JP2003248348A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus wherein the deterioration in image quality due to the melt-sticking of a toner image thermally fixed to an inserted sheet can be suppressed. <P>SOLUTION: When the sheet load in an ejection tray 293 is larger than a prescribed quantity (w) in the case of inserting the sheet to be inserted with a color image, the working speed of the image forming apparatus main body and the working speed of the insertion device are controlled to be stopped, then, such a failure is prevented that the sheet whose temperature becomes high due to the thermal fixation of the toner image is loaded on a bundle of sheets in the sheet loading part and the heat is supplied to the bundle of sheets, and also, the cooling efficiency by the heat radiation of the bundle of sheets loaded in the sheet loading part is enhanced. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer which forms an image on a sheet by heating and fixing a toner image.

[0002]

2. Description of the Related Art An image forming apparatus such as a copying machine or a printer which uses an electrophotographic system directly transfers a toner image from a photoconductor or an intermediate transfer belt to a sheet fed from a feeding section to a transfer section. Indirect transcription via The sheet with the unfixed toner image transferred is conveyed to the fixing device as it is,
Here, the unfixed toner image is heat-melted and fixed on the sheet.
When an image is formed on only one side of the sheet, the sheet on which the toner image is fixed on one side is discharged as it is or after being turned upside down. On the other hand, when images are formed on both sides of the sheet, the sheet on which the toner image is fixed on one side is reversed inside and conveyed in the apparatus,
After being conveyed again to the transfer portion, the toner image is transferred to the other surface, and the unfixed toner image is fixed by the fixing device, and then discharged as it is or with the front and back reversed, to the outside of the image forming apparatus.

A discharge tray or a sheet post-processing device is arranged outside the image forming apparatus, and various post-processing can be performed on the sheet by conveying the sheet to the sheet post-processing device. As such a sheet post-processing device, for example, a sheet storage / alignment device capable of storing 2000 sheets in one stack, an insert device, a folding device, a punching device, and the like are provided.

For example, in an apparatus in which an insert device is arranged on the upstream side of the sheet storage / alignment device in the sheet conveying direction, the sheet storage / alignment device moves from the image forming device.
An insert sheet used for identification or for a cover at the time of bookbinding can be inserted between a normal sheet bundle carried into the aligning device.

By using such a function, a sheet on which a color image is formed by a color copying machine (or printer) and a cover of a sheet bundle on which a monochrome image is formed by a monochrome copying machine (or printer) by an inserter Alternatively, it is also possible to insert into the slip sheet and perform bookbinding.

The image forming apparatus having such a function is
Generally, monochrome copiers (or printers) are more productive than color copiers (or printers),
In light printing work currently being done in the market (for example, printing work such as manuals and pamphlets), monochrome images occupy most pages, and the ratio of color images is usually small. , And monochrome copiers are in high demand because of their lower running costs than color copiers.

[0007]

However, by using the image forming apparatus having the sheet post-processing apparatus as described above, a sheet of a sheet bundle on which a monochrome image is formed or a sheet on which a color image is formed is inserted on a cover sheet. When inserted, the toner portion of the color image may adhere to the sheet on which the monochrome image is formed. Further, in a sheet in which a monochrome image is formed on both sides, the monochrome toner and the color toner fixed on each sheet may be fused with each other to deteriorate the image quality.

This is because when a sheet having a high temperature due to monochrome toner being fixed is stacked in a sheet storage portion in the sheet post-processing apparatus in an insufficiently cooled state,
By inserting the sheet on which the color image is formed into the cover or the interleaf sheet of the sheet bundle on which the monochrome image is formed, the melting point is caused by the heat of the sheet bundle on which the monochrome image is formed and the load of the stacked sheet bundle. This is due to the fact that the low color toner melts. This phenomenon is a major obstacle to improving the productivity of copying machines.

A color image is formed by transferring four color toners onto a sheet in an overlapping manner according to image information, and melting and mixing colors in a fixing unit. Color images use more toner than monochrome images. A material having a lower melting point than that of the monochrome toner is used as the color toner used when forming a color image. Therefore, the fixing temperature of the color toner is lower than that of the monochrome toner. In addition, there are a large number of sheets with monochrome toner fixed (for example, 1000 sheets or more).
When the sheets are stacked, the amount of heat applied to the sheet bundle by adding / stacking the sheet immediately after the monochrome toner is fixed to the sheet bundle may exceed the amount of heat radiated from the sheet bundle.

The reason why fusion occurs when a large number (here, 1000 or more) of sheets are stacked immediately after the monochrome toner is fixed will be described with reference to FIGS. 5 and 6.

5 and 6 are views for explaining the state of the sheets stacked on the discharge tray. The lowermost sheet and first sheet since from the lowest sheet slide into stacked in this order, then the n ₁ ~n ₃ th sheet sequentially onto each of these first sheet and n ₁ ~n ₃ sheet of sheet The relationship between the surface temperature and the elapsed time is shown.

First, the temperature of the sheet immediately after being discharged to the discharge tray (hereinafter referred to as the initial temperature) rises in the sheet conveying path as the number of stacked sheets increases.
It tends to rise as the number of sheets loaded increases.

The first sheet in FIG. 5 receives a small amount of heat from other stacked sheets, and also has a large amount of heat transferred by contact through the discharge tray and a large amount of heat radiated to the outside air. Therefore, the sheet temperature becomes lower over time.

However, as the number of sheets stacked increases,
The lower sheet (here, the n _1st sheet) is closer to the discharge tray, and the lower sheet cools faster, so the temperature behavior is similar to that of the 1st sheet. , The sheet located above this sheet (here, the n _2nd sheet) is less likely to drop the temperature of the sheet directly below, and is also stacked on the sheet bundle on the discharge tray due to the influence of the temperature rise in the sheet conveyance path. The initial temperature of the sheet to be discharged is also high, and the amount of heat supplied is larger than the amount of heat radiation because it is heated from the sheet directly below.

The seat located further above (here, n
_{For the third} sheet), the number of sheets up to the top sheet is small, so the amount of heat supplied from the upper sheet is small. Since the topmost sheet has a large contact area with the outside air, it is easy to radiate heat, and the temperature behavior is close to that of the first sheet.

In addition to the above, according to the experiments by the authors, even if the initial temperature of the stacked sheets is constant, fusion occurs depending on the position (the position of the sheet) in which the insert sheet is located. I found that I did or did not. It is considered that this is due to the influence of the weight of the stacked sheets, and the lower sheet receives the load of the upper sheet, so that the sheets are more easily fused.

Further, when an image is formed on both sides of the sheet, the initial temperature of the sheet becomes higher by passing through the fixing device twice than when an image is formed on only one side of the sheet.

Needless to say, fusing is less likely to occur when the amount of toner on the sheet is small and the temperature of the external environment is low. The amount of heat accumulated differs depending on the sheet type and sheet size, and the result is different. If the cpm is high, the heat supply amount increases, so that fusion is likely to occur.

For example, in our experiments,
It has been found that when a sheet on which a color image is formed is inserted between sheets of 300 to 1800 sheets on which a monochrome image is formed, fusion occurs.

Sheet size: A4 sheet type: 80 g sheet Total number of sheets loaded on the discharge tray: 2000 sheets Copier productivity (monochrome): 60 cpm when forming images on only one side (30 cpm when forming images on both sides ... 60 images / m ) Fixing temperature: 200 ° C. (magnetic one-component toner) Fixing temperature (color): 170 to 180 ° C. (non-magnetic two-component toner) Operating environment: 30 ° C. 85% Operating mode: Image formation on both sides of sheet Monochrome image: Toner consumption 50% or more original color image: Toner consumption 50% or more original As a measure against the above problems, a proposal to add a cooling fan near the discharge tray (Canon reference number 379913)
2) has been performed, but the cooling fan may disturb the consistency of the sheets on the discharge tray (there are various factors as described above. It is difficult to take this into consideration), and as the productivity increases, the cooling time decreases, making it difficult to take countermeasures using the cooling fan alone.

The present invention has been made in view of the above problems, and an object of the present invention is to realize an image forming apparatus capable of suppressing deterioration of image quality due to fusion of a toner image heat-fixed on an insert sheet. It is what

[0022]

In order to achieve the above object, in the present invention, an image forming means for forming an image accompanied by heat fixing of a toner image on a sheet, and an image is formed by this image forming means. A sheet stacking unit that stacks sheets, an insert unit that inserts an insert sheet between the stacked sheets, a color detection unit that detects an image color on the insert sheet, and a stacking amount of the sheets stacked in the sheet stacking unit. And the color detection unit detects that the image color of the insert sheet is color, and the sheet load amount detection unit detects that the sheet load amount is larger than a predetermined amount, the image And a control means for stopping and controlling the operating speed of the forming means and the insert means.

As described above, when the insert sheet having the color image is inserted and the sheet stacking amount in the sheet stacking unit is larger than the predetermined amount, the control means stops the operating speed of the image forming means and the insert means. By doing so, it is possible to prevent sheets that have become hot due to the heat fixing of the toner image from being stacked on the sheet bundle of the sheet stacking unit, and to prevent heat from being supplied to this sheet bundle, and thus to the sheet stacking unit. It is possible to improve the cooling efficiency of the stacked sheet bundle by radiating heat. That is, it is possible to prevent a portion of the sheet bundle that exceeds the melting point of the color toner used for the insert sheet from occurring.

Therefore, an insert sheet in which an image is generally formed with a color toner having a lower melting point than that of the monochrome toner is provided between the sheets in which the toner image with the monochrome toner, which has been a problem in the past, is heated and fixed and becomes high in temperature. It is possible to realize an image forming apparatus capable of suppressing deterioration of image quality due to fusion of a toner image heat-fixed on an insert sheet, which is likely to occur when inserting.

In addition to the above, when the above-mentioned control means detects that the image color of the insert sheet is color by the color detecting means and that the sheet stacking amount is larger than the predetermined amount by the sheet stacking amount detecting means. The operation speeds of the image forming means and the insert means may be controlled to be decelerated.

According to this, the sheet having a high temperature due to the heat fixing of the toner image is stacked on the sheet bundle of the sheet stacking unit and the amount of heat supplied to the sheet bundle per unit time is reduced. It is possible to improve the cooling efficiency by heat radiation of the sheet bundle stacked on the sheet stacking unit, and it is possible to prevent a portion exceeding the melting point of the color toner used for the insert sheet in the sheet bundle from occurring. Becomes

That is, an insert, which has been a problem in the prior art, is formed between sheets, in which a toner image of a monochrome toner is heated and fixed and is at a high temperature, with a color toner having a melting point generally lower than that of the monochrome toner. It is possible to realize the image forming apparatus capable of suppressing the deterioration of the image quality due to the fusion of the toner image heat-fixed on the insert sheet, which is likely to occur when the sheet is inserted.

Further, since the sheet bundle stacked on the sheet stacking portion can be cooled while operating the image forming means and the insert means, it is possible to suppress the deterioration of working efficiency as much as possible.

It is desirable that the above-mentioned control means controls the image forming means and the insert means to return to a normal operating speed when a predetermined time has elapsed from the start of the control.

In this way, the control means carries out the above-mentioned stop control or deceleration control until a predetermined time elapses, thereby cooling the sheet bundle stacked in the sheet stacking section to a desired temperature, and then normalizing again. By returning to the operating speed of 1), in addition to the effect of performing the above-mentioned stop control or deceleration control, it is possible to suppress the decrease in work efficiency as much as possible.

Further, the above-mentioned control means controls the image forming means and the insert means to return to the normal operation speed when the detection result of the sheet stacking amount detection means becomes a predetermined amount or less after the stop control. With such a configuration, the insert sheet in the sheet bundle is stacked by stacking more than a predetermined amount of sheets, which has been a problem in the past, due to the heat fixing of the toner image and having a high temperature. It is possible to prevent the generation of a portion exceeding the melting point of the color toner used in the above. It should be noted that when the detection result by the sheet stacking amount detection means here is less than or equal to a predetermined amount, for example, a part or all of the sheets in the sheet stack stacked on the sheet stacking unit by the user have been removed. For example, when the amount becomes less than a predetermined amount.

In addition to the above, an environment detecting means for detecting the use environment of the apparatus may be provided, and the control means may change the control conditions of the image forming means and the insert means according to the detection result of the environment detecting means. With such a configuration, it becomes possible to flexibly control the fusing conditions of the toner image heat-fixed on the insert sheet, which fluctuates according to the usage environment (temperature, humidity, etc.) of the apparatus. The deterioration of the image quality due to the fusing of the toner image heat-fixed on the insert sheet can be more reliably suppressed.

Further, an image forming means for forming an image on the sheet by heating and fixing the toner image, and a sheet stacking portion for stacking the sheet on which the image is formed by the image forming means,
Insert means for inserting an insert sheet between stacked sheets, input means for inputting the sheet information of the insert sheet inserted from the insert means by a user operation, and the stacking amount of the sheets stacked in the sheet stacking section And a control unit that controls the operation speed of the image forming unit and the insert unit based on the input sheet information and the detection result of the sheet load amount detection unit. It may be.

As described above, when the insert sheet is inserted, the operation speed of the image forming means and the insert means is controlled to be stopped or decelerated based on the input sheet information and the detection result of the sheet stacking amount detection means. The same effect as the stop control or the deceleration control described above can be obtained.

The sheet information here refers to various information such as the melting point of the toner and the material of the insert sheet. With such a structure,
For example, even when using various types of insert sheets that cannot be identified only by the image color on the insert sheet (for example, an insert sheet on which an image is formed with monochrome toner having a low melting point), image quality due to fusion of toner images It is possible to surely suppress the deterioration.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) First, a device configuration of an image forming apparatus G according to a first embodiment of the present invention will be described. FIG. 2 is a sectional view for explaining the image forming apparatus G.

In the figure, 200 is an image forming apparatus main body as an image forming means, and 280 is an automatic document feeder (ADF).
Is. Reference numeral 201 is a platen glass as a document placing table, and 202 is a document illumination lamp 203 and a scanning mirror 204.
˜206 and the like. The scanner 202 is reciprocally scanned in a predetermined direction by a motor (not shown), the reflected light from the original is transmitted through the lens 207 through the respective scanning mirrors 204 to 206, and the image sensor unit 20.
An image is formed on the CCD sensor in 8.

Reference numeral 209 denotes an exposure control section composed of a laser, a polygon scanner, etc., and an image sensor section 208.
Laser light 219 that has been modulated based on an image signal that has been converted into an electric signal and subjected to predetermined image processing described later.
Is irradiated onto the photosensitive drum 211.

Around the photosensitive drum 211, a primary charging device 212, a developing device 213, a transfer charging device 216, a separation charging device 217, a pre-exposure lamp 214, and a cleaning device 215 are installed.

In the image forming unit 210, the photosensitive drum 211 is rotated in the direction of the arrow in the figure by a motor (not shown), is charged to a desired potential by the primary charger 212, and then is exposed from the exposure controller 209. Laser light 2
An electrostatic latent image is formed by 19. The electrostatic latent image formed on the photosensitive drum 211 in this way is transferred to the developing device 21.
3 is developed and visualized as a toner image.

The right cassette 221 and the left cassette 2
22, upper cassette 223 or lower cassette 224
The sheets picked up by the pickup rollers 225 to 228 arranged in the respective cassettes are fed to the image forming apparatus main body 200 by the feeding rollers 229 to 232 which feed the sheets from the respective cassettes. The sheet thus fed is fed to the transfer belt 234 by the registration roller 233, and the visualized toner image is transferred to the sheet by the transfer charger 216.

After the toner image is transferred onto the sheet, the cleaning device 215 cleans the residual toner on the photosensitive drum 211, and the pre-exposure lamp 214 erases the residual charge. On the other hand, the sheet after the toner image is transferred is
It is separated from the photoconductor drum 211 by the separation charging device 217 and sent to the fixing device 235 by the transfer belt 234.

Then, the sheet sent to the fixing device is subjected to pressure and heat treatment, and the sheet on which the toner image has been fixed is discharged by the discharge roller 236 to the outside of the apparatus. The image forming apparatus main body 200 is equipped with a deck 250 that can store, for example, 4,000 sheets. The lifter 251 of the deck 250 rises according to the amount of sheets so that the uppermost sheet always contacts the pickup roller 252,
The sheet is sent to the image forming apparatus main body 200 by the feeding roller 253. In addition, a multi-manual feed tray 254 on which 100 sheets can be stacked is arranged on the side surface of the image forming apparatus main body 200.

Further, in FIG. 2, reference numeral 237 denotes an ejection flapper, which switches the sheet conveyance path to either the conveyance path 238 side or the discharge path 243 side. A lower conveyance path 240 reverses the sheet sent out from the discharge roller 236 through the reversing path 239, and then guides the sheet to the re-feeding path 241.

The sheet fed by the feeding roller 230 from the left cassette 222 is also guided to the refeeding path 241. A re-feeding roller 242 feeds the sheet to the image forming unit 210. A discharge roller 244 is disposed near the discharge flapper 237 and discharges the sheet guided to the discharge path 243 side by the discharge flapper 237 to the outside of the apparatus.

When images are to be formed on both sides of a sheet (duplex copying), the discharge flapper 237 is raised and the sheet having the image formed on one side is conveyed through the conveying path 238, the reversing path 239 and the lower conveying path 240. Refeeding path 241
Lead to. At this time, the trailing edge of the sheet comes out of the transport path 238 by the reversing roller 245, and
The sheet 45 is carried into the reversing path 239 to a position where the trailing edge of the sheet 45 is still nipped, and then the reversing roller 245 is reversed to feed the sheet to the lower conveying path 240, and the sheet is fed to the other surface of the sheet. An image is formed on both sides of the sheet by forming an image with the sheet.

When the sheet is discharged from the image forming apparatus main body 200 while being turned upside down, the discharge flapper 237 is raised upward to guide the sheet to the conveying path 238, and the rear end of the sheet is conveyed inside the conveying path 238 by the reversing roller 245. The sheet is carried into the reversing path 239 to the position where it remains, and then the reversing roller 245 is reversed, so that the sheet is reversed upside down and conveyed to the discharge roller 244.

Reference numeral 290 denotes a post-processing device that aligns and binds the sheets discharged from the image forming apparatus main body 200, and stacks and aligns the sheets discharged one by one on the processing tray 294.

When the discharge and stacking of a predetermined amount of sheets on which images have been formed on the processing tray 294 are completed, the sheet bundle is stapled and discharged as a bundle to the discharge tray 292 or 293 as a sheet stacking unit. The discharge tray 293 is arranged to be movable up and down by a motor (not shown),
Before the image forming operation is started, the movement of the processing tray 294 is controlled so as to be the position of the processing tray 294.

The discharge tray 293 is adapted to move downward in accordance with the number of stacked sheets, and its movement control is performed by the discharge tray position detecting sensor 302 and the uppermost sheet height detecting sensor which constitute the sheet stacking amount detecting means. 301 of 2
It is performed based on the detection data from one sensor.

Reference numeral 291 is a sheet tray for stacking insert sheets to be inserted between the discharged sheets, 300 is an insert sheet detection sensor as color detection means, and 298.
Is an insert device as an insert means for inserting an insert sheet between the sheets stacked on the discharge tray 293, and has a sheet tray 291 and an insert sheet detection sensor 300. A Z-folding machine 295 Z-folds the discharged sheet. Also, 2
Reference numeral 96 denotes a bookbinding machine that binds a part of ejected sheets together by center folding and stapling, and the bound sheet bundle is ejected to an ejection tray 297.

Next, the circuit configuration of the control circuit as the control means in the image forming apparatus G will be described.

FIG. 3 is a block diagram for explaining the circuit configuration of the control circuit in the image forming apparatus G. In FIG. 3, reference numeral 100 denotes a document reading unit 118 and an image forming unit 1.
This is a main body control unit including drive control means such as 05. The main body control unit 100 converts the image data read by the CCD 101 into desired image data in the image processing unit 102, and in the image data selector 103,
It controls which of the laser unit 104, the image data compression / expansion unit 107, the image memory 108, and the function control unit 109 to send the read image data to the document feeding device control unit 116. Sending commands, post-processing device (finisher) control unit 11
This is for performing device control of the image forming apparatus and image data control for instructing which mode is to be set for 7.

Reference numeral 101 denotes a CCD, which is a document reading section 118 including a document table, a document irradiation section, and an optical system.
Then, the original image that captures the reflected light of the original image obtained by illuminating the original is photoelectrically converted, and the image data is output. 1
In the image processing unit 02, the image data output from the CCD 101 is processed corresponding to the image processing function set by the operation unit 119.

Reference numeral 103 denotes a laser unit 10 described later.
4, image data compression / decompression unit 107, image memory 10
8 and the function control unit 109 are connected so as to be able to communicate with each other via an image data bus, and the direction in which the image data flows is selected according to control information from the main body control unit 100 that determines the flow of the image data. It is an image data selector.

Reference numeral 104 is a laser unit for performing laser exposure on the image forming section 105 for developing image data on a sheet. Reference numeral 105 denotes an image forming unit for actually developing the laser-exposed image data on a sheet as described above.

Reference numeral 106 denotes an inter-CPU communication I / F for communicating control information between the main body control unit 100 and a function control unit 109 described later. A hard disk (HD) 112, which is a large-capacity nonvolatile memory, stores the image data output from the image data selector 103.
In order to save the occupancy rate of the image data on the HD 112 when it is stored in the
Image data selector 10
3 is an image data compression / decompression unit that decompresses the original image data when transferring the data.

An image memory 108 is a volatile memory for temporarily storing the image data sent from the image data selector 103 and transferring the temporarily stored image data to the image data selector. Is.

Reference numeral 109 communicates with the main body control unit 100, and sends the image data sent from the image data selector 103 to a scan image conversion unit 113 described later, or sent from a network communication I / F 115 described later. The image data control information for flowing the image data sent from the print image conversion unit 114 for converting the incoming print image data to the image data selector 103 and the image forming apparatus control information from the operation unit 119 of the main body are stored in the CPU. It is a function control unit that communicates control information with the main body control unit 100 via an inter-CPU communication I / F 106 that performs communication between the CPUs.

Reference numeral 110 denotes an inter-CPU communication I / F for communicating control information of image data stored in the HD 112 between an HD control unit 111 and a main body control unit 100 which will be described later.

Reference numeral 111 denotes an image data compression / decompression unit 107.
The control for writing the image data streamed from the HD 112 to the HD 112, reading the image data stored in the HD 112, and streaming the image data to the image data compression / decompression unit 107 is sent through the inter-CPU communication I / F 110. H based on the control information from the main body control unit 100
An HD controller that controls D112.

Reference numeral 112 denotes an HD which is a non-volatile memory in which the image data sent from or sent by the image data compression / expansion unit 107 is written and read under the control of the HD control unit 111.

Reference numeral 113 allows the image data sent from the image data selector 103 under the control of the main body control unit 100 to be read by application software operating on a host computer network-connected in a network communication I / F 115 described later. It is a scan image conversion unit that performs conversion so that

As described above, the image data 114 is the image data described in the page description language (PDL) transferred from the application software operating on the host computer network-connected in the network communication I / F 115 described later. A print image conversion unit that converts image data that can be printed out by the image forming unit 105 of the forming apparatus.

Reference numeral 115 denotes a network communication I / F for connecting to the image forming apparatus via a network, which communicates image data and control information with a device (computer etc.) on the network based on a specific communication protocol (protocol). I do.

Reference numeral 116 is an automatic document feeder 2 for feeding a plurality of documents, which will be described in detail later with reference to FIG.
A document feeding device control unit that controls 80, and feeds a document based on control information from the main body control unit 100.

Reference numeral 117 denotes a post-processing apparatus control unit for performing post-processing of the sheet after image formation, which will be described later in detail with reference to FIG. I do.

Reference numeral 118 denotes a document reading section including an optical unit driving device for driving an optical unit including a document irradiating unit, an optical unit, and the like. The document reading unit 118 optically irradiates a document based on control information from the main body control unit 100. By driving the unit, reflected light of the original image is given to the CCD 101.

Reference numeral 119 denotes an image forming apparatus main body 200 (see FIG.
(See) the operation unit. The key information input from the operation unit 119 is notified to the function control unit 109, the function control unit 109 analyzes the command of the key, and the operation control information of the device is transmitted to the main body control unit 100 between the CPU I / O units. It is notified via F106.

FIG. 1 shows an operation sequence flowchart of the image forming apparatus according to this embodiment. In step S300, after the main body control unit 100 issues an instruction to start a printing operation (insert print in the drawing) accompanied by an insert sheet insertion operation by the insert device 298, the insert sheet detection sensor 300 in the insert device 298 of the insert device 298 is instructed in step S301. The data is checked, and in the case of color, the process proceeds to step S302, and in the case of monochrome, the series of control is omitted and the process proceeds to step S308. In step S302, it is determined whether or not the instructed job performs a monochrome image forming operation for more than 1000 sheets. If it exceeds, step S303, and if not, step S3.
Go to 08.

In step S303, the printing operation proceeds, the insert sheet is inserted on the discharge tray 293 as a cover or slip sheet, and the aligned sheet bundle is stacked. The total number of stacked sheets is 1000. Judge whether the number of sheets has been exceeded. Specifically, this is the stacking height of sheets on the discharge tray (the size in FIG. 2) as the sheet stacking amount which is found from the two detection data of the discharge tray position detection sensor 302 and the uppermost sheet height detection sensor 301 in FIG. It is determined whether or not x) exceeds a predetermined dimension w as a predetermined amount. Therefore, even if it is not exactly 1000,
The height may be equivalent to 1000 sheets.

Step S303 is repeated until the height equivalent to 1000 sheets is exceeded, and if exceeded, step S304.
Go to.

In step S304, the result of the detection data analysis is transmitted from the post-processing apparatus controller 117 to the image forming apparatus main body controller 100, the insert sheet inserting operation and the image forming operation are stopped, and the process proceeds to step S305. In the section 119, "Please remove the sheet on the discharge tray" is displayed.

Thereafter, the process proceeds to step S306, and the output value of the uppermost sheet height detecting sensor 301 is constantly observed.
When the device operator removes the sheets by looking at the display of the operation unit 119 (not necessarily the total number of sheets), the uppermost sheet height detection sensor 301 is turned off and the discharge tray is raised until it is turned on. If the dimension x in the figure becomes smaller than the predetermined dimension w, the process proceeds to step S307. If it does not become smaller, the printing operation in step S304 (that is, the insert sheet inserting operation and the image forming operation) is stopped until it becomes smaller, and the display in step S305 is continued. Step S307
Then, the display in step S305 of the operation unit 119 is displayed as OF.
Set to F and restart the printing operation. Then step S3
08, if the job is completed, step S3
09, and if not completed, step S30
Return to step 3 to continue the job.

In this way, 10 sheets are put on the discharge tray.
When the equivalent of 00 sheets has been stacked, a display is displayed to alert the operator to stop control, and after this stop control, the detection result of the sheet stacking amount detection means indicates the sheet bundle stacked on the sheet stacking unit by the operator. When some or all of the sheets are removed and the number of sheets becomes 1,000 or less, the image forming apparatus main body and the insert apparatus are controlled to return to the normal operation speed so that they are used as insert sheets in the sheet bundle. It is possible to prevent the generation of a portion exceeding the melting point of the color toner. In this way
Since the sheet is cooled by radiating heat only by removing a part of the sheet bundle by the operator and replacing it with another place, it is possible to suppress the above-described problem of toner fusion.

As described above, even when a color output sheet is used as the insert sheet and the sheet is inserted as a cover sheet or interleaf sheet between the monochrome output sheets, it is possible to add software without adding special parts such as a cooling fan. With only the above modification, it is possible to realize an image forming apparatus capable of preventing deterioration of image quality due to fusion of a toner image heat-fixed on an insert sheet.

In the present embodiment, the above-mentioned predetermined dimension w has been described as a fixed value that is determined in advance, but it may be a variable value that can be changed / set by the operator or service person as needed. (Second Embodiment) FIG.
FIG. 8 shows an operation sequence flowchart of the image forming apparatus according to the second embodiment of the present invention. The present embodiment is an application of the above-described first embodiment, and is a form in which steps S310 to S312 are added to the first embodiment.

According to the operation sequence flowchart in this embodiment, even if the operator does not remove the sheet even though the print operation is stopped in step S304 and the display in step S305 is displayed, the operation sequence is as in step S310. If the operation is stopped for a predetermined time t, and the operation is restarted after the sheet is cooled, the problem of toner fusion does not occur.

Further, as steps S311 and S312, a step of confirming whether or not the image is formed on both sides of the sheet and confirming the condition of the use environment by the environment detecting means described later is added to the operation stop condition. That is, an environment detection unit that detects the environment in which the device is used (temperature, humidity, etc.) is provided, and based on the detection result by this environment detection unit and information indicating whether the image forming operation is for both sides of the sheet,
The configuration is such that the control conditions of the image forming apparatus main body and the insert device are changed.

With such a structure, it becomes possible to flexibly control the fusing conditions of the toner image heat-fixed on the insert sheet, which fluctuates according to the environment in which the apparatus is used. It is possible to more reliably suppress the deterioration of the image quality due to the fusing of the toner image heat-fixed on. Further, since it is possible to more accurately control the operation corresponding to the toner image fusion condition, it is possible to perform the stop control of the image forming apparatus main body and the insert device only when it is necessary to avoid the fusion of the toner image. Therefore, it is possible to suppress the deterioration of the work efficiency of the device as much as possible.

Further, as described above, when a predetermined time has elapsed from the start of the stop control, the image forming apparatus main body and the insert device are controlled so as to be returned to the normal operation speed, so that the sheet bundle is cooled to a desired temperature. Then, by returning to the normal operation speed again, in addition to the effect of performing the above-described stop control, it is possible to suppress the decrease in work efficiency as much as possible.

In each of the above embodiments, step S3
In 04, by controlling the operation speed of the image forming apparatus main body and the insert apparatus to stop, the printing operation is stopped and the time for cooling the stacked sheet bundle is secured. However, the present invention is not limited to this. Instead, for example, the operating speeds of the image forming apparatus main body and the insert device are controlled to be decelerated (that is, down sequence) (the cpm is lowered), so that the sheets having a high temperature due to the heat fixing of the toner image are stacked on the sheet bundle. By reducing the amount of heat supplied to the sheet bundle per unit time, it is possible to improve the cooling efficiency by radiating heat of the sheet bundle, and to improve the melting point of the color toner used for the insert sheet in the sheet bundle. It is possible to prevent the crossing portion from occurring.

Further, since the sheet bundle stacked on the sheet stacking unit can be cooled while operating the image forming apparatus main body and the insert apparatus, downtime of the apparatus can be reduced and production efficiency can be improved. be able to.

In each of the above embodiments, one job 10
Although the fixed conditions are 00 sheets, a predetermined size w, a predetermined time t, etc., these values are set according to the operation mode, environment, etc.
It is possible to cope with various usage environments by automatically changing the value, or manually changing the value by a service person (or an operator) using the input means.

In each of the above-described embodiments, the case where the insert sheet is a normal color output sheet is shown. For example, a model using a toner having a low melting point even if the insert sheet is a monochrome output sheet. Similar problems are expected with the output sheet of. The same problem may occur when inserting a special sheet such as an OHP sheet, a second original drawing, a postcard, or the like.

Therefore, in order to apply the operation stop condition even when the insert sheet is a sheet other than the normal color output sheet, various information such as information regarding the melting point of the toner, the material of the insert sheet, and the like are input from the operation unit. The information may be manually input as sheet information, and in this case, deterioration of image quality due to fusion of toner images can be suppressed even when various types of insert sheets are used.

As described above, when the insert sheet is inserted, stop control or deceleration control of the operating speed of the image forming apparatus main body and the insert apparatus is performed based on the input sheet information and the detection result of the sheet stacking amount detection means. Thus, in addition to the effect of performing the stop control or the deceleration control described above, various types of insert sheets that cannot be identified only by the image color on the insert sheet (for example, an image is formed with monochrome toner having a low melting point). Even when an insert sheet or the like) is used, deterioration of image quality due to fusion of toner images can be surely suppressed.

[0088]

As described above, according to each invention of the present application, it is possible to realize the image forming apparatus capable of suppressing the deterioration of the image quality due to the fusion of the toner image heat-fixed on the insert sheet. .

[Brief description of drawings]

FIG. 1 is an operation sequence flowchart of the image forming apparatus according to the first embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining the configuration of the image forming apparatus.

FIG. 3 is a block diagram for explaining a circuit configuration of a control circuit in the image forming apparatus.

FIG. 4 is an operation sequence flowchart of the image forming apparatus according to the second embodiment of the present invention.

FIG. 5 is a diagram illustrating a state of sheets stacked on a discharge tray in a conventional image forming apparatus.

FIG. 6 is a diagram illustrating a state of sheets stacked on a discharge tray in a conventional image forming apparatus.

[Explanation of symbols]

200 Image forming apparatus main body 210 Image forming unit 250 decks 280 Automatic Document Feeder (ADF) 290 Aftertreatment device 292 Output tray 293 Ejection tray 301 Uppermost sheet height detection sensor 302 Ejection tray position detection sensor G image forming apparatus

Continued front page    F term (reference) 2H027 DC01 DC02 DC09 DD05 DE02                       DE03 DE07 ED16 EE03 EE05                       EE07 EF09 FA27 FB06                 2H072 AA01 AA12 AA17 AA25 AA26                       AA30 AA36 AB09 FB01 FB06                 3F107 AA01 AB01 AC02 AC04 BA02                       CA04

Claims (6)

[Claims] 1. An image forming unit for forming an image on a sheet by heating and fixing a toner image, a sheet stacking unit for stacking a sheet on which an image is formed by the image forming unit, and an insert between the stacked sheets. Insert means for inserting a sheet, color detection means for detecting the image color on the insert sheet, sheet load amount detection means for detecting the load amount of the sheets stacked on the sheet stacking portion, and the color detection means Detects that the image color of the insert sheet is color, and the sheet stacking amount detection means detects that the sheet stacking amount is larger than a predetermined amount, the operation speed of the image forming means and the insert means is stopped and controlled. An image forming apparatus comprising: a control unit. 2. An image forming unit for forming an image on a sheet by heating and fixing a toner image, a sheet stacking unit for stacking sheets on which an image is formed by the image forming unit, and an insert between the stacked sheets. Insert means for inserting a sheet, color detection means for detecting the image color on the insert sheet, sheet load amount detection means for detecting the load amount of the sheets stacked on the sheet stacking portion, and the color detection means When it is detected that the image color of the insert sheet is color, and when the sheet stacking amount detecting means detects that the sheet stacking amount is larger than a predetermined amount, the operation speed of the image forming means and the insert means is controlled to be decelerated. An image forming apparatus comprising: a control unit. 3. The control unit controls the image forming unit and the insert unit to return to a normal operating speed when a predetermined time has elapsed from the start of the control. The image forming apparatus according to item 1. 4. The control unit controls the image forming unit and the insert unit to return to a normal operating speed when the detection result of the sheet stacking amount detection unit becomes equal to or less than the predetermined amount after the stop control. The image forming apparatus according to claim 1, wherein: 5. An environment detecting unit for detecting an environment in which the apparatus is used, wherein the control unit changes control conditions of the image forming unit and the insert unit according to a detection result of the environment detecting unit. The image forming apparatus according to any one of claims 1 to 4. 6. An image forming unit for forming an image on a sheet by heating and fixing a toner image, a sheet stacking unit for stacking the sheet on which the image is formed by the image forming unit, and an insert between the stacked sheets. Insert means for inserting a sheet, input means for inputting sheet information of an insert sheet inserted from the insert means by a user operation, and sheet stacking for detecting a stacking amount of the sheets stacked in the sheet stacking section It is characterized by having an amount detection means and a control means for performing stop or deceleration control of operating speeds of the image forming means and the insert means based on the input sheet information and a detection result by the sheet stacking amount detection means. Image forming apparatus.