JPH11288193A - Fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain power consumption of an entire device and to restrain cost increase by stopping energizing a 1st heating body but energizing a 2nd heating body when recording material does not pass the press-contact part of fixing film. SOLUTION: When the temperature of the 1st heating body 102 attains temperature required for fixing, the recording material is carried to the fixing device 101 and the fixing is performed. In such a case, the temperature of the 1st heating body 102 is detected by a temperature sensor 5 and the 1st heating body 102 is controlled to specified temperature by a control circuit 4 based on the detected temperature. In such a case, high power is required in an instant, so that image forming operation is started, and heating driving the 2nd heating body 110 from a 2nd heating body driving circuit 3 is stopped when driving the 1st heating body 102 is started. When the recording material does not pass a fixing position, that is, fixing operation is not performed, the temperature of the 1st heating body 102 can be lowered, whereby power for generating the quantity of heat equivalent to lowering the temperature is supplied to the 2nd heating body 110.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a fixing device for heating and fixing an image formed on a recording material onto the recording material, and an image forming apparatus provided with the fixing device.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a fixing device 101. In FIG. 7, reference numeral 102 denotes a low-heat-capacity linear heating element (hereinafter, abbreviated as a first heating element) fixedly supported by the apparatus. , Referred to as a resistor) 102b, and the resistor 102b is energized from both ends in the longitudinal direction.

A fixing film 103 is in contact with the first heating element 102, and the fixing film 103
The drive roller 104, the driven roller 105, and the tension roller 106 allow the roller to move in the arrow direction without wrinkling while obtaining a predetermined tension. Although the fixing film 103 in the illustrated example has an endless shape, the fixing film sent out from the supply roller may be brought into contact with the heating element 102 and then wound up by the winding roller.

A recording material 107 is conveyed along a guide table 108 with the movement of the fixing film 103, and is a pressure contact portion N between a pressure roller 109 as a pressure member and a first heating element 102. When the recording material passes through the fixing position, the toner image T on the recording material is heated and softened and melted.
07.

In order to perform this fixing, the first heating element 102 must be heated from 180 ° C. to 200 ° C. in a few seconds, and a very large amount of electric power is required. Of the recording material 107, the thickness of the recording material 107, and the like. That is, the larger the number of sheets fixed per unit time, and the shorter the time from the start of the operation of the apparatus to the first recording material to the fixing position, the first heating element 102
Requires a large amount of heat and a large amount of electric power.

On the other hand, the pressure roller 109 is at an ambient temperature, and particularly in a cold atmosphere, the heating of the first heating element 102 is started, and the rotation operation of the fixing film 103 and the pressure roller 109 is started. When this is performed, the low-temperature portion passes through the heat-generating portion of the first heating element 102, so that the heat generated by the first heat-generating element 102 is lost one after another, and the temperature required for fixing is quickly reached. Can not.

Therefore, a second heating element 110 is provided in the pressure roller 109 to heat the pressure roller 109 itself.
Can be kept high, and the first heating element 102 can be quickly raised to the fixing temperature at the start of fixing.

When the temperature of the first heating member 102 reaches a temperature required for fixing, the recording material 107 is transported to the fixing device 101 and fixing is performed. At this time, the first heating element 102
Is detected by a temperature sensor 111, and the temperature of the pressure roller 109 is detected by a temperature sensor 112, and is controlled to a predetermined temperature by a control circuit described later based on the detected temperature. The temperature sensors 111 and 112 use a thermistor or the like.

In this case, the first heating element 102 has a power capacity of about 800 W to 1000 W and the second heating element 11
In the case of 0, the power capacity is about 200 W to 400 W, and when these and other power supply loads are added, a power capacity of one thousand and several hundred watts is instantaneously required.

FIG. 8 is a schematic diagram showing an image forming apparatus to which the fixing device 101 is applied. 8, reference numeral 111 denotes a platen glass on which a document (not shown) is placed; 112, a pressure plate for pressing the document; 113, a platen glass 11;
Illumination lamps for illuminating the original placed on 1; 114, a photosensitive drum rotatably supported by the apparatus main body 115 in the direction of the arrow; 116, a developing device arranged in proximity to the photosensitive drum 114; 117, a photosensitive drum 114; A registration roller 119 is provided in a conveyance path 118 that conveys the recording material 107 to the recording material 107 at a timing, and a transfer device 119 transfers a visible image from the photosensitive drum 114 to the recording material 107.
A cleaning device 121 for removing the transfer leakage developing material remaining on 14, a charging device 121 for uniformly charging the surface of the photosensitive drum 114, and a recording material detection sensor 122 provided on the upstream side of the register roller 7, for example, A photo interrupter is used.

Next, the operation will be described. Photosensitive drum 1
Reference numeral 14 denotes an original illumination lamp 1 which is driven to rotate in the direction of the arrow.
13. First and second heating elements 102, 1 of fixing device 101
10 is energized. The surface of the rotating photosensitive drum 114 is uniformly charged by the charger 121.

The charged photosensitive drum surface has an illumination lamp 1
The document image illuminated at 13 is scanned and exposed to form an electrostatic latent image. This electrostatic latent image is developed by the developing unit 116 to be visualized. As this developing method, a jumping developing method, a two-component developing method, an FEED developing method, or the like is used.
Image exposure and reversal development can be used in combination.

The visualized toner image is transferred to a transfer unit 119.
Is transferred from the photosensitive drum 114 onto the recording material 107 conveyed at a predetermined timing. At this time, the recording material 107 is sandwiched between the photosensitive drum 114 and the transfer device 120 with a constant pressing force, is conveyed to the fixing device 101, and the toner image T is fixed on the recording material 107 as a permanent image in the fixing device 101. You.

On the other hand, the residual toner remaining on the photosensitive drum 114 is removed from the surface of the photosensitive drum 114 by the cleaning device 120, and the photosensitive drum 114 is used for the next image formation.

[0015]

However, during the fixing operation of the conventional fixing device, the fixed heating device and the second heating member in the pressing member are provided with the fixing device. The applied image forming apparatus simultaneously energizes the first and second heating elements and a load having a large power consumption, such as a document reading illumination lamp, so that the total power consumption increases. As a result, it is necessary to increase the rating of the components of the fixing device or the image forming apparatus, and there is a problem that the cost is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a fixing device in which the power consumption of the entire device is suppressed and the cost is reduced, and an image forming apparatus provided with the fixing device. With the goal.

[0017]

According to the present invention, there is provided a fixing device and an image forming apparatus having the following constitution.

(1) A first heating element fixed and supported, a pressure member for pressing the fixing film against the first heating element, and a second heating element built in the pressure member are provided. The fixing device further includes a control unit that stops the power supply to the first heating body and supplies power to the second heating body when the recording material does not pass through the pressure contact portion of the fixing film. apparatus.

(2) The control of energization and non-energization of the first heating element and the second heating element is performed at least every half cycle of the AC power supply.
The fixing device as described in the above.

(3) a recording material detecting means disposed upstream of the fixing position where the fixing film is pressed against the first heating element and on the recording material conveying path to detect a leading end and a trailing end of the recording material; Counting means for counting the time during which the recording material has passed through the fixing position based on the detection value of the detection means; and a detection value of the recording material detection means and a count value of the counting means. The fixing device according to (1), further comprising control means for controlling energization of the first heating element and the second heating element.

(4) An image forming means, and the fixing means according to any one of claims 1 to 3, wherein the image is fixed on a recording material on which an unfixed image is formed by the image forming means. During the image forming operation, when the recording material has not passed through the fixing unit, the control temperature value of the first heating element is lower than the control temperature value when the recording material is passing. An image forming apparatus comprising: a control unit for setting and increasing the amount of electric power supplied to a second heating element.

(5) An image forming means including a document reading illumination lamp, and the image is fixed on a recording material on which an unfixed image is formed by the image forming means. 2. The fixing device according to claim 1, wherein the recording material passes a control temperature value of the first heating element when the recording material does not pass through the fixing device during an image forming operation. Control means for setting the temperature to be lower than the control temperature value at the time and increasing the amount of power supplied to the second heating element, and the control means supplies power to the second heating element when the original reading illumination lamp is turned on. The image forming apparatus is characterized in that when stopped, the second heating element is energized when the illumination lamp for reading a document is turned off.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

Embodiment 1 FIG. 1 is a control block diagram of the fixing device according to the first embodiment. Since the hardware configuration of the fixing device is the same as that of the conventional device shown in FIG. 7, the illustration is omitted, and the components in the description are shown in FIG.
Is assigned. FIG. 1 shows a commercial power supply (hereinafter, referred to as a power supply), which includes a first heating element 102 and a second heating element 110.
Is connected. 2 is a first heating element drive circuit that controls the energization of the first heating element 102, 3 is a second heating element drive circuit that controls the energization of the second heating element 110,
4 is a control circuit having a memory 4a, 5 is the first heating element 1
02 is a first temperature sensor for detecting the temperature of 02, 6 is a second temperature sensor for detecting the temperature of the second heating element 110, 7 is a third temperature sensor for detecting the temperature around the device, and 8 is a control circuit. 6 is a motor drive circuit that receives a control signal from the motor 6 and operates the drive motor 9 that drives the drive roller 104.

Next, the operation will be described. When the power of the fixing device is turned on, a drive signal is sent from the control circuit 4 to the second heating element driving circuit 3, and the energization of the second heating element 110 is started. It is kept around 100 ° C. The amount of heat generated by the second heating element 110 is set based on the heat capacity of the pressure roller 109 and the heat capacity of other members constituting the surroundings. Further, the temperature of the second heating element 110, that is, the surface temperature of the
The detection signal is supplied to the control circuit 4, and the control circuit 4 controls the second heating element 110 via the second heating element driving circuit 3 so that the surface temperature of the pressure roller 109 becomes a predetermined temperature. To control the energization.

Here, when the fixing operation is started based on the detection signal of the conveyance state of the recording material 107, the control circuit 4 outputs a control signal to the motor drive circuit 8, and the motor drive circuit 8 9 is operated to move the fixing film 103 via the driving roller 104. At the same time, a trigger signal is sent to the first heating element drive circuit 2 to start driving the first heating element 102 for heating.

When the temperature of the first heating member 102 reaches a temperature required for fixing, the recording material 107 is moved to the fixing device 10.
1 and is fixed. At this time, the temperature of the first heating element 102 is detected by the temperature sensor 5 and is controlled to a predetermined temperature by the control circuit 5 based on the detected temperature.

In this case, the first heating element 102 has a current carrying capacity of about 800 W to 1000 W, and the second heating element 11
In the case of 0, assuming that the current carrying capacity is about 200 W to 400 W, the sum of these and other power supply loads, etc., instantaneously requires an electric power of several hundred watts. Therefore, when the image forming operation is started and the driving of the first heating element 102 is started, the second heating element 110 from the second heating element driving circuit 3 is used.
The heating drive to is stopped. Then, when the recording material 107 does not pass through the fixing position, that is, when the fixing operation is not performed, the temperature of the first heating body 102 can be reduced, so that the amount of heat required to reduce the temperature is generated. Can be supplied to the second heating element 110.

The energizing circuits of the first heating element driving circuit 2 for the first heating element 102 and the second heating element driving circuit 3 for the second heating element 110 are energized and de-energized every cycle of the AC power supply 1. Is determined in advance according to the energization pattern stored in the memory. This energization pattern is divided into several types of patterns corresponding to the temperature value detected by the temperature sensor 6 of the first heating element 102, and according to the amount of heat to be driven by the detected temperature as shown in FIG. The control circuit 4 controls the selected pattern to perform the heating drive.

Therefore, during the image forming operation,
When the first heating element 102 and the second heating element 110 are simultaneously heated and driven, the power capacity becomes large. Therefore, when the first heating element 102 is not energized, the second heating element 110 is energized. That's all I need to do.

As described above, the energizing pattern of the first heating element 102 is a combination pattern for each input AC cycle. The temperature of the body 110 is detected, and if the temperature is lower than a predetermined value, control is performed so as to energize the second heating body 110. FIG. 3 shows an energization pattern of the first heating element 102 and the second heating element 110 at this time. In the illustrated example, control is performed using a combination pattern for each AC cycle, but a combination may be performed for at least half a cycle. 2 and 3, the hatched portions indicate the energized state, and the others indicate the non-energized state.

FIG. 4 is a flowchart for explaining the above-described energization control. When the temperature of the first heating element 102 is detected by the temperature sensor 5 (step ST1), the energization pattern (FIG. 3) of the first heating element is stored in the memory 4 based on the detected temperature.
a (step ST2). Next, it is determined whether or not the first heating element 102 is an energization (ON) cycle (step ST3). If YES, the first heating element 102 is energized via the first heating element driving circuit 2 (step ST3).
4).

On the other hand, if the determination result is NO, the first heating element 102 is turned off (OFF) (step S
T5) The temperature sensor 6 detects whether the temperature of the second heating element 110 is equal to or lower than a predetermined value (step ST6). If NO, the process returns to the return. If YES, the process proceeds through the second heating element driving circuit 3. Then, power is supplied to the second heating element 110 in the same power supply pattern as that of the first heating element 102 (step ST7).

Embodiment 2 FIG. 5 is a control block diagram of an image forming apparatus according to Embodiment 2 to which the control block of the fixing device of the present invention shown in FIG. 1 is applied. The hardware configuration of the image forming apparatus is the same as that of the conventional apparatus shown in FIG. In FIG. 5, reference numeral 10 denotes a lamp driving circuit for controlling energization of the illumination lamp 113, and reference numeral 11 denotes a motor drive which receives a control signal from the control circuit 4 and operates a driving motor 11 for driving the driving roller 104, the photosensitive drum 114 and the like. Other components are the same as the components shown in FIG. 1 except for the circuit, and therefore, the same portions are denoted by the same reference numerals and the description thereof will not be repeated.

Next, the operation will be described with reference to the flowchart of FIG. When the power of the image forming apparatus is turned on, the image forming apparatus enters a standby state, a drive signal is sent from the control circuit 4 to the second heating element driving circuit 3, and the energization of the second heating element 110 is started. The surface temperature of the pressure roller 109 is kept at around 100 ° C. This second heating element 11
The heat value of 0 is set based on the heat capacity of the pressure roller 109 and the heat capacity of other members constituting the periphery. Further, the surface temperature of the pressure roller 109 is detected by the temperature sensor 6, and this detection signal is supplied to the control circuit 4. The control circuit 4 controls the surface temperature of the pressure roller 109 to a predetermined temperature by the control circuit 4. The energization of the second heating element 110 is controlled via the heating element driving circuit 3.

Here, when the image forming operation is started, the control circuit 4 outputs a control signal to the motor drive circuit 11, which activates the motor 12 through the drive roller 104. To move the fixing film 103. At the same time, a trigger signal is sent to the first heating element drive circuit 2 to start driving the first heating element 102 for heating.

Next, when the temperature of the first heating member 102 reaches a temperature required for fixing, the recording material 107 is moved to the fixing device 101.
And is fixed. At this time, the temperature of the first heating element 102 is detected by the temperature sensor 5 and is controlled to a predetermined temperature by the control circuit 4 based on the detected temperature.

Therefore, when the image forming operation is started, the driving of the first heating element 102 is started, and the lighting of the illumination lamp 113 is controlled by the lamp driving circuit 10, the heating element from the second heating element driving circuit 3 is controlled. The heating drive to 110 is stopped. When the reading scan ends and the illumination lamp 113 is turned off by the lamp driving circuit 4, the heating drive from the second heating body driving circuit 3 to the heating body 110 is started.

In the case where the image forming operation is a continuous operation, when the reading scan of the illumination lamp 113 is completed, the illumination lamp 113 is turned off when moving to the home position. 110 is driven for heating.

Further, when the fixing operation of the recording material 107 is not performed by the fixing device 101, the first heating element 1
Since the temperature of No. 02 can be lowered, the amount of heat for lowering the temperature can be supplied to the second heating element 110.

During the above-described image forming operation, the recording material 107 passes through the recording material detection sensor 122, stops at the nip of the registration roller 117 for a predetermined time, and is conveyed to the photosensitive drum 114 at a predetermined timing. These operations are controlled by the control circuit 4, and the control circuit 4 controls the recording material 107 by the recording material detection sensor 122 while the recording material 107 is being conveyed by the registration rollers 117.
Is detected, the length information of the recording material is counted, the time from when the registration roller 117 is operated to the time when the leading end of the recording material 107 reaches the fixing device 101, and when the recording material 107 passes through the fixing device 101. Count the time to end.

The control circuit 4 determines, based on the counted time, that the recording material 107 has passed the fixing position and the fixing operation is being performed, and the first heating element 102 is required for fixing. The heating is controlled at a predetermined temperature value, and the power supply to the second heating element 110 is stopped by the second heating element driving circuit 3.
When the recording material 107 has passed the fixing position and the fixing operation has been completed, the control temperature value of the first heating element 102 is set and controlled to a temperature value lower than a predetermined value at the time of the fixing operation. The second heating element 110 is operated by the second heating element driving circuit 3.
To start heating.

Therefore, during the image forming operation, even while the illumination lamp 113 is on, the first heating element 10
2 can be heated.

When the image forming operation is completed, the trigger signal sent from the control circuit 4 to the first heating element driving circuit 2 is stopped, and the heating drive to the first heating element 109 is stopped. Further, the fixing film 103 and the photosensitive drum 114
The drive of the motor drive circuit 11 of the motor 12, which is a drive unit for moving the motor, is stopped, and the process returns to the standby state. In this state, the driving of the second heating element 110 via the second heating element driving circuit 3 is started.

FIG. 6 is a flowchart for explaining the energization control of the first heating element 102 and the second heating element 110 during the above operation. After the first heating element 102 is driven for heating (step ST11), the illumination is performed. It is determined whether or not the lamp 113 is turned on (step ST12), and in the case of NO, the second heater 110 is driven to heat (step ST1).
5). If the above determination is YES, the recording material 107
Determines whether the sheet is passing through the fixing device 101 (step ST1).
3) In the case of NO, a return is reached, and in the case of YES, the control temperature value of the first heating element 102 is reduced (step ST1).
4), drive the second heating element 110 by heating (step S)
Y5).

As described above, in the image forming operation, when the fixing operation of the recording material 107 is not performed by the fixing device 101, the driving control is performed so that the first heating member 102 is heated. The device can be configured so that large power is not supplied to the device.

[0047]

As described above, according to the present invention, a first heating member fixed and supported, a pressing member for pressing a fixing film against the first heating member, and a built-in pressure member When the recording material does not pass through the pressure contact portion of the fixing film, the power supply to the first heating body is stopped and the power supply to the second heating body is performed. With such a configuration, it is possible to speed up the start-up of the apparatus, stably perform fixing, and suppress the power consumption of the entire apparatus. In addition, since the energization / de-energization control for the first heating element and the second heating element is configured to be performed at least every half cycle of the AC power supply, fine temperature control can be performed and stable fixing can be performed. There is an effect that can be performed.

A recording material detecting means disposed upstream of a fixing position at which the fixing film is pressed against the first heating member to detect a leading end and a trailing end of the recording material; A counting unit that counts a time during which the recording material has passed the fixing position based on a detection value of the unit, a detection value of the recording material detection unit, and a count value of the counting unit, With the configuration including the control means for controlling the energization of the first heating element and the second heating element, it is possible to accurately determine whether or not the recording material passes through the fixing position. Thus, there is an effect that energization control for the first heating element and the second heating element can be reliably performed.

An image forming means including an illumination lamp for reading an original, and any one of the above (1) to (3) for fixing the image on a recording material on which an unfixed image is formed by the image forming means. And a control unit, when the recording material does not pass through the fixing unit during an image forming operation, the control unit sets the control temperature value of the first heating body to the recording material. Is set to be lower than the control temperature value at the time of passing, and the amount of electric power supplied to the second heating element is increased, so that the fixing can be stably performed and the apparatus during the image forming operation It is possible to suppress the entire power consumption. As a result, the maximum power of the entire apparatus can be reduced, and the ratings of components and the like used in the apparatus can be suppressed, so that an image forming apparatus with low cost can be obtained.

Further, the control means stops supplying power to the second heating element when the original reading illumination lamp is turned on, and supplies electric power to the second heating element when the original reading illumination lamp is turned off. Since the configuration is such that the power consumption is reduced, the power consumption of the entire apparatus during the image forming operation can be easily suppressed.

[Brief description of the drawings]

FIG. 1 is a control block diagram of a fixing device according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation according to the first embodiment of the present invention.

FIG. 3 is an energization pattern diagram for a heating element.

FIG. 4 is a diagram showing a state of energization of a first heating element and a second heating element.

FIG. 5 is a control block diagram of an image forming apparatus according to a second embodiment of the present invention.

FIG. 6 is a flowchart illustrating an operation according to the second embodiment of the present invention.

FIG. 7 is a configuration diagram illustrating a fixing device.

FIG. 8 is a configuration diagram illustrating an image forming apparatus.

[Explanation of symbols]

4 control circuit (control means, counting means), 101 fixing means, 102 first heating element, 103 fixing film, 1
07 recording material, 113 illumination lamp, 122 recording material detection sensor (recording material detection means).

Claims (5)

[Claims] 1. A fixing device comprising: a first heating member fixed and supported; a pressing member for pressing a fixing film against the first heating member; and a second heating member built in the pressing member. A fixing unit for stopping the power supply to the first heating body and supplying power to the second heating body when the recording material does not pass through the pressure contact portion of the fixing film. . 2. The fixing device according to claim 1, wherein control of energization and non-energization of the first heating element and the second heating element is performed at least every half cycle of an AC power supply. 3. A recording material detecting means which is disposed upstream of a fixing position where a fixing film is pressed against a first heating member and which is located upstream of a recording material conveyance path, and detects a front end and a rear end of the recording material, and the recording material detection. A counting unit that counts a time during which the recording material has passed the fixing position based on a detection value of the unit, a detection value of the recording material detection unit, and a count value of the counting unit, The fixing device according to claim 1, further comprising a control unit configured to control energization of the first heating element and the second heating element. 4. An image forming means, and the fixing means according to claim 1, wherein the image is fixed on a recording material on which an unfixed image is formed by the image forming means. During the image forming operation, when the recording material does not pass through the fixing unit, the control temperature value of the first heating element is set lower than the control temperature value when the recording material passes. An image forming apparatus comprising a control unit for increasing the amount of electric power supplied to the second heating element. 5. An image forming unit including an illumination lamp for reading a document, and the image is fixed on a recording material on which an unfixed image has been formed by the image forming unit. The fixing means according to the item, and during the image forming operation, when the recording material is not passing through the fixing means, the control temperature value of the first heating element, when the recording material is passing Control means for setting the temperature lower than the control temperature value and increasing the amount of power supplied to the second heating element, the control means stopping the power supply to the second heating element when the document reading illumination lamp is turned on. When the illumination lamp for reading the original is turned off, the second heating element is energized.