to the support plate 12 via. Both ends of the roller body 6 protrude outward through the support plates 10 and 12, and a transmission member 14 such as a gear is fixed to the other end protruding through the support plate 12, and this transmission member 14 is connected to the electric motor. The device is drivingly coupled to a driving source (not shown) such as the like. Therefore, when the drive source is energized, the upper roller 2 is rotationally driven in the direction shown by the arrow 16 (FIG. 1) via the transmission member 14.

Inside the roller body 6 of the seven rollers 2, an electromagnetic means 18 and a heating means 20 are arranged. The illustrated electromagnetic means 18 comprises a core body 22 extending over substantially the entire axial length of the roller body 6 . The core body 22 has an elongated rectangular shape,
A plurality of coils 24 are wound around the outer peripheral surface (eg, wound clockwise when viewed from above in FIG. 2).

The core body 22 can be made of a material with high magnetic permeability, such as an iron alloy. Support shaft portions 26 and 28 are provided at both ends of the core body 22, and project from both sides.
The hanging portion 3 provided on one of the support shaft portions 26 or the support plate 10
0, and the other support shaft portion 28 is attached to the hanging portion 32 provided on the support plate 12. This electromagnetic means 18
is disposed at the lowest part of the upper roller 2, in other words, facing the nip area between the troller 2 and the lower roller 4. Further, the illustrated heating means 20 is composed of a heating lamp 34. The heating lamp 34 is disposed close to the inner surface of the roller body 6 on the upstream side of the location where the electromagnetic means 18 is disposed when viewed in the direction of rotation of the upper roller 2 shown by the arrow 16. One end of this heating lamp 34 is supported by the vertical part 30 of the support plate 10,
The other end portion is supported by the hanging portion 32 of the other support plate 12 . A reflecting plate 36 is further provided inside the troller 2 to reflect the heat from the heating lamp 34 toward the inner surface of the roller body 6. Also, on the outside of the -fZ roller 2, there is provided a reflector plate 36 that reflects the heat from the heating lamp 34 toward the inner surface of the roller body 6. A working separation pawl 38 is also provided.

The troller 4 includes a hollow cylindrical roller body 40.

Specifically, the roller body 40 is somewhat shorter than the roller body 6 of the troller 2 and is arranged between the support plates IO and 12. The roller body 40 can be made of a ferromagnetic material, such as iron. Substantially the entire circumferential surface of the roller body 40 is
It is covered with a rubber layer 42 such as silicone rubber.

This roller body 40 is supported as shown in FIG. That is, both ends of the roller body 40 are supported by bearing members 44 and 46.
It is rotatably supported by a support shaft 48 via. The support shaft 48 extends between the support plates 10 and 12, and has one end attached to the support plate 10 and the other end attached to the other support plate 12. In the specific example, a vertically elongated hole 50 is formed in the support plate 10, and one end of the support shaft 48 is received in the hole 50 so as to be movable along the hole 50. Also, in the support plate 12, -E downwardly elongated holes 5 are provided.
2 are formed, and the other end of the support shaft 48 is received in the hole 52 so as to be movable along the hole 52. Therefore,
The lower roller 4 moves upward by one point between the position where both ends of the support shaft 48 contact one end (T end) of the holes 50 and 52 and the position where both ends contact the other end (upper end) of the holes 50 and 52. It is mounted so as to be movable in the direction, that is, in the direction toward and away from the seven rollers 2.

Referring to FIG. 1, a sheet member (not shown) such as copy paper that is conveyed in the direction shown by arrow 54 is placed on the L side of upper roller 2 and lower roller 4.・A guide plate 56 is provided to guide the pumping area, and both rollers 2 and 4 are provided.
A guide plate 58 is provided on the downstream side to guide the sheet members discharged from both rollers 2 and 4 further downstream.

The electromagnetic means 18 and the heat lamp 34 are operated and controlled by a control system shown in FIG. That is, a detection switch 60 for detecting the sheet member is provided below the guide plate 56. The detection arm 60a of the detection switch 60 is connected to the guide plate 5.
1 protrudes to one side through an opening 62 formed in 6, and is brought into the state shown by the two-dot chain line in the first part by the action of the sheet member (thereby, the switch 60 is closed).

The signal from this switch 60 is fed to control means 64, which may consist, for example, of a microprocessor. Further, signals from a main switch 66 and a copy start switch 68 of, for example, an electrostatic copying machine to which the fixing device is applied are also sent to the control means 64. Further, a current A adjustment means 70 for adjusting the current supplied to the electromagnetic means 18 by 3I is also provided, and a signal from the first stage 70 of current adjustment is also provided to the control means 64.
is supplied to

The effects of the fixing device described above will be explained as follows.

When the main switch 66 is closed and then the copy start switch 68 is closed, a predetermined copying process is performed and the heat lamp 34 is energized by the activation signal from the control means 64 (thereby, the heat lamp 34 is (to maintain the peripheral surface of the roller 2 at a predetermined temperature), and a driving source (not shown)
The upper roller 2 is driven to rotate in the direction shown by the arrow 16.

When the sheet member that has undergone the copying process and has a toner image formed on one side is conveyed to the location where the detection switch 60 is installed,
This sheet member allows the detection arm 60 of the switch 60 to
A is pressed, and the switch 60 changes from open to closed. Thus, based on the detection signal from the switch 60, the control means 6
4 energizes the electromagnetic means 18 and supplies current to the coil 24. When the electromagnetic means 18 is energized, the roller body 40 of the lower roller 4 is magnetically attracted by the generated magnetic attraction force. 4 is biased toward the upper roller 2, and the seventh roller 2 and the lower roller 4 are partially in the non-operating state shown by the two-point line 'lcJ' in FIG. is located at the position shown by the two points 'lQ line), and is brought into the operating state shown in solid lines in FIG. 1 and shown in FIG. 2. In this operating state, the upper roller 2 and the lower roller 4 are held in pressure contact by the magnetic attraction, and thus, while the sheet member is conveyed between the upper roller 2 and the lower roller 4, the toner image is moved in the direction indicated by the arrow 1.
The lower roller 2 is rotated in the direction shown by arrow 6, and the lower roller 4 is driven in the direction shown by arrow 72. For example, since the magnetic attraction action acts over substantially the entire length of the upper roller 2 and the lower roller 4 in the axial direction, the pressure contact force is uniform over substantially the entire length of the contact area between the upper roller 2 and the lower roller 4. Therefore, it is possible to prevent partial fixation failure of the toner image.

In connection with this, (1) the outer shapes of the roller bodies 6 and 40 of the lower roller 2 and the lower roller 4 do not need to be made into a special shape, and may be a normal cylindrical shape, making manufacturing extremely easy.

Further, the roller body 6 of the upper roller 2 (actually the fluorine resin layer 8 existing on the outer peripheral surface) and the roller body 40 of the lower roller 4 (actually the rubber layer 42 existing on the outer peripheral surface) are brought into direct pressure contact. Therefore, a large force is not applied to the bearing members 14 and 16 supporting the first roller 2, the bearing members 44 and 46 supporting the roller body 40 of the lower roller 4, etc., as in the conventional case, and the upper roller 2 The drive is small and good,
Furthermore, the wall thicknesses of the roller body 6 of the upper roller 2 and the roller body 40 of the lower roller 4 can be made thinner than in the past, and in this connection, the so-called ohm-up time can also be shortened.

A predetermined period of time elapses after the rear end of the sheet member passes the switch 60 and releases the pressure of the detection arm 60a (the time required for the rear end of the sheet member to pass through the nip area between the upper roller 2 and the lower roller 4). ), the control means 64 stops energizing the electromagnetic means 18. As a result, the magnetic attraction acting between the electromagnetic means 18 and the roller body 40 of the lower roller 4 disappears, and the lower roller 4 moves to the lower position shown by the chain double-dashed line in FIG. 48 is held in this lowered position by abutting one end of the holes 50 and 52), and the upper roller 2 and lower roller 4 are held in the above-mentioned inactive state. In this non-acting state, the lower roller 4 is separated downward from the -E roller 2 and does not substantially exert -L action on its circumferential surface, and the pressure contact state between the upper roller 2 and the lower roller 4 is released, thus making it non-active. Deformation of the upper roller 2 and lower roller 4 during the fixing operation is prevented.

In such a fixing device, when the electromagnetic means 18 is energized, the current is supplied to the seven-stage electromagnetic coil 24 by the current adjusting means 70? By controlling f[, the pressure contact force between the upper roller 2 and the lower roller 4 can be adjusted. That is, when the amount of current supplied to the coil 24 by the current adjusting means 70 is increased (or decreased), the magnetic attraction force generated by the electromagnetic means 18 is also increased (or decreased), and thus, the magnetic attraction force generated by the electromagnetic means 18 and the roller body 40 is increased (or decreased). The magnetic attraction effect acting on the rollers increases (or decreases), and the pressing force between the rollers 2 and 4 increases (decreases). As described above, the pressing force between the -1-roller 2 and the lower roller 4 can also be easily adjusted.

In the specific example, the rubber layer 42 is provided on the outer circumferential surface of the roller body 40 of the lower roller 4, but if necessary, a magnetic layer or a magnetic layer may be provided, and a rubber layer shown in L may be provided on the outer circumferential surface. You can also do it. The magnetic layer may be made of, for example, synthetic rubber containing a large number of relatively small permanent magnet pieces (for example, synthetic rubber with the trade name "YRM-").
The magnetic layer can be formed from synthetic rubber containing a large number of relatively small ferromagnetic pieces such as iron. can.

In the specific example, the lower roller 4 is movable in the direction toward and away from the upper roller 2, or conversely, the upper roller 2 or the lower roller 4 is movable in the direction toward and away from the lower roller 4. It can also be made to be mobile.

Second Specific Example Next, a second specific example of the toner image fixing device according to the present invention will be described with reference to FIGS. 3 and 4. In the second specific example, the upper fixing means is composed of an endless upper belt 202, and the upper fixing means is composed of a lower roller 204. In FIGS. 206 and the upper frame body 2 attached to the lower frame body 206 so as to be openable and closable.
08, the lower roller 204 is attached to the lower frame body 206, and the upper belt 202 is attached to the upper frame body 208.

A pair of rollers 210 and 212 are rotatably mounted on the upper frame body 208 (the roller 212 is further movable over a predetermined range in directions approaching and separating from the lower roller 204), and the An upper belt 202 is wound between rollers 210 and 212. The upper belt 202 may be made of synthetic rubber, for example, and a fluorine resin layer such as Teflon is disposed on its outer peripheral surface.

Further, the pair of rollers 210 and 212 are made of a ferromagnetic material such as iron (although the roller 210 may be made of a non-magnetic material such as aluminum).

The lower roller 204 is rotatably attached to the lower frame body 206,
It is rotationally driven in the direction shown by arrow 214. The lower roller 204 includes a hollow cylindrical roller body 216 made of a non-magnetic material such as aluminum, and
A fluorine resin layer 218 such as Teflon is provided on substantially the entire outer peripheral surface of the roller body 216. This lower roller 20
4, an electromagnetic means 220 is disposed opposite to the row 212, and a heating lamp 2 is disposed upstream of the electromagnetic means 220.
22 and a reflecting plate 224 are provided. Electromagnetic means 22
0, the heating lamp 222, etc. may have substantially the same configuration as in the first specific example, and for example, their operation is controlled in the same manner as in the first specific example.

A pair of guide plates 226 and 228 are provided upstream of the upper belt 202 and the F roller 204 to guide the sheet member between the belt 202 and the roller 204.
2 and the lower roller 204, a pair of guide plates 230 and 232 are arranged to guide the sheet member further downstream. These guide plates 226, 228, 230 and 23
2 is attached to the r frame body 206.

When the electromagnetic means 220 is energized, the roller 212 is magnetically attracted by the generated magnetic attraction force, and therefore the roller 212 is attracted to the lower roller 204 by the magnetic attraction effect acting between the electromagnetic means 220 and the roller 212. The lower roller 204 and the upper belt 20 are moved in a direction closer to each other.
2 is maintained in the operating state shown in FIG. In this operating state, the lower running portion of the upper belt 202 is pressed against the outer peripheral surface of the lower roller 4 with a required pressure, and thereby the L belt 202 is stretched as required. In this operating state, when the lower roller 204 is rotationally driven in the direction shown by the arrow 214, the upper belt 202 is also moved in the direction shown by the arrow 230, and when the sheet member is conveyed between them, the surface of the sheet member is The formed toner image is fixed under heat and pressure by the heating action of the heating lamp 222 and the pressing action of the upper belt 202 and the lower roller 204.

On the other hand, when the electromagnetic means 220 is deenergized, the above-mentioned magnetic attraction effect disappears, and the above-mentioned tension on the upper belt 202 is somewhat relaxed (thereby, the roller 212 is moved closer to the lower roller 220).
04), the lower roller 204 and upper belt 202 are thus maintained in the inactive state shown in solid lines in FIG. In this non-operating state, the running portion of the upper belt 202 only contacts the circumferential surface of the lower roller 204 due to its own weight.
2 and the lower roller 204 are not substantially pressed against each other, and deformation of the lower roller 204 and the like is prevented. ? [With the means 220 in the de-energized state, when the upper frame body 208 is pivoted from the closed position shown by the solid line in FIG. 4 to the open position shown by the two-dot chain line in FIG. - The nip part between the lower running part of the belt 202 and the lower roller 204 is opened, and the L side of the troller 204 is fully opened, so that if a so-called jam occurs between the belt 202 and the lower roller 204, the jammed sheet can be removed. The parts can be easily removed.

In this second specific example as well, substantially the same effect as in the first specific example described in L is achieved.

That is, when the electromagnetic means 220 is energized, the roller 212 (
The width of this roller 212 substantially corresponds to the width of the L belt 202) and the roller body 216 of the R roller 204 has a magnetic attraction effect over substantially the entire length thereof, and therefore, the magnetic attraction action is applied to the roller body 216 of the old belt 202. is substantially uniformly pressed against the surface of the lower roller 204 in the width direction, thus preventing partial fixation failure. In addition, the upper belt 202 and the lower roller 20
4 are pressed substantially uniformly with sufficient pressure, the upper belt 202 can be moved as required simply by rotating the lower roller 204, and so-called deviation of the upper belt 202 is unlikely to occur. .

Although various specific examples of the toner image fixing device configured according to the present invention have been described above, the present invention is not limited to these specific examples, and various modifications may be made without departing from the scope of the present invention. Modifications and modifications are possible.

[Brief explanation of the drawing]

FIG. 1 is a simplified sectional view showing a first specific example of a fixing device according to the present invention and its vicinity. FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1. FIG. 3 is a simplified sectional view showing a second specific example of the fixing device according to the invention in an operating state. FIG. 4 is a simplified sectional view showing the fixing device of FIG. 3 in a non-operating state. 2... Upper roller 4... Lower rollers 6 and 40... Roller body 18... Electromagnetic means 22... Core body 24... Coil 64... Control means 72... Current adjustment 1 Step 202... Upper belt 204... Lower roller 220... Electromagnetic means tightening Patent attorney Tadashi Kishimoto Shuzen xπn 1st drawing 3rd drawing 4th figure

Claims (1)

[Claims] 1. An upper fixing means and a lower fixing means that cooperate with each other,
In a toner image fixing device in which a toner image is fixed on the surface of a sheet member by conveying the sheet member between the upper fixing means and the lower fixing means, the upper fixing means and the lower fixing means are both brought into pressure contact with each other. comprising an electromagnetic means for selectively bringing the electromagnetic means into an operative state and a non-operative state in which both are in substantially no pressure contact, and when the electromagnetic means is deenergized, the upper fixing means and the lower fixing means are maintained in the non-operative state; A toner image fixing device characterized in that when the electromagnetic means is energized, the upper fixing means and the lower fixing means are brought into pressure contact state by the magnetic attraction force generated by the electromagnetic means. 2. The electromagnetic means is disposed inside either the upper fixing means or the lower fixing means, the other of which includes a permanent magnet or a magnetic material, and when the electromagnetic means is energized, 2. The toner image fixing device according to claim 1, wherein the upper fixing means and the lower fixing means are maintained in the operating state by a magnetic attraction effect acting between the electromagnetic means and the other permanent magnet or magnetic body. 3. The electromagnetic means is provided with a current adjusting means for adjusting the current supplied to the electromagnetic means, and when the electromagnetic means is energized, the electromagnetic means is controlled by controlling the current supplied to the electromagnetic means. 3. The toner image fixing device according to claim 1, wherein a pressure contact state between the upper fixing means and the lower fixing means is adjusted.