JPH0227384A - Fusing device - Google Patents

Abstract

PURPOSE:To stably fix an image without being influenced by various factors by providing a control means MPU, a buffer, a power control means, an AC power source, an A/D converter, a counter and a controller. CONSTITUTION:In a power control means 33, an LED 33a receives a command of an MPU through a buffer 32, turns on triac 33b and executes a feed to a heater 4 of a fixing device 24. An A/D converter 35 detects a variation of an ambient temperature of the fixing device 24 by a thermistor 3, and informs it to the MPU. A buffer 38 transfers various commands to a driving source of each part of an image forming device, and a buffer 39 conveys detecting signals from a feed paper sensor and other various sensors to the MPU. A counter 41 gives a counting value 44 of a pulse 43 for showing a rotation stop time of the fixing device 24 to the MPU, and reset by a signal 42. A controller 45 generates an image forming command to the MPU. The MPU corrects a target reference temperature of the fixing device 24 by the counting value 44, controls the power control means 33, controls each driving device through the buffer 38, when a correction value and a detection value of a thermistor 3 have coincided, and allows said fixing device to execute a stable fixation.

Description

[Detailed Description of the Invention] L! BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a fixing device, and more particularly to a fixing device applied to an image forming apparatus such as an electrophotographic copying device employing the 2-Carlson electrophotographic process.

[As is well known, this type of fixing device uses a recording material 6 on which a visible image has been transferred, which is guided in the direction of arrow B via a guide plate 5, as shown in FIG. , a fixing roller L, and a pressure roller 2 whose outer circumferential surface is disposed so as to be able to come into contact with the outer circumferential surface of the fixing roller 1, and the image is fixed by the pair of rollers. This is how it is.

The fixing roller 1 is configured to be rotatable clockwise in FIG. 6 (that is, clockwise in FIG. 6) by a fixing roller drive motor (not shown), and the fixing roller 1 is configured to be rotatable clockwise in FIG. A substantially cylindrical heater 4 is incorporated in order to heat the cylinder. The heater 4 described above is driven by power supplied from a heater drive power source (not shown). In FIG. 6, a thermistor 3 is placed above the fixing roller l in close proximity to the outer circumferential surface of the fixing roller l so that the temperature of the outer circumferential surface of the fixing roller 1 can be detected.
is installed. On the other hand, the pressure roller 2 moves the fixing roller 1 counterclockwise in FIG.
It is configured to be rotatable according to the rotation of the fixing roller 1, and works with the fixing roller 1 to fix the visible image on the recording material 6 provided via the guide plate 5 onto the recording material 6. It has become. The guide plate 5 is arranged between a portion of the recording material 6 on the upstream side in the conveying direction and the recording material 6 so as to receive the recording material 6 conveyed by a conveyance means of an image forming apparatus (not shown) and guide it smoothly to the pair of rollers. The portions on the downstream side in the conveyance direction are respectively bent diagonally downward in FIG.

The mode of control for maintaining the temperature value of the outer circumferential surface of the fixing roller 1 at a predetermined temperature is, for example, a control means such as a microcombination controller reading a temperature detection signal output from the thermistor 3 and controlling the temperature value. When the means recognizes that the temperature detection signal is higher than a preset outer circumferential surface temperature reference value of the fixing roller 1, the means cuts off the power supply to the heater 3 from the heater drive power source, and also detects the temperature detection signal. When it is recognized that the temperature is lower than the temperature reference value, power supply to the heater 3 from the heater drive power source is started or continued.

Generally, the temperature of the fixing roller 1 of the fixing device is controlled more when the fixing roller 1 is rotating than when it is not rotating, that is, when the image of the developed image on the supplied recording material 6 is being fixed. The temperature is controlled so that the temperature is higher when

However, conventional temperature control in the fixing roller 1 of the above-described fixing device has been carried out in a manner as shown in FIG. That is, in FIG. 7, from the time point 0 when the image forming apparatus is in the standby state to the time point to shown on the horizontal axis 1-, the temperature of the outer circumferential surface of the fixing roller l is To'C. By controlling the power supply of the heater drive power source so that When a drive command signal to start image formation is output from the controller, the power supply of the heater drive power source is controlled so that the temperature of the outer circumferential surface of the fixing roller l reaches the target temperature value of 11° C. immediately. Then, when the outer circumferential surface temperature reaches the T1°C by the temperature control (i.e., point 1+ on the horizontal axis), the rotation of the fixing roller 1 is started and the recording material 6 is supplied to the pair of rollers. That's what I used to do. However, as the fixing roller l starts rotating, the pressure roller 2 naturally also starts rotating. The lower low-temperature portion comes into contact with the outer circumferential surface of the fixing roller 1, and the outer circumferential surface temperature of the fixing roller 1 changes from 11° C. to a point t1 on the horizontal axis as shown by the dotted chain line ■ in FIG. The value of ΔT°C, which decreases by up to 61°C in the time from However, it is approximately 0°C to 20°C, and the time 1.-12 required to return to the original temperature value T+"O may be 10 seconds or more. Therefore, the horizontal axis in Figure 7 If the recording material 6 is supplied to the pair of rollers between point 1 and point tz above, 1. For example, on the leading edge side of the recording material 6, the toner forming the visible image is on the recording material. Even if the fixation on the recording material 6 is performed well, there are problems such as a high degree of fixation failure on the trailing edge side of the recording material 6, and images with high printing density on the recording material 6. In the case of patterns, there has been a problem in that the above-mentioned tendency is particularly noticeable.

The present invention was devised in order to improve the above-mentioned conventional problems, and its purpose is to improve the thermal conductivity of the fixing roller and pressure roller, including the atmospheric temperature of the fixing device. To provide a fixing device capable of successfully fixing a visible image formed on a recording material to the recording material regardless of various factors such as shape and print density on the recording material. .

The above-mentioned object for fixing images is achieved by a fixing device according to the present invention. In summary, the present invention provides a fixing rotary body having a heating means, and a recording material whose outer circumferential portion is disposed so as to be able to come into contact with the outer circumferential portion of the fixing rotary body and which is changed in cooperation with the fixing rotary body. a pressure rotating body for fixing a visible image; a heating means driving means for driving the heating means; a fixing rotary body driving means for driving the fixing rotary body; A temperature detecting means for detecting a temperature, a counting means for counting a stop time of the fixing rotor, and a target temperature value for controlling an outer circumferential temperature of the fixing rotor based on the count from the counting means. , by reading an output signal from the temperature detecting means and controlling the heating means driving means, after the outer peripheral temperature of the fixing rotary body reaches a target temperature value, the fixing rotary body driving means and the heating means driving means are controlled. The fixing device is characterized in that it includes a control means for controlling the timing of supply to both rotating bodies.

1 actual example An embodiment of the present invention will be described below with reference to one drawing.

FIG. 2 shows an image forming apparatus to which a fixing device according to an embodiment of the present invention is applied. In other words, in FIG. Approximately at the center of the photosensitive drum 1, which is a carrier of the
6, a cleaner section 20, a high-voltage charger 17. A developing device 18 and a transfer charger 19 are respectively provided, and a folding mirror 14 is provided above the photosensitive drum 1B between the -order high voltage charger 17 and the developing device 18. A fixing device 24 according to an embodiment of the present invention is disposed on the left side of the above-mentioned photoconductor drum 16 and various devices disposed around it in FIG. There is a paper ejection roller 25 on the left side of 24.
and a paper output tray 26 protruding from the outside of the apparatus main body lO.
are arranged respectively. On the other hand, on the right side of the apparatus 10 in FIG. A paper roller 22 is provided. A developing device 18 on the lower side of the recording material moving direction of the paper feed roller z2
A registration roller 23 is provided at a location adjacent to. Above the area from the paper feed roller 22 to the registration roller 23 in the apparatus main body 10 described above, there are a laser emitting terminal 13, a scanner motor 12, and so on. Suyana mirror rotated at a constant speed by the scanner motor 12
(that is, a polygon mirror) 11, etc. are provided.

A brief description of each of the above-mentioned configurations is as follows. That is, the laser emitting element 13 is constituted by, for example, a semiconductor laser, and emits a laser beam 15 that is on/off modulated in accordance with a drive command signal output from a controller 45 shown in FIG. ing. The scanner mirror 11 receives the laser beam 15 emitted from the laser light emitting element 13, deflects it, and supplies it to the folding mirror 14. The folding mirror 14 receives the laser beam 15 deflected by the scanner mirror 11 and forms an image on a region defined by the -order high voltage charger 17 and the developer 18 on the photoreceptor drum 16. It has become. The -order high-voltage charger 17 is configured to charge the outer peripheral surface of the photosensitive drum 16 in a substantially -like manner before being irradiated with the laser beam 15. The developing device 18 develops the electrostatic latent image formed on the outer circumferential surface of the photoreceptor drum 16 by the irradiation of the laser beam 15 with a predetermined developer, and converts the electrostatic latent image into a visible image. It has become. The transfer charger 19 is used to transfer the developed image formed on the photoreceptor drum 16 by the developer 18 onto the conveyed recording material, which is a sheet-like recording medium, by high-pressure corona discharge. The reliner section 20 scrapes and collects the developer remaining on the photoreceptor drum 16. Paper feed roller 2
Reference numeral 2 is a device that, when driven, feeds the recording material stored in the paper feed cassette 21 to the position where the registration rollers 23 are arranged. The registration roller 23 is configured to receive the recording material supplied via the paper feed roller 22 and send it out toward the photosensitive drum 16 at a predetermined timing. The fixing device 24 heats the recording material that has undergone the above-described transfer process through the cooperation of a fixing rotor, that is, the constant B roller 1, and a pressure rotor, that is, the pressure roller 2.
By applying pressure, the visible image is fixed on the recording material. Note that the details of the configuration of the fixing device 24 have already been explained with reference to FIG. 6, so a description thereof will be omitted. The paper ejection roller 25 is configured to receive the recording material applied via the fixing device 24 and eject it to the paper ejection tray 26 .

FIG. 1 shows a control system of a fixing device according to an embodiment of the present invention. As is clear with reference to FIG.
(i.e., a microprocessing unit, the same applies hereinafter) 31, a buffer 32, a power control means 33, an AC power supply 34, an A/D converter 35. Bar / 7 y 38
-1 to 38-m, buffers 39-1 to 40-n, counting means, that is, a counter 41, a controller 45, and the like. The bar 2 fa 32 once receives a heater on/off drive command signal output from the MPU 31 and outputs it to the power control means 33. The power control means 33 drives the LED 3 according to an on/off drive command signal given via the buffer 32.
3a and an optical triac 33b driven by the light emitted from the LED 33a, and when the optical triac 33b becomes conductive by the light emitted from the LED 33a, the heating means driving means, that is, the AC power source 34 Electric power is supplied to the heating means, that is, the heater 4. The A/D converter 35 is connected to a DC power supply V
is connected to a voltage dividing circuit that divides the pressure by a resistor 37 and the resistance value of the thermistor 3 that detects the temperature of the outer circumference of the fixing roller 1, and as the temperature of the outer circumference of the fixing roller 1 changes. A voltage signal across the thermistor 3 whose resistance value is variable is converted into an 8-bit digital signal 36 and output to the MPU 31. The buffers 38-1 to 38-m serve as drive sources for driving each part of the image forming apparatus shown in FIG.

After once receiving various command signals outputted from the MPU 31, they are outputted respectively. Buffers 39-1 to 40-n
Once receives detection signals output from various sensors, such as a sensor that detects the presence or absence of recording material in the paper feed cassette 21 and a sensor that detects the size of the recording material in the paper feed cassette 21. After that, these various detection signals are sent to MPU31.
This is what is output to. The counter 41 counts a pulse signal 43 indicating the rotation stop time of the fixing roller l outputted from the MPU 31 at a rate of 1 pulse/l sec, and calculates count value data (8-bit data) of the pulse signal 43.
44 is output to the MPU 31.

The count contents of the counter 41 are configured to be reset by a counter reset signal 42 output from the MPU 31. The controller 45 is connected to the MPU 31 via an interface signal line 46.

By outputting an image forming command signal to the MPU 31, the image forming apparatus shown in FIG. 2 is caused to perform an image forming operation.

The MPU 31 described above includes a CPU that controls the driving of the entire image forming apparatus shown in FIG. The control data such as the above is constructed of a RAM or the like in which control data can be freely written/read. MPU
31 reads the count value data 44 of the pulse signal 43 output from the counter 41, and determines a target reference temperature value for controlling the outer circumferential temperature of the fixing roller l, which is preset according to the count value data 44. The 0MPU31 to be corrected is
A temperature detection signal output from the thermistor 3 is read through the A/D converter 35, and a drive command signal is sent through the buffer 32 so that the temperature detection signal matches the correction value of the target reference temperature value. By controlling the drive of the power control means 33, the amount of heating of the heater 4 to the fixing roller l is adjusted. When the MPU 31 recognizes that the temperature detection signal given from the thermistor 3 via the A/D converter 35 matches the correction value of the target reference temperature value, it selects one of the buffers 38-1 to 38-m. The fixing rotor driving means, that is, the fixing roller drive motor, the registration roller 23 drive motor, or the paper feed roller 22
It is configured to control the drive of a drive motor and the like.

Next, the control operation of the control system of the fixing device described above will be explained mainly with reference to the flowchart shown in FIG. When the operator turns on the driving power of the image forming apparatus, both the controller 45 and the MPU 31 start driving. When the MPU 31 recognizes that a predetermined image forming command signal has been output from the controller 45 via the interface signal line 46 (step 101), the process proceeds to step 102. The count value data (Tcnt) 44 output from the counter 41 is read (step 102), and the read data T c n L is 5.
Check whether it is less than sec (step 103)
, When it is recognized in step 103 that the data Tent is less than 5 seconds (including Osec), the target temperature value for controlling the temperature of the outer circumferential portion of the fixing roller l is set on the vertical axis T+('Ill:) in FIG. In step 104), the temperature at the outer periphery of the fixing roller l is controlled by controlling the power supply from the AC power supply 34 to the heater 3 based on the temperature detection signal output from the thermistor 3. The temperature of the heater is controlled as shown by the solid line in the W44 figure, and the temperature of the heater is controlled so that the temperature becomes T1°C (step 108). At step 108, it is recognized that the temperature of the outer circumferential portion of the fixing roller l has approximately coincided with 11°C. Then, paper feed roller 2
2 drive motor, registration roller 23 drive motor, etc., and also drives the fixing roller L drive motor to start supplying the recording material onto which the visible image has been transferred to the fixing device 24 (Step 109); counter 41
The counter 41 is reset by outputting a counter reset signal 42 to the counter (step 110).

At step 103, the read data Tcnt is 5.
When it is determined that the data is not less than sec, the data Ten
Step 1: Check whether t is less than 30 seconds.
05), in step 105, the data Tcnt is 3.
When it is recognized that it is less than 0 sec, the target temperature value for controlling the temperature of the outer circumference of the fixing roller l is set on the vertical axis TI+ in FIG.
α.

(°C) (that is, the value obtained by correcting the target reference temperature value TI°C by the value of α1) (step 10B), and the power supply from the AC power supply 34 to the heater 4 is started based on the temperature detection signal output from the thermistor 3. By controlling, the temperature of the outer peripheral part of the fixing roller 1 is varied as shown by the solid line and broken line in FIG. The same is true.

At step 105, the data Tcnt is set to 30 seconds.
If it is recognized that the temperature is not less than the target temperature value for controlling the outer peripheral temperature of the fixing roller l, $4 Figure vertical axis T1+αz (
'O) (i.e., the value obtained by correcting the target standard temperature value ℃ by the value of αZ). Step 107) By controlling the power supply, the temperature of the outer circumferential portion of the fixing roller l is varied as shown in the solid line to broken line to one-dot chain line in FIG.
O) (step 108), step 109
The rest is the same as above.

When it is recognized in step 101 that the image forming command signal is not output from the controller 45, it is determined whether or not the fixing roller 1 drive motor has stopped driving. When it is recognized that the system is stopped, the process moves to step 112. The driving stop time of the fixing roller l drive motor is 1 s.
If it is determined that it is equal to or higher than ec (step 112), a pulse signal 43 is output to the counter 41 (step 113). Here, the target temperature reference value and the corrected target temperature Value T℃,'rI+a1''o
, T + αz℃, there is a relationship between T, (T, + α, < T,
It is clear that the relationship +α2 holds true. The values α1 and αB for correcting the target temperature reference value T1° C. may be any value as long as the above-mentioned relationship is established.

In the embodiment according to the present invention described above, the preset target reference temperature value T1°C is corrected according to the value of the count value data (Tcnt) read in step 102, and the temperature of the outer circumference of the fixing roller 1 is adjusted. After the temperature reaches the correction value and the supply of the recording material to the fixing device 24 is started (step 109), the counter 41 is reset (step 110). For example, when executing an image forming process in which recording material is continuously supplied to the fixing device 24, the target reference temperature value T+'O is first set to T1+αZ"0. In this embodiment, the temperature may be controlled by setting the temperature to 11° C., then gradually decreasing the set value to perform temperature control, and finally setting the set value to 11°C. The target reference temperature value for controlling the temperature of the outer circumference of the fixing roller I is corrected according to the rotation stop time of the fixing roller I. For example, as shown in FIG. A method may also be considered in which the power supply to the heater 4 is controlled so that the rate of change in temperature at the outer circumference of the heater 4 is varied.

That is, in the flowchart shown in FIG. 3,
In step 104, step 106, and step 107, target temperature values are set, and the rate of temperature rise of the outer peripheral portion of the fixing roller l by the heater 4 is also set.

For example, in step 104, the temperature increase rate is set to 5°C/s.
In step 106, the temperature increase rate is set to 7'C/c.
In step 107, the temperature and rate of increase are set to 10.
℃/see, it is possible to supply the recording material at a substantially constant timing, regardless of the length of time during which the rotation of the fixing roller l of the fixing device 24 is stopped, as shown in FIG. became. Step 104. Step 106.
When setting the target temperature value and the temperature increase rate in step 107, a plurality of heaters 4 are provided, each heater 4 is made to correspond to the respective temperature increase rate, and the rotation of the fixing roller 1 is adjusted. The driving of each heater 4 may be selected according to the stop time Tcnt. In one embodiment according to the present invention, a counter 41 is provided as a means for counting the rotation stop time Tcnt of the fixing roller 1. However, the counting means according to the present invention is not limited to the counter 41 described above, but, for example, the function of the counter 41 may be implemented as software in the RAM included in the MPU 31.

Although the present invention is particularly suitably applied to laser printers among image forming apparatuses, the scope of application is not limited to laser printers only, and can be applied to LED array printers using LED arrays and liquid crystal display printers. Naturally, it can also be applied to printers.

Main jL mouth JLII.

As explained above, according to the present invention, regardless of various factors such as the ambient temperature of the fixing device, the thermal conductivity of the fixing rotor and the pressure rotor, the shape, and the printing density on the recording material, First, it is possible to provide a fixing device that can satisfactorily fix a visible image formed on a recording material to the recording material.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a control system of a fixing device according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing the overall configuration of an image forming apparatus to which a fixing device according to an embodiment of the present invention is suitably applied. FIG. 3 is a flowchart showing the control operation of the control system of the fixing device shown in FIG. 1. 4 and 5 are explanatory diagrams of the operation of the control system of the constant R device according to one embodiment of the present invention. FIG. 6 is a perspective view showing the general structure of a fixing device suitably applied to each image forming bag such as an electrophotographic copying device. FIG. 7 is an explanatory diagram of the operation of the control system of the fixing device according to the prior art. Fixing roller: Pressure roller thermistor: Heater: MPU: Power control means 2 AC power supply: Counter Fig. 4 Print command Start of paper feeding Fig. 6 Fig. 7 t. time

Claims (1)

[Claims] 1) Image fixation of a visible image on a recording material provided by a fixing rotary body having a heating means and an outer circumferential portion of which is disposed so as to be able to come into contact with the outer circumferential portion of the fixing rotary body, and provided in cooperation with the fixing rotary body. a heating means driving means for driving the heating means; a fixing rotary body driving means for driving the fixing rotary body; and a temperature detection means for detecting the temperature of an outer peripheral portion of the fixing rotary body. , a counting means for counting the stop time of the fixing rotor, and a target temperature value for controlling the outer peripheral temperature of the fixing rotor based on the count from the counting means;
By reading an output signal from the temperature detecting means and controlling the heating means driving means, after the outer peripheral temperature of the fixing rotary body reaches a target temperature value, both the fixing rotary body driving means and the recording material are controlled. A fixing device comprising a control means for controlling timing of supply to a rotating body.