JPH1010951A - Image recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the recording of high quality capable of performing the fixing operation to a recording medium such as a recording sheet, at a constant temperature, while preventing the unnecessary power consumption, by installing a means for predicting the time from the preheating condition to the fixing temperature, and supplying the recording medium such as the recording sheet corresponding to the predicted recording start timing (time). SOLUTION: A temperature of a fixing roller is increased by switching a heater on from the write start time A. In this case, the paper conveyance is started at the time B (paper supply timing) when the temperature reaches the predetermined temperature D (paper supply temperature), while considering the time (B-C) necessary for the paper to reach the fixing roller. Then the temperature of the fixing roller will reach the fixing temperature E at the time C when the paper reaches the fixing roller. The on/off control of the heater is performed, so that the temperature of the fixing roller is kept at the fixing temperature E.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus such as a facsimile machine, a copying machine, and a multifunction facsimile / copy machine, and more particularly to temperature control during thermal fixing of toner and the like in an electrophotographic process.

[0002]

2. Description of the Related Art In an electrophotographic process of an image recording apparatus, a heater is used to control the temperature of a heat fixing device. As a characteristic of this heater, the surface temperature per fixed time is proportional to the power supply voltage. Also,
The power supply voltage may fluctuate depending on the installation area of the device. For example, there is an area such as a European area where there is a fluctuation of about 20 to 30 V. However, since the temperature at which writing starts must be set at the center voltage or the lower limit, in an installation environment where the power supply voltage is low,
There is a disadvantage that the temperature is lower than the temperature assumed at the time of design. Conversely, in an installation environment where the power supply voltage is high, there is a problem that the temperature becomes higher than assumed at the time of design, and power is wasted.

A heat fixing device of this image recording apparatus is usually
It is heated at a certain level of temperature so that the recording operation can be started immediately if necessary (preheating standby). In this case, the preheating standby temperature can be arbitrarily set as long as recording can be started in a short time. However, this preheating standby temperature must also be set at the center voltage or the lower limit, so in an installation environment where the power supply voltage is high,
The temperature is higher than necessary, and as a result, power consumption is wasted. A temperature sensor is used for controlling the temperature of the heat fixing device. However, at the start of recording, when the temperature is raised from the preheating standby temperature to the fixing temperature, if there is a response delay due to the characteristics of temperature detecting means such as a thermistor used as a temperature sensor, the actual surface temperature is detected. It is assumed that the temperature will be higher than the temperature.

One method of controlling the temperature of these heat fixing devices is to control the temperature of the heat source to reach an initial fixable temperature higher than a normal fixable temperature at which the sheet can be fixed when the heat source is started. By doing so, a control technique for improving the fixing rate at the time of startup is known (for example, JP-A-5-150576). According to this temperature control technique, the heat fixing rate at the time of startup is improved, but power consumption and the like are not particularly considered.

[0005]

As described in the prior art, the power supply voltage for driving the image recording apparatus slightly varies from the nominal value depending on the region where the image recording apparatus is used. for that reason,
When used in a state different from the power supply voltage at the time of design, the temperature at the start of recording fluctuates, and there is a problem that the temperature at the start of writing cannot be accurately controlled. According to the present invention, the temperature at the time of fixing can be controlled to a predetermined value irrespective of the fluctuation of the power supply voltage, thereby preventing wasteful power consumption and fixing the recording medium such as recording paper at a constant temperature. A first task is to enable operation.

Further, when the power supply voltage fluctuates, the same effect is exerted on the preheating standby temperature. When the power supply voltage is higher than the power supply voltage at the time of design, the power consumption is wasted. In the present invention, the preheating temperature in the standby state is set in consideration of the fluctuation of the power supply voltage so that the recording operation can be started within a predetermined time and the power consumption can be reduced. Make it an issue.

A temperature sensor (temperature detecting means) is used for controlling the temperature of the image recording apparatus. However, in the case of a temperature detecting means such as a thermistor, the response characteristics of the temperature detecting means are delayed. The surface temperature differs from the detected temperature. Therefore, there is a problem that when the temperature is raised from the preheating standby temperature to the fixing temperature, the heating is performed to a temperature higher than a predetermined fixing temperature. A third object of the present invention is to realize a heater energization control in consideration of a delay time of a response characteristic of a temperature detecting unit such as a thermistor so that a surface temperature of a fixing roller does not excessively increase.

[0008]

According to the first aspect of the present invention, there is provided an image recording apparatus for forming an image such as a character or a figure by fusing toner to a recording medium such as recording paper by a fixing roller and a pressure roller. In the fixing device, a temperature detecting unit such as a thermistor for detecting the surface temperature of the fixing roller, a temperature detected by the temperature detecting unit in a standby state other than the recording operation, and a heater ON / OFF control state are determined in advance. A time estimating means for estimating the time from the preheating state to the temperature at which the fixing can be performed is provided, and a recording medium such as recording paper is supplied in accordance with the estimated recording start time.

According to a second aspect of the present invention, in the thermal fixing device of the image recording apparatus according to the first aspect, a temperature detecting means such as a thermistor for detecting a surface temperature of the fixing roller and a temperature detecting means in a standby state other than the recording operation. The temperature detected by
A time estimating means for estimating a time from when the heater is turned on / off to when the temperature reaches the feasible temperature from the preheating state, and a standby state such that the recording operation can be started within a predetermined time; The preheating temperature in the state is controlled.

According to a third aspect of the present invention, in the thermal fixing device of the image recording apparatus of the first aspect, a temperature detecting means such as a thermistor for detecting a surface temperature of the fixing roller and a temperature detecting means in a standby state other than the recording operation. The temperature detected by
A time estimating means for estimating a time period from a heater on / off control state to a pre-heated state to a feasible temperature in advance to prevent the surface temperature of the fixing roller from rising above a prescribed temperature due to overshoot. After a lapse of a predetermined time after the elapse of the predicted time, the heater is turned off.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

1. Configuration and Operation of Image Recording Apparatus The present invention relates to temperature control of an image recording apparatus, particularly a heat fixing apparatus. First, the overall configuration of a facsimile apparatus as an example of the image recording apparatus of the present invention will be described.

FIG. 1 is a functional block diagram showing an example of an embodiment of a main part configuration of a facsimile apparatus which is an example of an image recording apparatus according to the present invention. In the figure, 1 is a main control unit, 2 is an operation display unit, 3 is an NCU unit (network control unit), 4 is a modem, 5 is a DCR unit (encoding / decoding unit), 6 is a recording unit (plotter), 7 Denotes a reading unit (scanner), and 8 denotes a system bus.

The facsimile apparatus shown in FIG. 1 performs thermal fixing of toner or the like in the recording section 6, but has a basic configuration similar to that of a conventional apparatus. The function of each part is roughly as follows. The main control section 1 performs control processing of each section and a facsimile transmission control procedure in the heat fixing device of the image recording apparatus of FIG. The operation display unit 2 has a function of performing a communication operation, a registration operation, and the like, and includes various keys and a display. The NCU unit (network control unit 3) is a control unit for connecting to a public telephone line network, an ISDN line, or the like.
It also has an automatic calling and receiving function. The modem 4 is, for example, G3
It has a function of realizing a facsimile modem function, and modulates and demodulates a signal to be transmitted.

A DCR unit (encoding / decoding unit) 5 encodes and compresses raw image data (image information before encoding) according to a predetermined method, or converts an encoded image into original raw image data. It has the function of elongation. The recording unit (plotter) 6 is an output unit such as a printer that records and outputs images or reports at a predetermined resolution. The reading unit (scanner) 7 is an image input unit that reads a document at a predetermined resolution. The above is the configuration and functions of the facsimile apparatus which is an example of the image recording apparatus. Next, the heat fixing device will be described.

FIG. 2 is a schematic side view showing an example of a detailed configuration of the heat fixing section provided in the recording section 6 shown in FIG. In the figure, 11 is a thermostat, 1
Reference numeral 2 denotes a paper discharge sensor, 13 denotes a pressure roller, 14 denotes a fixing roller, 15 denotes a thermistor, and P denotes a conveyed sheet.

FIG. 2 shows a thermal fixing device of an image recording apparatus.
As shown in FIG. 2, the pressure roller 13 and the fixing roller 14 are arranged to face each other. The toner on the latent image formed on the sheet P in a developing step (not shown) is fused by the heat of the fixing roller 14 and the pressure of the pressure roller 13 to form an image on the sheet P. The thermostat 11 controls energization of a heater of the fixing roller 14. Thermistor 15
Detects the surface temperature of the fixing roller 14.

FIG. 3 is a functional block diagram showing a configuration of a temperature detecting system for detecting the surface temperature of the fixing roller 14 shown in FIG. In the figure, 15 is a thermistor, 16 is A /
D converter 17 indicates a CPU processing unit.

The output of the thermistor 15 is A / D-converted by an A / D converter 16 and is converted to a digital output by a C / D converter.
The information is transmitted to the PU processing unit 17. In the CPU processing unit 17,
The on / off control of the heater is performed with reference to the value of the digital output to maintain a constant fixing temperature. The above is the outline of the configuration and operation of the image recording apparatus and the heat fixing device.

Temperature Control in Recording Operation and Timing of Feeding Out Paper As described above, the fixing roller 14 is maintained at a predetermined temperature in a standby state other than the time of writing (preheating temperature). At the time of writing in the recording operation, the heater is turned on from the start point, the temperature of the fixing roller 14 is raised, and the paper is fed out at the timing when the fixing temperature is reached.

FIG. 4 is a time chart for explaining an example of the relationship between the temperature change state of the fixing roller 14, the start of writing, and the timing of feeding out the sheet in the image recording apparatus of the present invention. In the figure, the horizontal axis represents time, the vertical axis represents temperature, A is at the start of writing, B is at the time of feeding the paper, C is
Indicates the time when the sheet reaches the fixing roller, D indicates the sheet feeding temperature, and E indicates the fixing temperature.

As an operation at the time of writing, as shown in FIG. 4, the heater is turned on from the writing start point A, and the temperature of the fixing roller 14 is raised. In this case,
At time B (sheet feeding timing) when the temperature reaches a preset temperature D (sheet feeding temperature) in consideration of the time (B to C) required for the sheet to reach the fixing roller 14, the sheet conveyance is started. Thereafter, at the time point C when the sheet reaches the fixing roller 14, the temperature of the fixing roller 14 reaches the fixing temperature E. On / off control of the heater is performed so that the temperature of the fixing roller 14 is maintained at the fixing temperature E. In a standby state other than the time of writing, a predetermined preheating standby temperature is maintained, which does not require a long time from the writing start time A to the paper feeding time B. In this case, the time until the paper reaches the fixing roller 14 (B to B)
C) can be calculated from the distance from the paper standby position to the fixing roller 14 and the paper transport speed.

Calculation of Rate of Increase in Temperature of Fixing Roller In the image recording apparatus of the present invention, the rate of increase in surface temperature of the fixing roller 14 is determined, and the rate of increase in the temperature of the fixing roller
The time when the surface temperature of No. 4 reaches the fixing temperature E (FIG. 4) is predicted, and the paper is conveyed so that the recording operation is started at that time. In this case, the temperature in the standby state (preheating standby temperature) is used as a reference. Here, the rate of increase in the temperature of the fixing roller will be described.

FIGS. 5A and 5B are diagrams for explaining the relationship between the temperature change in the standby state and the heater-on state in the thermal fixing device. FIG. 5A shows the case of the power supply voltage a, and FIG. 5B shows the case of the power supply voltage b. In the figure, the horizontal axis represents time, the vertical axis represents temperature, F and F 'represent standby temperatures, and G and G' represent upper limit temperatures.

FIG. 5 shows a case where the relationship with b is a <b. For example, in the case of the power supply voltage a shown in FIG. 5A, if the current temperature is lower than the set standby temperature F, the heater is turned on. Conversely, if the current temperature is higher, the heater is turned on. Turn off. The maximum temperature in this case is G
When the current temperature reaches the upper limit temperature, the heater is turned off. Such on / off control of the heater is the same in the case of FIG. 5 (2). This figure 5 (1)
In (2), regarding the on / off state of the heater shown below, the upper limit temperature G or G 'during the cycle,
The values of the power supply voltages a and b can be estimated from the ON / OFF intervals. Generally speaking, the higher the power supply voltage, the higher the upper limit temperature and the shorter the on-time. For example, FIG.
Comparing (1) and (2), the on-time of the heater shown in Fig. 5 (2) is shorter than the on-time of the heater of Fig. 5 (1). It can be seen that b is higher than the power supply voltage a in FIG. Also, the relationship between the upper limit temperatures G and G 'is that the upper limit temperature G' of the power supply voltage b in FIG. 5 (2) is higher than the upper limit temperature G of the power supply voltage a in FIG. 5 (1). Is also getting bigger. From these relations, the rate of increase of the surface temperature of the fixing roller 14 is expressed as: increase rate = (upper limit temperature−
(Preheating standby temperature) / heater ON time. Next, a flow of calculating the temperature rise rate of the fixing roller described above will be described.

FIG. 6 is a flowchart showing the flow of main processing when calculating the temperature rise rate of the fixing roller in the image recording apparatus of the present invention. In the figure, #
1 to # 7 indicate steps.

First, in step # 1, it is checked whether the current temperature is lower than the standby temperatures F and F '. When the current temperature is not lower than the standby temperatures F and F '(when it is higher than the standby temperatures F and F'), the process proceeds to step # 4. On the other hand, when the current temperature is equal to or lower than the standby temperatures F and F ', the heater is turned on in the next step # 2. After accumulating the heater ON time in step # 3, the process returns to step # 1 again to check whether the current temperature is equal to or lower than the standby temperature F or F '. And
When it is detected in step # 1 that the current temperature is not lower than the standby temperatures F and F '(is higher than the standby temperatures F and F'), the process proceeds to step # 4.

At step # 4, the heater is turned off.
In the next step # 5, it is checked whether the current temperature is equal to or lower than the standby temperatures F and F '. If the current temperature is not lower than the standby temperatures F and F '(when the temperatures are higher than the standby temperatures F and F'), the process proceeds to step # 6, where the upper limit temperatures G and G 'are updated, and then the previous step # 6 is performed again. Returning to step 5, it is checked whether the current temperature is equal to or lower than the standby temperatures F and F '.
If it is detected in step # 5 that the current temperature is not lower than the standby temperatures F and F '(higher than the standby temperatures F and F'), the process proceeds to step # 7. In step # 7, the rate of increase is obtained by the above-described calculation formula, and the flow of FIG. 6 ends. Through the processing in steps # 1 to # 7, the rate of temperature rise of the fixing roller is obtained.

For example, the preheating temperature (standby temperature F, F ') in the standby state is 80 ° C., and the heater is turned on for 100 msec.
It is assumed that the upper limit temperature (G, G ′) at that time is 85 ° C. In this case, the preheating standby temperature F (or F ′) = 80 ° C., the upper limit temperature G (or G ′) = 85 ° C.,
Since the ON time of the heater = 100 msec, from the above equation of the rising rate, the rising rate = (85−80) / 100 =
50 (° C./sec) is calculated.

First Embodiment The first embodiment corresponds to the first aspect of the present invention. The first embodiment is characterized in that the time from the preheating state to the temperature at which the fixing can be performed is predicted in advance, and a recording medium such as recording paper is supplied in accordance with the predicted recording start timing (time). have. For estimating the time from the preheating state to the temperature at which the fixing can be performed, the rate of increase in the temperature of the fixing roller 14 described above is used. Then, as described with reference to FIG. 4,
The sheet feeding temperature D is calculated from “time from sheet feeding to reaching the fixing roller 14” (B to C). When the heater is turned on and the temperature of the fixing roller 14 reaches the sheet feeding temperature D, the sheet is fed.

As a specific example, as before, the preheating temperature (standby temperature F) in the standby state is 80 ° C., the heater is turned on for 100 msec, and the upper limit temperature (G) at that time is 8 ° C.
Suppose it was 5 ° C. In this case, the rate of increase = 50 (° C.
/ Sec). Also, the time from when the sheet is fed out to when it reaches the fixing roller 14 (B to C in FIG. 4).
Is 1 second, and a condition such that the fixing temperature E is 180 ° C. is set. Under this condition, the start of the sheet feeding operation (time point B) is one second after the preheating temperature (one second after the heater is turned on). When this relationship is expressed by a mathematical formula, a time from when the heater is turned on to the fixing temperature E = (180−80) (° C.) / 50 (° C./sec)
c) = 2 (sec), and it takes 2 seconds. Since the time (B to C in FIG. 4) from the sheet feeding time B to the fixing roller 14 is 1 second, the sheet feeding time B is One second after the heater is turned on.

As described above, in the first embodiment, the temperature detecting means (15 in FIG. 2) such as a thermistor for detecting the surface temperature of the fixing roller and the temperature detecting means in the standby state other than the recording operation Time predicting means (FIG. 6) for predicting in advance the time from the preheating state to the feasible temperature from the preheated state based on the temperature detected by the control (standby temperatures F and F 'in FIG. 5) and the heater ON / OFF control state. For example, a main control unit 1) of FIG. 1 is provided to supply a recording medium such as recording paper (B of FIG. 4) in accordance with the predicted recording start time (C of FIG. 4). I have to. Therefore, according to the first embodiment, even if the power supply voltage fluctuates somewhat, it is possible to set the power saving state in which the preheating standby temperature is always equal to or lower than the predetermined value. At the start of the operation, the paper can be supplied at a timing corresponding to the rise in the temperature of the fixing roller. In summary, it becomes possible to control the temperature at the time of fixing to a predetermined value regardless of the fluctuation of the power supply voltage. As a result, wasteful power consumption is prevented, and a fixing operation can be performed on a recording medium such as recording paper at a constant temperature, so that high-quality recording can be obtained.

Second Embodiment This second embodiment corresponds to the second aspect of the present invention. In the first embodiment, the case where the power supply voltage fluctuates has been described. The second embodiment is characterized in that the preheating temperature in the standby state is controlled so that the recording operation can be started in a predetermined time even when the power supply voltage is low. If the power supply voltage is lower than the value at the time of design, the time until the paper feeding temperature is reached is delayed, so that the time until the recording operation is started is prolonged. Therefore, in the standby state other than the recording operation, the time from the preheating state to the fixing possible temperature is estimated from the temperature of the fixing roller 14 detected by the temperature detecting unit and the ON / OFF control state of the heater in the standby state, The preheating temperature in the standby state is controlled so that the recording operation can be started within a predetermined time. In this case as well, the rate of increase in the temperature of the fixing roller 14 is obtained by the calculation method described in the flow of FIG. 6, and the time required to reach the fixing temperature from the preheating temperature is the set recording start time. Change the preheating temperature (set the preheating temperature higher).

As a specific example, as described above, the preheating temperature (standby temperature F) in the standby state is 80 ° C., the heater is turned on for 100 msec, and the upper limit temperature (G) at that time is 8 ° C.
Suppose it was 5 ° C. In this case, the rate of increase = 50 (° C.
/ Sec). Also, the time from when the sheet is fed out to when it reaches the fixing roller 14 (B to C in FIG. 4).
Is 1 second, and a condition such that the fixing temperature E is 180 ° C. is set. Furthermore, the conditions from the start of recording to the writing (requirements until the start of the recording operation) are 1.5
sec. Under these conditions, the temperature rise of the fixing roller 14 during the required 1.5 seconds is 50 (° C./sec)×1.5 (sec) = 75.
(° C.), while the fixing temperature E is 180 ° C. Therefore, the preheating temperature in the standby state is (180−
75) = 105 (° C.). In this case, the paper may be fed at a timing of 130 ° C. 0.5 seconds after the preheating temperature. As described above, in the second embodiment, the recording operation can be started in a fixed time without being affected by the fluctuation of the power supply voltage. Therefore, excessive heating can be prevented, unnecessary power consumption can be avoided, and recording can be started within a predetermined time.

Third Embodiment This third embodiment corresponds to the third aspect of the present invention. In the third embodiment, when a delay occurs in the output of the thermistor 15 (FIG. 3) that detects the actual surface temperature of the fixing roller 14 after the heater is turned on, the delay is corrected. The feature is that control by accurate temperature detection is enabled.

FIG. 7 is a time chart for explaining the delay of the detection output of the thermistor which detects the surface temperature of the fixing roller 14. In the figure, the horizontal axis represents time, and the vertical axis represents voltage.
H is the fixing temperature, I is the actual surface temperature, J is the output of the thermistor, and K is the detection delay time.

As shown by the solid line I in FIG. 7, the surface temperature of the fixing roller 14 rises from the time when the heater is turned on, and when the temperature exceeds the fixing temperature H and reaches the upper limit temperature, the heater is turned off. . However, the output detected by the thermistor 15 is generated at the timing indicated by the broken line J in FIG. Therefore, a delay time K occurs between the actual surface temperature of the fixing roller 14 and the detection output of the thermistor 15. Therefore, the information of the delay time K is stored in, for example, a work memory in the main control unit 1 in FIG. 1 and held in a standby state. Then, at the start of the recording operation, the rate of temperature rise is determined by the calculation process described in the flow of FIG. 6, and the time difference between the detected temperature and the actual surface temperature is calculated. The actual surface temperature is estimated based on the calculated time, and when the estimated temperature reaches I indicated by a solid line in FIG. 7, the heater is turned off. To put it simply, the actual temperature of the fixing roller 14 is just before the detected thermistor output value by the held delay time K.

As a specific example, similarly to the above, the preheating temperature (standby temperature F) in the standby state is 80 ° C., the heater is turned on for 100 msec, and the upper limit temperature (G) at that time is 8 ° C.
Suppose it was 5 ° C. In this case, the rate of increase = 50 (° C.
/ Sec). Also, the time from when the sheet is fed out to when it reaches the fixing roller 14 (B to C in FIG. 4).
Is 1 second, and a condition such that the fixing temperature E is 180 ° C. is set. Further, it is assumed that the held delay time K is 200 msec. In the first embodiment, the delay time K = 0 msec.
It takes 2 minutes to reach the fixing temperature E from when the heater is turned on.
It takes a second, but the fixing roller 1
4 (B to C in FIG. 4) is 1 second, and therefore, the time B at which the paper is fed out is 1 second from the time when the heater is turned on.
Seconds later. However, this delay time K = 200 mse
In the case of the condition c, the paper is fed out 800 msec after the preheating temperature. However, the time from when the heater is turned on to the fixing temperature E is not 2 seconds, but 1.8 seconds.
When this time is reached, turn off the heater. As described above, in the third embodiment, the on / off control of the heater in which the actual surface temperature of the fixing roller 14 is corrected in consideration of the response time (delay time K) of the thermistor 15 is performed. . Therefore, the effect of the response characteristic of the detection output of the thermistor 15 is removed, and the problem that the surface temperature of the fixing roller 14 excessively increases is prevented.

[0038]

According to the image recording apparatus of the first aspect, means for predicting the time from the preheating state to the temperature at which the image can be fixed is provided in advance, and the recording paper or the like is adjusted in accordance with the predicted recording start timing (time). Supplying recording media. Therefore, it is possible to control the temperature at the time of fixing to a predetermined value irrespective of the fluctuation of the power supply voltage, to prevent wasteful power consumption and to keep the recording medium such as recording paper at a constant temperature. The fixing operation can be performed, and high-quality recording can be obtained.

In the image recording apparatus according to the second aspect, the preheating temperature in the standby state is controlled so that the recording operation can be started within a predetermined time. Therefore, the recording operation can be started in a fixed time without being influenced by the fluctuation of the power supply voltage, and excessive heating is avoided, so that unnecessary power consumption is not generated.

In the image recording apparatus of the third aspect, the actual surface temperature of the fixing roller is controlled in consideration of the response time of the temperature detecting means such as a thermistor. Therefore, it is possible to prevent the surface temperature of the fixing roller from excessively increasing and maintain the recommended temperature, so that the service life is prolonged and the reliability of the apparatus is realized.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing an example of an embodiment of a main part configuration of a facsimile apparatus which is an example of an image recording apparatus of the present invention.

FIG. 2 is a schematic side view showing an example of a detailed configuration of a heat fixing unit provided in a recording unit 6 shown in FIG.

3 is a functional block diagram illustrating a configuration of a temperature detection system that detects a surface temperature of a fixing roller 14 illustrated in FIG.

FIG. 4 is a time chart illustrating an example of a relationship between a change state of a temperature of a fixing roller, a writing start time, and a sheet feeding timing in the image recording apparatus of the present invention.

FIG. 5 is a diagram illustrating a relationship between a temperature change in a standby state and a heater on in the heat fixing device.

FIG. 6 is a flowchart illustrating a flow of main processing when calculating a temperature rise rate of a fixing roller in the image recording apparatus of the present invention.

FIG. 7 is a time chart for explaining a delay in detection output of a thermistor detecting the surface temperature of the fixing roller 14;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main control part 2 Operation display part 3 NCU part 4 Modem 5 DCR part 6 Recording part 7 Reading part

Claims (3)

[Claims] 1. A heat fixing device for an image recording apparatus for forming an image such as a character or a figure by fusing toner to a recording medium such as recording paper by a fixing roller and a pressure roller, wherein the surface temperature of the fixing roller is controlled by A temperature detecting means such as a thermistor to be detected; and a standby state other than the recording operation, in which a temperature detected by the temperature detecting means and a heater ON / OFF control state are set in advance from a preheating state to a fixing possible temperature. An image recording apparatus, comprising: a time predicting unit for predicting the time of recording, and supplying a recording medium such as recording paper in accordance with the predicted recording start time. 2. A heat fixing device for an image recording apparatus for forming an image such as a character or a figure by fusing toner to a recording medium such as recording paper by a fixing roller and a pressure roller, wherein the surface temperature of the fixing roller A temperature detecting means such as a thermistor to be detected; and a standby state other than the recording operation, in which a temperature detected by the temperature detecting means and a heater ON / OFF control state are set in advance from a preheating state to a fixing possible temperature. An image recording apparatus, comprising: a time estimating unit for estimating a pre-heating time, wherein a preheating temperature in a standby state is controlled so that a recording operation can be started within the predetermined time. 3. A heat fixing device of an image recording apparatus for forming an image such as a character or a figure by fusing toner to a recording medium such as a recording paper by a fixing roller and a pressure roller, wherein the surface temperature of the fixing roller is adjusted. A temperature detecting means such as a thermistor to be detected; and a standby state other than the recording operation, in which a temperature detected by the temperature detecting means and a heater ON / OFF control state are set in advance from a preheating state to a fixing possible temperature. Time estimating means for estimating the time of the fixing roller.When the fixed time elapses after the estimated time elapses, the heater is controlled so that the surface temperature of the fixing roller does not rise to a prescribed temperature or more due to overshoot. An image recording apparatus, wherein the image recording apparatus is turned off.