JPH06110354A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To obtain a good required copied image in any kind of a copying mode by adjusting the temperature of a fixing part for 2 full color copying mode in the case of detecting that a sheet is a cardboard, and in the case of setting in a synthetic copying mode before copying is performed. CONSTITUTION:When the sheet is detected to be the cardboard(cardboard detecting mechanism 300), the temperature adjusting(S9) of the fixing part for the full color copying mode is priorly performed regardless of the copying mode, and the fixing is performed at the fixing part. That is, since the temperature of the fixing part for the full color copying mode is higher than that for a black-and-white copying mode, enough quantity of heat for melting and fixing the toner image formed on the cardboard can be given. When the synthetic copying mode is set(S1), the temperature adjusting of the fixing part for the full color copying mode is performed preferentially (S8) in whichever case an original is black-and-white or colored, and also the fixing is performed by using the fixing part for the full color copying mode (S10).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus having a plurality of copy modes.

[0002]

2. Description of the Related Art Some copying machines as an electrophotographic apparatus are capable of executing a plurality of copying modes such as a black-and-white copying mode and a full-color copying mode. In order to obtain the required copy image, it is necessary to provide a fixing unit for each copy mode so that the toner image transferred onto the sheet can be fixed reliably.

An example of such a copying machine is Japanese Patent Laid-Open No. 51-9.
No. 8036 discloses that a fixing device has three types of upper, middle and lower parts.
A single heat roller is provided, a first fixing unit is formed between the upper and middle heat rollers, and a second fixing unit is formed between the middle and lower heat rollers, and the sheet is conveyed to these first and second fixing units. It has been proposed to move the sheet conveying device according to the fixing unit used.

In such a copying machine, when the first fixing unit is the fixing unit for the full-color copy mode and the second fixing unit is the fixing unit for the monochrome copy mode, the first fixing unit is formed on the sheet. Since the toner image has a plurality of layers, it needs to be heated to a high temperature. On the other hand, since the toner image formed on the sheet has a single layer, the second fixing unit does not need to have a temperature as high as that of the first fixing unit. For example, the upper heat roller is 210 ℃
The middle heat roller to 190 ° C and the lower heat roller to 1
Since each heat roller can be appropriately heated depending on the fixing unit used, such as heating to 30 ° C., toner fixing in each copy mode can be reliably performed, and a copy image required for each can be obtained. it can.

Further, some of the copying machines capable of executing a plurality of copy modes as described above have a composite copy mode for combining a plurality of different originals on the same sheet and copying in addition to a monochrome copy mode and a full color copy mode. Some of them are equipped with an oil application device for applying oil to the surface of the heat roller so that the sheet after fixing is easily separated from the heat roller in the fixing section.

[0006]

In the above copying machine, generally, if the thickness of the sheet is thin and constant, the toner image is appropriately fixed in each copy mode to obtain the copy image required for each. be able to.

However, when the sheet is thick, that is, when a thick paper such as a postcard is used as the sheet, in order to completely melt and fix the toner image transferred to the thick paper, a sheet having a normal thickness is used as compared with the case where the sheet having a normal thickness is used. Need to be fixed at high temperature. At this time, in the full-color copy mode, since the fixing unit for the full-color copy mode, which has a high temperature, is used, the melting of the toner image is sufficient, and the required copy image can be obtained without any problem. In the copy mode, since the fixing unit for the black and white copy mode, which has a low temperature, is used, the toner image is not sufficiently melted,
There is a problem that fixing failure occurs and a required copy image cannot be obtained.

Similarly, when a copy is executed in the composite copy mode, a plurality of originals are composited, so that the toner image formed has a plurality of layers, and the transferred toner image is completely formed as in the case where the sheet is thick paper. In order to fuse and fix, it is necessary to fix at high temperature. Therefore, when a composite copy is performed with a black-and-white original, the fixing unit for the black-and-white copy mode having a low temperature is used, so that the toner image is not sufficiently melted and fixing failure occurs to obtain the required copy image. There is a problem that you cannot do it.

Further, in the electrophotographic apparatus provided with an oil application device for applying silicon oil (hereinafter simply referred to as oil) to the surface of the heat roller so that the sheet after fixing at the fixing portion can be easily separated from the heat roller, For example, when performing a full-color copy, oil is applied to the heat roller, so the sheet after fixing is easily peeled from the heat roller, and fixing is performed accurately to obtain the required copy image. be able to. However,
In black-and-white copying, the toner image that is formed is usually a single layer, and the fixed sheet easily peels from the heat roller even if oil is not applied to the heat roller due to the characteristics of black toner. When the fixing is performed by the heat roller to which the oil is applied, the oil applied to the heat roller is wasted and the oil consumption increases.

Further, the surface of the heat roller is usually cleaned by a cleaning roller provided in pressure contact with the heat roller, for example. Therefore, as described above, since the useless oil applied on the heat roller must be constantly removed, the cleaning roller is significantly deteriorated, and as a result, the heat roller surface is not sufficiently cleaned, and fixing is performed. There is a problem that defects are likely to occur and a required copy image cannot be obtained.

The present invention has been made in view of the above problems, and an object of the present invention is to make a copy when a copy is performed by using a thick paper or the like for a sheet and when a copy is performed in a composite copy mode. A desired good copy image can be obtained regardless of the mode, and further, the oil application amount can be adjusted according to the copy mode to eliminate fixing failure and obtain a desired good copy image. An object is to provide an electrophotographic apparatus.

[0012]

An electrophotographic apparatus according to claim 1 has a fixing unit for a monochrome copy mode and a fixing unit for a full color copy mode, and a plurality of originals are copied on the same sheet. In an electrophotographic apparatus having a setting means for setting the composite copy mode, the thick paper detecting means for detecting that the sheet is thick paper is provided, and when the thick paper detecting means detects that the sheet is thick paper, and When the composite copy mode is set before execution, a fixing mechanism control unit is provided for adjusting the temperature of the fixing unit for the full color copy mode and controlling the fixing mechanism so that the fixing unit performs fixing. It is characterized by that.

According to a second aspect of the present invention, there is provided the electrophotographic apparatus according to the first aspect.
The electrophotographic apparatus described above is characterized by further comprising oil application amount control means for controlling the amount of oil applied to the fixing unit for the full-color copy mode.

[0014]

According to the structure of claim 1, when the sheet used by the fixing mechanism control means is thick paper, the temperature of the fixing portion for the full color copy mode is adjusted regardless of whether the original is black and white or color and the full color copy is performed. Since the fixing mechanism is controlled so that fixing is performed by the fixing unit for the mode, it is always possible to apply sufficient heat to melt the toner image formed on the cardboard sheet, and it is required without causing fixing failure. You can get a copy image. Further, even when a plurality of layers of toner images are formed on the same sheet as in the composite copy mode, the temperature of the fixing unit for the full color copy mode can be adjusted and the fixing can be performed in this fixing unit. Therefore, it is possible to always give sufficient heat to melt the toner images of a plurality of layers, and the required copy image can be obtained without causing fixing failure.

According to the second aspect of the invention, the oil application amount control means controls the oil application amount to be smaller than the oil application amount in the case of full-color copy when the sheet is thick paper and black-and-white copy is made. This makes it possible to reduce the amount of oil applied when thick paper is used for black-and-white copying, and it is possible to efficiently apply oil to the fixing section. Therefore, waste of oil consumption can be reduced. From this, it is possible to suppress deterioration of, for example, a cleaning roller or the like for removing useless oil applied to the fixing unit, and it is possible to always perform sufficient cleaning of the fixing unit. Fixing failure can be reduced, and a required copy image can be obtained.

[0016]

【Example】

[Embodiment 1] One embodiment of the present invention is shown in FIGS.
The explanation is based on the following.

A full-color copying machine (hereinafter simply referred to as a copying machine) as an electrophotographic apparatus in this embodiment is shown in FIG.
As shown in FIG. 2, the copying machine main body 1 and an inversion retransmission unit (not shown) as an inversion retransmission device provided under the copying machine main body 1 are provided.

Further, the main body 1 of the copying machine has an original placing table 3 made of hard transparent glass on the upper surface thereof, and an exposure optical system section 4 under the original placing table 3. The exposure optical system unit 4 includes a lamp unit 5 that scans an original (not shown) placed on the original placing table 3 while irradiating the original with light.
A plurality of reflecting mirrors 6 that guide the reflected light from the document to the photoconductor 8 ...
And the lens unit 7 arranged in the optical path of the reflected light.
And have.

A charging charger 9 for charging the surface of the photoconductor 8 to a predetermined potential is provided on the outer periphery of the photoconductor 8, and the charging charger 9 further rotates the photoconductor 8 in the direction of arrow B. Toward the image-to-image eraser (not shown), the black developing tank 10, the yellow developing tank 11,
A magenta developing tank 12, a cyan developing tank 13, an intermediate transfer device 14, a cleaning device 15, and a charge eliminating device 16 are arranged in this order.

The intermediate transfer device 14 is the transfer belt 1
7. Rollers 18, 19 supporting this transfer belt 17
20, the transfer belt 17 is pressed against the photosensitive member 8
The first transfer roller 21 that transfers the toner image formed on the surface to the transfer belt 17, and the second transfer roller that is pressed against the roller 20 when the toner image is transferred to the paper and transfers the toner image on the surface of the transfer belt 17 to the paper. A roller 22 and a cleaning device 23 that removes residual toner on the surface of the transfer belt 17 are provided.

On the paper feed side of the above-mentioned intermediate transfer device 14, a sheet of paper is transferred at a predetermined timing.
A registration roller 24 for supplying a sheet to a sheet, a sheet feeding cassette 25 as a sheet feeding unit, and a sheet feeding tray 26 are provided. Near the sheet feeding cassette 25 and the sheet feeding tray 26,
Paper feed rollers 27, 27, a transport roller 28, and the like are provided. Further, on the paper output side of the paper feed tray 26,
A thick paper detection mechanism 300 that detects that the paper is thick paper is provided.

As shown in FIG. 3, the thick paper detecting mechanism 300 is provided in the vicinity of the carrying roller 28 on the upper paper guide 304 forming the paper carrying path 306, and has an actuator lever 310a which comes into contact with the paper. An actuator 310 including a small lever 310b provided on the opposite side of the actuator lever 310a via the support shaft 303, and a large lever 310c provided on the actuator lever 310a and the support shaft 303, and a detection signal for thick paper. For transmitting information, for example, photo sensor 30
1 and.

The actuator lever 310a of the actuator 310 is provided so as to project from the upper paper guide 304 to the paper transport path 306 so as to come into contact with the paper, and a slight gap is provided between the lower paper guide 305 and the lower paper guide 305. It has become. Further, the actuator lever 310a is rotatably supported by the support shaft 303, and when the paper conveyed to the paper conveyance path 306 is a thick paper such as a postcard, the paper is easily deformed, that is, the stiffness is strong. It is rotated so as to be pushed up above the upper paper guide 304, but is not rotated when the conveyed paper is not thick paper, for example, if it is a weak sheet such as a copy sheet that is normally used. Has become. Further, the small lever 310b is supported by the spring 302 so as to return to the original position when the actuator lever 310a is rotated upward by the thick paper, and the rotation force due to the strength of the aforementioned stiffness can be adjusted. , Usually the actuator lever 310a is the upper paper guide 30
4 is projected to the paper transport path 306, that is, the lower position.

The large lever 310c is designed to block the light beam emitted from the photosensor 301 when the actuator lever 310a is normally in the lower position. When turned to, the light beam from the photosensor 301 is transmitted to a light receiver (not shown). Further, control for thick paper is performed based on the detection signal of the photo sensor 301 at this time.

Although the photo sensor is used as the thick paper detection sensor in the above, the invention is not limited to this.

On the other hand, in the paper output direction from the intermediate transfer device 14, as shown in FIG. 2, the suction unit 100 as a sheet transfer device for transferring the paper, the fixing device 200,
Switching gate 29, paper ejection roller 30, and paper ejection tray 3
1 is provided. The switching gate 29 is configured to switch the conveying direction of the sheet discharged from the fixing device 200 between the discharge roller 30 direction and the lower conveying path 32 direction. The conveying path 32 is not shown in the figure. The transport unit is provided to transport the paper.

The suction unit 100 described above uses a moving conveyor belt (not shown) to fix the sheet on the fixing device 2.
It is to be transported to 00, and the end portion on the paper input side is pivotally supported,
It is adapted to move up and down between an upper position and a lower position.
The upper position is a position for transporting a sheet to an upper fixing portion of the fixing device 200 described later, and the lower position is a position for transporting a sheet to a lower fixing portion of the fixing device 200. The vertical movement of the suction unit 100 is performed by, for example, a cam mechanism provided on the lower surface side of the suction unit 100, a solenoid, or the like.

Further, as shown in FIG. 4, the fixing device 200 is provided with an upper heat roller 201, a middle heat roller 202 as a separating / contacting heat roller, and a lower heat roller 203, which are vertically parallel to each other. ing. The upper heat roller 201 and the middle heat roller 202, and the middle heat roller 202 and the lower heat roller 203 are pressed against each other,
The upper fixing portion formed at the pressure contact portion between the upper heat roller 201 and the middle heat roller 202 serves as a fixing portion at the time of full color copying, and the middle heat roller 202 and the lower heat roller 20.
The lower fixing portion formed in the pressure contact portion with 3 is a fixing portion for black-and-white copying. Therefore, an appropriate material is used for each of the surface layers, and the upper heat roller 201 has a very smooth surface in order to obtain high releasability from the three-layer toner image for obtaining a full-color image. The silicone rubber, the middle heat roller 202 is excellent in durability and is economical Teflon, and the lower heat roller 203 is made of silicone rubber or other suitable rubber.

Further, each of the heat rollers 201 to 203 is hollow, and the heater lamp 20 for heating is provided in this hollow portion.
4a-d are respectively provided. In the present embodiment, the power consumption of each of the heater lamps 204a to 204d is, for example, 650w for the heater lamp 204a and the heater lamp 20.
4b is 350w, heater lamp 204c is 300w, and heater lamp 204d is 350w. In addition, around the upper and lower heat rollers 201 to 203, the thermistor 205 for detecting the surface temperature and the heater lamp 20.
Thermostats (not shown) for preventing overheating incorporated in the circuits 4a to 4d, and heat rollers 201 to 203
A cleaning roller 206 for removing the toner and the like adhering to the surface of the is provided. Further, around the middle and lower heat rollers 202 and 203, peeling claws 207 for peeling the paper from the roller surface are provided, while around the upper heat roller 201, for example, silicon oil (hereinafter,
An oil application roller 208 impregnated with (hereinafter simply referred to as oil) is provided. This oil application roller 208
Is for applying oil to the surface of the upper heat roller 201 to prevent adhesion of the color toner to the surface of the heat roller, that is, offset, to ensure the peelability of the color toner image and to impart gloss to the full-color copy image. belongs to. Further, the oil applying roller 208 is provided on the support shaft 20.
The upper fixing portion is used by a mechanism that is attached to one end of a roller holder 210 that rotates around 9 and that is provided at the other end of the roller holder 210 and that includes an eccentric cam 211 and a tension spring (not shown). At times, the upper heat roller 201 is brought into pressure contact with the upper heat roller 201. The eccentric cam 211 is driven by an oil application roller cam drive mechanism (not shown).

In order to form the upper fixing portion and the lower fixing portion, the middle heat roller 20 is used in this embodiment.
A mechanism is employed in which the upper and lower heat rollers 201 and 203 are brought into contact with and separated from each other by moving 2 up and down.

An upper discharge conveyance path 41 is formed between the upper fixing section and the sheet discharge roller 30, and a lower discharge conveyance path 42 is formed between the lower fixing section and the sheet discharge roller 30. ing. From this lower discharge conveyance path 42, the retransmission conveyance path 32 branches and extends downward, and at the branching portions of these both conveyance paths 42, 32, the paper was discharged from the lower fixing section to the lower discharge conveyance path 42. The paper conveyance direction is set to the discharge roller 30 side and the retransmission conveyance path 32.
A switching gate 29 for switching between the side and the side is provided.

When the original is black and white and the sheet is thick paper, the above-mentioned sheet for full-color copying is set by the fixing mechanism control section (fixing mechanism control means) 51 including S4, S5 and S9 shown in FIG. The suction unit 100 is moved upward and the upper heat roller 201 and the middle heat roller 202 are controlled to be heated to a predetermined temperature so that the fixing unit can perform fixing.

In the above arrangement, first, the full-color copy operation of this copying machine will be described. When the copy start button (not shown) is turned on after the full color copy selection key (not shown) is turned on, the middle heat roller 202 moves to the upper heat roller 201 side to form a pressure contact portion, and The upper heat roller 201 rotates counterclockwise, and the upper heat roller 201 rotates clockwise accordingly. Further, the oil applying roller 208 is the upper heat roller 2
01, and the suction unit 100 moves so as to be held in the upper position.

At this time, the heater lamp 204a of the upper heat roller is turned on so that the roller surface has a predetermined temperature, that is, 21
The temperature is raised to 0 ° C., and the medium heat roller 202 2
Of the two heater lamps 204b and 204c, only the heater lamp 204b is turned on to raise the temperature of the roller surface to a predetermined temperature, that is, 190 ° C.

Further, the surface of the photoconductor 8 rotating in the B direction is uniformly charged by the charging charger 9, and the exposure optical system section 4 scans the original on the original placing table 3 for the first time. At this time, the reflected light from the document passes through the blue color separation filter (not shown) and the slit (not shown), and the charger 9 and the inter-image eraser (not shown).
And the exposure point on the surface of the photoconductor 8 is irradiated, and the photoconductor 8 is exposed to form an electrostatic latent image. Next, the potential of the non-image area on the photoconductor 8 is removed by the inter-image eraser, and then the electrostatic latent image is developed by the yellow developing tank 11 to form a yellow toner image.

Next, the yellow toner image on the surface of the photosensitive member 8 is the first transfer roller 21 to which a negative high voltage is applied.
Is transferred to the transfer belt 17 which moves in the C direction. The residual toner on the surface of the photoconductor 8 is removed by the cleaning device 15, and the residual potential on the surface of the photoconductor 8 is removed by the charge eliminating device 16.

When the above series of operations is completed, the photoconductor 8 is charged again by the charging charger 9, and the document is scanned by the exposure optical system section 2 for the second time. In this case, a green color separation filter is used, and the electrostatic latent image formed on the photoconductor 8 is developed by the magenta toner in the magenta developing tank 12. The magenta toner image thus formed on the surface of the photoconductor 8 is transferred by the first transfer roller 21 so as to be superimposed on the previous yellow toner image on the transfer belt 17. After that, in the same way,
The third scanning is performed by the exposure optical system unit 4 using the red color separation filter, and the cyan toner image in the photoconductor 8 is formed by the development with the cyan toner in the cyan developing tank 13. This cyan toner image is transferred onto the preceding yellow toner image and magenta toner image on the transfer belt 17.

Next, the second transfer roller 22, which has been separated from the transfer belt 17 in the operation so far, is transferred to the transfer belt 1.
When the sheet is pressed against 7 and a negative voltage higher than the surface potential of the transfer belt 17 is applied to the second transfer roller 22, the sheet is conveyed from the sheet feeding cassette 25 or the sheet feeding tray 26 through the registration roller 24. The three-layer toner image on the transfer belt 17 is transferred onto the paper.

The above-mentioned paper on which the toner image is transferred is conveyed by the suction unit 100 to the upper fixing portion formed at the pressure contact portion between the upper heat roller 201 and the middle heat roller 202. In the upper fixing unit, the three-layer color toner images on the paper are transferred to the upper and middle heat rollers 201 and 202.
It is heated and melted by and is fixed on the paper. At this time, the oil coating roller 208 is attached to the upper heat roller 201.
Since the silicone oil is supplied from the above, the offset of the toner image on the upper heat roller 201 is prevented, and gloss is imparted to the full-color toner image on the paper.

Next, the paper ejected from the fixing device 200 is ejected onto the paper ejection tray 31 by the paper ejection roller 30.

Next, the black and white copying operation of this copying machine will be described. When the copy start button is turned on after the black-and-white copy selection key (not shown) is turned on from the above-mentioned full-color copy enabled state, the middle heat roller 20
2 moves to the lower heat roller 203 side to form a pressure contact portion, and rotates in the clockwise direction, and accordingly, the lower heat roller 203 rotates in the counterclockwise direction. Further, the suction unit 100 is moved so as to be held in the lower position, and the oil applying roller 208 is moved to the upper heat roller 20.
Away from 1.

At this time, the two heater lamps 204b and 204c of the middle heat roller 202 are both turned on to raise the temperature of the roller surface to a predetermined temperature, that is, 190 ° C., and the heater lamp 204d of the lower heat roller is turned on. The temperature of the roller surface is raised to a predetermined temperature, that is, 130 ° C.

The surface of the photoconductor 8 is charged by the charger 9.
Are uniformly charged, and the exposure optical system unit 4 scans the document on the document table 3. The reflected light from the document is guided to the exposure optical system unit 4 and irradiates the exposure point of the photoconductor 8 without passing through the color separation filter and the slit, and an electrostatic latent image is formed on the photoconductor 8. Then, the electrostatic latent image is developed by the black developing tank 10, and the black toner image formed by the development is transferred to the transfer belt 1.
After being transferred to the sheet 7, it is further transferred to the sheet from the transfer belt 17.

The above-mentioned sheet on which the toner image is transferred is conveyed by the suction unit 100 to the lower fixing section formed at the pressure contact portion between the middle heat roller 202 and the lower heat roller 203, and the toner image is formed on the sheet. Fixed on top.

Here, in the case of one-sided copying, the fixing device 2
The sheet discharged from the lower fixing unit of 00 to the lower discharge conveyance path 42 is guided to the discharge roller 30 by the switching gate 29,
Then, the paper is discharged onto the paper discharge tray 31.

On the other hand, in the case of double-sided copying, the fixing device 20
The sheet discharged from the lower fixing unit 0 to the lower discharge conveyance path 42 is guided to the retransmission conveyance path 32 by the switching gate 29, then carried into the retransmission reversing device, and placed on the intermediate tray (not shown). After that, it is sent to the conveyance path 35, inverted here, and conveyed to the registration rollers 24.

Next, the surface of the photoconductor 8 is charged by the charger 9.
Then, the exposure optical system section 4 scans the original placed on the original placing table 3 with the exposure optical system section 4 turned upside down.
Next, the toner image is transferred to the back surface of the sheet by the same operation as described above, and the toner image is fixed on the sheet in the lower fixing unit. Thereafter, this sheet is guided to the sheet discharge roller 30 by the switching gate 29, and the sheet discharge tray 31.
Discharged on top.

On the other hand, in the copying machine having the above-mentioned structure, a copy in the case of using a paper thicker than a paper thickness normally used for the paper will be described below with reference to FIG.

When the paper 50 placed on the paper feed tray 26, which is a manual paper feed unit, is ejected by the paper feed rollers 27, 27, the paper conveyance path 3 is conveyed by the conveyance rollers 28, 28.
It is transported to 06. At this time, the actuator lever 310a is pushed up by the sheet 50, and the actuator is rotated as shown by the broken line in FIG. 3, whereby the large lever 310c moves upward and transmits the light beam of the photosensor 301. At this time, the conveyed paper 50 is detected as the thick paper 50b, this detection signal is sent to a control device (not shown), and a copy of the thick paper 50b will be described later.
It is performed based on the control of the flowchart shown in FIG.

On the other hand, the paper 50 is the actuator lever 3
When it comes into contact with 10a, this actuator lever 31
If 0a is not pushed up, it is judged that the paper 50 is not the thick paper 50b but the normal paper 50a, and the processing based on each copy mode is performed.

Further, a composite copy in which a plurality of different originals are copied on the same sheet in the copying machine having the above-mentioned structure will be described below with reference to FIG.

First, after the composite copy selection key (not shown) is turned on, the copy start button (not shown) is turned on.
When it is N, the middle heat roller 202 is the upper heat roller 2
While moving to the 01 side to form a pressure contact portion, the middle heat roller 202 rotates counterclockwise, and the upper heat roller 201 rotates clockwise accordingly. Also,
The oil application roller 208 is pressed against the upper heat roller 201, and the suction unit 100 moves so as to be held at the upper position.

At this time, the heater lamp 204a of the upper heat roller is turned on so that the roller surface has a predetermined temperature, that is, 21
The temperature is raised to 0 ° C., and the medium heat roller 202 2
Of the two heater lamps 204b and 204c, only the heater lamp 204b is turned on to raise the temperature of the roller surface to a predetermined temperature, that is, 190 ° C.

Further, the surface of the photoconductor 8 rotating in the B direction is uniformly charged by the charging charger 9, and the exposure optical system unit 4 scans the first document on the document table 3 for the first time. . The light reflected from the original document is applied to the exposure point on the surface of the photoconductor 8 between the charger 9 and the inter-image eraser (not shown), and the photoconductor 8 is exposed to form an electrostatic latent image. Next, the potential of the non-image area on the photoconductor 8 is removed by the inter-image eraser, and then the electrostatic latent image is developed by the black developing tank 10 to form a black toner image.

Next, the black toner image on the surface of the photoconductor 8 is the first transfer roller 21 to which a negative high voltage is applied.
Is transferred to the transfer belt 17 which moves in the C direction. The residual toner on the surface of the photoconductor 8 is removed by the cleaning device 15, and the residual potential on the surface of the photoconductor 8 is removed by the charge eliminating device 16.

When the above-described series of operations is completed, the photoconductor 8 is charged again by the charging charger 9, and the exposure optical system unit 4 scans the second original, and the photoconductor 8 is scanned.
An electrostatic latent image is formed on. Then, the electrostatic latent image is developed with the black toner in the black developing tank 10 again. The black toner image on the surface of the photoconductor 8 thus formed is transferred by the first transfer roller 21 onto the previous black toner image on the transfer belt 17 in an overlapping manner. The above operation is performed for the required number of documents.

Next, the second transfer roller 22 separated from the transfer belt 17 in the operation so far is transferred to the transfer belt 1.
When the sheet is pressed against 7 and a negative voltage higher than the surface potential of the transfer belt 17 is applied to the second transfer roller 22, the sheet is conveyed from the sheet feeding cassette 25 or the sheet feeding tray 26 through the registration roller 24. The toner images of a plurality of layers on the transfer belt 17 are transferred onto the paper.

The above-mentioned paper on which the toner image is transferred is conveyed by the suction unit 100 to the upper fixing portion formed at the pressure contact portion between the upper heat roller 201 and the middle heat roller 202. In the upper fixing unit, the toner images of a plurality of layers on the sheet are heated and melted by the upper and middle heat rollers 201 and 202 and fixed on the sheet. At this time,
Since silicon oil is supplied to the upper heat roller 201 from the oil applying roller 208, the toner image on the upper heat roller 201 is prevented from being offset and the toner image on the paper is provided with gloss.

Next, the paper discharged from the fixing device 200 is discharged onto the paper discharge tray 31 by the paper discharge roller 30.

Here, the control of the above-mentioned fixing mechanism will be described below with reference to the flow chart shown in FIG.

First, it is determined whether the composite copy mode is set (S1). If the composite copy mode is not set, it is determined whether the monochrome copy mode or the full color copy mode is executed (S2). Then, if the monochrome copy mode is executed, it is detected whether or not the paper to be copied is thick paper (S3). If it is detected that the paper is thick paper, the position of the suction unit is for the full-color copy mode as in the case where the composite copy mode is set in S1 and the full-color copy mode is executed in S2. (S4), and if it is not on the fixing section side for the full color copy mode, the suction unit is moved to the fixing section side for the full color copy mode (S5). If the position is on the fixing portion side for the full color copy mode, the temperature of the fixing portion for the full color copy mode is adjusted (S9). Then, after fixing is performed in the fixing unit for the full-color copy mode, the sheet is discharged to the discharge tray (S10).

On the other hand, if it is detected in S3 that the paper is not thick paper, it is determined whether or not the position of the suction unit is on the fixing section side for the black and white copy mode (S6), and if the fixing for the black and white copy mode is performed. If not, move the suction unit to the fixing unit side for black and white copy mode (S
7). Then, it is determined whether or not the temperature adjustment of the fixing unit for the black and white copy mode is set to be performed with priority (S8), and the temperature adjustment of the fixing unit for the black and white copy mode is performed with priority. If it is set to, the fixing unit for black and white copy mode is fixed as it is and discharged to the discharge tray (S10), but the temperature of the fixing unit for black and white copy mode is set to be preferentially adjusted. If not, since the temperature of the fixing unit for the full-color copy mode is set to be preferentially adjusted, the temperature of the fixing unit for monochrome copying is forcibly adjusted (S11). Then, after fixing is performed in the fixing unit for the black and white copy mode,
It is discharged to the discharge tray (S10).

With the above arrangement, when the sheet is detected to be thick paper, the temperature of the fixing unit for the full-color copy mode is preferentially adjusted regardless of the copy mode, and fixing is performed at this fixing unit. Be seen. That is, since the fixing portion for the full-color copy mode has a higher temperature than the fixing portion for the black-and-white copy mode, it is possible to give a sufficient amount of heat to melt and fix the toner image formed on the thick paper.

Therefore, it is possible to completely fix the toner image formed on the thick paper, and it is possible to obtain the required good copy image.

Further, when copying is executed in the composite copy mode, conventionally, for a black-and-white original, fixing is performed using the fixing unit for the black-and-white copy mode. However, in the fixing unit for the black and white copy mode, which has a low temperature, it is not possible to apply sufficient heat to completely melt the multi-layered toner image, and there is an unfixed toner image, and therefore it is good. I couldn't get a good copy image.

However, according to this embodiment, when the composite copy mode is set, the temperature of the fixing unit for the full-color copy mode is preferentially adjusted regardless of whether the original is black and white or color. At the same time, since fixing is performed using the fixing unit for the full-color copy mode, it is possible to give sufficient heat to melt even a toner image having a plurality of layers.

Therefore, it is possible to completely melt and securely fix the toner images of the plural layers formed on the paper,
A good copy image can be obtained.

[Embodiment 2] Another embodiment of the present invention will be described below with reference to FIGS. 2 and 5. For the sake of convenience of description, in this embodiment, an electrophotographic apparatus having the same structure as that of the electrophotographic apparatus of Embodiment 1 is used, and therefore, the description of members having the same numbers and copying operations will be omitted.

In the fixing unit 200 shown in FIG. 4, when fixing is performed by the upper fixing unit, the amount of oil applied to the surface of the upper heat roller 201 is adjusted by controlling the rotation of the eccentric cam 211. There is. For example, in the case of black-and-white copying on thick paper, the rotation of the eccentric cam 211 is controlled to be faster than that in the case of full-color copying so that the amount of oil application is smaller than that in the case of full-color copying. There is. That is, so that the oil application time (t ₁ ) for black-and-white copying on thick paper is shorter than the oil application time (t) for full-color copying, the oil application amount control unit (oil application) including S12 to S14 shown in FIG. It is controlled by a coating amount control means) 61.

Since the oil application time is determined based on the oil application time (t) when full color copying is performed, the oil application time (t ₁ ) when black and white copying is performed on thick paper is determined. , For example, t ₁ = 0, and if t ₁ is smaller than t, it is not particularly limited.

Here, the operation of executing black and white copy on thick paper will be described below with reference to FIGS.

First, after the monochrome copy selection key (not shown) is turned on, the copy start button (not shown) is turned on.
If N, as shown in FIG. 2, the paper 50 is conveyed from the paper feed tray 26 which is the manual paper feed unit, and if the paper 50 is detected as the thick paper 50b by the thick paper detection mechanism 300, the medium The heat roller 202 is the upper heat roller 201.
While moving to the side to form the press contact portion, the pressure contact portion is rotated, and the upper heat roller 201 is rotated in the counterclockwise direction, and accordingly, the upper heat roller 201 is rotated in the clockwise direction. Further, the oil application roller 208 is pressed against the upper heat roller 201, and the suction unit 1
00 is moved so as to be held in the upper position.

At this time, the heater lamp 204a of the upper heat roller is turned on so that the roller surface has a predetermined temperature, that is, 21
The temperature is raised to 0 ° C., and the medium heat roller 202 2
Of the two heater lamps 204b and 204c, only the heater lamp 204b is turned on to raise the temperature of the roller surface to a predetermined temperature, that is, 190 ° C.

The surface of the photoconductor 8 is charged by the charger 9.
Are uniformly charged, and the exposure optical system unit 4 scans the document on the document table 3. The reflected light from the document is guided to the exposure optical system section 4 without passing through the color separation filter and the slit, and is applied to the exposure point on the surface of the photoconductor 8 to form an electrostatic latent image on the photoconductor 8. Then, the electrostatic latent image is developed by the black developing tank 10,
The black toner image thus formed is transferred to the transfer belt 17 and then further transferred from the transfer belt 17 to a sheet.

The above-mentioned paper on which the toner image is transferred in this manner is conveyed by the suction unit 100 to the upper fixing portion formed at the pressure contact portion between the upper heat roller 201 and the middle heat roller 202. In the upper fixing unit, the toner images on the thick paper 50b are transferred to the upper and middle heat rollers 201.
Heated and melted by 202, and fixed on the thick paper 50b. At this time, the oil application amount control unit 61 (FIG. 5) controls the amount of oil supplied from the oil application roller 208 to the upper heat roller 201. That is, by increasing the rotation speed of the eccentric cam 211 to suppress the oil application time to t ₁ , an oil amount smaller than the oil application amount in the case of full color copying is supplied.

Next, the paper discharged from the fixing device 200 is discharged onto the paper discharge tray 31 by the paper discharge rollers 30.

The fixing control for the thick paper 50b will be described below with reference to FIG. Since S1 to S11 are the same as those in the above-described embodiment, the description thereof will be omitted. Further, FIG. 5 is provided with an oil application amount control unit 61 including S12 to S14 between S3 and S4 shown in the flowchart in FIG.

First, it is determined whether the oil application time is the oil application time (t) in the case of full-color copying or the oil application time (t ₁ ) in the case of black-and-white copying with thick paper (S12). If it is determined in S2 that the full color copy mode is being executed, oil is applied to the heat roller at the oil application time (t) in the case of full color copy (S13). If it is determined in S3 that the sheet is thick paper, oil is applied to the heat roller at the oil application time (t ₁ ) in the case of black and white copying with thick paper (S14). The oil application time at this time is t> t
_{Is 1} . That is, the oil application time (t ₁ ) for thick paper black and white copy is shorter than the oil application time (t) for full color copy, and the oil application amount for black and white copy at this time is the same as for full color copy. It is less than the amount of oil applied. When it is determined in S1 that the composite copy mode is being executed, oil is applied to the heat roller for the oil application time (t ₁ ) in the case of the full color copy described above.

Next, when the oil application is completed, S4,
It is fixed and discharged through S5 and S9 (S10). on the other hand,
If it is determined that the sheet is not thick paper in S3, S6, S
It is fixed and ejected through 7, S8 and S11 (S10).

By the way, normally, in the case of performing full-color copying, since toners of respective colors are laminated on the sheet, as shown in FIG. 4, oil is impregnated around the upper heat roller 201. An oil application roller 208 is provided, and oil is applied to the surface of the upper heat roller 201 to prevent color toner from adhering to the surface of the heat roller, that is, to prevent offset, thereby ensuring the peeling property of the color toner image, and also providing a full-color copy image. It is designed to give gloss to. On the other hand, when black-and-white copying is performed, the toner image formed is a single layer, and due to the characteristics of the black toner, the releasability between the sheet and the heat roller is good even if oil is not applied to the upper heat roller 201. Is.
Therefore, normally, when executing black and white copying, oil is not applied onto the heat roller.

However, as described above, even when black-and-white copying is performed using the thick paper 50b, the upper fixing unit, which is a fixing unit for full-color copying, is used as the fixing unit. Since the oil applied to the upper heat roller 201 is wasted,
Oil will remain on the top.

Further, the fixing device 200 shown in FIG. 4 is provided with the cleaning roller 206 for removing the toner and the like adhering to the surfaces of the heat rollers 201 to 203, but as described above, the thick paper 50b is used to make a black-and-white copy. When executed, the oil that has been wastefully applied to the upper heat roller 201 and must remain must be removed at all times, the deterioration of the cleaning roller 206 is promoted, and the upper heat roller 201 can be sufficiently cleaned. Can not
As a result, there is a problem that fixing failure occurs and a desired good copy image cannot be obtained.

Therefore, as described above, the oil application amount control unit 61 controls the oil application amount when performing black-and-white copying on thick paper to be smaller than the oil application amount when performing full-color copying. Is not applied unnecessarily, and the amount of oil remaining on the upper heat roller 201 is reduced, so that oil consumption can be reduced. Further, since the deterioration of the cleaning roller 206 that removes this oil can be suppressed, the surface of the upper heat roller 201 can be sufficiently cleaned, and the fixing failure in the fixing portion is reduced,
The required copy image can be obtained.

[0084]

As described above, the electrophotographic apparatus according to the present invention has the fixing section for the monochrome copy mode and the fixing section for the full color copy mode, and copies a plurality of originals on the same sheet. In an electrophotographic apparatus having setting means for setting the composite copy mode for, a thick paper detecting means for detecting that the sheet is thick paper is provided, and when the thick paper detecting means detects that the sheet is thick paper, When the composite copy mode is set before execution of copying, a fixing mechanism control unit is provided for adjusting the temperature of the fixing unit for the full-color copy mode and controlling the fixing mechanism so that the fixing unit performs fixing. It is a feature characterized by being.

Therefore, in the copying of a thick paper sheet which requires a heat quantity for melting the toner and the synthetic copy, the temperature of the fixing portion for the full color copy mode is adjusted, and the toner image is fixed by this fixing portion. There is an effect that defective fixing of the toner image on the sheet can be eliminated and a good copy image can be obtained.

As described above, the electrophotographic apparatus according to the second aspect is the same as the electrophotographic apparatus according to the first aspect, in which oil is applied to control the amount of oil applied to the fixing portion for the full-color copy mode. The configuration is characterized in that a quantity control means is provided.

Therefore, in addition to the effect of the first aspect, it is not necessary to waste the oil applied in the fixing portion and to remove the residual oil, so that the cleaning member such as the cleaning roller is inferior. Therefore, the fixing portion can be sufficiently cleaned, fixing defects in the fixing portion can be reduced, and a desired copy image can be obtained.

[Brief description of drawings]

FIG. 1 is a flowchart showing fixing control in an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an electrophotographic apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a cardboard detection mechanism provided in the electrophotographic apparatus of FIG.

FIG. 4 is a schematic configuration diagram of a fixing device provided in the electrophotographic apparatus of FIG.

FIG. 5 is a flowchart showing fixing control in another embodiment of the present invention.

[Explanation of symbols]

 51 fixing mechanism control unit (fixing mechanism control unit) 61 oil application amount control unit (oil application amount control unit) 300 thick paper detection mechanism (thick paper detection unit)

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hidetoshi Kaneko 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka

Claims (2)

[Claims] 1. An electrophotographic apparatus having a fixing unit for a black-and-white copy mode and a fixing unit for a full-color copy mode, and having setting means for setting a composite copy mode for copying a plurality of originals on the same sheet. The apparatus is provided with a thick paper detection means for detecting that the sheet is thick paper, and when the thick paper detection means detects that the sheet is thick paper and when the composite copy mode is set before execution of copying, An electrophotographic apparatus comprising a fixing mechanism control means for adjusting the temperature of the fixing unit for the full-color copy mode and controlling the fixing mechanism so that the fixing unit performs fixing. 2. The electrophotographic apparatus according to claim 1, further comprising oil application amount control means for controlling the amount of oil applied to the fixing portion for the full color copy mode.