JP7441406B2 - Ejection device and image forming device - Google Patents

Description

The present invention relates to a discharging device for discharging sheets such as paper, and an image forming device including a copying machine, a printer, a facsimile machine, or a multifunction device or printing machine thereof.

Conventionally, image forming apparatuses such as copying machines, printers, and printing machines have been known to place sheets such as paper ejected from the apparatus on a placing section (sheet ejection tray) (for example, Patent Document (See 1).
Specifically, the placing section is formed to extend from the upstream side in the sheet discharging direction to the downstream side in the sheet discharging direction. Then, the printed sheets are stacked on the receiver, and the user takes out the sheets stacked on the receiver.

On the other hand, Patent Document 1 discloses that, in addition to a shift tray that moves up and down depending on the number of sheets loaded, a pair of paper ejection rollers and a shift tray are used for the purpose of improving the consistency of sheets regardless of the type of sheets or the presence or absence of curls. A technique is disclosed in which a movable auxiliary tray is provided between the two.

In the conventional technology, when the sheets discharged from the discharge section are curled downward, a stacking failure occurs in which the sheets are not placed neatly on the loading section.
On the other hand, it is possible to apply the technology disclosed in Patent Document 1 to place the sheet in the downwardly curled state on an auxiliary tray instead of placing it on the shift tray. However, in that case, uncurled sheets are also placed on the auxiliary tray, which reduces the number of sheets that can be stacked on the tray.

This invention was made in order to solve the above-mentioned problems, and it is possible to efficiently solve the problem of stacking defects in sheets placed on the stacking section without reducing the number of sheets that can be stacked unnecessarily. An object of the present invention is to provide a discharge device and an image forming device that can reduce the cost.

The discharging device according to the present invention includes a stacking section disposed below the discharging section and capable of placing a sheet discharged from the discharging section, and a stacking section disposed below the discharging section and above the loading section. A movable loading position that is movable between an auxiliary loading position where a sheet discharged from the discharge section can be placed and a retreat position that does not prevent sheets discharged from the discharge section from being placed on the loading section. and a curl detection means for detecting a downward curl state in which a sheet discharged from the discharge section is curled in a concave shape in a direction opposite to the discharge direction, and the movable loading section is configured to When the downward curl state is not detected, the curl detecting means is located at the retracted position, and when the downward curl state is detected by the curl detecting means, the movement is controlled to be located at the auxiliary placement position , and the curl detecting means is A plurality of distance measuring sensors are arranged in parallel at intervals in the height direction between the discharge section and the placement section .

Advantageous Effects of Invention According to the present invention, there is provided a discharging device, an image discharging device, and an image discharging device that can efficiently reduce the problem of stacking defects in sheets placed on a loading section without unnecessarily reducing the number of sheets that can be stacked. A forming device can be provided.

1 is an overall configuration diagram showing an image forming apparatus in an embodiment of the present invention. FIG. 2 is a configuration diagram showing the main parts of the ejection device. It is a figure which shows the operation|movement of an ejection device when a downward curl state is detected by the distance measurement sensor. FIG. 6 is a diagram showing the operation of the discharge device when a high temperature and high humidity state is detected by a temperature and humidity sensor. It is a figure which shows the operation|movement of an ejection device when the state where the loading height exceeds the predetermined value is detected by the distance measurement sensor. It is a flowchart which shows movement control of a movable mounting part.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and repeated explanations thereof will be simplified or omitted as appropriate.

First, referring to FIG. 1, the overall configuration and operation of image forming apparatus 100 will be described.
In FIG. 1, 100 is a copying machine as an image forming device, 6 is a process cartridge (image forming section) that forms a toner image (image) on the photosensitive drum 1, and 7 is image information transmitted from the original reading section 10. An exposure section (writing section) that irradiates the photoreceptor drum 1 with exposure light L based on the above is shown.
Further, 9 is a transfer roller that transfers the toner image carried on the photoreceptor drum 1 onto a sheet P that is conveyed to a transfer position, 10 is a document reading unit that optically reads image information of a document, and 12 is a transfer roller that transfers a toner image carried on the photoreceptor drum 1 to a sheet P that is conveyed to a transfer position; A feeding device (paper feeding cassette) in which sheets P are stored is shown.
Further, 20 is a fixing device that fixes the unfixed image carried on the sheet P, 21 is a fixing roller installed in the fixing device 20, 22 is a pressure roller installed in the fixing device 20, and 25 is a fixing roller. An infrared heater for heating, 30 a discharge device for discharging the printed sheet P to a discharge tray 33, and 45 a discharge device for discharging the sheet P after printing to a transfer position (transfer nip) where the photosensitive drum 1 and the transfer roller 9 come into contact. The registration roller (timing roller) being conveyed is shown.

Here, referring to FIG. 1, the process cartridge 6 includes a photosensitive drum 1 as an image carrier, a charging section 4, a developing section 5, and a cleaning section 2, which are integrally constituted as a unit. The process cartridge 6 is removably (replaceably) installed in the image forming apparatus main body 100.
The photoreceptor drum 1 is a negatively chargeable organic photoreceptor, and has a photosensitive layer and the like provided on a drum-shaped conductive support. Further, the photosensitive drum 1 is rotated counterclockwise in FIG. 1 by being rotationally driven by a drive motor (not shown).
The charging unit 4 is a charging roller formed by covering the outer periphery of a conductive metal core with an elastic layer of medium resistance, and is in contact with the photoreceptor drum 1 . A predetermined voltage (charging bias) is applied to the charging unit 4 from a power supply unit (not shown), thereby uniformly charging the surface of the opposing photoreceptor drum 1.

The developing section 5 (developing device) mainly includes a developing roller 51 facing the photoreceptor drum 1, two developing conveyance screws 53 arranged in parallel with each other via a partition member, and a doctor blade 52 facing the developing roller 51. Consists of. A two-component developer consisting of carrier and toner is housed within the developing section 5 . Then, the developing section 5 attracts toner to the latent image formed on the photoreceptor drum 1 to form a desired toner image.
The cleaning section 2 includes a cleaning blade 2a that comes into contact with the photoreceptor drum 1 to remove untransferred toner adhering to the surface of the photoreceptor drum 1, and a cleaning blade 2a (not shown) that removes untransferred toner removed and collected by the cleaning section 2. A conveyance screw 2b for conveying the waste toner toward the waste toner collection container is installed.

Referring to FIG. 1, operations during normal image formation in image forming apparatus 100 will be described.
First, when a document is set on the document table and a print button is pressed, the image information of the document is read by the document reading section 10 and the image information is transmitted to the exposure section 7 . Then, exposure light L (laser light) based on the image information is emitted from the exposure section 7 toward the surface of the photoreceptor drum 1.
On the other hand, the photosensitive drum 1 is rotating in the direction of the arrow (counterclockwise). First, the surface of the photoreceptor drum 1 is uniformly charged at the portion facing the charging section 4 (this is a charging step). In this way, a charged potential (approximately -900V) is formed on the photoreceptor drum 1. Thereafter, the charged surface of the photosensitive drum 1 reaches the irradiation position of each exposure light L. Then, the potential of the portion irradiated with the exposure light L becomes a latent image potential (approximately 0 to -100V), and an electrostatic latent image is formed on the surface of the photoreceptor drum 1 (in the exposure process). ).

Thereafter, the surface of the photosensitive drum 1 on which the electrostatic latent image is formed reaches a position facing the developing section 5 (developing roller 51). Then, toner is supplied onto the photoreceptor drum 1 from the developing section 5, and the latent image on the photoreceptor drum 1 is developed to form a toner image (this is a developing step).
Thereafter, the surface of the photosensitive drum 1 after the development process reaches a transfer nip (transfer position) with the transfer roller 9. At the transfer nip between the transfer roller 9 and the transfer roller 9, a transfer bias (a bias with a polarity different from that of the toner) is applied to the photoreceptor onto the sheet P conveyed by the registration roller 45. The toner image formed on the drum 1 is transferred (this is a transfer process).

Thereafter, the surface of the photosensitive drum 1 after the transfer process reaches a position facing the cleaning section 2. At this position, the cleaning blade 2a mechanically removes the untransferred toner (including other deposits such as paper dust and agglomerated toner) remaining on the photoreceptor drum 1, and the cleaning section 2a (This is a cleaning process.)
After the cleaning process, the surface potential of the surface of the photosensitive drum 1 is reset to approximately 0V by neutralization by a static eliminating device (not shown). Then, a series of image forming processes on the photosensitive drum 1 are completed.

On the other hand, the sheet P conveyed to the transfer nip (transfer position) between the photosensitive drum 1 and the transfer roller 9 operates as follows.
First, the uppermost sheet P stored in the feeding device 12 is fed by the paper feeding roller 41 toward the conveyance path.
Thereafter, the sheet P reaches the position of the registration rollers 45. Then, the sheet P that has reached the position of the registration roller 45 is conveyed toward the transfer nip (transfer roller 9) at the same timing to align with the image formed on the photoreceptor drum 1.

The sheet P after the transfer process passes through the transfer nip (transfer roller 9) and then reaches the fixing device 20 via the conveyance path. The sheet P that has reached the fixing device 20 is fed between the fixing roller 21 and the pressure roller 22, and is heated by the fixing roller 21 (which is heated by an infrared heater 25 installed inside). The image is fixed by the pressure received from both members 21 and 22. The sheet P on which the image has been fixed is sent out from between the fixing roller 21 and the pressure roller 22 (which is a fixing nip portion), and then is ejected from the image forming apparatus main body 100 by the ejecting device 30 . Specifically, the printed sheet P is discharged from the apparatus from the discharge port A (discharge section) by the discharge roller pair 31, and is placed on the discharge tray 33 as a loading section.
In this way, a series of image forming processes is completed.

Next, the discharge device 30, which is characteristic of the image forming apparatus 1 according to the present embodiment, will be described in detail.
As previously explained using FIG. 1, the discharge device 30 is a device on which the sheet P conveyed and discharged by the pair of discharge rollers 31 is placed.
As shown in FIGS. 1 and 2, the ejection device 30 in this embodiment includes a ejection roller pair 31, an ejection tray 33 (placement section), a movable ejection tray 35 (movable placement section), and a curl detection means. It is composed of a plurality of distance measuring sensors 71, 72, etc.

The ejection tray 33 as a loading section is disposed below the ejection port A (an opening in which the ejection roller pair 31 is installed in the image forming apparatus main body 1) as an ejection section. It is configured such that the sheet P discharged from the section) can be placed thereon. In order to increase the number of stacked sheets (loading height) of the sheets P (to enable a large amount of stacking), the distance in the height direction of the discharge tray 33 from the discharge port A is set to be relatively large. Note that the discharge tray 33 in this embodiment also functions as a part of the exterior of the image forming apparatus main body 100.
The ejection roller pair 31 has a plurality of roller parts installed at intervals on the shaft part, and two rollers contact each other to form a nip. ). The discharge roller pair 31 is rotated in the direction of the arrow in FIG. 2 by being driven by a drive mechanism.

The movable discharge tray 35 as a movable loading section is configured to be movable between a retracted position shown by a solid line in FIG. 2 and an auxiliary loading position shown by a broken line in FIG.
The "retreat position" of the movable discharge tray 35 is a position that does not prevent the sheet P discharged from the discharge port A (discharge section) from being placed on the discharge tray 33 (placing section). That is, when the movable ejection tray 35 is located at the retracted position (the position shown in FIGS. 1, 5, etc.), the sheet P ejected from the ejection port A can be moved without interfering with the movable ejection tray 35. , and will be placed on the discharge tray 33 as is. In this embodiment, when the movable ejection tray 35 is located at the “retracted position”, the movable ejection tray 35 is housed inside the image forming apparatus 100 .
On the other hand, the "auxiliary loading position" of the movable discharge tray 35 is located below the discharge port A (discharge section) and above the discharge tray 33 (placing section), where the sheet P discharged from the discharge port A is located. It is configured so that it can be placed. That is, when the movable discharge tray 35 is located at the auxiliary loading position (the position shown in FIG. 3(B), FIG. 4(B), etc.), the sheet P discharged from the discharge port A is not discharged. Instead of being placed directly on the tray 33, it is placed on the movable ejection tray 35 at a higher position than the ejection tray 33. In the present embodiment, when the movable ejection tray 35 is located at the "auxiliary placement position", the movable ejection tray 35 protrudes to the outside of the image forming apparatus 100 (above the ejection tray 33). be.

Here, the movable discharge tray 35 as a movable loading section has a generally horizontal loading surface that is substantially parallel to the loading surface of the output tray 33 (the surface on which the sheet P is placed). It is a plate-like member made of aluminum. The movable discharge tray 35 is formed with a certain degree of rigidity (plate thickness) so as to be able to hold the sheets P placed thereon.
The movable discharge tray 35 is moved in a substantially horizontal direction (in the left-right direction in FIG. 2) by a moving mechanism 85 controlled by the control section 90. As the moving mechanism 85, for example, a pinion rack mechanism or the like can be used.

The plurality of distance measuring sensors 71 and 72 cause the sheet P discharged from the discharge port A (discharge section) to curl in a concave shape in a direction opposite to the discharge direction (direction from right to left in FIG. 2). It functions as a curl detection means for detecting a downward curl state (a state in which the lower surface of the sheet P is bent in a concave shape as shown in FIG. 3(A)).
A plurality of distance measuring sensors 71 and 72 as curl detection means are arranged in parallel at intervals in the height direction between the discharge port A (discharge section) and the discharge tray 33 (placing section). Specifically, the second ranging sensor 72 is installed at a lower position than the first ranging sensor 71. Further, the two distance measuring sensors 71 and 72 are installed at a position higher than the discharge tray 33 and lower than the movable discharge tray 35. Moreover, the two distance measuring sensors 71 and 72 are installed in the main body exterior part 110 in which the discharge port A is formed.

The distance measuring sensors 71 and 72 are sensors that optically detect the distance to the object to be detected.
Therefore, as shown in FIG. 2, under normal conditions when the sheet P discharged from the discharge port A does not have a downward curl, the distance to the sheet P detected by the first distance measurement sensor 71 is different from the distance measured by the second distance measurement sensor 71. This distance is shorter than the distance to the sheet P detected by the sensor 72. Based on the detection results of the distance measuring sensors 71 and 72, the control unit 90 determines that the sheet P is not in a downward curl state.
On the other hand, as shown in FIG. 3A, when the sheet P discharged from the discharge port A is in a downward curl state, the sheet P detected by the first distance sensor 71 is does not become shorter than the distance to the sheet P detected by the second distance measurement sensor 72. Based on the detection results of the distance measuring sensors 71 and 72, the control unit 90 determines that the sheet P is in a downward curl state.

When the downward curl state is not detected by the range sensors 71 and 72 (curl detection means), the movable discharge tray 35 (movable placement section) is located at the retracted position and is moved to the retracted position. ), when the downward curl state is detected, the movement is controlled so that it is located at the auxiliary placement position.
Specifically, as shown in FIG. 3A, when the distance sensors 71 and 72 detect that the sheet P discharged from the discharge port A by the discharge roller pair 31 is in a downward curl state, the control unit 90 moves the movable discharge tray 35 from the retracted position shown in FIG. 3(A) to the auxiliary placement position shown in FIG. 3(B). This not only prevents the sheet P from curling due to the downward curling state, but also allows the sheet P to be placed on the movable discharge tray 35 in a state in which the curling caused by the downward curling state is corrected. This is because the movable ejection tray 35 is arranged near the bottom of the ejection port A, and the sheet P is ejected so that the leading edge of the sheet slides on the placement surface of the movable ejection tray 35 without curling downward. This is to move in the direction.

In particular, in this embodiment, the presence or absence of the downward curling state of the sheet P as described above is detected, and the operation of moving the movable ejection tray 35 from the retracted position to the auxiliary placement position when the sheet P is in the downward curled state is performed at the ejection port. This is performed every time a sheet P is discharged from A.
Specifically, after the sheet P (for which the downward curl state has been detected) is placed on the movable ejection tray 35, the movable ejection tray 35 is moved from the auxiliary placement position to the retreat position by the moving mechanism 85. do (return). As a result, the sheet P placed on the movable ejection tray 35 is released from being held by the movable ejection tray 35, and falls downward under its own weight onto the ejection tray 33 (the sheet P is already on the ejection tray 33). If it is placed, it will be placed on the uppermost sheet P, but in that case also it will be placed on the ejection tray.) At this time, the sheet P falling under its own weight has been corrected from curling due to the downward curling state and is in a fully stretched state, so that it is placed neatly on the discharge tray 33.

As described above, in the present embodiment, the presence or absence of the downward curl state of the sheet P is detected, and only when the downward curl state is detected, the movable discharge tray 35 is moved from the retracted position to the auxiliary loading position. Therefore, it is possible to efficiently reduce the problem of stacking defects in the sheets P placed on the discharge tray 33 without reducing the number of sheets P that can be stacked unnecessarily.
That is, when a downward curl occurs on the sheet P as shown in FIG. The sheets P may overlap each other in a buckled state on the ejection tray 33, or the sheet P on the ejection tray 33 may be pushed out by the next sheet P to be ejected and placed and fall from the ejection tray 33. A "stack failure" may occur.
On the other hand, in the present embodiment, the sheet P in the downwardly curled state is placed on the movable discharge tray 35 once, and then placed on the discharge tray 33 after the downwardly curled state is resolved. In addition, the sheet P without downward curl is directly placed on the discharge tray 33 as it is. Therefore, the occurrence of stacking defects due to the downward curling state can be reduced without reducing the number of sheets P stacked on the discharge tray 33 (the stacking height).

Here, referring to FIG. 1 and the like, the image forming apparatus 100 according to the present embodiment includes a temperature/humidity sensor 80 near the feeding device 12 in which the sheet P before image formation (before printing) is accommodated. is set up.
The temperature/humidity sensor 80 can function as a temperature/humidity detection means in the discharge device 30 to detect that the temperature/humidity inside the image forming apparatus main body 100 is in a high temperature/humid state. In that case, the movable discharge tray 35 (movable loading section) is located at the retracted position when the temperature and humidity sensor 80 (temperature and humidity detection means) does not detect a high temperature and high humidity state, and When this is detected, the movement is controlled so that it is located at the auxiliary placement position.
When the temperature and humidity environment inside the image forming apparatus 100 is high temperature and humidity, the moisture content of the sheet P increases and downward curl is likely to occur during discharge. It is possible to efficiently reduce the problem of stacking defects in the sheets P placed on the discharge tray 33 without reducing the number of sheets unnecessarily.

Specifically, when a high temperature and high humidity condition is detected by the temperature/humidity sensor 80, the sheet P discharged from the discharge port A by the discharge roller pair 31 tends to curl downward, as shown in FIG. 4(A). Under the control of the moving mechanism 85 by the control unit 90, the movable discharge tray 35 is moved from the retracted position shown in FIG. 4(A) to the auxiliary placement position shown in FIG. 4(B). As a result, even if the sheet P has a downward curl, the curling caused by the curling is not promoted, and the sheet P is placed on the movable discharge tray 35 in a state in which the curling caused by the downward curling has been corrected. It turns out.
Note that the operation of the ejection device 30 after the sheet P is placed on the movable ejection tray 35 is the same as that described above.

Here, the above-mentioned "high temperature and high humidity state" can be a state in which the relative humidity determined based on the temperature and humidity detected by the temperature and humidity sensor 80 is a predetermined value or more.
Specifically, when the relative humidity determined based on the temperature and humidity detected by the temperature/humidity sensor 80 is equal to or higher than a predetermined value, it is assumed that the sheet P has a high moisture content and is likely to curl downward, and the movable discharge tray 35 is moved from the retracted position to the auxiliary placement position.
Control using the temperature/humidity sensor 80 (temperature/humidity detection means) in this way is useful when the sheet P is ejected at high speed and the movable ejection tray 35 cannot be moved to the auxiliary placement position in time. .

Note that the movement control of the movable ejection tray 35 using the temperature/humidity sensor 80 (temperature/humidity detection means) and the movement control of the movable ejection tray 35 using the distance measuring sensors 71 and 72 (curl detection means) are both compatible. It can be configured to perform either one or the other.
Particularly, in the case where both movement controls are compatible, it is useful in the image forming apparatus 100 in which the discharging speed of the sheet P changes as the conveying speed of the sheet P is adjusted. That is, when the sheet P discharge speed is fast, the movement of the movable discharge tray 35 is controlled using the temperature and humidity sensor 80, and when the sheet P discharge speed is slow, the movable discharge tray 35 is controlled using the distance measuring sensors 71 and 72. The movement of the tray 35 will be controlled.
Although the temperature and humidity sensor 80 is installed near the feeding device 12 in this embodiment, it may be installed at any other position as long as it can detect changes in the moisture content of the sheet P.

Here, in the discharge device 30 according to the present embodiment, the first distance measurement sensor 71 (a plurality of distance measurement sensors 71 arranged in parallel at intervals in the height direction between the discharge port A and the discharge tray 33, 72) also functions as a height detection means for detecting the stacking height of the sheets P stacked on the discharge tray 35 (loading section).
Note that, assuming that the thickness of the sheet P is constant, the "stacked height" of the sheet P approximately corresponds to sheet thickness x number of sheets.
Furthermore, even if the sheet P is discharged from the discharge port A, the distance sensor 71 serving as a height detection means detects the sheet P up to that position when the detection result (distance to the sheet P) is constant and does not change. It is assumed that it is loaded. Specifically, when the output signal of the first distance measurement sensor 71 remains on and does not change, the control unit 90 determines that the sheets P are stacked up to the stacking height of the first distance measurement sensor 71.

In the present embodiment, the movable discharge tray 35 (movable loading section) is moved to the evacuation position when the loading height detected by the first ranging sensor 71 (height detection means) exceeds a predetermined value A. The movement is controlled so that it is located at .
That is, when the first distance sensor 71 detects that the sheets P are stacked up to the stacking height of the first distance sensor 71, the subsequent distance sensors 71, 72 (curl detection means) and temperature/humidity sensor 80 (temperature/humidity detection means), the movable ejection tray 35 is not moved from the retracted position to the auxiliary placement position, and the movable ejection tray 35 is maintained at the retracted position. This state continues until the state in which the sheets P are stacked up to the stacking height of the first distance measurement sensor 71 is resolved, such as by the user removing the sheets P stacked on the output tray 33. .

In this way, when the stacking height of the sheets P exceeds the predetermined value A, the uppermost sheet P among the plurality of stacked sheets P is the same as the movable discharge tray 35 located at the auxiliary stacking position. It will work like this. That is, even if the sheet P is in a situation where downward curl occurs, the leading edge of the sheet moves in the ejection direction as if sliding over the uppermost sheet P before the sheet P curls due to the downward curl. The sheets P are stacked in an orderly manner.
Furthermore, if the stacking height of the sheets P exceeds the predetermined value A, moving the movable output tray 35 to the auxiliary loading position may interfere with the sheets P stacked on the output tray 33. Therefore, by performing the above-described control, it is possible to prevent such problems from occurring.

FIG. 6 is a flowchart showing an example of movement control of the movable discharge tray 35.
As shown in FIG. 6, first, when the sheet P is discharged from the discharge port A, it is determined whether the downward curl state is detected by the distance measuring sensors 71 and 72 (step S1). At this time, it may be determined in advance whether a high temperature and high humidity state has been detected by the temperature and humidity sensor 80.
If it is determined in step S1 that the downward curl state (or high temperature and high humidity state) is not detected, no stacking failure will occur even if the sheet P is placed on the discharge tray 33 as it is. As a result, the movable discharge tray 35 remains retracted to the retracted position (step S3).
On the other hand, if it is determined in step S1 that a downward curl state (or a high temperature and high humidity state) has been detected, if the sheet P is placed on the discharge tray 33 as it is, a stacking failure will occur. As a result, the movable discharge tray 35 is moved from the retracted position to the auxiliary placement position (step S2). These controls are performed every time the sheet P is discharged from the discharge port A.
Then, it is determined by the first distance measuring sensor 71 whether the stacking height of the plurality of sheets P stacked on the discharge tray 33 has reached a predetermined value A (step S4). As a result, if it is determined that the loading height has reached the predetermined value A, it is assumed that the control for moving the movable discharge tray 35 from the retracted position to the auxiliary loading position is unnecessary, and the movable discharge tray 35 is The movable discharge tray 35 is set in a state in which it cannot be moved to the auxiliary placement position (a state in which the movable discharge tray 35 is maintained in the retracted position) (step S5).
On the other hand, if it is determined in step S4 that the loading height has not reached the predetermined value A, control to move the movable discharge tray 35 from the retracted position to the auxiliary loading position is performed as necessary. What must be done is to enable control of movement of the movable discharge tray 35 to the auxiliary placement position (step S6).

As described above, in the discharge device 30 according to the present embodiment, the discharge tray 33 (placing section) on which the sheet P discharged from the discharge port A (discharge section) can be placed is located below the discharge port A. It is located. Additionally, there is an auxiliary loading position below the discharge port A and above the discharge tray A where the sheet P discharged from the discharge port A can be placed, and a discharge tray 33 for the sheet P discharged from the discharge port A. A movable discharge tray 35 (movable loading section) is installed that can be moved between a retracted position that does not interfere with the loading of the tray. Further, a plurality of distance measuring sensors 71 and 72 (curl detection means) are installed to detect a downward curl state in which the sheet P discharged from the discharge port A curls concavely in a direction opposite to the discharge direction. The movable discharge tray 35 is located at the retracted position when the downward curl state is not detected by the plurality of distance measurement sensors 71 and 72, and is located at the auxiliary position when the downward curl condition is detected by the plurality of distance measurement sensors 71 and 72. The movement is controlled so that it is located at the desired position.
As a result, it is possible to efficiently reduce the problem of stacking defects in the sheets P placed on the discharge tray 33 (placement section) without reducing the number of sheets P that can be stacked unnecessarily.

Note that in this embodiment, the present invention is applied to the ejection device 30 installed in the monochrome image forming apparatus 100, but the present invention can naturally be applied to the ejection device installed in the color image forming apparatus. can be applied.
Further, in this embodiment, the present invention is applied to the ejection device 30 installed in the electrophotographic image forming apparatus 100, but the present invention is not limited to this, and the present invention can be applied to other types. The present invention can also be applied to a discharge device installed in an image forming apparatus (for example, an inkjet image forming apparatus, a stencil printing machine, etc.).
Further, in the present embodiment, the present invention is applied to the ejection device 30 from which the sheet P after image formation is ejected in the image forming apparatus 1, but the document conveyance device as the ejection device from which the original sheet is ejected is used. The present invention can also be applied to an apparatus (automatic document feeder).
Even in such cases, effects similar to those of this embodiment can be obtained.

Note that it is clear that the present invention is not limited to this embodiment, and that this embodiment can be modified as appropriate within the scope of the technical idea of the present invention in addition to what is suggested in this embodiment. be. Further, the number, position, shape, etc. of the constituent members are not limited to those in this embodiment, and can be set to a number, position, shape, etc. suitable for implementing the present invention.

Note that in this specification and the like, the term "sheet" is defined to include all sheet-like recording media such as coated paper, label paper, OHP sheet, metal sheet, etc. in addition to paper.

30 discharge device;
31 Ejection roller pair,
33 Ejection tray (loading section),
35 Movable discharge tray (movable placement section),
71 first distance sensor (curl detection means, height detection means),
72 second distance measurement sensor (curl detection means),
80 Temperature and humidity sensor (temperature and humidity detection means),
100 Image forming device (image forming device main body),
P sheet, A discharge port (discharge section).

Japanese Patent Application Publication No. 2013-112479

Claims (6)

a loading section disposed below the discharge section and capable of placing a sheet discharged from the discharge section;
an auxiliary loading position that is below the output section and above the loading section and can place the sheet discharged from the discharge section; and a auxiliary loading position where the sheet discharged from the discharge section can be placed on the loading section. a movable placement part that is movable between a retracted position that does not impede placement;
a curl detection means for detecting a downward curl state in which the sheet discharged from the discharge section curls in a concave shape in a direction opposite to the discharge direction;
Equipped with
The movable placement section is located at the retracted position when the curl detection means does not detect the downward curl state, and is located at the auxiliary placement position when the curl detection means detects the downward curl state. movement is controlled,
The ejecting device, wherein the curl detecting means is a plurality of distance measuring sensors arranged in parallel at intervals in the height direction between the ejecting section and the placing section . comprising a temperature/humidity detection means for detecting that the temperature/humidity inside the image forming apparatus main body is in a high temperature/humidity state;
The movable placing section is located at the retracted position when the high temperature and high humidity condition is not detected by the temperature and humidity detection means, and is located at the auxiliary placement position when the high temperature and high humidity condition is detected by the curl detection means. 2. The ejection device according to claim 1, wherein the ejection device is controlled to move so as to be located at . The temperature/humidity detection means is a temperature/humidity sensor installed near a feeding device in which the sheet before image formation is stored,
The discharge device according to claim 2, wherein the high temperature and high humidity state is a state in which relative humidity determined based on the temperature and humidity detected by the temperature and humidity sensor is a predetermined value or more. comprising a height detection means for detecting the stacking height of the sheets stacked on the loading section,
The movement of the movable loading section is controlled so that it is located at the retracted position when the loading height detected by the height detection means exceeds a predetermined value. 3. The discharge device according to any one of 3. A plurality of distance measuring sensors are provided in parallel at intervals in the height direction between the discharge section and the placement section,
The ejection device according to claim 4, wherein the height detection means is one of the plurality of distance measurement sensors. An image forming apparatus comprising the ejecting device according to any one of claims 1 to 5.

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