JPH0717081Y2 - Image fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an image fixing device, and in particular, an image in which a recording paper is peeled from the heat roller by a separating claw provided along the surface of the heat roller. It is suitable for use in a fixing device.

<Prior Art> An image fixing device has been conventionally used to fix a toner image formed on a recording sheet. In the conventional image fixing apparatus, as shown in the configuration diagram of FIG. 3, the heat roller 1 and the pressure roller 4 are arranged in pressure contact with each other, and the heater 3 is arranged inside the heat roller 1, and 1
By passing the recording paper 5 between the pressure roller 4 and the pressure roller 4, heat and pressure are applied to the recording paper 5 to fix the toner image 6 on the recording paper.

Further, the toner remaining on the surface of the heat roller 1 without being fixed on the recording paper 5 is wiped off by the felt 9, and the recording paper 5 after the fixing is heated by the separation claw 12 arranged along the surface of the heat roller 1. It is peeled from the roller 1.

<Problems to be Solved by the Invention> Since the tip of the separating claw 12 is brought into contact with the surface of the heat roller 1 to separate the recording paper from the surface of the heat roller 1, the recording paper 5 The toner remaining on the surface of the heat roller 1 without being fixed to the toner adheres to the tip of the separation claw 12. Therefore, when the recording paper 5 collides with the tip of the separation claw 12 of the recording paper 5, the toner adhering to the tip of the separation claw stains the recording paper or deteriorates the image quality on the recording paper. There was a problem to do. Further, there is also a problem that the toner attached to the tip of the separation claw 12 damages the coating layer 2 formed on the surface of the heat roller 1 to cause fixing failure.

The present invention has been made in view of the above problems, and an object thereof is to prevent toner from adhering to the tip of the separation claw.

<Means for Solving the Problems> In the image fixing device of the present invention, the recording paper on which the toner image is formed is passed between a heat roller and a pressure roller to apply heat and pressure to the toner image. In an image fixing device that is fixed on the recording paper, and peels the recording paper from the surface of the heat roller by a separating claw provided along the surface of the heat roller, an insulating layer is formed on the surface of the heat roller. At the same time, the separation claw is formed of a conductive member, and a voltage having the same polarity as the charge of the toner image is applied to the separation claw.

<Operation> By providing an insulating coating layer on the surface of the heat roller, the heat roller and the separation claw are insulated. Since the polarity of the voltage applied to the separation claw is the same as the polarity of the charge charged on the toner, the repulsive force of the charge acts between the toner and the separation claw. Therefore, even if the tip of the separation claw is in contact with the surface of the heat roller, the toner remaining on the heat roller does not adhere to the tip of the separation claw. Further, the toner attached to the tip of the separation claw falls off from the separation claw when a voltage is applied.

<Embodiment> FIG. 1 is a block diagram of an image fixing device showing an embodiment of the present invention, and FIG. 2 is an enlarged view of a main part of the image fixing device.

The heat roller 1 has a coating layer 2 made of ethylene tetrafluoride resin (trade name Teflon) formed on the surface thereof, and a heater 3 provided therein. The coating layer 2 makes it difficult for the toner on the recording paper 5 to adhere to the surface of the heat roller 1, and also electrically insulates the heat roller 1 and the separation claw 7. The heater 3 is provided to heat the heat roller 1.
Thereby, the surface of the heat roller 1 is heated to a high temperature of 180 to 200 ° C., for example.

Pressure roller 4 provided in contact with heat roller 1
Is constantly pressed against the heat roller 1 by a spring or the like (not shown). Therefore, when the recording paper 5 is passed between them, heat and pressure are applied to the toner image 6 formed on the recording paper 5, so that the toner image 6 is formed.
Fixed on top.

In this way, the recording paper 5 is brought into close contact with the surface of the heat roller 1 by applying heat and pressure. Therefore,
The separation claw 7 arranged to separate the recording paper 5 from the heat roller 1 is arranged with its tip end in contact with the surface of the heat roller 1. Therefore, if the toner that has not been fixed on the recording paper 5 remains on the surface of the heat roller 1, it adheres to the tip of the separation claw 7 and the above-described inconvenience occurs. In the embodiment, the separating claw 7 is made of a conductive member having excellent heat resistance and wear resistance, and
The voltage of the power supply 8 is applied to the separation claw 7.

The polarity of the voltage applied to the separation claw 7 is selected to be the same as the charge charged on the toner 6a. That is, when the toner image 6 is formed, if the toner is positively charged, a positive voltage is applied to the separation claw 7 as shown in FIG. 1, and if the toner is negatively charged, a negative voltage is applied. Add. By applying a voltage having the same polarity as the electric charge of the toner 6a to the separation claw 7, the toner
A charge repulsive force acts between 6a and the separation claw 7. Therefore, as shown in FIG. 2, the toner 6a remaining on the surface of the heat roller 1 is blown off by the repulsive force and drops before adhering to the tip of the separation claw 7. As a result, in the image fixing device of the embodiment, the tip of the separation claw 7 can be kept clean at all times. Therefore, even if the recording paper 5 collides with the separation claw 7, the toner 6a does not adhere to the recording paper 5. Absent. Further, since the toner 6a does not adhere to the separation claw 7, it is possible to surely prevent the inconvenience of damaging the coating layer 2 by the toner 6a, and it is possible to eliminate deterioration of image quality and improper fixing due to scratches of the coating layer 2. .

The recording paper 5 may be contaminated by the toner 6a dropped by the separation claw 7. Therefore, in order to prevent this, the separation claw 7
The voltage may be applied to the separation claw 7 only while the recording paper 5 does not exist below the. Such on / off control may be performed by a control circuit that controls the drive of the entire apparatus, or a sensor that detects the presence of the recording paper 5 may be provided and the detection output thereof may be used. In this case, the toner 6a adheres to the tip of the separation claw 7 during the period when the voltage is not applied, but since the toner 6a can be dropped when the voltage is applied, the separation claw 7a of the separation claw 7 can be removed. The tip can be regularly cleaned at all times.

<Effect of the Invention> As described above, the present invention applies a voltage having the same polarity as the electric charge of the toner forming the toner image on the recording paper to the separation claw,
Since the repulsive force due to the electric charge of the same polarity acts between the toner and the separation claw, the toner remaining on the surface of the heat roller without being fixed on the recording paper comes into contact with the surface of the heat roller. It is possible to prevent it from adhering to the tip of the separating claw. Therefore, it is possible to prevent the recording paper from getting dirty when it collides with the tip of the separation claw. Further, it is possible to prevent the surface of the heat roller from being scratched by the toner, and the image quality is deteriorated due to the scratch on the surface of the heat roller,
It is possible to prevent fixing failure.

[Brief description of drawings]

FIG. 1 is a block diagram of an essential part of an image fixing device showing an embodiment of the present invention, FIG. 2 is an enlarged view of an essential part of an image fixing device, and FIG. 3 is an essential part of a conventional image fixing device. It is a figure. 1 ... Heat roller, 2 ... Coating layer, 4 ... Pressure roller, 5
… Recording paper, 6… Toner image, 6a… Toner, 7… Separation claw, 8… Power supply

Claims (1)

[Scope of utility model registration request] 1. A recording paper on which a toner image is formed is passed between a heat roller and a pressure roller to apply heat and pressure to fix the toner image on the recording paper, and In an image fixing device in which the recording paper is peeled from the surface of the heat roller by a separating claw provided along the surface, an insulating layer is provided on the surface of the heat roller and the separating claw is formed of a conductive member. An image fixing device, wherein a voltage having the same polarity as the electric charge of the toner image is applied to the separation claw.