JPH0713461A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent uneven fixing and offset under fixed temperature distribution by varying the speed of a roller in accordance with the rising rate and the lowering rate of the surface temperature of a fixing roller in a fixing device differen in the heat capacity and the radiated heat quantity of the fixing roller and a pressure roller from each other. CONSTITUTION:When the surface temperature of the fixing roller is fixing standby temperature, a CPU 13 transmits a start signal to a timer circuit 20. In the case a printing signal is generated in a specified time, the speed of a motor is kept constant speed, and when the surface temperature of the fixing roller 1 becomes the target temperature of fixing, fixing speed is varied to processing speed in accordance with the kind of a recording material. After specified fixing processing is performed, the lowering rate of the surface temperature of the fixing roller is measured and stored in a RAM inside the CPU 13. In the case the printing signal is not inputted continuously, a heater 3 stops heating, and data on the lowering rate of the surface temperature of the fixing roller stored in the RAM is read out and the rotating speed of a DC motor 9 is varied by referring to a table stored inside the CPU 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an image forming apparatus such as a copying machine or a laser beam printer which employs an electrophotographic system.

[0002]

2. Description of the Related Art Next, a conventional technique will be described.

<Prior Art Example 1> Conventionally, for example, in a temperature control system of a roller type heat fixing device using a fixing roller having a heater and a pressure roller, power saving and improvement of heat-deteriorated parts or quick fixing operation can be achieved. In order to do so, a plurality of target temperatures are set according to the state of the fixing device, the temperature is controlled at a fixing waiting temperature lower than the fixing target temperature after the power is turned on, and when the fixing start signal is input, the waiting period is changed. The temperature is controlled to shift from the temperature to the fixing target temperature, the temperature is shifted to the waiting temperature again at the end of the predetermined fixing operation, and the above control is repeated.

In this type of fixing device, due to the difference in heat supply method between the fixing roller and the pressure roller and the difference in heat capacity, after the power is turned on or after the transfer material such as paper is passed during fixing, Since the pressure roller supplies heat with a small contact area with the fixing roller that has a built-in heater, heat transfer from the fixing roller to the pressure roller does not occur smoothly, and from this state the target fixing temperature is fixed. When the roller pair is rotated and a predetermined fixing is carried out after the shift to, the surface temperature of the fixing roller is rapidly cooled by the amount of heat absorbed from the fixing roller by the pressure roller, resulting in fixing failure. If paper is continuously fed during a predetermined fixing operation, the surface temperature of the fixing roller and the pressure roller is reduced because the heat is absorbed by the paper, but the heat distribution of the fixing roller and the pressure roller is different because the heat is absorbed differently. Are not uniform and still cause defective fixing.

As a measure against such a drawback, after the power is turned on, the roller is rotated to a target fixing temperature, and after the predetermined fixing operation is performed, the roller is stopped and the next fixing operation is performed at the fixing waiting temperature. There has been proposed a method of performing temperature control so as to wait. <Prior art example 2> Conventionally, in a thermal fixing device of a recording apparatus, a fixing roller is heated by a heating element, for example, a heater, and recording paper is passed through the roller to fix the fixing roller. A temperature detecting device such as a thermistor is brought into contact with this roller to detect the surface temperature of the fixing roller, and the heater of the fixing roller is driven based on this information to keep the fixing roller at a predetermined temperature.

<Prior Art 3> Conventionally, a heat roller fixing device is composed of a heat roller having a heating means and a pressure roller in pressure contact with the heat roller, and in order to maintain good fixing, the surface of the heat roller is fixed. It is proposed that the temperature can be controlled to a predetermined temperature. The thermistor is brought into contact with the roller surface for temperature sensing for controlling the roller surface to a predetermined temperature.

Consider this with reference to FIGS. Thirty
Reference numeral 1 denotes a heating roller, which has a heater 302 built in the center thereof, and a thermistor 303 serving as a temperature detecting means at the upper portion of the heating roller 3
01 is pressed against and is driven to rotate by the rotational drive of the heating roller 301. The paper 305 passes between the rollers 301 and 304 with the toner holding surface facing upward, and the toner is fused and fixed.

The surface temperature of the heating roller 301 is detected by the thermistor 303 which is in contact with the heating roller 301, and the current temperature is compared with the set temperature in the microcomputer 310 to make a judgment. A constant temperature is maintained by sending a blinking signal and controlling the heater on / off by the heater control circuit 311.

<Prior Art Example 4> In a conventional electrophotographic printer, the power supply is independent of the host computer. When the user uses the printer, it is often used to manually turn on the printer.

Next, as the structure of the fixing device, toner or paper powder adheres to the surface of the temperature detecting element to wear the releasing resin layer on the surface of the fixing roller, resulting in black streaks on the image. In order to avoid problems, a fixing device having a structure in which the temperature detecting element is brought into contact with the end portion of the fixing roller has been proposed. (FIG. 30 (A)) Further, as shown in FIG. 30 (B), the structure of the heater is such that the light distribution can be maintained at 70% or more at the temperature detecting element position with respect to 100% in the central portion in the longitudinal direction. There is an example using a flat type heater. By doing so, it is possible to reduce the temperature drop in the sheet passing portion on the fixing roller, prevent the fixing failure, and suppress the temperature rise in the non-sheet passing portion.

<Prior Art Example 5> Conventionally, in an electrophotographic printer engine, when the power is turned on, the engine mechanism control unit energizes the halogen heater of the fixing device to reach the temperature required for fixing the toner on the paper. Then, if other printable conditions are satisfied, R is in the printable state.
Set the DY signal to true.

Then, when the PRNT signal for instructing the print start is received from the printer controller, the vertical synchronization signal request VSREQ signal is output within a predetermined time, the vertical synchronization signal VSYNC signal is received from the printer controller, and a predetermined time after that, from the engine. An image is formed on the photosensitive drum by a laser or the like by the image signal VDO output from the printer controller in synchronization with the output horizontal synchronization signal BD, toner is placed on the photosensitive member, and the image is transferred onto paper. It is fixed on the paper by the fixing roller.

In such a series of operations, the engine mechanism controller has always controlled the temperature of the fixing device within a constant temperature range except when a jam occurs, when the door is open, when it is inactive, and when there is a failure.

<Conventional Example 6> FIG. 38 is a sectional view of a conventional heat roller type fixing device.

The fixing roller 601 comprises a hollow cored bar made of aluminum, iron or the like and a heater 602 such as a halogen lamp placed inside the hollow core. The heater 602 heats the fixing roller 601. The pressure roller 603 is
An outer periphery of a core metal 604 made of iron or stainless steel is covered with an elastic body 605 having releasability such as silicone rubber. The fixing roller 601 and the pressure roller 603 are brought into contact with each other with a predetermined pressure by an urging means such as a spring (not shown), and are rotationally driven in the arrow direction.

Reference numeral 606 denotes a temperature sensitive element such as a thermistor which is in contact with the surface of the fixing roller 601 and detects the surface temperature of the fixing roller 601. The temperature control circuit controls the energization of the heater 602 according to the temperature detected by the temperature sensitive element 606, and the surface temperature of the fixing roller 601 is automatically controlled to a predetermined heat fixing temperature. Reference numeral 607 denotes a separation claw that separates the transfer material P from the surface of the fixing roller 601. The separation edge 607 is arranged such that the leading edge portion is in contact with the surface of the fixing roller 601 with an appropriate pressure.

Reference numeral 608 denotes a cleaner such as felt which is brought into pressure contact with the surface of the fixing roller 601 and wipes and removes the toner tc, paper dust and the like adhering to the surface of the fixing roller 601. 609
Is a metal bottom plate of the fixing device, and 610 is a transfer material entrance guide, and the bottom plate 609 is bent upward and is attached and supported on the front wall.

Further, 611a and 611b are transfer material outlet rollers, and the rotary shafts of these rollers are attached to the rear wall. The transfer material P that has entered the fixing device through the entrance guide 610 enters the nip portion between the fixing roller 601 and the pressure roller 603 which are rotationally driven in pressure contact with each other, and both rollers 601 and 603 rotate. It will pass with it. In the process of passing through the nip, the unfixed toner image ta on the transfer material P is fixed as a permanently fixed image tb by heat and pressure.

The transfer material P, which has passed through the nip portion of the rollers 601, 603 and has undergone image fixing, has its leading end separated from the surface of the fixing roller 601 by the separation claw 607, and the exit roller 61.
It is discharged to the outside of the fixing device through 1a and 611b.

<Conventional Example 7> FIG. 47 is a sectional view of a conventional heat roller type fixing device.

The fixing roller 701 is a hollow cored bar made of aluminum, iron or the like, and a heater 702 such as a halogen lamp is placed inside the hollow cored bar, and the heater 702 heats the fixing roller 701. The pressure roller 703 is
An outer periphery of a core metal 704 made of iron or stainless steel is covered with an elastic body 705 having releasability such as silicone rubber. The fixing roller 701 and the pressure roller 703 are brought into contact with each other with a predetermined pressure by a biasing means such as a spring (not shown), and are rotationally driven in the arrow direction.

Reference numeral 706 is a temperature sensitive element such as a thermistor which is in contact with the surface of the fixing roller 701, and detects the surface temperature of the fixing roller 701. The temperature control circuit controls the energization of the heater 702 according to the temperature detected by the temperature sensitive element 706, and the surface temperature of the fixing roller 701 is automatically controlled to a predetermined thermal fixing temperature. Reference numeral 707 denotes a separation claw that separates the transfer material P from the surface of the fixing roller 701, and the tip edge portion is disposed so as to contact the surface of the fixing roller 701 with an appropriate pressure.

Reference numeral 708 denotes a cleaner such as ferrit which is brought into pressure contact with the surface of the fixing roller 701 and wipes and removes the toner tc, paper dust and the like adhering to the surface of the fixing roller 701. 709
Is a metal bottom plate of the fixing device, and 710 is a transfer material entrance guide. The bottom plate 709 is bent upward and is attached to and supported by the front wall.

Further, 711a and 711b are transfer material outlet rollers, and the rotary shafts of these rollers are attached to the rear wall. The transfer material P that has entered the fixing device through the entrance guide 710 enters into the nip portion between the fixing roller 701 and the pressure roller 703 that are rotationally driven in pressure contact with each other, and both rollers 701 and 703 rotate. It will pass with it. In the process of passing through the nip, the unfixed toner image ta on the transfer material P is fixed as a permanently fixed image tb by heat and pressure.

The transfer material P, which has passed through the nip portion of the rollers 701 and 703 and has undergone image fixing, has its leading end separated from the surface of the fixing roller 701 by the separation claw 707, and then exit roller 71.
It is discharged to the outside of the fixing device through 1a and 711b.

[0026]

However, in the prior art example 1, in a color fixing device or the like in which the amount of toner is large, in order to adopt the roller type heat fixing system, a sufficient amount of heat is applied to the toner. The pressure roller needs to have an appropriate nip amount, and the fixing roller and the pressure roller do not always have the same material and the same thickness due to the fixing conditions such as giving gloss to the recording material such as OHP. That is, since the heat capacity and the heat radiation amount are often different from each other, under the condition that only the fixing roller side is heated, the heat distribution between the fixing roller and the pressure roller becomes uneven, and uneven fixing may occur.

Further, in Conventional Example 2, since the temperature detecting device was brought into contact with the rotating fixing roller, the fixing roller was damaged. These scratches leave scratch marks on the recording paper, which is a drawback that the image quality is deteriorated.

Further, a developer such as toner adheres to the scratches on the fixing roller, which hinders the detection of the correct fixing roller surface temperature, and in the worst case, a fire or smoke may occur.

Further, in the above-mentioned conventional example 3, since the temperature is detected by the thermistor which is in contact with the heating roller, when the heating roller rotates, the heating roller is worn and the life is shortened.

When a bias voltage is applied to the roller in order to prevent the toner from adhering to the roller, dielectric breakdown may occur between the roller and the thermistor, and surge current may flow. As a countermeasure against this, it is possible to change the thermistor from the contact type to the non-contact type with respect to the heating roller.However, when a space is opened between the heating roller and the thermistor as the non-contact type, the temperature detected depends on the distance of this space. Since it changes, there is a defect that accurate temperature detection becomes difficult.

Further, in the case of the apparatus of Conventional Example 4, when the printer is left in a power-off state for a long time, and then the printer is turned on, and printing is immediately performed,
Since the heater 402 is energized and controlled from the state where the surface of the fixing roller 401 is cold to the print controlled temperature,
Since the temperature difference between the fixing roller surface temperature and the controlled temperature is large, the overshoot in the temperature detecting element 405 becomes large.

In particular, up to the first few sheets, the surface temperature of the central portion of the fixing roller becomes higher by about 30 ° C. than the temperature of the temperature detecting element, so that heat is taken away by passing the sheet, and the temperature detecting element is heated. This state continues until the temperature is almost the same.

If the surface temperature of the central portion of the fixing roller is higher than the temperature of the temperature detecting element by 30 ° C., the amount of reverse crown of the fixing roller decreases due to thermal expansion, and as a result, the effect of extending the transfer material in the axial direction is weakened, and the solid image is solid When a black image or the like is printed, there is a problem that "paper wrinkles" are likely to appear in the central portion of the image by the first few sheets. This "paper wrinkle" has a feature that when the transfer material is left in a high temperature and high humidity environment, the transfer material absorbs moisture so that it is particularly easy to handle.

In the prior art example 4, when the print signal is not received for a long time, or when the print cannot be performed and it takes a long time to be ready for printing, the fixing device is not performed although the fixing is not performed. However, there is a drawback that a large amount of electric power is consumed to keep the temperature within a predetermined temperature range.

In the fixing device of Conventional Example 6, the temperature sensitive element 606 is generally brought into contact with the fixing roller 601 by using a spring material or the like. This method improves the accuracy of temperature detection by the temperature sensitive element 606, but on the other hand, due to the durability, the fixing roller 601 is often worn at the abutting portion and is scratched, which causes a problem in the fixing performance.

A means for preventing this is shown in FIG.
As shown in FIG. 9, there is a method in which the temperature sensitive element 606 and the fixing roller 601 are not in contact with each other and are opposed to each other with a slight gap 1.

In the figure, the temperature sensitive element 606 is a support base 61.
2, and is fixed to the side plate 616 by the top plate 613.
The fixing roller 601 includes a bearing 615 and a bearing 6.
It is attached to the side plate 616 through 14.

According to this method, it is possible to prevent scratches due to the contact between the fixing roller 601 and the temperature sensitive element 606, but the accuracy of temperature detection deteriorates, and the surface temperature T _r of the fixing aura 601 and the temperature sensitive element 606. A deviation occurs in the temperature T _s in the vicinity. That is, it was found that T _r > T _s .

In order to prevent this, it is necessary to make the gap 1 small, but the assembling accuracy, the roundness of the fixing roller 601 and the expansion due to heat, and the temperature sensitive element 606 due to the toner adhering to the surface of the fixing roller 601. There is a limit to the reduction of the gap l in consideration of the contamination of ΔT = T
_This means that the temperature must be detected by anticipating _r −T _s in advance.

However, when such a detecting method is performed, ΔT becomes a stable value after the fixing roller 601 has been sufficiently warmed, but the fixing roller 601 is energized to heat the heater 602 from a cold state. In such a case, as shown in FIG. 40, the speed of increase in the temperature around the temperature sensitive element 606 is slower than the speed of increase in the surface temperature of the fixing roller 601, and ΔT ′ becomes large.

As a result, the following inconvenience occurs.

(1) When the temperature sensitive element is an element such as a thermistor for controlling the temperature of the fixing roller 601, the temperature is detected to be lower than the actual value during the control after the power is turned on. , Fixing roller 6 at a temperature higher than necessary
The temperature of 01 is controlled.

(2) When the temperature sensitive element is an element such as a thermoswitch for preventing overheating runaway of the fixing roller 601, overheating runaway during control after power is turned on cannot be sufficiently prevented.

Further, in the fixing device of Conventional Example 7, the temperature sensitive element 706 is generally brought into contact with the fixing roller 701 by using a spring material or the like. Although this method improves the accuracy of temperature detection by the temperature sensitive element 706, on the other hand, there is often a problem that the fixing roller 701 is worn at the abutting portion due to the durability and is scratched, thereby impairing the fixing performance.

A means for preventing this is shown in FIG.
As shown in FIG. 8, there is a method in which the temperature sensitive element 706 and the fixing roller 701 are not in contact with each other and face each other with a slight gap l.

In the figure, the temperature sensitive element 706 is a support base 71.
2, the top plate 713 is fixed to the side plate 716.
The fixing roller 701 includes a bearing 715 and a bearing 7.
It is attached to the side plate 716 through 14.

According to this method, it is possible to prevent scratches due to contact between the fixing roller 701 and the temperature sensitive element 706, but the accuracy of temperature detection deteriorates, and the surface temperature _Tr of the fixing roller 701 and the temperature sensitive element 706. A deviation occurs in the temperature T _s in the vicinity of. That is, it was found that Tr> T _s .

To prevent this, it is necessary to reduce the gap l, but the assembling accuracy, the roundness of the fixing roller 701 and expansion due to heat, and the temperature sensitive element 706 due to the toner adhering to the surface of the fixing roller 701. Considering contamination and the like, there is a limit in reducing the gap l, and ΔT = T
_This means that the temperature must be detected by anticipating _r −T _s in advance.

However, when such a detection method is performed, ΔT becomes a stable value after the fixing roller 701 has been sufficiently warmed, but the fixing roller 701 is energized to heat it when it is cold. In such a case, as shown in FIG. 49, the speed of increase in the temperature around the temperature sensitive element 706 becomes slower than the speed of increase in the surface temperature of the fixing roller 701, and ΔT ′ becomes large.

As a result, the following problems occur.

(1) If the temperature sensitive element is an element such as a thermistor for controlling the temperature of the fixing roller 701, the temperature is detected to be lower than the actual value during the control after the power is turned on. Fixing roller 70 at a higher temperature than necessary
It controls the temperature of 1. (2) When the temperature-sensitive element is an element such as a thermoswitch for preventing overheating runaway of the fixing roller 701, overheating runaway during control after power is turned on cannot be sufficiently prevented.

It is an object of the present invention to solve the various problems described above and to provide a fixing device which operates well.

[0053]

Means for Solving the Problems The means for solving the problems according to the present invention are as described in each claim of the claims. An outline of the solving means and the operation is as follows.

According to the first to third aspects, the driving means for driving the fixing roller, the heater heating means for heating the heater, the temperature detecting means for detecting the fixing roller surface temperature, and the fixing roller surface temperature detecting means. Calculation means for calculating the rising characteristics of the fixing roller surface temperature and the falling characteristics due to heat radiation to the recording material, variable speed means for changing the driving means for driving the fixing roller, and roller rotation by the fixing roller temperature characteristics calculating means. It has a reference means for making a table reference for changing the speed change means, and by appropriately changing the roller rotation speed according to the surface temperature of the fixing roller, the heat deviation between the fixing roller and the pressure roller is eliminated and the fixing unevenness is suppressed. It is characterized by that.

According to the fourth to tenth aspects, the rotation stop of the fixing roller is controlled, the temperature detecting device is brought into non-contact when the fixing roller is rotating, and the temperature detecting device is brought into contact with the fixing roller when the fixing roller is stopped.
This defect is eliminated by controlling the temperature of the fixing roller.

According to the eleventh and twelfth aspects, by providing the heating roller with the non-contact type thermistor and the movable contact type thermistor, it is possible to accurately control the temperature by the non-contact type thermistor.

According to the thirteenth to fifteenth aspects, before the printer starts the printing operation, the heater of the fixing device is energized and the surface of the fixing roller is preheated before the printing operation. The temperature difference from the roller surface temperature is small and the overshoot is small.

As a result, it is possible to prevent the problem of occurrence of "paper wrinkles" in the central portion of the image such as solid black images up to the first few sheets after printing.

According to the sixteenth to eighteenth aspects, the engine mechanism control section is provided with means for detecting the predetermined time, so that the printing is performed at the time when the predetermined time elapses from the time when the unprintable state such as paper out or failure is detected. When the disabled state continues, the energization of the fixing heater is stopped, and the fixing device is controlled to a predetermined temperature when the printing is possible except for the fixing device.

When the print start signal is not received at the time when a predetermined time has elapsed from the time when the print is ready, the power supply to the heater of the fixing device is stopped until the print start signal is received.

Further, a means for detecting ON / OFF of the control method is provided, and the control method is turned ON / OFF from the outside.

According to the nineteenth aspect, a pair of heat fixing means and pressure means for fixing the image supporting member supporting the toner image on the surface through the nip portion, and a pair of heat fixing means near the surface of the heat fixing means. In a heat fixing device having a temperature detecting means arranged to face the heat fixing means in a non-contact state to detect the temperature, and a supporting member for supporting the temperature detecting means, the heat fixing means and the temperature When the closest distance to the detecting means is l ₁ and the closest distance to the heat fixing means in the vicinity of the temperature detecting means of the supporting member is l ₂ , l ₂ ≤l
_By being configured to be ₁ , the responsiveness of the temperature detecting means to the temperature change of the thermal fixing means is improved.

According to the twentieth aspect, a pair of heat fixing means and pressure means for fixing the image supporting member supporting the toner image on the surface through the nip portion, and a pair of heat fixing means near the surface of the heat fixing means. In a heat fixing device having a temperature detecting means arranged to face the heat fixing means in a non-contact state so as to detect the temperature, and a support member for supporting the temperature detecting means, the temperature detection of the support member is performed. By holding a heat-resistant seal material in the vicinity of the fixing means and bringing it into contact with the fixing means, the space in the vicinity of the temperature detecting means is substantially cut off from the outside, thereby changing the temperature of the heat fixing means. The responsiveness of the temperature detecting means to the is improved.

[0064]

EXAMPLES Examples of the present invention will be described below.

First, first and second embodiments according to claims 1 to 3 will be described with reference to FIGS.

FIG. 1 is a main configuration diagram of the present invention, showing a configuration diagram of an electrophotographic printer and a circuit diagram around a fixing device.

The mechanical structure will be described. Reference numerals 1 and 2 denote a fixing roller and a pressure roller that rotate in pressure contact with each other. A halogen heater 3 is arranged inside the center of the fixing roller 1 to supply heat. Numerals 4 and 4'are guides which are arranged to make paper feeding and paper discharging smooth. Fusing roller 1
The felt 6 impregnated with silicone of the oil sump 5 comes into contact with the surface of the oil reservoir 5 to apply oil.

Reference numeral 7 is a gear connected to the pressure roller 2, and torque is transmitted by driving the DC motor 9 interposed by the belt 8, and the fixing roller 1 and the pressure roller 2 are pressed against each other in the illustrated direction. It is rotating. Reference numeral 10 denotes a thermistor arranged close to the surface of the fixing roller, which inputs a voltage (GND and VCC are divided by the resistor 11) corresponding to the detected temperature to the A / D converter 12 to convert it into a digital signal and to the CPU 13. Sending out.

The DC motor 9 is driven by the motor control circuit 14, and the CPU 13 outputs a motor drive signal for changing whether or not to drive the motor and the rotation speed.
The rotary encoder 17 is used to control the motor rotation speed to CP.
The U13 monitors and changes the pulse signal so as to change the rotation speed according to the fixing roller surface temperature data input from the A / D converter 12 and the print signal input from the I / F circuit 15.

Reference numeral 20 denotes a timer circuit, which is the fixing roller 1.
Within a predetermined time after the surface temperature of the
Whether the print signal is input from the / F circuit 15 is C
This is a circuit for the PU 13 to make a determination, and the predetermined time is
As shown in part A of FIG. 5, it is a time required for the surface temperature difference between the fixing roller and the pressure roller to be a temperature difference satisfying a sufficient fixing condition, and is preset as a timer time.

Reference numerals 18 and 19 denote paper feed cassettes A and B,
The CPU 13 determines whether the recording material is plain paper or OHT.

The fixing temperature control method of the present invention will be described below with reference to FIGS. First, after the power is turned on, the CPU 13 checks the fixing roller surface temperature data input from the A / D converter 12 and performs an initial check such as a thermistor disconnection check (S ₁ ). Then, whether the paper feed cassette is plain paper or OHT. After confirming (S ₂ , S ₃ , S ₄ ), the rotation speed data corresponding to the paper type is set in the built-in RAM.

If the fixing surface temperature is lower than the fixing standby temperature in S ₅ , the SSR 16 is driven so that the heater 3 is fully turned on, and the DC motor 9 is operated at the rated speed (25
The DC motor drive circuit 14 is driven so as to rotate at 0 rpm). When the fixing roller surface temperature becomes fixing standby temperature at S _7, CPU 13 sends a start signal to the timer circuit 20 (S _8).

If the print signal is not input from the I / F circuit 15 within the predetermined time (S ₉ ), the CPU 13 judges that the temperature deviation between the fixing roller 1 and the pressure roller 2 has decreased, and changes the motor speed. reads the type of the recording material stored in the RAM to, is varied in order to process speed corresponding to the sheet type (S _10, S _11).

Next, as shown in FIG. 3, when there is a printer signal within a predetermined time, the motor speed is kept constant, and when the surface temperature of the fixing roller reaches the fixing target temperature (S ₁₅ ), the fixing speed is set. Is changed according to S ₁₁ (S ₁₆ ).

It should be noted that the time from the fixing standby temperature to the fixing target temperature is such that the recording material is fed and the electrophotographic process processing such as latent image development, transfer, etc. is carried out. Is set or heater heating control is performed.

[0077] The surface temperature difference [Delta] T 'is fixed between the fixing roller 1 and the pressure roller 2 immediately after the recording material has passed between rollers as in the predetermined fixing S ₁₇ is performed in S ₁₇ FIG. 5B section Since it becomes larger than the temperature difference ΔT before the start, in order to correct this, the decrease rate of the fixing roller surface temperature is measured when the fixing operation starts (S ₁₈ ), and the RA inside the CPU 13 is measured.
Store in M.

If the print signal is not continuously input (S ₁₉ ), the heating of the heater 3 is stopped (S ₂₀ ), and the RAM is read again.
The fixing roller surface temperature decrease rate data stored in is read out and the rotation speed of the DC motor 9 is varied by referring to the table stored in the CPU 13 as shown in FIG. 4 (S ₂₁ ).

When the surface temperature of the fixing roller reaches the fixing standby temperature, the process waits until the next printing starts, or the end command is issued to end the process (S ₁₂ , S ₁₃ ).

Explaining the second embodiment, in the first embodiment, the rotation speed of the roller is switched every time a print signal from the I / F circuit is input. However, when a process such as continuous printing is performed, the CPU determines that the input from the I / F circuit includes information on the number of continuous sheets, and determines the surface temperature of the fixing roller after the fixing process for the first sheet. The lowering rate is stored, and thereafter, the heat distribution of the fixing roller and the pressure roller is maintained by increasing the roller rotation speed until the number of sheets is finished with reference to the lowering rate. 6, 7 (a) and (b) show the operation flow.

The third to fifth inventions according to claims 4 to 10
The embodiment of FIG. 8 will be described with reference to FIGS.

FIG. 8 is a schematic diagram when the present invention is implemented in a printer. A fixing roller 101 includes a heater (hereinafter, abbreviated as a fixing heater) for heating the fixing roller inside. A fixing roller 102 is a fixing roller 1.
01 and the pressure roller 102 are rotated to pass the sheet 103 on which the unfixed toner is placed, thereby causing the toner
Fix to 3. A holder 104 holds a movable temperature sensor. Reference numeral 105 denotes a sensor that detects the paper that has passed through the fixing roller, and the detection signal is the paper detection signal P.
As DP (hereinafter abbreviated as PDP signal), a microcomputer or a central control unit 201 for controlling the printer
(Hereinafter abbreviated as CPU 201).

Reference numeral 106 denotes a temperature sensor, which is used as the fixing roller 1.
The surface temperature of 01 is detected. 108 is the temperature sensor 10
6 is a solenoid for moving the temperature sensor 106, which operates when a drive signal THRSLD (hereinafter abbreviated as THRSLD signal) output from the CPU 201 is turned on.
Is pressed against the fixing roller 101. 107 is an arm that transmits the driving force of the solenoid 108. 109 is TH
A spring for returning the movable part of the solenoid to its original position when the RSLD signal is turned off.

Reference numeral 111 is a gear for transmitting the driving force from the motor to the electromagnetic clutch 112, and 113 and 114 are gears for transmitting the rotational force of the fixing roller 101 to the pressure roller 102. The electromagnetic clutch 112 is an electromagnetic clutch drive signal THRCLD (hereinafter, TH
Controlled by the RCLD signal)
When the signal is on, the clutch is connected and the driving force from the motor is transmitted to the fixing roller 101.

FIG. 9 is a block diagram showing the electric circuit configuration of the embodiment. A controller 202 communicates with the printer and sends a print command to the printer by a signal. Reference numeral 203 denotes a motor drive circuit for conveying the paper, which is CP
Motor drive signal MON output from U201 (hereinafter,
The motor M is driven by the MON signal. 20
Reference numeral 4 is a drive circuit for the electromagnetic clutch 112, and 205 is a drive circuit for the solenoid 108. Reference numeral 208 denotes a drive circuit for the heater 209 incorporated in the fixing roller 101, and C
A triac is driven by a heater drive signal FSRD (hereinafter abbreviated as FSRD signal) output from the PU 201, and AC power is supplied to the heater 209 to heat it. 207
Is an input circuit of the temperature sensor 106, and a detection signal THR
S (hereinafter abbreviated as THRS signal) is input to the analog-digital conversion port of the CPU 201.

FIG. 10 is a diagram showing the timing of each drive signal in the embodiment. When the controller 202 outputs a PRNT signal which is a print command to the CPU 201, C
The PU 201 turns on the MON signal, and the paper transport motor M
To drive. Further, the CPU 201 operates a sheet feeding drive device (not shown) to convey the sheet into the printer, and when image preparation is completed, image formation is performed in synchronization with a synchronization signal VSYNC (hereinafter, abbreviated as VSYNC signal) output from the controller 202. To start. Until then, THR
The CLD signal is off, and the fixing roller 101 remains stopped. Further, the THRSLD signal remains on, the temperature sensor 106 is in contact with the fixing roller 101, and the surface temperature of the fixing roller 101 is detected.

C after a time T ₀ from the leading edge of the VSYNC signal
PU201 stops temperature detection, T further time T after ₃
Turn off the HRSLD signal and set the temperature sensor to the fixing roller 1.
No contact with 01. Furthermore, after time T ₂ , THRCL
When the D signal is turned on, the fixing roller 101 and the pressure roller 10
Rotate 2. The paper sensor 10 installed immediately downstream of the fixing roller 101 after time T ₅ from the VSYNC signal.
The leading edge of the sheet is detected when the PDP signal of 5 becomes high level.

This time T ₅ is at least THRCLD
After the signal is turned on, and the THRCLD signal requires a transport time T ₁ or more from the fixing roller 101 to the sheet sensor 105. When the PDP signal of the paper sensor goes low, the rear edge of the paper is detected and at the same time T
The HRCLD signal is turned off, the electromagnetic clutch is disengaged, and the fixing roller 101 and the pressure roller 102 are stopped from rotating.
Further, after time T ₂ , THRSLD is turned on to bring the temperature sensor 106 into contact with the fixing roller 101. Then, the temperature detection is restarted after T ₄ seconds. This time T ₄ is
The time is sufficient to saturate the heat capacity of the temperature detection mechanism.

The temperature detection is performed only when the temperature sensor 106 is in contact with the fixing roller 101, and the fixing heater 209 is also driven only when the temperature sensor 106 detects the temperature. Therefore, as shown in FIG. 10, the surface temperature of the fixing roller 101 only decreases while the fixing roller 101 rotates to convey the sheet. The control temperature while the rotation of the fixing roller is stopped is set higher so that the absolute lower limit of the fixing temperature is not reached even if the fixing roller 101 rotates in consideration of the surface temperature drop.

FIG. 11 is a flow chart showing a part of the program of the CPU 201 which controls the time chart shown in FIG. The PRNT signal is determined in 101S, and if the print command is received, the control temperature of the fixing roller surface is set to the temperature T in 102S. VSY for 103S
If the NC signal is detected and the VSYNC signal is input, the timer for sheet conveyance is started at 104S. In 105S, it is determined that this timer has elapsed time t ₀ , and in 106S, the temperature detection on the surface of the fixing roller is stopped. In 107S, the timer is further time t ₃
If it has, then 108
At S, the THRSLD signal is turned off. Similarly, 109
In S and 110S, the THRCLD signal is turned on if the timer has further passed the time T ₂ .

If the timer has passed the time t ₅ + α in 111S, it is confirmed in 112S that the PDP signal is on. If the PDP signal remains off, 1
Paper jam processing is performed at 13S. Time α is a jam detection margin. In 114S and 115S, the THRCLD signal is turned off after waiting the elapse of time t ₆ , which is the transport time of the sheet passing over the temperature sensor 106. 1 more
At 16S, wait for the passage of time α and confirm that the PDP signal is turned off. If it remains on, the paper jam processing of 113S is performed. Then, at 118S and 119S, the temperature detection is restarted after waiting the time t ₅ + t ₆ + t ₄ of the timer.

The time chart of FIG. 12 shows the fourth embodiment of the present invention. In the third embodiment, when the fixing roller 101 is rotating and the temperature sensor is not in contact, the temperature control of the surface of the fixing roller is not performed. In the second embodiment, the temperature control is performed even when the temperature sensor is in the non-contact state. CPU2 until the THRSLD signal is turned off in synchronization with the VSYNC signal from the controller
The control of 01 is the same as that of the first embodiment. After this, C
The PU 201 changes the control temperature to control the surface temperature of the fixing roller. The control temperature when the temperature sensor 106 is separated from the fixing roller 101 is set to be lower than the control temperature when the temperature sensor 106 is in contact.

This is because when the temperature sensor is not in contact, the heat capacity is large, and the temperature of the surface of the fixing roller becomes higher than the temperature detected by the temperature sensor, and this is corrected.
This correction temperature increases as the temperature sensor is moved away from the fixing roller. By this control, the same effect as in the third embodiment can be obtained, and even if the temperature sensor 106 is not in contact with the fixing roller, the temperature of the surface of the fixing roller is controlled, so that a special environment, for example, Even if the voltage of the AC power supply supplied to the fixing heater is near the lower limit of the rating, the toner can be fixed on the paper.

The time chart of FIG. 13 shows the fifth embodiment of the present invention. In the third embodiment, when the fixing roller 101 is rotating and the temperature sensor is not in contact, the temperature control of the surface of the fixing roller is not performed. In the fifth embodiment, immediately after the temperature sensor is brought into the non-contact state, a fixed time t
Only for _{7, the} FSRD signal was turned on and the fixing roller 101 was heated. This time t ₇ is a time in which the fixing heater 209 supplies the amount of heat necessary to keep the temperature of the fixing roller surface deprived by the rotation of the fixing roller 101 and the pressure roller 102 and the sheet conveyance constant. This control not only achieves the same effect as in the first embodiment, but also controls the control temperature when the temperature sensor is in contact with the fixing roller.
It can be set near the lower limit of the fixing temperature.

Next, sixth to eighth embodiments according to claims 11 and 12 will be described with reference to FIGS. 14 to 22 (excluding FIGS. 16 and 17).

14 and 15 show a sixth embodiment of the present invention.

The structure, function, and mutual relationship of each member are substantially the same as those in FIGS.

However, two thermistors, a movable thermistor 307 for detecting temperature with respect to the heating roller 301, which comes into contact with the heating roller 301, and a non-contact type thermistor 306 installed with the heating roller 301 in a certain space are provided. is there.

Before the printing operation, during the warming up of the fixing device (the operation of raising the fixing device temperature to the set temperature during standby), the heating roller 301 is not rotated and the heater 30 is used.
Turn on 2 to heat the fuser to the standby temperature.

At this time, the movable contact type thermistor 307
In response to a command from the microcomputer 310, is pressed against the heating roller 301 by a mechanical component such as a solenoid in the thermistor movement control means 308, and the movable contact type thermistor 307 and the non-contact type thermistor 306 are connected.
The temperature will be measured with two thermistors. Since the thermistor 307 is in contact with the heating roller 301, the surface temperature of the heating roller 301 can be accurately measured. However, since the thermistor 306 is not in contact with the heating roller 301, the thermistor 306 has a space with the heating roller 301. Indicates a low temperature.

However, when the spatial distance between the thermistor and the object to be measured is several millimeters or less, the temperature measured by the thermistor decreases in proportion to the distance. Therefore, when the non-contact thermistor 306 and the heating roller 301 are fixed in a fixed space in a certain space, the temperature measured when the movable contact-type thermistor 307 is in contact with the heating roller 301 and the non-contact The temperature difference measured by the die thermistor 306 is a temperature determined by the spatial distance between the non-contact thermistor 306 and the heating roller 301.

In other words, if the above temperature difference is used as a correction value and is added to the measurement value of the non-contact type thermistor 306, the same value as that of the movable contact type thermistor 307 which is in contact with the heating roller 301 to measure the surface temperature. Becomes

As described above, the correction value, which is the difference between both thermistors, is a constant because it is a numerical value determined by the distance between the non-contact thermistor 306 and the heating roller 301. Therefore, it suffices to perform the measurement once and make the setting.

Therefore, the temperatures of the two thermistors are measured, the difference is obtained by the microcomputer 310, the difference is stored in a register in the computer as a correction value, and the thermistor movement command is sent from the microcomputer 310 to the thermistor movement control means 8 to make the thermistor move. 307 is the heating roller 3
It is fixed at a position away from 01.

After that, the measurement is performed only by the non-contact thermistor 306, the correction value in the register is added to the measured value of the non-contact thermistor 306 in the microcomputer 310 to obtain the surface temperature of the heating roller 301, and the comparison with the set temperature is performed. The temperature is maintained at a constant temperature by sending a blinking signal of the heater to the heater control circuit 311 and controlling the on / off of the heater by the heater control circuit 311.

The above series of microcomputers 310
FIG. 20 shows a flowchart of the above. Power on (301
Then, the heater 302 is turned on with the heating roller 301 stopped (302S). The movable contact type thermistor 307 is brought into contact with the heating roller 301 (30
3S). Wait until the temperature detected by the movable contact thermistor 307 reaches the standby temperature (304S).

When the temperature detected by the movable contact thermistor 307 reaches the standby temperature, the difference between the temperature detected by the movable contact thermistor 307 and the temperature detected by the non-contact thermistor 306 is calculated and stored as a correction value (305S). ). The movable contact type thermistor 307 is separated from the heating roller 301 (306S). The control for stopping the heating roller 301 is released, and thereafter, the heating roller 301 is controlled by a print signal or the like.
Can be rotated (307S).

The detected temperature of the non-contact type thermistor 306 and the correction value of (305S) are added, and the value is added to the heater 302.
As the temperature of, the set temperature is monitored (308S).
When the temperature of the heater 302 is lower than the set temperature, the heater 302 is turned on (309S), and when the temperature of the heater 302 is higher than the set temperature, the heater 302 is turned off (310
S), the temperature of the heater 302 is controlled.

18 and 19 show a seventh embodiment. The structural function and the mutual relation of each member are substantially the same as those in FIGS. However, the movable contact type thermistor and the thermistor movable control can be mounted and removed as a jig from the outside of the main body of the image forming apparatus in a cassette type, and when mounted, an adjustment cassette type for contacting the heating roller 301 to measure the temperature. The contact type thermistor 309 is changed to a memory 312 for data storage.

Heating roller 3 of non-contact type thermistor 306
The temperature difference between the surface temperature of the heating roller 301 and the measured temperature of the thermistor 306 due to the spatial distance from 01 is performed in the same manner as described in the above embodiment, but not the movable contact type thermistor, but the image forming apparatus. In the adjustment process in the assembly of the above, the cassette-type thermistor 309 is used as an adjustment jig from the outside of the main body of the image forming apparatus.
1 is attached so as to come into contact with the non-contact thermistor 3
06 and the temperature of the cassette type contact type thermistor 309 for adjustment, and the stem is obtained by the microcomputer 310.
This stem is stored in the memory 312 as a correction value. A non-volatile memory or the like is used as the memory 312 so that the correction value, which is data, is not erased even when the power is off.

When the above correction values are stored in the memory,
After the temperature adjustment process of the non-contact thermistor of the image forming apparatus is completed, the adjustment cassette type contact thermistor 309 is removed from the image forming apparatus.

FIG. 21 shows a flowchart of the microcomputer 310 in the above adjustment process.

To start the adjustment process (311S), first, the adjustment cassette type contact thermistor 309 is attached to the image forming apparatus (312S).

After that, when the power source is turned on (313S), the heater 302 is turned on while the heating roller 301 is stopped (314S). Adjustment cassette type contact thermistor 3
Wait until the detected temperature of 09 becomes the standby temperature (31
5S). When the detection temperature of the adjustment cassette type contact thermistor 309 reaches the standby temperature, the difference between the detection temperature of the adjustment cassette type contact thermistor 309 and the detection temperature of the non-contact type thermistor 306 is taken as the correction value (316).
S).

The correction value is stored in the memory 312 (317).
S). After saving the correction values, turn off the power (318S) and remove the cassette-type contact thermistor for adjustment (31
9S), the adjustment process ends (320S).

After the adjustment step, the temperature is measured only by the non-contact thermistor 306, the correction value in the memory is added to the measured value of the non-contact thermistor 306 in the microcomputer 310, and the surface temperature of the heating roller 301 is obtained and set. The temperature is kept constant by comparing the temperature and sending a blinking signal of the heater to the heater control circuit 311 so that the heater control circuit 311 controls ON / OFF of the heater.

FIG. 22 shows a flowchart of the microcomputer 310 in the normal process after the above adjustment.
When the power is turned on (321S), the heater 302 is turned on (322S). The value obtained by adding the correction value stored in the memory to the temperature detected by the non-contact type thermistor 306 is set as the temperature of the heater 302, and the temperature of the heater 302 is waited until it reaches the standby temperature (323S).

After the heater 302 reaches the standby temperature, the temperature of the heater 302 is monitored for the set temperature (324S). When the temperature of the heater 302 is lower than the set temperature, the heater 302 is turned on (325S), and the heater 3
When the temperature of 02 is higher than the set temperature, the heater 302 is turned on.
FF is performed (326S), and the temperature of the heater 302 is controlled.

In the above-mentioned embodiment, the thermistor is used as the temperature detecting element. The thermistor can be easily used as a temperature sensor, and the change width of resistance with respect to temperature can be wide, but it also has the drawback of being non-linear with respect to temperature.

Therefore, in the eighth embodiment, a thin film resistance temperature sensor can be used instead of the thermistor.
This makes the programming of the CPU easy because it is linear with temperature.

23 to 29, the ninth to eleventh embodiments of the invention according to claims 13 to 15 will be described.

23 to 24 show a ninth embodiment of the present invention, and FIG. 23 is a sequence chart of power supplies, signals, etc., including a host computer power supply, printer fixing heater energization control signal, printer power supply, and print signal. ON, O
This shows the relationship of FF timing.

In FIG. 24, 401 is a printer and 40
Reference numeral 2 is a host computer, and 403 is a power supply synchronizing circuit for synchronizing a power ON signal of the host computer 403 and a fixing heater energization control signal of the printer 401.

Next, in the above configuration, the synchronizing circuit 4 is synchronized with turning on the power of the host computer 402.
From 03, the power supply of the heater for starting the energization control of the fixing heater of the printer 401, the power supply of the control circuit, etc. are turned on.
At this time, the power supplies for the scanner motor and main motor of the printer and the power supplies for the control circuits for these motors may be turned off. When the printer power source is turned on before the host computer power source, control of the printer fixing heater energization control signal is naturally started in synchronization with this.

As a result, even if the power of the printer is turned off, the energization control of the fixing heater is started, and the surface of the fixing roller is sufficiently heated before the power of the printer is turned on and the print signal is turned on. Therefore, as can be seen from FIG. 25 (B), since the temperature difference from the print control temperature is only about 80 ° C., a diagram showing the conventional overshoot (FIG. 25 (A)).
Compared with, overshoot can be kept low.

As a result, the reduction in the amount of reverse crown due to the thermal expansion of the surface of the fixing roller is reduced, and the effect of preventing the occurrence of "paper wrinkles" in the central portion of the image such as the solid black image on the few sheets after the start of printing is provided. You can

The energization control signal for the printer fixing heater is turned off in synchronization with the power-off of the printer.
Set to F.

FIGS. 26 to 27 show a tenth embodiment of the present invention. FIG. 26 is a sequence chart of a power supply, signals, etc., and a host computer power supply, software RUN for word processor software, spreadsheet, graph display, etc. Signals, printer fixing heater temperature control signal, power supply for printer, ON / OFF timing of print signal, etc. are shown.

In FIG. 27, 401 is a printer and 40
Reference numeral 2 is a host computer, and reference numeral 404 is a synchronizing circuit in the DC controller for synchronizing with a fixing heater energization control signal of the printer 401 in synchronization with the software RUN signal of the host computer built in the printer 401.

Next, in the above-mentioned configuration, in synchronization with turning on the software RUN signal for word processing software, spreadsheet, graph display, etc., the fixing heater energization control of the printer 401 is performed from the synchronizing circuit 404 built in the printer 401. The power supply of the heater, the power supply of the control circuit, etc. for starting At this time, the power of the scanner motor and main motor of the printer and the power of the control circuit of these motors are turned off.
It may be FF.

As a result, the same effect as that of the ninth embodiment can be obtained. In the tenth embodiment, since the RUN signal of word processor software or the like is used as the synchronization signal, only the control circuit in the printer 401 needs to be controlled, and the hardware such as the power supply synchronization circuit of the ninth embodiment is unnecessary, resulting in cost reduction. It also has the advantage of being advantageous.

Also in this embodiment, the energization control signal for the printer fixing heater is turned off in synchronization with the power off of the printer.

28 to 29 show an eleventh embodiment of the present invention, and FIG. 28 is a sequence chart of power supplies, signals, etc., including a host computer power supply, printer fixing heater energization control signal, printer power supply, print signal. , And the ON / OFF timing of the residual heat SW.

In FIG. 29, 401 is a printer and 40
Reference numeral 2 is a host computer, and 405 is a residual heat control unit including a residual heat switch SW (manual) for switching the power supply to the fixing heater built in the printer 401 to a residual heat state, a residual heat control circuit, and the like. Next, in the above configuration,
The printer 401 and the host computer 402 are powered off.
Even in the case of FF, when the residual heat switch SW (manual) is turned on, the printer fixing heater energization control signal is also turned on in synchronization with this. As a result, the power supply of the heater for starting the energization control of the fixing heater of the printer 401, the power supply of the control circuit, etc. are turned on.

At this time, the power supplies of the scanner motor and the main motor of the printer and the power supplies of the control circuits of these motors may be turned off.

With this structure, the same effect as that of the ninth embodiment can be obtained.

In this embodiment, since the residual heat switch SW can be manually turned on and off, it can be turned on when the user of the printer decides to leave the printer and the transfer material in a high temperature and high humidity environment. It also has the effect of energy saving that the energization of can be suppressed to the necessary minimum.

The energization control signal for the printer fixing heater is turned off in synchronization with turning off the residual heat switch SW.

Next, the twelfth to fourteenth embodiments according to the billing schools 16 to 18 will be described with reference to FIG.

A twelfth embodiment of the present invention will be described with reference to FIG. Reference numeral 501 is a printer engine, 502 is a printer controller, 503 is a mechanism control unit, and 504 is a fixing device. When the printer engine 501 is powered on and the initialization process is completed, the PPRDY signal 513 is set to true.

The temperature signal 506 output from the thermal sensor such as the thermistor of the fixing device 504 causes the fixing device 504 to operate.
The fixing device 504 is maintained at a predetermined temperature by turning on and off the driving current 505 to the fixing device 504.

The printer engine 501 confirms that the temperature of the fixing device 504 has reached the specified temperature and that there is paper in the paper feed port designated by the paper detection mechanism 507 and the paper cassette detection mechanism 508, and the toner cartridge detection mechanism 509. , When the door open detection mechanism 510, the jam detection mechanism 511, the failure detection mechanism 512, etc. are not in the print-disabled state, and when the CPRDY signal is true, the RDY signal 515 is set to true and the PRINT signal 517 is received. The printing operation becomes possible.

When the RDY signal 515 is true, the door open detection mechanism 510 confirms that the door is open, the jam detection mechanism 511 detects a jam, and the failure detection mechanism 512 repairs the jam. RDY signal 515 when a failure that requires
Is set to false, and the driving current for the fixing device 504 is 50
Stop 5.

In the case of door opening or jamming, after confirming that the door is closed by the door opening detection mechanism 510, the fixing device 504 is controlled to the specified temperature.

Conditions other than those described above in which the RDY signal is false, no paper, no paper cassette, no toner cartridge are detected by the paper detection mechanism 507 and the paper cassette detection mechanism 5.
08, the toner cartridge detection mechanism 509 detects the RDY signal 515 at a predetermined address of the RAM whose value is set to 0 when the mechanism control unit 503 is initialized by the program in the ROM of the mechanism control unit 503.
While the status is false, the value is incremented by 1 each time a timer interrupt is generated and compared with the value set at a predetermined address in the ROM. If they are equal, the drive current 505 to the fixing device 504 is stopped.

When the condition for the three RDY signals 515 to become FALSE is released, the drive current 505 for the fixing device 504 is supplied, and the temperature signal 506 controls within the specified temperature range.

At this time, when the temperature of the fixing device 504 reaches the specified temperature, the RDY signal 515 is set to true, and the value of the predetermined address of the RAM for recording the value of the above time is set to 0. While the RDY signal 515 is false according to any of the above three conditions, the RDY signal 515 of the above three conditions is false while the time count value on the RAM is smaller than the time value set on the ROM. When the condition that becomes is released, the RDY signal 515 is set to true.
Then, the value of the predetermined address of the RAM for counting the value of the above time is set to 0. In this case, the fixing device is kept within the specified temperature range.

A thirteenth embodiment of the present invention will be described with reference to FIG. When the printer engine 501 is powered on, the PPRDY signal 513 is set to true, and CPRD
The Y signal 514 is true, the temperature signal 506 of the fixing device 504 indicates that the fixing device 504 is within the specified temperature range,
Also, the paper detection mechanism 507, the paper cassette detection mechanism 508, the toner cartridge detection mechanism 509, and the door open detection mechanism 51.
When 0, the jam detection mechanism 511, and the failure detection mechanism 512 confirm that the printing is not disabled, the RDY signal 515 is set to true.

When the RDY signal becomes true, the RDY signal 515 is set to true at a predetermined address of the RAM whose value is set to θ when the mechanism control unit 503 is initialized by the program in the ROM of the mechanism control unit 503. For a while, add 1 each time a timer interrupt occurs and compare with the value set in the specified address in ROM
When they are equal, the drive current 505 to the fixing device 504 is stopped.

When the PRINT signal 517 from the printer controller 502 is received, the drive current 505 to the fixing device 504 is supplied, the temperature signal 506 is detected, and when the specified temperature is reached, the vertical synchronization request signal VSREQ 518 is output and the vertical signal is output. After receiving the synchronization signal VSYNC519, the video signal VDO51 output by the printer controller 502 in synchronization with the horizontal synchronization signal BD525 after a predetermined time.
6 forms an image.

When the print signal PRINT 517 is received before the predetermined time is counted in the above state,
The set value of the RAM time is set to θ.

Also, when the RDY signal 515 is set to false, the set time value of the RAM is set to 0. In addition, the RDY signal 515 is true and the PRINT signal 5 is added when the value of the RAM is added every time an interrupt is generated by the timer interrupt process.
Perform when 17 is false.

A fourteenth embodiment of the present invention will be described with reference to FIG.

For the twelfth and thirteenth embodiments, the printer controller 502 sets the CBSY signal 523 to t.
By setting to true, synchronizing with the CLK signal 522, and sending a predetermined command, the mechanism control unit 503 is instructed to turn on or off the function.

Next, the fifteenth to eighteenth embodiments of the nineteenth aspect will be described with reference to FIGS.

FIG. 32 shows a fifteenth embodiment of the present invention.

In FIG. 32, a thermistor 620 which is a temperature sensitive element as a temperature detecting means is held in contact with the fixing roller 601 at a distance l ₁ . Here, the thermistor 620 is mounted on a heat insulating substrate 622, and this substrate 622 is fixed by a spring 623 to the fixing roller 601.
It is fixed to a heat-resistant holder 621 made of polyimide resin or the like, which is a supporting member for holding the gap between and.
625 is a lead wire of the thermistor 620.

At this time, the closest distance between the holder 621 and the fixing roller 601 in the vicinity of the thermistor 620 is 1
_Set to ₂ . The opening m of the holder 621 was 15 mm.

Under these conditions, when l ₂ > l ₁ , the air layer in the space near the thermistor 620 easily escapes due to convection due to heat or rotation of the fixing roller 601. , The temperature is lowered by being cooled by the outside air.

As a result, the difference Δ between the surface temperature T _r of the fixing roller 601 and the temperature T _s detected by the thermistor 620 described above.
T = T _r −T _s increases.

On the other hand, if l ₂ ≤l ₁ , the thermistor 6
The air layer near 20 accumulates and the temperature of the thermistor 620 rises with the temperature of the fixing roller 601, so that the increase of ΔT can be prevented and the responsiveness is improved.

As an example, l ₁ = 0.8 mm, l ₂ =
It was a 0.5 mm, improved responsiveness to T _s' from T _s in FIG. 33.

Note that, in FIG. 32, a holder 621.
Although the gap is set to l _{2 in} both the upstream and the downstream when viewed from the rotation direction of the fixing roller 601, it is effective to set only one of the gaps to be smaller than l ₁ .

If l ₃ <l ₄ <l ₂ or l ₃ <l ₂ <l ₄ where l _{3 is} the upstream gap and l ₄ is the downstream gap, foreign matter such as toner When the lumps of the like are larger than l ₃ , stop at the upstream holder,
If smaller than l ₃ , holder 621, thermistor 6
Since it passes without touching any of the 20, the thermistor 6
At the same time, the effect of preventing 20 stains can be obtained.

Further, with respect to the axial direction of the fixing roller 601, it is possible to prevent heat from escaping in the axial direction by making the size of the holder 621 sufficiently long, but as shown in FIG. Once covered with 621, it is effective.

The cross-sectional shape of the holder 621 on the surface facing the fixing roller 601 may be either a linear shape as shown in FIG. 32 or an arcuate curved shape as shown in FIG.

The holder 621 is attached to the fixing roller 601.
39 may be used, but the holder 621 may be extended in the axial direction of the fixing roller 601 and brought into direct contact with the outside of the sheet passing area of the fixing roller 601. According to the method, the accuracy of the gaps l ₁ and l ₂ can be improved.

Furthermore, in the fifteenth embodiment,
The fixing roller 601 and the pressure roller 605 were used. Although the pair of roller fixing means (see FIG. 38) has been described, the present invention can be similarly applied to a heat fixing device in which a belt-like heat fixing means and a pressure means are combined. Of course.

FIG. 35 shows a sixteenth embodiment of the present invention.

In FIG. 35, ribs 624 are provided on the facing surface of the fixing roller 601 of the holder 621 in the fifteenth embodiment, whereby the surface area of the holder 621 on the facing surface is increased and the air flow is made more effective. It's suppressed. As a result, the value of the temperature detected by the thermistor 620 can be raised more quickly.

FIG. 36 shows a seventeenth embodiment of the present invention. In FIGS. 36A and 36B, the lead wire 625 of the thermistor is arranged so as to partially pass through the space A formed by the holder 621 and the fixing roller 601 in the fifteenth embodiment.

By arranging in this manner, the lead wire 625 is heated in the space A, so that it is possible to prevent heat from escaping from the thermistor 620 to the outside through the lead wire 625.
The responsiveness of temperature detection by the thermistor 620 can be improved.

FIG. 37 shows an eighteenth embodiment in which the present invention is applied to a thermoswitch 626 for preventing runaway of a fixing device, and l ₂ ≤l ₁ is set. By applying the present invention to the thermoswitch 626 as described above, even when the fixing roller 601 is heated from the cooling state and becomes an abnormal temperature as it is, the temperature of the space B is also rapidly increased and the bimetal 627 is spread over a wide range. It is heated to enable reliable operation.

That is, in FIG. 37, the bimetal 6
27 is bent back in the direction of the arrow, the spacer 630 is pushed up, and the contact between the electrodes 628 and 629 is broken.

As an experimental example, l ₁ = 0.8 mm, l ₂ =
A runaway test (that is, a test of keeping the heating means of the fixing roller 601 in an ON state) was performed using a thermoswitch having a rating of 210 ° C. with a 0.5 mm rating. When the surface temperature of the roller 601 is 300 ° C., the thermoswitch 626 is operated, while the fixing roller 601 is subjected to the runaway test during the printing operation while the temperature is adjusted to 180 ° C.
The thermoswitch operated at 270 ° C.

As a result, it has been found that there is no concern about disconnection due to malfunction of the thermoswitch 626 or ignition due to malfunction.

On the other hand, as in the conventional case, a similar experiment was conducted with l ₁ = 0.8 mm and l ₂ = 2.5 mm so that l ₁ >> l ₂ was obtained. However, the surface temperature of the fixing roller 601 rises to 370 ° C. and smoke is emitted from the fixing device.

In the conventional example, when the rated temperature of the thermoswitch 626 was lowered in order to prevent the smoke emission, an erroneous disconnection occurred during the normal printing operation.

Next, the nineteenth to twenty-second embodiments of the twentieth aspect will be described with reference to FIGS.

FIG. 41 shows a nineteenth embodiment of the present invention.

In FIG. 41, the thermistor 720, which is a temperature sensitive element, is separated from the fixing roller 701 by a distance 1 = 0.5 mm.
It is held in a non-contact state. Where the thermistor 720
Is mounted on a heat-insulating substrate 722, and this substrate 722 is fixed by a spring 723 to a heat-resistant holder 721 such as a polyimide resin which is a supporting member for holding a gap with the fixing roller 701. ing. 725 is a lead wire of the thermistor 720. The opening m of the holder 721 was set to 15 mm.

Under such conditions, a sheet material 724 made of a flexible material as a heat-resistant sealing material is provided on the wall surfaces of the holder 721 on the upstream side and the downstream side as viewed from the rotation direction of the fixing roller 701. 724 is the fixing roller 7
01 is provided so as to abut.

As a result, the air layer in the space near the thermistor 720 is shielded from the surroundings and does not escape to the external space due to convection due to heat or rotation, so that the surface temperature T of the fixing roller 701 when the power is turned on. Even when the change in _r is drastic, as shown in FIG. 42, the temperature T _p detected by the thermistor 720 follows well. In FIG. 42, T _s is the sensor temperature without the sheet material, and T _r is the temperature of the fixing roller 701.

Here, as the material of the sheet material 724,
For example, a material such as fluororesin, polyimide, silicon resin, urethane resin can be used, and in particular, the fluororesin is excellent in heat resistance and low friction, and thus the fixing roller 701 is used.
It is preferable because it is not easily scratched.

The upstream sheet material 724 also has an effect of preventing foreign matter such as a lump of toner from adhering to the thermistor 720.

Further, in FIG. 41, the upstream sheet is in contact with the counter against the rotation of the fixing roller 701, and the downstream sheet is in contact with the forward direction. However, the upstream sheet is in the forward direction or the downstream sheet. Of course, the counter may be brought into contact with the counter.

The holder 721 is attached to the fixing roller 701.
48 may be supported by the above-mentioned method, but the holder 721 may be extended in the axial direction of the fixing roller 701 and directly contacted with the outside of the sheet passing area of the fixing roller 701. According to the method, the accuracy of the gap 1 can be improved.

Furthermore, in the nineteenth embodiment, the pair of roller fixing means (see FIG. 47) using the fixing roller 701 and the pressure roller 705 has been described. It is needless to say that the present invention can also be implemented in a heat fixing device in which a heat fixing unit and a pressure unit are combined.

FIG. 43 shows a twentieth embodiment of the present invention.

In FIG. 43, a felt material 726 is provided as a sealing material on the upper and downstream end surfaces of the holder 721, and the felt material 726 is brought into contact with the fixing roller 701.

The felt material 726 has a density of 0.05.
g / cm ³ by using of about to 0.5 g / cm ^3, at the same time as warmth, good cleaning property is obtained,
It is possible to completely prevent the thermistor 720 from becoming dirty.

Moreover, since the felt 726 can be deformed by the pressure, as shown in FIG.
It is most suitable not only for the rotation direction 726a, 726b of 1 but also for preventing the escape of heat in the axial direction (726c, 72).
6d). Of course, a sheet material 724 may be provided instead of 726a and 726b, and the felt 726c and 726d may be used together.

FIG. 45 shows a twenty-first embodiment of the present invention.

In Examples 19 and 20, as means for keeping the distance 1 between the thermistor 720 and the fixing roller 701,
As shown in FIG. 48, a method of fixing the side plate 716 as a reference, or extending the holder 721 to the outside of the sheet area and directly contacting the fixing roller 701 was used.
Like the felt 72 provided at the opening of the holder 721.
6 may be directly contacted with the fixing roller 720 by using a spring 728.

In this way, the adjustment for positioning the distance 1 is unnecessary, and since only the felt 726 abuts on the fixing roller 720, there is no fear of roller scratches. Incidentally, reference numeral 727 in the drawing is a guide for vertically restricting the movement of the holder 721.

As an example, the guide 721 by the spring 728 is used.
When the pressing force of 100 is set to 100 g / cm ² , the airtightness of the surrounding space of the thermistor 720 is kept good and the distance l
Could be kept stable.

If the pressing force is too low, the hermeticity becomes insufficient, and the thermistor 720 tends to float from the fixing roller 701. On the contrary, if the pressing force is too strong, the felt 726 is compressed due to the durability, and the distance 1 becomes smaller. There is a risk of becoming smaller. Therefore, the pressing force is 10g / cm ² to 1kg.
The range of / cm ² is desirable.

FIG. 46 shows a twenty-second embodiment in which the present invention is applied to a thermoswitch 729 for preventing runaway of a fixing device. The thermoswitch 729 can also have the same configuration as that used in the nineteenth to twenty-first embodiments. Here, the case where the same configuration as that of the twentieth embodiment is used is shown.

When the present invention is applied to the thermo switch 729, the fixing roller 701 is heated from the cooling state, and even if the fixing roller 701 becomes an abnormal temperature as it is, the temperature of the space A is rapidly increased, and the bimetal 727 is spread over a wide range. When heated, it can operate reliably. (That is, in FIG. 46, the bimetal 730 bends back in the direction of the arrow, the spacer 733 is pushed up, and the contact between the electrodes 731 and 732 is broken.) As an example, l = 0.8 mm and the rating 210
When a runaway test (that is, a test of keeping the heating means of the fixing roller 701 in an ON state) was performed using a thermo switch of ℃, the surface temperature of the fixing roller 701 was 290 ° C. in the runaway test when the power was turned on. Then, the thermoswitch 729 operated, and on the other hand, when the runaway test was conducted during the printing operation while the temperature of the fixing roller 701 was adjusted to 180 ° C., the thermoswitch operated at 260 ° C.

As a result, it was found that there is no fear of wire breakage due to malfunction of the thermoswitch 729 or ignition due to malfunction.

On the other hand, when the felt 726 was removed and the same experiment was conducted, the surface temperature of the fixing roller 701 increased to 370 ° C. in the runaway test after the power was turned on, and the disadvantage that smoke was emitted from the fixing device occurred.

At this time, when the rated temperature of the thermoswitch 729 was lowered in order to prevent smoke generation, an erroneous disconnection occurred during the normal printing operation.

[0203]

As described above, according to the first to third aspects of the present invention, in the fixing device having different heat capacities and heat radiating amounts for the fixing roller and the pressure roller, the surface temperature increase rate and the surface temperature decrease rate are increased. By making the roller speed variable at the same time, it is possible to provide fixing with less unevenness and offset under a constant temperature distribution.

According to the fourth to tenth aspects of the present invention, when the fixing roller rotates and the sheet passes therethrough, the temperature sensor is brought into non-contact with the fixing roller to prevent the surface of the fixing roller from being worn due to the rotation. it can. Therefore, it is possible to prevent the fixing roller from being damaged. Further, at the timing when the paper does not pass, that is, between the paper, the rotation driving of the fixing roller is stopped, and the temperature sensor is brought into contact with the surface temperature of the fixing roller to control the surface temperature of the fixing roller. An image with stable quality can be output.

According to the eleventh and twelfth aspects of the present invention, by providing the movable contact type thermistor and the non-contact type thermistor, the non-contact type thermistor can be used regardless of the mounting position of the non-contact type thermistor. The temperature of the fixing device can be accurately measured. As a result, the service life of the fixing device can be extended or the withstand voltage of electric elements in the fixing device can be improved. Further, by changing the movable contact-type thermistor to the adjustment cassette-type contact-type thermistor, it becomes possible to suppress the cost increase of the contact type and the non-contact type thermistors.

According to the thirteenth to fifteenth inventions, the heater of the fixing device is energized and the surface of the fixing roller is preheated in a standby state before the printer starts the printing operation. And the surface temperature of the fixing roller are small, and the overshoot is small. As a result, it is possible to prevent the occurrence of a "paper wrinkle" in the central portion of the image such as a solid black image up to the first few sheets after printing.

According to the sixteenth to eighteenth aspects of the present invention, by providing means for detecting that the printing operation is not performed for a predetermined time, the ON / OFF control of the fixing device is performed to prevent the printing for a long time. There is an effect that the power consumption of the printer engine can be reduced.

According to the nineteenth aspect of the invention, the fixing roller 6
01 and the temperature sensing means such as the thermistor 620 and the thermo switch 626, the closest distance between the heat sensitive element support member 621 and the fixing roller 601 near the heat sensitive element is made smaller than the closest distance. , It became possible to improve the response of the temperature sensitive element. The present invention is also effective for preventing the temperature sensitive element from becoming dirty.

According to the invention of claim 20, the fixing roller 7
01 and a temperature detecting means such as a thermistor 720 and a thermo switch 729 and the like and a temperature-sensitive element such as a temperature sensor, a sealing material made of a flexible sheet material 724, felt 726 or the like is added to the holder 721 to the fixing roller 701. By bringing them into contact with each other, the space in the vicinity of the temperature sensing element was substantially cut off from the outside, and the responsiveness of the temperature sensing element could be improved. Also,
The present invention is also effective for preventing the temperature sensitive element from becoming dirty.

[Brief description of drawings]

FIG. 1 is a sectional view and a control circuit block diagram of a fixing device according to a first embodiment of the invention.

FIG. 2 is a diagram showing the first half of a flow chart for explaining the inter-roller temperature correction control system of the fixing device of the first embodiment of the present invention.

FIG. 3 is a diagram showing the latter half of the flowchart for explaining the inter-roller temperature correction control method of the fixing device of the first embodiment of the present invention.

FIG. 4 is a table diagram for changing a roller rotation speed with respect to a fixing device surface temperature decrease rate.

FIG. 5 is a surface temperature history diagram of the conventional fixing roller and pressure roller from the power-on to the end of the fixing operation.

FIG. 6 is a diagram showing the first half of a control flowchart of a second embodiment of the present invention.

FIG. 7 is a diagram showing the latter half of the control flowchart of the second embodiment of the present invention.

FIG. 8 is a schematic diagram of a third embodiment of the present invention.

FIG. 9 is a block diagram showing a circuit configuration of the present invention.

FIG. 10 is a time chart of the example of the present invention.

FIG. 11 is a flowchart of a control program of the present invention.

FIG. 12 is a time chart in the fourth embodiment of the present invention.

FIG. 13 is a time chart according to the fifth embodiment of the present invention.

FIG. 14 is a sectional view of a heat roller fixing device showing an embodiment of the present invention.

FIG. 15 is a block circuit diagram of a heat roller fixing device according to the present invention.

FIG. 16 is a sectional view of a conventional heat roller fixing device.

FIG. 17 is a block circuit diagram of a conventional heat roller fixing device.

FIG. 18 is a sectional view of a heat roller fixing device showing another embodiment of the present invention.

FIG. 19 is a block circuit diagram of a heat roller fixing device showing another embodiment of the invention.

FIG. 20 is a flowchart of heating control of the fixing device according to the embodiment of the present invention.

FIG. 21 is a flow chart of heating control in the embodiment of FIG. 18 of the present invention.

FIG. 22 is a flow chart of heating control in the post-adjustment process of the embodiment of the present invention.

FIG. 23 is a sequence chart of power supplies, signals, etc. according to a ninth embodiment of the present invention.

FIG. 24 is a configuration diagram of a ninth embodiment of the present invention.

FIG. 25 is a diagram showing a comparison of overshoot between a conventional example and the present invention.

FIG. 26 is a sequence chart of a power supply, signals, etc. according to a tenth embodiment of the present invention.

FIG. 27 is a configuration diagram of a tenth embodiment of the present invention.

FIG. 28 is a sequence chart of power supplies, signals, etc. according to an eleventh embodiment of the present invention.

FIG. 29 is a configuration diagram of an eleventh embodiment of the present invention.

FIG. 30 is a diagram showing a configuration of a conventional fixing device and a light distribution of a heater.

FIG. 31 is a block diagram for explaining twelfth to fourteenth embodiments of the present invention.

FIG. 32 is a drawing showing a fifteenth embodiment of the present invention.

FIG. 33 is a view for explaining the effect of the fifteenth embodiment of the present invention.

FIG. 34 is another drawing showing the fifteenth embodiment of the present invention.

FIG. 35 is a drawing showing a sixteenth embodiment of the present invention.

FIG. 36 is a drawing showing a seventeenth embodiment of the present invention.

FIG. 37 is a drawing showing an eighteenth embodiment of the present invention.

FIG. 38 is a drawing for explaining a conventional example and its problems.

FIG. 39 is a view for explaining another conventional example and its problems.

FIG. 40 is a view for explaining still another conventional example and its problems.

FIG. 41 is a drawing showing a nineteenth embodiment of the present invention.

FIG. 42 is a view for explaining the effect of the nineteenth embodiment of the present invention.

FIG. 43 is a drawing showing a twentieth embodiment of the present invention.

FIG. 44 is another drawing showing the twentieth embodiment of the present invention.

FIG. 45 is a drawing showing a twenty-first embodiment of the present invention.

FIG. 46 is a drawing showing a twenty-second embodiment of the present invention.

FIG. 47 is a drawing for explaining a conventional example and its problems.

FIG. 48 is a drawing for explaining another conventional example and its problems.

FIG. 49 is a view for explaining still another conventional example and its problems.

[Explanation of symbols]

1 ... Fixing roller 2 ... Pressure roller 3 ... Heater 9 ... Motor 10 ... Thermistor 101 ... Fixing roller 102 ... Pressure roller 105 ... Paper sensor 108 ... Solenoid 112 ... Electromagnetic clutch 201 ... CPU 202 ... Controller 203 ... Motor drive circuit 204 ... electromagnetic clutch drive circuit 205 ... solenoid drive circuit 208 ... fixing heater drive circuit 209 ... fixing heater 301 ... heating roller 302 ... heater 303 ... contact type thermistor 304 ... pressure contact roller 305 ... paper 306 ... non-contact type thermistor 307 ... movable contact Type thermistor 308 ... Thermistor movable control device 309 ... Adjustment cassette type contact thermistor 310 ... Microcomputer 311 ... Heater control circuit 312 ... Memory 403 ... Power supply synchronizing circuit 404 ... DC controller built in printer 401 Soft RUN signal synchronizing circuit in roller 405 ... Remaining heat control unit 501 built in printer 401 ... Printer engine 502 ... Printer controller 503 ... Mechanism control unit 504 ... Fixing device 507 ... Paper detection mechanism 508 ... Paper cassette detection mechanism 509 ... Toner Cartridge detection mechanism 510 ... Door open detection mechanism 511 ... Jam detection mechanism 512 ... Failure detection mechanism 601 ... Fixing roller 602 ... Heater 603 ... Pressure roller 620 ... Thermistor 621 ... Holder 622 ... Thermal insulation substrate 624 ... Rib 625 ... Lead wire 626 ... Thermo switch 701 ... Fixing roller 702 ... Heater 703 ... Pressure roller 720 ... Thermistor 721 ... Holder 722 ... Heat insulation substrate 724 ... Sheet material 726 ... Felt material 727 ... Guide plate 728 ... Spring 729 ... Thermo switch

[Procedure amendment]

[Submission date] January 17, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] Fig. 45

[Correction method] Change

[Correction content]

FIG. 45

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Eihiro Sakaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Tomohiro Hashimoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasuo Ito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Fumihiro Ueno 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. In-house (72) Inventor Eiichiro Toyoshima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kaoru Sato 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72 ) Inventor Tomohiro Nakamori 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Izumi Narita 3-30-2 Shimomaruko, Ota-ku, Tokyo Kya Non-Corporation (72) Inventor Yuzo Kiyono 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tatsuto Tachibana 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Akihisa Kusano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Takeji Gima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72 ) Inventor Toshiyuki Ito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Akihiro Nakamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kimizuka Junichi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tetsuo Saito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Satoshi Tokyo 3-30-2 Shimomaruko, Ota-ku Canon Inc. (72) Inventor Akihiko Takeuchi Ota-ku, Tokyo Maruko 3-chome No. 30 No. 2 Canon within Co., Ltd.

Claims (20)

[Claims] 1. A driving means for driving a fixing roller, a variable speed means for varying the fixing roller driving means, a heating means for heating the roller, a temperature detecting means for detecting the surface temperature of the fixing roller, and the temperature detecting means. The fixing roller has a calculating means for calculating the rising characteristic of the fixing roller surface temperature and a decreasing characteristic due to heat radiation, and a reference means for making a table reference for changing the roller variable speed means by the fixing roller temperature characteristic calculating means. A fixing device characterized in that the roller drive can be changed according to the state of the surface temperature. 2. The fixing device according to claim 1, wherein variable speed control of the roller is performed by calculation of rising characteristics and falling characteristics of the surface temperature of the fixing roller to adjust the temperature, except for the fixing process. 3. A paper type discriminating means for discriminating a paper type to be passed, and the roller variable speed means carries out fixing at a fixing speed according to the paper type during fixing processing.
Fixing device. 4. A recording apparatus having a heat fixing system,
A fixing roller, a means for controlling the rotation and stop of the fixing roller, a means for detecting the paper on the fixing roller, a temperature detecting device for detecting the temperature of the surface of the fixing roller, and the temperature detecting device contacting the fixing roller, Alternatively, when there is no recording paper on the fixing roller, the temperature detecting device is brought into contact with the fixing roller, and at the same time, the control means for stopping the rotation of the fixing roller and the recording on the fixing roller are provided. When there is paper, the fixing device has a control means for rotating the fixing roller at the same time as separating the temperature detecting device from the fixing roller. 5. The fixing device according to claim 4, further comprising control means for detecting the temperature of the surface of the fixing roller only when the temperature detecting device is in contact with the fixing roller. 6. The fixing device according to claim 4, further comprising control means for driving the fixing heater only when the temperature detecting device is in contact with the fixing roller. 7. The fixing device according to claim 4, further comprising control means for delaying the temperature detection start timing by a time corresponding to a thermal time constant of the temperature detection device when the temperature detection device is in a non-contact state. . 8. The control means for setting the control temperature of the fixing roller to the fixing temperature lower limit + the temperature decrease amount due to sheet passing or more when the temperature detecting device is in contact with the fixing roller. 4 fixing device. 9. The control temperature when the temperature detecting device is in a non-contact state has a control that is set to a lower value depending on the heat capacities of the fixing roller and the temperature detecting device than when the temperature detecting device is in a contact state. The fixing device according to claim 4, wherein: 10. The fixing device according to claim 4, further comprising control means for heating the fixing roller for a predetermined time when the temperature detecting device is in a non-contact state, that is, when the sheet passes through the fixing roller. 11. A temperature sensor for a fixing device comprising two movable contact-type thermistors and non-contact-type thermistors,
A fixing device characterized in that the temperature of the fixing device is controlled by the two thermistors. 12. A contact type thermistor is used as a jig in place of the movable contact type thermistor, and adjustment is performed during the assembly process of the image forming apparatus, so that the fixing unit can be fixed with only one non-contact type thermistor. The fixing according to claim 11, wherein temperature control is performed. 13. A fixing device in an electrophotographic printer, wherein energization control to a heater of a fixing device of the printer is started in synchronization with power-on of a computer or a printer on a host side. 14. In an electrophotographic printer, the energization control to the heater of the fixing device of the printer is started in synchronization with a software signal such as the start of word processor software operation of the host computer or the power-on of the printer. Characterizing fixing device. 15. A fixing device in an electrophotographic printer, which has a residual heat function for controlling energization of a heater of a fixing device of the printer even when the power supply of a computer on the host side is turned off. 16. A printer engine having means for fixing toner by heat and means for notifying a printer controller of a printable state, except that the fixing means has not reached a specified temperature. A fixing device characterized in that when the unprintable state continues for a predetermined time or more, the energization of the heater of the fixing means is stopped until the printable state is reached excluding the temperature of the fixing device. 17. A printer engine having means for fixing toner by heat, means for notifying the printer controller of a printable state or not, and means for receiving a print start signal from the printer controller is set to a printable state. When a print start signal is not received even after a lapse of a predetermined time from the time when the temperature is reached, the fixing device stops energizing the heater of the fixing means until the print start signal is received. 18. A fixing device comprising a means for detecting ON / OFF according to claim 16 or 17, and capable of turning ON / OFF the mechanism. 19. A heat fixing unit for fixing an image supporting member having a toner image on its surface through a nip portion thereof,
A pair of pressurizing means and a temperature detecting means arranged to face the heat fixing means in a non-contact state so as to detect the temperature near the surface of the heat fixing means; and a supporting member for supporting the temperature detecting means. And the closest distance between the heat fixing means and the temperature detecting means is l ₁ and the closest distance between the heat fixing means in the vicinity of the temperature detecting means of the supporting member is l ₂ , a fixing device, characterized in that constructed as a l ₂ ≦ l _1. 20. A heat fixing means for fixing an image supporting member having a toner image on its surface through a nip portion thereof.
And a pair of pressurizing means, a temperature detecting means arranged to face the heat fixing means in a non-contact state so as to detect the temperature in the vicinity of the surface of the heat fixing means, and a support for supporting the temperature detecting means. In a thermal fixing device having a member, holding a heat-resistant sealing material in the vicinity of the temperature detecting means of the supporting member,
A fixing device characterized in that the space in the vicinity of the temperature detecting means is substantially cut off from the outside by bringing this into contact with the heat fixing means.