JPS5855380Y2 - Heat roller fixing device - Google Patents

Description

[Detailed Description of the Invention] The present invention solves a defect that conventional heat roller fixing devices have, namely, that the toner that has accumulated and solidified on the blade etc. in the heat roller fixing device forms a surface coating on the fixing roller as the heat roller starts rotating. This is an improvement on the defect that had caused damage to the product.

A general heat roller fixing device consists of a fixing roller with a heat source,
It consists of a pressure roller that presses against this roller, and the surface of the fixing roller is coated with a film such as Teflon, which has good releasability, to prevent toner from adhering to the transfer body.

In addition, many pressure rollers have an elastic material such as silicone rubber with good mold releasability on their surface.

Now, in a fixing device with a relatively fast linear speed, if the surface of the fixing roller is not at a uniform temperature, it is noticeable that the fixed toner on the fixing material will be in an insufficiently fixed state in some parts. When the heat source was turned on, the roller was rotated to uniformly heat the roller surface.

On the other hand, the release properties of the fixing roller are not sufficient, so silicone oil is applied with a pad as an anti-offset liquid for l/ner, or toner stains, paper dust, etc. are scraped off with a blade. .

Further, in order to prevent the transfer body from turning around the fixing roller, a claw blade or the like that comes into contact with the fixing roller may be provided.

Additionally, a detection element may be provided directly on the roller surface to measure the surface temperature.

As described above, the current state of the heat roller fixing device is that various blades are installed in contact with the fixing roller.

FIG. 1 shows a typical example of a conventional thermo-royal fixing device.

The fixing roller 1, which is in pressure contact with the pressure roller 2, has a heater 4 inside it, and as the transfer body 10 passes between the two rollers, which are adjusted to a certain temperature, the powder adhering to the transfer body 10 is removed. A toner image of the body is fixed onto the transfer body.

Around the fixing roller 1, claws 3 for preventing the transfer body 10 from being wrapped around the fixing roller 1 are pressed so as to peel off the transfer body, and silicone oil is applied by the web 5 positioned so as to be in contact with the fixing roller surface. Silicone oil is applied from reservoir 7 to the roller surface.

The web is pressed against the fixing roller surface by a pressure plate 6.

A temperature detection means 8 is in contact with the fixing roller in order to measure the temperature of the surface of the fixing roller.

The blade 9 is used to scrape off dirt on the roller or excess silicone oil, and is in contact with the fixing roller.

Hereinafter, members that come into contact with the fixing roller, such as claws and web temperature sensing means blades, will be referred to as blades.

In a heat roller fixing device with such a structure,
During copying operations, toner adhering to the fixing roller is deposited on the portions of these blades that come into contact with the roller.

This accumulated toner solidifies as the roller cools when the heat source switch is turned off, and its hardness becomes hard due to the surface coating of the fixing roller.

Therefore, if the fixing roller starts rotating at the same time as the heat source switch is turned ON, there is no room for the solidified toner to soften at the part where the blade etc. contacts the fixing roller, and as a result, the solid toner mass remains on the fixing roller. The coating of the transfer material is damaged, and after long-term use, the damage becomes so severe that the transfer material becomes embossed.

If the roller surface is scratched, toner may stick to the scratches, which poses serious problems in terms of roller durability, roller stains, etc.

The present invention has been made with the object of eliminating the above-mentioned problems in conventional heat roller fixing devices.

That is, the fixing method is characterized in that a required delay time is set to soften or melt the toner stuck to the blade after the heat source of the heat fixing roller is started and before the roller rotates not based on a copying signal. We have devised a heat fixing roller device that can melt toner.

Next, embodiments based on the present invention will be described with reference to the drawings.

In FIG. 2, when the switch SW1 is turned on in conjunction with the power switch (none of which is shown) on the main body of the copying machine, the heater 4
is activated and the fixing roller 1 begins to be warmed, and at the same time, the delay timer T1 begins to operate.

The delay timer T1 is set to seconds for the time it takes for the solidified toner in the contact area between the fixing roller and the blades to melt.

When switch SW1 is connected for seconds, the delay timer T
1, the switch ST1 enters the connected state.

Since the switch SW2 is always connected to form a means circuit on the deceleration means 11 side, the motor 12 is rotated in a deceleration state and the fixing roller is rotated by a transmission means (not shown) so that the temperature of the roller surface becomes uniform. Pre-rotate.

Here, by pressing the copying switch (not shown) on the main body, the switch SW2 is switched to the copying rotation side in conjunction with this, and the motor 12 is rotated at a higher speed (predetermined rotation) than the preliminary rotation, for example, and the copying material is rotated. It is fixed by passing between rollers.

At a certain time after the copying is completed, the switch SW2 returns to the deceleration means 11 side and enters a pre-rotation state.

A similar cycle is repeated depending on the number of copies required using the copy switch.

Even if you turn on the copy switch immediately after turning on the main unit's power switch, this circuit will not work.

In this case, the scheduled time for melting the attached toner may be set to seconds, which corresponds to the so-called warming-up time, but it is also possible to create a protection circuit so that the copying switch is activated only after t seconds or (ten α) seconds have elapsed. Alternatively, a warning display circuit may be provided separately to display a prohibition of turning on the copy switch until (10α) seconds after the delay timer is started.

Switching from pre-rotation to copying rotation in conjunction with the copy switch is effective in improving the durability of the roller fixing device. By configuring a circuit that allows rotation, the life of the heat fixing roller can be significantly extended.

FIG. 3 shows another embodiment in which the temperature of the surface of the fixing roller is detected by a detection means 8 instead of the timer T1 in FIG. A circuit on the deceleration means 11 side is formed, and the motor 12 is rotated in a decelerated state.

The operation of switch SW2 remains as described in FIG.

Here, the combination of the temperature detection means 8 and the specific temperature operation means S1 is activated when the power switch of the main body is turned on (SWl or O
The temperature on the surface of the fixing roller in step N) can be detected by the temperature detection means 8, and the length of the delay time can be automatically set so that the specific temperature operation means S1 can function as a timer switch. When the temperature rises to a point at which the solidified toner on the roller surface melts, the specific temperature operating means S1 may be activated as a switch.

As described above, by setting the delay time and controlling the roller based on the signal from the detection device that detects the initially set temperature of the fixing roller, scratches on the fixing roller caused by solidified toner can be prevented without impairing uniform heating. , a durable roller fixing device can be obtained.

In the embodiment, only one roller has a heater inside, but it is clear that the same effect can be obtained even when the fixing roller and the pressure roller have heaters inside.

[Brief explanation of the drawing]

Figure 1 shows a cross section of a fixing device using an ordinary heat roller;
The figure shows an example (electrical circuit diagram) using a timer, and FIG. 3 shows an example (electrical circuit diagram) using a temperature detection means. 1... Fixing roller, 2... Pressure roller, 3...nail, 4...heater, 5...
...Web, 6...Pressure plate, 7...
Offset prevention liquid reservoir, 8...Temperature detection means, 9
...Blade, 10...Transfer body, 11
... Deceleration means, 12 ... Motor, T1
...Timer, ST1...Timer synchronization switch, SL...Specific temperature activation means.

Claims (1)

[Scope of utility model registration request] A heat roller fixing device including a heat fixing roller having a built-in heat source, a pressure roller provided so as to be able to rotate while being in pressure contact with the roller, and a blade provided so as to be in contact with the surface of the heat fixing roller. After the start of operation, the heat source is turned off using a delay time setting means such as a timer or temperature detection means until the surface temperature of the heat fixing roller reaches a temperature that can melt the toner adhering to the blade. The heat fixing roller is configured to maintain the operating state and to allow rotation of the heat fixing roller based on a signal from the delay time setting means that notifies that the surface temperature of the heat fixing roller has reached a predetermined state. A heat roller fixing device featuring: