JP2008265990A - Paper ejecting device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper ejecting device having a constitution capable of determining that paper different from a selected kind of paper is ejected. <P>SOLUTION: This paper ejecting device has a weight sensor 3 capable of detecting a weight change in an ejecting tray 5, a paper passing sensor 30 detecting the passing of the paper ejected to the ejecting tray 5, an operation part 101 capable of designating a kind of paper and the printing number, and a control part 100 connecting the weight sensor 3, the paper passing sensor 30 and the operation part 101 to the input side and connecting an alarm part 102 to the output side, and is characterized in that the control part 100 gives an alarm in the alarm part 102 in abnormal ejection, by determining whether ejection is normal ejection or the abnormal ejection by comparing loading weight acquired from the paper passing number from the paper passing sensor 30 with a detecting result from the weight sensor 3 based on a paper kind designated in the operation part 101. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sheet discharge apparatus and an image forming apparatus, and more particularly to a mechanism for determining a sheet discharge state.

  In an image forming apparatus such as a copying machine, a facsimile machine, a printer, or a printing machine, the image is transferred onto a sheet-like recording medium such as recording paper or an OHP film (hereinafter, a paper corresponding to a recording sheet will be described). The unfixed image carried is heated and fixed to obtain a copy or a printed output.

In general, a configuration is known in which sheets mounted in a sheet cassette or a sheet tray provided in the apparatus are sequentially fed out and fed toward a transfer position.
On the other hand, the sheet that has received the image transfer at the transfer position is discharged and stacked on the tray when the fixing is completed.

By the way, when the sheets discharged onto the tray are a plurality of print outputs, the sheets are sequentially stacked, but the sheet stacking state may be detected.
A typical example of detecting the stacking state of paper is the case of detecting the full state of the paper stacked on the tray. There is known a configuration in which a switch capable of abutting is provided and a full load state is determined by a stroke by which the switch is pushed up (for example, Patent Document 1).

JP-A-10-120295

  By the way, the paper discharged on the tray is fed in advance from a cassette or the like based on selection conditions desired by the user. However, the discharged paper may differ from the selected conditions, and the cause of this phenomenon is that paper of different types such as thickness and size is fed wrongly. It corresponds.

  Conventionally, as a method of determining the paper stacking state, there is a skew occurrence state in addition to the full load state described above, but there is almost no configuration for determining whether a different type of paper stacking has been performed. is there.

  An object of the present invention is to provide a paper discharge device having a configuration capable of determining abnormal paper discharge, in particular, a paper different from a selected type of paper, in view of the problems in the conventional paper discharge device. An object is to provide an image forming apparatus.

(1) A paper discharge device having a discharge tray capable of sequentially stacking discharged paper,
A weight sensor capable of detecting a change in weight of the discharge tray;
A paper passage sensor for detecting the passage of paper discharged to the discharge tray;
An operation unit capable of designating the type of paper and the number of prints, and a control unit in which the weight sensor, the paper passage sensor and the operation unit are connected to the input side, and an alarm unit is connected to the output side,
The control unit determines whether the discharge is normal or abnormal by comparing the loaded weight obtained from the number of paper passages from the paper passage sensor based on the paper type specified in the operation unit and the detection result from the weight sensor. A paper discharge device characterized in that an alarm is issued in the alarm unit when abnormal discharge is determined.

  (2) The control unit determines whether or not the paper thickness or the paper type is appropriate by comparing the difference between the loaded weight obtained from the number of paper passages and the detection result from the weight sensor with a specified value. (1).

  (3) The control unit determines that there is a discharge failure when there is no difference in the detection result from the weight sensor with respect to the loaded weight obtained from the number of passing sheets (1). Or the paper discharge apparatus as described in (2).

  (4) The control unit monitors two or more outputs of the weight sensor, determines that there is an abnormal discharge when only one weight sensor output different from normal occurs and then returns to normal. The paper discharge device according to any one of (1) to (3).

  (5) The control unit monitors two or more outputs from the weight sensor, and determines that the paper type is abnormal when two or more weight sensor outputs different from normal occur continuously (1). ) To (3).

  (6) A length detection sensor for detecting the length of the discharged paper is connected to the control unit, and when it is determined that the paper type is different, the detection result from the paper length detection sensor is appropriate. (2), it is determined that the paper thickness is inappropriate.

  (7) The control unit is connected to a length detection sensor that detects the length of the discharged paper. If it is determined that the paper type is different, the detection result from the paper length detection sensor is invalid. The paper discharge apparatus according to (2), wherein when it is appropriate, the paper size is determined to be abnormal.

  (8) The control unit is connected to a length detection sensor that detects the length of the discharged paper. When it is determined that the paper type is different, the detection result from the paper length detection sensor is appropriate. (5), it is judged that the paper thickness is inappropriate.

  (9) The control unit is connected to a length detection sensor for detecting the length of the discharged paper, and the detection result from the paper length detection sensor is invalid when it is determined that the paper type is different. The paper discharge apparatus according to (5), wherein when it is appropriate, the paper size is determined to be abnormal.

  (10) A paper width sensor for detecting the paper width is connected to the control unit, and if it is determined that the paper type of the paper is different, the thickness of the paper is determined as the detection result from the paper width sensor is appropriate. The paper discharge device according to (5), characterized in that it is determined to be abnormal.

  (11) When the paper width sensor for detecting the width of the discharged paper is connected to the control unit and it is determined that the paper type of the paper is different, the detection result from the paper width sensor is inappropriate. The paper discharge device according to (5), wherein the paper size is determined to be abnormal.

  (12) The control unit is connected to a paper length detection sensor and a paper width sensor for detecting the length and width of the discharged paper, and detects the paper length when it is determined that the paper type is different. The paper discharge apparatus according to (5), wherein when the detection results from the sensor and the paper width sensor are appropriate, it is determined that the paper thickness is abnormal.

(13) The control unit is connected to a paper length detection sensor and a paper width sensor for detecting the length and width of the discharged paper, and detects the paper length when it is determined that the paper type is different. The paper discharge device according to (5), wherein when the detection results from the sensor and the paper width sensor are inappropriate, the paper size is determined to be abnormal.
(14) The paper discharge device according to any one of (1) to (13), wherein a plurality of weight sensors are connected to the control unit to detect a change in weight of the discharge tray.

  (15) When the detection output from the weight sensor is decreased by a predetermined amount or more at a time, the control unit determines that the stacked sheets are removed from the discharge tray, and does not perform an alarm process ( The paper discharge device according to any one of 1) to (14).

  (16) The control unit according to any one of (1) to (15), wherein when the thickness, the paper type, and the size of the paper are determined to be abnormal, the contents are alarm-displayed. Paper discharge device.

  (17) An image forming apparatus using the paper discharge device according to any one of (1) to (16).

  According to the present invention, it is possible to determine the discharge state of a sheet only by using the detection of the passage of the sheet discharged to the discharge tray and the difference between the weight calculated from the number of passages and the actual weight. In particular, it is possible to prevent inadvertent abnormal discharge from continuing by issuing an alarm when a discharge state that does not meet the user's selection conditions occurs.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the embodiments shown in the drawings. FIG. 1 is a schematic diagram showing a configuration of an image forming apparatus using a paper discharge device according to the present invention.

  In FIG. 1, an image reading unit 21 that reads a document image is provided in the upper portion of the image forming apparatus and the housing 20, and the image reading unit 21 reads in the housing 20 in a lower portion adjacent to the image reading unit 21. A writing unit 22 for writing a document image is provided, and a photosensitive member 23 on which a document image is exposed by the writing unit 22 and a latent image of the document image is formed is arranged at a substantially central position in the housing 20. It is installed.

  A developing unit 24 that develops a latent image of a document image formed on the photosensitive member 23 into a toner image is disposed in close proximity to the peripheral surface of the photosensitive member 23, and the developing unit 24 is connected to the photosensitive member 23. Adjacent to the clockwise direction, a transfer unit 25 for transferring the toner image formed on the photoconductor 23 onto the transfer paper is disposed. Adjacent to the photoconductor 23, a fixing unit 17 for fixing the transfer paper is provided. It is arranged. Near the exit of the fixing unit 17, a pair of conveying rollers 28 for feeding the transfer sheet on which the fixing process has been performed is disposed, and a fixing unit that detects the transfer sheet that has been subjected to the fixing process is adjacent to the conveying roller pair 28 in the conveying direction. A paper discharge sensor (not shown) is provided.

  In the lower part of the housing 20, there are arranged a transfer paper cassette 26 in which transfer paper supplied to the transfer position is accommodated, and a double-sided transfer unit 7 that reverses the transfer paper that has been transferred on one side during double-sided transfer and supplies it to the transfer position. A manual paper feed tray 27 is attached to one side of the housing 20.

The paper discharge unit 1 corresponding to the paper discharge device in the present embodiment is provided on the other side of the housing 20 and discharges the paper to a position near the fixing paper discharge sensor (not shown) of the image forming apparatus. A transfer paper detection sensor 2 for detecting the transfer paper fed into the unit 1 is provided.
A pair of paper discharge rollers 4 for discharging the transfer paper is disposed adjacent to the transfer paper detection sensor 2 in the transfer paper transport direction, and the paper discharge unit 1 discharges paper on the side of the paper discharge unit 1. A paper discharge tray 5 for storing the transfer paper to be transferred is attached.

In the vicinity of the entrance of each paper discharge tray 5, a paper currency detection sensor 30 is provided as a paper passage means for detecting the transfer paper to be discharged, and a weight as weight detection means is provided on the bottom side of the paper discharge tray 5. A sensor 3 is arranged.
In this embodiment, the weight sensor 3 uses a load cell capable of detecting the weight of the paper discharge tray 5 and includes an actuator that contacts the bottom surface of the paper discharge tray 5 as shown in FIG.

  As shown in FIG. 3, when the weight sensor 3 is provided as a single unit, the weight sensor 3 is disposed at the center in the width direction of the paper discharge tray 5 (indicated by reference numeral P1 in FIG. 3) corresponding to the center in the width direction of the paper. In the case of a plurality of sheets, they are respectively arranged at positions (indicated by reference numerals P2 and P2 ′ in FIG. 3) that are equally divided with respect to the center in the width direction of the discharge tray 5. In addition, a plurality of paper passage detection sensors 30 are arranged at positions corresponding to the width of the paper in the paper width direction at positions where the paper is discharged to the paper discharge tray 5. In the case where a plurality of weight sensors 3 are provided, the weight sensor 3 can function when judging abnormal discharge such that the paper discharged from the center in the width direction is discharged from the center to one side.

As the weight sensor 3 used in this embodiment, a load cell capable of detecting the weight acting on the paper discharge tray 5 is used, and the arrangement shown in FIGS. 4 to 6 is appropriately selected as the arrangement configuration of the load cell. Is done.
In the arrangement shown in FIG. 4, a swing fulcrum 5A of the discharge tray 5 is provided on the upstream side in the feeding direction of the sheet fed from the pair of discharge rollers 4 with respect to the discharge tray 5 to support the discharge tray 5 so as to be swingable. The weight sensor 3 is arranged on the swing end side, and the arrangement shown in FIG. 5 is a sheet discharge tray on the downstream side in the feeding direction of the sheet fed from the sheet discharge roller pair 4 contrary to FIG. 5 is provided so that the paper discharge tray 5 is swingably supported, and the weight sensor 3 is disposed on the paper discharge roller pair 5 side which is the swing end side, and further shown in FIG. The arrangement configuration is such that the paper discharge tray 5 is supported so as to be movable up and down, and the weight sensor 3 is arranged at substantially the center position in the feed direction length of the paper fed from the paper discharge roller pair 4.

  FIG. 7 is a block diagram for explaining the configuration of the control unit used in this embodiment. The control unit 100 shown in FIG. 7 has a control panel 101 on the input side and a load as a configuration related to this embodiment. A weight sensor (shown as a load detection means in FIG. 7) 3 and a paper passage detection means 30 used as detection means and a paper passage detection means 30 are connected, and an alarm processing unit 102 is connected on the output side.

  The control unit 100 determines the weight of the paper loaded on the paper discharge tray 5 based on the paper type and the number of printed sheets designated on the operation panel 101, and the detection result from the weight sensor 3 serving as the load detection means. In contrast to this, the discharge state of the loaded paper is judged, and an alarm is given when abnormal discharge occurs.

  FIG. 8 is a diagram showing a standard used for determination of the discharge state executed in the control unit 100 shown in FIG. 7. In FIG. 8, the weight per sheet corresponding to the selected paper type is shown. The weight of the paper discharge tray 5 is proportional to the number of stacked sheets as a reference.

However, when the following weight change occurs, it is determined that the discharge has occurred.
In FIGS. 8A and 8B, the states indicated by (1) and (2) are cases where the change in weight assumed in the first discharge is different. In this case, the type of discharged paper is different. Is either when a sheet with a different thickness or size is discharged (a tendency indicated by an abnormality (1)) or when the discharged sheet slides from the stacking position (a tendency indicated by an abnormality (2)). It is judged.

The state indicated by (3) in FIG. 8 is a case where the weight decreases at a stretch during the stacking. In this case, the tendency of the increase in the weight up to that time may be a change of the number of stacked sheets with respect to the weight per sheet. For example, it is determined that the sheet group loaded by the user has been removed.
In the state shown in (4), as in (3), when the increase tendency of the weight is a change of the number of stacked sheets with respect to the weight per sheet, the increase is not observed at a certain point in time or the decrease tendency is In this case, it is determined that the sheets stacked up to that point and the discharged sheets have fallen from the discharge tray 5, and alarm processing is performed as a stacking abnormality.

  In the state shown in (5), the increase trend up to that time suddenly changes to an upward trend. In this case, it is determined that a load other than the stacking of the sheets has acted on the discharge tray. The load in this case corresponds to a case where the user presses the paper discharge tray 5 or a case where an object other than paper is placed on the paper discharge tray 5.

  Since the present embodiment is configured as described above, it will be described with reference to flowcharts showing the operation of the control unit 100 as shown in FIGS.

  In FIG. 9, in the discharge abnormality determination processing, the passage detection of the leading edge and the trailing edge of the sheet sent to the sheet discharge tray 5 is performed by the sheet passage detection means 30 (ST1, ST2), and the sheet is discharged to the sheet discharge tray 5. Is determined.

When the paper is sent out to the paper discharge tray 5, it is determined by the weight sensor 3 whether or not a weight change has occurred due to the stacked paper (ST3).
If the change in weight corresponds to the increase obtained from the paper type designated on the operation panel 101 in step ST3, it is determined that normal discharge has been performed (ST4), and this determination is repeated until the end of the job. (ST5). The job end in this case means the time point when the image formation for the number of prints designated on the operation panel 101 (see FIG. 7) is completed.

  If the increase in weight change does not correspond to the designated paper type in step ST3, it is determined that the paper is abnormally discharged (ST6), and alarm processing is performed (ST7). The alarm processing in this case corresponds to displaying an alarm on a display unit provided on the operation panel 101, and the alarm to the user can be recognized by the display.

  The process shown in FIG. 9 is a process when the weight change indicated by the solid line in FIG. 8 is targeted. Note that, in the drawings after FIG. 10, the same reference numerals as those shown in FIG.

In the abnormal discharge determination process shown in FIG. 10, a case where the paper type of the paper is different from that selected as the paper discharge abnormality is determined.
In FIG. 10, after the passage of the leading edge of the paper is detected (ST1, ST2), a change in weight after the discharge of the paper is determined, and when it is determined that there is almost no change in weight, an abnormal discharge is determined and an alarm process is performed. (ST8, ST6, ST7). The change in weight in this case means an increase in weight, and the case where the weight does not increase corresponds to the case where the discharged paper falls from the paper discharge tray. Is also judged as abnormal discharge.

  On the other hand, if it is determined in step ST8 that there is a change in weight, the change, in this case, an increase (indicated in the figure as increment) is set in advance corresponding to the paper type. It is determined whether it is within the increase range (ST9). The increase range in this case corresponds to the weight per sheet obtained by the thickness and size depending on the paper type selected on the operation panel, and a range including a detection error is set.

  In step ST9, if it is within the increase range, it is determined that the paper is normally discharged and the determination process is repeated until the end of the job. On the other hand, if it is determined that it is not within the increase range, the type of discharged paper is selected. An alarm process is performed by determining that the paper type is different (ST10). The paper type abnormality in this case corresponds to a case where the thickness of the discharged paper is different from the selected one. If the paper sizes are different, the length and width in the discharge direction out of the sizes can be used as a criterion for detecting the passage of the leading and trailing edges of the paper. The thickness of the target. Further, the determination of the discharge abnormality regarding the paper size will be described later.

In the abnormal discharge determination process shown in FIG. 11, the abnormal discharge determination process shown in FIG. 10 determines the sheets discharged to the discharge tray 5 in units of one sheet, but the determination is made for two sheets. It is supposed to be. The reason for this is to determine whether or not there is an abnormal discharge during the discharge when the continuous discharge is performed.
In FIG. 11, after detecting the passage of the leading end of the discharged paper, a change in weight is determined. If the increase is within the range, it is determined that the paper is normally discharged (ST1 to ST9).

On the other hand, when the increase in the weight of the discharged paper is not within the range, the subsequent paper discharge state is determined to determine the cause of abnormal discharge.
In FIG. 11, when the determination result of the weight increase in step ST9 is not within the predetermined range, the change in the weight is determined (ST9A) after detecting the leading edge passage detection (ST1A, ST2A) of the succeeding paper (ST9A). If it is within the predetermined range, it is determined that the previously ejected paper is not properly stacked, that is, it has fallen from the paper discharge tray, and an alarm process is performed (ST6A, ST7). It is determined that the paper type of the discharged paper is different from the selected one (ST10A), and as shown in FIG. 12, a different object regarding the paper type is determined.

  In FIG. 12, in the paper type discrimination, the paper length is determined based on the detection of the leading edge and the trailing edge of the paper based on the output from the paper passage sensor (ST11). If the length matches the selected paper, the paper type is detected. It is determined that the thickness is different from the selected one (ST12). If the paper length does not match the selected paper, it is determined that the paper size is different (ST13), and alarm processing is performed (ST7). .

  FIG. 13 shows another embodiment of the paper type discrimination process shown in FIG. 12, in which the paper width is detected by the paper passage sensor (ST14) and the paper type is discriminated. It has become. That is, the paper passage detection sensor 30 (see FIG. 3) detects the width of the paper passing through and detects the length of the passage time between the front and rear ends (ST14, ST11A).

  If the paper width or paper length is not appropriate in steps ST14 and ST11A, it is determined that the paper size is abnormal (ST13). If the paper width and paper length are appropriate, the paper thickness is determined based on the result of the weight change. It is determined that there is an abnormality (ST12). In either case, alarm processing is performed (ST7).

  The discharge abnormality determination process shown in FIG. 14 is a process for the case where a plurality of weight sensors 3 are provided (arrangement indicated by reference numerals P2 and P2 'in FIG. 3) as shown in FIG. In this case, it is possible to determine the discharge state of the sheet for the unbalanced sheet by determining whether the output from each weight sensor is the same. In other words, it is assumed that the center reference discharge state cannot be obtained due to some trouble when the paper is discharged in a state in which the center in the width direction and the center in the width direction of the discharge tray coincide with each other in a normal conveyance state. Also in this case, the discharge state of the selected sheet is determined.

  In FIG. 14, after the leading edge of the paper is detected (ST1, ST2), the outputs (c, d) between the weight sensors 3 are determined (ST14). In the determination in step ST14, if the outputs of the weight sensors are the same, it can be determined that the paper is not biased, and it is determined that the paper is in an appropriate discharge state (ST15).

  On the other hand, if the outputs of the weight sensors are different in step ST3, it is determined that the paper is biased and the discharge state is not appropriate, and an alarm process is performed (ST16).

  Thus, it is possible to determine abnormal discharge corresponding to a discharge state different from the center standard, which is one of the states that should be discharged.

It is a schematic diagram for demonstrating the structure of the image display medium formation apparatus using the paper discharge apparatus by the Example of this invention. It is a schematic diagram for demonstrating the basic composition of the weight detection mechanism used for the paper discharge apparatus by this invention Example. FIG. 3 is a schematic plan view for explaining an arrangement configuration of a weight sensor and a paper passage detection sensor used in the paper discharge device shown in FIG. 2. FIG. 3 is a schematic diagram for explaining an example of a configuration of a weight sensor and a paper discharge tray in the paper discharge device shown in FIG. 2. FIG. 5 is a schematic diagram for explaining another example of the configuration of the weight sensor and the paper discharge tray illustrated in FIG. 4. FIG. 6 is a schematic diagram for explaining another example of the configuration of the weight sensor and the paper discharge tray shown in FIG. 5. It is a block diagram for demonstrating the structure of the control part used for the paper discharge apparatus shown in FIG. It is a diagram showing the weight change and abnormal state for demonstrating the control reference | standard used by the control part shown in FIG. It is a flowchart for demonstrating one of the effects | actions performed by the control part shown in FIG. It is a flowchart for demonstrating another example of the effect | action performed by the control part shown in FIG. It is a flowchart for demonstrating the other example of the effect | action performed by the control part shown in FIG. 12 is a flowchart for explaining a subroutine executed in the flowchart shown in FIG. 11. FIG. 8 is a flowchart for explaining yet another example of the action executed by the control unit shown in FIG. 7. FIG. FIG. 10 is a flowchart for explaining still another example of the action executed by the control unit shown in FIG. 7. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper discharge unit 3 Weight sensor 5 Paper discharge tray 30 Paper passage detection sensor 100 Control part 101 Operation panel 102 Alarm processing part

Claims (17)

A paper discharge device having a discharge tray capable of sequentially stacking discharged paper,
A weight sensor capable of detecting a change in weight of the discharge tray;
A paper passage sensor for detecting the passage of paper discharged to the discharge tray;
An operation unit capable of designating the type of paper and the number of prints, and a control unit in which the weight sensor, the paper passage sensor and the operation unit are connected to the input side, and an alarm unit is connected to the output side,
The control unit determines whether the discharge is normal or abnormal by comparing the loaded weight obtained from the number of paper passages from the paper passage sensor based on the paper type specified in the operation unit and the detection result from the weight sensor. A paper discharge device characterized in that an alarm is issued in the alarm unit when abnormal discharge is determined.   The control unit determines whether or not a paper thickness or a paper type is appropriate by comparing a difference between a loaded weight obtained from the number of passing sheets and a detection result from the weight sensor with a specified value. Item 2. The paper conveyance device according to Item 1.   3. The control unit according to claim 1, wherein the control unit determines that the discharge is defective when there is no difference in the detection result from the weight sensor with respect to the loaded weight obtained from the number of passing sheets. The paper discharge device described.   The control unit monitors two or more outputs of the weight sensor, and determines that there is a discharge abnormality when only one weight sensor output different from normal occurs and then returns to normal. The paper discharge device according to any one of 1 to 3.   The control unit monitors two or more outputs of the weight sensor, and determines that the sheet type is abnormal when two or more weight sensor outputs different from normal occur continuously. The paper discharge device according to any one of the above.   When the length detection sensor that detects the length of the ejected paper is connected to the control unit, and the detection result from the paper length detection sensor is appropriate when it is determined that the paper type is different The paper discharge device according to claim 2, wherein the paper thickness is determined to be inappropriate.   The control unit is connected to a length detection sensor that detects the length of the discharged paper, and the detection result from the paper length detection sensor is inappropriate when it is determined that the paper type is different. The paper discharge apparatus according to claim 2, wherein the paper size is determined to be abnormal.   When the length detection sensor that detects the length of the ejected paper is connected to the control unit, and the detection result from the paper length detection sensor is appropriate when it is determined that the paper type is different 6. The paper discharge apparatus according to claim 5, wherein the paper thickness is determined to be inappropriate.   The control unit is connected to a length detection sensor that detects the length of the discharged paper, and the detection result from the paper length detection sensor is inappropriate when it is determined that the paper type is different. The paper discharge device according to claim 5, wherein the paper size is determined to be abnormal.   A paper width sensor for detecting the paper width is connected to the control unit, and if it is determined that the paper type is different, the thickness of the paper is abnormal if the detection result from the paper width sensor is appropriate. The paper discharge device according to claim 5, wherein the paper discharge device is determined.   The control unit is connected to a paper width sensor that detects the width of the ejected paper. If it is determined that the paper type of the paper is different, the paper size is detected when the detection result from the paper width sensor is inappropriate. The paper discharge device according to claim 5, wherein the paper discharge device is determined to be abnormal.   A paper length detection sensor and a paper width sensor for detecting the length and width of the discharged paper are connected to the control unit, and when it is determined that the paper type is different, the paper length detection sensor and the paper 6. The paper discharge apparatus according to claim 5, wherein when the detection result from the width sensor is appropriate, it is determined that the thickness of the paper is abnormal.   The control unit is connected with a paper length detection sensor and a paper width sensor for detecting the length and width of the discharged paper. When it is determined that the paper type is different, the paper length detection sensor and the paper The paper discharge device according to claim 5, wherein the paper size is determined to be abnormal when the detection result from the width sensor is inappropriate.   14. The paper discharge device according to claim 1, wherein a plurality of weight sensors are connected to the control unit to detect a change in weight of the discharge tray.   2. The control unit according to claim 1, wherein when the detection output from the weight sensor decreases by a predetermined amount or more at a time, the control unit determines that the stacked sheets are removed from the discharge tray and does not perform an alarm process. The paper discharge device according to any one of 14.   16. The paper discharge device according to claim 1, wherein the control unit displays a warning when the thickness, paper type, and size of the paper are determined to be abnormal.   An image forming apparatus using the paper discharge device according to claim 1.

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