JPH1115312A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device which enables a long-sized copy without a high mechanical precision and has high heat efficiency, a small electric-power consumption and a small rush current. SOLUTION: A first cover 4 and a second cover 5, which have facing openings, are installed on both the front side and the back side of a toner carrier of a transfer material across a passage of the transfer material. Plural surface heaters 6 separated from each other and a blower means 7 are installed inside the first cover 4. These heaters are arranged so as to have heating surfaces in the direction crossing the surface of the passing transfer material. Air is sent so that it may flow along the surface of these surface heaters 6, and hot air generated thereby is circulated inside the first cover 4. The second cover 5 is equipped with a heating means 25 located at such a position that the circulating flow is not disturbed by the heating means 25.

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 melting and fixing an unfixed powder toner carried on a transfer material surface by hot air, and more particularly, to a method for reducing the temperature of hot air circulating in a fixing device for a short time. The present invention relates to a fixing device that can be lifted by a fixing device.

[0002]

2. Description of the Related Art Conventionally, as a means for heating and fixing an unfixed powder toner image formed on a transfer material, an oven-type fixing device using radiant heat from a heater, a heating roller and a pressure roller are used. Roller-type fixing devices have been put to practical use in which a transfer material is passed through the fixing device and heat and pressure are applied to fix the material.

In particular, a roll heater type fixing device is relatively inexpensive and is preferably used mainly in a small-sized copying machine and the like, and an oven type fixing device is used as necessary in a large format copying machine and the like. Each of these methods has its own merits according to each method, but leaves some problems to be solved as described below (especially when they are used in a copying machine using a large format transfer material). ing.
On the other hand, as one proposal, a hot-air fixing device for fixing a toner image by blowing hot air onto a transfer material carrying a powder toner image is known, but such a method is still not practically sufficient in a satisfactory form. Not converted.

[0004]

2. Description of the Related Art Copiers and printers using electrophotographic methods are used in various fields. In particular, according to the application, for example, oval equipment for office use or large format for engineering drawings and graphics. It has been put to practical use as a device for use. Of these, for example, when implementing a large-format copying machine or large-format printer, an output image of 36 inches wide and 6 m in addition to fixed sizes such as A1 and A0 may be required according to the purpose of use. In particular, in special applications, a long copy of as long as 16 m may be required as a drawing of a ship, an airplane, or the like. The roll heater-type fixing device and the oven-type fixing device, which have been conventionally put into practical use, cannot respond to such a demand for the following reason. It has gained.

[0005] In the roll heater type fixing device, since the transfer material passes between the heating roller and the pressure roller, the peripheral speed of the photosensitive drum, the transfer speed of the transfer material transfer device, and the heat roller, If the speed difference between the pressure roller and the peripheral speed (“fixing speed”) is slight, tension or slack occurs in the transfer material, which causes a problem that an image formed on the transfer material is disturbed. That is,
If the transfer speed of the photosensitive drum and the transfer material transfer device becomes faster than the fixing speed, the transfer material is slackened, and the unfixed powder toner image comes into contact with the inside of the device and contaminates the image. Also, if the peripheral speed of the photosensitive drum or the transfer speed of the transfer material transfer device is lower than the fixing speed of the fixing device, the transfer material is in a tight state, and the transfer material slips on the heated fixing roller, causing wrinkles. Or print bleeding.

[0006] Therefore, in order to solve these problems, the precision of the size and speed of the entire apparatus including the photosensitive drum, the transfer material conveying device, and the fixing device must be extremely high. For example, when the processing accuracy of the diameter of the pressure roller of 60 mm is only shifted by ± 0.05 mm, when outputting a copy of 16 m, an error of ± 16 mm occurs. There is a limit in improving the accuracy of the entire apparatus, and it has been difficult to stably provide long copies without dimensional errors.

Further, an additional device such as applying silicone oil to the surface of the heating roller is required for offsetting the toner to the surface of the heating roller, and the structure of the fixing device becomes complicated.

Further, an infrared lamp is suitably used as a heat source inside the heating roller. However, since the power supply of this lamp is turned on and off to control the temperature, the rush current to the lamp is increased by a factor of ten. There is a problem that the above flows and voltage fluctuation of the peripheral device occurs.

On the other hand, in the case of the oven type fixing device, unlike the roll heater type fixing device, the transfer material can be fixed in a state of being separated from the heating source, so that the image quality such as the wrinkles and bleeding described above does not deteriorate and the image quality is long. It is possible to provide a scale copy. However, on the other hand, since the fixing is performed by the radiant heat from the hot plate, it is necessary to keep the heat source away from the transfer material by a distance necessary for safety in consideration of safety such as ignition or smoke at the time of paper jam. Since the thermal efficiency is reduced, the distance over which the transfer material passes must be increased, and the apparatus cannot be downsized.

[0010] Further, as described above, the hot-air fixing device can be reduced in size, safety in the case of paper jam, and the like.
A fixing device that can sufficiently satisfy low power consumption and the like has not been realized.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and enables long copying without requiring high mechanical precision, high thermal efficiency, low power consumption,
It is an object to provide a fixing device having a small inrush current.

Another object of the present invention is to provide a fixing device capable of raising the temperature inside the fixing device in a short time and forming hot air in a stable state.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a fixing device for passing a transfer material carrying a fusible powdery toner and thermally fixing the toner on the transfer material. First and second covers having openings facing each other are provided on the toner carrier surface side and the back side of the transfer material with the passage therebetween, and a plurality of planar heaters separated from each other are provided in the first cover. The heater is arranged so as to have a heating surface in a direction intersecting with the surface of the transfer material passing therethrough, and blows the air so as to flow along the surface of the planar heater and generates hot air generated in the first cover in the first cover. The second cover has a heating unit, and the second cover has a heating unit, and the heating unit is provided with a heating unit. Characterized in that provided at a position so as not to disturb.

Further, the heating means is provided on the back side of the second cover.

Further, the heating means comprises a cement resistor.

In such a configuration, air is blown from the blowing means so as to flow along the surfaces of the plurality of planar heaters, and the hot air generated by the blowing is circulated in the cover. The unfixed powder toner on the passing transfer material is uniformly melted and fixed.

On the other hand, the temperature inside the fixing device is raised in a short time by the heating means provided on the second cover which assists the heating of the inside of the fixing device by the planar heater, and the time for starting up the apparatus main body is shortened.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional side view of a fixing device according to the present invention. The fixing device 1 forms a well-known image by image forming means (not shown) provided around the photosensitive drum 2, and conveys a transfer material carrying an unfixed powder toner image on the transfer material. Located downstream of. The fixing device 1 is provided in the first cover 4 located on the surface of the transfer material that supports the powder toner, the second cover 5 located on the back side of the transfer material, and the first cover 4. A plurality of planar heaters 6 separated from each other, a blower 7 as a blowing means,
And a heating means 25 provided on the cover 5.

The first cover 4 and the second cover 5 are provided with openings 9a and 9b opposed to the transfer material conveying surface with the transfer material passage 8 interposed therebetween, and a space is formed by four walls. Each wall made of such a box-like body has a double structure in which an air layer or a heat insulating material layer is provided between the walls to prevent heat generated in the cover from escaping to the outside. The inside of each cover is preferably black-plated, or a black heat-resistant paint is applied to make the heat retention good, and the hot air formed as described later efficiently in the cover Each corner of the cover is formed in a round shape so as to be recirculated. Openings 9a and 9b of each cover have heat-resistant linear members 10a and 10b for guiding the transfer material.
Are provided obliquely along the transfer material transport direction. These linear members 10a and 10b have a role of guarding the transfer material from curling and touching a heat source described later in the cover.

The blower 7 as a blower is preferably a cross flow fan or a sirocco fan having a width covering the maximum size of the transfer material, and rotates in the direction of arrow A. The blower opening of the blower 7 may be located at a position where hot air circulates inside the cover when the transfer material passes therethrough, but is preferably a downstream position of the first cover 4 in the transfer material transport direction. And the arrow B
A recirculation in the direction can be generated, and the hot air can be efficiently applied to the transfer material. Reference numeral 11 denotes a shielding member made of a metal material for airflow for performing a suitable reflux in the cover. The blowing by the blower 7 is gentle,
When the hot air is applied to the unfixed powder toner carried on the transfer material, the air flow is set to such an amount that the toner does not soar.
Further, by applying the hot air from above the transfer material, the transfer material does not contact the linear member 10a provided on the first cover 4, and the toner image is not disturbed.

Reference numeral 6 denotes a sheet heater, which has a heating surface in a direction intersecting the surface of the transfer material passing therethrough, and a plurality of the sheet heaters 6 are separated from each other and sequentially arranged in the transfer material transport direction. It is provided to be inclined in the shearing direction. In the embodiment, the planar heater 6 is a belt-shaped heater, and is attached by heat-resistant insulating members 12 provided on both sides of the fixing device 1. The planar heater 6 is coated with black plating or black heat-resistant paint.

The heating means 25 heats the second cover 5 and is used as a preliminary heater at the time of starting up the apparatus main body or at the time of temperature control. Therefore, the heater 25 consumes less power than the planar heater. Is used. For example, a thin plate-shaped ceramic heater extending in the width direction of the transfer material, or a plurality of cement resistors arranged at predetermined intervals are preferably used as the heating means. These heaters are fixed to the second cover 5 with screws or a heat-resistant adhesive.

The preferred arrangement of the heating means is such that it is provided on the outer wall side of the second cover 5 as shown in FIG. 1, whereby even if the transfer material has not passed through, Is performed in the fixing device without being disturbed. Further, the inner wall of the second cover 5 may be provided as long as the shape and the position of the heating means 25 do not disturb the reflux.

The method of controlling the heating means will be described.
For example, when the apparatus main body is started up in the first morning or the like, the temperature inside the fixing device 1 is almost close to room temperature. In order to raise the temperature to the set temperature in a time as short as possible from this state, the above-described planar heater 6 and the heating means 25 are simultaneously energized, and the blower 7 is operated in the fixing device 1. Thereby, the heat of the sheet heater 6 and the heating means 25 can be efficiently received by the air blown from the blower 7 along the sheet heater 6 heated inside the fixing device 1 and converted into hot air.

A discharge roller pair 16 composed of a driving roller 14 and a driven roller 15 is provided near the transfer material outlet 13 in the fixing device 1, and discharges the passed transfer material to the outside. By providing the discharge roller pair 16 near the outlet 13, escape of hot air from the fixing device 1 is prevented.

FIG. 2 is a view of the first cover 4 as viewed from the direction of arrow C in FIG. 1, and shows a planar heater 6 having a flat surface extending in the width direction of the fixing device 1, and a blowing means. 2 shows an arrangement state with the blower 7. The ceramic heat-resistant insulating member 12 is provided on the side surface of the fixing device 1, and the end of the sheet heater 6 is attached to a mounting hole provided in the heat-resistant insulating member 12. I have. The shape and size of the planar heater 6 are not particularly limited, but it is preferable that the heater can be heated and cooled quickly on demand. In the embodiment, as the sheet heater 6, a rolled nichrome wire is preferably used, and a strip-shaped nichrome wire having a width of 18 mm and a thickness of 0.35 mm is used. The temperature of the sheet heater 6 rises very quickly by energization and heats it. By blowing air along the sheet heater 6, the heat of the sheet heater 6 can be efficiently received and converted into hot air. By circulating the hot air inside the fixing device 1, the hot air can be raised to a predetermined temperature without escaping to the outside.

Further, even if a trouble such as a paper jam occurs in the fixing device 1 (or in other portions in a copying machine or the like), a stop signal of the transfer material conveying system is detected to supply electricity to the sheet heater 6 and blow air. By stopping the driving of the blower 7 as a means, the heat of the planar heater 6 suddenly drops, and when the blower 7 is stopped, the hot air does not flow to the transfer material. There is no.

Reference numeral 17 denotes a motor for driving the cross flow fan. In the embodiment, the linear members 10a and 10b provided in the openings 9a and 9b of the respective covers described above are 0.2 mm.
A stainless steel wire of about mm is stretched around the transfer material at a predetermined distance slightly obliquely with respect to the traveling direction of the transfer material as shown in the figure.

FIG. 3 shows a perspective view of FIG. In this example, unlike the above-described example, the planar heater 6 is corrugated, and the surface area of the planar heater 6 is made larger than that in a state where the normal heater is stretched. As a result, the amount of heat generated from the planar heater 6 increases, and the size of the apparatus is reduced.

The planar heaters 6 separated from each other are provided with a blower 7
In order to prevent an accident that adjacent planar heaters 6 come into contact with each other due to the air blow, a heat-resistant insulating guide 18 is provided. The heat-resistant insulating guide 18 has a cutout 19 that sandwiches the planar heater 6 as shown in the figure, and is provided so as to cross the stretched planar heater 6. The heat-resistant insulating guide 18 is preferably made of mica, and is provided at a predetermined interval.

Reference numeral 21 denotes a spur-shaped holding plate having a sharply-pointed tip end for rotatably guiding the transfer material fed from the conveyor belt 3 to the entrance 20 of the fixing device. Since the holding plate 21 has a small contact area (area) with the transfer material, it can guide the unfixed unfixed toner on the transfer material to the passage of the fixing device 1 without disturbing.

As an example of a method for controlling the fixing device 1 on demand, it is necessary to control the temperature inside the fixing device 1 to a predetermined temperature immediately before the transfer material is conveyed into the fixing device 1. For this reason, the time when the transfer material arrives at the fixing device 1 is detected in advance, and the sheet heater 6 and the blower 7 are driven, and the thermistor 2 provided inside the fixing device 1 is driven.
The temperature inside the fixing device 1 is raised so that the temperature becomes a predetermined temperature by the detection of (2). During this time, the temperature can be raised in a short time by continuously energizing the heating means.

The operation of the fixing device 1 having such a configuration will be described. In FIG. 1, a transfer material carrying unfixed powder toner by a well-known image forming method is transported by a transport belt 3 to an entrance 20 of the fixing device 1. The leading end of the transfer material is conveyed into the fixing device 1 while being pressed by the pressing plate 21 against the linear member 10b located below. The time required for the transfer material to be conveyed to the fixing device 1 is calculated by the detection means, and the fixing temperature in the fixing device 1 is set to a predetermined temperature within this time beforehand by the sheet heater 6 and the heating means. 25, and the blower 7 as a blower is driven to circulate hot air in both the covers of the fixing device 1 in the direction of arrow B.

Next, hot air hits the passing transfer material uniformly and without disturbing the toner image, and the transfer material is conveyed while being pressed against the linear member provided on the second cover 10b. The unfixed powder toner carried on the toner is melted and fixed. The transfer material is further conveyed and discharged outside by a discharge roller pair 16. After the transfer material has been completely discharged, this is detected and the energization of the sheet heater 6 and the heating means 25 is cut off, and the driving of the air blowing means is stopped. These are to prevent unnecessary heat from leaking from the fixing device to other sections in the copying machine, for example, an image forming section such as the photosensitive drum 2 as much as possible. Alternatively, the heating means 25 may be continuously energized.

Further, by forming the planar heater 6 into a unit together with a heat-resistant insulating member, it can be integrally pulled out and mounted from the fixing device, thereby providing a fixing device more usable in maintenance and the like. .

Although the configuration in which the planar heater 6 is inclined in the direction along the traveling direction of the transfer material has been exemplified, the present invention is not limited to this configuration. The orientation may be substantially parallel or at right angles to the transfer material.

[0037]

The fixing device of the present invention has a structure in which hot air leakage preventing means is provided at the entrance and exit, and blows air along the surface of the planar heater to efficiently convert the heat of the heated planar heater to hot air. Since the hot air is recirculated in the fixing device, the leakage of the hot air to the outside of the fixing device can be minimized, and the peripheral devices such as the photosensitive drum and the cleaning device are not adversely affected. Further, it is possible to obtain a fixing device having higher thermal efficiency and lower power consumption than other fixing devices, and furthermore, since the heating means is provided in the second cover, the temperature inside the fixing device can be raised in a short time. it can.

Further, the transfer material passing by the hot air circulating is conveyed while being pressed downward, so that the toner carrying surface of the transfer material can be fixed without contacting the inside of the apparatus.

Even if the transfer material stops in the fixing device due to a trouble in the image forming apparatus, the temperature in the fixing device is reduced only by detecting this and stopping the sheet heater and the blowing means. The safety is high because it drops rapidly. A desired fixing temperature can be set by appropriately selecting the interval and the number of the planar heaters.

[Brief description of the drawings]

FIG. 1 is a schematic sectional side view showing a fixing device according to the present invention.

FIG. 2 is a state diagram of the fixing device viewed from the direction of arrow C in FIG. 1;

FIG. 3 is a perspective view of FIG. 2;

[Explanation of symbols]

 Reference Signs List 1 fixing device 2 photosensitive drum 3 transport belt 4 first cover 5 second cover 6 planar heater 7 blower 8 passage 9a, 9b opening 10a, 10b linear member 11 shielding member 12 heat-resistant insulating member 13 outlet 14 drive roller 15 Driven roller 16 discharge roller pair 17 motor 18 heat-resistant insulating guide 19 notch 20 inlet 21 holding plate 22 thermistor 25 heating means

Claims (3)

[Claims] 1. A fixing device in which a transfer material carrying a fusible powder toner is passed and a toner is thermally fixed on the transfer material, wherein the transfer material is disposed between a surface of the transfer material and a back surface of the transfer material with a transfer material passage interposed therebetween. First and second covers having openings facing each other, a plurality of planar heaters spaced apart from each other in the first cover, and these heaters are arranged in a direction intersecting a surface of the transfer material passing therethrough. It is arranged so as to have a heating surface, and an air blowing means is provided for blowing air to flow along the surface of these planar heaters and for circulating hot air generated thereby in the cover. The second cover has a heating means, and the heating means is provided at a position which does not disturb the reflux. apparatus. 2. The fixing device according to claim 1, wherein the heating unit is provided on an outer wall of the second cover. 3. A fixing device according to claim 2, wherein said heating means comprises a cement resistor.