JP2001114452A - Sheet feeding device and sheet remaining amount detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet-feeding device capable of accurately grasping a sheet remaining amount. SOLUTION: A height of the paper loaded on a tray 401 is determined by subtracting a distance from a face position sensor 404 capable of detecting the arrival of the uppermost paper to a taking-out position by the paper feeding- out operation on the basis of the result of the measurement by a distance measuring sensor 401, to a non-detection condition (position 404b), from a result of the subtraction of a distance to the uppermost paper measured by a distance measuring sensor 201, from a distance between a lowermost position of the tray 401 stored in advance at the power source-on and an installation position of the distance measuring sensor 201, then a thickness of one sheet of paper is determined on the basis of the distance of the face position sensor 404 to the non-detection condition by the paper feeding operation, and the counted number at that time, to predict the paper remaining amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus for stacking sheets on a tray inside the apparatus and conveying the sheets to an image forming apparatus and the like, and a method for detecting the remaining amount of sheets.

[0002]

2. Description of the Related Art The operation of a conventional sheet feeding device (sheet feeding device) will be described with reference to FIGS. 8 and 9. FIG.

FIG. 8 is an electric block diagram showing a control structure of a conventional general paper feeder. In FIG. 8, reference numeral 801 denotes a CPU 801 for controlling all the paper feeders. Presence sensor 303, door sensor 30
4. Paper supply solenoid 305, paper size detection switch 30
6, jam sensor 307, tray home position sensor 308, tray elevating motor 309, transport motor 31
0 are respectively connected.

[0004] How these electric components are configured will be described with reference to FIG.

FIG. 9 is a cross-sectional view showing the configuration of a conventional general paper feeder. In FIG.
Reference numeral 01 denotes a tray. A paper presence sensor 803 is connected to the tray 401 so that it is possible to detect that the paper (sheet) has run out. The tray 401 can be lowered to the lowest position by a tray elevating motor 309 when the door sensor 304 detects the opening of the door. The confirmation that the tray 401 has been lowered to the lowermost position is made by a change in the state of the tray home position (HP) sensor 308.

[0006] By lowering the tray to the lowest position when the door is opened, the user can easily stack a stack of sheets.

When the door sensor 304 detects that the user has stacked the sheets and the door is closed, the upper surface of the sheets stacked on the tray 401 is moved to a position where the surface position sensor 302 for detecting the upper surface of the sheet is turned off. Is raised by the tray elevating motor 309 to be in a transportable state. Further, the size of the sheets stacked on the tray 401 can be selected by the user. Generally, a dial-type top is configured to press three switches.
1 can recognize the paper size.

In a state in which conveyance can be started, when there is a sheet feeding instruction from the image forming apparatus, the CPU 301 drives the sheet feeding solenoid 305 and transmits the rotation of the conveyance motor 310 to the sheet feeding roller 402. As the paper feed roller 402 rotates, the top sheet stacked on the tray 401 becomes the A shown in FIG.
, And fed into the image forming apparatus further downstream by the transport roller 403 located on the downstream side in the transport direction.

If a conveyance failure occurs during the conveyance of the sheet into the image forming apparatus after the start of sheet feeding, the state is detected by a jam sensor 307 located downstream of the sheet feeding roller 402, and the state is detected. The subsequent conveyance is stopped so that the sheet in which the conveyance failure has occurred does not become difficult for the user to remove.

The above-described paper feeding operation is repeated to
Even if the position of the upper surface of the paper stacked on the paper 1 is gradually lowered, the paper feed roller 402 is lowered by its own weight, and the paper can be fed to a certain paper feed position without any problem. Also, when the position of the upper surface of the paper stacked on the tray 401 gradually decreases and the surface position sensor 302 reaches the ON position 404b, the upper surface position of the paper stacked on the tray 401 is changed to the surface position sensor 302. 40 is the off position of
Until the tray 4a reaches the tray 4a.
Increase 01.

Further, as the number of sheets stacked in the sheet feeding device 400 gradually decreases and the tray rises, a plurality of sheet remaining amount sensors 405 (the sheet remaining amount sensor 311 in FIG. 8) exist.
), But changes state sequentially from the bottom. By displaying the changing state with an external LED or the like, the number of sheets remaining in the sheet feeding device 400 is roughly confirmed. Generally, using three LEDs, 0-25%,
26 to 50%, 51 to 75%, and 76 to 100% are displayed.

[0012]

However, in the above-mentioned conventional sheet feeding apparatus, there is no means for accurately confirming the number of sheets on the stacking tray, and it is impossible to judge when the sheet runs out. There was a problem.

For this reason, when the user tries to print a large number of jobs, the user cannot notice if the paper runs out during the printing, and even if he goes to the printer when the user thinks that the printing is completed, Actually, printing has not been completed, and there has been a problem that a waste of time has been caused in that the paper is added and the printing is waited again until the printing is completed.

Further, when the paper runs out during printing, there is a problem that the inconvenience of the user waiting for the next print is broken.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and provides a sheet feeding apparatus and a sheet remaining amount detecting method capable of accurately grasping the remaining amount of sheets. With the goal.

[0016]

A sheet feeding apparatus and a sheet remaining amount detecting method according to the present invention are configured as follows.

(1) In the sheet feeding apparatus, a tray on which sheets are stacked, elevating means for elevating and lowering the trays in accordance with the amount of stacked sheets, and an uppermost sheet on the tray moved by the elevating means are provided. Position detecting means for detecting that the sheet has reached a predetermined sheet take-out position, measuring means arranged above the sheets stacked on the tray, and measuring a distance from the arrangement position to the uppermost sheet; Counting means for counting the number of fed sheets, and the difference between the distance until the position detecting means changes to the non-detection state by the feeding of the sheet measured by the measuring means and the number of fed sheets at that time One of the sheets
The thickness per sheet is obtained, and the subtraction result of the distance from the specific position of the tray stored in advance at the time of power supply to the arrangement position of the measuring means and the distance to the uppermost sheet measured by the measuring means at that time. Further, the height of the sheets stacked on the tray, which is reduced by the feeding operation of the sheets within a predetermined period based on the measurement result by the measurement unit, is subtracted to obtain the height of the sheets stacked on the tray. The remaining amount of the sheets is predicted from the thickness per sheet and the height of the sheets stacked on the tray.

(2) In the sheet feeding apparatus, a tray on which sheets are stacked, elevating means for elevating and lowering the trays according to the amount of stacked sheets, and an uppermost sheet on the tray moved by the elevating means are provided. Position detecting means for detecting that a predetermined sheet take-out position has been reached, and measuring means arranged above the sheets stacked on the tray and measuring a distance from the arrangement position to the uppermost sheet. The thickness per sheet of the sheet is determined from the difference between the distances measured by the measuring unit before and after the feeding of the sheet, and the arrangement position of the measuring unit is determined from a specific position of the tray stored in advance at power-on. From the result of subtraction of the distance to the uppermost sheet and the distance to the uppermost sheet measured by the measuring means at that time, based on the result of measurement by the measuring means. The height of the sheets stacked on the tray is obtained by subtracting the height of the sheets stacked on the tray, which has been reduced by the sheet feeding operation during the period, to determine the thickness per sheet of the sheet and the tray. The remaining amount of the sheets is predicted from the height of the sheets stacked on the sheet.

(3) The sheet feeding apparatus according to the above (1) or (2), further comprising a non-volatile storage means for storing the height of the sheets stacked on the tray in the storage means. When the power is turned on again after the power is turned off, the sheets are stacked on the tray which is reduced by the sheet feeding operation within a predetermined period based on the measurement result by the measuring means from the height of the sheet stored in the storage means before the power is turned off. The height of the sheets stacked on the tray is obtained by subtracting the height of the sheet.

(4) In the sheet feeding apparatus according to any one of the above (1) to (3), the predetermined period is a period until the position detecting means repeatedly changes to a non-detecting state by sheet feeding.

(5) In any one of the sheet feeding devices (1) to (4), the specific position of the tray is the lowest position.

(6) In the sheet remaining amount detecting method, the tray on which the sheets are stacked is moved up and down by the elevating means according to the amount of the sheets loaded, and the uppermost sheet on the tray moved by the elevating means is a predetermined sheet. The arrival at the take-out position is detected by the position detection means, and the distance from the arrangement position of the measurement means to the uppermost sheet is measured by the measurement means arranged above the sheets stacked on the tray, The number of sheets fed by the sheet is counted by counting means, and the difference between the distance until the position detecting means changes to the non-detection state by the feeding of the sheet measured by the measuring means and the number of fed sheets at that time are used. The thickness per sheet is determined, and the distance from a specific position of the tray, which is stored in advance when power is turned on, to the arrangement position of the measuring means is determined. From the subtraction result of the distance to the uppermost sheet measured by the measuring means at that time, the sheet is further loaded on the tray reduced by the sheet feeding operation within a predetermined period based on the measurement result by the measuring means. The height of the sheets stacked on the tray is obtained by subtracting the height of the stacked sheets, and the remaining amount of the sheets is predicted from the thickness per sheet of the sheets and the height of the sheets stacked on the tray. I did it.

(7) In the sheet remaining amount detecting method, the tray on which the sheets are stacked is moved up and down by the elevating means according to the amount of the sheets loaded, and the uppermost sheet on the tray moved by the elevating means is a predetermined sheet. The arrival at the take-out position is detected by position detection means, and the distance from the arrangement position of the measurement means to the uppermost sheet is measured by the measurement means arranged above the sheets stacked on the tray. The thickness per sheet of the sheet is determined from the difference between the distances measured by the measuring unit before and after the feeding of the sheet, and the arrangement position of the measuring unit is determined from a specific position of the tray stored in advance at power-on. From the result of subtraction of the distance to the top sheet and the distance to the uppermost sheet measured by the measuring means at that time. The height of the sheets stacked on the tray is obtained by subtracting the height of the sheets stacked on the tray reduced by the sheet feeding operation within the predetermined period based on the thickness of the sheet. And the remaining amount of the sheets is predicted from the height of the sheets stacked on the tray.

(8) In the method for detecting the remaining amount of sheets according to the above (6) or (7), the height of the sheets stacked on the tray obtained in the nonvolatile storage means is stored, and the power is turned off. When the power is turned on again, before the power is turned off, the height of the sheets stacked on the tray, which is reduced by the sheet feeding operation within a predetermined period based on the measurement result by the measuring means from the sheet height stored in the storage means, is calculated. The height of the sheets stacked on the tray is obtained by subtraction.

(9) In any of (6) to (8) above, the predetermined period is a period until the position detecting means repeatedly changes to the non-detection state by feeding the sheet. .

(10) In any of (6) to (9) above, the specific position of the tray is the lowermost position, and the position of the measuring means is determined from the previously stored lowermost position. The height of the sheet was determined using the distance to the sheet.

[0027]

(Embodiment 1) FIG. 1 is an electric block diagram showing a control configuration of a sheet feeding apparatus (sheet feeding apparatus) according to Embodiment 1 of the present invention, and FIG. 2 is a sheet feeding apparatus according to Embodiment 1. FIG. 3 is a flowchart showing a control procedure for detecting the remaining amount of sheets (sheets) in the sheet feeding device according to the first embodiment of the present invention.

The first embodiment will be described below with reference to FIGS. 1, 2 and 3.

In FIG. 1, 301 is a CPU, 302 is a surface position sensor, 304 is a door sensor, 305 is a paper feed solenoid, 306 is a paper size detection switch, 307 is a jam sensor, 308 is a tray home position sensor,
09 is a tray elevating motor, 310 is a transport motor,
These are the same components as those in FIG. 8, and are denoted by the same reference numerals. The difference from FIG. 8 is that the distance measurement sensor 101 is added, and the paper presence sensor 303 and the remaining paper amount detection sensor 311 are deleted. Also, in FIG. 2, the same components as those of the conventional example are denoted by the same reference numerals.

A distance measuring sensor 101 (corresponding to the distance measuring sensor 201 in FIG. 2) as a measuring means added in FIG.
Is, as shown in FIG.
It is installed above the trailing end position of the paper stacked on the top 1 and the distance from that position to the upper surface of the paper can be read as an analog value. A hole is provided at a position where the distance measuring sensor 201 and the tray 401 face each other,
By preventing the light emitted from the distance measuring sensor 201 from being reflected, it is possible to have a function of detecting the presence / absence of the paper stacked on the tray 401.

For this reason, the total cost of the system is lower than that of the conventional system.

Next, a procedure for detecting the remaining amount of paper in the paper feeding device 400 in this embodiment will be described with reference to the flowchart of FIG. This operation is performed by a ROM (not shown).
Is executed in accordance with an instruction from the CPU 301 based on the program stored in the.

When the power is turned on, the distance from the distance measuring sensor 201 to the upper surface of the paper loaded on the tray 401 is measured in step S301, and the information is stored in a memory A (not shown) (step S302). ). afterwards,
In step S303, the tray motor (elevating means)
309 is driven to raise the tray 401 on which the sheets are stacked.

When the tray 401 is lifted, the surface position sensor (corresponding to the surface position sensor 404 in FIG. 4) 302, which is a position detecting means, is turned off in step S304, that is, when a predetermined sheet feed (feed position) is reached. Continue until you decide,
When it is determined that the surface position sensor 302 has been turned off (the position 404a in FIG. 4) (the determination in step S304 is Yes), the lifting of the tray 401 is stopped, and at that time the distance measuring sensor 201
From the paper to the top surface of the paper (step S30)
5). The measured information is stored in the memory B (not shown) (step S306), and the subtraction result of the information stored in the memory B and the information stored in the memory A is stored again in the memory A (step S307). Here, the information stored in the memory A is the amount of rise of the tray 402 when the power is turned on.

In step S308, when a paper feeding instruction is transmitted from the image forming apparatus (the determination in step S308 is Yes), in step S309, the paper feeding solenoid is driven to rotate the paper feeding roller 402 to feed paper. Only one top sheet loaded in the apparatus 400 is fed. Then, a sheet feeding counter (counting means) (not shown) for counting the number of fed sheets is counted up (step S310).

In step S311, the sheet is fed, and the surface position sensor 302 is turned on (position 404b in FIG. 4).
It is determined whether the detection has been performed, that is, whether or not the detection has been performed.
If the surface position sensor 302 is not on, step S3
The process transitions to 08 and waits until a paper feed instruction is received from the image forming apparatus. On the other hand, the number of sheets fed increases and the surface position sensor 3
02 is turned on (the determination in step S311 is Ye
s) The distance from the distance measuring sensor 201 to the upper surface of the sheet at that time is measured (step S312), and the information is stored in the memory C (not shown) (step S313).

When the processing of step S313 is completed, the tray 401 on which the sheets are loaded is raised until the surface position sensor 302 is turned off (steps S314 and S315), and when the surface position sensor 302 is turned off (step S315).
The determination of Yes is made). The lifting of the tray 401 is stopped, and a counter (not shown) for counting the number of times the tray 401 is raised other than when the power is turned on is counted up (step S316).

In step S317, step S313
In step S306, the distance information stored in the memory C when the surface position sensor 302 is turned on is subtracted from the distance information stored in the memory B in step S306 when the surface position sensor 302 is turned off. Here, the information stored in the memory C is a rising amount when the sheet feeding position which has been lowered by the plurality of sheet feeding processes is raised again.

Based on the above information, in step S318, the distance measuring sensor 201 previously stored in the storage unit (not shown) is used.
From the distance t to the tray 401, the distance at which the tray 401 was raised when the power was turned on (stored in the memory A) and the distance at which the tray 401 was raised stepwise (the result of multiplication of the information in the memory C and the counter y). The distance information per sheet is obtained from the number x of sheets fed to raise the tray 401 by one step, and the result is subtracted from the subtraction result to obtain the number m of sheets remaining in the sheet feeding device. Is calculated by calculation.

In step S319, the counter x, which is a counter for the number of sheets fed, is cleared, and the process proceeds to step S308 to repeat the above processing.

As described above, in this embodiment, the distance that the tray is raised when the power is turned on and the distance that the tray is raised stepwise are subtracted from the distance from the distance measuring sensor to the tray stored in the storage means in advance. The distance information per sheet is obtained from the number of sheets fed to raise the tray by one step, and the result is divided by the subtraction result to calculate the number of sheets remaining in the sheet feeding device by calculation. be able to.

Embodiment 2 In Embodiment 1, the tray 401
Each time the distance is raised by one step, distance information per sheet is calculated from the amount of rise of the tray at that time and the number of sheets fed, and this information is stored in advance in the distance from the distance measuring sensor 201 to the tray 401 stored in the storage means. From the tray 40 when the power is turned on.
A case has been described in which the number of sheets remaining in the sheet feeding device is predicted by dividing the calculation result obtained by subtracting the distance in which the tray 401 is raised stepwise from the distance in which the tray 1 is raised.

In the present embodiment, the amount of rise of the tray 401 to be raised in one step is averaged, and the number of sheets remaining in the paper feeding device 400 is more accurately predicted based on the averaged value. The case of controlling will be described. In addition,
The basic configuration of the device is the same as in FIGS.

FIG. 4 is a flowchart showing the control means for detecting the remaining amount of paper according to the second embodiment.
This embodiment will be described based on the flowchart of FIG.
This operation is executed in accordance with an instruction from the CPU 301 based on a program stored in a ROM (not shown).

Note that the same steps as those in the flowchart of FIG. 3 are denoted by the same reference numerals, and the description will be simplified.

In step S317, the distance information from when the surface position sensor 302 is turned on to when it is turned off is stored in the memory C. In step S401, the contents of the memory D (not shown) and the contents of the memory C are added, and the operation is performed. Store result in memory D
To be stored. Note that the contents of the memory D are initially set to 0, and the contents obtained by sequentially adding the amount of rise each time the tray 401 is raised by one step are stored. That is, the total value of the number of times the tray is raised is stored.

In step S402, step S401
Is divided by the number of times the tray 401 counted up in step S316 is raised, and the result is stored in the memory E (not shown). For this reason, the average value of the amount of rise of the tray is stored in the memory E.

In step S403, step S402
Using the average value of the rise amount obtained in (stored in the memory E),
The number of sheets remaining in the sheet feeding device 400 is calculated.

As described above, in this embodiment, the total value of the amount of rise of the tray that has risen a plurality of times is divided by the number of times of rise to obtain an average value, and the distance information per sheet is based on the information. Was calculated, and the total value of the distance in which the tray 401 was raised when the power was turned on and the distance in which the tray 401 was raised stepwise was subtracted from the distance from the distance measuring sensor 201 to the tray 401 previously stored in the storage means. By dividing by the result, the number of sheets remaining in the sheet feeding device 400 can be calculated by calculation.

(Third Embodiment) In the second embodiment, the information obtained by averaging the amount of rise of the tray 401 raised in one step, the number of times the tray 401 is raised in steps, and the one-step tray 401 are raised The calculation results of the number of sheets fed during the interval, the distance information from the distance measuring sensor 201 to the tray 401 stored in the storage means in advance, and the distance at which the tray 401 was raised when the power was turned on, are stored in the sheet feeding device 400. The case where control is performed so as to predict the number of remaining sheets has been described.

In this embodiment, the distance information of one sheet and the distance measurement sensor 201 stored in the storage means in advance from the tray 40
1, the number of sheets remaining in the sheet feeding device 400 is predicted from the total value of the distance information up to 1, the distance that the tray 401 was raised when the power was turned on, and the raised value of the tray that was raised stepwise. Will be described. In addition,
The basic configuration of the device is the same as in FIGS.

FIG. 5 is a flowchart showing control means for detecting the remaining amount of paper according to the third embodiment.
This embodiment will be described based on the flowchart of FIG. This operation is executed in accordance with an instruction from the CPU 301 based on a program stored in a ROM (not shown).

Note that the same reference numerals are given to portions performing the same processes as those in the flowcharts of FIGS. 3 and 4, and the processes are simplified.

In step S501, the position information of the upper surface of the sheet when the surface position sensor 302 stored in step S306 is turned off is further stored in a memory F (not shown), and in step S308, there is a sheet feeding instruction from the image forming apparatus. Wait until. If there is a paper feed instruction (the determination in step S308 is Ye
s) Only the top sheet of the stacked sheets is fed (step S309), and a counter for averaging the distance information per sheet is counted up (step S310).

In step S502, the distance to the upper surface of the stacked sheets after feeding is measured, and the result is stored in a memory G (not shown) (step S503).

In step S504, step S503
The distance information on the upper surface of the sheet before feeding stored in step S501 is subtracted from the distance information on the upper surface of the sheet after feeding stored in step S501, and stored in a memory H (not shown). The information stored at this time is distance information per sheet.

In step S505, step S504
In order to average the information per sheet stored in the memory H, the information of the memory 1 not shown is added, and the information is stored in the memory I. In the memory I, an initial value 0 is input, and the total value is stored each time the distance information per sheet is calculated. This sum is
If the distance information per sheet is divided by the calculated number, the averaged distance information per sheet can be obtained.

At step S311, step S309 is executed.
Judge whether the surface position sensor is turned on as a result of
If it is not turned on (the determination in step S311 is N
o), the process proceeds to a step S506, and the information stored in the memory G in the step S503 is stored in the memory F. This processing is performed in step S308 when paper is fed again.
This is because the information is replaced as information before feeding.

In step S507, the distance information per sheet obtained in this manner is obtained from the distance information from the distance measuring sensor 201 to the tray 401 (information in the memory t) stored in the storage means in advance. At this time, the distance information (information in the memory A) in which the tray is raised and the total distance information (information in the memory D) in which the tray 401 is raised stepwise are subtracted, and the calculation result and the distance information per sheet are calculated. By dividing, the number of sheets m remaining in the sheet feeding device 400
Is calculated.

As described above, in this embodiment, the distance information per sheet is obtained from the difference between the distances of the upper surface of the sheet before and after the sheet is fed, and the distance information from the distance measuring sensor 201 to the tray 401 stored in the storage means in advance. Is divided by the subtraction result of the distance information obtained by raising the tray 401 when the power is turned on and the total distance information obtained by gradually raising the tray when the power is turned on.
Can be calculated.

Fourth Embodiment In the first, second, and third embodiments, the case is described in which the amount of rise of the tray 401 is determined when the power is turned on, and control is performed so as to predict the number of sheets remaining in the sheet feeding device 400 based on the result. .

In this embodiment, every time the tray 401 is lifted, the amount of lift up to that point is stored in a non-volatile memory, and the position of the tray 401 is controlled quickly when the power is turned on next time. The case will be described. The basic configuration of the device is the same as in FIGS.

FIG. 6 is a flowchart showing a control procedure for detecting the remaining amount of paper according to the fourth embodiment.
This embodiment will be described based on the flowchart of FIG.
This operation is executed in accordance with an instruction from the CPU 301 based on a program stored in a ROM (not shown).

Note that the same reference numerals are given to portions where the same processing as in the flowchart of FIG. 3 is performed.

In step S601, it is determined whether or not the tray home position sensor 308 is at the lowest home position, and if the tray home position sensor 308 is at the home position (step S601).
The determination at 601 is Yes), and the process proceeds to step S301 to measure the distance from the distance measuring sensor 201 to the upper surface of the sheet, and stores the information in the memory A.

In step S303, the tray 401 starts to be lifted. In step S602, the distance to the upper surface of the sheet at that time is measured, and the information is stored in the memory C (step S603). In step S604, step S3
02 is subtracted from the distance information to the upper surface of the paper when the tray home position sensor 308 is at the home position stored in the home position at step S603, and the result is subtracted. Is stored in a non-volatile memory (not shown).

In step S304, it is determined whether or not the surface position sensor 302 has been turned off by raising the tray 401, and the processing from step S303 to step S304 is repeated until the surface position sensor 302 is turned off.

Even if the power is cut off at this point, the distance information of the tray 401 rising is stored in the non-volatile memory.
01 can be grasped.

On the other hand, when the position of the tray 401 is not at the home position when the power is turned on (No in step S601), the process proceeds to step S605 to indicate that the position of the tray 401 is not at the home position when the power is turned on. Set the flag 1. Then, step S606
, The information in the non-volatile memory is read into a memory Z (not shown).

In step S607, the surface position sensor 302
It is determined whether or not is turned on. If the sensor 302 is on (Yes in step S607), the tray 401 is raised because the top surface of the sheet has not reached the sheet feeding position in this state.

First, at step S608, the distance to the top surface of the sheet at that time is measured and stored in the memory A. Then, after the tray 401 is lifted, (Step S
610), the distance to the upper surface of the sheet is measured again (step S611), and stored in the memory D (step S61).
2). In step S613, the distance information stored in the memory A in step S608 is used as the memory D in step S612.
Is subtracted, and the information is stored in the memory D. Here, the information stored in the memory D is the amount of rise of the tray 401 after power-on.

In step S614, the information stored in the memory D in step S613 is subtracted from the information read from the nonvolatile memory, and the result is stored in the nonvolatile memory. In step S615, the tray 401 that has risen is
It is determined whether or not the sheet No. 03 has not reached the position where the tray 401 is turned off.
Are repeated until the surface position sensor 203 reaches the off position.

Even if the power is turned off during the processing from step S610 to step S615, the distance information on the upper surface of the sheet on the tray 401 immediately before the power is turned off is stored in the non-volatile memory. The position of the tray 401 can be grasped.

If the position of the upper surface of the sheet is between the off position and the on position of the surface position sensor 203 when the power is turned on (No in step S607), the process proceeds to step S616 to set a flag indicating that state. Set 2
In step S617, the counter indicating the number of times the tray 401 has been raised stepwise is decremented by one. This is because the position of the tray 401 was between the ON position and the OFF position of the surface position sensor 203 when the power was turned on, so that the number of times the tray 401 was raised from the ON position to the OFF position is counted up one time unless the counter value is subtracted. This is because

In step S618, the distance to the upper surface of the sheet at that time is measured, and the information is stored in the memory A in step S619.

If there is a feed instruction in step S308, only the top sheet of the stacked sheets is fed in step S309. Then, in step S310, a counter for counting the number of fed sheets is counted up.

In step S311, it is determined whether or not the upper surface of the sheet is lowered by the sheet feeding operation and the surface position sensor 203 is turned on. If the surface position sensor 203 is not turned on, the processing from step S308 to step S311 is repeated.

When the upper surface of the paper is lowered, the surface position sensor 2
03 is turned on (the determination in step S311 is Ye
s), the process proceeds to step S312 to measure the distance to the upper surface of the sheet at that time, and stores the result in the memory C. In step S314, the tray starts to be lifted, and the distance to the upper surface of the sheet is measured (step S62).
0), and stores the result in the memory B (step S62).
1).

In step S622, the information stored in memory B in step S621 is subtracted from the information stored in memory C in step S313, and the result is stored in memory B.

In step S623, the surface position sensor 20 stored in step S622 is stored based on the information in the nonvolatile memory.
The information in the memory B, which is the amount of increase increased from 3, and the information stored in the memory E described later are subtracted, and the result is stored in the nonvolatile memory.

In step S315, the surface position sensor 203
It is determined whether or not is turned off.
The processing from step 14 to step S315 is repeated. Even if the power is turned off during this process, the distance information of the tray 401 is stored in the non-volatile memory.
Even when the power is turned on, the position of the tray 401 can be grasped.

When the surface position sensor 203 is turned off (the determination in step S315 is Yes), the process proceeds to step S316, where a counter y for counting how many times the tray 401 is raised stepwise is counted up to reach the upper surface of the sheet. Is measured (step S624), and the result is stored in the memory B (step S625).

In step S626, the information stored in memory B in step S625 is subtracted from the information stored in memory C in step S313, and the result is stored in memory E. Here, the information stored in the memory E is the amount of rise in which the tray 401 rises after the surface position sensor 203 is turned on and then rises until the surface position sensor 207 is turned off.

In step S627, it is determined whether or not flag 1 indicating that tray 401 was at the home position when the power was turned on is cleared. If the flag 1 has been cleared, the process proceeds to the step S628, and the process proceeds to the step S6 from the information stored in the memory A in the step S302.
At 25, the information stored in the memory B is subtracted, and the result is stored in the memory F. The information stored here is the information when the tray 401 is at the home position when the power is turned on.
This is the amount by which the tray 401 is raised to a position where the upper surface of the sheet turns off the surface position sensor 203.

In step S629, based on the distance information t from the distance measuring sensor 201 to the tray 401 stored in the storage means in advance, distance information F indicating that the tray 401 has been raised when the power is turned on, and total information indicating that the tray 401 has been raised stepwise. By subtracting the distance and dividing the result by the distance information per sheet, the number m of sheets remaining in the sheet feeding device 400 is calculated.

On the other hand, if the tray 401 is not at the home position when the power is turned on (the determination in step S627 is N
o), the process proceeds to a step S630, and it is determined whether or not the flag 2 indicating whether or not the upper surface of the sheet is between the ON position and the OFF position of the surface position sensor 203 is cleared.

If the flag has been cleared (step S
630 is Yes), the process proceeds to step S631,
The amount of rise of the tray 401 stored in step S613 and the total amount of rise of the tray 401 gradually increased are subtracted from the information of the nonvolatile memory read in step S606,
The result is divided by the distance information per sheet to calculate the number of sheets remaining in the sheet feeding device.

On the other hand, if the position of the upper surface of the sheet when the power is turned on is between the ON position and the OFF position of the surface position sensor 203 (No in step S630), step S63.
The information stored in the memory A in step S619 is subtracted from the information stored in the memory B in step S625, and the result is stored in the memory D in step S625.

As described above, in the present embodiment, each time the tray 401 is lifted, the amount of lift up to that point is stored in the non-volatile memory so that the position of the tray can be quickly grasped when the power is turned on next. Can control.

(Embodiment 5) Embodiments 1 to 4 have described the prediction control of the number of sheets remaining in the sheet feeding device during normal sheet conveyance.

In the present embodiment, a case will be described in which control is performed so that the remaining amount of paper can be predicted, taking into account control during abnormal conveyance such as a jam. The basic configuration of the device is the same as in FIGS.

FIG. 7 is a flowchart showing control means for detecting the remaining amount of paper according to the fifth embodiment.
This embodiment will be described based on the flowchart of FIG.
This operation is executed in accordance with an instruction from the CPU 301 based on a program stored in a ROM (not shown).

In FIG. 7, the same processes as those in the third embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In step S308, when there is a feed instruction from the image forming apparatus, the flow shifts to step S309 to feed the top sheet stacked on the tray 401.

When a jam or a double feed is detected in step S701 (the determination in step S701 is Yes)
In order to prevent an erroneous measurement when the fed paper remains at the measurement position without being transported due to a jam or an erroneous measurement when the paper is excessively fed due to double feeding, steps S310 to S505 are performed. Skip the processing of
Control is performed so as not to refer to the measurement information of the paper fed at that time.

As described above, in the present embodiment, if a jam or a double feed occurs after the sheet is fed, the control is performed so as not to refer to the measurement information at that time, so that the sheet feeding device can be more accurately controlled. Can be predicted.

As described above, in the first to fifth embodiments, the sensor for detecting the surface position of the stacked sheets is turned on from the OFF position.
Always monitor the number of sheets fed before shifting to the position,
The distance in the stacking direction per sheet is obtained from the distance from the OFF position to the ON position of the surface position sensor and the number of sheets fed during that time.
F, the number of times the stacking tray has been raised, the distance that the paper on the stacking tray has been raised when the power is turned on, and the height of the stacked paper obtained at the position of the tray when the power is turned on is divided by the remaining paper. The amount can be predicted.

[0098]

As described above, according to the present invention,
The remaining amount of sheets can be accurately grasped, and it is possible to determine when the sheets are going to run out, so that there is an effect that the user waiting for printing is not inconvenienced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a control configuration of a sheet feeding apparatus according to a first exemplary embodiment.

FIG. 2 is a cross-sectional view illustrating a configuration of the sheet feeding device according to the first exemplary embodiment.

FIG. 3 is a flowchart illustrating a control procedure for detecting a remaining amount of paper according to the first embodiment.

FIG. 4 is a flowchart illustrating a control procedure for detecting the remaining amount of paper according to the second embodiment.

FIG. 5 is a flowchart illustrating a control procedure for detecting a remaining amount of paper according to a third embodiment.

FIG. 6 is a flowchart illustrating a control procedure for detecting a remaining amount of paper according to a fourth embodiment.

FIG. 7 is a flowchart illustrating a control procedure for detecting a remaining amount of paper according to a fifth embodiment.

FIG. 8 is a block diagram illustrating a control configuration of a conventional sheet feeding device.

FIG. 9 is a cross-sectional view showing the configuration of a conventional sheet feeding device.

[Explanation of symbols]

 101 Distance measuring sensor (measuring means) 201 Distance measuring sensor (measuring means) 302 Surface position sensor (position detecting means) 304 Door sensor 305 Paper feed solenoid 306 Paper feed size detection switch 307 Jam sensor 308 Tray home position sensor 309 Tray elevating motor ( Elevating means) 310 transport motor 401 tray 402 paper feed roller 403 transport roller

Claims (10)

[Claims] A tray on which sheets are stacked, elevating means for elevating and lowering the trays in accordance with an amount of the stacked sheets, and a top sheet on the tray moved by the elevating means reaches a predetermined sheet take-out position. Position detecting means for detecting that the sheet has been loaded, measuring means for measuring the distance from the position where the sheet is stacked on the tray to the uppermost sheet, and counting the number of fed sheets. Counting means, and the difference between the distance until the position detecting means changes to the non-detection state by the feeding of the sheet measured by the measuring means and the number of sheets fed at that time, and the number of sheets per sheet Determine the thickness, the distance measured from the specific position of the tray stored in advance at the time of power supply to the arrangement position of the measuring means and the measuring means at that time The height of the sheets stacked on the tray, which has been reduced by the sheet feeding operation within a predetermined period based on the measurement result by the measuring means, is further subtracted from the subtraction result with the distance to the uppermost sheet to obtain the tray. A sheet feeding device for obtaining the height of the sheets stacked on the tray, and estimating the remaining amount of the sheets from the thickness per sheet and the height of the sheets stacked on the tray. 2. A tray on which sheets are stacked, elevating means for elevating and lowering the trays according to the amount of the sheets stacked, and the uppermost sheet on the tray moved by the elevating means reaches a predetermined sheet take-out position. Position detecting means for detecting that the sheet is loaded on the tray, and measuring means for measuring a distance from the position where the sheet is stacked to the uppermost sheet. The thickness per sheet of the sheet is obtained from the difference between the distances measured by the measuring unit before and after feeding, and the distance from the specific position of the tray stored in advance when the power is turned on to the arrangement position of the measuring unit and the current time The sheet feeding operation within a predetermined period based on the result of the subtraction with the distance to the uppermost sheet measured by the measuring means, based on the result of the measurement by the measuring means. The height of the sheets stacked on the tray is obtained by subtracting the height of the sheets stacked on the tray, and the height of the sheets stacked on the tray and the height of the sheets stacked on the tray are obtained. A sheet feeding device for estimating a remaining amount of the sheet. 3. A non-volatile storage means, wherein the storage means stores the height of the sheets stacked on the tray, and
When the power is turned on again after the power is turned off, the sheet is loaded on the tray which is reduced by the sheet feeding operation within a predetermined period based on the measurement result by the measuring means from the sheet height stored in the storage means before the power is turned off. The sheet feeding device according to claim 1, wherein the height of the sheets stacked on the tray is obtained by subtracting the height of the set sheets. 4. The sheet feeding apparatus according to claim 1, wherein the predetermined period is a period until the position detecting unit changes to a non-detection state repeatedly by feeding the sheet. 5. The sheet feeding apparatus according to claim 1, wherein the specific position of the tray is a lowermost position. 6. A tray on which sheets are stacked is moved up and down by elevating means according to the stacking amount of the sheets, and a position is determined when the uppermost sheet on the tray moved by the elevating means reaches a predetermined sheet take-out position. The distance detected from the position where the measuring means is arranged to the uppermost sheet is measured by the measuring means arranged above the sheets stacked on the tray, and the number of sheets fed is counted. The thickness per sheet is calculated from the difference between the distance until the position detecting means changes to the non-detection state by the feeding of the sheet measured by the measuring means and the number of sheets fed at that time. And the distance from the specific position of the tray, which is stored in advance when the power is turned on, to the arrangement position of the measuring means, and the distance measured by the measuring means at that time. The height of the sheets stacked on the tray, which has been reduced by the sheet feeding operation within a predetermined period based on the measurement result by the measuring means, is further subtracted from the subtraction result with the determined distance to the uppermost sheet. Determining the height of the sheets stacked on the tray, and predicting the remaining amount of the sheets from the thickness per sheet and the height of the sheets stacked on the tray. Detection method. 7. A tray on which sheets are stacked is moved up and down by elevating means according to the amount of sheets loaded, and a position is determined when the uppermost sheet on the tray moved by the elevating means reaches a predetermined sheet take-out position. The distance from the arrangement position of the measurement means to the uppermost sheet is measured by the measurement means which is detected by the detection means and is disposed above the sheets stacked on the tray, and the sheet is fed. The thickness per sheet of the sheet is determined from the difference between the distances measured by the measuring unit before and after, and the distance from the specific position of the tray, which is stored in advance at the time of power-on, to the arrangement position of the measuring unit, and From the result of subtraction from the distance to the uppermost sheet measured by the measuring unit, the sheet of the sheet within a predetermined period based on the measurement result by the measuring unit is further obtained. The height of the sheets stacked on the tray is obtained by subtracting the height of the sheets stacked on the tray, which has been reduced by the feeding operation, to determine the thickness per sheet and the thickness of the sheets stacked on the tray. A sheet remaining amount detecting method, wherein a remaining amount of the sheet is predicted from a height. 8. The non-volatile storage means stores the height of the sheets stacked on the tray, and when the power is turned on again after the power is turned off, the height of the sheet stored in the storage means before the power is turned off. Subtracting the height of the sheets stacked on the tray, which is reduced by the sheet feeding operation within a predetermined period based on the measurement result by the measuring means, to obtain the height of the sheets stacked on the tray. The method according to claim 6 or 7, wherein the remaining sheet amount is detected. 9. The sheet remaining amount detecting method according to claim 6, wherein the predetermined period is a period until the position detecting means changes to a non-detecting state repeatedly by feeding the sheet. . 10. A specific position of the tray is a lowermost position, and the height of the sheet is obtained by using a previously stored distance from the lowermost position to an arrangement position of the measuring means. 10. The remaining sheet amount detection method according to any one of 6 to 9.