JPS6210430B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fixing temperature control when thermally fixing a toner image on recording paper, and in particular to a recording device that directly forms a latent image on electrostatic recording paper and develops it, and a photoreceptor. The present invention relates to heat fixing temperature control in an electrostatic recording device such as a recording device that forms a latent image on a surface or a dielectric surface, develops it, and transfers it to recording paper.

One of this type of recording apparatus is shown in FIG. 1a, and to explain it, one of the operations of the electrophotographic type shown in FIG. 1a is the following copying operation.

(1) Charging: Gives an electric charge to the photoreceptor.

(2) Exposure: Forms an electrostatic latent image on the photoreceptor.

(3) Development: Apply toner to the electrostatic latent image to form a visible image.

(4) Transfer: Transfer the toner image on the photoreceptor to copy paper, and (5) Discharge: Eliminate the residual charge on the photoreceptor to prepare for the next copying operation.

To explain these with reference to the configuration shown in Fig. 1a, the light reflected from the document IP by the emitted light from the illumination lamp HLA is transmitted to the drum by the first mirror FMI, the second mirror SMI, the in-mirror lens IMI, and the third mirror TMI. 1 to the surface of the photoreceptor. On the other hand, the photoreceptor is uniformly charged by the main charger 2, and is exposed to the guided light to form an electrostatic latent image. This electrostatic latent image is made visible by depositing charged toner supplied by the developing device 4. On the other hand, the copy paper is fed by the paper feed roller.
Cassette CAS1 or PSR1 or PSR2
Retrieved by CAS2. The taken-out copy paper is sent to the transfer section by rotating the registration rollers 6 in synchronization with the position of the latent image (the edge of the document). In the single copy section, the toner adhering to the latent image area is transferred onto the copy paper by the transfer charger 7, the copy paper is separated from the drum 1 by the separation roller 8, and the toner is brought into close contact with the copy paper by the fixing heater TEP. (fixed) and the copy paper is sent to the output tray COT. On the other hand, the toner remaining on the drum 1 is neutralized by a static eliminating charger 5 and collected by a cleaning roller 10. 11 is a cleaning blade. The document reading scanning system includes illumination light HLA, mirror FMI, SMI,
and a carriage that moves them in the direction of the solid arrow without changing the optical path length.
FIG. 1b shows the operation timing of each part shown in FIG. 1a. The copying apparatus shown in Fig. 1a is not a type that copies the entire surface at once, but a slit exposure type, and the positions of charging, exposure, development, and transfer are shifted, as shown in Fig. 1b. Each part is energized in sequence. The actual copying operation is started by the copy start signal A obtained by pressing the copy button, etc., and the main charger 2 is energized, thereby setting the time t ₀ - t ₁ until the charging position reaches the exposure position. ing. This is because in an actual machine, a certain amount of time is required from when the carriage carrying the scanning optical system starts operating until it actually reaches the position where it starts reading the document, and this time varies. . For that reason,
Considering this variation, the main charger 2
The carriage is made to start moving forward after ₁ hour t ₀ -t has elapsed since the energization. and document edge signal E
After this is detected, exposure F, development bias G, registration roller drive H, transfer charge bias I, carriage advancement, etc. are performed. The backward movement J of the carriage continues after the time period for the carriage forward movement has elapsed until a Home signal K indicating that the carriage has reached its initial position is output. Further, the feed and end rollers C are driven and energized by the copy start A, thereby feeding the end of the copy paper to the registration rollers 6.

When continuous copying is set, the next copying operation is started at the rise of the Home signal K. In other words, Home
Copy start A using the differentiating circuit at the rising edge of signal K
A pulse similar to that of is generated, and control signals from main charger B onward are created based on this pulse.

Further, as shown in FIG. 1a, in addition to the original image projection optical system, a CCD element 16 and an OFT which are photoelectric conversion devices that convert image information of the original into electrical signals are shown.
(optical fiber tube) 3, the half mirror 14, lens 15, and CCD element 16 convert the optical signal of the original image into an electrical signal, and add the image signal to the OFT 3.
The photosensitive drum 1 can be operated as a facsimile image reading and recording device by projecting optical information onto the photosensitive drum 1 from the face plate of the photosensitive drum 1, or can be used for copying by projecting an original image in the same way as the copying device shown in FIG. 1a described above. During this copying, other image signals or image signals read by the CCD element 16 and subjected to edge compensation may be added to the OFT for double recording. In such a copying apparatus, when reading an original image and obtaining an image signal from the CCD element 16, the light source HLA, the first and second mirrors FMI,
Only the optical system made of SMI needs to be scan-driven by a carriage. Also, when copying, to prevent the face plate of OFT3 from getting dirty,
Slide the OFT holder 12H and place the OFT 3 in the retracted position. In the case of recording only by energizing OFT3, the carriage is kept stationary and the main charger 2 and below are operated in the same way as when copying, but the exposure position of OFT3 is different from the exposure position by mirror TMI, and the recording operation speed is It may be preferable to change it from when copying. When the copying operation and the exposure by the OFT 3 are combined, a sequence control signal is required to match the exposure position by the mirror and the exposure position by the OFT 3.

These sequence control signals and timing pulses are created by the central control unit (consisting of a microcomputer) of the electrical equipment section 17 based on state change signals and clock pulses obtained from each part of the mechanism.

Conventionally, the temperature control of the fixing device HEP started by energizing heating elements such as resistance wires, infrared light emitting tubes, and infrared sheathed heaters when the power was turned on, and then the fixing was performed using a temperature sensor provided in the fixing unit. Feedback control is performed in which the temperature is detected, and when the temperature exceeds a predetermined value, the heating power is cut off or reduced, and when the temperature falls below the predetermined value, the heating power is turned on or increased. The fixing device shown in FIG. 1a is composed of an infrared heater 18, a cylindrical metal roller 19b coated with heat-resistant rubber or Teflon coating 19a, a back-up roller 20, and a temperature sensor 21, as shown in FIG. 1c. be done. As with a normal heating device, after the temperature sensor 21 detects a low temperature and supplies power to the infrared heater 18, or increases the applied power, In other words, there is a delay time before a predetermined temperature rise appears on the surface of the metal roller 19b (which may be regarded as the surface of the metal roller 19b), large temperature changes, poor fixing (when the temperature is low), wasted power, and the coating 19a. toner adhesion (when the temperature is high). To explain this with reference to FIG. 1d, when the power is turned on, the heater 18
After a considerable delay time t _d has elapsed, the surface temperature of the coating 19a begins to rise, and when the surface temperature reaches t ₁ (point A: time t ₁ ), the energization is stopped, but due to t _d The surface temperature increases further. Then, after t ₁ + t _d , the temperature gradually decreases due to heat radiation, and when it reaches T ₂ (point B: time t ₈ ), the heater 18 is energized, and when it reaches T ₁ (point C), the energization is stopped. The temperature of the coating 19a and the metal roller 19b changes as shown by the solid line. This is the case when no copy operation is performed.

When the developing temperature reaches T ₁ (point A), the heater lamp goes out and the start switch button changes to blue, indicating that copying is possible (this only happens when T ₁ is reached for the first time after the power is turned on). Therefore, when the operator immediately presses the start switch button to start copying, the recording paper absorbs heat during fixing, so the temperature does not rise as shown by the solid line, as shown by the two-dot chain line _L1 . Note that _t1 - _t2 is the time during which the recording paper passes through the fixing heater HEP. Further, to simplify the explanation, the time from when the start switch button is pressed until the recording paper reaches the fixing heater HEP is ignored in FIG. 1d. However, if copying is started at time _{t3, when the temperature is at its highest, instead of at time t1 when T1} has been reached, the fusing temperature is particularly high while the leading edge of the recording paper passes through the HEP.
Fixing is performed at a temperature above the setting range T ₂ (line L ₂ ). On the other hand, when the copying operation is started at t ₇ just before point B (t ₈ ) at which the heater 18 is energized again, the surface of the heater 19a becomes less than T ₂ due to heat absorption by the recording paper, and the heater 18 starts, but since there is a delay of t _d before the temperature rises, fusing is performed at a temperature below the setting range T ₁ , as shown by line L ₃ , and in this case, the energization starts at D.
Since the process from point to point E is carried out over a long period of time, the temperature rises significantly after passing point E.
When the copy operation is started when it is maximum,
Fixation occurs at a temperature of T ₁ or higher. Also, if you start the copy operation at time t ₃ and then start the copy operation at time t ₅ , as shown by line L ₄ ,
Fixing occurs at a temperature of less than T ₂ , and then when fixing is started at time t ₆ (double-dashed line), fixing occurs at a temperature of T ₁ or higher.

As described above, the fixing temperature varies greatly depending on at what point in the feedback control of the heater 18 the copying operation is started. This is mainly a feedback control in which there is a response delay of the fixing device itself and a total control delay of the sensor 21 and the power controller, _td , and even though it is a control system that should be stably controlled with a relatively long transmission time. Regardless, the arrival of the recording paper, which is a heat absorber, acts as a sudden disturbance on the control system, causing a rapid temperature change.

The present invention aims to reduce the drop in fixing temperature due to the absorption of heat by the recording paper while the recording paper passes through the fixing device, and to make the fixing temperature applied to the recording paper constant while passing through the fixing device, that is, to prevent a minute drop in the fixing temperature. The purpose is to prevent.

In order to achieve the above object, in the present invention,
Let t _d be the delay time from when power is applied to the heating element of the fixing device until the resulting rise in fixing temperature appears, then t _d is longer than the time the recording paper reaches the fixing section.
Electric power is applied to the heating element to compensate for the decrease in fixing temperature due to heat absorption by the recording paper.

In the fixing device shown in FIG. 1c and other fixing devices that use a heating element, the delay time T _d is determined by applying power to the heating element in a predetermined cycle on and off while the part that applies heat to the recording paper is forcibly cooled. or by controlling the power in a sinusoidal manner.
It can be easily determined by monitoring the detected value of the temperature sensor 21, comparing the power on/off timing or the peak value of the sine wave power, and the peak value of the detected temperature, and finding the deviation t _d of the temperature change with respect to the power change.

The delay time t _d of the fixing device used in a normal copying device is smaller than the time t _K from when the copy start signal A (Figure 1b) appears until the leading edge of the recording paper reaches the fixing device. Therefore, after tK- _td after the appearance of the copy start signal _A , it is sufficient to apply electric power to the heating element to compensate for the temperature drop due to the heat absorption of the recording paper. Signals other than signal A can be similarly used to determine the timing reference point, as long as they exhibit a signal change t _d or more before the time when the recording paper reaches the fixing device HEP.

The amount of heat absorbed by the recording paper varies depending on the type (material) and size of the recording paper, the amount of toner on the recording paper, and the temperature (more precisely, the difference between the temperature of the fixing section and the temperature of the recording paper). It also changes depending on the size of the feeding speed of the recording paper, but since the feeding speed is usually constant, this is ignored here. Therefore, in order to more accurately control the fixing temperature, it is preferable to determine the amount of power to be administered according to these parameters.

On the other hand, not only is heat removed from the fusing unit by the recording paper, but heat is also lost through heat dissipation from the fusing unit itself, and the amount of heat mainly depends on the room temperature (more precisely, the difference between the temperature of the fusing unit and the room temperature). do. Therefore, even after the fixing temperature is once set to a predetermined temperature, power is continuously or intermittently applied to the heating element to compensate for the heat dissipation of the fixing unit itself. Simply put, power is given to the heating element as base power to compensate for the heat dissipation of the fixing unit itself, and when a base signal such as the copy start signal A arrives, the amount of heat absorbed by the recording paper is increased at the timing t _K - t _d mentioned above. Just add the corresponding amount of power. Such power-on control is preferably gate-on phase control using a phase control element rather than controlling the power-on time in an on-off manner. This is because in on-off power control, when the base power input and the recording paper heat absorption compensation power input overlap, this is done by adding the switch-on time or by controlling the amplitude of the voltage or current value using a resistor, transformer, etc. Although it has to be done, amplitude control not only complicates the circuit equipment but also has the problem of large power loss.Adding the switch-on time requires doubling the power at the same point in time, but it is difficult to do so over time. This is undesirable because of the presence of t _d . On the other hand, in phase control, when recording paper heat absorption compensation is required, it is only necessary to change the trigger phase angle for turning on the base power to a trigger phase angle that takes the heat absorption compensation into consideration. Another method is to set the recording paper heat absorption amount compensation power to include the heat dissipation compensation power of the fixing unit itself, and at the timing t _K - t _d , the phase angle of the base power control is changed to the phase angle of the recording paper heat absorption amount compensation power control. Just switch it to the corner.

As explained above, since the control method of the present invention is program control, it may naturally deviate from the target due to the way parameters are taken, approximations, etc., and it may also be disturbed by disturbances that have not been introduced into the program. sell. Therefore, as a dependent control method, it is preferable to perform a protective operation based on temperature detection by a temperature sensor, and/or to use feedback control similar to the conventional method in combination as a dependent control. In the protective operation, when a high temperature T _ab outside the temperature sensor fixing temperature range is detected, base power control and heat absorption compensation power control are cut off until the lower limit of the temperature range T ₂ is reached, and after reaching T ₂ , they are stopped. In feedback control, when the temperature sensor detects the upper limit _T1 of the fixing temperature range, the phase angle of base power control and/or recording paper heat absorption amount compensation power control is shifted one rank smaller. , when the lower limit T ₂ is detected, the phase angle is shifted one rank larger.

The control operations described above are stored as constant data and temperature control program data in the read-only memory (ROM) of the microcomputer system that makes up the temperature control central unit, and are accessed using parameters that change the fusing temperature. It is preferable to read out the phase angle or electric power, and control the heating of the heating element based on this. Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 2a shows an example of an apparatus configuration for implementing the present invention. In FIG. 2a, 22 is a microcomputer system used as a main control unit to control the fixing temperature, and an input/output port 22
a, ROM22b, central processing unit (hereinafter referred to as CPU)
) 22c, a read/write memory (RAM) for a data register, and a clock pulse generator 22e.

The input/output port 22a has a binary code representing the fixing temperature detected by the temperature sensor 21, a binary code representing the room temperature, a binary code representing the set number of copies, and a binary code representing the number of copies (the number of completed copies). decimal code, code (2 bits) representing recording paper type (3 types: thick, normal, tracing paper), recording paper size (4 types: A3, B4, A4, B5)
A code (2 bits) representing the image density (3 types: large black part of the original image, normal, small), a signal (pulse) representing power on, a signal representing the start of copying operation (pulse),
A first interrupt signal that becomes high level "1" when the temperature T _X detected by the temperature sensor 21 exceeds the upper limit of the set range, and a second interrupt signal that becomes high level "1" when _T 2 interrupt signal is given to the temperature control circuit 23 from the input/output port 22a.
is given a binary code representing the trigger phase angle. The set number of copies, recording paper type, size, and image density are set by the operator's operation on the keyboard of the copying machine and are given to the control unit 22 from the keyboard, and the number of copies is given to the control unit 22 from the central control unit of the copying machine, Room temperature T _R is given by a room temperature sensor. The ROM22b contains the first
As a constant table, when the power is turned on, the sensor 21
Difference between detected temperature T _X and target temperature T ₀ , T ₁ <T ₀ <T ₂ ,
Each activation trigger phase for various types _of T _{0 -T} When T ₀ - T 〓, (starting trigger phase) × in order to switch to the trigger phase for saturation stabilization
The trigger phase for saturation control for (starting time until T ₀ −T〓) is stored in memory. Also
The ROM 22b stores, as a third constant table, a trigger phase angle that compensates for the heat dissipation of the fixing unit itself for the difference between the target fixing temperature T ₀ and the room temperature _TR (this is the temperature of the recording paper storage section in the copying machine). Trigger phase angles for compensating the amount of heat absorbed by the recording paper with respect to the recording paper type, size, image density, and paper temperature (regarded as T _R ) are stored as a fourth constant table. This memory address has a total of 6 bits: 2 bits representing the recording paper type, 2 bits representing the size, and 2 bits representing the image density, and the number of data is 3 types of recording paper x 4 types of size x image density. 3 types = 36. These 36 data are all at room temperature, T _R =15-20°C. For correction when T _R is out of this range, a fifth constant table is stored in the ROM 22b to set the recording paper temperature T _R to less than 0°C, 0 to 5°C.
10 categories: less than 5 to less than 10℃, 10 to less than 15℃, 15 to less than 20℃, 20 to less than 25℃, 25 to less than 30℃, 30 to less than 35℃, 35 to less than 40℃, and 40℃ or more year,
Correction coefficients for each of these categories (T _R = 15 to 20
1) is stored in memory when the temperature is ℃. In addition to these constant tables, the ROM 22b stores program data for controlling the temperature described below, and the CPU 22c reads out the program data in the ROM 22b in response to a power-on signal and reads each constant table. See heater 18
A trigger phase angle for controlling energization is given to the temperature control circuit 23 in the form of a binary code. The temperature control circuit 23 includes a D/A converter 23a that converts a binary code into an analog signal voltage, and a trigger pulse generation circuit that provides a trigger pulse to the gate of a three-pole bipolar thyristor (TRIAT) 24 connected in series to the heater 18. 23, trigger pulse,
It is comprised of a phase control circuit 23b that sets the phase with respect to the AC input to a value corresponding to the output signal voltage of 23a, and a power supply circuit 23d that supplies circuit power to each of these elements. Since the circuit 23 except for the D/A converter 23a is well-known in the gate trigger control of thyristors, a detailed explanation will be omitted. The heater 18 is connected in series with the aforementioned triac 24 and a temperature fuse 25 to a constant voltage AC power source. The output of the temperature sensor 21 is once amplified and applied to the A/D converter 26 and the differential amplifiers 27 ₁ and 27 ₂ . The differential amplifier ₂₇₁ calculates the temperature _Tx represented by the output of the sensor 21.
When the fixing temperature exceeds the upper limit T ₁ , the output _changes to " ₁ ", and when _T
The output changes to These "1" signals are given to the input/output port 22a as interrupt signals.

Next, the energization control of the heater 18 will be explained with reference to the flowchart shown in FIG. 2b. When the power-on signal arrives, the difference between the surface temperature T _X of the coating 19a and the target fixing temperature T ₀ at that time is calculated, and the activation trigger phase angle corresponding to this difference is read from the first constant table in the ROM 22b. In this case, for example, if T ₀ −T _X = 52℃, this is 50 to 55℃
, and the starting phase angle S for this rank is
_t is read from the first constant table of the ROM 22b and latched into a predetermined memory area (S _t register) of the RAM 22d. This data is then given to the temperature control circuit 23. As a result, when the value of T _{0 −T} Simultaneously with starting this energization, a time counting operation by a counter is started. Then, when T _x −T ₀ −T〓, that is, the coating
When the surface temperature of 9a becomes T〓 before the target value T ₀ , the amount of electricity input is calculated from the product of the current energization time (count value) and the energization current value (phase angle S _t ), and then The corresponding phase angle data S _S
Read from the second constant table of ROM22b
Specified memory area of RAM22d (S _S register)
is latched and applied to the temperature control circuit 23. In this case, if the amount of input electricity is large, a large temperature rise will appear after t _d , so S _S is assumed to have an extremely large phase delay, and S
_S is assumed to have a slightly smaller phase delay. In any case, rather than actively heating up _the heater 18, _{S S}
Temperature rise due to power input until 〓 (delay in t _d )
It is designed to provide a small amount of compensation power that does not reach T ₀ while maintaining the same power. As a result, as shown in Fig. 2e, the temperature _{T X} of 19a rises at _a relatively fast rate until T _{0 - T} However, t ₁ + t _d
It becomes very gradual later on. And T _X ≒ T ₀
That is, a copy ready signal is given to the central _control unit _of the copying machine when _{T 1} < _T
In other words, calculate the difference between the target temperature and the room temperature, read out the trigger phase angle S _B that compensates for the heat dissipation of the fixing device from the third constant table of the ROM 22b, and latch it in a predetermined memory area (S _B register) of the RAM 22d. and provides it to the temperature control circuit 23. As a result, the temperature T _X of 19a after that becomes T ₁ <T _X ≒
It is stable at T ₀ < T ₂ . Copy start signal A
When , the counter starts timing operation, and the phase angle S _A (T _R = 15° to 20
℃) from the fourth constant table in the ROM 22b and latches it in the RAM 22d, addresses the recording paper temperature T _R , reads the correction coefficient α from the fifth constant table in the ROM 22b, and latches it in the RAM 22d.
2d, and latches S _A ×α to RAM 22d. Then, when the count value becomes t _K -t _d , that is, after t _d , the leading edge of the recording paper is covered with 19
At the time when part a is reached, S _A ×α is applied to the temperature control circuit 23. As a result, the heater 18 is activated by the trial 24 at a phase angle that compensates for the heat absorption of the recording paper.
A trigger pulse is given to The temperature rise of the coating 19a due to this phase angle of S _A ×α occurs after t _d from the start of the process, that is, from the time when the leading edge of the recording paper reaches 19a, resulting in an increase in the amount of heat and recording The heat absorption of the paper is canceled out, and even while the recording paper passes through the section 19a, the temperature T of the section 19a remains constant.
_X is maintained at T ₀ .

After setting S _A +α, a time counting operation is started by the counter, and when the count value reaches t _p , that is, when the recording paper section 19a passes time, the operation returns to the natural heat radiation compensation operation after outputting the copy enable signal. During continuous copying, copying for the second and subsequent sheets is started at the rising edge of the Home signal K. Therefore, when the Home signal K rises, if the number of copied sheets < the set number of sheets, that is, If the set number of consecutive copies have not been completed, the aforementioned recording paper heat absorption compensation operation is started. In this way, during copying, the timing is determined by the feeding of the recording paper and the response delay _td of the fixing temperature, and the amount of heat for endothermic compensation is applied to the section 19a only while the recording paper passes through the section 19a, and at other times. Since the heat dissipation of the fixing device is compensated for, the heat balance between the amount of heat escaping from the fixing device and the amount of heat input to the fixing device is at the same timing at section 19a at any point in time, so changes in the fixing temperature will not occur. This is extremely small, and the copy start timing is independent of the fixing temperature.

Next, Fig. 2c and _{2d show} the control operation when the fixing temperature _T This will be explained with reference to the flowchart shown in the figure. First, to explain the premise, the system 22 has a ROM 22b
According to the program data, the outputs of the differential amplifiers 27 ₁ and 27 ₂ are set to be viewed after outputting the copy enable signal. In _other words, after setting _{T X} to T ₁ < T ₀ < T ₂ and _T
27 The output of ₂ is to be viewed. If the temperature goes out of control before then, the temperature fuse 25 will blow, and if the temperature does not heat up, the copy enable signal will not be output and the ready lamp will not light up.

27 When the output of ₁ becomes “1” (Figure 2c),
_In other _words , if _T Check whether continuous copying is set or not, and if continuous copying is set, a flag indicating that rank No. R (see step in Figure 2b) is latched is set in a predetermined area (R register) of RAM 22d. See if it's standing or not. If you are standing there, one or more sheets of continuous copying has already been completed, or the first sheet of recording paper is about to be sent to 19a. Therefore, since fixing will occur at a high temperature if left as is, and there is a high probability that the recording paper heat absorption amount compensation will be too large, 1 is added to R. This means a readout change in which constant data whose heating amount is one rank lower than the constant data (phase angle) stored in R is read out. As a result, the tri-attack 24 is triggered at a phase angle that is later than that set as constant data in advance, and overheating of the recording paper is prevented.
Moreover, the temperature of 19a is lowered by the recording paper. The same operation is performed before fixing the next recording paper if T _X ≧T ₁ . Therefore, even after one sheet of recording paper has passed, if T _X ≧T ₁ , the compensation power for each recording sheet is lowered until T _X <T ₁ , and T _X decreases. When continuous copying is not set, there is a high probability that the amount of power compensated for natural heat dissipation is large, so 1 is added to B of rank No. B (see step in Fig. 2b). This means a readout change in which constant data whose heating amount is one rank lower than the constant data stored in B is read out. 27 When the output of ₂ is “1”, that is, when T _X ≦T ₂ , the above-mentioned _T
Just change it in the opposite way to when ≧T ₁ . That's the second
Shown in Figure d.

As described above, in the present invention, when t _d is the delay time from when power is applied to the heating element of the fixing device until the fixing temperature rises due to this, the delay time is approximately t _d before the recording paper reaches the fixing section. Since power is applied to the heating element to compensate for the decrease in fixing temperature due to heat absorption of the recording paper, when the recording paper begins to enter the fixing device, the temperature of the fixing device rises just enough to compensate for the decrease in temperature due to the heat absorption of the recording paper. Therefore, the recording paper has substantially the same fixing temperature from its leading edge to its trailing edge. In other words, a decrease in fixing temperature is avoided.

[Brief explanation of the drawing]

FIG. 1a is a side view showing one of the recording devices to be controlled by the present invention, and FIG. 1b is a time chart showing control signals for controlling the operation of each part thereof.
Figure 1c is an enlarged sectional view of the fixing device HEP, Figure 1d
The figure is a graph showing fixing temperature fluctuations in a conventional fixing temperature control method. FIG. 2a is a block diagram showing one apparatus configuration for implementing the present invention, FIG. 2b
2c and 2d are flowcharts showing the operation sequence, and FIG. 2e is a graph showing the change in fixing temperature in the method of the present invention. 1: Photosensitive drum, 2: Main charger,
3: OFT, 4: Developing device, 5: Static elimination charger, 6: Registration roller, 7: Transfer charger,
8: Separation roller, 9: Transfer paper transfer line, 10:
cleaning roller, 11: cleaning blade, 12H: OFT holder, 13: substrate, 17:
Electrical component, 18: Infrared heater, 19a: Coating, 1
9b: Metal roller, 20: Backup roller,
21: Temperature sensor, 22: Microcomputer system, 23: Temperature control circuit, 24: 3-pole bidirectional thyristor, 25: Temperature fuse, 27 ₁ ,
27 ₂ : Differential amplifier.

Claims (1)

[Claims] 1. Delay time t from when power is applied to the heating element of the fixing device until a rise in fixing temperature appears due to this.
_d , a fixing temperature control method for a recording apparatus in which power is applied to the heating element to compensate for a decrease in fixing temperature due to heat absorption of the recording paper approximately t _d before the recording paper reaches the fixing unit. 2. A fixing temperature control method for a recording apparatus according to claim 1, wherein the electric power for compensating for a decrease in fixing temperature due to heat absorption of the recording paper is changed according to the type, number and size of the recording paper. 3. A fixing temperature control method for a recording apparatus according to claim 1, wherein the power for compensating for a decrease in fixing temperature due to heat absorption of recording paper is changed depending on the amount of document image information. 4. The fixing temperature of the recording device according to claim 1, 2, or 3, in which power is continuously or intermittently applied to the heating element to compensate for the decrease in fixing temperature due to heat dissipation of the fixing device itself. Control method.