JPS631324Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device for a copying machine, and more particularly to an improvement in a device that detects the amount of anti-offset liquid applied to a fixing roller and applies the anti-offset liquid.

Conventionally, when fixing an unfixed toner image with a roller, such as a heat roller or a pressure fixing metal roller, it is possible to prevent the toner from adhering to the roller and staining the copy surface with this toner (hereinafter referred to as the offset phenomenon). To do this, the rollers are coated with silicone liquid. This application method includes impregnating felt with silicone liquid and pressing it against a roller, or immersing a part of the cloth in a bath of silicone liquid and bringing the other end into contact with the roller. is used. However, it is difficult to control the amount of silicon impregnated into the felt, and excessive silicon may adhere to the roller.
The copy surface was sometimes stained with liquid. In addition, the amount of silicon applied in the past is always pressed against the roller,
This encouraged the tendency to use too much silicon.
To improve this, the applicator is made movable, and when not copying, the applicator is separated from the roller.
Some are designed to come into pressure contact with the roller only when copying. However, even this method results in an oversupply of silicon. In other words, this silicon coating device faces the contradictory problem of how to supply the minimum necessary amount of silicone liquid stably and over a long period of time. Therefore, in the case of heat roller devices that use a metal roller coated with silicone rubber, offset is prevented by the silicone itself impregnated into the silicone rubber of the heat roller without applying this silicone liquid from the beginning. There are some things. However, the silicone rubber of the heat roller itself is generally thin, several millimeters thick, in order to increase heat transfer efficiency, and there is a limit to the amount of silicone that can be impregnated into the silicone rubber itself. Furthermore, since a high temperature heater is contained inside this heat roller, the disappearance of silicon is further promoted. Furthermore, even when the impregnated silicone has run out, it may be unreasonable that the mechanical life of the roller has not yet been reached. Therefore, it has become an important issue to apply an appropriate amount of anti-offset liquid not only to avoid staining the copying surface, but also to extend the life of the heat roller device.

The present invention was devised in view of the above-mentioned conventional drawbacks, and is designed to appropriately control the amount of silicone liquid applied by detecting the amount of silicone liquid applied to the roller.

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

FIG. 1 is a sectional view showing one embodiment of the present invention. 1 in the figure, a toner image is formed on the top surface,
Copy sheets 2 and 3 sent to the fixing section are made of a pair of heater lamps 6 and 7 arranged in hollow cylinders 4 and 5, respectively, and silicone rubber 8 and 9 coated on the surface of the hollow cylinders. This is a heat roller, and this roller constitutes a fixing section. One of the heat rollers 2 is provided with a coating material 10 impregnated with an anti-offset liquid to face the roller surface (silicone rubber 8) in order to apply an anti-offset liquid (generally silicone liquid or the like). This coating material 10 is attached to a holding member 11. Further, the holding member 11 is rotatably supported by a pin 12 at one end, and a spring 13 is biased at the other end.
is provided. Therefore, since the holding member 11 is normally rotated clockwise by the biasing force of the spring 13, the coating material 10 is separated from the heat roller 2. The solenoid 14 is controlled by a signal from the control circuit 15, whereby the coating material 10 comes into opposing contact with the heat roller 2.

On the other hand, reference numeral 16 is a friction roller for detecting the amount of applied anti-offset liquid, which is the main purpose of the present invention. The friction roller 16 is provided so as to lightly contact the surface of the upper heat roller 2. Details of the friction roller 16 are shown in FIG. In the figure, the friction roller 16 has its shaft 16a mounted on both frame plates 16b, 16c.
It is rotatably held via d and 16e,
A disk 17 is fixed to one end of the shaft 16a. A notch 18 is provided on the outer periphery of the disc 17 as shown in FIG. Further, the light emitting element 1 is placed between the disc 17 and facing the notch 18 of the disc.
9 and a light receiving element 20 are provided. A disc 1 having the light emitting element 19, the light receiving element 20, and the notch 18
7, the number of rotations of the friction roller 16 is detected, and the light reception signal of the light receiving element 20 is sent to the counter circuit 21.
has been entered. Therefore, the counter circuit 21 detects the number of rotations of the friction roller 16 per predetermined time. Further, the counter circuit 21 is connected to the solenoid control circuit 15, and outputs a control signal according to a change in the rotation speed of the friction roller 16. In addition, 22 in the figure is a brake for the coating amount detection roller 16.

In the apparatus configured as described above, the friction roller 16 for detecting the amount of applied offset liquid is in light contact with the heat roller 2. An appropriate braking force is applied to the roller 16 by a brake 22. In this state, heat roller 2
When the silicone liquid is applied on the detection roller 16, no frictional force acts on the detection roller 16, and the roller 16 does not rotate, or the number of rotations thereof is very low.
In this state, not much signal from the light receiving element 20 is input to the counter circuit 21, and since the rotation speed of the friction roller 16 is below the specified rotation speed, the counter circuit 21 does not output a control signal. In other words, the solenoid 14 is not energized and the anti-offset liquid coating material 10 is separated from the heat roller 2.

By the way, when the silicone liquid on the surface of the heat roller 2 decreases, frictional force acts on the friction roller 16, and the friction roller 16
It will rotate at approximately the same speed as the circumferential speed of. In this state, when the rotation speed of the friction roller 16 becomes high and exceeds the specified rotation speed A, the counter circuit 2
1 outputs a signal to the control circuit 15. As a result, the solenoid 14 is energized, so that the coating material 10 is pressed against the heat roller 2. In other words,
When the friction roller 16 reaches the rotation speed A, the coating material 10 comes into contact with the heat roller 2, and the anti-offset liquid is applied. Due to this action, when the anti-offset liquid is applied to the entire circumferential surface of the heat roller 2, the frictional force between the friction roller 16 and the heat roller 2 decreases, and the rotational speed of the friction roller 16 decreases. Here, the rotational speed of the friction roller 16 does not immediately decrease when the coating material 10 comes into contact with the heat roller 2, but instead, the offset prevention liquid becomes familiar with the entire circumferential surface of the heat roller 2 and the circumferential surface of the friction roller 16. In this state, the rotation speed of the friction roller 16 gradually decreases.

Then, the rotation speed of the friction roller 16 decreases,
When the rotational speed becomes below A and further reaches B, the energization to the solenoid 14 is released, the coating material 10 is separated from the heat roller 2, and the coating of the offset prevention liquid is completed. Even when the rotational speed of the friction roller 16 reaches B and the coating material 10 separates from the heat roller 2, the rotational speed of the friction roller 16 does not immediately increase, and due to a delay in response, the rotational speed temporarily drops below B. From this state, the number of rotations gradually increases in response to the offset prevention liquid on the two surfaces of the heat roller gradually disappearing.
However, once the offset prevention liquid is applied,
The rotation speed of the friction roller 16 does not increase rapidly until this liquid runs out.

Note that the rotation speed of the friction roller 16 is set at a predetermined time,
That is, since the counting is performed over a relatively long period of time, for example, 10 seconds to 30 seconds, malfunctions due to temporary fluctuations in the rotation of the friction roller 16 can be prevented.

As described above, according to the anti-offset liquid application device of the present invention, if the rotation speed of the friction roller rotatably provided in sliding contact with the fixing roller exceeds the specified rotation speed A, the above-mentioned fixing by the anti-offset liquid application means is performed. When the application to the roller is started and the rotation speed falls below the specified rotation speed B (A>B), the application to the fixing roller by the application means is terminated, so the rotation of the friction roller is temporary. It is possible to supply the anti-offset liquid before the fixing roller is contaminated with toner, etc. without malfunctioning, and also to prevent excessive application of the anti-offset liquid, allowing for more appropriate application control of the anti-offset liquid. It becomes possible.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention. FIG. 1 is a sectional view of the fixing section, FIG. 2 is a structural diagram for explaining details of the friction roller, and FIG. 3 is a sectional view of the fixing section. FIG. 3 is a plan view of a disk fixed to the shaft of the friction roller in FIG. 2; 1... copy paper, 2... heat roller, 10...
...Offset prevention liquid coating material, 15...Control circuit,
16... Friction roller, 17... Disc, 19... Light emitting element, 20... Light receiving element, 21... Counter circuit.

Claims (1)

[Scope of utility model registration request] A fixing roller passes a sheet of paper with an unfixed toner image between the rollers and fixes the toner image.
a coating means for applying an anti-offset liquid to the fixing roller; a friction roller rotatably held in opposition to the fixing roller; a detection means for detecting the number of rotations of the friction roller; a starting means for starting coating on the fixing roller by the applying means when the detected number of rotations per predetermined time is equal to or greater than a specified number A; and Rotation speed B
1. An anti-offset liquid coating device for a copying machine, comprising: a termination means for terminating the coating on the fixing roller by the coating means at the following times.