JPH06149106A - Fixing device for image forming device - Google Patents

Abstract

PURPOSE:To provide a fixing device for an image forming device making a pressure roller keep a temperatur enough for excellent fixing in accordance with environemt and a transfer body at the time of copying, and keeping the service life of a fixing roller for a long period without sticking excess oil onto an OHP sheet, degrading image quality and soiling a hand and a machine. CONSTITUTION:In the fixing device for the image forming device 1 where a pair of rollers is constituted of the fixing roller 2 and the pressure roller 5 being in press-contact with the fixing roller 2 to form a wipping part, an oil coating member 8 of the fixing roller 2, a cleaning member 10 of the fixing roller 2, a means attaching detaching the oil coating member 8 to/from the fixing roller 2 and a controller 11 controlling the temperature of the fixing rooller 2 in constant are provided, and the fixing is executed by passing transfer body 7 through the nipping part a means 11 controlling so as to rotate a pair of the rollers for a fixed time just before the OHP sheet or a thick paper is passed through the nipping part is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an image forming apparatus.

[0002]

2. Description of the Related Art In a conventional fixing device of an image forming apparatus in which a roller pair is composed of a fixing roller having a heating means and a temperature detecting means, and a pressure roller which is in pressure contact with the fixing roller, during the start-up when the power is turned on, After reaching the specified temperature, the roller pair is set to 1
When the temperature detecting means detects a predetermined temperature during the rotation time, the rotation of the roller pair is stopped to be in the ready state, and the oil application member is separated from the fixing roller during the fixing operation.

[0003]

In the conventional fixing device as described above, the temperature of the fixing roller is controlled, and the surface temperature of the pressure roller is lowered during standby, especially when the environmental temperature is low. If the transfer body is a thick paper, the amount of heat is insufficient, resulting in poor fixing, or if it is an OHP sheet, poor fixing and, in addition, dark color portions cause poor transparency. Further, when the fixing roller is rotated when the fixing operation is not performed and the oil applying member or the cleaning member is brought into contact with the fixing roller, the life of the fixing roller is shortened, and in the case of the OHP sheet, excess oil is used. However, there is a problem in that the image quality deteriorates and the hands and devices are soiled.

Therefore, an object of the present invention is to keep the pressure roller at a temperature sufficient for good fixing in response to the environment and the transfer member when copying, and to maintain the life of the fixing roller for a long period of time.
Another object of the present invention is to provide a fixing device of an image forming apparatus that does not deteriorate the image quality due to no excess oil adhering to the OHP sheet and does not stain the hands or equipment.

[0005]

In order to achieve the above object, the present invention provides a fixing roller having a heating means and a first temperature detecting means, and a fixing roller. An oil application member that forms a nip portion by forming a roller pair with a pressure roller that is in pressure contact with the fixing roller, and applies oil to the fixing roller, and a cleaning method that recovers residual oil that contacts the fixing roller and adheres to the fixing roller. A member, a means for contacting and separating the oil applying member with the fixing roller, and a control device for controlling the temperature of the fixing roller to a constant value are provided, and a transfer body holding an unfixed image is passed through the nip portion to perform fixing. In the fixing device of the image forming apparatus, when the OHP sheet or the thick paper is passed through the nip portion, a means for controlling the roller pair to rotate for a certain period of time is provided immediately before the passage. It is. According to a second aspect of the present invention, in the first aspect of the present invention, the pressure roller is provided with a second temperature detecting means, and the detection output thereof is input to the control device to pass the OHP sheet or the thick paper through the nip portion. Immediately before, when the roller pair is rotating for a certain period of time, when the temperature of the pressure roller reaches a predetermined temperature higher than the temperature before rotation, the control device controls to stop the rotation of the roller pair. . According to a third aspect of the present invention, in the first aspect of the present invention, a contact / separation unit for contacting / separating a member contacting the fixing roller with the fixing roller is provided. When rotating for a certain time,
The control device controls the driving of the contact / separation unit so that the member in contact with the fixing roller is separated from the fixing roller. According to a fourth aspect of the present invention, in the first aspect of the present invention, a cleaning member for cleaning the transfer body is provided on the downstream side of the roller pair which conveys the transfer body.

[0006]

In the invention as described above, in the invention of claim 1, immediately before the OHP sheet or the thick paper is passed through a nip portion formed by a roller pair composed of a fixing roller and a pressure roller, just before that. The means for controlling the rotation of the roller pair rotates the fixing roller and the pressure roller for a certain period of time. According to a second aspect of the present invention, in the first aspect of the present invention, the pressure roller is provided with a second temperature detecting means, and a detection output of the second temperature detecting means is input to the control device. When the OHP sheet or the thick paper is passed through the nip portion, Immediately before that, when the roller pair is rotating for a certain period of time and the temperature of the pressure roller reaches a predetermined temperature higher than the temperature before the rotation, the control device controls the rotation of the roller pair and stops the rotation. According to a third aspect of the present invention, in the first aspect of the present invention, a contacting / separating unit for contacting / separating a member contacting the fixing roller with the fixing roller is provided, and when the OHP sheet or the thick paper is passed through the nip portion, the roller is provided immediately before the passage. When the pair is rotating for a certain period of time, the control device controls the driving of the contacting / separating unit to separate the member in contact with the fixing roller from the fixing roller. According to a fourth aspect of the present invention, in the first aspect of the present invention, a cleaning member for cleaning the transfer body is provided on the downstream side of the roller pair which conveys the transfer body, and the cleaning member adheres to the transfer body discharged from the fixing roller and remains. Remove the oil you are using.

[0007]

Embodiments of the present invention are shown in FIGS. In FIG. 1, a pressure roller 5 is provided in pressure contact with a fixing roller 2 having a heater to form a roller pair to form a nip portion. A thermistor 4, an oil applying member 8 made of felt, and a cleaning blade 10 are sequentially arranged on the fixing roller 2 downstream from the nip portion in the rotational direction, and the output of the thermistor 4 is input to a control device 11 provided in a machine body (not shown). (Input 1) to control the electric power supplied to the heater of the fixing roller 2 to control the temperature of the fixing roller 2, and to provide a thermocouple 6 in contact with the pressure roller 5 and input the detection output thereof to the controller 11. (Input 2) and the temperature of the pressure roller 5 is detected.

An exit guide plate 16 and a cleaning roller 14 are provided in the conveying path of the transfer body 7 so as to be held between the roller pair and the paper discharge roller pair 17 so as to sandwich and convey the transfer body 7. The cleaning roller 14 is provided at a position where the transfer body 7 contacts the same surface as the surface where the transfer body 7 contacts the fixing roller 2.

As shown in FIG. 2, the oil applying member 8 is attached to one end of the holding member 9 held by the support shaft 20 and brought into contact with the fixing roller 2, and the other end is connected to the solenoid 13 via the plunger 12. The drive of the solenoid 13 is controlled by the control device 11 so that the oil application member 8 contacts and separates from the fixing roller 2. Similarly, although not shown, the cleaning blade 10 is also provided with a solenoid via a plunger in a holding member for holding the cleaning blade 10, and the controller 11 controls the driving of the solenoid so as to contact and separate from the fixing roller 2.

In this embodiment, the surface temperature of the fixing roller 2 rises and is controlled to T ₀ shown in FIG. 3 after the power is turned on, and the surface temperature of the pressure roller 5 is T ₁ which is almost the same as room temperature. Here, when the “thick paper / OHP sheet” key of the operation unit (not shown) is turned on at time t ₁ in order to perform copying with thick paper or OHP sheet, the fixing roller 2 and the pressure roller 5 are driven by the drive output of the control device 11. They rotate together and stop at t ₂ when a predetermined time has passed, and the surface temperature of the pressure roller 5 rises from T ₁ to T ₂ . At that time, the surface temperature of the fixing roller 2 is lowered to some extent, but since it is temperature controlled, it returns to the set temperature T ₀ . At the same time, the surface temperature of the pressure roller 5 is detected. When the surface temperature of the pressure roller 5 reaches T ₂ , fixing is performed, the rotation of the pressure roller 5 is stopped, and the control device 11 controls the driving so that the transfer body 7 is fed. I do. At this time, if the surface temperature of the pressure roller 5 is T ₂ or more, even if the “OHP sheet / thick paper” key is turned on, the copy operation is controlled to be stopped to stabilize the image quality.

When the "OHP sheet / thick paper" key is turned on and the fixing roller 2 and the pressure roller 5 start rotating, the controller 11 drives the solenoid 13 to separate the oil application member 8 from the fixing roller 2. To do. At the same time, the cleaning blade 10 may be controlled so as to be separated from the fixing roller 2.

OHP discharged from the nip portion of the roller pair
Since the oil adheres to the sheet, it is removed by passing it through the cleaning roller 14. The cleaning roller 14 is brought into contact with the transfer body 7 with a constant pressure by an urging member 15,
It is driven at a linear velocity slightly slower than the transport speed.

[0013]

The present invention is as described above, and the invention of claim 1 is a roller including a fixing roller having a heating means and a first temperature detecting means, and a pressure roller in pressure contact with the fixing roller. An oil application member that forms a nip portion by forming a pair and contacts the fixing roller to apply oil, a cleaning member that contacts the fixing roller and collects the residual oil adhering to the fixing roller, and the oil application member is fixed A fixing device for an image forming apparatus, comprising: a means for contacting and separating with a roller; and a control device for controlling the temperature of a fixing roller to be constant, and passing a transfer member holding an unfixed image through the nip portion to perform fixing, When the OHP sheet or the thick paper is passed through the nip portion, a means for controlling the roller pair so as to rotate for a predetermined time is provided immediately before the passage, so that the surface temperature of the pressure roller is increased to sufficiently fix the toner. It holds a temperature there is an effect that it is possible to form an image having good fixability and transparency. The invention of claim 2 is the same as the invention of claim 1,
The pressure roller is provided with the second temperature detecting means, and the detection output thereof is inputted to the control device so that when the OHP sheet or the thick paper is passed through the nip portion, immediately before that, when the roller pair is rotating for a predetermined time, When the temperature of the pressure roller reaches a predetermined temperature higher than the temperature before the rotation, the control device controls the rotation of the pair of rollers so that the fixing roller and the pressure roller are rotated only when necessary. The advantage is that the fixing roller and the pressure roller can be maintained for a long period of time. According to a third aspect of the present invention, in the first aspect of the present invention, a contacting / separating unit for contacting / separating a member contacting the fixing roller with the fixing roller is provided, and when the OHP sheet or the thick paper is passed through the nip portion, the roller pair is provided immediately before the passage. When rotating for a certain time,
Since the control device controls the driving of the contacting / separating means so as to separate the member in contact with the fixing roller from the fixing roller, there is an effect that the life of the fixing roller can be maintained for a long period of time. According to the invention of claim 4, in the invention of claim 1, since the cleaning member for cleaning the transfer body is provided on the downstream side of the roller pair which conveys the transfer body, the oil remaining on the transfer body is removed and the image quality is improved. There is an effect that it does not deteriorate, does not contaminate the hands, the paper discharge rollers and the device, and the oil does not adhere to the next transfer body to be contaminated.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of an embodiment of the present invention.

FIG. 2 is an oil applying member and a cleaning member of the above,
It is a schematic longitudinal cross-sectional view showing a portion with a contacting / separating means.

FIG. 3 is a characteristic diagram showing the relationship between the surface temperature of the fixing roller and the pressure roller and the elapsed time.

[Explanation of symbols]

 1 Fixing Device 2 Fixing Roller 3 Heater 4 Thermistor 5 Pressure Roller 6 Thermocouple 7 Transfer Body 8 Oil Applying Member 10 Cleaning Blade 11 Controller 12 Plunger 13 Solenoid 14 Cleaning Roller

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G03G 15/00 110 7369-2H 15/22 106 6830-2H

Claims (4)

[Claims] 1. A fixing roller having a heating means, a first temperature detecting means, and a pressure roller that is in pressure contact with the fixing roller to form a nip portion, and a roller is contacted with the fixing roller to form an oil. An oil applying member for applying the oil, a cleaning member for contacting the fixing roller to collect the residual oil adhering to the fixing roller, a means for contacting and separating the oil applying member with the fixing roller, and a control for controlling the temperature of the fixing roller constant. In a fixing device of an image forming apparatus, which includes a device and passes a transfer body holding an unfixed image through the nip portion to perform fixing, when the OHP sheet or the thick paper is passed through the nip portion, the roller is provided immediately before the passage. A fixing device for an image forming apparatus, characterized in that means for controlling the pair to rotate for a predetermined time is provided. 2. The pressure roller is provided with a second temperature detecting means,
When the detection output is input to the control device and the OHP sheet or the thick paper is passed through the nip portion, and the roller pair is rotating for a certain time immediately before that, the temperature of the pressure roller is higher than the temperature before the rotation. The fixing device of the image forming apparatus according to claim 1, wherein the control device controls the rotation of the roller pair to stop when the temperature reaches the temperature. 3. A contacting / separating means for contacting / separating a member contacting the fixing roller with the fixing roller is provided, and when the OHP sheet or the thick paper is passed through the nip portion, immediately before the roller pair is rotated for a predetermined time, The fixing device of the image forming apparatus according to claim 1, wherein the control device controls the driving of the contacting / separating unit so as to separate the member that is in contact with the fixing roller from the fixing roller. 4. The fixing device for an image forming apparatus according to claim 1, wherein a cleaning member for cleaning the transfer body is provided on a downstream side of the roller pair which conveys the transfer body.