JPH0710368Y2 - Roll type fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a heating roller type fixing device, and in particular, the heat roller has a good temperature distribution state even when a small size sheet is continuously fixed. The present invention relates to a fixing device that can maintain the above-mentioned characteristics and can perform the fixing operation in a good state.

(Prior Art) In an image forming apparatus that uses a dry toner, such as an electronic copying machine or a laser printer that has been generally used, a toner image is formed on an image bearing member such as a photosensitive drum, and the toner is formed. A means for transferring an image onto a sheet and fixing it through a fixing device is used.

As an apparatus for fixing the toner image on the sheet as described above, an oven type apparatus, a flash fixing apparatus, and a pressure type apparatus are used, but in general, a heating roller type fixing apparatus is used. Many are used.

In this heating roller type fixing device, a pair of rollers are arranged so as to sandwich the paper conveyance path, and one or both of the rollers are provided with a heating source such as a heat lamp.
When a sheet carrying an unfixed toner image is passed through while nipping between the rollers, the sheet is heated and pressed to melt the toner and fix it on the sheet. Is.

An image forming apparatus using the above-described fixing device is configured, for example, as shown in FIG. In the image forming apparatus shown in FIG. 13, a photoconductor drum 60 is used as an image carrier, and a peripheral of the photoconductor drum is a device using a xerographic system such as a normal copying machine. Similarly, the charging corotron 61, the developing device 62,
In addition to the transfer / peeling corotron 63 and the like, various devices such as a cleaning device and a charge corotron are arranged. And
Image information of a document obtained from an image reading device or the like is written on a photosensitive drum to form an electrostatic latent image, and toner is attached to the electrostatic latent image to form a visible toner image. Is transferred to the paper.

In addition, as for the paper, from the paper storage device such as the paper feed cassette 65,
Transfer and peeling corotron supplied by paper feed roller 66
The toner image is transferred by the discharge of 63, and the paper carrying the unfixed toner image is moved by the conveyor belt device 64 or the like, and the heating roller 20 and the pressure roller 10 of the fixing device 1 are passed through the guide plate 40. It is introduced into the nip portion by and the fixing action is performed. Then, the sheet that has been fixed and completed as a recording sheet is accommodated in a discharge tray or the like via the transport roller device 67.

In the general image forming apparatus configured as described above, as the fixing device 1, a device having a configuration as shown in FIG. 14 is used. The fixing device 1 shown in FIG. 14 is an example shown in Japanese Patent Application No. 55-133072 and the like. The fixing device 1 is composed of a pressure roller 10 and a heating roller 20, and The rollers are supported on the side frames 2 and 3 of the apparatus through bearings 14 and 22, and a predetermined pressing force is applied between the rollers.

Further, the pressure roller 10 is provided on the surface of the metal pipe 11,
It is formed by covering the rubber layer 12 with a predetermined thickness,
The pressure roller is configured to be driven via a drive sprocket 15 provided on the shaft. The heating roller 20 arranged corresponding to the pressure roller is one in which the surface of a metal core is coated with fluororesin, a heat source 25 such as a halogen lamp is provided inside the roller, and The surface temperature is maintained at about 200 ° C.

Then, in the fixing device configured as described above,
The unfixed toner image carried on the paper is introduced into the nip portion of both rollers so as to correspond to the heating roller, and the toner of the heating roller melts the toner,
When the melted toner is pressed by the pressure roller from the rear portion of the paper, it enters the inside of the fiber of the paper and the fixing is performed.

(Problems to be Solved by the Invention) In the conventional fixing device as described above, there are many problems to be solved in terms of a to d described below.

a: Controlling the temperature of the heating roller, b: How to support the heating lamp of the heating roller to obtain a good copy, c: Setting the position of the guide plate for introducing the paper between both rollers, d: A method of applying oil to the surface of the heating roller, and in order to solve many problems as described above,
There are conventional examples as described below.

a: The problem of managing the temperature distribution of the heat roller of the fixing device is, for example, in the case of fixing a small size paper in an image forming apparatus capable of forming a copy using a large size paper. Since only a part of the fixing device in the width direction is used, the temperature of the other part may be unnecessarily increased.

Therefore, in order to solve the above-mentioned problem
As shown in Japanese Laid-Open Patent Publication No. 53-17740, a heat generating lamp formed by dividing a heat generating portion is provided.
Then, the heat generation of the heat generating lamp is controlled in accordance with the information from the temperature sensor arranged at a predetermined interval with respect to the heating roller, and the temperature of the fixing device is managed.

However, as described above, the device in which the heat-generating lamp is composed of a plurality of heating elements having different lengths can work well when applied to a device using a standard size sheet, When fixing paper with a width of about 50 mm, such as receipts used in supermarkets,
There is a problem that the heat distribution tends to be non-uniform in the length direction of the heating roller.

However, continuous copying on special paper as described above is particularly required in a specific field, but when using an ordinary electronic copying machine or the like, particularly small size paper is used. However, there is a drawback that a copy cannot be obtained in good condition.

For example, in a conventional heating roller as shown in FIG. 11, three heating lamps 2 are provided inside the heating roller 20.
5, 25a and 25b are arranged in parallel, and each heat generating lamp is provided with a heat generating portion as shown in the graph of FIG.

When fixing, the temperature of each part is detected by multiple sensors provided on the heating roller, and the power supply circuit of the heat lamp is turned on / off to raise the temperature abnormally in the non-paper passing part. Means for preventing the occurrence of

However, as described above, in the case of a device provided with a plurality of heat generating lamps, the number of sensors and heat generating lamps is large, and the control circuit is complicated, so that the manufacturing cost of the fixing device is increased. There is a problem such as doing.

b: Further, as to the method of supporting the heat generating lamp, as shown in FIG. 15, the heat generating lamp 25 generates heat, so that the heat generating lamp 25 expands and contracts in the lengthwise direction. The portions are supported by cover members 38 and 39, the end portions of the heat generating lamp are covered, and side caps 36 and 37 are arranged on the side portions of these cover members.

Then, a means for preventing other members from coming into contact with the high-temperature heat-generating lamp or releasing the heat of the heat-generating lamp to the outside to excessively heat other equipment is used. Further, the supporting members on both sides of the heat generating lamp are arranged outside the side frames 2 and 3 which support the heating roller 20. Means such as attaching a cap are used.

However, in the case of the conventional heating lamp supporting system configured as described above, since the mounting position of the cover member is set corresponding to the expansion and contraction of the heating lamp in the length direction, There is a problem that the heating lamp cannot be fixed completely. When the heat-generating lamp moves in the length direction, the temperature distribution of the heating roller is not constant, which may cause a problem in copy quality.

Further, as described above, the use of a plurality of supporting members causes problems such as an increase in the number of parts of the fixing device and a large amount of labor required for assembly.

c: In addition to the problem of the heat lamp, there is a problem of adjusting the position of the guide plate used for introducing the paper into the fixing device. This requires that the height at which the paper is introduced between both rollers be different in the case of thick paper such as postcards and the case of paper used for normal copying. That is, in the case where the paper is relatively thin and has a weak stiffness, as in the case of a normal copy paper, after the leading edge of the paper comes into contact with the heating roller, the both ends are rotated in accordance with the rotation of the heating roller. It is necessary to be guided to the nip position of the roller, but in the case of thick and strong paper such as postcards, it is required to be introduced directly to the nip position. .

However, in the conventional fixing device, the rocking mechanism of the guide plate is rarely provided, and it is not possible to guide the paper in a good state for all kinds of paper and make a copy. was there.

Also, when a mechanism for manually swinging the guide plate is provided, if the guide plate is not swinged and then returned to the original position, the next copy may be hindered. There was a problem such as.

d: Further, applying an offset preventing liquid to the surface of the heating roller is a means generally performed in the past, for example, an apparatus as disclosed in JP-A-60-143372 is known. There is. In this conventional device,
A cleaning web made of a heat-resistant non-woven fabric is used on the surface of the heating roller to clean the toner, paper dust and the like adhering to the surface of the roller and to apply silicone oil and the like.

However, as described above, in the apparatus using the web, it is difficult to detect the end portion of the web, and sometimes the web cannot operate in a good state,
The fixing device may be actuated and various troubles may occur. On the other hand, there are cases in which the means for detecting the end portion of the web is constituted by a microswitch and the arm is pressed against the web to notify that the web is gone. However, when the switch means is used, the signal is output only when the web completely disappears, so that the roller surface can be satisfactorily coated with oil or the like immediately before that. There was a problem such as no.

(Purpose of the Invention) The present invention solves the above-mentioned drawbacks of the conventionally used apparatus, and a paper sensor is arranged in the upstream portion of the fixing device so that paper of a size smaller than the standard size can be used. When detected, a means for setting the paper feed interval to a large value is provided to prevent uneven distribution of temperature in the fixing device, and to manage temperature and maintain the temperature without complicating the fixing device. It is an object of the present invention to provide a device that can perform the above-mentioned method.

(Means and Actions for Solving Problems) According to the present invention, a sheet carrying an unfixed toner image is passed through a nip portion of a heating roller and a pressure roller, and heating and pressure are applied between the rollers. The present invention relates to an apparatus for performing and fixing. In the present invention, a heat generating lamp is provided so as to penetrate through the central portion of the heating roller, a plurality of paper sensors are arranged in a paper transport path upstream of the fixing device, and one of the paper sensors is fixed. It is used as a paper sensor for detecting paper of a size or smaller, and when the paper sensor detects a small size of paper, the paper conveyance interval is set large and the heat distribution of the rollers can be averaged. are doing.

In the apparatus of the present invention, one of the paper sensors arranged in the paper transport path upstream of the fixing device is used as a paper sensor for detecting paper of a standard size or smaller, and the paper sensor detects small paper If a program is issued to the control device to output a command to change the paper transport mode when it detects a paper feed, the paper transport interval in the paper transport path is set large, and the heat distribution of the rollers is averaged. Can be configured to do.

As described above, when a small size sheet is passed through the fixing device, by setting a large sheet conveyance interval,
It is possible to prevent the temperature of the heating roller from largely changing locally, and to prevent uneven fixing or the like when fixing a large-sized sheet thereafter.

(Example) The structure of the roll-type fixing device of the present invention will be described with reference to the illustrated example. The fixing device of the present invention is used for an xerographic image forming apparatus such as an electronic copying machine or a laser printer. For example, a general image as shown in the conventional example of FIG. In a forming apparatus, after transferring a toner image formed on an image bearing member such as a photoconductor drum onto a sheet, the sheet carrying the toner image is introduced into a heating roller type fixing device to make a copy or the like. To be able to. Further, the fixing device of the present invention described below is a normal heating roller type device provided with a heating roller and a pressure roller. As shown in FIG. And a pressure roller that is pressed against the heat roller with a predetermined pressing force.

a: Controlling the temperature of the fixing device In the image forming apparatus of the present invention, as shown in FIG. 9, sensors 29 and 29a for detecting the size of the paper are provided in the paper conveyance path upstream of the fixing device. Means may be provided to automatically detect the size of the paper placed and introduced into the fixing device.

The detection means by the paper sensor is used as information of the paper feed control circuit of the image forming apparatus, and when a paper of a size smaller than the standard size of paper is detected, the paper conveyance interval is increased. A program for sheet conveyance is set in the control device so that the control is performed.

In addition, the paper sensor 2 provided in the paper transport path of the present invention
Of the 9 and 29a, the sensor 29 is provided, for example, at a position corresponding to the width of a B5 size sheet, and can detect a sheet of a size smaller than that size. In addition, the paper sensor 29a
Is disposed at a position where it can detect all sizes of paper that can be run in the image forming apparatus, and the length of the paper can be detected by the detection time of the sensor.

Then, by using the sheet sensor arranged as described above, when a sheet of a size smaller than the standard size is detected, the sheet conveyance interval is set large and the idling time of the fixing device is set long. This makes it possible to control the temperature distribution of the fixing device to be uniform.

Therefore, when the control method of the fixing device of the present invention is used, the paper of a standard size or smaller is passed,
As shown in the graph of the figure, even if only a part of the temperature is decreased and the temperature of the non-sheet passing portion is increased, the non-uniformity of the temperature distribution can be eliminated. That is, by continuing idle rotation of the fixing device for a long time, the temperature distribution in the nip portion is made uniform by heat conduction in the length direction of the roller.

Then, it is possible to prevent only a specific portion of the heating roller from becoming abnormally high in temperature, so that even when a copy is made using a wide paper thereafter, an inconvenient state does not occur.

In the graph shown in FIG. 10, when the above-mentioned measures are taken, if the sheet conveyance interval is tripled, the temperature rise in the non-sheet passing portion will be as shown by the chain line. Can be relatively reduced.

Therefore, in the fixing device of the present invention, when a small size paper is passed, the drive of each mechanism of the image forming apparatus is controlled by inputting the information detected by the paper sensor to the control device. By the program set in the control device, the paper movement interval is automatically set, and the fixing operation can be performed in a state where the temperature distribution of the rollers of the fixing device becomes uniform.

b: Supporting device for heat generating lamp of pressure roller In the fixing device 1 of the present invention shown in FIGS. 1 to 3, the housing is composed of the frames 2 and 3 on both sides, the upper cover 4, etc. Heating roller inside
20 and a pressure roller 10 are provided.

In the fixing device 1 of the present invention, the heating roller 20 is provided with the gear 23, and a driving device is connected to the gear to drive the pressure roller 10, and the pressure roller 10 can be rotated in conjunction with the heating roller. Is configured as follows.

In the fixing device 1 of the present invention described above, the main body of the heating roller 20 is composed of the pipe 21, and both sides of the pipe 21 are supported to the frame through the bearings 22. The lamp 25 is provided so as to be supported by the frame.

The exothermic lamp 25 of the present invention is projected from both side ends of the pipe 21 by a predetermined length, one end of which is supported by the cover member 35 and the other end of which is supported by the cap support 30. Is configured as follows.

The cap support 30 of the present invention is constructed as shown in FIGS. The cap support is formed of a plastic or the like in a cap shape, and includes a tapered cylindrical main body 31 and a protrusion 33 protruding outward from the central portion, and is screwed around the main body. A plurality of parts 32 are provided.

Then, one end of the heat generating lamp is inserted into the protrusion 33, and the cord 26 pulled out from the heat generating lamp is held so as to be engaged with the tip of the protrusion, and the end of the cord is The part is guided along the wall at the end of the protrusion 33 and pulled out from the lower opening 33a. A cover member 35 is arranged at the other end of the heat generating lamp 25 so as to project from the frame 2, and the heat generating lamp is held by using the cover member.

The cover member 35 is made of a plate member made of metal, has a hole for inserting the heat generating lamp 25, and the end of the heat generating lamp is inserted into the hole, but the cover member 35 is provided so as to project from the heat generating lamp. The flange 25a is locked inside the cover member to prevent the heat lamp from moving to the outside of the roller.

Therefore, in the heating roller 20 of the present invention, the heat generating lamp is supported by the cover member 35 provided on the frame 2 and the cap support 30 provided on the side frame 3. Then, one end of the heat generating lamp is attached to the cover member 35.
And the other end is held in a state of being pressed axially by the cap support 30 via the cord 26, so that the heat generating lamp 25 is moved axially,
It is possible to prevent backlash from occurring in the fixed portion.

Further, in the fixing device of the present invention, as in the case of the conventional device, the heat insulating cover 5 is provided on the upper part of the housing. However, as shown in FIGS. 1 and 2, the cover member 35 is provided. The hanging portion 6 formed by bending the end portion of the heat insulating cover 5 downward is provided on the side supported by. The hanging portion 6 covers the side portion of the heating roller to prevent an operator or the like from coming into contact with a high temperature portion.

Therefore, in the fixing device of the present invention, unlike the conventional fixing device, the high temperature portion of the side portion of the heating roller can be protected without using the side cap.

c: Oscillating device for guide plate In the embodiment of the present invention shown in FIGS. 4 to 5b, a guide plate 40 is provided for guiding the paper to the nip portion between both rollers of the fixing device. In that case, the guide plate 40
In addition to providing the rocking means on the above, a means for enabling the position of the guide plate to be displayed is disclosed.

In a normal heating roller type fixing device, when fixing to a sheet called plain paper, as shown in FIG. 4, the end portion of the guide plate 40 is placed against the nip portion between both rollers. A means for causing the leading edge of the sheet to come into contact with the heating roller first and then being moved according to the rotation of the heating roller to enter the nip portion is used.

Also, when fixing thick and strong paper such as postcards, set the end of the guide plate lower than the nip position as shown in Fig. It must be introduced in the interim.

As described above, in order to set the sheet introduction position by swinging the guide plate 40, in the fixing device of the present invention, as shown in FIGS. The plate 40 is supported by a shaft 41, and a cam 42 is provided below the guide plate.

A lever 44 is provided at the end of the shaft 43 of the cam 42, and the guide plate 40 can be swung by swinging the lever 44. A spring 47 is provided at the end of 40,
The guide plate is configured to be pressed by the cam.

In the fixing device of the present invention described above, the lever 44
Is manually swung, and two sensors 45 and 46 are provided on both sides of the swing range of the lever, as shown in FIG. 5b, to determine the position where the lever is swung. The information is detected and the information is displayed on the display unit provided on the control panel or the like.

In the case of the guide plate provided with the swinging mechanism of the guide plate of the present invention, when copying is performed using thick paper, the fact is displayed on the display unit, so the guide plate is returned to the normal state. Even if the operator who uses the image forming apparatus later does not have to
The state of the fixing device can be easily determined.

Then, it becomes possible to position the guide plate according to the paper to be copied later, and by mistake,
By setting the guide plate at a position that does not fit the paper, it is possible to prevent problems such as creating a miscopy.

That is, the swinging device for the guide plate shown in the embodiment of the present invention is configured so that the state of the guide plate can be easily discriminated from the outside of the device, and its display means is arbitrary. Mechanisms can be used and, as previously described, other mechanism devices can be formed in addition to the means shown to indicate the position of the lever.

d: Structure of Device for Applying Oil to Heating Roller As shown in FIG. 6, in the fixing device of the present invention, the offset prevention liquid applying device 50 is applied to the heating roller 20.
And the web 51 of the coating device is pressed against the surface of the heating roller 20 by the tension roller 52, and the offset preventing liquid is applied to the surface of the roller. Arranging this offset prevention liquid coating device is also used in the conventional technical means, but in the case of the device of the present invention, when the web 51 is supplied and the shaft of the supply roll 53 is exposed. , A means that can detect that and output an alarm or the like is used.

That is, in the offset prevention liquid coating apparatus 50 of the present invention, the web 51 is wound around the supply roller 53 and the take-up roller 55 as shown in FIGS. 6 and 7.
Then, the web 51 before use which is wound around the supply roller 53.
a toward the take-up roller 55,
A tension roller 52 is provided between the two rollers,
The heating roller 20 is pressed.

This web 51 uses a system in which the take-up roller 55 is driven and the web is moved little by little every time when a certain number of copies are made, but the web is used for offset prevention on the surface of the heating roller. It is used for applying silicon oil and for removing toner, paper dust, etc. adhering to the surface of the heating roller.

In the offset prevention liquid coating device of the present invention described above,
The shaft 53a of the supply roller 53 is made of a conductive material such as aluminum, and the shaft is connected to the ground 54. Also,
A terminal 56 is arranged with respect to the supply roller, a predetermined electric potential is applied to the terminal 56, and a sensor is provided in the circuit.

When the pre-use web 51a wound around the supply roller 53 disappears and the shaft 53a is exposed, the terminal 56 comes into contact with the shaft 53a to form a circuit through which a current flows. It is possible to detect and instruct replacement of the offset prevention liquid coating device.

That is, in the offset prevention liquid coating apparatus of the present invention, as shown in FIG. 8, by setting the arrangement position of the terminals 56 as shown in the drawing, the offset prevention liquid coating apparatus immediately before the web is completely lost. Since it is possible to output the replacement command, it is possible to prevent the occurrence of troubles caused by the complete disappearance of the offset prevention liquid on the surface of the heating roller.

As described above, the command to replace the offset prevention liquid coating device is to input the signal from the sensor to the control device of the image forming device and output the command to the control panel, and also to stop the operation of the device. It is also possible to use means such as.

In the fixing device of the present invention described above, it is possible to construct a new fixing device by incorporating all of the mechanisms described above. In addition to the conventional fixing device, It is also possible to incorporate one or more of the mechanisms of the present invention to form a device with good fixing efficiency.

Further, the fixing device of the present invention can be easily applied to a device such as an electronic copying machine using a xerographic system, a laser printer, and the like, and can also be applied to an image forming device generally using a similar process. Is possible.

(Advantages of the Invention) Since the roll-type fixing device of the present invention has the above-described configuration, by setting a large paper conveyance interval when passing a small-sized paper to the fixing device, It is possible to prevent the temperature of the heating roller from largely changing locally, and to prevent uneven fixing or the like when fixing a large-sized sheet thereafter. Therefore, when the fixing device of the present invention is used in combination with a means for controlling the paper conveyance interval, the temperature distribution at the nip portion of the paper can be easily equalized. It is possible to make a copy in good condition.

Further, in the present invention, when the heat lamp supporting mechanism is provided, the fixing means of the heat lamp can be simplified, and the heat lamp can be easily positioned and maintained. Further, as described above, the roll-type fixing device according to the present invention is configured so that each mechanism of the fixing device is configured so that the heat-generating lamp can be satisfactorily fixed and other functions can be expanded. As a result, it can be easily incorporated into a conventional general electronic copying machine or the like.

[Brief description of drawings]

FIG. 1 is a sectional view of the fixing device of the present invention, FIG. 2 is a sectional plan view of the heating roller supporting mechanism of FIG. 1, FIG. 3 is a side view of the cap support, and FIG. 3a is a front view thereof. Fig. 4 is an explanatory view showing the position of the guide plate when fixing plain paper, Fig. 4a is an explanatory view of the state of the guide plate in the case of thick paper, Fig. 5 is a front view of the guide plate, and Fig. 5a is a guide. FIG. 5b is a side view showing the relationship between the plate and the swing mechanism, FIG. 5b is an explanatory view of the relationship between the lever and the sensor, FIG. 6 is an explanatory view of the fixing device provided with an offset preventing liquid applying device, and FIG. FIG. 8 is an explanatory view showing the structure of the liquid coating device, FIG. 8 is an explanatory view of the detecting means, FIG. 9 is an explanatory view of a paper sensor provided in the paper conveyance path, and FIG. 10 is a temperature when adjusting the paper conveyance interval. Fig. 11 is a graph showing the state of distribution, and Fig. 11 is an explanatory view of a fixing device using a plurality of heating lamps on a conventional heating roller, Fig. 1 2 is a graph explaining the temperature distribution in the case of FIG. 11, FIG. 13 is a side view showing the configuration of a general image forming apparatus, FIG. 14 is a sectional view of a conventional fixing device, and FIG. FIG. 4 is an explanatory view of a conventional heating lamp supporting system. Reference numeral 1 in the figure: fixing device, 4 ... upper cover, 5 ... heat insulating cover,
6 ... hanging part, 10 ... pressure roller, 11 ... pipe, 12 ...
… Rubber layer, 20 …… heating roller, 21 …… pipe, 25 …… heat lamp, 29 ・ 29a …… paper sensor, 30 …… cap support, 31 …… main body, 33 …… projection, 35 …… cover Member, 36/37 …… side cap, 38/39 …… Cover member, 40
…… Guide plate, 42 …… Cam, 45/46 …… Sensor, 50…
... offset prevention liquid application device, 51 ... web, 54 ... ground, 56 ... terminal, 60 ... photoconductor drum.

Claims (1)

[Scope of utility model registration request] 1. An apparatus for fixing a paper carrying an unfixed toner image by passing through a nip portion of a heating roller and a pressure roller and heating and pressing between the rollers to fix the paper. A heating lamp is provided so as to penetrate through the central portion, a plurality of paper sensors are arranged in the paper transport path in the upstream portion of the fixing device, and one of the paper sensors is used for detecting paper of a standard size or smaller. It is used as a paper sensor, and when a small size paper is detected by the paper sensor, the paper conveyance interval is set to be large and the heat distribution of the rollers can be averaged. The roll-type fixing device according to claim 1.