JPH10120245A - Paper feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of part items of mechanism for detecting the quantity and presence of paper. SOLUTION: In case of a small quantity of paper P, the position fluctuation of a member 30 is not restrained by a member 40 rotated in the direction of an arrow mark C following a roller 21 installed at a stacking plate 20, so that an optical path 16A of light detected by a sensor is not intercepted by the member 30 at the time of not feeding paper but intercepted only at the time of feeding paper. In case of a large quantity of paper, the position fluctuation of the member 30 is restrained by a protruding part 41 of the member 40, the optical path 16A is not intercepted by the member 30 in either case of feeding or not feeding paper. The light detected result of the sensor is therefore changed by the quantity and presence of paper, so that both the quantity and presence of paper can be detected by one sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a paper feeder,
More specifically, the present invention relates to a sheet feeding device for sequentially feeding sheets stacked on a sheet stacking plate to an image forming apparatus.

[0002]

2. Description of the Related Art Generally, when using an image forming apparatus using cut paper such as a copying machine, a facsimile machine, a printer, etc., it is necessary to pay attention to the remaining amount of paper and replenish the paper immediately when the paper runs out. There is. However, in an image forming apparatus connected to a network such as a local area network (LAN), which has recently become widespread, an operator is not always located near the image forming apparatus. Therefore, in order to prevent the image forming apparatus from becoming inoperable due to paper shortage, when the remaining amount of the paper becomes equal to or less than a predetermined amount, the operator is required to provide the paper on a display such as a personal computer connected to the network. It is necessary to notify the operator that the paper is about to run out, and have the operator replenish the paper.

Conventionally, as a mechanism for detecting that the remaining amount of paper is less than a predetermined amount, Japanese Patent Application Laid-Open Nos. Sho 63-218453 and Hei 5-4715 follow the position of a sheet stacking plate. A technique is disclosed in which an actuator member is provided and a mechanism is provided in which the actuator member outputs a different signal to one sensor (or switch) when the remaining amount of paper becomes equal to or less than a predetermined amount. I have.

In general, in order to detect the presence or absence of a sheet, as described in JP-A-5-4715,
The actuator (following the paper position on the paper stacking plate) drops into the slit provided on the paper stacking plate when the paper runs out, so that a sensor (or switch) different from the above is different from when there is paper. A mechanism for outputting a signal is provided.

In the conventional system described above, a sensor (or a switch) for detecting whether or not the remaining amount of paper is smaller than a predetermined amount (a small amount of paper) is provided in a paper feeding device constituting the image forming apparatus. Both sensors (or switches) for detecting the presence / absence of paper are required. This has been a bottleneck in reducing the number of components of the entire image forming apparatus.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problem, and a paper feeder capable of reducing the number of parts of a mechanism for detecting the amount of paper and the presence or absence of paper. The purpose is to provide.

[0007]

According to a first aspect of the present invention, there is provided a sheet feeding device for sequentially feeding sheets stacked on a sheet stacking plate to an image forming apparatus. Detecting whether or not the number of sheets loaded on the sheet stacking plate is larger than a predetermined reference amount (a small number of sheets) and the presence or absence of the stacked sheets by the same sensor. I do.

According to a second aspect of the present invention, in the paper feeding apparatus according to the first aspect, the sensor detects a small amount of paper during paper feeding and detects the presence or absence of paper during non-paper feeding. It is characterized by the following.

According to a third aspect of the present invention, the paper feeder sequentially rotates the half-moon rolls in one direction in a unit of one rotation, thereby sequentially forming images on the paper stacking plate urged upward. A sheet feeding device for feeding the device, an optical sensor for detecting light passing through a predetermined optical path, and an upper and lower surface of the sheet against the urging force in cooperation with the rotation of the half-moon roll during sheet feeding. The first that interrupts the optical path of the optical sensor with the movement
Moving between the first position and the second position retracted from the optical path.
And the first actuator member is held at the second position when the sheet is larger than a predetermined reference amount, and when the sheet is smaller than a predetermined reference amount, the first actuator member is held at the second position. And a second actuator member for releasing the holding of the first actuator member.In the state where the holding is released, the first actuator member is configured to perform the second operation when there is no sheet and when there is a sheet at the time of feeding. 1 and moves to the second position when there is a non-fed sheet.

According to a fourth aspect of the present invention, in the paper feeder of the third aspect, the second actuator member is disposed so as to follow the position of the sheet stacking plate. Features.

According to a fifth aspect of the present invention, there is provided the paper feeding device according to the third aspect, further comprising a paper cassette mounting portion, wherein the paper cassette is removed from the mounting portion or the paper cassette is mounted. When attached to the first, the first
Is reset to a state held by the second actuator member.

According to a sixth aspect of the present invention, in the paper feeding apparatus according to the third aspect, it is determined whether the number of sheets is larger than a predetermined reference amount based on a result of light detection by the optical sensor. It is characterized by further comprising a judging means for judging the presence / absence of a sheet, and a notifying means for notifying the judgment result.

According to a seventh aspect of the present invention, there is provided the sheet feeding apparatus according to the sixth aspect, further comprising:
Detecting means for detecting at least one of whether or not the paper cassette has been removed from the mounting portion and whether or not the power has been turned off, and when it is detected that the paper cassette has been removed or the power has been turned off. The information of the result of the determination is reset.

According to an eighth aspect of the present invention, in the paper feeder according to the first or third aspect, the number of sheets from when the number of sheets becomes equal to or less than a predetermined reference amount to when the sheets are exhausted is counted. It is characterized by further comprising counting means.

According to a ninth aspect of the present invention, there is provided a sheet feeding apparatus having at least two sheet stacking units, and sequentially feeding sheets from each sheet stacking unit to the image forming apparatus. Paper amount detecting means for detecting whether or not the number of sheets loaded on a sheet is larger than a predetermined reference amount (a little amount of sheets); and determining whether or not detection of some sheets is valid or invalid for each sheet loading section. A setting unit for setting whether to perform the setting, and a storage unit for storing the set information in a nonvolatile memory.

In the paper feeder according to the first aspect, it is determined whether or not the number of sheets stacked on the sheet stacking plate is larger than a predetermined reference amount (a small number of sheets), and whether or not the stacked sheets are present. Are detected by the same sensor. More specifically, the sensor is configured such that the sensor detects the amount of paper during paper feeding and detects the presence or absence of paper during non-paper feeding.

As a sensor for detecting the presence or absence of the sheet and the amount of the sheet, an optical sensor can be used as in a sheet feeding device described in claim 3 described later. In addition, using a contact type switch other than the optical sensor, the switch is used in three cases: when there is paper and the amount is larger than a predetermined reference amount; when there is paper and the amount is equal to or less than the predetermined reference amount; If it is configured to switch, the function as the sensor of the present invention is achieved.

According to a third aspect of the present invention, there is provided a sheet feeding apparatus for sequentially rotating the half-moon roll in one direction in a unit of one rotation so as to sequentially print sheets stacked on a sheet stacking plate urged upward. And has an optical sensor for detecting light passing through a predetermined optical path.

Further, in the paper feeder according to the third aspect, the first path for blocking the optical path of the optical sensor in accordance with the rotation of the half-moon roll at the time of paper feed and the vertical movement of the upper surface of the paper against the urging force. A first actuator member is provided for moving between the position and a second position retracted from the optical path.

However, when the number of sheets is larger than the predetermined reference amount, the first actuator member is held at the second position by the second actuator member and does not move to the first position.

On the other hand, when the amount of paper falls below a predetermined reference amount,
The holding of the first actuator member by the second actuator member is released. The first actuator member, whose holding has been released, moves to the first position when there is no paper and when there is paper at the time of paper feeding (however, when the paper is less than a predetermined reference amount), and moves to the first position when paper is not fed. Move to the second position when there is a sheet of paper (however, the sheet is equal to or less than a predetermined reference amount).

If the second actuator member is arranged so as to follow the position of the sheet stacking plate, for example, as in the fourth aspect of the present invention, the second actuator member may be used when the number of sheets exceeds a predetermined reference amount. The operation (holding and releasing the first actuator member) that is different from that described above can be switched between the above cases.

For example, if a predetermined detection signal is output from the optical sensor only when light is detected by the optical sensor (that is, the sensor output signal is turned on),
The output signal from the optical sensor changes as shown in Table 1 below depending on the presence or absence of a sheet and the amount of the sheet. The ON state of the sensor output signal is "ON" and the OFF state is "OFF".
It was written.

[0024]

[Table 1]

As described above, one sensor (optical sensor) can detect both the presence or absence of a sheet and the amount of the sheet. This makes it possible to reduce the number of components of the mechanism for detecting the amount of paper and the presence / absence of paper, thereby reducing the cost of the apparatus.

In a paper feeder having a paper cassette mounting portion and a structure in which the paper cassette is mounted, when the paper cassette is once removed and then mounted, the paper is replenished and becomes larger than a predetermined reference amount. Could be. Therefore, when the paper cassette is detached from the mounting portion or when the paper cassette is mounted on the mounting portion, the first actuator member is held by the second actuator member. It is desirable to control so as to reset the state.

In the paper feeder according to the sixth aspect, based on the result of light detection by the optical sensor as described above, the determination means determines whether or not the paper is larger than a predetermined reference amount (a little paper). And the presence or absence of a sheet, and the notifying unit notifies the determination result. As the notification means, a message may be displayed on a display, a notification may be made by voice from a speaker, or the message may be printed on paper and output. Further, these may be executed in combination.

In the paper feeder according to the present invention, if the paper cassette is removed from the mounting portion or if the power is turned off, there is a possibility that the paper has been replenished. As in the present invention, it is desirable to reset the information of the determination result.

According to the present invention, the number of sheets and the presence / absence of sheets are determined by a single sensor, and a counting means is provided according to the invention described in claim 8. By counting the number of sheets from when the number of sheets becomes equal to or less than the predetermined reference amount to when the sheets are exhausted, it is possible to detect how many sheets are actually determined to be equal to or less than the reference amount. For example, by taking the average value of the number of sheets over several times and comparing it with a predetermined reference amount, it is possible to inspect whether or not the sheet is properly judged in the sheet feeding device.

By the way, as in the invention according to claim 9,
In a sheet feeding device having at least two sheet stacking units and sequentially feeding sheets from each sheet stacking unit to the image forming apparatus, the sheet stacking unit detects the number of sheets stacked on each sheet stacking unit by a predetermined reference amount. It is possible to detect whether the number is larger than the number of sheets (some paper). Here, the setting unit sets, for each sheet stacking unit, whether to enable or disable the detection of some of the sheets, and stores the set information in the non-volatile memory by the storage unit. Some detection can be made optional for each sheet stacking unit. For example, a sheet stacking unit that detects a small amount of sheets can be selected from a plurality of sheet stacking units as needed.

[0031]

Embodiments of the present invention will be described below. FIG. 1 shows a laser beam printer 50 as an example of an image forming apparatus to which the sheet feeding device of the present invention is applied.

As shown in FIG. 1, the paper P is fed from the paper stacking section Q1 by the main body feeding roll 1, from the paper stacking section Q2 by the cassette feeding roll 2, and from the paper stacking section Q3 by the cassette feeding roll 3. Each is fed. Paper P
The posture of the transfer roller 5 is corrected by the registration roll 4 and is conveyed to a contact portion (transfer nip) between the transfer roll 5 and the photosensitive drum 7 at a predetermined timing. On the photosensitive drum 7, an electrostatic latent image is written by a light beam from a laser scanner 8 inside the image forming unit 6, and the electrostatic latent image is developed to form a toner image. The toner image on the photosensitive drum 7 is transferred to the sheet P conveyed to the transfer nip by the transfer roll 5, and the toner image is placed on the surface of the sheet P. The sheet P is transported to the fixing roll 9, and the toner image is fixed on the sheet P by the fixing roll 9. The paper P on which the toner image is fixed is discharged by the discharge roll 10.

FIG. 2 shows, as an example of a sheet feeding device according to the present invention, a sheet feeding device 60 using a cassette sheet feeding roll 2 provided in a sheet stacking section Q2. The paper cassette 11 includes
The sheet stacking plate 20 is pivotally supported, and a spring 51 (see FIG. 3) applies an upward sheet feeding pressure in FIG. The main frame 12 has a toothless gear 1 supported by the same shaft.
3 and a half-moon-shaped cassette feeding roll (hereinafter, referred to as a half-moon roll) 2 are provided. Also, body frame 1
2, a photo sensor 16 including a light receiving element and a light emitting element is provided. Note that a slit 20A is provided at a predetermined position on the upper surface of the sheet stacking plate 20.

As shown in FIGS. 2, 5 and 6, one end of the body frame 12 is in contact with the upper surface of the paper P, and the other end is a light beam of the photo sensor 16 (the optical axis 16A is shown in FIGS. 5 and 6). Show)
The first actuator member 30 is arranged so as to vary between a position where the light is blocked (the position in FIG. 6) and a position where the light is not blocked (the position in FIG. 5). Furthermore, body frame 1
2, a second actuator member 40 that follows the movement of the rollers 21 provided on the sheet stacking plate 20 is installed.

As shown in FIGS. 2, 5, and 9, the rotation of the drive gear 18 is started by the rotation of the main motor (not shown). In the case where it is located at a position opposing to 18, the rotational driving force is not transmitted to the half-moon roll 2. Based on a paper feed start signal from a control unit 70 (see FIG. 10) of the paper feed device 60 described later,
A predetermined voltage is applied to the solenoid 14 and the solenoid 1
The locking member 14A provided on the gear 4 moves leftward in FIG. 9, and the locking claw 13B provided on the toothless gear 13 is released. Along with this release, the toothless gear 13 rotates in the direction of the arrow G by the spring 15, the bar-shaped member 38 and the cam 37, the drive gear 18 and the toothless gear 13 mesh, and the rotational driving force is transmitted to the half-moon roll 2. The rotatably driven half-moon roll 2 feeds one sheet at the top of the sheet stacking plate 20, and the fed sheet P is transported to the apparatus main body by the transport roll 17. After the half-moon roll 2 makes one rotation, the locking claw 13B of the toothless gear 13 is locked by the locking member 14A and stops at the fixed position shown in FIG.

Next, the operation and position fluctuation of the first actuator member 30 and the second actuator member 40 will be described with reference to FIGS. In the paper feeding device 60 of the present embodiment, as an example, in a cassette storing 500 sheets, when the number of sheets is 100 or less, the number of sheets is small, and when the number of sheets is more than 100, the amount of sheets is large.

FIGS. 3 and 4 show the state when a large amount of paper is used.
When the half-moon roll 2 is at the home position, as shown in FIG. 3, the first actuator member 30 has its sheet contact portion 30B
Is held by the upper surface of the sheet P, and the protrusion 30C is
The optical axis 16A of the photo sensor 16 is held by the projection 41 of the actuator member 40 of FIG.
Not blocked by. Therefore, in this case, the photo sensor 16
Is turned on.

On the other hand, when the meniscus roll 2 is rotated by the paper feed start signal and the paper feed is started, as shown in FIG.
4 tends to rotate in the direction of arrow B in FIG. 4 due to its own weight, but remains at the position in FIG.
A is not blocked by the light shielding unit 30A. Therefore, also in this case, the output signal of the photo sensor 16 is turned on.

FIGS. 5 and 6 show the state when the amount of paper is small.
Since the sheet stacking plate 20 is urged upward by the spring 51, the cassette body 1
1 rotates upward about an axis (not shown) provided in 1,
The position shown in FIGS. 5 and 6 is reached. A roller 21 is provided on the sheet stacking plate 20, and the roller 21 pushes up the second actuator member 40, and the holding of the protrusion 30 </ b> C by the protrusion 41 is released. When the half-moon roll 2 is at the home position, as shown in FIG. 5, the first actuator member 30 has its sheet contact portion 30B regulated by the upper surface of the sheet P, so that the optical axis 16A of the photo sensor 16 is shielded from light. It is not blocked by the part 30A. Therefore, in this case, the output signal of the photo sensor 16 is turned on.

On the other hand, when the half-moon roll 2 is rotated by the paper feed start signal and the paper feed is started, as shown in FIG. 6, the holding of the protruding portion 30C by the protruding portion 41 is released. The first actuator member 30 rotates in the direction of arrow B in FIG.
, The optical axis 16A of the photosensor 16 is blocked by the light shielding portion 30A. Therefore, in this case, the output signal of the photo sensor 16 is turned off.

FIG. 7 shows a state when the paper is exhausted. When the sheet runs out, the sheet contact portion 30B of the first actuator member 30 falls into the slit 20A (see FIG. 2) provided on the upper surface of the sheet stacking plate 20, and reaches the position shown in FIG. In this case, the optical axis 16A of the photosensor 16 is shielded by the light shielding unit 30A, and the output signal of the photosensor 16 is turned off.

With the mechanism described above, the output signal of the photosensor 16 changes as shown in Table 2 below depending on the presence or absence of a sheet and the amount of the sheet.

[0043]

[Table 2]

If the cassette is once pulled out to replenish the cassette with paper, and then remounted,
As shown in FIG. 3, it is necessary to reset the holding of the protrusion 30 </ b> C by the protrusion 41. Therefore, in this embodiment,
As shown in FIG. 8, a push-up cam portion 30D is provided on the first actuator member 30, and the cassette body 11 is
The configuration is such that the slope 11A of the cassette body 11 comes into contact with the push-up cam portion 30D during the pulling out in the direction. This contact causes the first actuator member 30 to move in the direction of arrow D.
The second actuator member 40 rotates in the direction of arrow E by its own weight. Thereby, the protruding portion 30C
Is returned to the state (FIG. 3) held by the protrusion 41.

In the above description, while the cassette main body 11 is being pulled out, the projecting portion 30C is returned to the state held by the projection 41 (the state shown in FIG. 3). The state shown in FIG. 3 may be restored.

As shown in FIG. 10, the paper feeder 60 is provided with a control unit 70 composed of a microcomputer or the like, and the control unit 70 has a magnetic disk device as a nonvolatile storage device. 72, a display 74, a keyboard 76, and a speaker 78 are connected. The control unit 70 includes the photo sensor 1
6 is connected, and the control unit 70 receives a light detection signal from the photo sensor 16. The control unit 70 is also connected to a control device (not shown) of the laser beam printer 50.

Next, as an operation of the present embodiment, a sheet state determination process executed by the control unit 70 in the sheet feeding device 60 having the above-described mechanism will be described with reference to FIGS. This paper state determination process is started when a power switch (not shown) of the laser beam printer 50 is turned on.

In step 102 of FIG. 11, the following initial setting processing is performed. First, information (hereinafter, referred to as sheet state information, for example, a sheet present state, a sheet absence state, a sheet large state, a sheet small state) stored in the magnetic disk device 72 regarding the previous sheet state is reset (cleared),
The photo sensor 16 is used as a sensor for detecting the presence / absence of paper (paper presence / absence sensor), and the detection result is read. Here, when there is a sheet, the sheet state information is set to the sheet present state, and the fact that the sheet is present is displayed on the display 74 to notify the operator. On the other hand, when there is no paper, the paper state information is set to the paper empty state, and the operator is notified by displaying on the display 74 that the paper is empty.

After the above-described initial setting process is completed, when an operator places a document and selects a tray (or automatically selects a tray according to the size of the document) and presses a print start button (not shown). A print command signal is sent from the control device (not shown) of the laser beam printer 50 to the control unit 70 for each page to be printed. When the control unit 70 receives the print command signal, the process proceeds to step 106, in which the photo sensor 16 is used as a sensor for detecting a small amount of paper (a small amount of paper detection sensor), and reading of the detection result is performed for 500 milliseconds. Not allowed.
Specifically, the permission / non-permission information of the detection of the small amount of paper for the selected tray is set to non-permission for 500 milliseconds.

In the next step 108, the counting process of the counter is executed until there is no paper in FIG. This process is a process of counting the number of sheets from when the amount of paper becomes small until there is no paper, and a counter that records the count value is referred to as a counter until there is no paper. Here, the counter is incremented until there is no sheet only when the sheet is set to a small amount at that time. As a result, the counter is counted by the number of times the print command signal is received in step 106 (that is, the number of printed sheets) in the state of the small amount of paper until there is no sheet. Note that the first time the sheet is not set in the small amount state, the process returns to the main routine of FIG. 11 without performing any processing.

In the next step 110, it is determined whether or not the paper is being fed (within 2 seconds after the print command is issued). If the paper is not being fed, the process proceeds to step 116, and the photo sensor 16 is set as the paper absence sensor. Use and read the detection result. Thereafter, the process proceeds to step 118 described later.

On the other hand, if paper is being fed in step 110,
In step 112, it is determined whether the photosensor 16 is used as a sensor for detecting a small amount of paper and reading of the detection result is permitted based on the permission / non-permission information of the detection of the small amount of paper at the time.

The permission / non-permission information for detecting a small amount of paper is set to non-permission in step 106,
After elapse of 500 milliseconds, the permission is set by the interrupt processing of FIG. Therefore, if 500 milliseconds have not elapsed after the setting of non-permission in step 106, the permission / non-permission information of the detection of a small amount of paper is set to non-permission, and the process proceeds to step 118 described later. on the other hand,
If 500 milliseconds have passed after the setting of non-permission in step 106, the permission / non-permission information of the detection of a small amount of paper is set to permission, so the process proceeds to step 114, where the photo sensor 16 detects the small amount of paper. Use as a sensor and read the detection result. Then, step 118
Proceed to.

In step 118, it is determined whether or not the detection result has changed when the photo sensor 16 is used as a paper presence / absence sensor. Go to 120 and FIG.
The sensor processing of the presence or absence of paper is performed. Here, when the state changes from the absence of paper to the presence, the paper status information is set to the presence of paper, and the fact that the presence of paper is present is displayed on the display 74 to notify the operator (step 16).
4). On the other hand, if there is a change from the presence of paper to the absence of paper, the paper status information is set to the absence of paper, and the display 74 is displayed on the display 74 to notify the operator (step 166). Further, the small amount of paper state is released (step 168), and the count value of the counter (the number of sheets from the small amount of paper until the paper is exhausted) is fetched until there is no paper at that time, and the fetched count value is stored in the magnetic disk drive. The information is stored in the memory 72 and displayed on the display 74 to notify the operator (step 170). The operator records the count value (the number of sheets from when the number of sheets becomes small until the sheet runs out). For example, the average value of the count values recorded several times and the original paper feeder 6 are recorded.
By comparing with the design value at 0, it is possible to check whether or not the boundary value in the determination of the amount of paper is kept in an appropriate range.

In the next step 122, the photo sensor 16
Is used as a sensor for detecting a small amount of paper, it is determined whether or not there is a change in the detection result. Only when there is a change in the detection result, the process proceeds to step 124, and the small amount of paper shown in FIG. Execute the detection sensor process. here,
If the amount of paper has changed from a large amount to a small amount, the paper state information is set to the small amount of paper, and the fact that the small amount of paper has been reached is displayed on the display 74 to notify the operator (step 184). On the other hand, if the amount of paper changes from a small amount to a large amount, the counter is initialized (count value is reset to "0") until there is no paper (step 186), and the small-paper state is released (that is, the paper state information is changed to the large-paper state). ), And the fact that the paper has become large is displayed on the display 74 to notify the operator (step 188).

Further, when the paper cassette is removed, there is a possibility that the paper has been replenished, so that the small amount of paper state is released (step 128 in FIG. 11). After that, the process returns to step 104 to detect a print command for the next page.

As is apparent from the above description, according to the present embodiment, one photo sensor 16 can detect both the presence or absence of a sheet and the amount of the sheet. That is, one photo sensor 16 can be used as a sensor for detecting a small amount of paper or a sensor for detecting whether or not there is a paper. This eliminates the need for separately installing a sensor for detecting the presence or absence of paper and a sensor for detecting the amount of paper as in the related art, and can reduce the cost of the apparatus.

Also, when the paper state changes from the presence of paper to the absence of paper or from a large amount of paper to a small amount of paper by the paper state determination process of FIG. Change is display 74
Is displayed, the operator can immediately recognize the change in the state of the sheet and can quickly take measures such as replenishing the sheet.

In the paper state determination processing of the above-described embodiment, the operator is notified of the change in the paper state by displaying the change on the display 74. Alternatively, a message indicating that the sheet state has changed may be recorded on the sheet and output.

When the paper cassette is removed as described above, not only is the small amount of paper released, but also if the power of the image forming apparatus 50 is turned off, the paper will not be available the next time the power is turned on. Since there is a possibility that the state has been changed to the replenished state, it is desirable to release the small amount of paper state.

[0061]

According to the present invention, it is possible to detect both the presence or absence of paper and the presence or absence of paper with a single sensor, thereby reducing the number of parts of the mechanism for detecting the presence or absence of paper and the presence or absence of paper. And the apparatus cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view illustrating a schematic configuration of an image forming apparatus according to an embodiment.

FIG. 2 is a schematic configuration diagram of a sheet feeding device.

FIG. 3 is a side view illustrating a non-sheet feeding state when a large number of sheets are fed in the sheet feeding device.

FIG. 4 is a side view illustrating a paper feeding state when a large amount of paper is supplied in the paper feeding device.

FIG. 5 is a side view illustrating a non-feed state when a small amount of paper is used in the paper feeding device.

FIG. 6 is a side view illustrating a paper feeding state when the amount of paper is small in the paper feeding device.

FIG. 7 is a side view illustrating a state in which there is no sheet in the sheet feeding device.

FIG. 8 is a side view illustrating a state in which the cassette is pulled out in the sheet feeding device.

FIG. 9 is a schematic view showing a rotation driving unit of a half-moon roll in the paper feeding device of FIG. 2;

FIG. 10 is a block diagram illustrating a configuration of a control system of the sheet feeding device.

FIG. 11 is a flowchart illustrating a control routine of a sheet state determination process according to the embodiment.

FIG. 12 is a flowchart showing a subroutine of a counting process of a counter until there is no paper.

FIG. 13 is a flowchart illustrating an interrupt processing routine that is interrupted 500 milliseconds after disabling the detection of a small amount of paper.

FIG. 14 is a flowchart illustrating a subroutine of sheet presence / absence sensor processing.

FIG. 15 is a flowchart showing a subroutine of a small-sheet detection sensor process.

[Explanation of symbols]

 2 Half Moon Roll 16 Photosensor (Sensor) 20 Paper Loading Plate 20A Slit 30 First Actuator Member 40 Second Actuator Member 50 Image Forming Device 60 Feeder 70 Controller 72 Magnetic Disk Device (Non-Volatile Memory) 74 Display 78 Speaker P paper

Claims (9)

[Claims] 1. A sheet feeding device for sequentially feeding sheets stacked on a sheet stacking plate to an image forming apparatus, wherein the number of sheets stacked on the sheet stacking plate is larger than a predetermined reference amount. And the presence or absence of the stacked sheets is detected by the same sensor. 2. The paper feeding device according to claim 1, wherein the sensor detects a small amount of paper during paper feeding and detects the presence or absence of paper during non-paper feeding. 3. A sheet feeding device for feeding sheets stacked on a sheet stacking plate urged in an upward direction sequentially to an image forming apparatus by repeatedly rotating a half-moon roll in one direction in units of one rotation. An optical sensor for detecting light passing through a predetermined optical path, and an optical path of the optical sensor in accordance with the vertical movement of the upper surface of the sheet against the urging force in cooperation with the rotation of the half-moon roll during paper feeding. A first actuator member that moves between a first position to block and a second position retracted from the optical path; and, when the amount of paper is larger than a predetermined reference amount, moves the first actuator member to the second position. A second actuator member that holds and releases the holding of the first actuator member when the paper amount is equal to or less than a predetermined reference amount. The first actuator member releases the holding. In the state Moving to the first position when there is no paper and when there is paper when feeding, and moving to the second position when there is paper when not feeding. apparatus. 4. The sheet feeding device according to claim 3, wherein the second actuator member is disposed so as to follow a position of the sheet stacking plate. 5. The apparatus according to claim 1, further comprising a paper cassette mounting portion, wherein when the paper cassette is detached from the mounting portion or when the paper cassette is mounted on the mounting portion, the first actuator member is connected to the second actuator member. The sheet feeder according to claim 3, wherein the sheet is reset to a state held by the actuator member. 6. A determining means for determining whether or not a sheet is larger than a predetermined reference amount and the presence or absence of a sheet based on a detection result of light by the optical sensor, and a notifying means for notifying the determination result. The paper feeding device according to claim 3, further comprising: 7. A paper cassette further comprising: a paper cassette mounting portion; and detecting means for detecting at least one of whether the paper cassette has been removed from the mounting portion and whether the power has been turned off. The paper feeder according to claim 6, wherein the information of the determination result is reset when it is detected that the power supply is removed or the power is turned off. 8. The paper feeding apparatus according to claim 1, further comprising a counting means for counting the number of sheets from when the number of sheets becomes equal to or less than a predetermined reference amount to when the sheets are exhausted. 9. A sheet feeding device having at least two sheet stacking units and sequentially feeding sheets from each sheet stacking unit to the image forming apparatus, wherein the sheets stacked in each sheet stacking unit are set to a predetermined standard. Paper amount detecting means for detecting whether the amount is larger than the amount, setting means for setting whether to enable or disable detection of a small amount of paper for each sheet stacking unit, and information set And a storage means for storing in a nonvolatile memory.