JP2714201B2 - Fixing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fixing device that heats and fixes a toner image on a recording material.

(Background technology)

As a method for fixing a toner image on a recording material, a heat roller fixing method is widely known.
No. 313182 proposed a new fixing device which solved the problem of the heat roller fixing method.

In this fixing device, a toner image is heated and pressure-fixed using a fixedly supported heating element having a low heat capacity, a film sliding on the heating element, and a pressure roller.

[Problems to be solved by the invention]

However, in such a fixed device using a film that slides on the heating element, the sliding of the film is a major factor in the load of driving the film.

In particular, in a configuration in which a predetermined pressure is applied to the sliding portion by a pressing roller or the like, the sliding of the film may reach a large part of the load for driving the film.

The sliding load of the film, that is, the frictional resistance between the heating element and the film increases at low temperatures.

This tendency becomes very large when lubricating oil is applied between the heating element and the film.

For this reason, there arises a problem that a high-output motor is required in spite of applying the lubricating oil, and that power consumption is increased.

Further, when the temperature is lower, the drive gear train may be damaged, such as gear skipping.

[Means to solve the problem]

In order to solve the above problems, the present invention is a fixed heating element, a film that slides on one surface with the heating element and the other surface moves together with the recording material bearing the unfixed image,
A fixing device that includes a driving unit that drives the film and a temperature detection unit that detects a temperature of the heating body, and that fixes an unfixed image on a recording material by heat from the heating body via the film. A lubricant is interposed between the heating element and the film, and when the temperature detected by the temperature detecting means is equal to or higher than a predetermined temperature, the driving means starts driving the film. Is what you do.

The invention of the present application also provides a fixed heating element having a heating element that generates heat by energization, and one surface slides with the heating element and the other surface moves together with the recording material bearing the unfixed image. A fixing device for fixing an unfixed image on a recording material by heat from the heating element through the film, comprising: a film; and a driving unit for driving the film. Has a lubricant interposed,
The drive means starts driving the film after the energization of the heating element is started.

(Example of the invention)

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

First, a schematic structure of an image forming apparatus using a fixing device according to an embodiment of the present invention will be described with reference to FIG. 2. Reference numeral 1 denotes a document placing table made of a transparent member such as glass, which reciprocates in an arrow a direction. Scan the original. A short-focus small-diameter imaging element array 2 is disposed immediately below the document table, and an image of the document placed on the document table is illuminated by an illumination lamp 3, and a reflected light image is formed on the photosensitive drum by the array 2. 4 is subjected to slit exposure. This photosensitive drum rotates in the direction of arrow b. Reference numeral 5 denotes a charger, for example, a photosensitive drum 4 coated with a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer.
The surface is uniformly charged. On the drum 4 uniformly charged by the charger 5, an electrostatic image subjected to image exposure by the element array 2 is formed. The electrostatic latent image is visualized by a developing device 6 using a toner made of a resin or the like that softens and melts when heated. On the other hand, a sheet P, which is a recording material stored in the cassette S, is pressed against the feed roller 7 and the image on the photosensitive drum 4 in the vertical direction at a timing synchronized with the image, and is rotated by a pair of transport rollers. 8 feeds onto the drum 4. Then, the toner image formed on the photosensitive drum 4 is transferred onto the sheet P by the transfer discharger 9. Thereafter, the sheet P separated from the drum 4 by a known separating unit is guided to a fixing device 11 by a conveyance guide 10 and subjected to a heat fixing process.
Exhausted on 12. After the transfer of the toner image, the drum 4
The upper distilled toner is removed by the cleaner 13.

FIG. 3A is an enlarged view of the fixing device 11 of the present embodiment. Reference numeral 14 denotes a low-heat-capacity linear heating element fixedly supported by the apparatus.As an example, a resistance material 16 serving as a heating layer is applied to a 1.0 mm-wide alumina substrate 15 having a thickness of 1.0 mm, a width of 10 mm, and a length of 240 mm. It is energized from both ends in the longitudinal direction. Fluorine-based lubricating grease is applied as a lubricant to the sliding surface of the heating element with the film. Energization is DC100V cycle 20msec
A pulse corresponding to a desired temperature and energy release amount controlled by a temperature detecting element 17 such as a thermistor is given by changing the pulse width. The approximate pulse width is 0.5 msec to 5 msec. The fixing film 18 moves in the direction of the arrow in FIG. An example of this fixing film is thickness 20
μm heat-resistant film, for example, polyimide, polyetherimide, PES, PFA, at least PTFE, PAF on the image contact surface side
This is an endless film in which a conductive material is added to a fluorine resin such as that described above and a release layer is coated at 10 μm. Generally, total thickness 100
μ, preferably less than 40 μ, and the film drive moves without wrinkles in the direction of the arrow due to the drive and tension by the drive roller 19 and the driven roller 20.

Reference numeral 21 denotes a pressure roller having a rubber elastic layer of silicon rubber or the like with good releasability, which presses the heating element via a screen at a total pressure of 4 to 7 kg, and rotates by pressing against the film.

The unfixed toner T on the transfer material P is guided to the fixing unit by the entrance guide 22, and a fixed image is obtained by the above-described heating.

The above is described with reference to the endless belt, but FIG. 3 (b)
As described above, the fixing film may be an edged film.

The image forming apparatus to which the fixing device of the present invention is applied is applicable to all apparatuses that form an image using a toner, such as a copying machine, a printer, and a fax.

Further, the present invention can be applied to clarification and fixing of a visible image by a method of forming an image by applying light, heat or pressure to a microcapsule included in a recording material or a transfer film to form an image. .

Next, the control operation of the image forming apparatus shown in FIG. 2 will be described in detail.

FIG. 1 is a block diagram of a control section of the image forming apparatus shown in FIG.

Reference numeral 101 denotes a control circuit composed of a microcomputer or the like, 102 denotes a ROM in which control software and control data performed by the control circuit are stored, and 103 denotes a writable memory (RAM) used for control. Sensor signals are input to input ports PO, PU, and EX of the control circuit, and a document table position sensor 104, a paper feed sensor 105, and a paper discharge sensor 106 are connected to each of them. Each sensor is composed of a photointerrupter and a shield, and when a shield is detected, each of the input ports PO, PU, EX goes to high level 1.

 M is a drive output signal of the motor 107.

The main motor is connected to the fixing film drive,
The film is driven by the drive of the main motor. An operation unit 110 is connected to the control circuit 101, and performs key input and display by an operator.

 One example of this operation is shown in FIG.

 119 is a power lamp which is always lit when the power is turned on.

Reference numeral 118 denotes a JAM lamp, and 117 denotes a 7-segment display unit for displaying an error display JAM together with the JAM lamp, or for 7-segment display using the operation keys. 113-116
Are operation keys, 113 is a copy key, 114 is a clear key, 115 is a plus key, and 116 is an AE key. Also, 120 is A
Display the AE operation with the E lamp.

In FIG. 1, reference numeral 16 denotes a fixing heater, 17 denotes a heater temperature detecting element such as a thermistor, and 109 denotes a circuit for energizing the heater. Reference numeral 108 denotes a fan for exhaust heat exhaust.

Next, in FIG. 5 and subsequent figures, the control circuit 10
The control operation of 1 will be described.

The control of the control circuit 101 will be described with reference to the flowcharts of FIG. Fig. 5 shows when the copy key is ON,
This is a subroutine called when an image forming signal is input and an image forming operation is started. In this subroutine, first, a preheating operation of the fluorescent lamp is started for lighting the fluorescent lamp. Ti is a heating element temperature detected by the thermistor 17 after the copy key is turned on and before the energization of the heating layer 16 is started.
It is determined whether the temperature is higher than 0 ° C., and when it is low, the set temperature of the heater is set to, for example, 200 ° C., and when it is high, it is set to, for example, 185 ° C. The power supply to the heating layer 16 is controlled via the power supply 109 so that the detected temperature of the thermistor 17 becomes the above-mentioned set temperature.

If Ti is higher than a second predetermined temperature, for example, 60 ° C., the main motor is driven simultaneously with the start of energization to the heater.
Also, when the temperature is lower than 60 ° C, after the heater is energized,
After a predetermined time, for example, after 0.25 seconds (201), the main motor is driven.

The heating element temperature is reduced to the second by applying the current for 0.25 seconds.
The temperature is raised to 60 ° C or more, which is the set temperature of

In this way, when the heating element is cooled, the motor is driven and the motor is driven to slide the film. By heating the heating element surface, the frictional force between the fixedly supported heating element surface and the fixing film 18 is increased. Can be lowered. As a result, the starting torque of the fixing device is reduced, and the load torque of the main motor can be reduced.

In particular, when lubricating oil (fluorine-based lubricating grease is used in this embodiment) is interposed between the heating element used in the fixed state at the time of fixing and the fixing film as in this embodiment. The difference between the load torque at normal temperature and the load torque at the start of heating is large. According to the experiment, it is 5.2 kg · cm at 20 ° C, 3.0 kg · cm at 100 ° C, and 1.8 kg · cm at 180 ° C. This is because, as a general property of greases, the viscosity decreases as the temperature increases.

As described above, the starting torque when the main motor is driven 0.25 seconds after the start of energization of the heater is 2.5 kgcm, which is compared to the starting torque of 4.0 kgcm when the energization of the heater and the driving of the motor are started simultaneously. About 40% reduction has been achieved.

The value of Ti is stored in the RAM 103. Then, the fan is driven to discharge heat from the image forming apparatus with the energization of the heating element.

After a predetermined fluorescent lamp preheating time elapses after SUB1, the fluorescent lamp is turned on and the copying operation starts. FIG. 6 shows a subroutine called when the fluorescent lamp is turned on.

In SUB2, the fan that has been driven for exhaust heat is stopped first, and the fluorescent lamp is turned on. This stops the flow of the wind around the fluorescent lamp by stopping the fan, and helps the fluorescent lamp to start lighting in cold weather. Next, by comparing the Ti value stored in the RAM 103 with the current heating element temperature T _FLON , it is determined whether there is an abnormality in the thermistor or the heating element (20).
2). At this time, if Ti is higher than the third predetermined temperature, for example, 150 ° C., the process of 202 is not performed (203). Like this
Therefore, even if the difference between the third set temperature and Ti is small in a normal state, it is possible to prevent an erroneous judgment from being made. When there is no abnormality in the thermistor or the heater, the platen is backed by the platen driving solenoid, and the platen is stopped at the start position by the platen position sensor 104. When judging abnormalities,
Stop the copying operation and proceed to the 7-segment or JAM
Display on the lamp. Further, after the light amount of the fluorescent lamp has sufficiently risen, the fan is driven again at a predetermined time, for example, at a time when a high voltage is output.

After the platen stops at the start position, an image is formed according to the above-described copying process.

Copying process is completed, after a ₀ predetermined time t stop power supply to the heater after detecting that the sheet P has left the fixing device in the sheet discharge sensor 106, to stop the motor, for example after 1 second, it ends the copying operation (See FIG. 7). Fig. 7 SU
In B3, t ₁ is the timer value for detecting discharge dwell JAM, a time determined by the body size and the sheet conveying speed.

 The above operation is shown in the timing chart of FIG.

Further, in this embodiment, the drive start timing of the fixing film is switched by Ti, but the drive of the film may be started after a predetermined time has elapsed from the start of energization to the heating element regardless of Ti.

 Next, still another embodiment of the present invention will be described.

In this embodiment, the film drive is started when the temperature of the heating body reaches a predetermined temperature.

FIG. 9 shows a subroutine of the control circuit 101 which is called when the copy button is turned ON, showing the embodiment.

This subroutine first starts a known preheating operation for lighting the fluorescent lamp, as in the case of FIG. Thereafter, power is applied to the heat generating layer 16. When the heating element temperature T detects a predetermined temperature T equal to or higher than a predetermined temperature, for example, 100 ° C. or more by the thermistor attached to the heating element (204), the motor driving is started. The application of electric power to the heat generating layer is controlled so as to reach a set temperature, for example, 185 ° C. Further, as described in the first embodiment, the above temperature may be switched according to the heater temperature Ti at the time of copying ON (not shown).

 Next, a third embodiment of the present invention will be described.

In this embodiment, the drive of the film is started when the temperature of the heating element reaches a predetermined temperature or when one of a lapse of a predetermined time from the start of energization of the heating element is satisfied.

 FIG. 10 is a flowchart showing this embodiment.

FIG. 10 shows a subroutine called at the time of copy ON.
As in the first and second embodiments, first, a known preheating operation for lighting the fluorescent lamp is started. Then the heating layer
At 16, power is applied so as to reach a predetermined set temperature. Either the heating element temperature T detects a predetermined temperature, for example, 100 ° C. or higher by the thermistor attached to the heating element (205), or a predetermined time of 0.25 seconds elapses after the heater is turned on (206). Then, driving of the main motor is started. By observing both the elapsed time and the temperature in this manner, it is possible to prevent the fixing film from being heated while the fixing film is stopped for a long time, such as when the line of the thermistor is abnormal, thereby preventing the film from being damaged. Further, as described in the first embodiment, the set temperature may be switched according to the heater temperature Ti at the time of copying ON (not shown).

〔The invention's effect〕

As described above, by starting the film drive in a state where the heating element is at or above the predetermined temperature, the starting torque of the fixing device can be greatly reduced, and a low-output motor can be used. Therefore, even at a lower temperature, it is possible to prevent the drive gear train from being damaged and the gear from jumping.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a sectional view of an image forming apparatus to which the fixing device of the embodiment of the present invention is applied, and FIG. FIG. 3B is a cross-sectional view of a fixing device according to another embodiment of the present invention, FIG. 4 is an enlarged view showing an operation unit of the image forming apparatus shown in FIG. 2, and FIG. To FIG. 7 are flow charts showing the control operation of the embodiment of the present invention, FIG. 8 is a timing chart of the embodiment of the present invention, and FIGS. 9 and 10 are flow charts showing another embodiment of the present invention. It is a chart. 14: Heating element 16: Heater 17: Thermistor 18: Fixing film 101: Control circuit 107: Drive motor 109: Fixing power supply

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Mori 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Kuroki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-63-313182 (JP, A) JP-A-2-77776 (JP, A) JP-A-59-68766 (JP, A)

Claims (2)

(57) [Claims] 1. A fixed heating member, a film having one surface sliding with the heating member and the other surface moving together with a recording material bearing an unfixed image, and a driving device for driving the film Means, and a temperature detection means for detecting the temperature of the heating element, a fixing device for fixing an unfixed image on a recording material by heat from the heating element through the film, wherein the heating element A fixing device, wherein a lubricant is interposed between the films, and when the temperature detected by the temperature detecting means is equal to or higher than a predetermined temperature, the driving means starts driving the film. 2. A fixed heating element having a heating element that generates heat by energization, and one surface slides on the heating element and the other surface moves together with a recording material bearing an unfixed image. Having a film and driving means for driving the film,
In a fixing device for fixing an unfixed image on a recording material by heat from the heating element via the film, a lubricant is interposed between the heating element and the film, and a current is supplied to the heating element. The fixing device, wherein after the start, the driving unit starts driving the film.