JPS63301080A - Fixing device for recording equipment - Google Patents

Abstract

PURPOSE:To prevent a sheet from wrinkling owing to its curvature as a result of fixation processing by controlling the temperature of a heating means and switching the target temperature of the control automatically according to a paper feed mode set by a paper feed mode switching means. CONSTITUTION:The paper feed mode switching means K0 is provided which controls the temperature of the heating means HT of a fixing device and sets a paper feed mode according to the number of times of the passage of the sheet in the fixing device, and the target temperature of the fixing device is adjusted automatically according to the paper feed mode of the sheet. Then when double-sided copying processing is performed, the roll temperature of the fixing device is set lower in 1st-surface copying processing than usual, but set larger in 2nd-surface copying processing than in the case of the 1st surface. Consequently, even when the fixation processing is performed plural times for one sheet, the sheet is prevented from wrinkling.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a recording device equipped with a fixing device, such as a copying machine, and particularly relates to prevention of wrinkles caused on a sheet on which an image is recorded due to warpage. .

[Prior Art] In general copying machines, a hot roll fixing method is used for fixing processing. The fixing device of this type of copying machine is equipped with two rolls arranged opposite to each other and a heater for heating these rolls. The sheet onto which the image to be fixed has been transferred is pressed under high temperature while passing between two rolls, so that the image is fixed on the sheet.

Incidentally, in a copying machine equipped with this type of fixing device, the sheet passing through the fixing bag device often warps due to pressure and heat. In normal copy processing, the sheet that has passed through the fixing device is immediately ejected to a paper ejection tray, so sheet warping is often not a particular problem.

However, for example, in a copying machine that transfers an image to both the front and back sides of a recording sheet, the image is transferred to one surface, the sheet passes through a fixing device, and is sent again to the image reproduction mechanism via an intermediate tray, and then the back side of the sheet is transferred. Performs recording processing. In such a case, if the sheet that has passed through the fixing device is significantly warped, problems will occur in various sheet processing mechanisms within the copying machine. especially.

When the sheet passes through the fixing device for the second time, the sheet gripping position of the fixing roll becomes unstable, and wrinkles are likely to occur in the sheet.

In order to eliminate this kind of inconvenience, methods have been proposed in the past to correct the warping of a warped sheet, and to transport the sheet while sucking it with negative pressure air to eliminate the negative effects of warping. ing. However, if this type of method is used, the structure of the device becomes complicated, and an increase in the cost of the device is unavoidable. Moreover, the reality is that even when this type of method is used, it is not possible to completely eliminate wrinkles on the sheet that occur during double-sided copying.

For example, in a copying machine that can make monochrome copies using color toner, when recording images of multiple colors on a single sheet, a fixing process is performed on the same sheet in order to overlap the recorded images of each color. As with double-sided copying, since the copying process that includes
1 is likely to occur.

[Object of the Invention] An object of the present invention is to prevent the occurrence of wrinkles in a sheet caused by warping of the sheet due to fixing processing.

[Structure of the Invention] In order to achieve the above object, the present invention provides a communication system for controlling the temperature of the heating means of the fixing device and setting a paper feeding mode that is set according to the number of times a sheet passes through the fixing device. A paper mode switching means is provided to automatically adjust the target temperature in the fixing device according to the sheet passing mode.

The fixability of an image on a recording sheet tends to improve as the sheet pressing force and fixing roll temperature in the fixing device increase. However, the amount of warpage that occurs in the sheet that passes through the fixing device also increases as the sheet pressing force and fixing roll temperature in the fixing device increase. In other words,
If the temperature of the fixing roll is set high in order to obtain good fixing performance, the sheet becomes more warped and wrinkles are likely to occur in the sheet. On the other hand, if the fixing roll temperature is set low in order to prevent sheet wrinkles, image fixability deteriorates.

Therefore, when fixing the sheet pressing force and fixing roll temperature at a constant state, it is necessary to set the fixing roll temperature high to give priority to fixing performance, so the occurrence of sheet wrinkles is unavoidable. .

However, wrinkles are likely to occur on sheets when double-sided copying is performed or when copying is repeated multiple times on the same sheet. In this type of situation, the sheet will pass through the fuser multiple times. Therefore, 1. For example, when performing two fixing processes in succession, 1.
Even if the fixation of the image during the fixing process is somewhat poor,
By passing through the fixing process of the re-opening, a fixing property of 1 minute can be obtained.

Therefore, in a preferred embodiment described later, when double-sided copy processing is performed, the roll temperature in the fixing device is set lower than usual in the first side (front side) copying process, and the second side ('pS In the copying process for the first side, the roll temperature in the fixing device is set higher than that for the first side. In this way, the warping that occurs on the sheet when the first side copying process is completed can be suppressed to a relatively small amount, so there is a risk that wrinkles will occur on the sheet when the second side is subjected to the copying process. will disappear.

Moreover, since the second fixing process is not performed on the image on the first side during the fixing process on the second side, sufficient fixability can be obtained for the image on the first side as well.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[Embodiment] FIG. 1 shows one type of copying machine embodying the present invention. This will be explained with reference to FIG. Briefly speaking, this copying machine consists of a copying machine body, an ADF (original feeder) 60. It is composed of a group of optional units such as a sorter 702 and a double-sided processing device 80. The paper feed system that supplies recording sheets has five stages. 21°22.23 and 24 are the first
These are cassettes provided in the paper feeding system, the second paper feeding system, the third paper feeding system, and the fourth paper feeding system, and 25 is the 1-lay of the fifth paper feeding system. When copying the second side of double-sided copy processing, that is, the back side, sheets are fed from an intermediate tray provided in the double-sided processing device 80.

A contact glass 1 on which a document is placed is provided at the top of the main body of the copying machine, and an optical scanning system 30 is provided below the contact glass 1. The optical scanning system 30 includes an exposure lamp 31. 1st
Mirror 32. Second mirror 33° Third mirror 34. Lens 35. A fourth mirror is provided with a 36° slit 37, etc. When performing document reading scanning, the first
The carriage and the second carriage carrying the third mirror 33 and the fourth mirror 34 are mechanically driven to scan at a relative speed of 2:1. The lens 35 is a zoom lens, and by driving it with a motor, the imaging magnification of the optical system can be changed.

The light emitted from the exposure lamp 31 passes through the first mirror 32, the second mirror 33, and so on. Third mirror 34. Lens 35° 4th mirror 3
6 and a slit 37, the image is formed on the photoreceptor drum lz2.

Around the photoreceptor drum 2, there are a main charger 3 and an eraser 4. @Image 5. Pre-transfer static elimination lamp 6, transfer charger 7, separation charger 8. It is equipped with a dangling unit 9, etc.

The image reproduction process is explained by Uc. The surface of the photosensitive drum 2 is uniformly charged to a predetermined high potential by the discharge of the main charger 3. The charge in the portion not used for image reproduction is erased by the eraser 4. photoreceptor dora tz
When the reflected light from the original is irradiated onto the charged surface of 2,
Depending on the intensity of the irradiated light, the potential of that part changes (
descend. The photoreceptor drum l'=2 rotates in the direction shown by the arrow in the figure, and in synchronization with this, the optical scanning system 30 sequentially scans the document surface, so that the surface of the photoreceptor drum 2 has the density (light) of the document image. A potential distribution corresponding to the reflectance) distribution, that is, an electrostatic latent image is formed.

When the portion on which the electrostatic latent image is formed passes near the developing device 5,
The toner in the developing device 5 is attracted to the surface of the photoreceptor 2 according to the potential distribution, thereby developing the electrostatic latent image, and a visible image corresponding to the electrostatic latent image is formed on the photoreceptor drum 2-. be done. On the other hand, in synchronization with the progress of the copy process, recording sheets are supplied from any one of the five paper feed systems and intermediate trays. This recording sheet is the registration roller 27
The photoreceptor drum ts2 is fed through the photoreceptor drum ts2 at a predetermined timing so as to overlap the surface of the photoreceptor drum ts2.

Then, the transfer charger 7 transfers the photoreceptor to the photoreceptor 2.
The upper visible image (toner image) is transferred to the recording sheet side, and the recording sheet to which the visible image has been transferred is further separated from the photoreceptor drums 1 and 2 by a separation charger 8. The separated recording sheets are transported to a fixing device 12 by a transport belt 11. Passing through the fuser 12, the toner image on the recording sheet is fixed onto the recording sheet by heat within a constant M'IJ 12. The recording sheet that has been fixed passes through a predetermined paper ejection path and is delivered to the intermediate 1 in the sorter 70 or the duplex processing device 80.
- Ejected into Ray.

FIG. 2 shows a specific configuration of the fixing device 12.

Referring to FIG. 2, the fixing device 12 includes a fixing roller 12a and a pressure roller 12b, which are arranged opposite to each other. These rollers are rotatably supported by shafts arranged at the center of each, and when performing the fixing process, the fixing roller 12a and the pressure roller 1
2b are rotated clockwise and counterclockwise, respectively. The sheet undergoing the fixing process is subjected to the fixing process when passing between the fixing roller 12a and the pressure roller L2b.

A heater IT is provided at the center of the fixing roller 12a, which heats the fixing roller 12a to a high temperature.

The pressure roller 12b is movable in the vertical direction, and is supported so as to be pushed up by a pressure cam 12f disposed below it.

A pressure adjustment mechanism 50 is arranged at the tip of the pressure cam 12f.

In addition, 12c is a coating felt for applying silicone oil to the fixing roller 12a, 12d is a thermistor for detecting the temperature of the fixing roller, 12e is a fixing device, and 12i
is the paper ejection sensor.

FIG. 3 shows the appearance of an operation board placed on the top surface of the main body of the copying machine shown in FIG. 1.

Referring to FIG. 3, this operation board has a large number of key switches KO, Kl, 2. 3. to 4a.

K 4 b, K 5, K 6 a r K 6
b , K 7 r K 8 , K 9 a rK
9 b, to 9. c, K I O, K l 1. K12
a, K 12b.

K13. KC, KS, #, KI and KT and a number of indicators DO, D1, 02 . D3. D4. It is equipped with D5° etc.

This section briefly explains the functions of the various typical key switches provided on the operation board.

KO is a key for setting an appropriate sheet pressure force on the fixing device according to the single sheet pass mode, and is operated when copying the same recording sheet twice or more by manual operation.

K1 is a key for specifying the operation mode of the sorter 70, and by operating this key, it is possible to specify any one of a fixed mode (using two seeds), a sort mode, and a stack mode.

K3 is a key for specifying the operation mode of the document conveying device 60, and by this operation, one of manual document setting mode, ADF mode, and 5ADF mode can be specified.

K4a and K4b are keys for specifying the front and back margin positions, respectively.

K6a, 6b, 9a, 9b and 9c are.

Used to specify copy magnification.

K7 is used to specify the copy mode. In this example,
You can specify either the normal copy mode (single-sided mode), two-sided A mode, or two-sided B mode.

K8 and Kll are used to specify the document size and paper feed system selection, respectively.

KIO is a numeric keypad and is used to specify the number of copies.

K12a and Kl 2b are used to specify copy density.

KC is the clear/stop key, and Chinki-KIO
This is used to clear the number of copies specified and to instruct to stop the copy operation.

KS is a key for instructing to start printing.

A brief explanation of typical indicators provided on the operation board will be given below.

The DO is made up of three light emitting diodes, and the key KO
Displays the paper feeding mode specified by.

Dl is a 7-segment, 2-digit numerical display.

In the normal operation mode, the set value for the number of copies per copy is displayed during standby, and the number of copies per copy is displayed during copying.

D2 displays the copy density setting state.

D3 displays the paper size, paper orientation, and selected paper feed system for each paper feed system.

D4 is a 7-segment, 3-digit numerical display.

In normal operation mode, the copy magnification is displayed at 1% A4.

D5 displays the designated document size.

FIG. 4a shows a schematic configuration of the electrical equipment section of the copying machine shown in FIG. 1.

Referring to FIG. 4a, main controller 200 includes a microprocessor 210. Read-only memory (ROM) 22
0. Read/write mail 11-re (RAM) 230, parallel ■ 10240. Serial l10250, A/D converter 260. A timer 270 and nonvolatile RAM 280 are provided.

The main control bag vi200 includes an operation board 310. Optical system control board 320. Lamp control board 330° heater control board 34o, high voltage power supply unit 350, motor driver 3602 position sensor S E )-1.

Paper feed unit 365. Driver 370, 380° signal processing circuit 390. Sorter 70. An ADF 60 and a double-sided processing device 80 are connected.

The operation board 310 includes various key switches and indicators shown in FIG. The optical system control board 320 is
An electric motor M7 that performs sub-scanning driving of the optical scanning system and an electric motor M2 that adjusts the magnification of the zoom lens 35 are controlled. The lamp control board 330 controls the amount of light from the exposure lamp 31.

The high voltage power supply unit 350 generates high voltage power to be applied to the main charger 3, the transfer charger 7, the separation charger 8, and the bias electrode 5a of the developing device.

FIG. 4b shows the configuration of the heater control board 340 of FIG. 4a. Referring to FIG. 4b, heater 11T has four
It consists of a combination of two heaters connected in row a. This heater IIT is connected to an AC power line (AClooV) via a triac TR. This triac TR is controlled on/off by a photocoupler PC composed of a light emitting diode and a photothyristor.

Control signal line TI connected to photocoupler PC
'r When ON is ■(, the PC turns off and the triac T
R is turned off, and power to the heater)-IT is cut off.

When the signal line tl T ON becomes L, the PC is turned on, the triac TR is turned on, and the heater 1-IT is energized. A thermistor I-IT is connected near the heater HT. The control signal line HT ON is connected to the output port of the main controller 200, and the thermistor TH is
It is connected to an analog signal input terminal of the A/D converter 260.

FIG. 5 shows a schematic operation of the main controller 200 shown in FIG. 4a, and details of some processes included in the process in FIG. 5 are shown in FIGS. 6a, 6b, and 6c.

This is shown in Figures 6d and 6e. Below, the main controller 200
Explain the operation.

First, refer to FIG. 5. When the power is turned on,

First, initialize the device. That is, read/write memory 2
The contents of 30 are cleared, the boat status is cleared, control setting values in the initial state are set in various control units, and the copying machine is set to a state in which copying operation is possible. After waiting for the copy operation to become possible, the process shifts to standby processing.

In standby processing, the status of various input ports is read.

Processing and output port control according to various key human power.

Communication processing with various control units, operation board 310
Controls the various displays provided on the machine.

This waiting process is repeatedly executed until the star 1 flag FS becomes rr III.

Part of the contents of the "key manual input" subroutine included in the standby process is shown in FIG. 6a. Please refer to FIG. 6a.

When the numeric keypad KIO is turned on, the flag F1 is checked, and if it is LL OII, the value of the pressed key is stored in the key register RKI and the flag Fl is set to ``1'', and if Fl is ``1'', Furthermore, check the flag FIO, and if it is ``I11'', transfer the contents of the key register RKI to the key register RKIO, store the value of the pressed key in RKI, and set the flag F10 to 111 '1.
Set to .

When clear key KG is turned on, flag F1 and FIO
is reset to '0'' and registers RKl and RKIO are cleared to 0. When the start key KS is turned on, the flag FS is set to II I 11.

When 7 is turned on to the duplex key, the duplex mode register MDS
Increment (+1) the contents of. However, if register MDS exceeds 2, the contents of MDS are cleared to 0. Note that 0°1 and 2 of register MDS are respectively
Compatible with single-sided copy mode, double-sided A copy mode, and double-sided B copy mode.

Also, when the key KO is turned on, the fixing pressure register Rfj
Increment the contents of x by 1-. However, if the content of Rfix is equal to 3, 1 is stored in the register Rfix.

Returning to FIG. 1, the explanation will continue. Flag FS is rr 1
When it reaches u, that is, when the start key KS is turned on.

End the standby process and proceed to the next process. first.

Store the value of RKIOX 10 + RK l in the copy number register N5et. Next, double-sided mode register MD
The contents of S are checked, and processing proceeds according to the contents.

When MDS is O, that is, when single-sided mode (normal mode) is specified, refer to table TBT- and register R
A value corresponding to the contents of fix is read and stored in the fixing target temperature register TMP. Next, one-sided motor”
Execute processing.

When MDS is 1, that is, when the double-sided Δ copy mode is specified, the flag F5ide is reset to 10'', the fixed value TI is stored in the register TMP, and the ``duplex Δ mote'' process is executed. .

When MDS is 2, that is, when double-sided B copy mode is specified, the flag Fside is reset to "o" and the fixed value Tl is stored in the register TMP.

Execute "Double-sided B mode" processing.

In this example, the contents of register TMP when the contents of Rfix are 3, 2, and l, that is, T[11, (3), T1
The value of 1t, (2) and Tnl(+) is TIIL(3)
< TnL (2) < T13L (1) (7). In other words, the heater target temperature of the fixing device 12 is Rfi
When the value of x is 3, it is the smallest, and as it decreases to 2°1, the target temperature increases. In this example, TM
When the contents of r) are Tnl and (1), the fixing temperature is set to the same level as the fixing temperature normally employed in general copying machines.

The contents of the "single-sided mode" processing shown in FIG. 5 are explained in Section 6b.
As shown in the figure. In this process, first, the original is positioned at a predetermined position on the contact glass 11, and the copy number counter N
Clear copY to 0. Next, the contents of the one-copy counter Neopy are counted as the number of copies and compared with the contents of the register Ns.

If Ncopy<N5et, then paper is fed from the cassette (one selected from the first to fifth paper feeding systems) and a known copying process is executed. When the copying process is finished, the copy sheet is ejected to the sorter 70,
The copy counter Ncopy is incremented and the process returns to step S1.

When N copy = N seL in step S1, the operation mode of the document conveyance device 60 is checked. A.D.
In F mode (a mode in which documents are conveyed continuously),
Furthermore, the presence or absence of a document on the device 60 is checked.

If there is a document, transport the document and position it on the contact glass 1, and place it on the copy counter N.
Clear copy to 0 and repeat the copy operation.

When N copy = N sej in step S1, if the document transport device 60 is not in the ΔDF mode or if there is no document on the device 60, the process advances to step S2.

In step S2, the contents of the register Rfix are checked. Then, if the content of Rfix is other than 0, the content is decremented (-1).

Note that the contents of the register Rfix are stored in the nonvolatile RAM 280 shown in FIG. 4a. Therefore, even if the power to the copying machine is cut off, the contents are retained.

In the initial state, the content of Rfix is 1, so the fixing process is performed with 5 normal fixing temperature set as the target value, but if you operate the key KO and set the content of Rfix to a value other than 1, The fixing temperature target value is set lower than usual. Such an operation is performed in the following cases.

If the tll-color toner is set in the developing device 5, the other colors will be reproduced. Therefore, by superimposing images reproduced with toners of various colors on one sheet 1 to 1, it is possible to reproduce a multi-color copy image. In such a case, the same sheet is repeatedly fed to the copying machine and image reproduction processing and fixing processing are performed multiple times. However, when the fixing process is performed multiple times, wrinkles are likely to occur in the sheet due to warping of the sheet.

Therefore, in the copying machine of this embodiment, for example, when three (three color) images are to be superimposed, the copying process is started after operating the key KO and setting the paper feeding mode (register Rfix) to 3. do. In this case, in the first image reproduction, the fixing process is performed with the fixing temperature set to a considerably low value. In this case, although the fixability of the image is unfavorable, since the sheet is less likely to warp, the occurrence of wrinkles on the sheet is prevented in the second and subsequent image reproductions.

When the first image reproduction process and fixing process are completed, the contents of the register Rfix are decremented to 2. Therefore, in the next second image reproduction process, the fixing temperature is lower than normal, but higher than the first time. The fixing process is performed with the value set to a large value. In this case, the fixability of the image reproduced in the second process is slightly inferior to the proper state, but since the warping caused on the sheet by the second fixing process is relatively small,
In the third image reproduction, wrinkles are prevented from forming on the sheet. Also, by the second fixing process, the first
Since the reproduced image is also fixed in the second processing, the fixability of the image is improved compared to the first processing.

When the second image reproduction process and fixing process are completed, the contents of the register Rfix are decremented to 1 again, so in the next third image reproduction process, the fixing temperature is set to the normal state. Fixing processing is performed at ty. In the third fixing process, together with the image reproduced in the third process, the images reproduced in the first and second processes are again subjected to the fixing process, so the third process ends. Then, sufficient fixability can be obtained for the images reproduced in the first and second processing. Moreover, since the warping of the sheet after the second processing is completed is kept relatively small, there is little possibility that wrinkles will occur in the sheets 1 to 1 in the third processing.

In this type of copying machine, the power to the copying machine is often automatically cut off when replacing one color from 1 to 4 of the developing device.
In this example, the contents of register Rfix are non-volatile R
Since it is connected to the AM280, the contents of Rfix will not be destroyed even if the toner color is changed.

In addition, when creating double-sided copies manually, by operating the KO key and setting the paper feeding mode to 2, copies can be made without wrinkles on the sheets, as in the case of the above process. can be created.

The contents of the "double-sided A mode" process shown in FIG.
As shown in the figure. In this process, first, the document is positioned at a predetermined position on the contact glass 1 and the copy number counter N copy is cleared to O. Next, the contents of the copy number counter Ncopy are set to the copy number register N set.
, compared with the contents of .

If N copy < N set, execute the following process. First, the state of the flag F5ide is checked. Note that this flag F 5ide is reset to rr O++ in the case of copying the first side (front side), and is set to u 1 +1 in the case of copying the second side (back side).

If F 5ide is tg Ou, the cassette (first
Paper is fed from one of the paper feed systems to the fifth paper feed system selected from the paper feed system to the fifth paper feed system, and a known copying process is executed.

When the copying process is completed, the copy sheet is ejected to the intermediate tray in the duplex processing device 80 and placed on the copy counter N.
The contents of copy are incremented by 1 and the process returns to step D1.

When the state of the flag F5ide is '1'', the double-sided processing bag ri1180 is controlled to feed the sheet on the intermediate tray and perform a known copying process.

The sheet is fed from the duplex processing device 80 because the direction in which the sheet is conveyed is opposite to the direction in which the sheet is fed from the intermediate tray in the duplex processing device 80. The state of the sheet at the time is reversed with respect to the state when it is fed from the cassette. Therefore, when a sheet is fed from the duplex processing device 80,
An image is recorded on the second side (back side) of the sheet. When the copy process is completed, the paper ejection path is switched, the copy sheet is ejected to the sorter 70, the copy counter N copy is incremented, and the process returns to step DI.

When N copy = N scL in step D1, the operation mode of the document conveyance device 60 is checked. If the mode is 80F, the presence or absence of a document on the document conveyance device 60 is further checked. If a manuscript exists.

Invert the state of flag Fside ('1' if 'o')
111 II), transports a new document and positions it on the contact glass 1, and clears the contents of the copy counter Neopy to 0.Furthermore, if the flag F5ide is It OII, Store fixed value T1 in register TMP, Fside is 11
In the case of 177, T2 is stored and the copy operation is repeated.

When Ncopy=Ns is reached in step D1, if the document transport device 60 is not in the ADF mode or if there is no document to be sent next, the process ends. In this case, the state of the flag F5ide is checked and it is rr On.
In this case, since there is a sheet left on the intermediate tray, it is discharged to the sorter 70 side.

Note that the fixed value T2 stored in the register TMP is a value corresponding to the heater temperature of the fixing device in a normal copying operation, and the fixed value T1 corresponds to a fixing temperature lower than T2.

Therefore, when performing double-sided copy processing, the first side (front side)
When copying, the target temperature of the fixing device 2 is set lower than usual. In this case, the fixability of the image transferred to the first side of sheet 1- is inferior to normal, but when this sheet undergoes the second process, the image on the first side undergoes the fixing process again, so When the processing of the second side is completed, the image on the first side also has a good fixing property.

Also, when the fuser is set to the normal fusing temperature,
Although relatively large warpage often occurs in the sheet that passes through it, in this example, since the fixing temperature is low at the stage where the first side is processed in the double-sided copy mode, the warp that occurs in the sheet is small. Therefore, wrinkles are prevented from forming on the sheet when processing the second side.

The contents of the ``Double-sided B mode'' process shown in Figure 5.

Shown in Figure 6d. In this process, first, the original is positioned at a predetermined position on the contact glass I, and the copy counter N copy is cleared to O. Next, the contents of the copy number counter Ncopy are compared with the contents of the copy number register N5et.

If N copy < N set, perform the primary processing. first.

Check the state of flag F5ide.

If the flag F5ide is 0'', paper is fed from the cassette and a known copying process is executed. When the copying process is completed, the copy sheet is ejected to the intermediate tray in the duplex processing device 80, and the copy counter Ncopy is set. The contents are incremented and the process returns to step E1.

When flag F5ide is II 1'H, double-sided processing bag F! 80 to control the sea 1- on the middle 1-ray.
feed the paper and perform the copy process. When the copy process is completed, the paper ejection path is switched, the copy sheet is ejected to the sorter 70, the copy counter N copy is incremented, and the process returns to step E1.

When Neoρy = N set in step E1, the operation mode of the document transport device e160 is checked. A
If it is the DF mode, the presence or absence of an original on the original transport device 60 is further checked. If a document exists, a new document is transported and positioned on the contact glass 1, the content of the copy counter Ncopy is cleared to 0, and the copy operation in step 118 is repeatedly executed.

When N copy = N set in step E1, if the operation mode of the document feeder 60 is not the ADF mode, or if there is no document to be sent next, the flag F is set.
Invert the state of 5ide and check the result.

When F 5ide is tt 1 u, a fixed value T2 is stored in register TMP. Then, wait until the key switch KS is turned on.

The double-sided B copy mode is an operation mode for making double-sided copies from a document with images on both sides.

Therefore, in this operation mode, the copying operation and paper feeding operation from the cassette are repeated for the first side of all originals,
Copy sheets with an image transferred only on the first side are stored in the intermediate tray of the duplex processing device 80.

When processing of the first side is completed and processing of the second side is started,
Once the document group has been ejected, it is turned over and transferred to the document conveying device 60 again.
Since it is necessary to set the copying machine to 1, stop the operation of the copying machine and press the key switch KS.

When the key switch KS is turned on, the operation mode of the document feeder 60 is checked, and if it is ADF mode,
Furthermore, check whether there is a manuscript. If a new original is set, one original is transported and positioned on the contact glass 1, and the copy counter N copy
Clear the contents to 0 and repeat the copy operation.

If the flag F5ide is '1'' in step E2.

Ends processing and returns to standby processing.

In other words, in this copying machine, in both duplex A copy mode and duplex B copy mode, when processing the first side of a sheet, the target temperature of the fuser is automatically set lower than normal. .

Therefore, even when double-sided copying is performed, wrinkles do not occur on the sheet.

Temperature control of the fixing heater HT is handled by an interrupt process that is periodically executed by a timer interrupt. This process is shown in Figure 6e.

See Figure 6e. In this process, first, the output signal of the thermistor Tl+ is sampled by the Δ/D converter 260 to obtain voltage data ot-h.

Next, the thermistor temperature "1th" is determined from the data Djh. The thermistor temperature "I't,h" is then compared with the target temperature, and the energization of the heater HT is controlled according to the result.

That is, if Tth>TMP+ΔT, the signal HTON is set to a high level it (off level) to cut off the heater current, and if Tth<TMP−ΔT, the HTON is set to a low level L.
(on level) and start energizing the heater.

Therefore, the actual temperature of the fixing device shows changes as shown in FIG. The average value of this temperature is [1 standard temperature register T
It is changed according to the contents of MP.

Note that the operation for switching the target temperature of the fixing device may be changed so that it is performed during standby processing of the copying machine.

[Effects] As described above, according to the present invention, even when the fixing process is performed multiple times on one sheet.

This prevents wrinkles from forming on the sheet.

[Brief explanation of drawings]

FIG. 1 is a front view showing the external appearance of a mechanical part of one type of copying machine embodying the present invention. FIG. 2 is an enlarged view showing the fixing device 12 of the copying machine shown in FIG. 3 is a plan view showing the appearance of the operation board of the copying machine shown in FIG. 1. FIG. FIG. 4a is a block diagram showing the configuration of the electrical equipment of the copying machine shown in FIG. 1, and FIG. 4b is the heater control board 340 shown in FIG. 4a.
FIG. FIG. 5 is a flowchart showing an outline of the operation of the main controller 200 shown in FIG. 4a. 6a, 6b, 6c, 6d, and 6e are flowcharts showing details of a portion of the process shown in FIG. 5. FIG. 7 is a graph showing an example of a change in the fixing temperature of the copying machine shown in FIG. 1: Contact glass 2: Photosensitive drum (recording means) 3: Main charger 5: IJI imager 7: Transfer charger 8: Separation charger 12: Fixing device (fixing means) 12a: Fixing roller 12b: Pressure roller 12c
: Fixing device 12f: Pressure force 1121-24:
Paper feed cassette 25: Paper feed tray 30: Optical scanning system 60: Original transport device 70: Sorter 80: Double-sided processing device 200: Main controller (electronic control means) 310: Operation board KO, 7: Key (paper feeding mode) switching means) M l :
? ! ! Motor HT: Heater (heating means)

Claims (3)

[Claims] (1) A recording device that records an image on the surface of a predetermined sheet; A fixing device that is disposed downstream of the recording device in the conveyance path of the sheet and performs an image fixing process on the sheet; Heat that is heated by the fixing device means; paper passing mode switching means for setting a paper passing mode set according to the number of times the sheet passes through the fixing means; and controlling the temperature of the heating means, and setting a target temperature for the control;
A fixing device for a recording device, comprising: an electronic control unit that automatically switches the paper passing mode according to the paper passing mode set by the paper passing mode switching unit. (2) The electronic control means sets the target temperature of the heating means in the first sheet fixing process lower than the target temperature in the second sheet fixing process, according to claim (1). Fixing device for recording equipment. (3) The recording means includes a sheet reversing means for reversing the front and back sides of the sheet, and the electronic control means controls the target temperature of the heating means when the sheet feeding mode is set to the double-sided processing mode. After the sheet is passed through the recording means and the fixing means, the target temperature of the heating means is set to a second temperature higher than the first temperature, and the sheet is turned over. A fixing device for a recording device according to claim (2), wherein the sheet is passed through the recording device and the fixing device again to be discharged.