JPH086434A - Heating device and image forming device - Google Patents

Abstract

PURPOSE:To stabilize image fixability in an image forming device provided with the heating device as an image heating/fixing device by making the control of a temperature stable and highly accurate. CONSTITUTION:In the heating device which is provided with a synchronizing timing detecting means 105 detecting the fact that the voltage of AC power 13 becomes a constant value or above or below, to periodically obtain synchronizing timing and obtains constant power in such a manner that the energization of a heating body 3 is ON or OFF in a specified time from the synchronizing timing, time that an AC power supply voltage is the constant value or below is counted and the timing of ON or OFF of the energization of the heating body 3 is changed according to the time. In other words, a synchronizing timing detecting means 105 and a current control means 11 are connected in series, so that the time from ON of the current control means 11 to the detection of the fact that a power supply voltage is the constant value or above by the synchronizing timing detecting means 105 is counted and the ON or OFF timing of the energization of the heating body 3 is changed in accordance with the time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device and an image forming apparatus provided with the heating device as an image heating and fixing device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a laser beam printer, a facsimile, a microfilm reader printer, an image display (display) device, a recording machine, etc., electrophotography, electrostatic recording, magnetic recording, etc. Directly on the surface of a recording material (electrofax sheet, electrostatic recording sheet, transfer material sheet, printing paper, etc.) as an image support using a toner composed of a heat-meltable resin by an appropriate image forming process means. Alternatively, as a heating device that heats and fixes an unfixed toner image (fixed image) corresponding to the target image information formed by the indirect (transfer) method as a permanently fixed image on the surface of the recording material carrying the image. The image heating and fixing device includes a heating roller that is maintained at a predetermined temperature, and a pressure roller that has an elastic layer and is in pressure contact with the heating roller. Thus heat roller type of heat while nipping and conveying the recording material is frequently used. In addition to this, various methods and configurations such as a flash heating method, an oven heating method, and a hot plate heating method are known.

Recently, in place of such a system, a film heating system heating device has been proposed and put into practical use (Japanese Patent Application Laid-Open No. 63-313182 and Japanese Patent Application Laid-Open No. 2-157).
No. 878 / JP-A-4-44075 / JP-A-4
-204980 gazette etc.).

In the film heating type heating device, the object to be heated is brought into contact with the object to be heated through the heat-resistant film and moved along with the film to move the heat of the object to be heated. It is of a system and a configuration in which it is transmitted to the object to be heated through, and can be utilized as an image heating fixing device. Further, not limited to the fixing device, it can be widely used as a means and device for heat-treating a material to be heated, such as a device that heats a recording material carrying an image to modify the surface property, a device that is supposedly attached.

Such a film heating type heating device is, compared to the conventional contact heating type heating roller type device ,. Since a low-heat-capacity heater can be used as the heater and a thin-film heater with a low heat-capacity can be used, it is possible to save power and shorten the wait time (quick start property). It is possible to suppress the temperature rise inside the machine such as the forming device. The image heating and fixing device is advantageous in that it can prevent offset because the fixing point and the separation point can be set separately, and that it can solve various drawbacks of other types of devices.

Temperature control is important for a heating device such as an image heating and fixing device. Particularly, in the case of the film heating type device, the temperature control is required to be more precise than the heat roller type such as phase control because the heat capacity of the heating element is small.

An example of the control circuit will be described with reference to FIG. 3. An AC power supply 13, a current control means 11 such as a triac, and a heating element 3 are connected in series, and a temperature detecting element (thermistor) arranged near the heating element 3 is provided. CPU based on temperature information shown in 5
10 controls the current control means 11 to keep the heating body temperature constant.

In order to send the synchronizing signal (point B) to the CPU 10, the synchronizing signal generating circuit 105 includes the heating element 3 and the current control means 11.
And are connected in parallel.

When the voltage at the point A is equal to or higher than the falling voltage of the Zener diode 107 which is the reference voltage generating means, the Zener diode 107 is short-circuited and the transistor 1
When 08 is on and the voltage is below the falling voltage, the Zener diode 107 is opened and the transistor 108 is turned off, and a pulse corresponding thereto is output to the photocoupler 10.
It is transmitted to the CPU 10 via 9 as a synchronization signal.

When the CPU 10 measures the synchronization of the AC power source from the synchronization signal and turns off the current control means 11 for a fixed time after the rise of the synchronization signal, a predetermined power is obtained.

[0011]

When the power supply voltage fluctuates, the voltage at the point A fluctuates and the rising and falling positions of the synchronizing signal move. Therefore, there arises a problem that the desired power and the actual power are deviated from each other and the temperature control becomes unstable.

Further, the position of the synchronizing signal also moves due to variations in the breakdown voltage of the Zener diode 107 between components, variations due to the ambient temperature, variations in the responsiveness of the photocoupler 109, and the like, causing the actual power generated to shift.

To briefly explain this, conventionally, the heater-off time T (heater-off time) required to obtain a predetermined energization ratio based on the measurement of half S of the power supply cycle from the synchronization signal
The on-time is set to S−T), and the predetermined electric power is obtained by repeatedly turning on and off the drive signal of the current control means T seconds after the rising of the synchronizing signal for each synchronization S. .

In this conventional method, when the rising and falling edges of the pulse move with respect to the power supply waveform due to fluctuations in the power supply voltage, variations in the Zener diode, etc., the actual output deviates from the desired energization ratio.

Particularly, in the vicinity of 100% and 0% of the output, the linearity is changed, so that the output may suddenly fluctuate, or the output may not change at all, thus making the temperature control unstable.

In view of this, the present invention has a synchronization timing detecting means for detecting the AC power supply voltage being above or below a certain value and periodically obtaining the synchronization timing, and the heating element is kept for a certain time from the synchronization timing. It is an object of the present invention to solve the above problems in a heating device that obtains a constant electric power by turning on or off the energization of the device for stabilizing the temperature control and increasing the accuracy. Another object of the present invention is to stabilize the fixing property of an image in an image forming apparatus provided with the heating device as an image heating and fixing device.

[0017]

The present invention is a heating device and an image forming apparatus characterized by the following configurations.

(1) A synchronization timing detecting means is provided for detecting that the AC power supply voltage is above or below a certain value to periodically obtain a synchronization timing, and the energization of the heating element is turned on or off for a certain period from the synchronization timing. In a heating device that obtains a constant electric power by turning off, the time when the AC power supply voltage is below a constant value is measured, and the timing of turning on or off the energization of the heating body is changed according to the time. Heating device.

(2) It has a synchronization timing detection means for detecting that the AC power supply voltage is above or below a certain value and periodically obtaining the synchronization timing, and energizes the heating element for a certain time from the synchronization timing. In a heating device that obtains a constant power by turning off, the synchronization timing detection means and the current control means are connected in series, and after turning on the current control means, the synchronization timing detection means causes the power supply voltage to be a certain value or more. A heating device that measures the time until it is detected that the timing of turning on or off the power supply to the heating body is changed according to the time.

(3) The signal to the current control means and the information from the means for detecting that the AC power supply voltage is above or below a certain value are monitored, and the AC power supply voltage is kept constant at the time when the current should be turned off. The second current control means stops the energization when it is detected that the value is equal to or more than the value (2).
The heating device according to.

(4) The heat of the heating member is transferred to the object to be heated by passing the object to be heated through a nip portion formed by the heating member and the pressure member. ) The heating device according to any one of 1).

(5) It has a heating element and a heat resistant film, one surface of which is in contact with the heating element and slides, and the other surface of which is in contact with the object to be heated.
The heating device according to any one of (1) to (3), wherein the heat-resistant film and the object to be heated move together on the heater to transfer the heat of the object to the object to be heated.

(6) The object to be heated is a recording material to be image-fixed, and an image heating fixing device for heating and fixing an unfixed image on the recording material (1) to (5). The heating device according to any one of 1.

(7) An image forming apparatus including the heating device according to any one of (1) to (5) as an image heating fixing device for heating and fixing an unfixed image on a recording material. .

(8) An image heating and fixing device in which the material to be heated is a recording material supporting an unfixed developer image to be image-fixed, and the unfixed developer image is heat-fixed on the recording material. The heating device according to any one of (4) to (7), characterized in that.

(9) An image characterized by including the heating device according to any one of (4) to (8) as an image heating fixing device for heating and fixing an unfixed developer image on a recording material. Forming equipment.

[0027]

That is, the present invention is designed to obtain a desired electric power by detecting the deviation of the synchronizing signal and correcting the deviation, and measures the time when the AC voltage is below a certain value, and measures it according to the time. By changing the timing at which the power is turned on or off, the fluctuation of the power supply ratio due to the fluctuation of the power supply voltage or the reference voltage is corrected and prevented, and stable temperature control can be obtained.

Further, the synchronization timing detection means and the current control means are connected in series, and the time from when the current control means is turned on to when the detection means detects that the power supply voltage exceeds a certain value is measured. By changing the timing of turning on or off the energization according to the time, it is possible to prevent the energization ratio from fluctuating due to the fluctuation of the response delay of the synchronous timing detecting means and the current control means, and to obtain stable temperature control. To be

[0029]

【Example】

<Embodiment 1> (FIGS. 1 to 5) FIG. 1 is a schematic configuration diagram of an example of a film heating type image heating and fixing device as a heating device of the present embodiment. FIG. 2 is a plan view of the heating element with the middle part omitted and partially cut away. This device is disclosed in JP-A-4-44075-44083 and JP-A-4-44075-44083.
This is a so-called tensionless type device disclosed in Japanese Unexamined Patent Publication Nos. 204980-204984. (1) Overall schematic configuration of the device This tensionless type device uses an endless belt-shaped or cylindrical heat-resistant film, and at least a part of the circumference of the film is always tension-free (a state in which no tension is applied). ) And the film is a device that is rotationally driven by the rotational driving force of the pressing member.

2 is an endless heat-resistant film,
It is externally fitted to a stay 1 which is a film guide member including a heating body 3 (heater). The inner peripheral length of the endless heat-resistant film 2 and the outer peripheral length of the stay 1 including the heating element 3 are larger than those of the film 2 by, for example, about 3 mm. Therefore, the peripheral length of the film 2 is loose with respect to the stay 1. Is fitted on.

The film 2 has a film thickness of 100 in order to reduce the heat capacity and improve the quick start property.
a monolayer film such as PTFE, PFA or FEP having a heat resistance of less than or equal to μm, preferably less than or equal to 50 μm and greater than or equal to 20 μm,
Or polyimide, polyamide imide, PEEK, PE
PTFE, PF on the outer peripheral surface of S, PPS, etc. films
A composite layer film coated with A, FEP or the like can be used. In this example, a polyimide film coated with PTFE on the outer peripheral surface was used.

The heating body 3 is an elongated substrate 31 of heat resistance, insulation, and good heat conductivity whose longitudinal direction is perpendicular to the transport direction a of the heat resistant film 2 or the recording material P as a material to be heated. A resistance heating element 32 formed along the length of the substrate at the center in the lateral direction of the substrate, a heat-resistant overcoat layer 34 for protecting the surface of the heating element on which the resistance heating element is formed, and a resistance heating element. Power supply electrodes 33 at both longitudinal ends of 32
33 (FIG. 2), a linear heating element having a low heat capacity as a whole, which is provided on the back surface side of the substrate and includes a temperature detecting element 5 such as a thermistor for detecting the temperature of the heating element.

The heating element 3 is fixedly arranged so that the surface side on which the resistance heating element 32 is formed and exposed is exposed downward and is held on the lower surface side of the stay 1 having rigidity and heat resistance.

The heating body substrate 31 is made of, for example, alumina or aluminum nitride and has a thickness of 1 mm, a width of 10 mm, and a length of 24.
It is 0 mm.

The resistance heating element 32 is, for example, Ag / Pd.
(Silver-palladium), RuO ₂ , Ta ₂ N, or other electric resistance material is formed by screen printing to have a thickness of about 10 μm and a width of 1 to 1.
It is formed by applying a 3 mm linear or strip shape.

The power supply electrodes 33, 33 are, for example, screen-printed pattern layers of Ag or the like.

The overcoat layer 34 is, for example, about 10
It is a heat-resistant glass layer having a thickness of μm.

Reference numeral 4 is a pressure roller as a film outer surface contact drive means for forming a pressure contact nip portion (fixing nip portion) N by sandwiching the film 2 with the heating body 3 and rotating the film 2.

The pressure roller 4 is composed of a core metal 4a and a heat-resistant rubber layer 4b having a good releasability such as silicon rubber, and the film 2 is sandwiched with a predetermined pressing force by bearing means and urging means (not shown). Are arranged in pressure contact with the surface of the heating element 3. Then, it is rotationally driven by the drive means M in the counterclockwise direction indicated by the arrow.

The rotational force acts on the film 2 by the frictional force between the pressure roller 4 and the outer surface of the film due to the rotational driving of the pressure roller 4.

The temperature of the heating element 3 is raised by heating the resistance heating element 32 over the entire length of the resistance heating element 32 by supplying power to the electrodes 33, 33 at both ends of the resistance heating element 32, and the temperature rise is detected by the temperature detecting element 5. . The output of the temperature detecting element 5 is A / D converted and fetched into the CPU 10, and based on the information, the AC voltage of the AC power source 13 which energizes the resistance heating element 32 by the triac 11 which is a current control means is heated by phase control or the like. The temperature of the heating element 3 is controlled by controlling the body-conducting power.

That is, when the detected temperature of the temperature detecting element 5 is lower than a predetermined set temperature, the heating body 3 is heated, and when the detected temperature is higher, the heating body 3 is cooled to control the energization to control the heating body. In No. 3, a constant temperature is adjusted during fixing.

Then, in a state where the temperature of the heating element 3 rises to a predetermined level and the rotational peripheral speed of the film 2 by the rotation of the pressure roller 4 is stabilized, the heating element 3 and the pressure roller are sandwiched with the film 2 interposed therebetween. The recording material P as an object to be image-fixed, which is to be subjected to image fixing, is introduced between the film 2 and the pressure roller 4 in the pressure contact nip portion N formed by the image forming portion (not shown) and the film 2 together with the film 2. The heat of the heating element 3 is applied to the recording material P through the film 2 by being nipped and conveyed to the recording material P by the pressure contact nip portion N, and the unfixed visible image (toner image) T on the recording material P becomes the recording material P. It is heated and fixed on the surface.
The recording material P passing through the pressure nip portion N is separated from the surface of the film 2 and conveyed. (2) Temperature Control System This embodiment has a synchronization timing detecting means for detecting that the AC power supply voltage is above or below a certain value to periodically obtain a synchronization timing as shown in FIG. In a heating device that obtains a constant electric power by turning on or off the energization of the heating body for a certain period of time, the time when the AC power supply voltage is a certain value or less is measured, and the energization of the heating body is turned on or Change the timing to turn off.

FIG. 4 shows a synchronizing signal waveform (point B) input to the CPU 10 in the control circuit of FIG. FIG. 5 shows an equivalent block diagram.

FIG. 4 shows that when the AC power supply voltage is high (135
V) and low (85V), and Zener diode 1
The case (V _H ) and the case (V _L ) of the falling voltage of 07 (hereinafter referred to as slice level) are high (V _L ) and low (V _L ), respectively.

When the voltage at the point A is lower than the slice level, the voltage of the synchronizing signal becomes 0V. The pulse widths h1 and h2 of 0 V are wider when the slice level is higher due to variations in the Zener diode 107 and the like, and narrower when the slice level is lower, and the rising and falling positions of the pulse are also moved.

Regarding the power supply voltage, when it is high, 0 V
Pulse width becomes narrower and becomes wider when it is low. When the power supply voltage is the lowest (85V) and the slice level is the highest (V
The sync signal waveform of _H ) is waveform Y, and the power supply voltage is the highest (1
The sync signal when the slice level is the lowest (V _L ) is displayed as the waveform X.

As described above, conventionally, the heater-off time T (heater-on time is S- A predetermined electric power is obtained by repeating the procedure of turning on the drive signal of the current control means and turning it off at the falling edge after T seconds from the rising edge of the synchronizing signal for each synchronization S.
In this conventional method, when the rise and fall of the pulse move with respect to the power supply waveform due to fluctuations in the power supply voltage, variations in the Zener diode, etc., the actual output deviates from the desired energization ratio. Especially, in the vicinity of 100% and 0% of the output, the linearity is changed so that the output may suddenly fluctuate, or the output may not be changed at all, which makes the temperature control unstable.

In this embodiment, 0V pulse width h1,
h2 is measured, and half of the value is measured for the heater-off time T
Then, the current control means drive signal is turned off from the pulse falling time Q1 and Q2. As a result, it is possible to obtain a predetermined energization ratio, that is, energized power, even if the power supply voltage or slice level changes.

In the present embodiment, a triac is used as the current control means 11, and the triac is driven by turning on the drive signal when the triac is desired to be turned on and turning off the drive signal when the synchronizing signal falls. Since the TRIAC has a switch characteristic, it continues to be energized until the AC power supply voltage becomes 0V even if the drive signal is turned off. As a result, stable temperature control can be obtained even near 100% output or 0% output.

Further, as the current control means 11, a transistor or the like having no switch characteristic may be used. In this case, the element is driven by turning off the time obtained by adding half of the 0V pulse width from the fall of the synchronizing signal. After that, the driving signal is turned on for a time T-S and turned off until the falling edge of the synchronizing pulse is repeated, or after the driving signal is turned on from the falling edge of the synchronizing signal to half the 0V pulse width, the time T Only after turning off the drive signal, turning on the drive signal until the fall of the synchronization signal may be repeated.

When the synchronization timing is taken from the rising edge instead of the falling edge, the drive signal is turned off for the time T-0V pulse width / 2 from the rising edge, turned on for the time S-T, and then turned off until the next rising edge. Good.

<Embodiment 2> (FIGS. 6 to 9) In this embodiment, as shown in FIG. 3, the synchronization timing for detecting that the AC power supply voltage is above or below a certain value to periodically obtain the synchronization timing. In a heating device that has a detection means and obtains a constant electric power by turning on or off the energization of the heating element for a predetermined time from the synchronization timing, the synchronization timing detection means and the current control means are connected in series,
Timing for measuring the time from when the current control means is turned on until it is detected by the synchronization timing detection means that the power supply voltage becomes a certain value or more, and the timing of turning on or off the energization of the heating body according to the time It is characterized by changing.

Although the power source voltage fluctuation and the slice level fluctuation of the Zener diode 107 can be corrected by the first embodiment, the photocoupler 1 in the control circuit of FIG.
There is a case where both the rising and falling edges of the synchronization signal are delayed due to the response delay such as 09. Further, it may take time before the current control means 11 operates even when the drive signal is turned on.

This embodiment detects and corrects these delays. That is, in the control circuit of FIG. 6, the current control means 11 and the synchronization timing detection means 105 are connected in series, and after the current control means drive signal (point F) is turned on, the CPU 10 outputs the input synchronization signal (point D). The delay time T _G until detecting that the current control means 11 is turned on can be detected. An equivalent block diagram is shown in FIG.

The sequence will be described with reference to FIG. First, the current control means 11 is turned on. Then the half-wave period S and 0
Measure the V pulse width T _H. Therefore, the falling edge of the sync signal pulse is detected twice or more (three times in the figure). After the final fall detection, the current control means 11 is turned off once and then turned on at the point that the power supply voltage is always higher than the slice level V _S of the Zener diode 107. This timing can be obtained by turning on at the time S / 2 after the fall of the synchronizing signal (point D).

Then, after the current control means drive signal (point F) is turned on, the CP is detected by the synchronization timing detection means 105.
The time T _G until U10 detects that the current control means 11 is turned on is measured.

After detection of T _G , description will be made with reference to FIG. When the power supply voltage becomes equal to or lower than the slice level V _S and the sync signal falls, the current control drive signal is turned off after a time T _U = T _H / 2-T _G.

Then, the time T _W = T from the fall of the synchronizing signal
_{After H} / 2- _TG + T (T is heater-off time), the current control means drive signal is turned on. Repeat this operation.

In this way, fluctuations in the power supply voltage, variations in slice level and temperature changes, response delays in the synchronization timing detection means, and response delays in the current control means 11 are all corrected to obtain a prescribed power supply ratio at all times. Stable temperature control can be performed.

<Embodiment 3> (FIG. 10) In this embodiment, the signal to the current control means and the information from the means for detecting that the AC power supply voltage is above or below a certain value are monitored to turn off the current. It is characterized in that the second current control means stops the energization when it is detected that the AC power supply voltage has become a certain value or more during the time to be set.

That is, the synchronization timing detecting means 105 in the control circuit of FIG. 6 of the above-described second embodiment can be used as the energizing current detecting means of the heating element 3. That is, as shown in FIG. 10, the second current control means 300 such as a relay is connected in series with the current control means 11.
And the current control means drive signal (point F) is off, when the energizing current is detected by the synchronization timing detection means 105, it is determined that the current control means 11 is broken and short-circuited, and the second current control means 300 is connected. Is turned off to prevent the heating element 3 from overheating.

<Fourth Embodiment> (FIG. 11) In this embodiment, a heating device of a heat roller type (image heating and fixing device) is similarly controlled.

In FIG. 11, a heat roller 301 is a tubular member made of a metal having good heat conductivity such as aluminum, and a heating element such as a halogen heater 305 is provided inside. A temperature detecting element 304 is attached to the heat roller 301, and the energization control system controls the energization of the heater 305 to keep the surface of the heat roller at a predetermined temperature.

The pressure roller 303 is formed on the core metal 303a in order to form a nip N that gives a sufficient amount of heat to heat and fix the toner T when the recording material P as a heated object is nipped and conveyed. Elastic layer 303b such as silicone rubber
Is formed.

When the halogen heater 305 generates heat, the surface temperature of the heat roller 301 rises. The temperature rise is detected by the temperature detecting element 304. The output of the temperature sensing element 304 is A
A / D conversion is performed, the data is taken into the CPU 10, and based on the information, the AC voltage of the AC power supply 13 for energizing the halogen heater 305 is controlled by phase control of the heater energization power by the triac which is the current control means 11, thereby heating the heat roller. Three
01 temperature control is performed.

That is, when the temperature detected by the temperature detecting element 304 is lower than a predetermined set temperature, the heat roller 301 is heated, and when it is high, the heat roller 301 is controlled so that the temperature is lowered. Is controlled at a constant temperature during fixing.

This apparatus uses the control circuit shown in FIG. 3 of the first embodiment and has a 0 V pulse width (h1, h2 in FIG. 4) of the synchronizing signal.
Is measured, and similarly to the first embodiment, the energization ratio is corrected based on the information so that it does not change due to power supply voltage fluctuations and slice level fluctuations.

The delay time (T _{G in} FIG. 8) from when the heater 3 is turned on to when it appears in the synchronization signal is measured by using the control circuit of FIG. On the basis of the information, the energization ratio is corrected so as not to change due to the response delay of the synchronizing signal generating circuit and the response delay of the current control means.

<Embodiment 5> (FIG. 12) FIGS. 12 (a), (b), and (c) show another example of the configuration of a film heating type heating device.

In (a), the heating element 3 and the driving roller 5 are used.
An endless belt-shaped heat-resistant film 2 is suspended and stretched between three members 1 and a driven roller (tension roller) 52, and the heat-resistant film 2 is rotationally driven by a drive roller 51. Reference numeral 53 denotes a pressure roller that is pressed against the heating body 3 with the film 2 sandwiched therebetween, and is driven to rotate as the film 2 rotates. Reference numeral 54 is a heater holder (heater holder).

In (b), the heating element 3 and the driving roller 5 are used.
Endless belt-shaped heat-resistant film 2 between two members 1
Is suspended and rotatably driven by the drive roller 51.

In the case of (c), the heat-resistant film 2 is not an endless belt-shaped one, but a long end film wound in a roll is used.
It is configured so as to run at a predetermined speed from the side to the winding shaft 56 side via the heating body 3.

<Embodiment 6> (FIG. 13) FIG. 13 is a schematic configuration of an example of an image forming apparatus in which a film heating type heating device according to the present invention as shown in the above-described embodiment is incorporated as an image heating and fixing device 60. Is shown. The image forming apparatus of this embodiment is a reciprocating platen type, a rotary drum type, a transfer type, and a process cartridge attaching / detaching type electrophotographic copying apparatus.

Reference numeral 61 is an apparatus casing, and 62 is a reciprocating type document placing table made of a transparent plate member such as a glass plate disposed on an upper surface plate 61a of the apparatus casing. In the drawing, they are reciprocally driven to the right a and the left a'at a predetermined speed.

Reference numeral G denotes an original, which is placed on the upper surface of the original placing table 62 according to a predetermined placing standard with the image surface side to be copied facing downward, and by placing the original pressure plate 62a on the original and pressing it. Set.

Reference numeral 61b denotes a slit opening serving as a document illuminating section which is opened on the surface of the upper surface plate 61a of the machine casing with a direction perpendicular to the reciprocating direction of the document placing table 62 (direction perpendicular to the paper surface) as a longitudinal direction.

Document G placed and set on the document table 62
The downward image surface passes through the position of the slit opening 61b sequentially from the right side to the left side in the forward movement process of the document placing table 62 to the right side a, and the lamp 6 is passed in the passing process.
The light L of the number 3 is applied to the slit opening 61b and the transparent document table 6
The light is reflected by the light source 2 and is illuminated and scanned, and the reflected light on the original surface of the illumination scanning light is imagewise exposed by the image element array 64 on the surface of the photosensitive drum 65.

The photosensitive drum 65 is, for example, a zinc oxide photosensitive layer.
A photosensitive layer such as an organic semiconductor photosensitive layer is coated and driven to rotate in a clockwise direction indicated by an arrow b around a central support shaft 65a at a predetermined peripheral speed. A uniform charging process is performed, and an imagewise exposure (slit exposure) of the document image is performed on the uniformly charged surface, so that an electrostatic latent image corresponding to the imagewise exposed document image is formed on the surface of the photosensitive drum 65. It is formed in sequence.

This electrostatic latent image is sequentially visualized by a developing device 67 with toner made of resin or the like which is softened and melted by heating, and the toner image as the visualized image is provided with a transfer discharge device 68 as a transfer portion. It moves to the part.

Reference numeral S denotes a cassette in which transfer material sheets P as recording materials are stacked and housed, the sheets in the cassette are fed out and fed one by one by the rotation of the feeding roller 70, and then the drum 65 is fed by the registration rollers 71. When the tip of the upper toner image forming portion reaches the portion of the transfer discharger 68, the tip of the transfer material sheet P is also transferred to the transfer discharger 68 and the photosensitive drum 65.
Then, the sheets are delivered in a synchronized manner with the timing reached so that they reach exactly the position between and.

Then, the toner image on the side of the photosensitive drum 65 is sequentially transferred by the transfer discharger 68 onto the surface of the fed sheet.

The sheet to which the toner image has been transferred at the transfer portion is sequentially separated from the surface of the photosensitive drum 65 by a separating means (not shown), and is guided to the fixing device 60 by the conveying device 72 to carry the unfixed toner. When the image T is heated and fixed,
An image formed product (copy) is discharged onto a discharge tray 74 outside the apparatus through a discharge roller 73.

The surface of the photosensitive drum 65 after the image transfer is subjected to removal of adhering contaminants such as transfer residual toner by the cleaning device 69, and is repeatedly used for image formation.

The PC is a process cartridge which is attached / detached to / from the cartridge attaching / detaching portion 77 in the apparatus main body 75. In the case of this example, the photosensitive drum 65 as an image carrier and the charger 6 are provided.
6, process unit 67, developing unit 67, and cleaning device 69 are included and can be attached to and detached from the apparatus main body 61 collectively.

[0086]

As described above, it is detected that the AC power supply voltage is above or below a certain value to periodically obtain the synchronization timing, and the energization of the heating element is turned on or off for a certain period from the synchronization timing. In a heating device that obtains a constant power by doing the following: 1) By measuring the time when the AC voltage is below a constant value and changing the timing of turning on or off the energization according to the time, the power supply voltage or the reference The stable temperature control can be obtained by correcting and preventing the fluctuation of the energized power ratio due to the voltage fluctuation.

2) Further, the synchronization timing detection means and the current control means are connected in series, and the time from when the current control means is turned on to when the detection means detects that the power supply voltage exceeds a certain value is determined. By measuring the timing and changing the timing of turning on or off the energization according to the time, it is possible to prevent the energization ratio from fluctuating due to the fluctuation of the response delay of the synchronization timing detection means and the current control means, and to stabilize the temperature control. Is obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a film heating type heating device (image heating and fixing device) according to a first embodiment.

[Fig. 2] Plan view of the heating element with the middle part omitted and partially cut away

FIG. 3 is a circuit diagram for controlling the energization of the heating element.

FIG. 4 is a relational diagram (waveform diagram) of AC power supply voltage, synchronization signal, and heater energization.

5 is an equivalent block diagram of the circuit of FIG.

FIG. 6 is a circuit diagram of an energization control for a heating body of the device according to the second embodiment.

7 is an equivalent block diagram of the circuit of FIG.

FIG. 8: Current control means drive signal, heater energization voltage, and C
PU input relationship diagram

FIG. 9 is a relationship diagram (waveform diagram) of heater energization, CPU input, and current control means drive signal.

FIG. 10 is a circuit diagram of an energization control for a heating body of the device according to the third embodiment.

FIG. 11 is a schematic view of an apparatus of Example 4 (heat roller type image heating and fixing apparatus).

12 (a), (b), and (c) are schematic views of another example of the configuration of the film heating type heating device.

FIG. 13 is a schematic diagram of an example of an image forming apparatus.

[Explanation of symbols] 1 stay 2 heat resistant film 3 heating body 4 pressure roller 5 temperature detecting element 10 CPU 11 current control means 13 AC power supply T toner P recording material N nip 105 synchronization timing detection means 300 second current control means 301 Heat Roller 303 Pressure Roller 304 Temperature Detector 305 Halogen Heater 401 Detecting Means 402 402 Reference Voltage Generating Means 403 Comparing Means

Claims (9)

[Claims] 1. A synchronization timing detection means for detecting that the AC power supply voltage is above or below a certain value to periodically obtain a synchronization timing, and energizes or deenergizes the heating element for a certain period from the synchronization timing. In the heating device to obtain a constant power by doing, characterized in that the time when the AC power supply voltage is below a certain value is measured, and the timing of turning on or off the energization of the heating body is changed according to the time. Heating device. 2. A synchronous timing detecting means for detecting that the AC power supply voltage is above or below a certain value to periodically obtain a synchronizing timing, and turning on or off energization to the heating body for a certain period from the synchronizing timing. In the heating device that obtains a constant power by doing so, the synchronization timing detection means and the current control means are connected in series, and the power supply voltage becomes a certain value or more by the synchronization timing detection means after turning on the current control means. A heating device that measures the time until a thing is detected and changes the timing of turning on or off the energization of the heating body according to the time. 3. The signal to the current control means and the information from the means for detecting that the AC power supply voltage is above or below a certain value, and the AC power supply voltage is at a certain value at the time when the current should be turned off. The heating device according to claim 2, wherein when the above is detected, the second current control means stops the energization. 4. The heat of the heating member is transferred to the object to be heated by passing the object to be heated through a nip portion formed by the heating member and the pressing member. The heating device according to any one of claims. 5. A heating element, one surface of which is in sliding contact with the heating element,
The other surface has a heat-resistant film in contact with the object to be heated, and the heat-resistant film and the object to be heated move together on the object to transfer the heat of the object to the object to be heated. The heating device according to any one of claims 1 to 3. 6. The image heating fixing device according to claim 1, wherein the object to be heated is a recording material on which an image is to be fixed, and the image heating fixing device heats and fixes an unfixed image on the recording material. The heating device according to claim 1. 7. An image forming apparatus, comprising the heating device according to claim 1 as an image heating fixing device for heating and fixing an unfixed image on a recording material. 8. An image heating fixing device for heating a material to be recorded, which supports an unfixed developer image to be image-fixed, and heat-fixes the unfixed developer image to the recording material. The heating device according to any one of claims 4 to 7, wherein: 9. An image forming apparatus comprising the heating device according to any one of claims 4 to 8 as an image heating fixing device for heating and fixing an unfixed developer image on a recording material. .