JPS5818664A - Heat roller fixing device - Google Patents

Abstract

PURPOSE:To perform adequate fixing operation even if toner is deposited and caked, by detecting the temperature of a fixing roller, and controlling the operations of the fixing roller and a fixing operation assisting means in accordance with the result of comparison with set temperature. CONSTITUTION:With a power switch 29 turned on, an energizing signal from a fixation control means 15 is supplied to input switches 161 and 241 until the surface temperature of a fixing roller 6 obtained by a temperature detector 20 reaches set temperature, and respective solenoids are driven to separate the fixing operation assisting means composed of a peeling pawl 9, a cleaning blade 19, etc., from the roller 6, which turns without any fault. When the surface temperature reaches the set temperature and the toner deposited and caked on the roller 6 is fused and softened, the roller 6 and fixing operation assisting means are controlled to operation states to perform fixation treating operation without any hindrance even if the toner is deposited and caked.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat roller fixing device used in an image forming apparatus such as an electrophotographic apparatus.

Conventionally, a fixing roller and a pressure roller are brought into pressure contact with each other, and both are rotated in opposite directions to pass the recording paper holding the image formed by the pressed toner, and the toner is melted by the heat from the fixing roller. A heat roller fixing device is used to fix the image onto the recording paper. Usually, such a hot-roll prefixing device has a peeling member that separates the fixing roller from the fixing roller during the fixing operation, a cleaning member 5 that removes toner fused to the fixing roller surface, etc., arranged around the surface of the fixing roller. are doing. Such a fixing operation auxiliary means normally operates by contacting the heated surface of the fixing roller. However, when the heat roll fixing device stops and the temperature of the fixing roller decreases, the toner adhering to the fixing operation auxiliary means and also fused to the surface of the fixing roller solidifies.

Therefore, when the heat roller fixing device starts operating again, the hardened toner may scratch the surface of the fixing roller or cause damage to the recording paper. It may be stained with black streaks (or black belts). Furthermore, if the surface of the fixing roller and the peeling member or cleaning member are stuck together due to the toner, they will be damaged. That is, paper jams may occur due to damage to the peeling member. Further, in order to prevent toner from adhering to the surface of the fixing roller, a release agent such as silicone oil is often applied to the surface of the fixing roller. In such a case, if the cleaning member is damaged, the recording paper will become coated with oil, toner will fuse to the surface of the fixing roller, and so-called offset will occur, toner will adhere to the oil application roller and the oil will not be applied to the surface of the fixing roller. This causes the inconvenience of defective products.

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat roller fixing device that can perform an appropriate fixing operation even when toner is fused and solidified.

The heat roller fixing device according to the present invention fixes the toner image on the recording paper by passing the recording paper holding the toner image between the heated fixing roller and the pressure roller that is in pressure contact with the fixing roller. , a means for assisting the fixing operation, which is disposed so as to be able to contact the surface of the fixing roller, and a temperature sensor for detecting the temperature of the fixing roller, and a temperature signal from the temperature sensor and a set temperature signal are detected. The apparatus is configured to perform all operations of the fixing roller and the fixing operation auxiliary means based on the comparison and output operation signals.

According to this invention, when the surface temperature of the fixing roller reaches a set value, the humidity signal output from the temperature sensor is used to perform all operations of the fixing roller and the fixing operation auxiliary means,
This allows the toner image to be fixed on the recording paper. Therefore, at the time when the fixing roller or the fixing operation auxiliary means is all activated, the toner is heated to the set temperature, and it is possible to prevent damage to the fixing roller or the fixing operation auxiliary means due to toner solidification. I can do it.

It is also possible to prevent stains on the surface of the recording paper, which conventionally occur due to such damage.

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

FIG. 1 shows a heat roller fixing device 1 as an embodiment of this invention. This heat roller fixing device 1 is installed in an electrophotographic apparatus (not shown), and includes a fixing roller 2 and a pressure roller 5 that is pressed against the fixing roller 2 with a predetermined pressure by a spring or the like (not shown).

The fixing roller 2 is rotationally driven by the drive device 4, so that the pressure roller 5? The fixing roller also follows the fixing roller and rotates in the opposite direction. A heater 5 is disposed within the fixing roller 2, and the fixing roller 2, which is made of a material with good thermal conductivity such as metal, is heated by the heater 5. This heater 5 is supplied with a current controlled by a heater control circuit (not shown), and is configured to maintain the temperature of the surface 6 of the fixing roller 2 at a predetermined value. A transport path 8 through which the recording paper 7 passes from below to above is arranged between the fixing roller 2 that rotates in the direction of the arrow a and the pressure roller 5 that comes into pressure contact with the fixing roller 2 from the side. The recording paper 7 that has passed through both rollers 2.5 usually tends to adhere to the fixing roller 2 side, and the surface 6 of the fixing roller is near the position facing the conveying path 8 of the fixing roller 2.
A peeling claw 9 for separating the recording paper 7 is provided. A guide plate 1 is located at a position facing this peeling claw 9 via the conveyance path 8.
0 is attached, and the recording paper 7 separated from the fixing roller 2 by this and the peeling claw 9 is moved along the conveyance path 81C. This peeling claw 9 is a guide groove 1 in which the substrate NIC is formed.
2 - support rod 1 on a sliding plate 15 capable of sliding a fixed amount;
4 (see Figure 2). This sliding plate 15 is operated by a solenoid 16 that operates to retract when it receives an activation signal I4 from a fixing operation control circuit 15, which will be described later, and a barb 17 that applies a pulling force in the opposite direction. That is, when the solenoid 16 is activated by the activation signals t and K,
The sliding plate 15 is moved away from the fixing roller 2 side against the tensile force of the tension spring 17. In this case, the claw portion 901 of the peeling claw 9 on the sliding plate 15 is rotated slightly clockwise by the tension bar 18 hooked between the protrusion 902 of the peeling claw 9 and the sliding plate 15, and It operates to separate from the surface 6 of the fixing roller.

On the other hand, when the solenoid 16 is not energized, the sliding plate 13 is pulled down toward the fixing roller 2 by the tension spring 17, and the claw portion 901 of the peeling claw is pressed against the surface 6 of the fixing roller by the elastic force of the tension spring 18. Then, the recording paper 7 can be separated.

Around the fixing roller 2, a peeling claw 9IL, followed by a cleaning blade 19, a temperature sensor 20, and an oil applicator 21 are arranged facing each other in this order.

As shown in FIG. 3, the cleaning blade 19 is pressed against the surface 6 of the fixing roller by the force of a tension spring 22 to clean the surface 6. One end of the support rod 25 of the cleaning blade 19 is slidably fitted into a guide groove Q formed on the substrate 11, and is pulled downward by a tension spring 22, and when the solenoid 24 is energized, it is moved upward, that is, fixed. He is pulled up away from the rollers. Therefore, when the solenoid 24 receives an activation signal 11 from a fixing operation control circuit 15 to be described later and is activated, the cleaning blade 19 is separated from the surface 6 of the fixing roller. When the solenoid 24 does not receive the actuation signal 11-, the cleaning blade 19 is pressed against the surface 6 of the fuser roller by the tension spring 22 to perform the cleaning operation.

The oil applicator 21 is disposed below the fixing roller 2, and the oil applicator 21 is in contact with the silicone oil supply roller 211 housed in the oil tank 25.
12 is used to uniformly coat the surface 6 of the fixing roller to prevent the toner T from fusing to the surface 6.

Temperature sensor 20 brings a temperature sensitive element, such as a thermistor, into contact with the surface 6 of the fuser roller. And this temperature sensor 2
0, the signal S1 corresponding to the temperature of the surface 6 is compared with the signal corresponding to the toner melting temperature as the set temperature, and the surface 6 outputs the operation signal 11 during the time period when the toner melting temperature is not reached. The fixing operation control circuit 1 lowers the output at the time when
Connected to 5.

The fixing operation control circuit 15 includes a well-known comparison circuit 26 and a well-known driver 261 that receives a signal from the comparison circuit 26 and sends out an operation signal 11f. The fixing operation control circuit 15 is connected to the input switches 161 and 241 of the solenoid 16 that operates the peeling claw 9 and the solenoid 24 that operates the cleaning blade 19, and these input switches 161 and 241 are connected to the operation signal I,
It turns on when received.

A drive device 4 that rotates the fixing roller 2 includes a roller side gear 27 that is integrally connected to the fixing roller 2, and a reduction gear train 2 that drives the roller side gear 27 and receives driving force from a drive source M.
It consists of 8. This drive source M receives current supply and starts operating when a power switch 290 of an electrophotographic apparatus (not shown) is turned on.

Operation of the heat roller fixing device 1 shown in FIG. 1? explain.

First, when the power switch 29 is turned on, the temperature sensor 20 measures the temperature of the surface 6 of the fixing roller, and the fixing operation control circuit 15 detects that the toner melting temperature has not been reached. , sends an energizing signal 11 to each input switch +61.241.

As a result, each solenoid 16.24 is energized, and the peeling claw 9 and cleaning blade 1 serve as fixing operation assisting means.
9 operates to separate from the surface 6 of the fixing roller.

Therefore, even if the drive device 4 operates and the fixing roller 2 rotates, the peeling claw 9 and the cleaning blade 19 do not come into contact with it, and no operation is performed to assist in fixing. The non-operating state of the fixing operation assisting means is detected by an electrophotographic control circuit (not shown), a warming-up state is displayed, and the fixing operation is on standby. When the surface 6 of the fixing roller reaches the toner melting temperature, the fixing operation control circuit 15 switches the output to a low level, so each switch 161, 241 is turned off, and each solenoid 16
．． 24 is deenergized. Then, the peeling claw 9 is drawn toward the fixing roller 2 by the tension spring +7VC, and is pressed onto the surface 6 by the elastic force of the tension spring 18, and the recording paper 7
The cleaning blade 19 is pressed against the surface 6 of the fixing roller by the tension spring 22, and the cleaning blade 19 is pressed against the surface 6 of the fixing roller.
Start cleaning. At this time, the toner T on the surface of the peeling claw 9, cleaning blade 19, and fixing roller is softened by coming into contact with the surface 6 of the toner melting humidity, and no damage is caused to each member.

The heat roll fixing device 1 shown in FIG.
The temperature sensor 2o operates at the same time as the 0-on operation, and the fixing roller 2 o is activated to separate the peeling claw 9 and the cleaning blade 19 from the surface 6 of the fixing roller that is about to start rotating.
Even when the toner T rotates, it is possible to prevent the solidified toner T from being damaged due to adhesion between each member, to prevent jamming caused by damage to the peeling claw 9 as in the conventional case, and to prevent damage to the cleaning blade 19 due to damage. It is possible to prevent the occurrence of black streaks and oil stains on the paper surface 7.

The heat roller fixing device 1 shown in FIG. 1 is equipped with a peeling claw 9 and a cleaning blade 191 as fixing operation auxiliary means, and these are supported so as to be able to come into contact with and separate from the surface 6 of the fixing roller. The means are not limited to these, but may be other means that come into contact with the surface 6 and perform an operation that accompanies or assists the fixing operation.

The heat roller fixing device 1 shown in FIG. 1 rotates the fusing aperture roller 2 in conjunction with the ON operation of the power switch 290, and moves the peeling claw 9 and cleaning blade 19 into an operating position and a non-operating position. I was doing a moving operation.

On the other hand, peeling claw 9 spear 9 - Jung blade 1? A thermal roller fixing device 50 in a constantly operating position, that is, in contact with the surface 6 of the fixing roller, and in which the rotation of the fixing roller 2 is controlled by an operating signal I2, will be described with reference to FIG.

Since this heat roller fixing device 50 includes the same members as the heat roller fixing device 1 shown in FIG. 1, the same members are given the same reference numerals and the same explanations will be omitted. Around the fixing roller 2, a peeling claw 51, a cleaning blade 52, a temperature sensor 20, and an oil applicator 21 are arranged facing each other in this order from a position facing the upper conveyance path 8. The peeling claw 51 and the cleaning blade 52 are both pressed into contact with the surface 6 of the fixing roller, and are attached so that their engagement positions cannot be changed. on the other hand,
The fixing roller 2 is rotated by a driving device 55 as shown in FIG. This drive bag @55 includes a roller side gear 27 that is integrally connected to the fixing roller 2, a drive gear 54 that meshes with this, and a gear 5 that inputs the driving force from the drive source M.
5, and an electromagnetic spring clutch 56 received by the clutch 5. An input switch 562 that receives an actuation signal I2 from the fixing operation control circuit 57 is connected to a control coil 561 that controls the driving force of the electromagnetic spring clutch 56 on and off. This fixing operation control circuit 57 includes a well-known comparator circuit 58 and a well-known driver 581 which receives a signal from the comparator circuit 58 and sends out an operation signal, in the same way as explained in the above-mentioned fixing operation control circuit 15. As a result, the temperature signal S from the temperature sensor 20 and the signal corresponding to the Yanner melting temperature?
In comparison, the output is held at a low level during the time period when the surface 6 does not reach the toner melting temperature, and when the temperature reaches the toner melting temperature, the output is sent to the activation signal switch 562 as an output. Therefore, when the input switch 562 is turned on in response to the operation signal l2fi-, the rotational force of the input gear 55 is transmitted to the drive gear 54, whereby the roller side gear 27 rotates and the fixing roller 2 is rotated. On the other hand, when the input switch 562 is in the OFF state, the rotational force from the drive source M is not transmitted to the fixing roller 2 side because the input gear 55 idles.

The heat roller fixing device 50 shown in FIG.
The drive source Mi is driven by the 90 ON operation.

At this time, the fixing operation control circuit 57 maintains the output at a low level because the temperature sensor 20 does not detect the toner melting temperature at first. Therefore, the input switch 562 remains off, the electromagnetic spring clutch 56 does not operate, the input gear 55 continues to idle, and the fixing roller 2 does not rotate. In such a warming-up state of the fixing roller 2, the fixing operation is on standby. When the surface 6 of the fixing roller reaches the toner melting temperature, the fixing operation control circuit zI7 outputs an operation signal as an output, the electromagnetic spring clutch 56 is activated, and the input gear 550 rotations are transferred to the drive gear 4.
and rotates the fixing roller 2. At this point, the surface 6 of the fixing roller and the peeling claw 51. The toner T adhering to the cleaning blade 52 is melted and will not be damaged by the toner even when the various members operate.

The heat roller fixing device 5o shown in FIG. 4 also has the same effect as the heat roller fixing device 1 shown in FIG.

In the above-mentioned place, the temperature signal S1 from the temperature sensor 2o
The set point temperature signal is compared to the toner melt temperature signal n
*However, it is not limited to this, and if necessary, it may be set higher or lower as long as it does not damage each member.

Furthermore, although the fixing roller 2 shown in FIGS. 1 and 4 is equipped with a heater 5 inside, the fixing roller 2 may be configured to be heated by a heating roller (not shown) having a built-in heater, depending on the case. . In this case, it is desirable that the cleaning blade 19 as a fixing auxiliary means be attached to the heating roller side.

As mentioned above, if the heat roller fixing device to which this invention is applied is used, a toner image will be formed on the recording paper. Can be fixed accurately and without stains.

[Brief explanation of drawings]

1 and 4 are schematic side views showing different embodiments of the present invention, FIG. 2 is an enlarged side view of the peeling claw shown in FIG. 1, and FIG. 5 is a cleaning blade shown in FIG. 1. FIG. 5 is a sectional view of essential parts of the drive device shown in FIG. 4. 1.50... Heat roll fixing device, 2... Fixing roller, 5... Pressure roller, 6... Surface 1.7... Recording paper, 9... Peeling claw, 19...・Cleaning blade, 20... Temperature detector, 26... Fixing operation circuit, 1
1... energizing signal, X2... operating signal, SL... temperature signal, T... toner.

Claims (1)

[Scope of Claims] t. A recording paper holding an image made of toner is passed between a heated fixing roller and a pressure roller that is in pressure contact with the fixing roller, thereby fixing the toner image on the recording paper. The apparatus is provided with a means for assisting the fixing operation, which is disposed so as to be able to contact the surface of the fixing roller, and a temperature sensor for detecting the temperature of the fixing roller, With a signal. A heat roller fixing device configured to cause all of the fixing roller and fixing operation auxiliary means to be operated in response to an operation signal outputted by comparing the temperature signal with a set temperature signal. 2. The heat roller fixing device according to claim 1, wherein the set temperature signal is a toner melting temperature signal. The motion assistance means received an activation signal. The heat roller fixing device according to claim 1 or 2, wherein the heat roller fixing device moves to a position where it comes into contact with the surface of the fixing roller and operates. 4. The fixing operation auxiliary means is always in contact with the surface of the fixing roller, and the fixing roller operates when receiving an operation signal. Heat roller fixing device.