JPH09265242A - Image fixing device provided with shutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image fixing device provided with shutters, for preventing vibration caused by the opening/closing operations of the shutters from affecting an image. SOLUTION: The image fixing device 18 for fixing unfixed toner images formed by an image forming device on recording papers is provided with the shutters 5a and 5b for opening/closing the entrances for the recording papers of the image fixing device 18, a shutter opening timing detecting means for detecting the timing of opening the shutters 5a and 5b and a shutter close timing detecting means for detecting the timing of closing the shutters 5a and 5b. When coping or printing on the plural recording papers is executed, the opened states of the shutters 5a and 5b are held from the passing through the image forming device of the first recording paper to the ejection of the last recording paper from the image fixing device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image fixing device used in a copying machine, a printer, a facsimile, etc., and more particularly to an image fixing device having a shutter at the entrance and exit of recording paper.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for energy saving of products, and copying machines, printers, facsimiles, etc. (hereinafter collectively referred to as copying machines etc.)
Energy saving is also emphasized in the market. The biggest obstacle to energy saving in copiers using electrophotographic technology is the fixing process. How to reduce the energy consumption in the fixing process when the copying operation is not performed is energy saving. Greatly affects the degree of.

In the fixing process using the heat roller system, the surface temperature of the roller is constantly heated by the heater so as to be kept within the temperature range required for fixing. The larger the amount of heat dissipated to the outside of the fixing device, the more the heater is heated. The energy supplied will also increase.

In the past, about 40% of the energy lost by such an image fixing device is the dissipation of heat to the outside of the image fixing device due to convection, and for example, Japanese Patent Laid-Open Publication No.
In Japanese Patent Laid-Open No. 4-49073, the entire image fixing device is covered with a cover, and a shutter is provided at an opening (recording paper entrance / exit) through which recording paper passes, and the shutter is opened when the paper is passed and the shutter is closed when the paper is not passed. In this way, an image fixing device has been proposed in which the dissipation of heat to the outside of the image fixing device is prevented as much as possible.

[0005]

However, when copying or printing a plurality of sheets, the opening and closing operations of the shutter become frequent, which is a source of vibration and noise. Such vibrations
It propagates not only to the fixing process but also to other processes of electrophotography, and if it is bad, it causes image distortion. Especially, in a high-speed machine, the generated vibration becomes large, and there is a problem that image distortion cannot be ignored.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image fixing device having a shutter in which the vibration caused by the opening / closing operation of the shutter does not affect the image.

[0007]

In order to achieve the above object, the present invention according to claim 1 fixes an unfixed toner image on a recording paper on which an unfixed toner image is formed by an image forming device. In the image fixing device, which has a shutter for opening and closing the entrance / exit of recording paper, and when copying or printing a plurality of sheets, from the time when the first sheet is passed to the time when the last sheet is discharged. An image fixing device, characterized in that the shutter is kept open.

According to a second aspect of the present invention, in the image fixing apparatus according to the first aspect, shutter opening timing detecting means for detecting a timing for opening the shutter, and shutter closing for detecting a timing for closing the shutter. An image fixing device comprising: a timing detection unit.

According to a third aspect of the present invention, in the image fixing apparatus according to the second aspect, a conveying unit for conveying the recording sheet to the image forming apparatus and the recording sheet are discharged. The shutter opening timing detecting means sets the operation start of the conveying means as the shutter opening timing, and the shutter closing timing detecting means detects the last one. It is characterized in that the detection of the discharge of one sheet is used as the shutter closing timing.

According to a fourth aspect of the present invention, in the image fixing apparatus according to the second aspect, there is provided a transporting unit for transporting the recording paper, and the shutter opening timing detecting unit is the transporting unit. The operation is started at the shutter opening timing, the shutter closing timing detecting means has a time measuring means, and the shutter closing timing is set after a certain time has elapsed after the conveying means operates.

According to a fifth aspect of the present invention, in the image fixing apparatus according to the second aspect, the image forming apparatus and the image fixing apparatus further include control means for instructing start and stop of the operation of the image forming apparatus and the image fixing apparatus. The shutter opening timing detection means sets an instruction to start the operation of the image forming device and the image fixing device of the control means as a shutter opening timing, and the shutter closing timing detection means sets the image forming device and the image forming device of the control means. It is characterized in that the instruction to stop the operation of the image fixing device is set to the shutter closing timing.

In the present invention configured as described above, the shutter is opened before the first copy or print sheet enters the image forming process, and the shutter is closed after the last one is ejected. As a result, the shutter does not open and close during the process from image formation of copying or printing to fixing, so that the vibration does not affect the image.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described.

Hereinafter, the structure of an image fixing device to which the present invention is applied and the structure of a copying machine using the image fixing device will be described first, and then three modes of specific control and operation of the copying machine will be described. To do.

FIG. 1 is a schematic diagram of an image fixing device to which the present invention is applied, and FIG. 2 is a schematic diagram showing a main structure of a copying machine using the image fixing device.

In the image fixing device 18 shown in FIG. 1, the heating roller 1 and the pressure roller 2 are covered with an upper cover 3 and a lower cover 4, and an opening for recording paper to pass between the covers 3 and 4. Parts (exit and entrance) are provided. And
In this opening, shutters 5a and 5 interlocking with each other are provided.
b is provided. The shutters 5a and 5b are connected to a moving member 7 installed at a position lower than the conveyance path of the recording paper, and the moving member 7 is operated by one solenoid 8 to open and close the shutters 5a and 5b. Be seen. As a result, when the shutter is open, the shutter 5
The opening a opens to the inside of the image fixing device 18, and the shutter 5b opens to the outside, and also serves as a conveyance guide for the recording paper.
The direction indicated by A in the figure is the recording paper conveyance direction.

The moving member 7 and the solenoid 8 are driving means for opening and closing the shutters 5a and 5b as described above. One end of the moving member 7 is connected to the solenoid 8 and the other end is a frame of a copying machine or the like. It is connected to the spring member 11 fixed to the. The moving member 7 is made of a spring material 11.
The shutters 5a and 5b are closed while being pulled by
The shutters 5a and 5b are opened by being pulled leftward in the figure by the solenoid 8.

The shutter open / close state is detected by the shutter open / close sensor 12. The shutter opening / closing sensor 12 uses, for example, a limit switch or a photo interrupter.
Since 5b is interlocked, a limit switch is provided on the lower outside of the shutter 5b to detect opening / closing of the shutter.

The heating roller 1 inside the image fixing device 18 is
The recording paper is heated by a heat source (not shown), and is rotated by a motor and a rotation mechanism (not shown) to pass between the heating roller 1 and a pressure roller 2 (nip portion) that is driven by the rotation of the heating roller 1. As a result, the unfixed toner is fixed.
A temperature sensor 35 for detecting the fixing temperature is provided around the heating roller 1 and is controlled to a temperature required for fixing. Further, a claw member 36 for peeling the recording paper from the heating roller 1 is provided, and a paper discharge sensor 6 for detecting that the recording paper has been discharged downstream of the image fixing device 18 in the recording paper conveyance direction. Also, a paper discharge roller 19 is provided.

Here, the covers 3 and 4 and the shutter 5
The a and 5b are made of, for example, stainless steel, and are preferably covered with a heat insulating material so that the heat in the inside does not easily escape.

FIG. 2 is a diagram showing the structure of a general copying machine. The basic operation of this copying machine starts a copy execution operation by pressing (turning on) the start button 20 on the operation panel 25 shown in FIG. As a result, the recording paper is supplied from the cassette 28 by the rotation of the pickup roller 13, passes through the separating roller 14, and is stopped by the timing roller 15 and temporarily stands by. During this period, an original document to be copied is read by an image reading device provided on the upper part of the copying machine (not shown), and an electrostatic latent image is formed on the photoconductor 16 constituting the image forming device. Then, the electrostatic latent image formed on the photoconductor 16 is transferred to the timing roller 15
Is transferred as an unfixed toner image on the recording paper supplied in synchronization with the transfer timing. After the transfer, the recording paper is sent to the image fixing device 18 by the suction belt 17, and the unfixed toner image is fixed on the recording paper. The recording paper on which the image has been fixed is discharged by the discharge roller 19 and the copy operation is completed. Also, this copier has
In the vicinity of the timing roller 15, the timing roller 15
A timing sensor 31 for detecting that the recording paper has been supplied is provided.

Further, in this copying machine, in order to perform double-sided copying, the reversing device 33 for temporarily storing the recording paper discharged from the paper discharge roller 19 and turning the surface over, and the recording paper turned over again. A double-sided conveyance path 32 for returning to the timing roller 15 is provided.

The copy operation instruction is given from the operation panel 25 as shown in FIG. The operation panel 25 is provided with a start button 20 for instructing the execution of copying and a copy permission status display lamp 21 for indicating whether or not copying is possible. When the copy prohibition mode cannot accept the copy operation, the copy permission status indicator lamp 2
Reference numeral 1 indicates a copy prohibition mode, and even if the start button 20 is pressed, the copy operation is not executed. When the copy permission status display lamp 21 displays the copy permission mode and the start button 20 is pressed, the copy operation is performed as described above. Further, on the operation panel 25, the start button 2
0, a copy permission status display lamp 21, a display panel 22 for displaying various messages, a numeric keypad 23 for setting the number of copies, a function key 24 for designating variable copy, double-sided copy, and the like are provided. There is.

FIG. 4 is a block diagram of a control system for controlling the entire copying machine. A CPU (central control unit) 40 controls the entire copying machine, and is connected to a RAM 42 that stores control information and a ROM 41 that stores control programs and control data. Further, the CPU 40 has detection signals from the paper discharge sensor 6, the timing sensor 31, and the other sensors 30 (for example, the shutter open / close detection sensor 12 and the temperature sensor 35) installed in the copying machine, and the input keys ( For example, input signals from the start button 20, the ten-key pad 23, and the function keys 24) are input via an input interface (not shown). On the other hand, the CPU 40 controls the solenoid 8 for opening and closing the shutter and the control load 50 in the copying machine (for example, the image fixing device, the image reading device, each part of the device relating to the image forming operation such as the photoconductor 16 and each roller of the transport path). Is output through an output interface (not shown). Further, the CPU 40 has a built-in counter and timer for performing a count process and a timer process for a copy operation and a shutter opening / closing operation described later.

The first form of control of the copying machine will be described below. In the following description, the ON edge means a change in the state of the switch, sensor, signal, etc. when the state is switched from OFF to ON. Similarly O
FF edge is the state of switches, sensors, signals, etc.
The change in state when switching from N to OFF is referred to.

FIG. 5 is a flowchart of the main routine of the copying machine.

First, when a main switch (not shown) is pressed to turn on the power, various control contents of the copying machine are initialized in step (S1). C in step (S2)
An internal timer is started in the PU 40, and the control after step (S3) is executed within the time set by the internal timer.

In step (S3), the information keyed in from the operation panel 25 is accepted, and necessary information is displayed on the display panel 22 and the copy permission status display lamp 21 on the operation panel. In step (S4), the copy operation is controlled according to the control contents set in step (S3). In step (S5), control other than the control executed in step (S4), for example, control such as temperature adjustment of the image fixing device is executed.

Then, in step (S6), it is determined whether or not the internal timer has ended. If the internal timer has ended here, the process returns to step (S2) and the internal timer is started again.

FIG. 6 is a flow chart showing the control procedure of the copy operation subroutine. First, step (S1
In 1), it is determined whether or not the start button 20 is turned on, and when the detection of the ON edge is confirmed, the copy start flag is set to "1" in step (S12). If the detection of the on-edge is not confirmed, the step (S1
The process proceeds to step (S13) without executing 2).

In step (S13), it is determined whether or not the copy start flag is "1". If the copy start flag is "1", the steps after step (S14) are executed and the copy start flag is "1". If not, it returns to the main routine.

In step (S14), the control of the paper feed / conveyance system is executed, and in step (S15), other control, for example, a process of forming an unfixed toner image on the recording paper such as an image reading device or an image forming device. Executes control of surroundings.

In step (S16), the cumulative number of sheets counted up by the copy number counter CT1 described later, and
The number of sheets set on the operation panel 25 is compared to determine whether or not the copying operation for the final sheet is being performed. If the copying operation is not the final sheet, step (S17) is not executed and step (S18) Proceed to. On the other hand, if the copy operation is the final sheet, the process proceeds to step (S17) to set the copy start flag to "0", and then step (S18).
Then, the shutter opening / closing control subroutine described below is executed, and the process returns to the main routine.

FIG. 7 is a flow chart showing the procedure of the paper feed processing control subroutine. In this routine, first in step (S100), the paper feeding state indicated by the counter value of the state counter is checked. here,
The paper feed state is an initial state immediately after power-on and a standby state immediately after the end of copying operation, and the state is "0", and the following processing is executed according to the change of the paper feed state.

In the paper feeding state 0, first, in step (S101), the paper feeding permission flag is checked. The paper feed permission flag is set on the photoconductor 1 for the image forming process.
6 and the like starts to rotate and is set when the timing of the motor rising timer for waiting for stability is finished, and is reset when the recording paper is completely discharged. If the paper feed permission flag is set, the processing from step (S102) is performed, and if it is reset, the process returns to the copy operation routine.

At step (S102), the pickup roller 13 is turned on, then at step (S103) the separating roller 14 is turned on to start feeding from the cassette, and then at step (S104), the sheet feeding state is set to " Update to 1 ”.

In the paper feed state "1", an on check is performed to determine whether the timing sensor 31 is in the on state, that is, whether the recording paper is detected.
First, in step (S111), it is determined whether or not the leading edge of the recording paper that is moving from the paper feed cassette has reached the position where the timing sensor 31 is provided, and the timing sensor 3
When 1 is not on, that is, when the leading edge of the recording paper has not reached the position of the timing sensor 31, the process returns to the copy operation routine. On the other hand, when the timing sensor 31 is on and the leading edge of the recording paper reaches the position of the timing sensor 31, steps (S112) to step (S).
Execute up to 115).

In step (S112), the timing roller 15 is turned off, and in step (S113), the pickup roller 13 is turned off. The sorting roller 14 that was previously turned on continues. As a result, the recording paper is curved at the entrance of the timing roller 15, and a so-called paper loop for correcting the inclination of the recording paper with respect to the conveying direction is formed. After that, in step (S114), a paper loop timer for measuring the time for obtaining an appropriate paper loop is set, and in step (S11)
In 5), the paper feed state is set to "2" and the process returns to the copy operation routine.

In the paper feeding state "2", first, the paper loop timer is updated in step (S121). As a result, every time one routine of the main routine is executed, the time counting by the paper loop timer advances. Next, in step (S122), it is checked whether the count number of the paper loop timer has reached the predetermined value set in step (S114). If the count is not finished, return to the copy operation routine,
If the counting is completed, the step (S123) and the subsequent steps are executed. That is, in step (S123), the separating roller 14 is stopped (OFF), and in step (S1)
In 24), the paper feeding state is updated to "3".

In the paper feeding state "3", it is checked in step (S131) whether or not it is the registration timing for defining the alignment between the toner image on the photoconductor 16 and the recording paper. If it is not the registration timing, the process returns to the copy operation routine, and if it is the registration timing, the timing roller 15 is turned on in step (S132) to start moving the recording sheet to the transfer position.

Then, in step (S133),
When continuously feeding a plurality of recording papers, the paper feed interval timer is set to keep the interval between the recording papers constant, and the paper feed state is updated to "4" in step (S134).
Return to the copy operation routine.

In the paper feed state "4", the paper feed interval timer is updated in step (S141), and by repeating the paper feed state "4", the step (S141) corresponds to the time set in the paper feed interval timer. When the paper feed interval timer ends in step (S142), the paper feed state is returned to the initial state “0” in step (S143) so that the paper feed operation for the next recording paper is started. The copy number counter CT1 is counted up as the number of sheets fed in (S144).

FIG. 8 is a flow chart showing the procedure of the shutter opening / closing control subroutine. In this subroutine, the shutter is opened at the timing when the timing roller 15 is turned on, and the shutter is closed when the last sheet of paper passes the paper discharge sensor 6.

In the initial state immediately after the power is turned on and the standby state immediately after the end of the copying operation, the open / close state is "0", that is, the shutter is closed. First, in step (S20), it is determined whether the control for opening the shutter or the control for closing the shutter will be performed. When the open / closed state is “0”, the control from step (S21) to step (S23) is performed to perform the open control, and when the open / closed state is “1”, the close control is performed.
The control from step (S31) to step (S36) is performed.

As the control for opening, the operating state of the paper feed section in the above-mentioned paper feed processing control is used. First,
In step (S21), the state of the paper feed state flag is used as means for detecting the ON state of the timing roller 15, and when the paper feed state is other than "4", that is, when the on edge of the timing roller 15 is not detected, copy Return to the operation routine and the paper feeding state is "4"
That is, when the on-edge of the timing roller 15 is detected, the solenoid 8 is turned on to open the shutter in step (S22), and then the opening / closing stay is set to "1".
And returns to the copy operation routine.

As the control for closing, first, in step (S31), the discharge sensor 6 detects the off edge of the discharge of the recording paper. If not detected, the process returns to the copy operation routine and is repeated until the discharge of the recording paper is detected. When the discharge of the recording paper is detected, the step (S32)
To clear the paper discharge sensor 6 in preparation for the next recording paper discharge,
The number of discharged sheets counter CT2 is counted up as the number of recording sheets discharged in step (S33). Subsequently, at step (S34), the integrated number counted by the discharged sheet number counter CT2 is compared with the number set on the operation panel 25 to determine whether or not the discharged recording sheet is the last one. If the copy operation is not finished,
The process returns to the copy operation routine without executing step (S35) and step (S36). If the copy operation is completed, the solenoid 8 is turned off to close the shutter in step (S35), and the step (S3)
After the open / close state is returned to "0" in 6), the process returns to the copy operation routine.

The above is the control contents when the shutter is opened at the timing when the timing roller 15 is turned on and the shutter is closed when the last sheet passes through the discharge sensor 6 in the first embodiment, whereby the shutter is opened. When the number of continuous copies is made, the opening / closing operation without the shutter opening / closing work can be realized while the copying machine makes a continuous copy while ejecting the recording paper while keeping the holding time to a minimum.

Therefore, in the case of this first form,
The CPU 40 functions as a shutter opening timing detection unit that detects the operation timing of the timing roller 15 that is the conveyance unit by performing the above-described processing, and the discharge sensor 6 that is the discharge detection unit detects the last one sheet. It functions as a shutter closing timing detection unit that detects and uses this as the shutter closing timing.

Next, a second mode of shutter opening / closing control in the image fixing apparatus to which the present invention is applied will be described with reference to FIG.
This will be described with reference to FIG. In the second mode, among the copy operations, the procedure of the main routine shown in FIG. 5 in the first mode, the procedure of the copy operation subroutine shown in FIG. 6 and the sheet feeding process shown in FIG. The procedure of the control subroutine is the same as that of the first embodiment described above, and therefore its explanation is omitted. Therefore, only the second mode of the shutter opening / closing control will be described below.

FIG. 9 shows the procedure of the shutter opening / closing control in the second mode, which is the step (S1) in FIG.
It is a subroutine of 8).

In this shutter opening / closing control, the shutter is opened at the timing when the timing roller 15 is turned on, and the time from the opening of the shutter is counted to detect the timing at which the last sheet is ejected and the shutter is closed. .

First, in step (S40), it is determined whether the control for opening the shutter or the control for closing the shutter will be performed. When the open / close state is "0", the control from step (S41) to step (S44) is performed to perform the opening control, and when the open / close stay is "1", the control to close is performed to the step (S51). ) To step (S53).

As control for opening, first, at step (S41), whether or not the paper feed stay is "4" is used as the detection means for turning on the timing roller 15, and the paper feed stay is other than "4". That is, when the on-edge of the timing roller 15 is not detected, the process returns to the copy operation routine. When the paper feed state is "4", that is, when the on-edge of the timing roller 15 is detected, the timer TA indicates the time required from the opening of the shutter in step (S42) to the discharge of the last sheet from the fixing device 18. Set as the value of. Next step (S4
In step 3), the solenoid 8 is turned on to open the shutter, and the timer TA set in step S42 is set.
To be a star. Then, in step (S44), the open / close state is updated to "1" and the process returns to the copy operation routine.

As the control for closing, first, in step (S51), the end of the timer TA set in step (S42) is detected. If not detected, the process returns to the copy operation routine and is repeated until the end of the timer TA is detected. When the end of timer TA is detected,
In step (S52), the solenoid 8 is turned off to close the shutter, and in step (S53) the open / close stay is returned to "0", and then the process returns to the copy operation routine.

FIG. 10 is a flow chart showing a subroutine of a control procedure for setting the value of the timer TA in the step (S42).

First, at step (S61), the shutter opening time required when the number of copies is one is set to TA. Specifically, the time from when the leading edge of one recording sheet starts moving from the timing roller 15 to the transfer area until the trailing edge of the recording sheet is discharged from the fixing device is set.

Next, at step (S62), it is judged whether the number of copies is plural or not according to the information on the number of copies inputted from the operation panel 25, and if it is one, step (S63) is not executed. Go to step (S64).

If there are a plurality of sheets, step (S6
In step 3), TA is added for the time increased from the time set in step S61, and step TA6 is executed.
Proceed to 4). Specifically, the product of a value obtained by subtracting one copy from the number of copies is added to TA in the copy time required for one copy of the target copying machine.

Next, in step (S64), it is determined whether or not the copy is a double-sided copy. If the copy is single-sided, step (S65) is not executed and the process returns to the shutter opening / closing control routine. In the case of double-sided copying, TA is added to the time increased from the time set in step (S63) or step (S61) due to double-sided copying, and the process returns to the shutter opening / closing control routine. Specifically, the transport path 32 for double-sided copying
The product of the time that the recording paper passes (including the time in the reversing device 33) and the number of copies is added to TA.

As described above, in the second embodiment, the shutter is opened at the timing when the timing roller 15 is turned on, and the time from the opening of the shutter is measured to determine the last one.
This is the control content when the timing at which the sheets are discharged is detected and the shutter is closed. Therefore, in this embodiment, the CPU 40 functions as a shutter opening timing detection unit that detects the operation timing of the timing roller 15 that is the conveyance unit by performing the above-described processing, and the CPU 40 has a built-in timing unit. It functions as a shutter closing timing detection unit that uses the time for discharging the last one sheet measured by a certain timer as the shutter closing timing.

In the second embodiment, the opening and closing of the shutter is controlled by the timer starting from the on edge of the timing roller 15, so that the shutter opening time can be minimized.

In the second embodiment, the operation of the timing roller 15 is detected as the shutter opening timing, that is, whether or not the paper feeding state is "4" is detected. It may be detected that the state is other than 0. For example, when the paper feeding state is 1, the on-edge of the pickup roller 13 is detected.

Next, a third mode of the shutter opening / closing control in the image fixing device to which the present invention is applied will be described with reference to FIG.
This will be described with reference to FIG. It should be noted that, in the third mode, among the copy operations, FIG.
The procedure of the main routine shown in FIG. 7, the procedure of the copy operation subroutine shown in FIG. 6 and the procedure of the paper feed processing control subroutine shown in FIG. 7 are the same as those in the first embodiment described above, and therefore their explanations are omitted. Therefore, only the third mode of shutter opening / closing control will be described below.

FIG. 11 is a flowchart showing the procedure of shutter opening / closing control in the third embodiment, which is a subroutine of step (S18) in FIG.

In this embodiment, the start of a series of copy operations is detected from the on edge of the copy start flag, the shutter is opened, and the end of the series copy operation is detected at the off edge of the copy start flag, including the case of a plurality of sheets. Then, control is performed to close the shutter.

First, in the initial state immediately after the power is turned on and in the standby state immediately after the end of the copying operation, the copy start flag is "0", that is, the state of waiting for the input of the start button 20 for starting the copying operation. In this state, when the start button 20 is pressed to turn it on, as described above, the steps (S11) to (S1) in FIG.
2) is executed, the copy start flag is set to "1", each step is processed in the following order, and the shutter opening / closing control subroutine is started.

First, in step (S71), it is judged whether or not the copy start flag is "0", and if the copy start flag "1" is detected, the solenoid 8 is turned on to open the shutter in step (S73). , And returns to the copy operation routine.

Then, when the copy start flag is returned to "0" at the time when the copying of all the number of sheets is completed in the copy operation routine (step (S18) in FIG. 6), the copy start flag is set in step (S71). Since it is detected that it is [0], step (S72) follows.
Then, the solenoid 8 is turned off to close the shutter, and the process returns to the copy operation routine.

As described above, in the third embodiment, the shutter is opened by the detection of the on edge of the copy start flag as the detection means of the start of the continuous copy operation, and the case of plural sheets is detected-The end of the continuous copy operation is detected. This is the control content when the shutter is closed by detecting the off edge of the copy start flag as a means. Therefore, in this form, the CPU 4
0 executes the above processes to detect the state of the copy start flag as control means, that is, the shutter open timing detection means and shutter close timing detection for detecting the start and end of the operations of the image forming device and the image fixing device 18. Functions as a means. Then, in the third mode, when the heat insulation is not so strict, reliable opening and closing of the shutter can be realized by the simplest control as described above.

Although the embodiment to which the present invention is applied has been described by using the heat roller type image fixing device 18, the image fixing device having the preheating lamp 60 as shown in FIG. It may be used in a belt type image fixing device as shown in FIG. Further, although a copying machine has been described as an example in the above embodiment, the image fixing device of the present invention can be applied not only to a copying machine, but also to a facsimile, a laser printer, and the like.

[0071]

As described above, according to the present invention, an unfixed toner image is formed on a recording paper in an image forming device in the front stage of the image fixing device without using a vibration proof device in the shutter opening / closing mechanism. At this time, the shutter opening / closing operation is not performed, so that it is possible to remove the influence of the shutter opening / closing operation on the image.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an image fixing device to which the present invention is applied.

FIG. 2 is a schematic diagram of a configuration of a copying machine using the image fixing device.

FIG. 3 is an operation panel of the copying machine.

FIG. 4 is a block diagram of a control system that controls the entire copying machine.

FIG. 5 is a flowchart of a main routine showing a processing procedure of the copying machine.

FIG. 6 is a flowchart showing the procedure of a copy operation subroutine in the main routine shown in FIG.

7 is a flowchart showing a procedure of a paper feed processing control subroutine of the copy operation subroutine shown in FIG.

8 is a flowchart showing a procedure of a shutter opening / closing control subroutine of the copy operation subroutine shown in FIG.

9 is a flowchart showing a procedure of another form of a shutter opening / closing control subroutine of the copy operation subroutine shown in FIG.

10 is a flowchart showing a procedure of a timer TA setting subroutine of the shutter opening / closing control subroutine shown in FIG.

11 is a flowchart showing a procedure of still another form of a shutter opening / closing control subroutine of the copy operation subroutine shown in FIG.

FIG. 12 is a schematic view of an image fixing device of another embodiment to which the invention is applied.

FIG. 13 is a schematic view of an image fixing device according to still another embodiment of the invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Heating roller, 2 ... Pressure roller, 3 ... Top cover, 4 ... Bottom cover, 5a, 5b ... Shutter, 6 ... Paper discharge sensor, 7 ... Moving member, 8 ... Solenoid, 11 ... Spring material, 12 ... Opening / closing State detection sensor, 13 ... Pickup roller, 14 ... Separation roller, 15 ... Timing roller, 18 ... Image fixing device, 31 ... Timing sensor, 40 ... CPU.

Claims (5)

[Claims] 1. An image fixing device for fixing an unfixed toner image on a recording paper on which an unfixed toner image is formed by an image forming device, comprising a shutter for opening and closing a door of the recording paper, When copying or printing the first 1
From the time the sheets are passed until the last one is ejected,
An image fixing device, characterized in that the shutter is held open. 2. The image fixing device according to claim 1, further comprising: a shutter opening timing detecting unit that detects a timing of opening the shutter, and a shutter closing timing detecting unit that detects a timing of closing the shutter. . 3. A shutter opening timing detection unit, comprising: a conveyance unit configured to convey the recording sheet to the image forming apparatus; and a sheet ejection detection unit configured to detect that the recording sheet is ejected. It is characterized in that the operation start of the conveying means is the shutter opening timing, and the shutter closing timing detecting means sets the shutter closing timing when the paper discharge detecting means detects the last one paper discharge. The image fixing device according to claim 2. 4. A transport means for transporting the recording paper, wherein the shutter opening timing detecting means sets the operation start of the transporting means as a shutter opening timing, and the shutter closing timing detecting means comprises a timing means. 3. The shutter closing timing is set after a certain time has elapsed after the transporting means operates.
The image fixing device described. 5. The image forming apparatus and the image fixing apparatus further include control means for instructing start and stop of operation of the image forming apparatus and the image fixing apparatus, and the shutter opening timing detecting section includes the image forming apparatus and the image fixing apparatus of the control unit. The shutter start timing is set as the shutter start timing, and the shutter close timing detection unit sets the shutter close timing as the instruction to stop the operation of the image forming device and the image fixing device of the control unit. The image fixing device according to claim 2.