JP3466770B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a copying machine or a facsimile, and more particularly to an image forming apparatus such as an electrophotographic recording apparatus or an electrostatic recording apparatus having a heat fixing device.

[0002]

2. Description of the Related Art The outline of image forming operation in a conventional general electrophotographic laser printer is as follows.
A laser beam modulated according to image data is irradiated onto the image carrier uniformly charged by a charging unit such as a charging roller, and a desired electrostatic latent image is obtained. This latent image is subjected to reversal development at a developing portion by a developing device such as a developing device arranged so as to face the latent image and is visualized as a toner image. This toner image is electrostatically transferred by a transfer means such as a transfer roller to a sheet-shaped recording material (transfer paper, recording paper, etc.) that is fed and conveyed from a cassette or the like, and then is transferred to a heat fixing device or the like. The fixing means permanently fixes the recording material at a predetermined fixing temperature.

As the heating and fixing device, a heat roller type is often used because of its safety, high thermal efficiency, good fixing property and adaptability for speeding up. This heat roller type fixing device has a heat source such as a halogen heater inside and is composed of a fixing roller pair consisting of a heating roller rotating in a fixed direction and a pressure roller rotating in pressure contact with the heating roller. Then, the toner image is heated and pressed through the recording material carrying the toner image on the roller pair to fix the toner image on the recording material.

The surface temperature of the heating roller is detected by a temperature detecting member, and the heat source is adjusted via a control circuit in response to a signal from the temperature detecting member so that the surface temperature of the heating roller becomes a predetermined print temperature (fixing temperature). Temperature).
This is because if the surface temperature of the heating roller is too low, fixing failure of the toner image occurs, and if it is too high, offset transfer of the toner image to the heating roller (referred to as high temperature offset) occurs. Controlling to a predetermined constant value is extremely important.

Conventionally, in the above-described laser printer, the surface temperature of the heating roller is set at a standby temperature (standby temperature) in a ready state in which a start request signal of an image forming operation from a host such as a personal computer can be accepted at any time during standby. When printing after receiving the image data from the host, the controller of the laser printer confirms the ready state, then transmits a print signal, switches the standby temperature to a predetermined print temperature, and outputs the desired temperature. I'm getting a print image.

On the other hand, after the power is turned on, a ready signal indicating that the image forming (printing) operation is possible is made when the surface temperature of the heating roller reaches a predetermined ready temperature (ready temperature) by the heating source. I am emitting. These states are shown by the curve A in FIG. In the figure, the fixing roller pair is rotated from the room temperature T _R until the ready temperature T _r is reached in order to uniformly heat the pressure roller to improve the fixing property and reduce the fixing unevenness. In addition, the ready temperature T _r
And the standby temperature T _S are set to be the same, and the print temperature T _p is set higher than the standby temperature T _S. The standby temperature T _S is set to a temperature at which the print source can reach the print temperature T _p by the heating source before the recording material starts being fed after the print signal is received and the recording material enters the heat fixing device. Has been done. By setting in this way, it is devised to reduce the power consumption during standby.

[0007]

However, in the conventional example as described above, the ready temperature T _r (standby temperature T _S ) is fixed to a predetermined constant value. Variations in voltage and electric power of the heater, which is a heating source, also affect the print temperature T _p, and there is a drawback in that the above-described fixing failure and high temperature offset occur.

For example, when the upper limit voltage of the power supply voltage is input, particularly in the case of so-called morning print, which is a print immediately after the power is turned on, the overshoot of the heating body surface temperature becomes considerably large (see FIG. 8). (See curve B),
High temperature offset is likely to occur. On the other hand, when the lower limit voltage of the guaranteed range of the power supply voltage is input to the heater in a low temperature environment, it becomes difficult to increase the standby temperature to the print temperature (see the broken line C in FIG. 8), and the fixing failure occurs. Will occur.

Further, in order to reduce the cost of the apparatus, when the model of each destination, for example, the heat fixing apparatus of 100V machine for domestic use and 120V machine for North America is made common, The problem of becomes more prominent. In this regard, an example of a halogen heater, which is a commonly used tungsten incandescent light bulb, is shown. The rate of change in power consumption (W / W ₀ ) with respect to the rate of change in input voltage (V / V ₀ ) of the halogen heater approximately has the following relationship.

[0010]

[Number 1] _{W / W 0 = (V /} V 0) 1.54 ... (1) Consequently, the specified range of the supply voltage is 10% ±, in the case where entered the 90V and 132V to a heater, from the above equation to 90V On the other hand, when 132V is input, the power consumption is about 1.8 times, and it can be seen that it is very difficult to make the heating and fixing device of 100V and 120V common.

The present invention solves the problems of the prior art as described above, and even when the ambient environmental temperature or the input voltage to the heater changes, a desired print image can be formed without causing fixing failure or high temperature offset. 100V at the same time you get
It is an object of the present invention to provide an image forming apparatus in which a heating and fixing device for a 120V machine and a 240V machine for Europe and a 240V machine for Europe are also commonly used.

[0012]

In order to achieve the above object, the present invention according to claim 1 is directed to an image forming means for forming a toner image on a recording material, and heating the toner image formed on the recording material. A fixing unit having a heating body for fixing and a temperature detecting unit for detecting the temperature of the heating unit; and a control unit for controlling the temperature of the heating unit based on the temperature detected by the temperature detecting unit. Te, based on the power-on the temperature rise value per unit time of the heating body after emits a ready signal indicating that it is possible to accept the start request signal of the image forming operation and a control means for setting a ready temperature , The above
The control means starts the image forming operation from the host after the power is turned on.
There is a start request, and image formation starts immediately after the ready signal is output.
And a determination means for determining whether or not
It characterized the this <br/> to set different ready temperatures depending on the determination result of.

[0013]

In order to achieve the above object, the present invention according to claim 2 has an image forming means for forming a toner image on a recording material, and a heating body for heating and fixing the toner image formed on the recording material. And a fixing means having a temperature detection means for detecting the temperature of the heating body, and a control means for controlling the temperature of the heating body on the basis of the temperature detected by the temperature detection means. on the basis of the temperature rise value per unit time of the heating body, ready temperature emits a ready signal indicating that it is possible to accept the start request signal of the image forming operation, or a control means for setting a standby temperature is ready The temperature detected by the heating element after the power is turned on.
When the temperature of the heating element starts to rotate,
In addition, the temperature rise per unit time before rotating the heating element
The value of the specific temperature is variably set based on the value .

[0015]

[0016]

[0017]

In the first embodiment of the present invention, the heating element after the power is turned on.
Image forming operation based on the temperature rise value per unit time of
Ready signal indicating that the start request signal of
Set the ready temperature to issue a signal, but at that time, turn on the power
After that, image formation is started without maintaining the standby temperature.
Depending on the result of the judgment, different lady
Set the temperature. Request from the host to start image forming operation
Yes, does image formation start immediately after the ready signal is output?
Determine whether or not. This shuts off the power to the heating element.
Instead, it is controlled toward the target temperature as it is, so it starts up.
Increases speed and suppresses overshoot
However, it is possible to prevent the occurrence of high temperature offset.
It

In the second embodiment of the present invention, the power is turned on.
After that, when the detected temperature T _t of the heating element reaches a specific temperature,
When the rotary drive is started,
Based on the temperature rise value β per unit time, the above specific temperature
The value T _{t of} is set variably. This allows, for example, β
The value is too large to reach the range where overshoot is unacceptable.
If it is estimated that the temperature will reach T _t ,
By increasing the rotation time of the wear roller pair,
Can be controlled to suppress shoots, and what is this?
On the contrary, the value of β is small and the high temperature
If you don't have to worry about fusing, raise the temperature of T _t
By shortening the rotation time of the fixing roller pair,
It can be controlled to shorten the dead time.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings.

Reference Example FIGS. 1 to 3 show a reference example on which the present invention is based . Figure 1
Shows a schematic sectional structure of a laser printer (laser beam printer) which is an image forming apparatus of a reference example which is a premise of the present invention . The laser printer 910 of this reference example is a host 9 such as a personal computer or a workstation.
00, and when the image data from the host 900 is received, it is expanded by the controller 921 into bitmap data. The image signal expanded into the bitmap data is the video interface 9
22 and the DC controller 923, the image is sent to the engine section of the laser printer 910, and the engine section forms a desired image by raster scanning while modulating the laser beam 913 by the scanner 924 based on the image signal.

At this time, the controller 921 and the engine portion of the laser printer 910 are connected to the video interface 92.
The following communication is carried out via 2. First, the engine section confirms the recording material size based on a signal from the controller 921, and when the paper can be fed and the printer can be operated, a ready signal is sent to the controller 92.
Send to 1.

Next, the controller 921 confirms that the ready signal from the engine unit is transmitted, and transmits a print signal, which is a paper feed command, to the engine unit.

Upon receipt of this print signal, the engine portion immediately feeds the recording material P from the recording material storage portion such as the cassette 920 by the paper feeding roller 915, and the registration roller 916.
Carry to. At the same time, in the heat fixing device 919, the halogen heater 9 disposed inside the heating roller 901 is used.
02 is controlled by the DC controller 923 to switch the surface temperature of the heating roller 901 from the standby temperature to the print temperature. This surface temperature is detected by a temperature detecting member 905 such as a thermistor (NTC), and the DC controller 92
A controlled temperature is controlled by 3.

Here, the temperature detecting circuit will be briefly described. A fixed resistor is connected in series to the temperature detecting member 905 which is in contact with the surface of the heating roller 901, and the voltage applied to these fixed resistors is connected in series. The partial pressure value is set to the heating roller 9
The temperature is detected by converting it into a voltage signal corresponding to the surface temperature of 01.

The recording material P is temporarily stopped by the registration roller 916, and after waiting for the rise of a scanner motor (not shown) in the engine section and the completion of preparatory rotation (so-called pre-rotation) such as potential stabilization of the photosensitive drum 911, It waits until the printer section becomes ready for image writing. Then, after exchanging a predetermined signal between the engine section and the controller 921, an image signal is sent to the engine section, and the recording material P is conveyed from the registration roller 916 to the transfer section.

Next, image formation in the laser printer section will be described. The photosensitive drum 911 having a photosensitive layer such as an organic semiconductor (OPC) is uniformly charged by a charging unit such as a charging roller 912, and then irradiated with the laser beam 913 modulated according to the above-described image signal to obtain a desired one. An electrostatic latent image is obtained. This electrostatic latent image has a developing device 9 having toner.
14 is developed and visualized as a toner image.
This toner image is electrostatically transferred to a recording material P by a transfer unit such as a transfer roller 917 in a transfer portion, and then the recording material P is conveyed to a heat fixing device 919 so that the toner image is permanently fixed and the paper discharge portion. The recording material P is discharged from the sheet, and a desired print image is obtained.

The toner left untransferred on the photosensitive drum 911 is cleaned by a cleaner 918 having a cleaning blade or the like, and the same image forming process as described above is repeated. Incidentally, the developing device 914, the charging roller 912, the photosensitive drum 9 of the image forming unit described above.
The cartridge 11 and the cleaner 918 may be integrally configured to be a cartridge that is detachable from the main body.

Next, the basic control of the heat fixing device 919 in the engine portion of this reference example will be described with reference to the flowchart of FIG. First, when the engine is powered on (S100), the halogen heater 902 is energized to raise the heating roller surface temperature T toward the ready temperature. In the meantime, in this reference example, while the fixing roller pair 901 and 904 are rotated for the purpose of improving fixing property and eliminating fixing unevenness, the output from the above-mentioned temperature detection circuit is detected, for example, every 5 ms, and the unit The rising degree α of the temperature rise per unit time is calculated (S101). Since it is difficult to detect an accurate temperature in the vicinity of the room temperature T _{R due} to the performance of the temperature detection circuit, the value α [° C./sec] is actually determined by the rising degree in the vicinity of the ready temperature Tr 2 having a high temperature detection accuracy. It will be.

Here, the time from when the print signal is received until the recording material P actually enters the heat fixing device 919 is
In the apparatus of the reference example, it is 10 seconds, for example. The print temperature T _p of the main heat fixing device 919 is set to 160 ° C.
Suppose If it is assumed that the value of the degree of rise α that has been determined at that time is α = 2 ° C./sec, the standby temperature T _S during standby is set to at least 140 ° C. or more,
Since an appropriate print image will be obtained, it is decided in this reference example that T _S = 145 ° C. (S10).
2).

The ready temperature T _r for issuing the ready signal may be set to 145 ° C., but is determined in consideration of the temperature corresponding to the rising degree α and the overshoot amount stored in advance in the device. . In this reference example, _Tr
= 140 ° C. is determined (S103).

Regarding the relationship between the degree of rising and the amount of overshoot stored in the apparatus in advance, the energization time to the heater 902 up to the ready temperature T _r is counted by a timer (not shown), and a predetermined time is set. If it is shorter, it is judged that there is less overshoot, and the ready temperature T
Needless to say, it is necessary to consider that _r is set to the same temperature as the standby temperature T _S.

After this, the surface temperature T of the heating roller 901 is
However, the same operation as described above is repeated until the T _r temperature determined at that time is reached (S104), and when the T _r temperature is reached, a ready signal is transmitted (S105). At this point, the print signal from the controller 921 is ready to be received.

If the print signal from the controller 921 due to the start request of the image forming operation from the external host 900 is not received by this time (S106), the surface temperature T of the heating roller 901 is directed to the standby temperature T _S. Control (S107), and a standby state for waiting a print signal is set.

Here, when a print signal is received from the controller 921 (S106), preparations such as paper feeding and pre-rotation are immediately started, and at the same time, the target temperature of the surface of the heating roller 901 is set to a preset print temperature T _p. The recording material P is temporarily stopped by the registration roller 916 (S108).

Next, the start-up of the scanner and the photosensitive drum 9
If the preparatory processing (so-called pre-rotation) performed before the normal image writing operation such as the potential stabilization of 11 is completed (S10)
9) After transmitting and receiving a predetermined signal, the registration roller 916 is rotated to convey the recording material to the transfer section (S1).
10).

Subsequently, when the recording material carrying the unfixed toner image is conveyed to the heating and fixing device 919 and the fixing operation is completed (S111), the heating roller surface temperature controlled to the print temperature T _p is set to standby. The temperature is controlled to T _S (S107), and the standby state for waiting for the print signal is resumed (S106).

The manner of controlling the surface temperature of the heating roller in the above-described reference example is shown in FIG. 3 and will be described step by step. In the figure, it has reached room temperature T from the state of _R heat source power supply to the (halogen heater) 902 is started, the ready temperature rise of alpha = 2 ° C. / sec T _r. In the figure, since the print signal has not been transmitted up to this point, the power supply to the heating source 902 is once interrupted at the ready temperature _Tr . By controlling in this way, overshoot is suppressed. Next, the standby temperature T _S
The print signal is received and controlled to the print temperature T _{p after} being controlled to. Here, it can be seen that the temperature at which the first recording material P enters the heat fixing device 919 is at a temperature at which it can be sufficiently fixed. When this fixing is completed, the standby temperature T _S
Controlled by.

In this reference example, the halogen heater 902 which is a heating source consumes 600 W of electric power, and a rise of α = 2 ° C./sec is described. However, even if this rise speed changes, Since the ready temperature T _r and the standby temperature T _S are determined accordingly, a desired print image can be obtained without causing fixing failure even when the ambient environment or the input voltage to the heater changes.

[0039] will be described with reference to the first embodiment (first embodiment) the present invention in FIGS. The description of the common points with the above-mentioned reference example is omitted. In Figure 4 of the first embodiment, an example in which printing from the host 900 side to reach the room temperature T _R to ready temperature T _r is required. Further, the halogen heater 902 consumes 800 W of electric power so that the rising speed is higher than that in the reference example.

As shown in the reference example, the ready temperature Tr
When the value α of rising degree α = 3 ° C./second is determined in the vicinity, if the standby temperature T _S is set to 130 ° C. or higher, fixing failure does not occur. Therefore, T _S = 135 ° C. is set here.

Next, regarding the calculation of the ready temperature, the points different from the reference example will be described with reference to the flowchart of FIG. As shown in the flow chart of FIG.
After the calculation of the standby temperature T _S , it is confirmed whether or not there is a request to start the image forming operation from the host 900 side (S12).
0).

If there is no such request, the ready temperature T _r is calculated and determined by the same method as in the reference example (S103).
However, in the case of the present embodiment in which there is a request to start the image forming operation, the value of the ready temperature T _r is calculated and then corrected and confirmed (S121). That is, in addition to the relationship between the pre-stored degree of rise and the amount of overshoot described in the reference example, the temperature of _Tr is considered in consideration of the energization time to the ready temperature, the fixability in that case, and the high temperature offset. Is corrected. In this device, T _r =
Determined to be 130 ° C.

When T _r = 130 ° C. is reached, a ready signal is transmitted (S105) and a print signal is received (S106). However, in this embodiment, unlike the reference example, a halogen heater as a heating source is used. The power is not supplied to 902, and the temperature is controlled as it is toward the target temperature Tp (S108).

In this image forming apparatus, the recording material P enters the heating and fixing device 919 10 seconds after the print signal is received, and at the rising speed of α = 3 ° C./sec, the recording material P is calculated. At that point, it will be just 160 ° C. However, particularly when a high input voltage is applied to the normal rated voltage, an overshoot occurs due to the heat quantity of the heating roller 901, the thermal time constant of the NTC (902), etc., and the actual heating roller surface The temperature is higher than the printing temperature T _p = 160 ° C. This state is indicated by ΔT in FIG.

In this embodiment, the pair of fixing rollers 901 and 9 are used.
When the recording material enters the nip portion 04 (see the arrow portion of the first sheet in FIG. 4), the heat of the heating roller 901 is abruptly taken by the recording material to suppress the overshoot. That is, the ready temperature T _r for issuing the ready signal
It is possible to suppress the overshoot and prevent the occurrence of high temperature offset by correcting the value to a low level at which the fixing property can be secured and nipping and conveying the recording material to the nip portion at an appropriate timing.

[0046] will be described with reference to (a second embodiment) FIGS. 6 and 7 a second embodiment of the present invention. Note that description of common points with the reference example is omitted. In FIG. 6 of the second embodiment, in order to simplify the explanation,
T _r = T _S. In the apparatus of this embodiment, the room temperature T
_The fixing roller pair 901 and 904 are not rotated until the temperature reaches a preset temperature T _t from the time when _R reaches the ready temperature _Tr, and the fixing roller from T _t to _Tr is not rotated. The pairs 901 and 904 are rotated. FIG. 6 shows how the surface temperature of the heating roller of the image forming apparatus is raised at this time. _{T R} ~T _t between and _T t ~T _r
The value of the rising degree of the temperature rise per unit time between
[° C./sec] and γ [° C./sec]. It will be shown below that the present invention can be applied to an apparatus adopting the control as in the present embodiment.

The control procedure of the apparatus of this embodiment will be described with reference to the flowchart of FIG. Participation as the rising value
Although β is determined instead of α described in the consideration example (S130), the difference from the reference example is that the value of γ is calculated before calculating the standby temperature T _S (S131). To calculate γ, study the relationship between β and γ when conditions such as the ambient environment and the voltage within the guaranteed range of the power supply voltage are shaken in advance, and set the device so that γ can be calculated from β according to a predetermined decision. Just remember it.

[0048] For the next standby temperature _{T S,} participation
Like the considered example, it can be determined from γ is calculated (S103). Since the subsequent steps are similar to those of the reference example, description thereof will be omitted.

On the other hand, the method of determining the temperature of T _t is fixed to a certain temperature in this embodiment, but β
Is large and it is estimated that the overshoot reaches an unacceptable range, the temperature of T _t is lowered and the rotation time of the fixing roller pair 901 and 904 is lengthened to suppress the overshoot. You may control to. On the contrary, if β is small and there is no concern about high temperature offset due to overshoot,
The weight time may be controlled to be shortened by increasing the temperature of T _t and shortening the rotation time of the fixing roller pair 901 and 904.

Further, in order to reduce the wait time, the fixing roller pair 901 and 904 are not rotated from the room temperature T _R until the ready temperature T _r is reached, that is, image formation without so-called multiple rotation before fixing. It is needless to say that it is also applicable to the control of the apparatus.

From the first embodiment of the present invention described above
In the second embodiment, the heating roller surface temperature T at power-on
In the above, the case where T ≦ T _r is satisfied has been described. However, in the case where T> T _r is satisfied, the control when the jam processing is performed immediately after printing will be described below.

If the power is not turned off during the jam processing,
After the jam processing, the ready signal is issued and the target temperature is controlled toward the standby temperature T _S until then, and the standby state is set. Further, since it is assumed that the power is turned off and the jam processing is performed, it is needless to say that the standby temperature T _S used until then must be held by a storage means such as a memory.

[0053]

As described above, according to the present invention,
After the power is turned on, there is a request from the host to start the image forming operation.
Whether the image formation starts immediately after the ready signal is output.
Whether the ready temperature differs depending on the judgment result
Is set so that the power to the heating element is not interrupted.
Since the temperature is controlled as it is toward the target temperature,
The speed increases and the overshoot is suppressed,
It is possible to prevent the occurrence of high temperature offset, and it is possible to obtain a desired print image without causing defective fixing or high temperature offset.

Further, according to the present invention , heating is performed after the power is turned on.
When the detected temperature T _{t of the} body reaches a specific temperature, the heating body is driven to rotate.
Unit time before starting the rotation of the heating element
Based on the hit temperature rise value β, the value T _{t of the} specific temperature
There since to be variably set, the value of β is large, Oh
It is estimated that the overshoot will reach an unacceptable range.
If the fixing roller pair is lowered, the temperature of T _t is lowered.
Overshoot is suppressed by increasing the rotation time.
Can be controlled so that the value of β is
Small, worrying about high temperature offset due to overshoot
If there is not , raise the temperature of T _t and set the fixing roller pair.
The weight time is shortened by shortening the rotation time of
It can be controlled to shrink . Further, according to the present invention, for the same reason, it is possible to provide an image forming apparatus in which the heat fixing device of 100V machine and 120V machine can be shared, and further the 240V machine for Europe can be shared.

Further, according to the present invention, for the same reason, the heat fixing device of 100V machine and 120V machine is made common,
Furthermore, it is possible to provide an image forming apparatus that can be commonly used for 240V machines for Europe.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a laser printer of a reference example which is a premise of the present invention.

FIG. 2 is a flowchart showing a control procedure of a reference example which is a premise of the present invention.

FIG. 3 is a characteristic diagram showing a change in surface temperature of a heating roller in a device of a reference example which is a premise of the present invention.

FIG. 4 is a characteristic diagram showing changes in the heating roller surface temperature in the apparatus according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing a control procedure of the first embodiment of the present invention.

FIG. 6 is a characteristic diagram showing changes in the heating roller surface temperature in the apparatus of the second embodiment of the present invention.

FIG. 7 is a flowchart showing the control procedure of the second embodiment of the present invention.

FIG. 8 is a characteristic diagram showing a change in surface temperature of a heating roller in a conventional device.

[Explanation of symbols]

900 Host 901 Heating roller 902 Heating source (halogen heater) 904 Pressure roller 905 Temperature detecting member 910 Laser printer 911 Photosensitive drum 914 Developing device 915 Paper feeding roller 916 Registration roller 917 Transfer roller 919 Heat fixing device 920 Cassette 921 Controller 923 DC controller T _r Ready temperature T _S Standby temperature T _p Printing temperature α, β, γ Heating roller surface temperature rising speed

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-6-194995 (JP, A) JP-A-4-288561 (JP, A) JP-A-7-36353 (JP, A) JP-A-2- 181775 (JP, A) JP-A-2-181774 (JP, A) JP-A-3-175510 (JP, A) JP-A-2-27384 (JP, A) JP-A-63-253977 (JP, A) JP-A-59-136768 (JP, A) JP-A-62-266571 (JP, A) JP-A-3-200185 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/00 303 G03G 15/20 109 G03G 21/00 370-512 G05D 23/19

Claims (2)

(57) [Claims] 1. A temperature detecting device, comprising: an image forming unit for forming a toner image on a recording material; and a heating body for heating and fixing the toner image formed on the recording material, and detecting the temperature of the heating body. Fixing means having means, and control means for controlling the temperature of the heating body based on the temperature detected by the temperature detecting means, based on a temperature rise value per unit time of the heating body after power is turned on. , Yes and a control means for setting a ready temperature which emits a ready signal indicating that it is possible to accept the start request signal of the image forming operation
Then, the control means controls the image forming operation from the host after the power is turned on.
There is a request to start, and image formation is started immediately after the ready signal is output.
It has a judgment means for judging whether or not to start
Set different ready temperature according to the judgment result by means.
Image forming apparatus characterized by that. 2. A temperature detection device, comprising: an image forming unit for forming a toner image on a recording material; and a heating body for heating and fixing the toner image formed on the recording material, and detecting the temperature of the heating body. Fixing means having means, and control means for controlling the temperature of the heating body based on the temperature detected by the temperature detecting means, based on a temperature rise value per unit time of the heating body after power is turned on. , and a control means for setting a standby temperature is ready temperature or ready state, emits a ready signal indicating that it is possible to accept the start request signal of the image forming operation, after power-on, the detection temperature of the heating body Becomes a certain temperature
When the rotational drive of the heating body is started,
Based on the temperature rise value per unit time before rotational drive,
An image forming apparatus characterized in that a value of a specific temperature is variably set .