JPH0695550A - Heat fixation device - Google Patents

Abstract

PURPOSE:To shorten the warmup time of and prevent poor performance of fixation by a heat fixation device which includes a heat roller fixing apparatus to make heat fixation of a toner image on a medium and a preheater to make preheating of the medium. CONSTITUTION:A heat fixation device includes a heat roller fixing apparatus 2 to make heat fixation of toner on a medium through a medium holding a toner image, between a heat roller 21 and a pressurizing roller 22, and a preheater 20 located at the fore stage of the heat roller fixing apparatus 2 to heat the medium auxiliarily, wherein the heating of the heat roller 21 is turned off when an alarm is given, and upon resetting, the heating of the same 21 is turned on, followed by warming-up to make ready for the fixing process. Therein a control part 43 is furnished to make heating control of the heat roller 21 and preheater 20 and controls the temp. of the preheater 20 to a level higher than at normal printing in compliance with the issue of the alarm.

Description

Detailed Description of the Invention

(Table of Contents) Industrial Application Field of the Prior Art (FIG. 8) Problem to be Solved by the Invention Means for Solving the Problem (FIG. 1) Action Example (a) Description of Color Printing Apparatus (FIG. 2) To FIG. 3) (b) Description of one embodiment (FIGS. 4 to 7) (c) Description of another embodiment Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal fixing device having a thermal roller fixing device for thermally fixing a toner image on a medium and a preheater for preheating the medium.

In an image recording apparatus such as a copying machine, a printer or a facsimile apparatus, a latent image forming type recording apparatus such as an electrophotographic apparatus is used in order to record plain paper. In such an image recording apparatus, an electrostatic latent image is formed, developed, and a toner image is formed.
The image is transferred to the medium and the toner image is fixed.

A heat roller fixing device having a simple structure is used for fixing the toner image. Especially, in the case of full-color printing, the heating force of the heat roller fixing device is not sufficient for fixing and the toner is fixed. For stable fixing, it is necessary to preheat the medium.

[0005]

2. Description of the Related Art FIG. 8 is an explanatory diagram of a conventional technique. For example, in the electrophotographic apparatus, as shown in FIG. 8A, the toner image formed on the photosensitive drum 10 is transferred onto a sheet, conveyed to the heat roller fixing device 2, and then heated by a heat roller (heat roller) 21.
It is sandwiched between the backup roller (pressure roller) 22 and the toner on the paper is thermally fixed.

At this time, when the toner characteristics and the toner layers are overlapped and the toner layer becomes thick as in color printing,
It becomes difficult to fix. In this case, if the heating temperature of the heat roller 21 is raised, the color of the toner changes color. Therefore, the preheater 20 is provided in front of the heat roller fixing device 2, and the preheater 20 preheats the toner to soften it. It is sent to the roller fixing device 2 to prevent fixing failure.

By the way, when a device alarm such as a paper jam occurs, the paper may stay in the heat roller fixing device 2 and cause a burnout of the paper, and it is dangerous for a person to be inserted to remove the jam. For prevention, the heater of the heat roller fixing device 2 is turned off as shown in FIG.

At this time, in the jam processing, the backup roller 22 is retracted to remove the jammed paper. Therefore, the temperatures of the heat roller 21 and the backup roller 22 drop, and when the alarm is released and the reset is applied, the heating of the heat roller 21 is turned on and the temperature of the heat roller 21 rises.

When the temperature of the heat roller 21 reaches the set printing temperature (about 180 ° C.), the ready (Redy) signal indicating that printing is possible is raised to indicate that fixing can be performed, and the reset is performed before printing becomes possible. It takes a warm-up time from to the set printing temperature.

At this time, the temperature of the preheater 20 is 40 °
C was kept constant and was not controlled separately.

[0011]

However, the prior art has the following problems. The warm-up time until fixing becomes possible from the alarm release to the time when the heat roller 21 reaches the set printing temperature, and the warm-up time becomes long.

When the backup roller 22 retreats, the temperature of the backup roller 22 also drops, so
Even if the heat roller 21 reaches the set temperature, heat is taken by the backup roller 22 and even if fixing is possible, defective fixing occurs.

Therefore, an object of the present invention is to provide a thermal fixing device capable of reducing warm-up time and preventing fixing failure.

[0014]

FIG. 1 shows the principle of the present invention. Claim 1 of the present invention provides a heat roller 21 and a pressure roller.
The heat roller fixing device 2 for thermally fixing the toner on the medium by passing the medium holding the toner image between the heat roller fixing device 2 and the roller 22, and is provided in front of the heat roller fixing device 2 to assist the medium. In a thermal fixing device having a preheater 20 for heating, the heating of the heating roller 21 is turned off when an alarm occurs, the heating of the heating roller 21 is turned on by resetting, and after warming up, fixing is possible. A control unit 43 for controlling the heating of the heat roller 21 and the preheater 20 is provided, and the control unit 43 controls the temperature of the preheater 20 to be higher than the normal temperature in response to the occurrence of the alarm. It is characterized by

According to claim 2 of the present invention, in claim 1,
The controller 43 controls the preheater 2 when the heat roller 21 reaches a set temperature after the warm-up is completed.
It is characterized by returning the temperature of 0 to the normal temperature.

A third aspect of the present invention is characterized in that, in the first or second aspect, the control section 43 enables fixing before the heat roller 21 reaches the preset temperature due to the warm-up. .

A fourth aspect of the present invention is characterized in that, in the first, second, or third aspect, the medium holding the toner image has toner of each color transferred thereon.

[0018]

According to the first aspect of the present invention, the temperature of the preheater 20 is set higher than the normal temperature in response to the occurrence of the alarm. Therefore, even if the temperature of the heat roller 21 is equal to or lower than the set temperature, the amount of preheat to the medium is increased. Since the number can be increased, the fixing can be performed, the warm-up time can be shortened, and the fixing failure can be prevented even if the pressure roller 22 receives heat.

According to the second aspect of the present invention, when the heat roller 21 reaches the set temperature, the preheater 20 has a high preheat amount at a high temperature, and fixing failure occurs. Therefore, the temperature is returned to the normal temperature.

According to the third aspect of the present invention, by controlling the pre-heater 20, even if the temperature of the heat roller 21 is below the set temperature, the fixing can be performed. Therefore, the fixing can be performed before the set temperature is reached, and the warm-up time is increased. It will be shortened.

According to the fourth aspect of the present invention, in the case of color printing, the toners of respective colors are laminated, the thickness of the toner layer becomes thicker, and it becomes difficult to fix the toner. Therefore, by controlling the temperature of the preheater 20, the fixing is performed. It is stable and effective in reducing warm-up time.

[0022]

【Example】

(a) Description of Color Printing Device FIG. 2 is a block diagram of a color printing device according to an embodiment of the present invention, and FIG.
FIG. 1 is a configuration diagram of a main part of a color printing apparatus according to an embodiment of the present invention, showing an electrophotographic color printer.

In FIG. 2, reference numeral 1 denotes a recording section, which is composed of an electrophotographic recording mechanism of four colors (magenta, cyan, yellow, and black), which will be described later with reference to FIG. It is a fixing device and includes the above-mentioned preheater 20,
It has a heat roller 21 and a backup roller 22.

Numeral 30 is a hopper for accommodating printing continuous paper, 31 is a stacker for accommodating printed continuous paper from the heat fixing device 2, 32 is a conveyor belt, and hopper For feeding the paper from the recording unit 1 to the recording unit 1, 33 is a conveyor belt for conveying the paper from the recording unit 1 to the heat fixing device 2, and 34 is a controller for connecting the recording unit 1 and the like. It has a control circuit for controlling.

In FIG. 3, the electrophotographic recording mechanism of each color includes photosensitive drums 10a to 10d and photosensitive drums 10a to 10d.
Pre-charging devices 11a to 11d for pre-charging 10d, optical units 12a and 12b for writing an optical image of each color on the photosensitive drums 10a to 10d to form an electrostatic latent image, and electrostatics of the photosensitive drums 10a to 10d. Developing devices 13a to 13d for developing latent images with toners of respective colors, and photosensitive drums 10a to 10
transfer rollers 14a to 14 for transferring the toner image of d to the sheet
d and cleaners 15a to 15d for removing the residual toner on the photosensitive drums 10a to 10d.

Here, a pair of optical units 12a and 12b for generating light images of two colors for four colors are provided. Here, each of the developing devices 13a to 13d has a developing roller 16 that conveys the developer to the photosensitive drum and an agitating roller 17 that agitates the internal developer. For example, the developing device 13a has a black color. The developer, the developing device 13b, the cyan developer, the developing device 13c,
A magenta color developer and a yellow color developer are stored in the developing unit 13d. The photosensitive drum 10a is irradiated with a black image by the optical unit 12a, and the photosensitive drum 10b is irradiated with an optical image. The unit 12a irradiates a cyan image, the photosensitive drum 10c irradiates a magenta image by the optical unit 12b, and the photosensitive drum 10d irradiates a yellow image by the optical unit 12b. .

Therefore, a black toner image is formed on the photosensitive drum 10a, a cyan toner image is formed on the photosensitive drum 10b, a magenta toner image is formed on the photosensitive drum 10c, and a photosensitive toner image is formed on the photosensitive drum 10d. A yellow toner image is formed.

Therefore, the paper in the hopper 30 is conveyed to the recording unit 1 by the conveyor belt 32, the yellow toner is transferred on the photosensitive drum 10d, and then the photosensitive drum 10c is transferred.
The magenta toner is transferred by the
The cyan toner is transferred by b, and finally the photosensitive drum 1
0a, the black toner is transferred, and the conveyor belt 33
Thus, it is sent to the heat fixing device 2, is heat-fixed, and is housed in the stacker 31.

In such a color printing apparatus, the toner layer of the paper becomes about four times as large as that of monochrome (black and white) printing, and the toner layer thickness becomes thick, so that fixing is difficult. Particularly, in the heat fixing device 2, since the heat roller 21 applies heat to the upper side of the sheet, it is difficult to fix the toner on the lower side of the sheet. Therefore, the preheater 20 is provided to preheat the back side of the sheet,
Auxiliary heating to soften the toner, 40 °
A temperature of about C is suitable.

(B) Description of one embodiment FIG. 4 is a block diagram of one embodiment of the present invention, FIG. 5 is a process flow chart of one embodiment of the present invention, and FIG. 6 is a time chart diagram of one embodiment of the present invention. FIG. 7 is an operation explanatory diagram of an embodiment of the present invention.

In FIG. 4, the same components as those shown in FIGS. 1 to 3 are designated by the same reference numerals, and 24 is a heater, which is provided inside the heat roller 21 and heats the heat roller 21. Numeral 25 is a thermistor for the heat fixing device, for detecting the temperature of the heat roller 21,
26 is a thermistor for the preheater, which is the preheater 20.
It is for detecting the temperature of.

Reference numeral 40 denotes an A / D (analog / digital) converter, which converts the analog detected temperature output of each thermistor 25, 26 into a digital temperature output and inputs it to a control unit (CPU) 43 described later, Reference numeral 41 is a power supply for the preheater, which is controlled by the control unit 43.
Reference numeral 42 denotes a power source for the heat fixing device, which changes the current flowing to 0, and supplies a current to the heater 24 according to the heat fixing device control signal of the control unit 43.

Reference numeral 43 denotes a control unit, which is composed of a CPU (processor) and receives a jam signal and a reset signal and controls heating of the heater 24 and the preheater 20.
Is a control ROM for storing the control program of the control unit 43.

The jam processing operation will be described with reference to FIGS. 6 and 7 according to the processing flow chart of FIG. A control unit (hereinafter, referred to as a processor) 43 sends a ready (Redy) signal to notify a printable (fixable) state to a main control unit (not shown) of the printer to enable normal printing.

The processor 43 reads the detected temperature of the thermal fixing device thermistor 25 via the A / D converter 40, and the temperature of the thermal fixing device 2 is the set printing temperature.
It is determined whether the temperature is 0 ° C, and if it is not the set print temperature, the process returns to step.

When the temperature of the heat fixing device 2 reaches the set printing temperature, the processor 43 controls the preheater power source 41 to turn on 40 ° C so that the temperature of the preheater 20 is returned to the normal printing temperature of 40 ° C. A signal is given to control the temperature of the preheater 20 to 40 ° C.

The processor 43 detects a paper jam and determines whether a paper jam signal has arrived from the main control unit. If the jam signal has not arrived, the process returns to step. When the processor 43 determines that the jam signal has arrived, the processor 43 instructs the thermal fixing device power supply 42 to turn off the heater 24, turns off the heater 24, and then supplies the preheater power supply 41.
Then, a 60 ° C on control signal is given to raise the temperature of the preheater 20 to 60 ° C.

As a result, the temperature of the heat roller 21 is
As shown in FIG. 7, the set temperature decreases from 180 ° C., and the temperature of the preheater 20 increases from 40 ° C. to 60 ° C.

The processor 43 determines whether the reset signal has arrived after the jam processing is completed. When the processor 43 determines that the reset signal has arrived, the heat fixing device power supply 42 is supplied with 180 ° C. of the heater 24.
The control 24 is instructed to be turned on, and the heater 24 is turned on.

As a result, as shown in FIG. 7, the temperature of the heat roller 21 rises toward 180 ° C. The processor 43 reads the temperature detected by the thermistor 25 for the thermal fixing device via the A / D converter 40, and is a ready temperature equal to or lower than the set printing temperature (180 ° C.) 170.
Check whether it has reached ° C.

When the temperature of the heat roller 21 reaches 170 ° C., the processor 43 returns to the step, raises the ready signal to enable printing, and when the temperature of the heat roller 21 reaches 180 ° C., the temperature of the preheater 20. 40 °
Return to C.

The processor 43 always reads the temperature detected by the thermistor 25 for the thermal fixing device and the temperature detected by the thermistor 26 for the preheater via the A / D converter 40, and the temperature of the heat roller 21 is set to 180 ° C. , The thermal fixing device power supply 42 and the preheater power supply 41 are controlled so that the temperature of the preheater 20 is maintained at 40 ° C. or 60 ° C.

This will be described with reference to FIG. 7. During normal printing, the temperature of the heat roller 21 is controlled to 180 ° C. and the temperature of the preheater 20 is controlled to 40 ° C., and a paper jam is detected. Then, the heater 24 is turned off, the temperature of the heat roller 21 decreases, and the temperature of the preheater 20 becomes 60.
The ° C control is turned on and the temperature of the preheater 20 is 60 °.
The temperature rises toward C, and when it reaches 60 ° C, it is maintained at 60 ° C.

Next, when the jam processing is completed and reset is performed, the 180 ° C control of the heat roller 21 is turned on,
When the heater 24 is turned on and the temperature of the heat roller 21 rises and reaches the ready temperature (170 ° C.) below the set temperature, a ready signal is output to enable printing.

At this time, the paper temperature immediately after the heat fixing device is 6
Preheated at 0 ° C preheater 20 and then 170 ° C
Since it is heated by the heat roller 21 of, as shown in FIG.
The fixing was good at about 150 ° C.

After that, the temperature of the heat roller 21 is 18
The temperature rises to 0 ° C, is maintained at 180 ° C, and the temperature of the preheater 20 is returned to 40 ° C. Therefore, the paper temperature immediately after the heat fixing device rises from about 150 ° C. until the 60 ° C. control of the preheater 20 is turned off, but when it is turned off, it converges to about 150 ° C.

As described above, in order to raise the temperature of the preheater 20 when the heater 24 rises, the ready temperature (170 ° C.) lower than the set printing temperature (180 ° C.)
Since a paper temperature of about 150 ° C. is obtained for good fixing, a ready signal is generated at the time of reaching the ready temperature to enable printing, and the warm-up time from reset to ready can be shortened.

As shown in FIG. 7, the temperature of the backup roller 22 is low after the ready signal is generated.
Moreover, since there is temperature unevenness, the heat roller 2 is conventionally used.
The heat of 1 is taken away, the temperature unevenness is large as shown by the dotted line in the figure,
Although the fixing is not stable, in the present invention, since the temperature of the preheater 20 is raised, the amount of heat taken by the backup roller 22 can be accumulated on the sheet, and the amount is small as shown by the solid line in the figure.
Fixing can be stabilized from the beginning.

(C) Description of Other Embodiments In addition to the above embodiments, the present invention can be modified as follows. Although the recording unit 1 is described as an electrophotographic mechanism in the above-described embodiments, it may be used as a printing mechanism (for example, an electrostatic recording mechanism) that transfers a toner image.

The medium is not limited to paper, but other mediums can be used and may be cut media. Although the image recording apparatus has been described as a printer, it may be another image recording apparatus such as a copying machine or a facsimile.

Although the color printing apparatus has been described, it can be applied to a monochrome (black and white) printing apparatus. The timing at which the preheater 20 is controlled at 60 ° C. is set to the OFF time of the heater 24 in consideration of the rising of the preheater 20. However, before the heat roller 21 reaches the ready temperature, that is, before the heat roller 21 reaches the ready temperature. May be 60 ° C.

Although the occurrence of the alarm has been described with respect to the paper jam, it may be an alarm of another device such as an abnormality of the pre-charger. Although the present invention has been described with reference to the embodiments, various modifications are possible within the scope of the gist of the present invention, and these modifications are not excluded from the scope of the present invention.

[0053]

As described above, according to the present invention,
It has the following effects. Since the temperature of the preheater 20 is raised when the heat roller 21 rises, good fixing can be achieved and the warm-up time can be shortened even if the heat roller 21 does not reach the set temperature.

Further, stable fixing is possible from the initial stage of the ready state, and fixing failure can be prevented.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a configuration diagram of a color printing apparatus according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a main part of a color printing apparatus according to an embodiment of the present invention.

FIG. 4 is a configuration diagram of an embodiment of the present invention.

FIG. 5 is a processing flowchart of an embodiment of the present invention.

FIG. 6 is a time chart diagram of an example of the present invention.

FIG. 7 is an operation explanatory diagram of the embodiment of the present invention.

FIG. 8 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 2 Heat roller fixing device 20 Preheater 21 Heat roller 22 Backup roller 43 Control unit

Claims (4)

[Claims] 1. A heat roller (21) and a pressure roller (2)
The heat roller fixing device (2) for thermally fixing the toner on the medium through the medium holding the toner image between the heat roller fixing device (2) and the heat roller fixing device (2), and the medium is provided. And a preheater (20) for supplementarily heating the heating roller (21), when the alarm is generated, the heating of the heating roller (21) is turned off, and the heating of the heating roller (21) is turned on by resetting to warm up. After that, in the heat fixing device capable of fixing, a control part (43) for controlling heating of the heat roller (21) and the preheater (20) is provided, and the control part (43) indicates that the alarm has occurred. The heat fixing device is characterized in that the temperature of the preheater (20) is controlled to a higher temperature than usual in accordance with the above. 2. The controller (43) returns the temperature of the preheater (20) to a normal temperature when the heat roller (21) reaches a set temperature after the warm-up is completed. The heat fixing device according to claim 1. 3. The control unit (43) enables fixing before the heat roller (21) reaches the set temperature by the warm-up.
Heat fixing device. 4. The heat fixing device according to claim 1, wherein the medium holding the toner image has toner of each color transferred thereon.