JP2003122158A - Image fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an image fixing device capable of shortening the time taken until attaining a fixable temperature even from a state where a heat roller is not heated sufficiently and fixing a toner image on a paper for fixing without causing a faulty fixing even in the case of fixing an image on such a condition that the paper is brought into press-contact with the heat roller for a long time. SOLUTION: The heat roller has cylindrical shape, and a heater for imparting heat to the heat roller is arranged in the hollow part of the heat roller, and another heater is arranged on the outer peripheral surface side of the heat roller so as to heat the heat roller from both the outer peripheral surface side and the hollow part side, whereby the time taken until attaining the fixing feasible temperature even from the state where the heat roller is not heated sufficiently is shortened, and also the toner image is fixed without causing a faulty fixing even in the case of fixing the image on such a condition that the paper is brought into press-contact with the heat roller for a long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image fixing device adapted to fix a toner image on a sheet with a heat roller and a press roller.

[0002]

2. Description of the Related Art Generally, an image fixing device is provided with a heat roller and a press roller having a heat source inside. The press roller is provided so as to come into pressure contact with the heat roller,
A nip portion that nips the paper with both rollers is formed. Then, when the heat roller is heated, the paper on which the toner image is transferred is pressed at the nip portion to melt the toner, and the toner is uniformly spread and solidified on the surface of the paper.
As a result, the toner is fixed on the paper.

By the way, in the cylindrical heat roller,
The heat roller is required to have sufficient strength to withstand the pressure contact by the press roller, and in order to obtain that strength,
It is formed with a certain thickness.

Further, at the time of fixing an image, the paper takes away heat accumulated in the heat roller. Therefore, when fixing an image such that the paper is pressed against the heat roller for a long time, for example, when fixing one long paper over the entire length or fixing a plurality of papers continuously, If the heat is taken away more and more and the heat roller does not have enough heat, the temperature will drop immediately,
Since the temperature required for fixing cannot be obtained and the toner cannot be melted sufficiently, fixing failure occurs. Also from this, it is required that the heat roller can store sufficient heat, and the heat roller is formed to have a certain thickness.

[0005]

As described above, the heat roller is formed thick so that the strength and heat can be sufficiently stored. However, since the heat source is arranged only in the hollow portion of the heat roller, heating of the heat roller is performed only from the inside, and it takes a long time to heat the outer peripheral surface to the fixable temperature.

Therefore, in the copying machine, it takes a long time from the power-off state to the state where the power is turned on and the copying can be performed. Also, if the power of the copier is left on for a long time, it is set to enter the sleep mode to save power consumption, and even from this sleep mode until the copy can be performed. It takes a long time. However, the time from turning off the power to turning on the power to enable copying, and the time from the sleep mode to enabling copying (hereinafter, these two times are collectively referred to as Therefore, there is a problem in that the total time required for the copying work by the user is increased and the workability of the user of the copying machine is significantly reduced.

Further, in a color printer, since four color toners overlap each other to form a color, the toner image layer is often thick, and the area of an image printed on one sheet of paper such as a photograph is large. Often makes large records. In these cases, for example, in a color printer, the amount of toner to be fixed is inevitably large, the amount of heat required for fixing is also large, and it takes a longer time to heat the outer peripheral surface of the heat roller to a fixable temperature. This means that in a state where the heat roller is not sufficiently heated, the total printing time in the color printer takes longer, which also causes the workability of the color printer user to be significantly reduced. There is.

Further, when performing image fixing such that the paper is pressed against the heat roller for a long time, unless sufficient heat is stored in the heat roller, the temperature of the heat roller immediately decreases, and fixing is started from the middle. There is also a problem that fixing failure occurs such that the required temperature cannot be obtained and the toner cannot be melted sufficiently.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, in which the outer peripheral surface of the heat roller is quickly heated to a fixing-enabling temperature so that the heat roller is sufficiently heated. It is possible to shorten the total time required for image recording work even when the heat roller is not in use, and to keep the heat roller at the desired temperature even when the paper is pressed against the heat roller for a long time, and the image does not cause fixing failure. It is intended to provide a fixing device.

As a means for solving the problems, in the image fixing device, the invention of claim 1 is a hollow cylindrical heat roller, a press roller pressed against the heat roller, and a hollow of the heat roller. And a heater arranged on the outer peripheral surface side of the heat roller. According to the invention described in claim 1, since the heater is provided in the hollow portion and the outer peripheral surface side of the heat roller, there is an effect that the outer peripheral surface of the heat roller can be quickly raised to the fixing possible temperature. Further, the heat taken by the paper from the heat roller can be immediately supplied, so that the outer peripheral surface of the heat roller can always be kept at the fixing temperature.

Further, the invention of claim 2 is characterized in that the heater on the outer peripheral surface side of the heat roller is provided upstream of the nip portion between the heat roller and the press roller in the rotation direction of the heat roller. And According to the invention described in claim 2, since the distance from the ceramic heater to the nip portion is short, the portion of the heat roller 61 heated by the ceramic heater 23 can reach the nip portion 80 in a short time. Therefore, it is possible to supply more heat to the nip portion without allowing the heat accumulated in the heat roller by the ceramic heater to escape by natural heat dissipation.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described.

FIG. 1 is an internal side view of an image fixing device 60 according to an embodiment of the present invention. This image fixing device 60
Is a heat roller 61, a press roller 62, a guide plate 63, a peeling claw 66, a discharge roller 67, and a cleaning member 6.
8, a heater lamp 69, a ceramic heater 23, and the like, and the entire image fixing device is covered with a unit frame 8.

The heat roller 61 and the press roller 62 are arranged so as to roll up and down. Heat roller 61
Nip portion 8 for nipping the recording paper with the press roller 62
A guide plate 63 is provided so as to be inclined along the tangential direction of the nip portion 80 on the upstream side in the sheet conveyance direction of 0, and the sheet conveyed from a photoconductor drum (not shown) is conveyed to the nip portion 80. It is configured to guide you to.
The discharge roller 6 is provided on the downstream side of the nip portion 80 in the sheet conveying direction.
7 is provided, and the recording paper on which the image is fixed is sent to the paper discharge tray.

The heat roller 61 rotates in the direction of arrow E in the figure. The heat roller 61 is provided outside the heat roller 61.
The ceramic heater 23, the press roller 62, the peeling claw 66, and the cleaning member 68 are arranged in this order along the rotation direction of the. The ceramic heater 23 heats the outer peripheral surface of the heat roller 61 to a temperature at which fixing is possible. Nip part 8
At 0, the paper on which the toner image has been transferred is heated and pressed to fix the toner image to form a permanent image. The peeling claw 66 is provided such that the tip end portion thereof is in sliding contact with the outer peripheral surface of the heat roller 61, and plays a role of separating the sheet stuck to the heat roller 61 from the heat roller 61 when being pressed by the nip portion 80. Are doing The cleaning member 68 is made of a material such as felt, is disposed above the heat roller 61, and has its lower end slidably contacting the outer peripheral surface of the heat roller 61 to clean the surface of the heat roller 61.

The heat roller 61 has a cylindrical shape having a hollow 61h and is rotatably supported. In the hollow 61h of the heat roller 61, one rod-shaped heater lamp 69 such as a halogen lamp is fixedly provided as a heater at the center of the heat roller 61. The length of the heater lamp 69 is the same as that of the heat roller 61.
It is desirable that the width be the same. Further, the heat roller 61 is preferably made of a metal material having high heat conduction efficiency such as aluminum material and iron so that it can be heated quickly. Furthermore, when the surface layer 22 made of Teflon (registered trademark) coating is formed on the outer peripheral surface of the heat roller 61, the adhesion of toner to the heat roller 61 is further prevented. The press roller 62 is pressed against the heat roller 61 at a required pressure,
The press roller 62 also rotates along with the rotation of.

The ceramic heater 23 has a nip portion 8 on the upstream side of the nip portion 80 in the rotation direction of the heat roller 61.
It is provided at a position close to 0 so as to contact the outer peripheral surface of the heat roller 61. It is desirable that the ceramic heater 23 and the heat roller 61 have the same length. The ceramic heater 23 is a long ceramic substrate 2
4 has a resistance heating element 25 attached thereto, and the resistance heating element 25 is arranged in substantially the same width as the heat roller 61,
It is covered with a high hardness glass coat layer 26.
The resistance heating element 25 is provided so as to be in sliding contact with the surface layer 22 of the heat roller 61 via the glass coat layer 26. Further, since the surface layer 22 and the glass coat layer 26 have a small coefficient of friction, even if the heat roller 61 rotates and the surface layer 22 and the glass coat layer 26 slide, they do not easily wear.

When the resistance heating element 25 is energized, it generates heat over its entire length. Since the resistance heating element 25 is in direct contact with the outer peripheral surface of the heat roller 61 via the very thin glass coat layer 26, the heat from the resistance heating element 25 is quickly transferred to the outer peripheral surface of the heat roller 61. It Therefore, the outer peripheral surface of the heat roller 61 can be quickly heated to the fixing possible temperature.

The heater lamp 69 is also energized,
Heat is generated over its entire length. The heat generated by the heater lamp 69 is transferred to the heat roller 61 from the hollow side of the heat roller 61.

Now, in the image fixing device of this embodiment,
The sheet on which the toner image is transferred is sent to the nip portion 80 of the image fixing device 60. This heat roller 61 is heated by the heater lamp 69 from the hollow side,
Since the outer peripheral surface is quickly heated by the ceramic heater 23, the unfixed toner image on the sheet is melted by the heated heat roller. At the same time, since the paper is pressed by the nip portion 80, the toner image on the paper is fixed on the paper and becomes a permanent image.

As described above, in the image fixing device of this embodiment, in addition to the heater in the hollow portion, the heat roller 61
Since the ceramic heater 23 for heating the outer peripheral surface of the heat roller 61 is in sliding contact with the outer peripheral surface of the heat roller 61, the outer peripheral surface is heated to a temperature at which fixing can be performed quickly. Therefore, the effect of shortening the warm-up time can be obtained. Further, while the ceramic heater 23 temporarily heats a part of the outer peripheral surface of the heat roller 61, the heater lamp 69 moves from the hollow portion of the heat roller 61 to the heat roller 61.
Since the entire area of the
1 is supplying heat. Therefore, even if the heat of the heat roller 61 is taken by the nip portion 80, the heat is constantly supplied because the heat is constantly supplied, and the heat roller 61 is kept at a temperature sufficient for image fixing.

Further, in the image fixing apparatus of this embodiment, the ceramic heater 23 for heating the heat roller 61 is provided upstream of the nip portion 80 in the rotation direction of the heat roller and at a position near the nip portion 80. ing. Therefore, since the distance from the ceramic heater 23 to the nip portion 80 is short, the portion of the heat roller 61 heated by the ceramic heater 23 can reach the nip portion 80 in a short time. Therefore, the ceramic heater 23 supplies more heat to the nip portion 80 with almost no dissipation of the heat stored in the heat roller 61.
Therefore, although the cylindrical portion of the heat roller 61 is conventionally formed to have a thick wall for heat storage, the wall thickness can be reduced within a range in which pressure contact from the press roller 62 can be endured.

Further, for example, when the image fixing device is applied to a facsimile device, even if the image fixing device 60 is energized at the same time as the image is received, the heat roller 61 immediately reaches the fixing possible temperature. Images can be output immediately after reception.

In the present embodiment, the heater 23 for heating the outer peripheral side of the heat roller 61 has a linear shape and is provided so as to be in contact with the outer peripheral surface of the heat roller 61.
May be provided in non-contact with the outer peripheral surface of the heat roller 61.

FIG. 2 shows another embodiment of the present invention in which the heater for heating the outer peripheral side of the heat roller 61 is a heater lamp such as a halogen lamp. The heater lamp 69 is provided on the upstream side of the nip portion 80 in the rotation direction of the heat roller and at a position near the nip portion 80. The length of the heater lamp 69 and the width of the heat roller 61 are preferably the same. A reflection plate 70 is installed so as to surround the heater lamp 69, and heat generated by the heater lamp 69 is applied to the heat roller 61.
The heat generated by the heater lamp is concentrated on one side and is effectively transmitted to the heat roller 61. In this embodiment, since a halogen lamp, which is cheaper than a ceramic heater, is used as a heater for heating the outer peripheral surface of the heat roller 61, the cost can be reduced, and the same kind of parts as the heater lamp 69 on the hollow side of the heat roller can be provided. Since it is used, the effect that the efficiency of parts acquisition can be improved can be expected.

FIG. 3 shows another embodiment of the present invention in which a ceramic heater 23 for heating the outer peripheral side of the heat roller 61 is provided in a curved shape along the outer periphery of the heat roller 61. . The length of the ceramic heater 23 and the width of the heat roller 61 are preferably the same, and the gap between the ceramic heater 23 and the outer peripheral surface of the heat roller 61 is preferably 0.5 to 1.0 mm. As shown, a ceramic substrate 24 having a curved surface is arranged along the outer periphery of the heat roller 61, and a resistance heating element 25 is arranged on the heat roller 61 side. Replace the ceramic heater 23 with the heat roller 61.
In the case where the heat roller 61 is provided along the outer periphery of the heat roller 61, as compared with the case where the linear ceramic heater 23 is provided.
The ceramic heater 23 can heat over a wider range on the outer peripheral surface. Therefore, it takes a long time to receive heat from the vicinity of the ceramic heater 23 while the heat roller 61 makes one rotation.
It is possible to heat the outer peripheral surface to a fixing-enabling temperature more quickly. Further, in this embodiment, since the ceramic heater 23 and the heat roller 61 are provided in a non-contact state, there is no possibility of wear. If the ceramic heater 23 and the heat roller 61 are in contact with each other, it is possible to cover the surface of the heating element with a glass coating as shown in FIG.

Further, as another embodiment of the present invention, the heater inside the heat roller 61 and the heater outside may be used one by one by using a control mechanism. For example, when heating the heat roller 61 from a state where it is not sufficiently heated to a temperature at which fixing is possible, the heat roller 61
After heating from both the inside and the outside and heating the heat roller 61 sufficiently, only the heater inside the heat roller 61 is used for heating, and the external heater is not used, whereby power consumption can be saved. Get the effect.

An example of the embodiment of the present invention has been described above with reference to the drawings. However, the present invention is not limited to the matters shown in the above-mentioned embodiment, and the present invention can be modified and carried out without departing from the spirit of the invention. Be free.

[0029]

As described above, according to the image fixing device of the first aspect of the invention, since the heater is provided in the hollow portion and the outer peripheral surface side of the heat roller, the outer peripheral surface of the heat roller is quickly raised to the fixing possible temperature. You get the effect that you can. Further, since the heat taken by the paper from the heat roller can be immediately supplied, the effect that the outer peripheral surface of the heat roller can always be kept at the fixable temperature is obtained.

According to the image fixing device of the second aspect of the invention, since the distance from the ceramic heater to the nip portion is short, the portion of the heat roller 61 heated by the ceramic heater 23 reaches the nip portion 80 in a short time. Can reach For this reason, the heat stored in the heat roller by the ceramic heater is hardly released by natural heat dissipation,
An effect that more heat can be supplied to the nip portion is obtained.

[Brief description of drawings]

FIG. 1 is an internal sectional view of an image fixing device according to an embodiment of the present invention.

FIG. 2 is an internal cross-sectional view of an image fixing device section when a halogen lamp is used as a heater for heating the outer peripheral side of the heat roller according to the second embodiment of the present invention.

FIG. 3 is an internal cross-sectional view of an image fixing device section when a heater for heating the outer peripheral side of the heat roller according to the third embodiment of the present invention is provided along the outer periphery of the heat roller.

[Explanation of symbols]

8 unit frame 22 Surface layer 23 Ceramic heater 24 Ceramic substrate 25 Resistance heating element 26 Glass coat layer 60 image fixing device 61 heat roller 62 Press roller 63 Guide plate 66 peeling nail 67 discharge roller 68 Cleaning member 69 heater lamp 70 Reflector 80 Nip part

Claims (2)

[Claims] 1. A heat roller having a hollow cylindrical shape, a press roller in pressure contact with the heat roller, and a heater disposed on the hollow portion of the heat roller and on the outer peripheral surface side of the heat roller. Image fixing device. 2. The heater on the outer peripheral surface side of the heat roller,
The image fixing device according to claim 1, wherein the image fixing device is provided on an upstream side in a rotation direction of the heat roller with respect to a nip portion between the heat roller and the press roller.