JPS5934313B2 - Teichiyakouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device in an electrophotographic copying machine that uses a fixing roller for heating and fixing a heat-adhesive visible image on a copying material.

Conventionally, a fixing device using a pair of fixing rollers of this type includes a fixing roller for fixing a toner image on a copy material and a pressure roller for pressing the copy material against the fixing roller.

The surfaces of these fixing rollers and pressure rollers are coated with an anti-offset material such as silicone rubber or Teflon resin so that the toner image on the copying material is not offset. In addition, as heating means for the fixing roller and the pressure roller, the roller is shaped like a pipe and a heating means such as an infrared lamp is provided inside the pipe, or the roller surface is provided with a heating means such as an infrared lamp in close proximity. ing. This type of fixing device has excellent features such as being highly safe when the copying material jams as a fixing means, and having good thermal efficiency and low power consumption.On the other hand, in order to improve fixing performance, the roller surface temperature is raised. If the anti-offset material on the surface of the roller deteriorates, the toner image on the copy material tends to offset toward the fixing roller, and in extreme cases, the copy material may wind around the fixing roller.

For this reason, it has been conventional practice to apply an anti-offset material such as silicone oil to the surface of the fixing roller. On the other hand, when a fixing roller coated with an elastic material such as silicone rubber is used, the fixing roller pressed by the pressure roller will not only change depending on changes in pressure, but also when maintaining a constant pressure. Also, the radius of rotation changes due to swelling of silicone rubber due to silicone oil, thermal expansion due to changes in heating temperature, wear due to friction between rollers, etc.

Therefore, when both the fixing roller and the pressure roller are forcibly driven, a difference in circumferential speed occurs between the fixing roller and the pressure roller, which disturbs the fixed image on the copy material and causes wrinkles on the copy material. becomes. To prevent this, conventionally a special drive mechanism such as a differential gear mechanism was used to match the circumferential speed, but in order to avoid this complicated mechanism, it was necessary to forcibly drive either the fixing roller or the pressure roller. , one side was driven by surface friction force. However, when either the fixing roller or the pressure roller is driven, when applying silicone oil to the fixing roller and performing fixing,
When the coating layer of silicone oil is thick, there is a drawback that slips are likely to occur between the fixing roller and the pressure roller due to the silicone oil film.

The present invention seeks to eliminate the above drawbacks and prevent slippage between the rollers.

That is, the present invention provides a first roller, a third roller that is in pressure contact with the first roller and conveys the copying material between the first roller and fixes the developed image on the copying material, and pressure contact and the third
a second roller that presses the first roller between the rollers;
and a coating means for applying an offset prevention material to the surface of the roller, wherein a coating layer of the offset prevention material for preventing offset of the developed image is formed on the surface of the first roller, wherein the second and second rollers It has a driving means for forcibly driving the second and third rollers so that the circumferential speeds of the three rollers are the same, and the first roller is moved between the surfaces of the second and third rollers and the first roller. This is a fixing device characterized by driven rotation by frictional force.

The present invention will be explained below with reference to the drawings.

In FIG. 1, a fixing roller 1 as a first roller is an elastic roller having a silicone rubber layer.

Pressure roller 2 as a third roller below the fixing roller 1
is a rigid roller whose surface is made of a gold-layered pipe with good thermal conductivity and coated with a material with good mold release properties such as Teflon (trade name), and is equipped with a heating source 3 such as an infrared lamp inside. The pressure roller 5 as a second roller above the fixing roller 1 is a rigid roller made of a metal pipe with good thermal conductivity, and is provided with a heating source 6 such as an infrared lamp inside. A sprocket foil 4 is attached to the end of the pressure roller 2, and a sprocket foil 4 is attached to the end of the pressure roller 2.
A sprocket wheel 7 is fixed to the end of the roller, and a chain belt 8 causes both rollers to rotate in the same direction.

At this time, the number of teeth of the sprocket wheels 4 and 7 must be selected so that the pressure rollers 2 and 5 rotate at the same peripheral speed. When drive is forcibly transmitted to one of the pressure rollers 2 and 5 by a drive source (not shown), the upper and lower pressure rollers 2 and 5 rotate at the same circumferential speed due to the rotation of the chain belt 8. Fixing roller 1 pressed from above and below
is driven by the surface friction force.

Silicone oil 1 used as offset prevention material
0 is drawn up from inside the container 11 by the rotating roller 12 and applied to the surface of the pressure roller 5 by the felt 13 in contact with the roller 12. Silicone oil 10 applied to the surface of the pressure roller 5 is supplied to the fixing roller 1 as the pressure roller 5 rotates. 14 is a presser plate for the felt 13.

A copying material 16 having a toner image 15 is transferred to a fixing roller 1
and the pressure roller 2 and are fixed. When the fixing device is not fixed or the fixing device is not in use, in order to prevent the fixing rubber roller 1 from deforming, the pressure of the pressure rollers 2 and 5 on the fixing roller 1 is released as shown in FIG. Rotate while touching.

In this case, the chain belt 8
An idler (not shown) may be installed at an appropriate location to adjust the tension of the. In addition, the circumferential length of the chain belt 8 is set according to the light contact state (pressure release state) as shown in FIG. 1a, and the pressure contact state (pressure released state) as shown in FIG.
When the chain belt 8 is under pressure (in a pressurized state), even if there is slack in the chain belt 8, as long as it is less than 1 pitch (pitch 6.35 mm in the case of a push chain), the chain 8 will rotate without coming off from the teeth of the sprocket foil. can continue. As described above, in the present invention, the upper and lower pairs of rigid rollers are driven at the same circumferential speed in a three-roller configuration, so even if a lubricating film such as silicone oil is formed on the surface of the elastic rubber roller, the roller will not slip and will not slip. Since it can be rotated and the paper feeding speed is constant, the fixing operation can be performed without changing the fixing conditions.

2 to 5 illustrate a pressing method using a toggle joint mechanism for pressing the fixing roller and a pair of pressure rollers from a light contact state to a pressure contact state.

In FIGS. 2 and 3, rollers 17, 18, and 20 have the same structure and function as rollers 1, 2, and 5 in FIG. 1, respectively, and are a fixing rubber roller and two pressure rollers.

Reference numerals 29 to 31 indicate a toggle joint mechanism, whose arms 28 and 31 have one end attached to the machine frame 27 with shafts 32 and 33, and the other end attached to the operating arms 29 and 30 with pins 34 and 35.
, 36.

The operating arm 29 faces the cam 37, and the operating arm 30 is interlocked with a bearing 40 via a piston 38 and a compression spring 39. The cam 37 is engaged with and disengaged from the shaft 42 via a clutch 41. 43
An electromagnetic plunger operates the clutch 41, and a clutch controller 44 swings about a shaft 45 by the electromagnetic plunger 43.

The bearing 40 is attached to the machine frame 27 by a shaft 46 and supports the shaft 20' of the pressure roller 20.

A sprocket wheel 47 and a gear 48 are disposed on the shaft 46, and the gear 48 meshes with a gear 49 mounted on the shaft 20' of the pressure roller 20.
The rotation is transmitted to the pressure roller 20. Lower pressure roller 1
The shaft 18' of 8 is supported by a bearing 50 fixed to the machine frame 27. Also, a gear 51 is fixed on the shaft 18'.
The sprocket wheel 53 engaged with the gear 52 causes the upper pressure roller 20 to rotate at the same circumferential speed as the lower pressure roller 18 through the chain 54 to the sprocket wheel 47 . The rotation of the chain 54 is further directed to the camshaft 42 by a sprocket wheel 55, and to the discharge port roller shaft 2 through a sprocket wheel 56, a gear 57, and a gear 58.
Rotate 6.

The cam 37 is normally in the position shown in FIG. 4 and does not act on the toggle joint mechanisms 29-31.

Therefore, when the toggle joint mechanism is in the state shown in the figure, the force pushing the roller 20 downward is weak, and the rollers 17, 18
, 20 are in a light contact state as shown in FIG. In Figure 3, 2
3 is a hole provided in the machine frame 27 for vertical movement of the shaft 22. The roller 18 is forcibly driven from a drive source (not shown), and its rotation is transmitted to the roller 20, camshaft 42, and discharge rollers 24, 25 by rotation of the chain 54 via a gear train and sprocket. When the pressurizing operation signal is transmitted to the fixing device, the electromagnetic plunger 43 is excited, and the controller 44' engages the spring clutch 41 having a coil spring inside.
By moving further apart, the clutch 41 operates and the cam 3
7 is engaged with the shaft 42.

Since the cam 42 pushes up one end of the actuating arm 29 of the toggle mechanism, the toggle mechanism enters the state shown in FIG. 5 while its movement is restricted by the arms 28 and 31, and pushes down the bearing 40 via the piston 38 and spring 39. The bearing 40 pivots about the shaft 46, and the roller 20 is pushed down, pushing the resilient roller 17 downward in FIG. 2 and into the pressure contact state of FIG. 5. At this time, since the gear 48 that transmits rotation to the roller 20 is on the fulcrum shaft 46, it always meshes with the gear 49 on the roller 20 to transmit rotation. Movement of the toggle mechanism is detected by a sensing element (not shown), which cuts the current to the electromagnetic plunger 43, disengages the clutch 41, and maintains the cam 37 in that state.

When the fixing work is completed and a pressure release signal is input, the electromagnetic plunger 43 acts again, and the clutch 41 engages to release the cam 37.
4 to return the toggle joint mechanism to the state shown in FIG.

After returning, the clutch 41 is disengaged and the cam 37 is stopped. As mentioned above, when the pressure roller pivots about a point on the machine frame as a fulcrum, if you install a gear on the fulcrum that meshes with the gear on the pressure roller, the engagement between the gears will always remain the same up and down. A pressure roller can be driven.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a cross-sectional view when not fixing, FIG. 3 is a cross-sectional view when fixing, FIG. 4 is a configuration diagram of the control mechanism, and FIG. A configuration diagram of a mechanism during fixing. 1... Fixing roller, 2... Pressure roller, 3... Heat source, 5... Pressure roller ~
8... Chain belt.

Claims (1)

[Claims] 1 a first roller, a third roller that is in pressure contact with the first roller and transports the copying material between the first roller and fixes the developed image on the copying material; An offset prevention device that prevents offset of a visible image on the surface of the first roller, comprising a second roller that presses the first roller between the rollers and a coating device that applies an offset prevention material to the surface of the roller. In the fixing device where the coating layer of the material is formed,
The second roller is rotated so that the circumferential speeds of the second and third rollers are the same.
, comprising a driving means for forcibly driving a third roller, and the first roller is driven to rotate by mutual surface friction force between the second and third rollers and the first roller. Fusing device.