JP3121918B2 - 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 having a fixing device composed of a heating roller and a pressure roller, and more particularly, to an image forming apparatus capable of passing long paper of a fixed size or more. The present invention relates to an image forming apparatus.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus having a fixing device including a heating roller and a pressure roller, a toner image transferred to a transfer sheet is semi-fused by the heat of the heating roller in the fixing device, and the transfer sheet is heated. Infiltrate inside and fix.

On the other hand, in recent image forming apparatuses, a long transfer paper (hereinafter, referred to as a long paper) has been demanded by a user to use a paper having a size larger than a standard size such as A4 size or B5 size as a transfer paper. ) Is provided.

[0004]

However, according to the conventional image forming apparatus, long paper of a fixed size or more (for example, a paper having a width of A4 and a length twice as large as A3) is passed. In this case, since the heat taken from the heating roller of the fixing device by passing the paper increases in proportion to the length of the long paper, the temperature of the heating roller decreases, and the toner cannot be reliably fixed. there were. In particular, when continuous paper is continuously fed, there is a high possibility that defective toner fixation will occur.

[0005] The present invention has been made in view of the above, and an object of the present invention is to reliably fix toner even when long paper is passed.

[0006]

[0007]

[0008]

[0009]

[0010]

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a fixing device in which a heater is incorporated in both a heating roller and a pressure roller, and the rotation of the roller compared to a fixed size sheet. Determining means for determining the passage of long paper, which is a sheet having a long length in the direction; and controlling means for turning on a heater of the pressure roller when the determining means determines that long paper is to be passed. , And an image forming apparatus having the same.

According to another aspect of the present invention, there is provided a fixing device comprising a heating roller and a pressure roller.
An image forming apparatus having a long paper of a fixed size or more
Means for determining whether or not the paper has passed
The first and the fixing device always heater is ON, normally the second fixing device is a heater is OFF state, the-size <br/> by means determines the sheet passing of long paper, said there is provided a control means for the heater to the ON state of the second fixing device, an image forming apparatus having a.

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[Action] The image forming apparatus of the present invention (claim 1), when fed a long paper turns on the heater of the pressure roller, both from the long paper heat between the heating roller and the pressure roller give.

An image forming apparatus according to the present invention (claim 2 )
When the long paper is passed, the heater of the second fixing device is turned on, and the fixing is performed by both the first fixing device and the second fixing device.

[0020]

[Embodiment] In the above configuration, the image forming apparatus of the present invention is used in [Embodiment 1], [Embodiment 2], [Embodiment 3], [Embodiment 4], [Embodiment 5], [Embodiment 6]. ] And [Embodiment 7] will be described in detail with reference to the drawings.

FIG. 1A is a control block diagram of an image forming apparatus according to a first embodiment, and includes heaters 101 and 102 for fixing processing and a temperature detector for detecting the temperatures of the heaters 101 and 102. Thermistors 103 and 104, a CPU 105 for controlling lighting of the heaters, an AC power supply 106 for supplying power to the heaters 101 and 102, and ON / OFF of power supply to the heaters 101 and 102 based on a control signal from the CPU 105. SSR 107 (switch) for switching. SW1 indicates a switch for designating long paper passing when long paper other than the standard size is passed, and is provided on an operation panel (not shown) of the image forming apparatus. .

FIG. 1B shows the structure of the fixing device 108. As shown in the figure, the fixing device 108 includes a heating roller 109 having two heaters 101 and 102 therein, and a pressure roller 11 for nipping the transfer paper together with the heating roller 109.
0.

The operation of the above configuration will be described. Normally, only the heater 101 is turned on to heat the heating roller 109 when a fixed-size transfer sheet is passed, but the switch SW1 is pressed when a long sheet other than the fixed-size sheet is passed. As a result, the CPU 105 recognizes the passage of long paper, turns on the heater 102 in addition to the heater 101, and heats the heating roller 109. Therefore, by turning on the two heaters, the heating roller 109 is printed on the long paper.
Even if some heat is removed, the heating roller 109 can be quickly heated, and the toner can be reliably fixed.

[Second Embodiment] In the image forming apparatus of the second embodiment, when long paper is recognized, a fan motor for rotating a fan is stopped to prevent a rise in temperature inside the image forming apparatus. Make the inside of the device heated,
In that, paper is passed.

FIG. 2 is a control block diagram of the image forming apparatus according to the second embodiment, which controls a fan motor 201 for driving a fan for preventing a rise in temperature, a driver 202 for rotating the fan motor 201, and a driver 202 for controlling the driver 202. CP to do
U203. SW1 is a switch for designating long paper passing.

In the above configuration, the CPU 203 normally rotates the fan motor 201 via the driver 202 when a fixed-size transfer sheet is passed. Thereby, the heat inside the image forming apparatus is exhausted, and the temperature rise is prevented. On the other hand, when passing long papers other than the standard size, pressing the switch SW1 causes the CPU 2 to release the paper.
03 recognizes the passing of long paper, and stops the fan motor 201 via the driver 202. Therefore, heat is not exhausted from the inside of the image forming apparatus, and the inside of the apparatus is heated. Therefore, when the internal temperature of the apparatus rises while the rotation of the fan motor 201 is stopped, the temperature of the entire apparatus rises, and a certain amount of heat is given to the long paper even before the fixing process. ) Can be prevented from unnecessarily removing heat, and the toner can be reliably fixed.

In the second embodiment, the fan motor 201
Is stopped. For example, as shown by a broken line in FIG. 2, the current supplied to the fan motor 201 is suppressed by using a driver 204 having a resistor R attached to reduce the output current. The rotation speed of the motor 201 may be reduced.

[Embodiment 3] In the image forming apparatus of Embodiment 3, when long paper is continuously fed, the paper feed timing is controlled later than usual, and the temperature of the heating roller is sufficiently raised. The fixing is performed in a state where the fixing is performed.

FIG. 3 is a control block diagram of the image forming apparatus according to the third embodiment. A paper feed roller 402 (details will be described later) for feeding transfer paper from a paper feed unit 401 (see FIG. 4) not shown. To drive the clutch 301 and the clutch 3
01, and a CPU 303 that controls the driver 302. In addition, SW1
Indicates a switch for designating long paper passing.

FIG. 4 is a schematic configuration diagram of an image forming apparatus 400 according to the third embodiment. As shown in the figure, inside the image forming apparatus 400, a paper feed unit 401 for feeding a transfer paper such as a fixed size and a long paper, a paper feed roller 402 for feeding the transfer paper from the paper feed unit 401, and a fixing device 403. Is arranged.

In the above configuration, when passing long papers other than the standard size, pressing the switch SW1 causes the CPU 303 to recognize the passage of the long papers.
If the continuous feeding of the long paper is continued, the drive timing of the clutch 301 via the driver 302 is delayed from the normal timing and controlled by the timing. As a result, the clutch 301
Turns ON later than the normal timing, rotates the paper feed roller 402, and starts the transfer of the transfer paper. In other words, the long paper is passed at a large interval. Therefore, even if the heat amount of the heating roller (not shown) is deprived once by passing the long paper, the continuous temperature of the long paper has sufficient margin to recover the fixing temperature when the continuous paper is continuously passed. By passing the paper, the toner can be reliably fixed at a sufficient temperature.

[Embodiment 4] In the image forming apparatus of Embodiment 4, when long paper is passed, fixing is performed in a state where the temperature of the heating roller is sufficiently raised by controlling the entire driving speed to be slow. Is what you do.

FIG. 5 is a control block diagram of the image forming apparatus according to the fourth embodiment. The main motor 501 of the driving system, the polygon motor 502 of the optical system, and the driver 50 for driving the main motor 501 and the polygon motor 502 respectively.
3, 504, programmable counters 505 and 506 for changing the frequency division ratio of the reference clock 508, and a CPU 507 for controlling the whole. Reference numeral 508 denotes a reference clock, and SW1 denotes a switch for designating long-sheet passing.

In the above configuration, when passing long paper other than the standard size, the CPU 507 recognizes the passage of long paper by pressing the switch SW1. CPU
Reference numeral 507 changes the frequency division ratio of the reference clock 508 via the programmable counters 505 and 506 to reduce the rotation speed of the main motor 501 and polygon motor 502. As a result, the overall driving speed is reduced, and the speed of passing long paper is also reduced.

In general, the conditions necessary for fixing the toner are three factors: temperature, time, and pressure. In the fourth embodiment, the paper passing speed of long paper is reduced (that is, the paper passing time is lengthened). )
Therefore, even if the temperature of the heating roller is slightly
It takes a long time to fix and fix the toner.

[Fifth Embodiment] In the image forming apparatus of the fifth embodiment, when a long sheet is passed, the sheet conveyance drive after the fixing device is controlled to be slower than the sheet conveyance drive immediately before the fixing device. The fixing is performed with a longer contact time between the heating roller and the long paper.

FIG. 6 is a control block diagram of the image forming apparatus according to the fifth embodiment. The image forming apparatus according to the fifth embodiment includes a drive system motor 6 that drives the sheet to be transported immediately before the fixing device 609.
01, and a drive system motor 602 for driving paper conveyance after the fixing device. In the figure, 603, 6
04 denotes drivers 603 and 604 for driving the drive system motors 601 and 602, 605 and 606 denote programmable counters for changing the frequency division ratio of the reference clock 608, and 607 denotes a CPU for controlling the whole.
SW1 indicates a switch for designating long paper passing.

In the above configuration, when passing long papers other than the standard size, the CPU 607 recognizes the passage of the long papers by pressing the switch SW1. CPU
Reference numeral 607 changes the frequency division ratio of the reference clock 608 via the programmable counter 606 to reduce the rotation speed of the drive system motor 602 after the fixing device. As a result, the sheet conveyance speed before the fixing device 609 does not change, and the sheet conveyance speed after the fixing device 609 decreases. Therefore, even if the temperature of the heating roller is slightly lowered, the toner can be fixed over a long time and the toner can be surely fixed even if the temperature of the heating roller is slightly lowered by lowering the feeding speed of the long paper in the fixing device 609.

Since the sheet conveying speed before the fixing device 609 does not change and the sheet conveying speed after the fixing device 609 decreases, as shown in FIG.
A certain space 610 is provided before 09, and the long paper is loosened between them to prevent a paper jam or the like from occurring.

Embodiment 6 An image forming apparatus according to Embodiment 6
When passing long paper, the heater of the pressure roller is turned on, and heat is applied to the long paper from both the heating roller and the pressure roller. FIG. 7B shows the configuration of the fixing device 708. The fixing device 708 has a heater 701 as shown in FIG.
And a pressure roller 710 containing a heater 702.

FIG. 7A is a control block diagram of an image forming apparatus according to the sixth embodiment, in which a heater 701 built in a heating roller 709 and a heater 702 built in a pressure roller 710 are provided.
And thermistors 703 and 704 for detecting the temperatures of the heaters 701 and 702, and a CP for controlling lighting of the heaters
U707 and A for supplying power to heaters 701 and 702
A C power supply 706 and an SSR 707 (switching switch) for switching ON / OFF of power supply to the heaters 701 and 702 based on a control signal from the CPU 705 are provided. SW1 indicates a switch for designating long paper passing when passing long papers other than the standard size.

The operation of the above configuration will be described. Normally, when a fixed-size transfer sheet is passed, only the heater 701 is turned on to heat the heating roller 709. On the other hand, when passing long paper other than the standard size, pressing the switch SW1 causes the CPU 705 to recognize the passage of the long paper, and in addition to the heater 701, the heater 7
02 is also turned on, and the pressure roller 710 in addition to the heating roller 709 is heated. Therefore, by turning on two heaters, even if the long paper loses some heat, both heaters 70
At 1,702, the temperature can be quickly raised, and the toner can be fixed reliably.

[Seventh Embodiment] An image forming apparatus according to a seventh embodiment is configured as follows.
When passing long paper, turn on the heater of the second fixing device.
In this state, fixing is performed by both the first fixing device and the second fixing device. FIG. 8B shows the first fixing device 80.
8 shows the arrangement of the second fixing device 809 and the second fixing device 809. As shown in the drawing, the first fixing device 808 is arranged on the upstream side of the sheet conveying path, and subsequently, the second fixing device 809 is arranged. Here, the heater of the first fixing device 808 is turned on at the same time when the power is turned on, and the heater of the second fixing device 809 is normally turned off.

FIG. 8A is a control block diagram of the image forming apparatus according to the seventh embodiment, in which a heater 801 built in the first fixing device 808 and a 802 built in the second fixing device 809 are shown. , Thermistors 803 and 804 for detecting the temperatures of the heaters 801 and 802, a CPU 807 for controlling the lighting of the heaters, an AC power supply 806 for supplying power to the heaters 801 and 802, and a heater based on control signals from the CPU 805. ON / OFF of power supply to 801 and 802
And an SSR 807 (switch) for switching off. SW1 indicates a switch for designating long paper passing when passing long papers other than the standard size.

The operation of the above configuration will be described. Normally, when a fixed-size transfer sheet is passed, only the heater 801 of the first fixing device 808 is turned on to perform the fixing process. On the other hand, when passing long papers other than the standard size, pressing switch SW1 causes
PU 805 recognizes the passing of the long paper, and the first fixing device 8
08, the heater 802 of the second fixing device 809 is also turned on, and the first fixing device 808 and the second fixing device 809 are turned on.
The fixing process is continuously performed by both the fixing device 809 and the fixing device 809.
Therefore, the long paper is fixed by the first fixing device 808 and then further fixed by the second fixing device 809, and even if the first fixing device 808 is slightly deprived of heat by the long paper, The fixing can be surely performed by the second fixing device 809.

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

According to the image forming apparatus of the present invention, a fixing device having a heater built in both a heating roller and a pressure roller can be used for a sheet having a longer length in the rotation direction of the roller than a fixed size sheet. Determining means for determining the passage of a certain length of paper; control means for turning on the heater of the pressure roller when the determination means determines that the long paper is to be passed;
Therefore, the toner can be reliably fixed even when the long paper is passed.

Further, the image forming apparatus of the present invention has a fixed size.
Discriminating means for discriminating whether or not the paper is longer than the long paper
When the first and the fixing device always heater during fixing is in the ON state, typically second fixing device is a heater is OFF state, when said discrimination means discriminates the sheet passing long paper, Previous
Because and a control means for a serial heater of the second fixing device in the ON state, even when fed a long paper, it is possible to fix the toner reliably.

[Brief description of the drawings]

FIG. 1A is a control block diagram of an image forming apparatus according to a first embodiment, and FIG. 1B is an explanatory diagram illustrating a configuration of a fixing device.

FIG. 2 is a control block diagram of an image forming apparatus according to a second embodiment.

FIG. 3 is a control block diagram of an image forming apparatus according to a third embodiment.

FIG. 4 is a schematic configuration diagram of an image forming apparatus according to a third embodiment.

FIG. 5 is a control block diagram of an image forming apparatus according to a fourth embodiment.

FIG. 6A is a control block diagram of an image forming apparatus according to a fifth embodiment, and FIG. 6B is an explanatory diagram illustrating a space in front of a fixing device.

FIG. 7A is a control block diagram of an image forming apparatus according to a sixth embodiment, and FIG. 7B is an explanatory diagram illustrating a configuration of a fixing device.

FIG. 8A shows a control block diagram of an image forming apparatus according to a seventh embodiment, and FIG. 8B shows a first fixing device and a second fixing device.
FIG. 3 is an explanatory diagram illustrating an arrangement of the fixing device.

[Explanation of symbols]

101 102 Heater 105 CPU 108 Fixing Device 109 Heating Roller 110 Pressure Roller 201 Fan Motor 203 CP
U 301 Clutch 303 CP
U 501 Main motor 502 Polygon motor 507 CPU 601 602 Drive system motor 607 CPU 701 702 Heater 705 CPU 709 Heating roller 710 Pressure roller 801 802 Heater 805 CPU 808 First fixing device 809 Second
Fixing device

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 13/20 G03G 15/20 G03G 15/00 303 G03G 21/00 370-502

Claims (2)

(57) [Claims] A fixing device having a heater built in both a heating roller and a pressure roller; and a feeding device for feeding a long sheet of paper having a longer length in a rotation direction of the roller than a fixed size sheet. An image forming apparatus, comprising: a determination unit for determining; and a control unit for turning on a heater of the pressure roller when the determination unit determines that long paper is to be passed. 2. An image forming apparatus having two fixing devices each including a heating roller and a pressure roller, comprising: a determination unit configured to determine whether or not a long sheet of a fixed size or more is passed; In this case, the first fixing device in which the heater is always in the ON state, the second fixing device in which the heater is normally in the OFF state, And a control unit for turning on the heater of the fixing device.