JPS5986552A - Device for detecting discharge of image bearing medium in imaging device - Google Patents

Abstract

PURPOSE:To obtain a device for detecting the discharge of an image bearing medium, which needs not exchange signals with a main imaging device in an electronic copying machine or the like, and which may always properly discriminate a change of originals even if the intervals of discharges of image bearing mediums vary upon change of originals. CONSTITUTION:A sorter 1 comprises a detector 6 for detecting a copying paper 4 on a conveying path 2, discharged from a main copying machine 3, a timer counter 12 for detecting a time interval of discharges of copying papers 4 each time a copying paper 4 being discharged, in association with a detection signal from the detector 6, a memory part 8 for storing the interval of discharges of copying papers 4, and a control part 11 for comparing the discharge time interval stored in the memory part 8 with the discharge time interval which is counted by the timer counter 12 each time a copying paper 4 being discharge, to discriminate a change of originals by the user. Accordingly, when, for example, a first original is replaced with a second one, a copying condition having a copying speed higher than that of the first original is set to the main copying machine 3 by the user, and the control part 11 surely discriminates the change of the originals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image medium ejection detection device in an image forming apparatus that detects an image medium ejected from the image forming apparatus.

[Technical background of the invention and its problems]

In order to control the operation of the Δ-additional device of the sorter used in the +t-ip manner in the image forming apparatus, it is important to determine whether or not a document has been replaced by the user in the image forming apparatus.

For example, a sorter as an additional device to an image forming apparatus may require a transmitting/receiving device to receive and pass signals to and from the image forming apparatus main body in order to determine whether to exchange originals in the image forming apparatus, or it may not require a transmitting/receiving device. There is something.

However, in the case where the above-mentioned transmitting/receiving device is required, the transmitting/receiving device itself becomes useless when the user uses only the image forming device without the need for a sorter. Further, there are disadvantages such as the structure of the sorter body becomes complicated due to the need for a zero feed device, and the attachment to the image forming apparatus body becomes troublesome.

Further, for example, a sorter of an electronic copying machine that does not require the above-mentioned transmitting/receiving device is a ram that detects image media (copies M) sequentially discharged from the electronic copying machine in order to determine whether to replace originals in the electronic copying machine.

Equipped with means of exit.

If the copy paper is not detected by the detection means even after a predetermined time T elapses, it is determined that the original has been replaced by the user, and a new collation operation is performed after the original is replaced. Here, the above-mentioned time T is the longest ejection time of copy paper since the ejection time interval of copy paper from the electronic copying machine varies depending on the copying conditions such as the size of the copy paper and the copying magnification. However, depending on the user's original exchange operations and copying conditions, the time interval is set to be a little longer than the original copy paper and the next new original. On the other hand, the ejection time interval with the copy paper ejected from the electronic copying machine for the first time may be shorter than the above-mentioned set time T.For this reason, in conventional sorters, it is difficult for the user to replace the original document. Therefore, there is a problem in that the collating operation is performed following the collating operation for the copy paper of the original original, and the correct collating operation may not be performed. .

[Purpose of the invention]

The present invention has been made in order to eliminate the above-mentioned problem, and it is possible to always correctly determine whether to replace the original even if the ejection time interval of the east delta body of the main body of an image forming apparatus such as an electronic copying machine is varied. It is an object of the present invention to provide an image medium ejection detection device for an image forming apparatus, which can perform all desired operation controls on additional devices of the image forming apparatus at all times.

At the same time, the detected discharge time interval is arbitrarily stored in a storage means, and the new discharge time interval by the second detection means is larger than the discharge time interval stored in the storage means. The means is configured to determine, for example, that a document has not been replaced by a user, and to control the operation of an additional device of an image forming apparatus. A detailed description will be given with reference to the illustrated embodiments.

FIG. 1 is a schematic sectional view showing an embodiment of the present invention. For example, a sorter (1) as an additional device of the image forming apparatus is connected to, for example, a copying machine main body (3) as an image forming apparatus via a conveyance path (2).

The conveyance path (2) carries copy paper (4) as an image medium inside the sorter (1), which is discharged to the outside of the copying body (3) by a paper discharge roller (3a) provided at the discharge port of the copying machine (3). A guide plate (Za) is provided between the copying machine main body (3) and the sorter (1), and a guide plate (Za) is provided at the end of the guide plate (Za) on the sorter (1) side. The O-sorter (1) is composed of a conveyor roller (2b).
Stacked 1 non-sort bin (5n) and 10 sorted bins (5z) + (52) l (5a)・
...(510). Non-sort bins (5~ are for storing all copy paper (4) in non-sort mode (two-tap use), and sort bins (
51) ... (51o) is for collating copy sheets in the sort mode (using sorter) 0 Figure 2 shows the control mechanism of the sorter (1), that is, the copy 42 is for the paper detection device. FIG. 3 is a block diagram showing the configuration. The control section (11) as a comparison means has a timer counter section (one timer counter section) as a second detection means and a memory section (11) as a storage means, '-! Carefully output part ← lc) (
A detector (6) as a first detection means, a roller (
1 remoter C2c), bin motor, and sorter mode (1 ton changeover switch) are connected to the detector (S) is installed in the middle of the conveyance path (2) and detects the passage of copy paper (4). outputs a detection signal to the control unit (11).The roller motor (2c) is for driving the conveyance roller (2b), and upon receiving the control signal from the control unit α1), rotates the conveyance roller (2b)' (r rotation). It is something that makes you

The bin motor (1a) is for driving non-sort bins (5n) and sort bins (51) (510), and receives control signals from the control unit (11) to drive stacked non-sort bins (5n) and sort bins (51). )...
・(510) (Non-sort bin (5n) and sorted bin (51)...(51o)k are simply bins (5
) are integrally moved up and down (arrows in Figures A and β 1) to make a predetermined bin face the conveying roller (b). The sorter mode changeover switch αb) is attached to the sorter (1) main body and is connected to the control unit (11).
This is to switch the operation control of the sorter (1) from non-sort mode to sort mode or from sort mode to non-sort mode, and outputs a mode switching signal to the control section (11). ) is a roller motor (2c)
mll Consists of a regular timer counter (12a) and a timer counter (12b) for controlling the bin motor.When the rear end of (4) is detected, it receives a signal from the control section (11) and starts counting. Start and then pass copy paper (4
), the counting is stopped at the same time as the tip of the copy paper is detected, and by repeating this operation, the paper ejection time interval is counted every time copy paper is ejected from the main body of the copying machine (3). be. In addition, in the embodiment, this timer counter (1
2b) is configured to issue an alarm in response to a command from the control unit α1) if the leading edge of a certain original copy paper (4) is not detected. The timer counter (12a) is the detector + regardless of sort mode or non-sort mode.
When g (3) detects the leading edge of the copy paper (4) passing through the transport path (2), it receives a signal from the control unit (11) and starts counting, and after a certain period of time T1, the control unit ( 11)
When this is determined, the counting is stopped, and when the detector (2) detects the leading edge of the next copy paper (4) before the elapse of a certain period of time T1, counting is restarted from O.

The storage unit (8) is a rewritable and readable storage area (8a
) and read-only storage (8b)'! i=has.

The storage area (8a) stores copy paper (4) (which passes through the conveyance path (2) first for a certain original in the sort mode).
The first copy paper (4)) and the next copy paper (2)
The time T3 obtained by adding a certain time t to the ejection time interval T2 (counted by the timer counter (12b)) of the copy sheet (4) is stored and rewritten every time the original is replaced.

Here, the time t is the time when multiple copies of one document are ejected from the copying machine (3) during the sort mode, and the number of copies is ejected from the conveyance path (2).
This is to absorb variations in the ejection time interval of all copy paper (4) that passes through. Further, the time T3 is read out by the control unit α1) every time the leading edge of the third or subsequent copy paper (4) for a certain original is detected by the easy-to-detect method.

On the other hand, the read-only storage area (8b) corresponds to the above-mentioned document from the error time data storage area, alarm time data storage area, roller motor drive time data storage area, and bin motor drive storage area. 1
The ejection time interval between the first sheet of copy paper (4) and the second sheet of copy paper (4) is counted by the timer counter (12b) and simultaneously read out by the control section (11). Alarm 7 The time data storage area stores the time screen o.
It is read out following the counting operation of the timer counter section (12b). Time TI is stored in the roller motor drive time data storage area and the bin motor drive time data storage area.
, T4 are stored, and the timer/counter α2a)
, (12b) are read out following the counting operation.

Next, regarding the operation of the sorter (1) configured as described above, FIG. 3 shows the control operation timing of the control unit (//).
This will be explained with reference to FIG.

The operation of the sorter (1) in the mass non-sort mode will be explained. In Figure 3, the mode changeover switch (1b
) is switched to non-sort mode by the user (
When the mode changeover switch (1b) is turned off), the control unit α1) receives this mode changeover signal from the mode changeover switch (1b) and starts control in the non-sort mode. That is, the control unit (11) sends a drive signal to the bin motor (1a) to rotate it. Therefore, the bin motor αa) moves the bin (5) completely downward (arrow A in Fig. 1) and rotates the non-sorted bean until it faces the conveyance roller (2h). When the copying switch (not shown) in 3) is turned on, a copying operation is performed in the copying machine (3), and the first copy paper (41) on which a copy image corresponding to a certain original is formed is delivered to the paper ejection roller (3a). is ejected from the main body of the copying machine (3) and sent to the paper feed path (2).At this time, when the tip of the first copy 7a (41) comes into contact with the actuator of the detector (6), When the detector (6) detects the leading edge of the copy paper), the detector (
6) operates and sends a detection signal to the control unit α1 until the copy paper (41) passes through the detector. (4th
When the controller (11) receives this detection signal, it sends a drive signal to the roller motor (2c) and also sends a fib operation signal to the timer counter (12a). Therefore, the conveyance roller (2b) rotates, and at the same time, the timer counter (12a) starts counting.

Further, when the timer color/return (12a) starts counting, the control section (11) reads the time data T1 from the storage section (8), and at a predetermined timing, reads out the time data T1 and the count amount T5 of the timer counter α2). Compare with. Then, the counted amount T5 of the timer counter (12a) is equal to the time T1.
If it exceeds this, a drive stop signal is sent to the roller motor C) to stop its rotation and also to stop the operation of the timer counter (12a). After this, when the detector (6) detects the leading edge of the next second copy fa (42), the control unit (11) again activates the roller motor (2).
c) and timer counter (12a) i operate. Also, the count T5 of the timer counter (12,) is the time T1
When the detector (6) detects the leading edge of the next second copy paper 42) before it exceeds f, the control unit α1) sends a new operation signal to the timer counter (12a) and
Start counting from 0. Below, the control part α1) is as follows:
The same operation control is performed each time the 4th sheet, 4th sheet, etc. of copy paper (4) comes in the feed path 1. Therefore, the roller motor (2)
Once the conveyance roller (2b) starts rotating, it rotates for a certain period of time T1, and before time N3T1 has elapsed, the leading edge of the next copy paper is detected by the detector (6). The rotation will continue. Therefore, when the copy paper (4) is conveyed near the conveyance roller (2b), the idle roller (b) is always rotating, and the copy paper (
4) is sent to and stored in the non-sort bin (5→) by this νa feed roller (26).The above is the sorter (
This is the effect of 1).

Next, the operation of the sorter (1) in the sort mode will be explained with reference to FIG.

The operation of the control unit α1) in the sort mode is controlled by the mode changeover switch (1b) in the same way as in the non-sort mode.
) is started when the control unit (11) receives a mode switching signal from the controller (11). In addition, in Fig. 6(b), the mode changeover switch (b) is initially in the non-sorting state, that is, the non-sorting bin (5n) is set to the transport roller (5n).
2b) In this case, when the mode changeover switch (lb) is switched to the sort mode by the user, the control section (11) receives a mode changeover signal from the mode changeover switch αb), rotates the bin motor (la)'e, and rotates the bin motor (la)'e. (5) Move kl bins upwards (arrow B in Figure 1).

Therefore, the first bin (51) placed at the top of the sorting bins (51)...(510>) faces the conveyance roller (2b).After this, as described above, the copying machine (3
) is operated by the user, the first sheet of copy paper (411) corresponding to the first document is fed to the conveyance path (2). The detector (6) detects this first copy paper (4
When detecting the tip of the controller (11), the detector (6)
1), and the control unit α1) receives this detection signal and rotates one conveyance roller (conveyance roller (2b)) in the same way as in the non-sort mode (λb).
The rotation control by the control unit (11) is the same as in the non-sort mode, so it will be omitted in the following explanation.)
0''!, when the first copy K (f-(4ti>) passes the detector (6) and the trailing edge of the copy paper (411) separates from the actuator of the detector (6) (detection vessel(
When the detector (6) detects the trailing edge of the copy paper (4lt), the detector (6) completely stops sending out the detection signal to the control unit α1).

When the sending of the detection signal from the detector (6) is stopped, in other words, the control unit α1) causes the copy paper (
411) When the rear end detection signal is sent, an operation signal is sent to the timer counter (12b), and the timer counter
Start counting (12b). Also, when the timer counter (12b) starts counting in this way, the control unit (
11) reads time data from the storage section (8) and compares this time data with the count value of the timer counter (12b) at a predetermined timing. and the control section (11
) determines that the count value of the timer counter α2b) has reached time T4, it sends a drive signal to the bin motor (la) to move the bin (5) upward by the e1 pin, and the second
The bin (52)' is made to face the conveyance roller (2b). 1
The second copy paper (41□) is the timer counter (12b)
is stored in the first bin (51) by the time T4 is counted. After this, the timer counter (12b) continues counting, and if the leading edge of the next second copy sheet is not detected by the detector (6) even if the counted value exceeds the entire time T7, the control is performed. The unit (11) determines that the user is copying one sheet at a time even though the user is in the sort mode, and stops the timer counter ← 2b) and generates an alarm, prompting the user to change the mode. Inform you that the settings are incorrect. Also, the timer counter (12b)
When the leading edge of the second copy paper is detected by the detector (6) before the count value exceeds time T7, the control (1ton control section 01) stops the timer counter 5A and turns O.
Second, the value T obtained by adding the time data t stored in the memory unit (8) to the count value T2 of the timer counter at that time.
3 is written to the storage area (8a). Next, when the detection (6) detects the trailing edge of the second copy paper G12), the control unit α1)
causes the timer counter (12b) to operate again.

Then, as in the case of the first copy paper (411), when the count value of the timer counter 02b) reaches time T4, 4, that is, the second copy #, (412) is transferred to the second bin (
52), the control unit (11) sends a drive signal to the bin motor (1a) to drive the bin (5) upward by one bin and move the third bin (53) to the transport roller (2b).
). Also, this rear rear α1) is the storage area (8
The value T3 written in a) is read out, and this value T3 is compared with the count value T2a f of the timer counter (2b) at a predetermined timing. And the timer counter
Before the count value T2a of (12b) reaches the value T3, the next 3
When the leading edge of the copy paper (413) is detected, the control unit α1) stops the counting operation of the timer counter (12b). Furthermore, when the rear end of the third copy paper (41a) becomes T4 by the detector (6), the fourth bin (54)
to face the conveyance roller. In addition, the second copy paper 3
The th copy paper (43) is also stored in the third bin (53) while the timer counter (12b) counts the time T4. The same operation control is repeated thereafter. In other words, the control unit (1
1) The rear edge of the first copy paper (41) is the detector (6)
The second copy paper after being detected by (42)
The time T until the tip of is detected by the detector (6)
, (first sheet of copy paper (4) and second sheet of copy paper (4)
2) and the discharge time interval with the timer counter (12b).
The time data t is counted at this discharge time interval T2.
, and the value T3 is stored in the storage area [F]a). After that, every time the third copy paper (43) passes the detector (6), the ejection time interval of the copy paper (4) is counted by the timer counter (12b), and the ejection time interval T2a is memorized. It is compared with the value T3 which is 1 written in area (8a). On the other hand, in the sort mode, the user makes two or more copies in succession using the copying machine main body (3). is discharged and passes through the detector (6). In addition, the above-mentioned fixed time T is determined by the timer counter (
12b) is approximately equal to the discharge time T2 of the second copy paper (42).

Therefore, 3 is counted by the timer counter (12b).
Unless the user replaces the original, the ejection time interval T for the subsequent copy sheets (4) should be smaller than the value T3, which is the sum of the time T2 and the time interval T3 to absorb variations in ejection time. be. Therefore, if the ejection time interval T2a of the third and subsequent copy sheets (4) for a certain original is longer than the value T3, in other words, the third and subsequent sheets of copy paper (2<K) After ☆: 1 paper is detected by the detector (6), and at the same time, the timer counter α2b) starts counting operation, and before the counted value reaches the value T3, +11th copy paper (4) is detected. If the leading edge of the second sheet of copy paper (412) is detected by the detector (6), it means that the document has not been replaced. The above-mentioned control unit α until the trailing edge of the third copy paper (43) is detected.
The operation control in 1) is repeatedly performed.

On the other hand, in FIG. 4, the rear edge of the i-th copy paper (41□) is detected by the detector (6) and the timer counter α2 is detected.
b) starts the counting operation, and even if the counted value reaches T3, if the leading edge of the i + 1st copy paper is not detected by the detector (6), the control unit ← 1) starts the counting operation at that point (timer counter ← 2).
When the count value in b) reaches T3, it is determined that the document has been replaced by the user. At the same time, the timer counter (12b) is stopped, the storage area (8a) is cleared, and the bin (5) is moved downward by one bin (arrow A in FIG. 1) to Place it opposite to the conveyor roller C?b). After that, the first copy i (5
21) is detected by the detector (6), the control unit α1) repeats the above-mentioned operation control in the same way. However, in this case, the direction of movement of the bottle (5) is downward (
In FIG. 1, it becomes arrow A).

Therefore, the last (i-th) copy paper (4) corresponding to this new document is stored in the first bin (51) (not shown), and after that, the i-th copy paper (42i) is stored in the first bin (51) (not shown). When the rear end is detected by the detector (6) and the count value of the timer counter (12b) which starts counting operation reaches T4,
Bin (5) is moved one bin down and becomes a non-sort bin (
The fifth season is opposed to the conveyance roller (2b). When the count value of the timer counter (02b) reaches T3, the control unit (11
) further determines new manuscript exchange. Also, as mentioned above, at this time, the timer roller (12b) is stopped, the storage area (8a) is cleared, the bin (5) is moved one bin upwards, and the first bin (51) is transferred to the conveyor roller ρb).
is faced with. When the copy paper (4) corresponding to the third original is ejected from the copying machine main body (3), the operation control described above (11) is repeated. In other words, when the control unit (11) determines that the original has been replaced, the operation control by the control unit (01) for the next original only changes the direction of movement of the bin (5), and the operations are performed sequentially each time the original is replaced. The same is repeated.

FIG. 5 shows, for example, a 3-page document (3 sheets) is transferred to the copying machine body (3) by a user in the sorter (1), which performs all the collating operations under the operation control of the control section (11) described above. When copying one copy at a time (when the number of collated copies is 3),
It shows the bin (5) in which each copy paper is stored, and the arrows in the figure indicate the collation order (the bin is placed on the transport roller (2b)
) and facing order). As shown in the figure, the first copy paper (411
) is the first copy paper (51), the second copy paper (412)
is stored in the second bin (52), and the fifth and final copy paper (4t5) is stored in the fifth bin (55). Also 2
△ Copy paper (421) corresponding to page (2nd) manuscript
(422), (423) + (42s) are stored in the reverse order of the 5th pin and the 4th bin, and are further stored on the 3rd page (3
Copy paper (431L (432
)...(43s) (Copy paper (4zz) corresponding to the 41st page original is stored in the same order.

On the other hand, when the fifth and final copy paper (43s) of the third page is stored in the fifth bin (55) and the use of the sorter is finished, the above-mentioned control unit (11)
Under the operation control, the sixth bead (5) is temporarily moved one bin down, and finally comes to be opposed to the fifth bead feed roller (2b). Therefore, when the sorter is used by the next second user in this state, if the number of sheets to be collated differs from the number of sheets to be collated by the first user, there will be an inconvenience. Regardless of whether the mode is used in sort mode or non-sort mode, first switch to non-sort mode by pressing the mode changeover switch ub>=. Then, the control unit (11) in the non-sort mode described above
During operation control, the non-sorting bin (5n) is opposed to the conveyance roller (2b). Therefore, if the second user uses the sorter in the sort mode, all he has to do is switch to the sort mode using the mode selector switch (lb) K, and if the second user uses the sorter in the non-sort mode, the state of 11 ( This is possible once the mode is switched to non-sort mode).

In addition, in this embodiment, the mode changeover switch (
1b) is switched to non-sort mode, bin (5
) is moved downward by a predetermined distance (a predetermined distance), and the non-note bin (5n) is placed opposite the transport roller (2b) K. When the sort mode is switched to, the bin (s) 75>+=
The first bin (51) is moved upward by a certain amount, and the first bin (51) is opposed to the feed roller. Furthermore, during the sorting operation of the sorter (1), the bins (5) are moved upward one by one each time copy paper corresponding to the first original is stored, and the bins (5) are moved upward one by one each time the original is replaced. As mentioned above, the direction is reversed. The movement of the bin (5) by the control unit (11) is controlled by, for example, providing a microsinch near the conveyance roller (2b) or in the direction of movement of the bin (da), and controlling the movement of the bin (5) every time the bin (5) is moved by one bottle. , △ or each time the non-sort bin (5n) is opposed to the conveyance roller, the control section (/l) is
A conventionally used technique, such as sending out a left stop signal, is sufficient, and is not the gist of the present invention, so a description thereof will be omitted.

As explained above, the sorter (1) in this embodiment is
A detector (6) as a first detection means for detecting copy paper (4) as an image medium discharged from the copying machine body (3) in the conveyance path (2), and detection from the detector (6). Copy paper ejection time interval detected by the timer counter (12) and timer counter ←2 as a second detection means that detects the ejection time interval every time 4 sheets of copy paper are ejected based on the signal. A storage unit (8) serves as a storage means for storing the ejection time interval of the copy paper (4) stored in the storage unit (8), and a new timer counter (12) counts each time the copy paper is ejected. A control unit αl) is provided as a comparison means for comparing the ejection time interval and determining whether the user should replace the document. In addition, in the sort mode, the copy paper corresponding to a certain document is ejected at regular intervals due to the continuous copying operation of two or more copies of the main body of the copying machine, so in this embodiment, the timer counter (12 ) is the value T3 which is the sum of the ejection time interval T2 of the first and second copy paper (4) corresponding to a certain document and a certain fixed time t (to absorb the ejection time interval). Storage part (8)
K is memorized, and based on this value T, the user can exchange the original 91 times.
The value T3 is counted again by the timer counter (12) and stored in the storage unit (8) each time it is determined by the cutting means φ control unit (11) that the document should be replaced. Therefore, the signal reception with the copying machine main body (3) does not need to be passed, and if the value of time t that absorbs the above-mentioned dispersion in the ejection time interval is appropriately selected, for example, from the first document to the second document. When replacing the original, the user sets the copying conditions in the copying machine main body (3) that the copying speed is faster than that for the first original, and the exchanging operation is performed quickly, reducing the ejection time of the copy paper. Even if the interval varies variously, the control unit (7) always reliably determines whether to replace the original.

For this reason, the sorter (1) is used as an additional device for the copying machine (3).
always performs the collating operation according to the user's wishes without malfunctioning.

Although this embodiment uses a sorter as an additional device of an image forming apparatus, the present invention is not limited to this. Further, the present invention can be modified in various ways without changing the gist thereof, such as being used to detect copy paper jams occurring in a copying machine.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to always correctly determine whether to exchange originals even if signals are received with the main body of the image forming apparatus without the need for handover. Desired operation control can always be performed on the device.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing a sorter (1) used in an embodiment of the present invention, FIG. △ A diagram showing the operation of the control mechanism in the sorting mode, FIG. 4 is a diagram showing the operation of the control mechanism in the sorting mode in the same example, and FIG. 5 is a diagram showing the collation order of the sorter (1) in the same example. . 1... Sorter, 3... Copy machine, 4... Copy paper,
5... Bin, 6... Detector, 8... Storage section, 11
...control section, 12...timer counter section. Agent Patent Attorney - Nori Kensuke Chika (and 1 other person) Figure 1 Figure 5 s'iL 7 2 Shin5ri5, f7

Claims (3)

[Claims] (1) A first detection means for detecting whether or not the image medium has been ejected from the image forming apparatus; and a second detection means for detecting the ejection time interval of the 52B body based on information from the first detection means. a detection means, a storage means for storing the discharge time interval detected by the second detection means, and a discharge time interval stored by the storage means and the discharge time newly detected by the second detection means. What is claimed is: 1. An image medium ejection detection device for an image forming apparatus, comprising: comparison means for comparing the interval. (2) The comparison means determines that the document has been replaced in the image forming apparatus when the direction of the ejection time interval newly detected by the second detection means is larger than the ejection time interval stored in the storage means. An image medium ejection detection device in an image forming apparatus according to claim 1, characterized in that:○ (3) The storage means stores the ejection time interval between the first image medium ejected from the image forming apparatus and the next ejected image medium for this original document every time the original document is replaced. An image medium ejection detection device in the image forming apparatus according to items 1 and 2.