JPH04318585A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent the operability of transparency material and image quality from being deteriorated by changing an oil application amount to a fixing roller from an oil applying means according to the kind of the transcription material and to improve the consuming efficiency of oil by eliminating the needless oil which is taken out with a transcription material. CONSTITUTION:The hook of a spring 7 is varied to a position 71 and a position 72. Namely, when the hook is at the position 72 where the oil application amount from an oil felt 4 to the fixing roller 1 is changed, force generated by the spring 7 is larger than when it is at the position 71, so that the press-contact force of the oil felt 4 is large and an oil oozing amount from the oil felt 4 is increased. Therefore, the oil application amount to the fixing roller 1 becomes large. That is, when the hook is at the position 72, a plain paper is set as the transfer material and when it is at the position 71, the transparency is set as the transcription material.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device, and more particularly to a fixing device using a heated roller and a release agent (hereinafter referred to as oil).

0002

[Prior Art] Conventionally, in electrophotographic copying machines, electrostatic printers, etc., a toner image formed on a photoreceptor as a latent image carrier is transferred onto a recording material and then subjected to heat or pressure. The image is fixed by a fixing device having a fixing roller. In this type of fixing device, in order to prevent the toner image from being offset to the fixing roller and to easily peel off the transfer paper from the fixing roller, the fixing roller is coated with a release oil such as silicone oil. It is common practice to apply . FIG. 5 shows a fixing device having such a configuration. In the figure, the fixing roller 1 and the pressure roller 2 are heated by an internal heater (not shown) and are in contact with each other under constant pressure, and are rotating in the direction of arrow A. A transfer material T having an image (toner image) on its surface is sent in the direction of arrow B and passes between a fixing roller 1 and a pressure roller 2 by a guide 3. Before the transfer material T passes through the fixing roller 1 and the pressure roller 2, the oil felt 4 whose one end is immersed in the oil 9 in the oil pan 8 is rotated by the felt actuating cam 6 by half a rotation (as indicated by the solid line in the figure). (changes from shape to dotted line shape) Under the force of spring 7,
It comes into contact with the fixing roller 1 (as indicated by the dotted line in the figure) and applies oil to the fixing roller 1.

The above-mentioned oil application operation is always performed before the transfer material T passes between the fixing roller and the pressure roller, regardless of the type of the transfer material T (for example, plain paper, transparency, or label paper). . However, in order to compensate for poor fixing due to differences in heat capacity depending on the material of the transfer material T, the amount of heat supplied to the transfer material T from the fixing roller and pressure roller may be increased (lower the speed of the fixing roller, heaters in both rollers) (increase in power supply).

0004

[Problems to be Solved by the Invention] However, in the above conventional example, the transfer material is transparent (hereinafter referred to as trapen).
In this case, there were the following drawbacks. First of all, the surface of the trap pen is smooth and there are very few pores that oil can enter on the surface compared to plain paper, so a large amount of oil remains on the surface of the trap pen compared to plain paper and does not come out from the fixing roller. come. Furthermore, while the trap pen is passing through the fixing roller, oil tends to accumulate between the trap pen and the fixing roller, and the accumulated oil may leak out the image on the trap pen. FIG. 6 shows these phenomena. 41 is an oil layer formed on the fixing roller 1 by oil felt. The oil layer 41 forms an oil pool 42 between the fixing roller 1 and the trap pen T because the oil does not go to the pressure roller 2 side (in the direction in which it soaks into the trap pen T). 43 is the residual oil on Trapen T, which is mainly located in areas where there is no toner image.

[0005] When a trap pen is used as a transfer material, the above-mentioned phenomenon occurs, which significantly impairs the operability of the trap pen after fixing (difficult to handle due to oil) and image quality (desired image cannot be obtained). It was a loss.

[0006]

[Means for Solving the Problems] The present invention solves the above problems by providing an oil application means with a means for changing the amount of oil applied to the fixing roller and operating it according to the type of transfer material. This prevents deterioration in operability of the trap pen and image quality after fixing, which occurred in the case of .

[0007]

Embodiment Next, a first embodiment of the present invention will be explained using FIGS. 1 and 2. In FIG. 1, the oil felt 4 is in contact with the fixing roller 1 by the force of a spring 7, and the pressing force is determined by the spring 7. The spring 7 has one end hooked to the oil felt 4 and a hook 53 of the support 5, and the other end hooked to a hook 71. The hook 71 is the hook support 7
3. The hook moving member 74 can move up and down in the drawing to the position 72 (dotted line). FIG. 2 shows the hook movement mechanism, and is a view taken from the direction of arrow C in FIG. 1. The movement range of the hook 71 is limited to the hook support 73.
It is located on the oblique surface 74-a (two places) of the hook moving member 74, and is determined by the elongated holes 73-a (two places). The hook moving member 74 is moved by the regulating pin 75 and the elongated hole 74-b as shown in FIG.
The hook moving member 74 is movable up and down and left and right, and the hook moving member 74 is located at D in the figure.
Or by moving in the direction of the arrow E, the hooks will move to 71, 72.
take the position. Note that the hook moving member 74 is moved in directions D and E by a spring 76 and a solenoid 77, respectively.

In FIG. 1, the position of the hook of the spring 7 is 71.
and 72, the amount of oil applied to the fixing roller 1 by the oil felt 4 can be changed. Since the pressing force of the oil felt 4 is large and the amount of oil seeping out from the oil felt 4 is large, the amount of oil applied to the fixing roller 1 is large. In other words, when the hook position is 72, the transfer material is set to plain paper,
When the hook position is 71, it is sufficient to set the transfer material as a trap pen.

[0009] When the transfer material is plain paper or a trap pen, the appropriate amount of oil to be applied can be determined experimentally in advance, so the spring pressure can be determined based on the determined value.

Next, another embodiment of the present invention is shown in FIG. In FIG. 3, reference numeral 10 denotes a member for regulating the amount of movement of the felt support 5, which is supported and movable in the same manner as the hook moving member 74 in FIG. 2 at the front and back in the drawing. According to the movement of the regulating member 10, the regulating portions 10-a and 10-b come out above the felt support 5, and the felt support 5 is moved to the position 5-a in the figure.
(solid line) and 5-b (dotted line). At that time, the contact states of the oil felt 4 with the fixing roller 1 are as shown by 4-a and 4-b, respectively.

Comparing the contact areas of 4-a and 4-b with the fixing roller 1, 4-a is smaller, which means that 4-a requires less oil application. In other words, when the oil felt 4 is 4-a, Trapen is selected as the transfer material, and when the oil felt 4 is 4-b, plain paper is selected as the transfer material.

FIG. 4 shows another embodiment of the present invention, and shows the time required to bring the oil felt 4 into contact with the fixing roller 1.

Conventionally, the oil felt 4 was applied in advance (at t4 in the figure) to coincide with the time when the trap pen passes the fixing roller.
(In Figure 1, the distance from the oil felt grounding part to the fixing roller nip part divided by the circumferential speed of the fixing roller) is brought into contact with the ground, and the state is maintained for the same time as t1 for the trap pen to pass through the fixing roller (t3 dotted line in the figure). I've been doing it. In the embodiment of the present invention (solid line t2 in the figure), the grounding start timing is the same as before, but the grounding holding time is shortened. This is to reduce the amount of oil applied by shortening the time the oil felt is in contact with the ground.

[0014] In the description of the embodiments of the present invention, an example was shown in which oil felt was used as the form of oil application, but the present invention can also be practiced in other forms (for example, roller application). It goes without saying that the aforementioned effects can be obtained in the same way.

[0015]

[Effects of the Invention] As explained above, according to the present invention,
Since the appropriate oil can be supplied for trap pen fixing, it is possible to prevent the deterioration in operability of the trap pen and image quality that has occurred in the past. Another effect of the present invention is that the amount of oil applied to all types of transfer material can be optimized, eliminating the oil that was previously unnecessarily taken out with the transfer material, improving oil consumption efficiency.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram seen from direction C in FIG. 1;

FIG. 3 is an enlarged sectional view of a device according to a second embodiment of the present invention.

FIG. 4 is a control diagram of a device according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a conventional device.

FIG. 6 is a diagram of a conventional device when a trap pen passes through the device.

[Explanation of symbols]

1 Fixing roller 2 Pressure roller 3 Guide 4 Oil felt 5 Oil felt support 6 Oil felt support moving cam 7 Oil felt biasing spring 8 Oil pan 9 Oil 10 Regulating member (for oil felt support 5) 71
Hook (for spring 7) 74 Hook moving member t1 Trap pen fixing roller passing time t2 Felt contact time according to the present invention t3 Conventional felt contact time t4 Felt contact start time

Claims (4)

[Claims] 1. In a fixing device having a fixing roller, a pressure roller, and a means for applying oil to the surface of the fixing roller, the amount of oil applied from the oil applying means to the fixing roller can be controlled depending on the type of transfer material. A fixing device characterized by being changeable. 2. The fixing device according to claim 1, wherein the method for changing the amount of oil applied includes changing the pressing force of the oil application means against the fixing roller. 3. The fixing device according to claim 1, wherein the method for changing the amount of oil applied includes changing the contact area between the oil applying means and the fixing roller. 4. The fixing device according to claim 1, wherein the method for changing the amount of oil applied includes changing the contact time between the oil applying means and the fixing roller.