JPH08262920A - Thermal fixing device - Google Patents

Abstract

PURPOSE: To prevent abnormality in temperature control caused by erroneous wiring. CONSTITUTION: In this thermal fixing device provided with two heating units 12 and 13 constituted in accordance with the size of a paper sheet applicable to the device and two temperature detectors 14 and 15 used for the independent lighting control of two heating units 12 and 13, a discriminating means 20 for discriminating the correspondence relation between two heating units 12 and 13 and two temperature detectors 14 and 15 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat fixing device used in copying machines, printers, facsimiles and the like.

[0002]

2. Description of the Related Art A heat fixing device is used in a copying machine, a printer, a facsimile, and the like, and includes a heat roller fixing device and an atmosphere fixing device that fix toner on a sheet by a fixing roller and a pressure roller. The heat roller fixing device is divided into two heat generators according to the size of usable paper, a fixing roller heated by the two heat generators, and pressed against the fixing roller. Fixing is performed by controlling the pressure roller, two temperature detectors provided corresponding to the two heat generators, and independent lighting control of the two heat generators by temperature detection signals from the two temperature detectors. A control unit that controls the surface temperature of the roller to an appropriate temperature, and heats and pressurizes the paper passing between the fixing roller and the pressure roller by the fixing roller and the pressure roller, thereby applying the heat to the paper There is one that fixes the toner of.

Further, in Japanese Patent Application Laid-Open No. 3-185482, a heating roller having a heater for heating therein, a pressure roller in contact with the heating roller at a predetermined pressure, and drive control of the heater are disclosed. And a transfer material having an unfixed image is fixed between the heating roller and the pressure roller while being conveyed while sandwiched between the heating roller and the pressure roller. A first heater whose heat generation amount at both end portions is larger than that of the central portion and a second heater whose heat generation amount at the central portion is larger than those of the both end portions are provided, and the driving means for the heater is the first heater. There is described a fixing device, which is set so that the first heater is energized when paper is passed and when it is not passed, and the second heater is energized only when paper is passed. .

Japanese Unexamined Patent Publication No. 4-240683 discloses a fixing roller which has a heat source inside and rotates, a pressure roller which rotates in pressure contact with the fixing roller, and a detecting means for detecting the surface temperature of the fixing roller. And a control means for controlling the heat source by a signal from the detection means to control the surface temperature of the fixing roller to a predetermined temperature, wherein the heat source distributes the heat amount along the axial direction of the fixing roller. However, the transfer paper and the first detection means, which is composed of a plurality of rod-shaped heating elements selectively used one of them and which is arranged in the normal paper passage area of the fixing roller, are most commonly used. And a second detecting means disposed in a region where it is difficult to print, controls the heating element based on the temperature signal from the first detecting means, and has an upper limit value of the temperature signal from the second detecting means. under Fixing apparatus characterized by the ability to use switch the heating element on the basis of the value was assigned to the control unit are described.

Japanese Laid-Open Patent Publication No. 57-63570 discloses a fixing device for fixing a toner image on a carrier material by nipping and carrying the toner image bearing material on a pair of rollers, at least one of which is heated. And a heating means having a plurality of heat sources having different heat distributions in the longitudinal direction of the rollers, a temperature detecting means for detecting the temperature of at least one of the pair of rollers at a plurality of positions different in the longitudinal direction of the rollers, and this temperature. A fixing device is provided, which comprises a control means for selectively operating the plurality of heat sources in response to a signal from the detection means.

In Japanese Patent Laid-Open No. 21665/1990, a roller for contacting and rotating an image recording medium carrying a toner image to fix the toner image on the image recording medium is shorter than the entire axial length of the roller. A first heater that heats a first region, a second heater that heats a second region other than the first region in the axial direction of the roller, and a first region of the roller are provided in this region. A temperature detecting means for detecting the surface temperature of the roller, a control circuit for on / off controlling the first heater and the second heater based on the temperature detected by the temperature detecting means, and a second area of the roller. A toner image fixing device is described, which has a temperature switch that turns off the second heater when the temperature of this region exceeds a predetermined temperature.

In Japanese Patent Laid-Open No. 57-53773, a heat roller fixing device for fixing a toner image on a recording sheet by a heating roller and a pressure contact roller in pressure contact with the heat roller has a thermal conductivity of 100 Kcal / m · h · deg. The core metal of the heating roller is formed from the following materials, and the heater light emission length required for the maximum paper-passing size is divided into two parts within this core metal.
It is described that the heaters are divided and arranged so that their light emitting portions are shifted so as not to overlap with each other, and two temperature detecting elements are provided on the core metal of the heating roller so as to correspond to the two heaters. .

[0008]

In the above heat fixing device, two heat generators, a fixing roller heated by these two heat generators, and two heat generators provided corresponding to the two heat generators are provided.
One temperature detector and a control means for controlling the surface temperature of the fixing roller to an appropriate temperature by independently controlling the lighting of the two heat generators by the temperature detection signals from the two temperature detectors. If the two temperature detectors corresponding to the two heat generators are installed opposite to each other due to incorrect wiring, the independent lighting control of each of the two heat generators becomes abnormal and proper temperature control cannot be performed. Also, in other fixing devices, if the temperature detector is installed in an improper position due to incorrect wiring, proper temperature control cannot be performed. SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermal fixing device that can solve the above problems and prevent abnormal temperature control due to erroneous wiring.

[0009]

In order to achieve the above object, the invention according to claim 1 has two heat generators configured according to the size of a sheet usable in the apparatus, and two heat generators.
A heat fixing device having two temperature detectors used for independent lighting control of two heat generators, which is provided with a discriminating means for discriminating the correspondence between the two heat generators and the two temperature detectors. is there.

According to a second aspect of the present invention, in the heat fixing device according to the first aspect, the above-mentioned step 2 is performed until the determination of the correspondence between the two heat generators and the two temperature detectors by the determination means is completed. Only one of the two heat generators is turned on.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the heat fixing device described above, the determination means determines the correspondence between the two heat generators and the two temperature detectors for a predetermined time after one of the two heat generators is turned on. This is performed based on the temperature detection values from the two temperature detectors later.

The invention according to claim 4 is the invention according to claim 1 or 2.
In the heat fixing device described above, the determination means determines the correspondence between the two heat generators and the two temperature detectors after the first heat generator of one of the two heat generators lights up. Is performed based on the temperature detection values from the two temperature detectors after the predetermined time and the temperature detection values from the two temperature detectors after the second predetermined time.

[0013]

According to the first aspect of the invention, the discriminating means discriminates the correspondence between the two heat generators and the two temperature detectors. According to a second aspect of the present invention, in the heat fixing device according to the first aspect, one of the two heat generators is provided until the determination of the correspondence between the two heat generators and the two temperature detectors by the determination means is completed. Only the heat generator of is turned on.

In the invention according to claim 3, the discriminating means is 2
Determine the correspondence between one heat generator and two temperature detectors in 2
This is performed based on the temperature detection values from the two temperature detectors after a predetermined time has passed after one of the two heat generators is turned on. According to a fourth aspect of the present invention, in the heat fixing device according to the first or second aspect, the determination unit determines the correspondence between the two heat generators and the two temperature detectors by using one of the two heat generators. The temperature detection values from the two temperature detectors after the first predetermined time from the lighting of the heat generator and the two after the second predetermined time.
Based on the temperature detection value from one temperature detector.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the outline of one embodiment of the present invention. This embodiment is an embodiment of the invention described in claims 1 to 4, and is an example of a heat roller fixing device used in a copying machine, a printer, a facsimile or the like. The heat roller fixing device has a fixing roller 11 and a pressure roller (not shown) that is in pressure contact with the fixing roller 11, and fixes the fixing roller 11 to a sheet passing between the fixing roller 11 and the pressure roller. Then, the toner on the paper is fixed by heating and pressing by the pressure roller.

Inside the fixing roller 11, there are provided heaters 12 and 13 as two heat generators which are constructed in accordance with the size of the paper usable in the apparatus. The heater 12 heats the central portion of the fixing roller 11, and the heater 13 heats both end portions of the fixing roller 11. 2 on the surface of the fixing roller 11.
Thermistors 14 and 15 as two temperature detectors used for independent lighting control of the two heaters 12 and 13 are provided corresponding to the heaters 12 and 13, and the thermistor 14 detects the temperature of the central portion of the fixing roller 11. Thermistor 15
Detects the temperature of both ends of the fixing roller 11.

One end of each of the heaters 14 and 15 is AC100V through the normally open contact RA1a of the AC system interruption relay RA1.
Is connected to the AC power source and the other end is connected to the ground via the switch elements 16 and 17 each made of a triac. The triacs 16 and 17 are driven by drivers 18 and 19, respectively, and the drivers 18 and 19 are CPUs.
It is controlled by the control means 20 including a (microcomputer). The coil of the AC system interruption relay RA1 is connected to a DC 24V power source via the transistor 21, and the transistor 21 is driven by the driver 22.

As will be described later, if there is no miswiring, the CPU 20 controls the driver 18 by the temperature detection signal from the thermistor 14 to turn on / off the triac 16, thereby controlling the turning on / off of the heater 12. The driver 19 is controlled by the temperature detection signal from the thermistor 15 to turn on / off the triac 17, thereby controlling the turning on / off of the heater 13. In this case, C
The PU 20 internally A / D-converts the temperature detection signals from the thermistors 14 and 15, and converts the temperature detection signals of the fixing roller 11 based on a program.

Although this embodiment is used in a copying machine or the like, the input signal from the cover switch of the copying machine is the CPU 20.
Is input to The cover switch is turned on / off by opening / closing the cover of the copying machine or the like to detect the open / closed state of the cover of the copying machine or the like. When the cover is opened, the CPU 20 controls the driver 22 to turn off the transistor 21 when the cover is opened by an input signal from the cover switch, thereby cutting off the power supply to the coil of the AC system breaking relay RA1 and opening the normally open contact RA1a. As a result, electric power is not supplied from the power source to the heaters 12 and 13. Further, the CPU 20 controls the driver 22 to turn on the transistor 21 when the cover is closed by the input signal from the cover switch, thereby turning on the AC.
The coil of the system cut-off relay RA1 is energized to close the normally open contact RA1a, whereby the heater 1
Power supply to 2 and 13 is triac 16 and 1 respectively
It is performed when 7 is turned on.

2 to 5 show the CPU 20 in this embodiment.
3 is a flowchart showing the control contents of FIG. Figure 2 CPU
20 shows a processing flow when the power of 20 is turned on. The CPU 20
When the power is turned on, various initialization processing is performed, and the "power ON flag" indicating that the power is turned on is turned on. It should be noted that the CPU 20 performs the processing flow at power-on only once at power-on.

FIG. 3 shows a processing flow for the CPU 20 to start the temperature detector discrimination processing (discrimination of the correspondence between the temperature detectors 14 and 15 and the heaters 12 and 13). C
The PU 20 first checks whether or not the “power ON flag” is on to determine whether or not the power is on, and returns if the “power ON flag” is not on. Further, the CPU 20 turns off the "power supply ON flag" if the "power supply ON flag" is on, and controls the driver 18 to turn on one of the two heaters 12, 13.

Next, the CPU 20 makes the temperature detectors 14, 1
At this time, that is, at an arbitrary time after the heater 12 is turned on, after turning on the “temperature detector determining flag” indicating that the correspondence between the heaters 12 and 13 of No. 5 is being determined, The temperature detection signal from the thermistor 14 is read and stored in the "first temperature (1)" buffer,
By reading the temperature detection signal from the thermistor 15, “first
Store in temperature (2) "buffer.

Finally, the CPU 20 reads the temperature detection signals of the respective temperature detectors after a lapse of an arbitrary time to determine the correspondence between the temperature detectors 14 and 15 and the heaters 12 and 13. Start the timer. The CPU 20 executes this processing flow only when the "power ON flag" is ON. Therefore, like the processing flow of FIG. 2, the processing flow of FIG.
Only executed once.

FIG. 4 is a processing flow for the CPU 20 to receive the processing flow of FIG. 3 and determine the correspondence between the temperature detectors 14 and 15 and the heaters 12 and 13. CPU2
For 0, first, in order to determine whether or not the processing flow of FIG. 3 has been executed, it is checked whether or not the “temperature detector discrimination flag” is on, and the “temperature detector discrimination flag” is on. If not, it returns.

If the "temperature detector discrimination flag" is on, the CPU 20 checks whether the "second temperature reading timer" has timed out, and the "second temperature reading timer" has timed up. If not, it returns. The CPU 20 receives the start processing of the "second temperature reading timer" according to the processing flow of FIG. 3, and adds the "second temperature reading timer" with the progress of time by the timer count-up processing (not shown). CPU
20 indicates that the "temperature sensor discrimination flag" is turned on and the "second
If the "timer for reading temperature" has timed out, the "temperature sensor discrimination flag" is turned off to indicate the end of the discrimination of the correspondence between the temperature detectors 14 and 15 and the heaters 12 and 13, and the processing flow of FIG. The following processing is performed as shown.

The CPU 20 first reads the temperature detection signal from the thermistor 14 and stores it in the "second temperature (1)" buffer, and reads the temperature detection signal from the thermistor 15 to "second temperature (2)". Stored in the buffer. Next, the CPU 20 calculates the difference between the temperature data in the “second temperature (1)” buffer and the temperature data in the “first temperature (1)” buffer to detect the temperature change of the thermistor 14. Then, the difference is stored in the "temperature difference 1" buffer. Further, the CPU 20 obtains the detected temperature change of the thermistor 15 by calculating the difference between the temperature data in the "second temperature (2)" buffer and the temperature data in the "first temperature (2)" buffer. , The difference is stored in the “temperature difference 2” buffer.

Next, the CPU 20 compares the detected temperature change of the thermistor 14 and the detected temperature change of the thermistor 15 by comparing the data in the buffer having the "temperature difference 1" with the data in the buffer having the "temperature difference 2". Are compared to determine the correspondence between the temperature detectors 14 and 15 and the heaters 12 and 13. Here, since the heater 12 is turned on and the heater 13 is turned off, the CPU 20 heats the thermistor 14 if the data in the "temperature difference 1" buffer is larger than the data in the "temperature difference 2" buffer. It is determined that the thermistor 15 is compatible with the heater 13 and that the data in the buffer with the "temperature difference 1" is larger than the data in the buffer with the "temperature difference 2". For example, the thermistor 15 is determined to correspond to the heater 12, and the thermistor 14 is determined to correspond to the heater 13.

FIG. 5 is a processing flow in which the CPU 20 performs normal temperature control. CPU20 is "power ON flag"
And the "temperature detector discrimination flag" are checked and either or both of them are off, that is, while the correspondence between the temperature detectors 14 and 15 and the heaters 12 and 13 cannot be discriminated. Return without temperature control, "Power ON flag" and "Temperature detector discriminating flag"
If both are on, normal temperature control is performed.

In the normal temperature control, the CPU 20 controls the driver 18 on the basis of the temperature detection signal from the thermistor which is determined to correspond to the heater 12 among the thermistors 14 and 15 to turn on / off the triac 16. By doing so, the heater 12 is turned on / off to control the surface temperature of the central portion of the fixing roller 11 to be constant, and the temperature from the thermistor that is determined to correspond to the heater 13 among the thermistors 14 and 15 is controlled. Based on the detection signal, the driver 19 is controlled to turn on / off the triac 17, thereby controlling the turning on / off of the heater 13 and controlling the surface temperature of both ends of the fixing roller 11 to be constant.

As described above, the present embodiment is an embodiment of the invention described in claim 1, and includes two heat generators 12 and 13 which are configured according to the size of the paper usable in the apparatus.
Thermistors 14 and 15 as two temperature detectors used for independent lighting control of these two heat generators 12 and 13.
In the heat fixing device having the two heat generators 12, 1
Since the CPU 20 that also serves as a determination unit that determines the correspondence between the temperature detectors 14 and 15 and the temperature detectors 14 and 15 is provided, abnormal lighting control of the heat generators 12 and 13 due to incorrect wiring of the temperature detectors 14 and 15 is prevented. can do.

Further, the present embodiment is an embodiment of the invention according to claim 2, wherein in the heat fixing device according to claim 1,
2 until the determination of the correspondence between the two heat generators 12 and 13 and the two temperature detectors 14 and 15 by the determination means is completed.
Since only one of the two heat generators 12 and 13 is turned on, the two heat generators 12 and 13 by the determination means are turned on.
As compared with the case where the two heat generators 12 and 13 are turned on at the same time and the temperature rise in the vicinity thereof is made substantially the same until the determination of the correspondence between the two temperature detectors 14 and 15 is completed. The difference between the temperature rise in the vicinity of 12 and the temperature rise in the vicinity of the heat generator 13 becomes large, and the above determination can be easily performed by the determination means.

Further, the present embodiment is an embodiment of the invention according to claim 3, and in the heat fixing device according to claim 1 or 2, the discriminating means includes two heat generators 12 and 13 and two temperatures. The determination of the correspondence with the detectors 14 and 15 is based on the temperature detection values from the two temperature detectors 14 and 15 after an arbitrary time has elapsed after one of the two heat generators 12 and 13 is turned on. Since one of the heaters 12 is turned on and left for an arbitrary period of time, the temperature in the vicinity of the heater 12 rises remarkably, and the temperature in the vicinity of the other unlit heater 13 rises so much. Therefore, the determination can be performed in a state where the difference between the temperature in the vicinity of the heat generator 12 and the temperature in the vicinity of the heat generator 13 is wide open, and the reliable determination can be performed.

Further, the present embodiment is the embodiment of the invention described in claim 4, and in the heat fixing device according to claim 1 or 2, the discriminating means has two heat generators 12 and 13 and two temperatures. For determining the correspondence with the detectors 14 and 15, the temperature from the two temperature detectors 14 and 15 after the first arbitrary time after one of the two heat generators 12 and 13 lights up. Detected value and two temperature detectors after the second arbitrary time 1
Since it is performed based on the temperature detection values from Nos. 4 and 15, no matter what temperature the two heat generators 12 and 13 have before the discrimination, the first predetermined time and the The difference between the temperatures of the temperature detectors 14 and 15 after the predetermined time of 2 allows easy and reliable determination.

[0034]

As described above, according to the first aspect of the present invention, two heat generators configured according to the size of the paper usable in the apparatus and independent lighting control of the two heat generators are provided. In the thermal fixing device having two temperature detectors used for the above, since the determination means for determining the correspondence relationship between the two heat generators and the two temperature detectors is provided, heat generation due to incorrect wiring of the temperature detectors. It is possible to prevent abnormal lighting control of the container.

According to the invention described in claim 2, in the thermal fixing device according to claim 1, until the determination of the correspondence between the two heat generators and the two temperature detectors by the determination means is completed. Since only one of the two heat generators is turned on, the two heat generators and
2 by the time the determination of the correspondence with one temperature detector is completed
Compared with the case where two heat generators are turned on at the same time and the temperature rises in the vicinity thereof are made substantially the same, the difference between the temperature rises in the vicinity of the two heat generators becomes large, and the above determination can be easily performed by the determination means. it can.

According to a third aspect of the present invention, in the thermal fixing device according to the first or second aspect, the determining means determines the correspondence between the two heat generators and the two temperature detectors. Since it is performed based on the temperature detection value from the two temperature detectors after a lapse of a predetermined time after one of the two heat generators is turned on, it is left for a predetermined time after one of the heat generators is turned on. As a result, the temperature near the heat generator rises significantly and the temperature near the other non-lighted heat generator does not rise so much. Therefore, it is determined that the temperature difference between the two heat generators is wide open. Can be done
It is possible to make a reliable determination.

According to a fourth aspect of the invention, in the heat fixing device according to the first or second aspect, the determining means determines the correspondence between the two heat generators and the two temperature detectors. The temperature detection value from the two temperature detectors after a first predetermined time from the lighting of one of the two heat generators and the temperature detection value from the two temperature detectors after a second predetermined time from Since it is performed based on the temperature detection value, no matter what temperature the two heat generating devices have before the discrimination, one of the heat generating devices after the first predetermined time and the second predetermined time after one of the heat generating devices lights up. It is possible to easily and surely make a determination based on the temperature difference between the temperature detectors.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a processing flow when the power of the CPU is turned on in the embodiment.

FIG. 3 is a flowchart showing a processing flow for starting the temperature detector determination processing of the CPU in the embodiment.

FIG. 4 is a flowchart showing a processing flow for determining a temperature detector of the CPU in the embodiment.

FIG. 5 is a flowchart showing a processing flow for performing normal temperature control of the CPU in the embodiment.

[Explanation of symbols]

 11 Fusing roller 12, 13 Heater 14, 15 Thermistor 16, 17 Triac 18, 19 Driver 20 CPU

Claims (4)

[Claims] 1. A heat fixing device having two heat generators configured according to the size of a sheet usable in the apparatus and two temperature detectors used for independent lighting control of the two heat generators. The heat fixing device according to claim 1, further comprising a determination unit that determines a correspondence relationship between the two heat generators and the two temperature detectors. 2. The heat fixing device according to claim 1, wherein the determination means determines the correspondence between the two heat generating elements and the two temperature detectors, and the two heat generating elements out of the two heat generating elements. A thermal fixing device characterized in that only one heating device is turned on. 3. The thermal fixing device according to claim 1, wherein the determining means determines the correspondence between the two heat generators and the two temperature detectors from one of the two heat generators. The heat fixing device is characterized in that it is carried out based on the temperature detection values from the two temperature detectors after a predetermined time has passed since the heat generator was turned on. 4. The thermal fixing device according to claim 1, wherein the determination means determines the correspondence between the two heat generators and the two temperature detectors from one of the two heat generators. Is performed based on the temperature detection values from the two temperature detectors after a first predetermined time from the lighting of the heat generator and the temperature detection values from the two temperature detectors after a second predetermined time. A heat fixing device characterized by.