JP3350315B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device,
More specifically, the present invention relates to a fixing device which is applied to a recording device of an electrophotographic system or the like and fixes toner adhered to the recording paper to the recording paper by a fixing heater.

[0002]

2. Description of the Related Art Recently, a so-called electrophotographic recording apparatus has been used as a recording apparatus because of its good print quality.

In such an electrophotographic recording apparatus, an electrostatic latent image is formed on a photosensitive member by light modulated based on image data, and toner is adhered to the photosensitive member on which the electrostatic latent image is formed. And develop. The toner adhered to the photoreceptor is transferred onto a recording paper, and the recording paper with the toner adhered is conveyed to a fixing roller, and the toner is fixed on the recording paper by the fixing roller.

The fixing roller is heated by a fixing heater to be controlled at a predetermined fixing temperature.
An overheating prevention process has been performed.

That is, in the conventional fixing device, the temperature of the fixing roller is detected by a thermistor or the like, and the detected temperature is set to a predetermined ON / OFF value around the fixing temperature.
When the temperature reaches the OFF temperature, the control circuit controls ON / OFF of the fixing heater to control the fixing roller to the fixing temperature. Also, in case of an abnormality such as runaway of the control circuit,
The overheating protection of the fixing heater is performed by a thermal fuse or a thermostat, and the overheating of the fixing heater is performed by an analog comparator.

However, such a conventional temperature control method has a problem that the temperature ripple and overshoot of the fixing roller increase.

Therefore, conventionally, as described in Japanese Patent Application Laid-Open No. 5-297758, a first temperature lower than a predetermined temperature is set.
And a second temperature higher than the predetermined temperature, and the amount of power to be supplied is changed depending on whether the detected temperature of the fixing roller is the first temperature or the second temperature. There has been proposed a fixing device that suppresses overshoot and small.

[0008]

However, such a conventional fixing device is still insufficient to suppress the temperature ripple and the overshoot, the fixing property is unstable, and the image quality is deteriorated. There was a problem of doing.

That is, in the fixing device described in Japanese Patent Application Laid-Open No. 5-297758, energization of the fixing heater is performed based on the first temperature and the second temperature based on the detection result of the temperature detector. Because the amount of power supplied to the fixing heater was changed to control the temperature of the fixing roller, the control of the heating speed of the fixing heater was coarse, and the temperature ripple and overshoot could not be sufficiently suppressed. There has been a problem that the fixing efficiency becomes unstable and the image quality deteriorates.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device having good fixing efficiency by controlling the power supply to the fixing heater finely to thereby appropriately suppress the temperature ripple and the overshoot.

[0011]

According to a first aspect of the present invention, there is provided a fixing device for fixing a toner transferred to a recording sheet to the recording sheet by a fixing member heated to a predetermined fixing temperature by a fixing heater. in the device, a temperature detection means for detecting a temperature of said fixing member, through the fixing heater
A predetermined period detected by the temperature detecting means from the start of power supply
Storage means for storing the detected temperature for one minute, and the stored predetermined period
Rise in the surface temperature of the fixing member based on the detected temperature for one minute.
The rising tendency is determined, and the lighting period in which the power to the fixing heater is energized and the light-off period in which the power to the fixing heater is stopped are set as the determined rising tendency as a determination factor. The above object is achieved by providing control means for controlling the power supply to the fixing heater based on the light-on period and the light-off period to control the temperature of the fixing member to the fixing temperature.

Here, the fixing heater may be of any shape or material as long as it can appropriately heat the fixing member to a predetermined fixing temperature.

The fixing temperature is a temperature suitable for fixing the toner transferred to the recording paper by the fixing member to the recording paper, and is appropriately set in accordance with conditions such as the material of the fixing member, the recording paper, and the environmental temperature. .

The fixing member is usually a fixing roller, but is not limited to the fixing roller.

The temperature detecting means can use a thermistor or the like, but is not limited to a thermistor, and directly detects the temperature of the fixing member or appropriately detects the temperature near the fixing member from which the temperature of the fixing member can be calculated. Anything that can do so may be used.

Here, the control means sets the temperature of the fixing member.
The rising tendency, for example, from a predetermined temperature to a predetermined temperature,
Alternatively, the temperature detected by the temperature detecting means for a predetermined period is stored.
Based on the temperature change state of the detected temperature.
Judgment is based on how the material temperature rises
You.

According to the above configuration, the constant value differs for each fixing member.
Considering the rising tendency of the temperature of the
The power supply to the fixing device can be controlled,
The temperature control can be performed.

Further , for example, as described in claim 2
The control means may detect the temperature detected by the temperature detection means and
Calculate the temperature difference from the fixing temperature, and calculate the temperature difference
One of the judgment factors for setting the lighting period and the extinguishing period is
You may.

The control means is a CPU (Central Processing)
Unit) can be used, and the detected temperature of the temperature detecting means
Temperature as the temperature of the fixing member, or the detected temperature
The temperature of the fixing member is calculated from
The temperature difference from the fixing temperature is calculated, and the ROM (Read Onl
y Data) etc. stored in Memory etc.
By setting the lighting period and the turning-off period of the fixing heater,
Set and set based on the set lighting period and lighting period
Controls the power supply to the heater.

According to the above arrangement, the temperature of the fixing roller is fixed.
Turns on the fixing heater based on the temperature difference from the
Fine control, temperature ripple and over
Fix the fixing roller to the fixing temperature properly while preventing shoots.
Can be controlled. As a result, the fixability is improved.
Image quality can be improved.

Further , for example, as described in claim 3
The control means may be configured to control the temperature based on the temperature detected by the temperature detection means.
The temperature change tendency of the fixing member is determined based on the
The change tendency is determined by the determination of the setting of the lighting period and the lighting period.
It may be one of the disconnection elements.

Here, the control means controls the temperature change of the fixing member.
The tendency is detected, for example, by the temperature detection means of a predetermined period in the past.
The temperature is memorized, and based on the temperature change status of the detected temperature,
And how the temperature of the fixing member changes
And, for example, how much
Separate.

According to the above arrangement, the temperature change gradient of the fixing member is obtained.
Control the energization of the fixing heater in consideration of the direction
Finer and more precise in response to changes in the temperature of the fixing member
Temperature control can be performed.

Furthermore, for example, as described in claim 4
The fixing device may further include an input voltage value to the fixing heater.
Further comprising voltage detecting means for detecting
The detection result of the voltage detection means and the lighting period and the
This is one of the judgment factors for setting the light-off period.
You may.

Here, the voltage detecting means includes a fixing heater.
Power input to fuser heater to generate heat
This is to detect the voltage value.
Anything that can be detected
No.

According to the above arrangement, the input to the fixing heater is provided.
Control of energization to the fixing heater taking into account changes in voltage value
Temperature control of the fixing member
It can be performed.

Also, for example, as described in claim 5
In the fixing device, at least around the fixing member
Environmental temperature detecting means for detecting the environmental temperature,
The control means precedes the detection result of the environmental temperature detection means with
One of the above judgment factors for setting the lighting period and the turning-off period
May be used.

Here, the environmental temperature detecting means is provided for the fixing member.
This is to detect the environmental temperature
Anything that can properly detect temperature
Such a thing may be used.

According to the above configuration, the ambient temperature of the fixing roller
It is possible to control the power supply to the fixing heater in consideration of
More precise temperature control of the fixing member.
it can.

[0030]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are preferred specific examples of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention particularly limits the present invention in the following description. It is not limited to these embodiments unless otherwise stated.

FIGS. 1 to 8 are views showing an embodiment of the fixing device of the present invention. FIG. 1 is a circuit block diagram of a facsimile apparatus 1 to which an embodiment of the fixing device of the present invention is applied. It is.

In FIG. 1, the facsimile machine 1
PU (Central Processing Unit) 2, ROM (Read O
nly Memory) 3, RAM (Random Access Memory) 4,
A communication unit 5, a reading unit 6, an operation display unit 7, a plotter unit 8, a timer 9, and the like are provided. The plotter unit 8 includes a thermistor 10, an A / D conversion unit 11, a fixing heater 12, an output port 13, an input voltage A detection unit 14, a drive control unit 15, a laser control unit 16, an outside air temperature detection sensor 17, an A / D conversion unit 18, and the like are provided. CPU2, ROM3, RA
M4, communication unit 5, reading unit 6, operation display unit 7, A / D conversion unit 11, output port 13, drive control unit 15, laser control unit 16, and A / D conversion unit 18 are each connected to bus 20. ing.

The ROM 3 stores various data and system data necessary for executing the basic processing program of the facsimile machine 1, the temperature control program of the fixing heater 12, and the basic processing program and the temperature control program. Various table data of a lighting period (ON time) and a light OFF period (OFF time) of the fixing heater 12 used for the control processing are stored. The table data is obtained and set in advance by experiments or the like.

The CPU (control means) 2 controls each part of the facsimile machine 1 while using the RAM 4 as a work memory based on a program in the ROM 3, and performs basic processing as the facsimile machine 1 and temperature control of the fixing heater 12. Perform processing.

As described above, the RAM 4 is used as a work memory of the CPU 2 and also as a page memory in which write data for one page recorded by the plotter unit 8 is expanded. That is, in the RAM 4,
A page memory area is formed, and one page of write data recorded and output by the plotter unit 8 is developed in the page memory area of the RAM 4 by the CPU 2 and output to the laser control unit 16 of the plotter unit 8 by the CPU 2. You.

The communication unit 5 is connected to a line L, for example, a public telephone line, and performs automatic call / call-in processing, facsimile communication procedure execution processing, modulation / demodulation processing, image data compression / reproduction processing, and the like. I do.

The reading unit 6 is, for example, a CCD (Charge Cou
An image scanner using a pled device is used, and the scanner scans a document and reads an image of the document at a predetermined resolution.

The operation display unit 7 includes various operation keys such as a numeric keypad and a start key, and also includes a display (for example, a liquid crystal display). Various commands such as a transmission operation are input from the operation keys. In addition, the contents of instructions input from the operation keys and various information notified to the operator from the facsimile apparatus are displayed.

The timer 9 includes an oscillating circuit, a frequency dividing circuit, and the like, measures time, and outputs a result of the time measurement to the CPU 2. The CPU 2 controls each unit of the facsimile machine 1 based on the time measured by the timer 9, and particularly manages the lighting period and the light-off period of the fixing heater 12 when controlling the temperature of the fixing heater 12 as described later. Performed by timer interrupt.

The plotter section 8 uses a so-called electrophotographic recording apparatus, and is configured as shown in FIG.

That is, the plotter section 8 includes the photosensitive member 21,
The photoconductor 21 includes a cleaning unit 22, a charge removal unit 23, a charging unit 24, an exposure unit 25, a development unit 26, a transfer unit 27, a transfer roller 28, a paper discharge roller 29, and the like. ) Are driven to rotate. The plotter unit 8 modulates the laser on the photoreceptor 21 uniformly charged by the charging unit 24 based on image data which is write data by the laser control unit 16, and
To form an electrostatic latent image, and a developing unit 26 attaches toner to the photoreceptor 21 on which the electrostatic latent image is formed and develops the image. The plotter unit 8 transfers the toner adhered to the photoreceptor 21 to the recording paper 30 conveyed to the transfer unit 27 by a conveying roller from a recording paper cassette (not shown) by the transfer unit 27, and the toner adheres. Fixing the recording paper 30 to a fixing roller 28 as a fixing member
Transport to The plotter unit 8 controls the temperature of the fixing roller 28 by the CPU 2 while fixing the toner on the recording paper 30 by the fixing roller 28 and detecting the temperature of the fixing roller 28 by the thermistor 10. The photoreceptor 21 that has been transferred to the recording paper 30 is cleaned of residual toner by a cleaning unit 22, is discharged by a discharging unit 23, is charged by a charging unit 24, and is charged by a charging unit 24 to form a next electrostatic latent image. Is provided for the formation of

Referring again to FIG. 1, the thermistor (temperature detecting means) 10 detects the temperature of the fixing roller 28 and outputs an analog temperature detection signal to the A / D converter 11. The A / D converter 11 converts an analog temperature detection signal input from the thermistor 10 into a digital temperature detection signal, and outputs the digital temperature detection signal to the CPU 2 via the bus 20. Specifically, the thermistor 10 is disposed near the fixing roller 28, and the CPU 2 converts the temperature into the temperature of the fixing roller 28 based on the temperature detection signal to acquire the temperature of the fixing roller 28.

The fixing heater 12 is built in the fixing roller 28, and generates heat by turning on / off a power supplied from an external power source (not shown) according to a lighting signal and a light-off signal input from the output port 13. Then, the fixing roller 28 is heated.

The input voltage detector (voltage detector) 14
The input voltage value of the power supply supplied from the external power supply to the fixing heater 12 is detected, the detection result is converted into a digital signal, and the digital signal is output to the CPU 2 via the bus 20.

The drive control section 15 controls the operation of the drive section of the plotter section 8 based on a command from the CPU 2.

The laser control section 16 controls the drive of the laser light emitting section based on the write data (image data) transferred from the RAM 4, and controls the modulation of the laser corresponding to the write data.

Outside temperature detecting sensor (environmental temperature detecting means) 1
Reference numeral 7 denotes a normal temperature sensor, which detects the ambient temperature of the facsimile machine 1, particularly, the temperature around the fixing roller 28, and outputs an analog temperature detection signal to the A / D converter 18.

The A / D converter 18 is provided with the outside air temperature detection sensor 1
7 is converted into a digital signal, and is converted into a digital temperature detection signal.
To the CPU 2 via the.

Next, the operation will be described. In the communication mode, the facsimile apparatus 1 compresses image data of a document read by the reading unit 6 using a predetermined compression method, transmits the compressed image data to a destination, and temporarily stores the received image data in a RAM for each page.
After the image data is expanded in the page memory area of No. 4, the data is transferred to the plotter unit 8 and recorded on the recording paper 30. In the copy mode, the facsimile apparatus 1 develops the image data of the original read by the reading unit 6 into a page memory area of the RAM 4 for each page, and then transfers the image data to the plotter unit 8 and records and outputs the data on the recording paper 30 I do.

At the time of recording image data in the plotter section 8, the power supply to the fixing heater 12 is controlled to
It is necessary to control the fixing roller 28 heated by the fixing heater 12 to a suitable fixing temperature.

That is, based on the temperature detection signal of the fixing roller 28 detected by the thermistor 10 and digitally converted by the A / D converter 11, the CPU 2 outputs a lighting signal and a light-off signal via the output port 13 to the fixing heater. The output to the fixing roller 12 controls the power supply to the fixing heater 12 to control the fixing roller 28 to a fixing temperature appropriate for fixing the toner to the recording paper 30.

However, if the power supply to the fixing heater 12 is controlled based only on whether the fixing roller 28 is higher or lower than a predetermined ON / OFF temperature, temperature ripple and overshoot occur, and the fixing performance deteriorates. .

Therefore, in the facsimile machine 1,
The temperature difference between the control target fixing temperature and the temperature of the fixing roller 28, the temperature change tendency of the fixing roller 28, the fixing heater 12
The lighting period and the turning-off period of the fixing heater 12 are controlled based on the input voltage value to the outside, the outside air temperature (the environmental temperature of the fixing roller 28), the rising tendency of the temperature of the fixing roller 28, etc. Immediately to the fixing temperature,
And it controls with high precision.

That is, as shown in FIG. 3, in the recording process, the CPU 2 determines whether there is a write start request, that is, whether the receiving operation has been started, or a copy command is issued by key operation of the operation display unit 7. (Step S
1) If the data is received or copied, the write data is transferred to the page memory area of the RAM 4, and when transfer of all the write data for one page to the page memory area of the RAM 4 is completed, the data is output via the output port 13. Then, a heater lighting command is output to the fixing heater 12 to turn on the fixing heater 12 (step S2).

The CPU 2 checks whether the fixing roller 28 has reached a preset writing start temperature based on the temperature detection signal from the thermistor 10 (Step S).
3) When the writing start temperature is reached, the recording paper 30 is
Then, the write data developed in the page memory area of the RAM 4 is output to the laser control unit 16 and writing is started (step S4). That is, the laser control unit 16 modulates the laser according to the write data, and
An electrostatic latent image is formed by the light modulated to 1, and toner is adhered to the photoreceptor 21 on which the electrostatic latent image has been formed and developed. The toner adhered to the photoreceptor 21 is transferred to a recording paper 30, and the recording paper 30 having the toner adhered thereto is fixed to the fixing heater 12.
The toner is conveyed to the fixing roller 28 heated by the fixing roller 28, and the toner is fixed on the recording paper 30 by the fixing roller 28.

When writing is started, the CPU 2 compares the detected temperature (the temperature of the fixing roller 28) detected by the thermistor 10 with a preset continuous lighting temperature, and determines whether the detected temperature is higher than the continuous lighting temperature. Check (step S5). If the detected temperature does not exceed the continuous lighting temperature, the fixing heater 12 is continuously turned on, and again
It is checked whether the detected temperature is higher than the continuous lighting temperature (steps S6 and S5).

In step S5, when the detected temperature, that is, the temperature of the fixing roller 28 exceeds the continuous lighting temperature, the CPU
2 outputs a turn-off instruction to the fixing heater 12 via the output port 13, turns off the fixing heater 12 (step S7), and checks whether the detected temperature is higher than a preset fixing temperature (step S8). ).

In step S8, when the detected temperature is higher than the fixing temperature, the CPU 2
2 is turned off, and when the detected temperature falls below the fixing temperature, the duty for turning on / off the fixing heater 12, that is,
The lighting period and the turning-off period of the fixing heater 12 are set, and the turning-on and turning-off of the fixing heater 12 are controlled based on the set duty (steps S9 and S10).

Next, the CPU 2 checks whether the receiving or copying operation has been completed (step S11). If not, the process returns to step S8 to compare the detected temperature with the fixing temperature and perform the same processing as described above (step S11). S8
To S11).

At the end of the receiving operation or the copying operation in step S11, the CPU 2
Then, a light-off command is output to No. 2 and the power supply to the fixing heater 12 is stopped, and then the recording process is terminated (step S12).

The setting of the duty and the control of the energization of the fixing heater 12 based on the set duty are performed as shown in FIG. 4 to FIG. 8 as a temperature difference between the fixing temperature and the temperature of the fixing roller 28 and a temperature change of the fixing roller 28. Based on the tendency, the input voltage value of the fixing heater 12, the environmental temperature of the fixing roller 28, the temperature rising tendency of the fixing roller 28, and the like.
U2 is performed by interrupt processing from the timer 9.

First, the case where the interruption energization control process for the fixing heater 12 is performed based on the temperature difference between the fixing temperature and the temperature of the fixing roller 28 will be described below with reference to FIG.

When an interrupt is generated from the timer 9 based on the clock, the CPU 2 calculates a temperature difference between the detected temperature from the thermistor 10 and the fixing temperature (step T1).
The on-period and off-period corresponding to the calculated temperature difference, that is, the on / off duty of the fixing heater 12 is represented by R
The data is read from the data table stored in OM3 and set (step T2).

After setting the duty, the CPU 2 outputs a lighting command to the fixing heater 12 to
2 (step T3), and based on the clock from the timer 9, it is checked whether or not the set lighting period has elapsed (step T4).

In step T4, when the lighting period has elapsed,
The CPU 2 outputs a turn-off instruction to the fixing heater 12,
The energization of the fixing heater 12 is stopped (step T
5) It is checked whether or not the light-off period has elapsed (step T6).

In step T6, when the light-off period has elapsed,
The CPU 2 ends the interrupt energization control process, and returns to step S11 of the recording process, which is the main process shown in FIG.

As described above, the light-on period and the light-off period of the fixing heater 12 are set based on the detected temperature, that is, the temperature difference between the current temperature of the fixing roller 28 and the fixing temperature as a control target. The power supply to the fixing heater 12 is finely controlled by the period and the light-off period,
Can be heated.

As a result, the fixing roller 28 can be quickly and appropriately controlled to the fixing temperature while further suppressing the temperature ripple and the overshoot, thereby improving the fixing property and improving the image quality. Can be.

Next, based on the temperature difference between the fixing temperature and the temperature of the fixing roller 28 and the temperature change tendency of the fixing roller 28,
The case of performing the interrupt energization control process for the fixing heater 12 will be described below with reference to FIG.

When an interrupt is generated from the timer 9 based on the clock, the CPU 2 calculates the temperature difference between the detected temperature from the thermistor 10 and the fixing temperature (step T1).
1) Next, the temperature change tendency of the detected temperature is determined (step T12).

Here, the CPU 2 sequentially operates the thermistor 1
The detected temperature input from 0 is stored in the RAM 4 for a predetermined period of time, and the detected temperature based on the latest detected temperature input this time and the detected temperature for the predetermined period stored in the RAM 4, that is, the temperature of the fixing roller 28. Determine the change tendency.

Next, the CPU 2 reads from the data table stored in the ROM 3 the lighting period and the lighting period (duty of turning on / off the fixing heater 12) corresponding to the calculated temperature difference and the change tendency of the detected temperature. The setting is performed (step T13), a lighting command is output to the fixing heater 12, and the fixing heater 12 is energized (step T1).
4).

When the fixing heater 12 is turned on, the CPU
2 checks whether or not the set lighting period has elapsed based on the clock from the timer 9 (step T15), and when the lighting period has elapsed, outputs a turn-off command to the fixing heater 12 and sends it to the fixing heater 12. Is stopped (step T16), it is checked whether or not the light-off period has elapsed (step T17).

When the light-off period has elapsed in step T17, the CPU 2 terminates the interrupt energization control process and proceeds to step S11 of the recording process, which is the main process shown in FIG.
Return to

As described above, the detected temperature, that is, the temperature difference between the current temperature of the fixing roller 28 and the fixing temperature which is the control target, and the change tendency of the detected temperature, that is, the fixing roller 2
8 based on how fast the temperature changes
The lighting period and the light-off period of the fixing heater 12 are set, and the energization to the fixing heater 12 is finely controlled by the lighting period and the light-off period, so that the fixing roller 28 can be heated.

As a result, the fixing roller 28 can be quickly and appropriately controlled to the fixing temperature while the temperature ripple and the overshoot are more appropriately suppressed, so that the fixing property is further improved and the image quality is improved. It can be further improved.

Next, a case where the interruption energization control process for the fixing heater 12 is performed based on the temperature difference between the fixing temperature and the temperature of the fixing roller 28 and the input voltage value to the fixing heater 12 will be described with reference to FIG. This will be described below.

When an interrupt is generated from the timer 9 based on the clock, the CPU 2 calculates a temperature difference between the detected temperature from the thermistor 10 and the fixing temperature (step T2).
1) Next, the heater input voltage value, that is, the voltage value of the input voltage of the power supply supplied to the fixing heater 12 is detected (step T22).

Here, the CPU 2 detects the input voltage value of the heater by the input voltage detection unit 14 and
4 is detected based on a digital voltage signal input from the control circuit 4.

Next, the CPU 2 reads from the data table stored in the ROM 3 and sets the lighting period and the lighting period (duty of turning on / off the fixing heater 12) corresponding to the calculated temperature difference and the heater input voltage value. Then, a lighting command is output to the fixing heater 12 to energize the fixing heater 12 (step T2).
4).

When the fixing heater 12 is turned on, the CPU
2 checks whether the set lighting period has elapsed based on the clock from the timer 9 (step T25), and when the lighting period has elapsed, outputs a turn-off command to the fixing heater 12 and Is stopped (step T26), it is checked whether or not the light-off period has elapsed (step T27).

When the light-off period has elapsed in step T27, the CPU 2 terminates the interrupt energization control process and proceeds to step S11 of the recording process, which is the main process shown in FIG.
Return to

As described above, based on the detected temperature, that is, the temperature difference between the current temperature of the fixing roller 28 and the fixing temperature which is the control target, and the input voltage value to the fixing heater 12,
The lighting period and the light-off period of the fixing heater 12 are set, and the energization to the fixing heater 12 is finely controlled by the lighting period and the light-off period, so that the fixing roller 28 can be heated.

Therefore, in response to a change in the input voltage of the power supply supplied to the fixing heater 12,
Power supply to the fixing roller 28 while controlling temperature ripple and overshoot more appropriately.
Can be quickly and appropriately controlled to the fixing temperature.

As a result, the fixability can be further improved, and the image quality can be further improved.

Next, FIG. 7 shows a case in which interrupt energization control to the fixing heater 12 is performed based on the temperature difference between the fixing temperature and the temperature of the fixing roller 28 and the outside air temperature (the environmental temperature of the fixing roller 28). The following is a description based on this.

When an interrupt is generated from the timer 9 based on the clock, the CPU 2 calculates the temperature difference between the detected temperature from the thermistor 10 and the fixing temperature (step T3).
1) Next, the outside air temperature, that is, the environmental temperature around the fixing roller 28 is detected (step T32).

Here, the CPU 2 detects the outside air temperature by the outside air temperature detection sensor 17 and the temperature detection signal digitally converted by the A / D conversion section 18.

Next, the CPU 2 stores the calculated temperature difference and the outside air temperature, that is, the lighting period and the light-off period (on / off duty of the fixing heater 12) corresponding to the environmental temperature of the fixing roller 28 in the ROM 3. The data is read from the stored data table and set (step T33), a lighting command is output to the fixing heater 12, and the fixing heater 12 is energized (step T34).

When the fixing heater 12 is turned on, the CPU
2 checks whether or not the set lighting period has elapsed based on the clock from the timer 9 (step T35), and when the lighting period has elapsed, outputs a turn-off command to the fixing heater 12 and sends it to the fixing heater 12. Is stopped (step T36), it is checked whether or not the light-off period has elapsed (step T37).

When the light-off period elapses in step T37, the CPU 2 terminates the interrupt energization control process and proceeds to step S11 of the recording process, which is the main process shown in FIG.
Return to

As described above, the fixing heater 12 is turned on based on the detected temperature, that is, the temperature difference between the current temperature of the fixing roller 28 and the fixing temperature which is the control target, and the outside air temperature which is the environmental temperature of the fixing roller 28. A lighting period and a light-off period are set.
The fixing roller 28 can be heated by finely controlling the power supply to the fixing roller 28.

Therefore, the power supply to the fixing heater 12 can be controlled in consideration of the ambient temperature of the fixing roller 28, and the fixing roller 28 can be quickly moved while suppressing the temperature ripple and the overshoot more appropriately. In addition, the fixing temperature can be appropriately controlled.

As a result, the fixing property can be further improved, and the image quality can be further improved.

Next, a case where the interruption energization control process for the fixing heater 12 is performed based on the temperature difference between the fixing temperature and the temperature of the fixing roller 28 and the rising tendency of the surface temperature of the fixing roller 28 will be described with reference to FIG. This will be described below.

When an interrupt is generated from the timer 9 based on the clock, the CPU 2 calculates the temperature difference between the detected temperature from the thermistor 10 and the fixing temperature (step T4).
1) Next, the tendency of the surface temperature of the fixing roller 28 to rise is determined (step T42).

Here, the CPU 2 stores the detected temperature inputted from the thermistor 10 in the RAM 4 for a predetermined period after the energization of the fixing heater 12 is started, and stores the latest detected temperature inputted this time and the RAM 4. The rising tendency of the surface temperature of the fixing roller 28 is determined from the detected temperature for the predetermined period.

Next, the CPU 2 stores in the ROM 3 the lighting period and the light-off period (duty of turning on / off the fixing heater 12) corresponding to the calculated temperature difference and the rising tendency of the surface temperature of the fixing roller 28. The setting is read out from the table (step T43), a lighting instruction is output to the fixing heater 12, and the fixing heater 12 is energized (step T44).

When the fixing heater 12 is turned on, the CPU
2 checks whether the set lighting period has elapsed based on the clock from the timer 9 (step T435).
After turning off the power to the fixing heater 12 (step T46), it is checked whether the light-off period has elapsed (step T47).

When the light-off period has elapsed in step T47, the CPU 2 terminates the interrupt energization control process and proceeds to step S11 of the recording process, which is the main process shown in FIG.
Return to

As described above, the lighting period of the fixing heater 12 is determined based on the detected temperature, that is, the temperature difference between the current temperature of the fixing roller 28 and the fixing temperature which is the control target, and the tendency of the surface temperature of the fixing roller 28 to rise. And the light-off period, and the fixing heater 1
2 can be finely controlled and the fixing roller 28 can be heated.

Therefore, it is possible to control the power supply to the fixing heater 12 in consideration of the rising tendency of the surface temperature of the fixing roller 28, and to control the fixing roller 28 while suppressing the temperature ripple and the overshoot more appropriately. The fixing temperature can be more quickly and appropriately controlled.

As a result, the fixing property can be further improved, and the image quality can be further improved.

Although the invention made by the inventor has been specifically described based on the preferred embodiments, the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the gist of the invention. Needless to say, it can be changed.

For example, in the above embodiment, the case where the present invention is applied to the facsimile apparatus 1 has been described.
2, the present invention can be applied to general recording apparatuses having a fixing device for fixing toner onto recording paper, for example, a laser printer, a copying machine, and the like.

Further, in the above embodiment, in the interruption energization control processing shown in FIGS. 5 to 8, the temperature change tendency of the fixing roller 28, the input voltage value to the fixing heater 12, the outside air temperature or the fixing roller 28 The rising tendency of the surface temperature is individually combined with the temperature difference between the detected temperature and the fixing temperature to set the lighting period and the extinguishing period of the fixing heater 12 to control the energization. It is not limited to the combination with the temperature difference from the temperature.
The energization control may be performed by setting a lighting period and an extinguishing period of No. 2 or by appropriately combining these to set an energizing period and an extinguishing period of the fixing heater 12 and performing energization control. Good.

Further, in the above-described embodiment, the temperature control of the fixing roller 28 is performed by controlling the lighting period and the turning-off period of the fixing heater 12, but the present invention is not limited to this. The current value and the voltage value to be controlled may be controlled to control the temperature of the fixing heater.

[0108]

According to the fixing device of the first aspect of the present invention, the rising slope of the temperature of the fixing member differs for each fixing member.
It is possible to control the power supply to the fixing heater in consideration of
Thus , the fixing roller can be appropriately controlled to the fixing temperature while preventing temperature ripple and overshoot. As a result, fixability can be improved, and image quality can be improved.

According to the fixing device of the second aspect,
Based on the temperature difference between the fixing roller temperature and the fixing temperature,
Electricity to the heater can be finely controlled,
More precise temperature control can be performed.

According to the fixing device of the third aspect of the present invention,
To the fixing heater, taking into account the tendency of the fixing member to change in temperature
Control of the current flowing through the fixing member.
Accordingly, finer temperature control can be performed.

According to the fixing device of the fourth aspect of the present invention,
Considering changes in the input voltage value to the fixing heater,
Power supply control to the heater can be performed,
Detailed temperature control can be performed.

According to the fixing device of the fifth aspect,
Considering the ambient temperature of the fixing roller,
Energization control can be performed, and finer fixing member
Temperature control can be performed.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a facsimile apparatus to which an embodiment of a fixing device according to the present invention is applied.

FIG. 2 is a schematic configuration diagram of a plotter unit in FIG. 1;

FIG. 3 is a flowchart illustrating a recording process performed by the facsimile apparatus of FIG. 1;

FIG. 4 is a flowchart showing interrupt energization control processing based on a temperature difference between a detected temperature and a fixing temperature by the facsimile apparatus of FIG. 1;

5 is a flowchart showing interrupt energization control processing by the facsimile apparatus of FIG. 1 based on a temperature difference between a detected temperature and a fixing temperature and a heater input voltage.

FIG. 6 is a flowchart showing interrupt energization control processing based on a temperature difference between a detected temperature and a fixing temperature and a tendency of the detected temperature to change by the facsimile apparatus of FIG. 1;

7 is a flowchart showing interrupt energization control processing by the facsimile apparatus of FIG. 1 based on a temperature difference between a detected temperature and a fixing temperature and an outside air temperature.

8 is a flowchart showing interrupt energization control processing by the facsimile machine of FIG. 1 based on a temperature difference between a detected temperature and a fixing temperature and a rising tendency of a surface temperature of a fixing roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Facsimile apparatus 2 CPU 3 ROM 4 RAM 5 Communication part 6 Reading part 7 Operation display part 8 Plotter part 9 Timer 10 Thermistor 11 A / D conversion part 12 Fixing heater 13 Output port 14 Input voltage detection part 15 Drive control part 16 Laser control Unit 17 outside air temperature detection unit 18 A / D conversion unit 20 bus

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (5)

(57) [Claims] A fixing device for fixing a toner transferred to a recording sheet to a recording sheet by a fixing member heated to a predetermined fixing temperature by a fixing heater, wherein a temperature detecting means for detecting a temperature of the fixing member; Starting the energization of the fixing heater and then detecting the temperature
Storage means for storing the detected temperature for a predetermined period detected by the stage
The fixing member based on the stored detected temperature for a predetermined period.
Surface temperature rising tendency of the
A lighting period in which the fixing heater is energized and an extinguishing period in which energization to the fixing heater is stopped are set with the rising tendency as a determining factor, and the fixing heater is set based on the set lighting period and the extinguishing period. And a control unit for controlling power supply to the fixing member to control the temperature of the fixing member to the fixing temperature. 2. The control means calculates a temperature difference between a temperature detected by the temperature detection means and the fixing temperature, and calculates the temperature difference.
2. The fixing device according to claim 1, wherein one of the determination factors for setting the lighting period and the light-off period is used. 3. The control means according to claim 1 , wherein said control means detects a temperature of said temperature detecting means.
Determining the temperature change tendency of the fixing member based on the temperature,
2. The temperature change tendency is one of the determination factors for setting the lighting period and the light-off period.
Or the fixing device according to claim 2. Wherein said fixing device is input to the fixing heater
Voltage control means for detecting a force voltage value , wherein the control means uses a detection result of the voltage detection means as one of the determination factors for setting the lighting period and the light-off period. the fixing device according to any one of claims 1 to claim 3. 5. The fixing device according to claim 1 , wherein at least the fixing member is provided.
Environmental temperature detecting means for detecting the ambient temperature around
And wherein the control unit sets the detection result of the environmental temperature detection unit as one of the determination factors for setting the lighting period and the extinguishing period. 5. The fixing device according to any one of 4 to 4.