JP2507981Y2 - Fixing device for electrophotographic device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic apparatus such as a copying machine, a facsimile, and a printer. In particular, an electrophotographic apparatus that has at least two fixing rollers that rotate in contact with each other and that fixes the toner image on the material while the material carrying the toner image is conveyed through the contact portion of the fixing roller. The present invention relates to a fixing device of an apparatus.

2. Description of the Related Art Generally, in an electrophotographic apparatus, while a material such as transfer paper is conveyed through the apparatus, a toner image transfer process and a toner image fixing process are performed on the material. The material conveyed in the apparatus may be skewed (bent) for the following reasons.

The material conveying path in the electrophotographic apparatus may have a curved shape instead of a straight shape. In such a curved conveyance path, the conveyance resistances of both sides of the material are likely to differ. When the lumber is weak, skew occurs when the conveyance resistances on both sides of the lumber are different as described above.

Materials conveyed in the electrophotographic apparatus are charged due to the influence of friction and the like. When the material is electrified, an electrostatic attraction force is generated between the material and a guide plate forming the material conveying path, and this becomes the material conveying resistance. In general, the charge amount of the material is not uniform in the width direction of the material (direction perpendicular to the material conveying direction), so that the above-mentioned conveyance resistance also differs, resulting in skew.

If the parts of the conveying roller and the guide plate forming the material conveying path are poor in accuracy or their assembling accuracy is poor, the conveying resistance to the material is not uniform and skew occurs.

By the way, an electrophotographic apparatus has a photoconductor on which a toner image is formed and two fixing rollers that are in contact with each other, and transfers the toner image on the photoconductor onto the material while the material passes through the photoconductor. However, there is a work in which the toner image on the material is fixed on the material while the material after the transfer passes through the contact portion between the fixing rollers.

In the electrophotographic apparatus of this type, when the above-mentioned transfer and fixing work is performed using a long-length material, while the part of the material is still passing through the photoconductor, the other part of the material is a fixing roller. A situation occurs in which the roller reaches the contact portion and is sandwiched by both rollers.

In such a case, if the above-mentioned skew occurs in the material entering the fixing roller, the material is displaced laterally with respect to the transport direction while the material is transported between the fixing rollers. For example, as shown in FIG. 14, the material P is in the original transport direction F (direction substantially orthogonal to the axial direction 1 of the fixing roller R).
When it is conveyed in the Q direction while being inclined by the angle θ, the fixing material R shifts the material P in the arrow S direction.

In the electrophotographic apparatus currently under consideration, as described above, the material P
However, even in the state of being sandwiched between the fixing rollers R, a part of the material is still passing through the photoconductor. In this case, if the material moves in the S direction in FIG. 14, the following problems will occur. First, the toner image transferred onto the material is transferred from a place where it should originally be transferred, and the transferred image is bent. Further, since the material between the photoconductor and the fixing roller is twisted, there are places where the photoconductor and the material do not sufficiently adhere. Since transfer is not performed well at this place, so-called white voids in the image occur. Further, the twisted material is pushed by the fixing roller as described above, so that the material is wrinkled.

Due to the possible problems as described above, conventionally, when the above-mentioned transfer and fixing are performed using a long material such as roll paper, so-called atmosphere fixing or flash fixing without using a fixing roller in the fixing unit. And so on.
However, quick fixing processing cannot be performed by these fixing methods.

Problems to be Solved by the Invention The present invention, even when using a long material,
An object of the present invention is to make it possible to perform a fixing operation by using a roller, and to execute a rapid fixing process, and thus a high-speed electrophotographic process.

Another object of the present invention is to correct skew of materials generated in the electrophotographic apparatus in the fixing device.

Means for Solving the Problems According to the present invention, the fixing device has the following configuration,
That is, a material deviation detecting means for detecting that the material is displaced laterally with respect to the material conveying direction, and a roller for moving at least one of the at least two rollers laterally with respect to the material conveying direction. By having a moving means and a control means for driving the roller moving means so as to move the at least one roller in a direction opposite to the material deviation direction in accordance with the material deviation detected by the material deviation detection means. Will be resolved.

In the above configuration, the material is a material that is sent to the fixing device with an unfixed toner image placed thereon. Various materials such as paper materials and plastic sheet materials can be considered. In an electrophotographic apparatus, this material is sometimes called a transfer material because a toner image is transferred onto this material by so-called transfer processing.

The material deviation detecting means detects whether the material to be conveyed moves in the left or right direction with respect to the conveyance direction. Although this is not limited to a special configuration, for example, a configuration in which material detection means such as a light-reflective sensor is provided slightly outside the left and right sides of the material conveyed in the normal state, respectively. Can be adopted. If the material is skewed in either the left or right direction, the material is detected by any of the material detecting means.

The roller moving means is not limited to the special configuration either. In short, at least one roller is moved in the lateral direction with respect to the material conveying direction, that is, in any of the left and right directions. Only one of the pair of rollers may be moved, or both rollers may be simultaneously moved in the same direction.

The material conveyed in the electrophotographic apparatus is skewed for some reason. Generally, in an electrophotographic apparatus, when the material of the material is uneven, the skew direction of the material tends to be determined. When the material coming into the fixing roller pair has a skew, in the present invention, the material material displacement detection means detects the material material displacement direction, and at least one roller moves in a direction opposite to the material material displacement direction. . As the roller moves, the material is forcibly moved in the direction opposite to the shift direction. As a result, the skew of the material is corrected.

Embodiment 1 FIG. 1 is an overall side view of an electrophotographic apparatus according to an embodiment. In the figure, a charging charger 30, a laser exposure device 32, and a developing device are provided around a photosensitive member 17 formed in a drum shape.
20, a transfer charger 25, a separation charger 31, and a cleaning device 33 are provided. The photoconductor 17 rotates counterclockwise, and is first charged uniformly by the charging charger 30 in the axial direction (direction perpendicular to the paper surface).

A laser diode (not shown) is provided in the laser exposure device 32.
Is built in. Laser light is output from this laser diode based on an externally binarized image signal. The output laser light is reflected by the rotary polygon mirror 11. The left side of the rotary polygon mirror 11 is used to correct the cross-sectional shape of the laser light into an accurate circle, and to correct the optical path of the reflected light when the rotary polygon mirror 11 is tilted from the normal state.
Cylindrical lenses 12 are arranged. Further, on the further left side, an f-θ lens 13 is arranged for focus correction and laser light scanning speed correction. The laser light reflected by the rotary polygon mirror 11 is cylindrical lens 12 and f.
After passing through the -θ lens 13, the first mirror M1, the second mirror M2,
Then, after being reflected by the third mirror M3, it is guided to the photoconductor 17. As a result, an electrostatic latent image corresponding to the image signal is formed on the photoconductor 17.

The electrostatic latent image formed on the photoconductor 17 is then developed by the developing device.
20 is developed into a visible toner image.

Three rolls of paper at the lower left of the electrophotographic device
21a, 21b, 21c are arranged. Any one of these roll papers is selected and fed toward the photoconductor 17. The roll paper is conveyed to the photoconductor 17 by the register roller 24 at such a timing as to overlap the toner image on the photoconductor 17. A transfer charger 25 is provided at a transfer position where the roll paper and the toner image overlap with each other, and the toner image on the photoconductor 17 is transferred onto the roll paper by the discharge of the transfer charger 25.

After that, the roll paper is peeled from the photoconductor 17 by the discharge of the separation charger 31 and the action of a separation claw (not shown). The peeled roll paper is transported to the fixing device 26 by the transport belt 29, undergoes a fixing process by the fixing device, and is then discharged onto the paper discharge tray 27 at the top of the device.

The roll paper 21a, 21b or 21c is sent out by the sending roller 22 and then cut by the cutter 23 at a proper timing to form one sheet. When the sheet paper produced by cutting is long, a situation occurs in which the transfer process is still being performed on the photoconductor 17 when the fixing process is performed by the fixing device 26.

As described above, in many electrophotographic apparatuses, skew may occur in the roll paper (or sheet paper) being conveyed due to the peculiar properties of the apparatus. In this embodiment, the fixing device 26 is formed as a so-called roller type fixing device having the two fixing rollers 1 and 3, so that the roll paper entering the fixing device 26 is skewed. Then, when this is sandwiched by both rollers 1 and 3 and conveyed, the roll paper is displaced as shown in FIG. If such a deviation occurs, wrinkles may occur on the roll paper, or a toner image transfer failure may occur. In order to avoid such a problem, the fixing device 26 can be configured as follows.

In FIG. 2, the upper roller 1 in the fixing device 26 is
Has a heat-resistant release layer on the surface of a metallic cylindrical core,
Further, a heater 2 is provided inside thereof. The roller 1 is heated to a predetermined temperature, for example, about 185 ° C. by this heater. Hereinafter, the roller 1 is referred to as a heating roller. The other roller 3 has a heat resistant elastic body on the surface of a metal cored bar, and is elastically pressed toward the heating roller 1 by the pressure levers 14 and 15 and the springs 9 and 10. Hereinafter, the roller 3 is referred to as a pressure roller.

As shown in FIG. 3, the fixing device 26 has two side plates 4 and 5 located on both sides of the roll paper in the transport direction Q. In FIG. 2, only one side plate 4 is shown. The heating roller 1 is driven by a drive source (not shown) to rotate in a counterclockwise direction, but is supported by the side plates 4 and 5 so as not to change its position. As shown in FIG. 4, the pressure roller 3 has its shaft end supported by pressure levers 14 and 15. The pressure levers 14 and 15 are both side plates 4
And 5 are rotatably mounted by pins 16 and 18. A columnar connecting member 6 is provided between the pressure levers 14 and 15. Connecting member 6 and both pressure levers 14,
The 15 connecting parts are such that they can rotate freely relative to each other.

In FIG. 2, a rotary shaft 19 is provided on the left side of the pressure lever 14. The rotary shaft 19 is rotatably supported by the side plates 4 and 5. As shown in FIG. 4, a protrusion 7 is fixed on the rotary shaft 19 at a position facing the pressure lever 14, and another protrusion 8 is fixed at a position facing the pressure lever 15. As shown in FIG. 2, the protruding directions of the projecting piece 7 and the projecting piece 8 are offset from each other by approximately 180 °. As shown in FIG. 4, tension springs 9 and 10 are attached between the projecting ends of the projecting pieces 7 and 8 and the pressure levers 14 and 15, respectively.

A knob (not shown) is fixed to the rotary shaft 19,
The operator can turn it to the right and left by an appropriate angle, for example, about 45 °. When the rotary shaft 19 is in the neutral position, the projecting piece 7 is in the upper position and the projecting piece 8 is in the lower position as shown in FIGS. 5 and 2. At this time, the springs 9 and 10 pull both pressure levers 14 and 15 with equal spring force. Therefore, the pressure roller 3 has the shaft end 3a and
A force equal to 3b is applied and pressed against the heating roller 1.

When the rotating shaft 19 is rotated counterclockwise in FIG. 2 by the operator, the projecting piece 7 is moved to the left position, as shown in FIG.
Then, the projecting piece 8 moves to the right position. This allows the shaft end 3a
The side spring 9 is pulled to increase the pressure of the pressure roller 3 on the shaft end 3a side, while the spring 10 on the shaft end 3b side is contracted to weaken the pressure on the shaft end 3b side. When the rotary shaft 19 is rotated clockwise by the operator in FIG. 2, the projecting piece 7 moves to the right position and the projecting piece 8 moves to the left position as shown in FIG.
As a result, the pressure on the shaft end 3b side of the pressure roller 3 is strong, while the pressure on the shaft end 3a side is weak.

In FIG. 4, a bracket 31 is rotatably attached to the connecting member 6 at a substantially central portion thereof by a pin 28. The bracket 31 has a certain length in the axial direction of the pressure roller 3, and a plurality (for example, 6) of tension springs 34 are attached side by side in the axial direction. The other ends of these springs 34 are hooked on a substrate 35 fixed between both side plates 4 and 5 (side plate 5 is not shown), as shown in FIG. With the above-mentioned configuration regarding the spring 34,
Equal pressure is applied to both shaft ends 3a and 3b of the pressure roller 3.

The operation of the fixing device having the above structure will be described below.

In this embodiment, as shown in FIG. 1, three types of roll papers 21a, 21b, 21c are used. These rolls have their own skew within the electrophotographic apparatus depending on their individual properties. For example, the top paper 21a tends to skew toward the roll shaft end 3b in FIG. 4, and the center paper 21b and the bottom paper 21c tend to skew toward the roll shaft end 3a in FIG. Is.

When the operator selects any one roll paper, the operator rotates the rotary shaft 19 in either the left or right direction so that the pressure at the roll end portion in the direction opposite to the direction in which the roll paper will be skewed becomes stronger. .

Generally, as shown in FIG. 8, the paper P has a pair of rollers R1.
Assuming that the roller pressing force on the A side is greater than the roller pressing force on the B side when passing between R and R2, the conveyance speed vector of the paper becomes larger on the A side as shown in the figure. The reason is that the friction coefficient between the roller and the paper is μ, and the roller pressure is T
Then, the force F that the rollers R1 and R2 try to convey the paper P becomes F = μT, and the larger the T, the larger the F becomes, and the contact width (nip width) between the rollers becomes different due to the difference in the pressing force. This is because the peripheral speed changes. When the conveyance speed on the A side increases, the paper P first begins to tilt as indicated by the broken line, and when the paper is conveyed in that tilted state, the entire paper then shifts to the A side as indicated by the alternate long and short dash line.

Since the heating roller 1 and the pressure roller 3 are a pair of rollers that are in contact with each other, they have the above-described paper conveyance characteristics. Therefore, if the pressure of the roller end portion in the direction opposite to the paper skew direction is increased by the operator, the skew of the roll paper entering between the rollers 1 and 3 can be corrected.

The above is the description of the case where the pressure adjustment between the rollers 1 and 3 is manually performed. In addition to this, the pressure can be automatically adjusted as follows.

When performing such automatic adjustment, first, the skew of the roll paper is detected. For example, as shown in FIG.
Paper detection sensors 36 and 37 such as reflection type optical sensors are provided on both sides of the normally conveyed roll paper P. Both of the paper detection sensors 36 and 37 are in the OFF state when the paper is conveyed normally, that is, without being skewed. When the paper skews to one of the directions as indicated by the arrow, the paper detection sensor for the misaligned paper is turned on, and the skew of the paper is detected. The paper detection signal of the paper detection sensor is sent to the CPU (not shown).

When performing automatic adjustment, a rotary drive means (not shown) such as a stepping motor is attached to the rotary shaft 19 shown in FIG. 4 in place of a knob for manual operation. The rotation driving means is driven by the CPU that detects the skew of the paper by the signal from the paper detection sensor, and the roller pressure in the direction opposite to the skew direction is increased. As a result, the skew of the paper is automatically corrected.

FIG. 9 is a side sectional view of an embodiment of the present invention. The fixing device 26 is used in place of the fixing device shown in FIG. 2 in the electrophotographic apparatus shown in FIG. In this fixing device 26, both side plates 4 and 5 (side plate 5 is not shown) are connected to each other by connecting members 56a and 56b, and are integrated. The heating roller 1 and the pressure roller 3 are both supported by both side plates 4 and 5.

Connecting members 56a, 56 for connecting the side plates 4 and 5 to each other
A rail 58 is provided between b and the casing 48 connected to the machine frame 47 of the electrophotographic apparatus. The heating roller 1 and the pressure roller 3 can be taken out of the machine by moving the side plates 4 and 5 along the rail 58 in the direction A of FIG.

As shown in FIG. 11 and FIG. 12 which is a side view of FIG. 11, the casing 48 is mounted on four rollers 42 fixed to a machine frame 41 of the electrophotographic apparatus. Further, a pin 44 fixed to the machine frame 41 is fitted in an elongated hole 43 provided in the bottom plate 48a of the casing 48. The elongated hole 43 extends in the lateral direction with respect to the paper conveyance direction Q, that is, in the embodiment, at a substantially right angle,
Therefore, the casing 48 can move in the direction (XX direction) substantially perpendicular to the paper transport direction Q.

A roller moving means 45 for moving the casing 48 is arranged on the lower right side of the casing 48. The roller moving means 45 includes a screw 49 provided in a direction substantially perpendicular to the roll paper conveyance direction Q, and a slide member 50 meshing with the screw 49 and fixed to the bottom surface of the bottom of the casing 48. I have it. The screw 49 is connected to the output shaft of the stepping motor 51. When the stepping motor 51 rotates, the screw 49 rotates, and the slide member 50 moves in the axial direction of the screw 49, that is, the XX direction. Since the slide member 50 and the casing 48 are fixed to each other, the movement of the slide member 50 also moves the casing 48 in the XX direction. As a result, the heating roller 1 and the pressure roller 3 attached to the casing 48 simultaneously move in the XX direction.

In FIG. 10, two pins 52 fixed to the right side plate 4 are inserted into positioning holes provided in the machine frame 47 to position the heating roller 1 and the pressure roller 3. Two pins 53 fixed to the left end of casing 48
Is for inserting into a positioning hole provided in the left side plate 5 to similarly position the pressure roller 1 and the like.

In the case of the presently considered embodiment, means for detecting the skew of the roll paper as shown in FIG. 3 is prepared. When the skew of the roll paper is detected by the skew detecting means, the stepping motor 51 is operated by the CPU (not shown). In this case, the CPU, as shown in FIG.
Then, the stepping motor 51 is driven so that the heating roller 1 and the pressure roller 3 move. Due to the movement of the heating roller 1 and the pressure roller 3 in the Z direction, the roll paper P is forcibly moved in the Z direction while being sandwiched between the rollers 1 and 3. This corrects the skew.

The above is an embodiment in which the heating roller 1 and the pressure roller 3 are moved at the same time, but the same effect can be obtained by moving only one of them instead of moving both of them. be able to.

Effect According to the present invention, since the skew of the material is corrected in the fixing roller, the fixing work can be performed using the roller even when the material having a long length is used. Processing and thus a high speed electrophotographic process can be performed.

[Brief description of drawings]

FIG. 1 is an overall side sectional view of an example of an electrophotographic apparatus, FIG. 2 is a side sectional view of an example of a fixing device used in the electrophotographic apparatus, and FIG. 3 is a view of the apparatus of FIG. 2 seen from above. FIG. 4 is a schematic view showing an example of a means for detecting the skew of a material, FIG. 4 is a perspective view of a main portion of FIG. 2, and FIGS. 5 to 7 show main members of FIG. FIG. 8 is a diagram showing a state of paper conveyance by a pair of rollers, FIG. 9 is a side sectional view showing an embodiment of a fixing device according to the present invention, FIG. Similarly, it is a plan view of the fixing device, showing an example of means for moving the roller, FIG. 12 is a side view of FIG. 11, and FIG. 13 is a view showing a moving state of the fixing roller. FIG. 14 is a diagram showing a skewed state of the material. 1,3 …… Fixing roller 21a, 21b, 21c …… Material 19 …… Rotary shaft 7,8 …… Projection piece 9,10 …… Tension spring 36,37 …… Sensor 45 …… Roller moving means

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Claims (1)

(57) [Scope of utility model registration request] 1. A fixing device comprising at least two fixing rollers that rotate in contact with each other, and fix the toner image on the material while the material carrying the toner image is conveyed through the contact portion of the fixing roller. In the fixing device of the electrophotographic apparatus, a material deviation detecting means for detecting a deviation of the material in the lateral direction with respect to the material conveying direction, and at least one of the at least two rollers are provided in the material conveying direction. On the other hand, the roller moving means for moving the roller moving means to move in the lateral direction and the roller moving means so as to move the at least one roller in a direction opposite to the material deviation direction according to the deviation of the material detected by the material deviation detection means. And a control unit for controlling the fixing unit.