JP2604637B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a fixing device of an image forming apparatus such as a copying machine and a laser printer.

<Related Art> In a conventional fixing device of an image forming apparatus, there is a fixing device that heats a heating element of a fixing roller without turning a fixing roller and a pressure contact roller in contact after power is turned on. In the fixing device, when a normal fixing temperature is reached, preparation for image formation is completed, and thereafter, the power supply to the heating element of the fixing roller is controlled so as to maintain the temperature. When the image forming instruction signal is input, the fixing roller and the pressure roller are rotated in contact with each other to fix the transfer paper.

<Problems to be Solved by the Invention> However, in the above-described conventional technology, the input rotation of the fixing roller and the pressure contact roller starts due to the input of the image formation instruction signal, and the heat of the fixing roller is taken away by the pressure contact roller, and the fixing temperature is lower than the fixing temperature. The roller temperature drops. For this reason, a fixing failure may occur when an image is formed on the first transfer sheet. Alternatively, when waiting for the roller temperature to reach the fixing temperature again so as not to cause a fixing defect, it is necessary to energize the heating element of the fixing roller to increase the roller temperature. During this time, the image forming operation must be stopped. First, there is a problem that it takes a long time to form an image on the first transfer sheet.

In view of the above, an object of the present invention is to provide a fixing device that can prevent the temperature of the fixing roller from lowering below the fixing temperature when an image forming instruction is issued.

<Means for Solving the Problems> As shown in FIGS. 6 and 7, the problem solving means according to the present invention comprises a fixing roller 1 and a pressing roller 2 which presses against the fixing roller 1.
A heating element 3 for heating the fixing roller 1; a temperature detector 4 for detecting the temperature of the fixing roller 1; and a driving device 5 for driving the fixing roller 1 and the pressure roller 2 to rotate.
And a control device 6 for controlling the heating element 3 and the driving device 5 by an output signal of the temperature detector 4. The control device 6 sends an image formation preparation signal to the heating element 3 by turning on a power switch 15. an image forming preparation unit 16 for controlling the heating element 3 so that the temperature of the fixing roller 1 and the output is higher than the fixing temperature T ₀ fixing preheating temperature T _1, the print Sui Tutsi
A rotation controller 18 for operating the driving device 5 by the image formation instruction signal from the 17, the energization control means 19 is energized so that the heating element 3 to the fixing temperature T ₀ by the image formation instruction signal, the temperature setting of the conduction control to the heating element 3 is periodically set to the fixing preheating temperature T ₁ of the fixable temperature T ₀ every time a predetermined time has elapsed from the on the power switch 15 when no output of the image formation instruction signal Heating element 3
And a fixing standby unit 24 for controlling the image forming apparatus.

Another means for solving the problem is that the fixing standby means 24 controls the energization of the heating element 3 every time a fixed time elapses from the end of image formation when there is no output of the next image formation instruction signal after the end of image formation. and controls the heating element 3 so that the temperature setting is periodically set to the fixing preheating temperature T ₁ of the fixable temperature T _0.

<Operation> In the above-mentioned problem solving means, when the power switch 15 is turned on, the image forming preparing means 16 outputs an image forming preparing signal to the heating element 3. Then, the print Sui Tutsi 17 until the image formation instruction signal is output, the heating element 3 so as to maintain the fixing preheating temperature T ₁ is controlled.

Then, when the image formation instruction signal is input, the rotation control means 18 operates the driving device 5 to rotate the fixing roller 1. The energization control means 19 temperature than the control temperature of the fixing roller 1 from T ₁ is low but controlling the heating element 3 so that the temperature T ₀ fixable.

By controlling the heating element 3 as described above,
The temperature of the fixing roller 1 shows a temperature change as shown by a solid line A in FIG. 5, and the fixing roller 1 and the pressure roller 2 are rotated by an image forming instruction signal as shown by a dotted line B according to the conventional method. temperature is taken by the pressure roller 2, if lower than the fixable temperature T ₀ can be solved when was the problem.

Therefore, it is possible to prevent a fixing failure due to a decrease in the temperature of the fixing roller 1. Alternatively, it is possible to efficiently perform image formation by shortening the time until image formation of the first transfer sheet.

If the image forming instruction signal is not output within a certain period of time after the power switch 15 is turned on, the temperature of the power supply control to the heating element 3 is set by the fixing standby means 24 to the fixing preheating temperature T _1.
To change the fixing temperature T ₀ from. Further, if the image forming instruction signal is not output even after the lapse of a certain period of time, the temperature setting of the power supply control to the heating element 3 by the fixing standby unit 24 is reset to T ₀
It is changed to T ₁ from.

Repeating these, if any image formation instruction therebetween, performing control so that the temperature setting of the conduction control to the heating element 3 to T _0.

Further, after an image is formed also, until the next image forming instruction, the set temperature of the conduction control to the heating element 3 T ₀ and T ₁
And changes are made periodically.

Therefore, when image formation is instructed, it is possible to prevent the temperature of the fixing roller 1 from decreasing, and
When image formation is not performed for a long time, unnecessary power consumption can be avoided by periodically raising and lowering the roller temperature of the fixing roller 1.

<Embodiment> Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a control block diagram showing a first embodiment of the present invention.
FIG. 2 is a schematic diagram of the fixing device, FIG. 3 is a control circuit diagram for controlling the fixing temperature, FIG. 4 is a flowchart for controlling the energization of the heating element, and FIG. It is a figure showing operation timing.

As shown in FIGS. 1 and 2, the fixing device in the image forming apparatus of the present invention includes a fixing roller 1, a pressure roller 2 for pressing against the fixing roller 1, and a heating element 3 for heating the fixing roller 1.
A temperature detector 4 for detecting the temperature of the fixing roller 1, a driving device 5 for driving the fixing roller 1 and the pressure roller 2 to rotate, and a heating element 3 and a driving device 5 based on an output signal of the temperature detector 4. And a control device 6 for controlling,
The lower pressure roller 2 on the upper fixing roller 1 comes into contact with the roller, and the toner 8 transferred to the transfer paper 7 is fixed by the contact pressure and heat.

The fixing roller 1 is a hollow roller rotatable around a rotation shaft 9 in the image forming apparatus main body.
Reference numeral denotes a roller in which a center shaft 10 is supported so as to be vertically movable with respect to the image forming apparatus main body in opposition to the fixing roller 1. The pressing roller 2 is supported by the support piece 11 of the image forming apparatus and the central shaft.
A compression spring 13 is interposed between the bearing 10 and the bearing portion 12, and the pressing roller 2 is pressed against the fixing roller 1.

The heating element 3 is formed of a halogen lamp, and is arranged around a rotation shaft 9 of the fixing roller 1. And
The temperature detector 4 uses a thermistor and is disposed close to the outer surface of the fixing roller 1.

The driving device 5 includes a driving motor (not shown) for driving the rotation shaft 9 of the fixing roller 1 to rotate.

The control device 6 is a one-chip microcomputer having a data RAM and a program ROM, and performs control according to a control program stored in the ROM in advance. Then, the control device 6, as the first view, turned by the the heating element 3 outputs the image forming preparation signal temperature of the fixing roller 1 is fixable temperature T ₀ higher than the fixing preheat temperature of the power supply switch 15 T ₁ Image forming preparation means 16 for controlling the heating element 3 so as to achieve the above, rotation control means 18 for operating the driving device 5 by an image formation instruction signal from a print switch 17, and fixing of the heating element 3 by the image formation instruction signal. Energization control means for controlling energization to reach the possible temperature T ₀
19 and have been given.

As shown in FIG. 3, a control circuit for controlling the energization of the heating element 3 includes a CPU 6a of a control device 6 for detecting an output of the temperature detector 4 by analog input, and an output of a heating element ON signal from the CPU 6a. A triac 21 for controlling the phase of the AC power supply 20 applied to the heating element 3, a photo triac 22 as a switch element for turning on the triac 21 by an output signal from the CPU 6a, and a photo triac 22 for turning on the CPU 6a. And a NOT circuit 23 for operating by a signal.

Then, the CPU6a is follow the contents of the internal or external program ROM connexion, it does not reach the fixing temperature T ₀ or fixing preheating temperature T ₁ of the roller temperature is set, and outputs the heating element on signal The heating element 3 is energized to control the energization to reach the set temperature.

Further, the control device 6 has a function of controlling an image forming mode in accordance with an input signal from an operation unit (not shown), performing display control of a display unit, and controlling load related to image formation. Further, when the power roller temperature specified time in to since the ON does not reach the fixing preheating temperature T _1, it is determined that the trouble has occurred, a function of outputting the trouble code in the image forming preparation unit 16 It is impatient.

In the above configuration, the image forming preparation operation of the fixing device will be described based on the flowchart of FIG.

First, when the power switch 15 is turned on, the image forming preparation means 16 outputs an image forming preparation signal to the heating element 3 and, at the same time, in step S-1, the fixing temperature is completed within a specified time. when that does not reach the preheating temperature T _1, to set the timer t ₀ to trouble. In step S-2, determines whether the fixing temperature T has reached the fixing preheating temperature T _1, or timer t ₀ is set in step S-3 in step S-1 if it has not reached the Taimuatsupu not Is determined, and if the time is not up, step S-
At 4, the heating element 3 is turned on, and the process returns to step S-2. If the time is up, the heating element 3 is turned off in step S-5, and the occurrence of a trouble is notified to the image forming preparation means 16 in step S-6, and the process is terminated. This work is Step S-
The fixing temperature T is continued until it is determined that the above T ₁ at 2.

If it is determined that T ≧ T ₁ at step S-2, then turns off the heating element 3 at step S-7, step S-8 fixing device in the image forming preparation means 16 imaging ready and summer in Notify that. Then, to determine whether the image formation instruction signal from the print Sui Tutsi 17 at step S-9 is entered, if not entered, or the temperature detector 4 has detected the above T ₁ at step S-10 determine how and if above T ₁ to the off and step S-9 the heating element 3 at step S-12, does not reach the T ₁ step S
At -11, the heating element 3 is turned on, the process returns to step S-9, and this operation is repeated until an image formation is instructed.

If it is determined in step S-9 that the image formation has been instructed, the drive device 5 is operated by the rotation control means 18, and
The fixing roller 1 is rotated. The energization control means 19 transfers the control temperature of the fixing roller 1 to a temperature T ₀ temperature as possible, but low fixing than the T _1. The control is the same as steps S-10 to S-12, and step S-13.
Temperature detector 4 determines whether or not to detect the T ₀ higher by, if T ₀ or the step S-15 to the heating element 3 is turned off at step S-13, has not been reached T ₀ Step S
At -14, the heating element 3 is turned on, and the process returns to step S-13. Thereafter, this operation is repeated.

By controlling the energization of the heating element 3 as described above, the temperature of the fixing roller 1 shows a temperature change as shown by a solid line A in FIG. A fixing roller 1 and a pressure roller 2
There is rotated, the temperature of the fixing roller 1 is taken by the pressure roller 2 and lower than the fixable temperature T ₀ problems when had can be solved.

Therefore, it is possible to prevent a fixing failure due to a decrease in the temperature of the fixing roller 1. Alternatively, it is possible to efficiently perform image formation by shortening the time until image formation of the first transfer sheet.

[Second embodiment] Fig. 6 is a control block diagram showing a second embodiment of the present invention.
FIG. 7 is a flowchart for controlling the energization of the heating element.

As shown in FIG. 6, the control device 6 of the fixing device of this embodiment
When the power switch 15 is turned on, an image formation preparation signal is output to the heating element 3 so that the temperature of the fixing roller 1 becomes a fixing feasible temperature.
Image forming preparation means 16 for controlling the heating element 3 to have a fixing preheating temperature T ₁ higher than T _0, rotation control means 18 for operating the driving device 5 by an image forming instruction signal from a print switch 17, Energization control means 19 for controlling energization of the heating element 3 by the formation instruction signal so that the temperature of the fixing roller 1 becomes the feasible fixing temperature T _0, and energization of the heating element 3 every time a predetermined time elapses after the power switch 15 is turned on. fixing stand unit temperature setting of the control to control the heating element 3 to be periodically set to the fixing preheating temperature T ₁ of the fixable temperature T ₀ 24
It is a thing that was given.

The fixing stand unit 24 counts the predetermined time t ₁ from the on the power switch 15, a predetermined time further comprising a time t ₁
counts t _2, thereafter it has a timer function to repeat them, to change the temperature setting of the conduction control to the heating element 3 at regular time intervals.

The other structure is the same as that of the first embodiment, and the image forming preparation operation of this embodiment is performed in the same manner as the first embodiment up to step S-8, as shown in the flowchart of FIG. .

When the preparation for image formation is completed, step S-16 is performed.
Fixable temperature the temperature setting of the energization control of the fixing stand unit 24 to the heating element 3 after a predetermined time from the fixing preheating temperature T ₁ of at
To set the timer t ₁ in order to change to T _0.

At step S-9, to determine whether the image formation instruction signal is inputted from the print Sui Tutsi 17, if not input, whether the temperature detector 4 has detected the above T ₁ at step S-10 It discriminated, if above T _1, turns off the heating element 3 to step S-12, to turn on the heating element 3 does not reach the T _1. Then, at step S-17, t ₁
It is determined whether the time has elapsed, and if not, the process returns to step S-9. If passed, the fixing stand unit 24 at the same time move the control temperature of the fixing roller 1 from T ₁ to T _0, T ₀ the temperature setting of the conduction control to the heating element 3 after a predetermined time at step S-18 timer that allows you to change to a T ₁ from
Setting the t _2. Then, from step S-19 to step S-
The same operation as step S-. 9 to step S-17 over the 23 performs the setting temperature with respect to T _0. At step S-23
determines whether the elapsed t ₂ hours, when not reached returns to step S-19, returns the elapsed set again if the temperature in the step S-16 was changed to T _1.

While repeating these steps, it is determined in step S-9 or step S-19 whether an image formation instruction has been issued. If there is an instruction, the process proceeds to step S-13 to set the temperature for controlling the energization of the heating element 3. It becomes T ₀ performs the control.

Therefore, in the present embodiment, the same effects as those in the first embodiment can be obtained. Further, when image formation is not performed for a long time, unnecessary power consumption can be avoided by periodically raising and lowering the temperature of the fixing roller 1.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention.

For example, as in the second embodiment, fixing a change of temperature setting of the conduction control to the heating element 3 without repeated several times, from the one-time fixing preheat temperatures T _1, as shown in step S-16 of FIG. 8 The power consumption may be further reduced by changing the temperature to the possible temperature T ₀ and performing control thereafter to the temperature T ₀ .

Instead of repeatedly raising and lowering the set temperature of the power supply control to the heating element 3 only when the power switch 15 is turned on, an image forming instruction signal is output from the print switch 17 as shown in FIG. After the completion of the image formation, it is confirmed in step S-24 that the image formation is completed, and then in step S-16.
To return again to change the preset temperature T _1, the conduction control to the heating element 3 so as to repeatedly up and down by the roller temperature of the fixing roller 1 row of connexion may.

<Effects of the Invention> As is clear from the above description, according to the present invention, the control device that controls the heating element and the driving device based on the output signal of the temperature detector sends an image formation preparation signal to the heating element when the power switch is turned on. Image forming preparation means for controlling the heating element so that the temperature of the fixing roller becomes a fixing preheating temperature higher than the feasible fixing temperature, and rotation control means for operating the driving device by an image forming instruction signal from a print switch. Power supply control means for controlling power supply of the heating element so that the temperature of the fixing roller becomes a fixable temperature by the image formation instruction signal, and from when a power switch is turned on when there is no output of the image formation instruction signal, or after completion of image formation. When there is no output of the next image formation instruction signal, the temperature setting of the energization control to the heating element is performed every time a predetermined time elapses from the end of image formation. It has a fixing standby unit that controls the heating element so as to periodically set the fixing preheating temperature and the fixing possible temperature, so that the roller temperature is maintained at a temperature higher than the fixing possible temperature until an image forming instruction is issued. The fixing roller and the pressure contact roller are controlled by the image forming instruction signal, and the temperature of the fixing roller is prevented from being robbed by the pressure contact roller, thereby preventing the temperature from lowering below the feasible fixing temperature.

Therefore, it is possible to prevent a fixing failure due to a decrease in the temperature of the fixing roller. Alternatively, it is possible to efficiently perform image formation by shortening the time until image formation of the first transfer sheet.

When image formation is not performed for a long time, the temperature of the fixing roller is periodically increased and decreased at regular intervals,
Unnecessary power consumption can be avoided. In addition, since the temperature of the fixing roller is always maintained higher than the fixable temperature, the fixing roller is always in a fixable state even when the image formation is started, and has an excellent effect that no fixing failure occurs.

[Brief description of the drawings]

FIG. 1 is a control block diagram showing a first embodiment of the present invention, FIG. 2 is a schematic diagram of a fixing device, FIG. 3 is a control circuit diagram for controlling a fixing temperature, and FIG. FIG. 5 is a diagram showing a change in roller temperature and operation timing of a driving device, FIG. 6 is a control block diagram showing a second embodiment of the present invention, and FIG. 7 is a diagram showing control of energization of a heating element. FIG. 8 is a flow chart for controlling the energization of a heating element according to another embodiment of the present invention.
FIG. 9 is a flowchart for controlling the energization of the heating element of another embodiment. 1: fixing roller, 2: pressure contact roller, 3: heating element, 4: temperature detector, 5: drive device, 6: control device, 15: power switch, 16: image forming preparation means, 17: print switch, 18: Rotation control means, 19: energization control means, 24: fixing standby means.

Claims (2)

(57) [Claims] A fixing roller for pressing the fixing roller; a heating element for heating the fixing roller; a temperature detector for detecting a temperature of the fixing roller; and a driving device for rotating the fixing roller and the pressing roller. A driving device for controlling the heating element and the driving device based on an output signal of the temperature detector, and the control device outputs an image formation preparation signal to the heating element when the power switch is turned on to fix the heating device. Image forming preparation means for controlling a heating element so that the temperature of the roller becomes a fixing preheating temperature higher than a fixable temperature; rotation control means for operating the driving device by an image formation instruction signal from a print switch; and the image formation instruction A power supply control means for controlling the power supply so that the temperature of the heating element can be fixed by a signal; and a power supply switch when the image formation instruction signal is not output. And a fixing standby means for controlling the heating element so that the temperature setting of the power supply control to the heating element is periodically set to the fixing preheating temperature and the fixable temperature every time a predetermined time elapses after the switch is turned on. A fixing device characterized by the above-mentioned. 2. A fixing roller, a pressure roller for pressing against the fixing roller, a heating element for heating the fixing roller, a temperature detector for detecting a temperature of the fixing roller, and a drive for rotating the fixing roller and the pressure roller. A driving device for controlling the heating element and the driving device based on an output signal of the temperature detector, and the control device outputs an image formation preparation signal to the heating element by turning on a power switch. Image forming preparation means for controlling a heating element so that the temperature of the fixing roller becomes a fixing preheating temperature higher than a fixable temperature; rotation control means for operating the driving device in response to an image forming instruction signal from a print switch; An energization control means for controlling the energization of the heating element to a fixable temperature by the instruction signal, and an output of the next image formation instruction signal after completion of image formation. And a fixing standby means for controlling the heating element so that the temperature setting of the power supply control to the heating element is periodically set to the preheating temperature for fixing and the feasible fixing temperature every time a predetermined time elapses from the end of image formation. A fixing device characterized in that the fixing device is provided.