JPH04106027A - Paper feeding device - Google Patents

Abstract

PURPOSE:To prevent generation of jam and dog-ear of the paper in a device by outputting various alarm and a command for prohibiting the operation for display when a difference of a height of the top paper of the papers, which are piled on a tray, at a part near an end thereof and a height of the paper distanced from there exceeds a predetermined quantity. CONSTITUTION:At the time of elevating a tray 42, multiple detectors 25, 26 detect a height of the top paper P of the papers, which are piled on the tray 42, at near an end thereof and a position distanced from there respectively, and quantity of curl and wrinkle of the top paper P is judged with a difference of positions of the paper surface Pa where the detecting signal of the detectors 25, 26 is changed, and when that value exceeds a predetermined quantity, danger of generating jam or dog-ear or the like is judged, and various alarm and a command for prohibiting the operation is output to display it. Consequently, since the paper having a danger of generating jam can be eliminated easily at a stage before paper feeding stage in a paper feeding part, generation of jam or the like can be prevented previously.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a paper feeding device of a type in which a tray moves up and down, used in image forming apparatuses such as copying machines and printers.

[Conventional technology]

Conventionally, for example, in a copying machine, if the paper fed by the paper feeding device is curled or wrinkled, it is necessary to prevent it from folding or jamming on the conveyance path. Therefore, some devices are equipped with a detection device that measures the amount of paper curl on the conveyance path, and when the measured value exceeds a predetermined value, a danger warning display is displayed in a part that can be seen from the outside. Publication No. 63-287863).

[Problem to be solved by the invention]

However, when a detection device for measuring the amount of paper curl is installed on the conveyance path, the conveyance path is usually located in a relatively deep part of the device body. Even if the detection device detects heavily curled paper and issues a warning display, the operability when taking out the paper tends to be poor.

This invention was made in view of the above problems,
By detecting paper with large curls or wrinkles that can lead to ear scratches or jams, and issuing warnings, etc.
It is an object of the present invention to prevent the occurrence of paper jams, etc., and to enable curled paper to be taken out with good operability.

Another purpose is to be able to detect curls and wrinkles with high accuracy.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a tray for loading paper, a means for raising and lowering the tray, and a position corresponding to the vicinity of the edge of the upper surface of the paper on the tray and a position distanced therefrom, respectively. A plurality of detectors are arranged and each can detect the height of the paper surface by detecting the topmost paper surface on the tray, and paper surface detection signals from the plurality of detectors are sent when the tray is raised and lowered. A means is provided for determining the amount of curl or wrinkles on the topmost paper on the tray based on the difference in the changing position, and outputting various warnings and commands to prohibit operations when the difference exceeds a predetermined amount. This is a configuration of a paper feeding device.

In addition, the paper feeding device has the plurality of detectors detect the bottom surface of the tray when the tray is raised and lowered, and the variation in the detection position of each detector is corrected by the difference in the position where each detection signal changes. It is more effective to provide a means to do so.

[For production]

According to the image forming apparatus configured in this way, when the tray is raised and lowered, multiple detectors detect the height of the uppermost sheet of paper stacked on the tray near the edge and at a distance from there. The amount of curl or wrinkles on the topmost sheet of paper is determined based on the difference in the position at which the detection signal on the paper surface changes by the detector, and if this exceeds a predetermined amount, there is a risk of jamming or folding of edges. In some cases, various warnings and commands prohibiting operations are issued and displayed, so
Since the paper that is at risk of jamming can be easily removed in the paper feeding section before paper feeding, it is possible to prevent the occurrence of jams and the like.

Furthermore, if a means for correcting variations in detection positions of a plurality of detectors is provided, variations in individual detectors can be corrected, so curls and wrinkles on paper can be detected with higher accuracy.

〔Example〕

Embodiments of the present invention will be specifically described below with reference to the drawings.

Fig. 1 is a schematic diagram showing a plurality of detectors capable of detecting the height of the uppermost paper surface stacked on a tray, which is the main part of this invention, and the vicinity thereof, and Fig. 2 also shows the detectors. An overall configuration diagram showing an example of a copying machine equipped with a large-volume paper feeder,
FIG. 3 is a plan view showing the arrangement of the plurality of detectors shown in FIG. 1 on a plane.

As shown in FIG. 2, this copying machine 1 has an automatic document feeder 7 mounted on the top of the main body 2, and inside the main body 2,
Each section is provided with an optical system 31, an image forming section 4, a paper feeding section 5, a paper discharging section 6, and the like.

A charging section 16, a cleaning section 17, a transfer separation section 18, a developing section 19, and other sections are arranged around the photosensitive drum 15 of the image forming section 4, respectively.

The paper feed section 5 includes two paper feed cassettes 2OA and 20B each capable of storing a walking amount of paper P, a mass paper feed device 110 capable of storing a large amount of paper P at once, and a main body of the device above the paper feed unit 5. A paper feed cassette 20C that can be freely inserted into and removed from the paper feed cassette 20C is provided for each of the paper feed cassettes 2 and 2.

Corresponding to the mass paper feed device 10, a calling roller 31, a paper feed roller 32, and a reversing roller 33 are rotatably provided near the paper delivery port of the mass paper feed device [10].

Further, a fixing section 22 is provided between the image forming section 4 and the paper ejection section 6, and the toner image transferred onto the paper is heated and fixed by the fixing section 22, and the paper P is transferred to the paper ejection section 6. Sorter 2
Paper is ejected according to the mode specified on bin 3.

Large amount of paper feed! 1o is equipped with a tray 42 for stacking sheets P in the storage frame 24, and an elevating device (to be described later) that serves as a means for lifting and lowering the tray 42. The paper is raised to the uppermost paper feeding position and fed to the image forming section 4.

Then, when replenishing the paper P onto the tray 42,
Open the door 11 provided on the right side in FIG.

Also, this mass paper feeder! As shown in FIGS. 1 and 3, 10 is near one end of the upper surface of the uppermost sheet on the tray 42, and a position that approaches the calling roller 31 at a distance from the center in the width direction of the sheet. The uppermost paper surface Pa stacked on the tray 42
Two sensors 25 and 26 are provided, each of which can detect the height of the paper surface by detecting the height of the paper surface.

The sensor 25 is, for example, a reflective photosensor as shown in FIG. 4, and the light receiving element 25b receives the reflected light of the light irradiated from the light emitting element 25a onto the paper surface Pa, and the sensor 25 receives the reflected light from the light emitting element 25a onto the paper surface Pa. It is turned on and off, and in this embodiment, as shown in the characteristic diagram in FIG. Use one with the following characteristics.

Similarly, the sensor 26 also uses a reflective photosensor having the characteristics shown in FIG.

FIG. 6 is a perspective view showing an elevating device for elevating and lowering the tray of the mass paper feeder 10 and its related parts.

The lifting device 40 that lifts and lowers the tray 42 uses the driving force of a motor 43 to lift and lower the tray 42. The motor 43 rotates a belt 34 stretched between pulleys to drive a worm 35a and engage it. A drive shaft 36 that rotates the worm wheel 35b and is integrated with it.
Rotate.

Drive pulleys 39 and 39 are fixed to the drive shaft 36 on the outside of the front and rear side plates 37 and 38, respectively, and the drive wire 12 is partially wound around the drive pulleys 39 and 39 and stretched between the plurality of pulleys 28. 13 is rotated in the direction indicated by arrow A in FIG. 6 and in the direction opposite thereto by rotation of the drive shaft 36 in both forward and reverse directions.

A supporting member having a U-shaped cross section is fixed to the parallel vertical portion of each drive wire 12, 13 through the front and rear side plates 37, 38, respectively, and is fixed to the outside. Both ends of the 44.degree. 45 angle are fixed so that the tray 42 moves up and down when the drive wires 12 and 13 rotate.

Further, a disk 46 having slits formed at regular intervals along the outer circumferential direction is fixed to the rotating shaft of the motor 43, and a pulse generator 47 is provided corresponding to the slits of the disk 46, so that the motor 43 rotates. When the tray 42 moves up and down, a pulse is generated therefrom, and the number of pulses corresponds to the up and down movement of the tray 42.

Furthermore, inside the storage frame 24 of this mass paper feeder 10,
As shown in FIG. 7, there are five sensors 71 for detecting the remaining amount of paper.
A to 71E and a lower limit detection sensor 62 (both transmission type photosensors) for detecting the lower limit position of the tray 42 are provided, and these are arranged at intervals along the vertical direction of the tray 42. .

Each of the sensors 71A' to 71E has a positional relationship in which the detection portion is shielded from light by a light shielding plate 63 fixed to the side edge of the tray 42, and the length of the light shielding plate 63 in the vertical direction is increased. As a result, when the tray 42 moves within the range where the five sensors 61A to 61E and the lower limit detection sensor 62 are provided, any of the sensors (or two at the same time depending on the position of the tray) be)
The detection section is always shielded from light by the light shielding plate 63.

When each of the sensors 71A to 71E detects the tray 42 through the light-shielding plate 63, a sensor is provided on the operation panel of the main body 2 of the copying machine (see FIG. 2) corresponding to each sensor. The LEDs of each display section are illuminated so that the remaining amount of paper P on the tray 42 can be seen even from the outside.

In addition, in this large-volume paper feeder 10, when the tray 42 is raised and the top surface of the uppermost sheet of the stack of sheets stacked on the upper part reaches the upper limit paper feeding position, the uppermost sheet is moved to the calling roller 31 ( 2) and lift it up a little, the position of the member that was blocking the upper limit detection sensor (for example, a photo sensor, not shown) lowers and releases the light shielding, so the upper limit detection sensor turns on. In this state, the raising of the tray 42 is stopped.

Then, when paper feeding is started and the number of papers P on the tray 42 decreases, the position of the calling roller 31 is lowered, so that the upper limit detection sensor is shielded from light again, which causes the motor 43 to rotate again to the upward side of the tray. starts, and when the upper limit detection sensor is shielded from light again, its rise is stopped.

Further, although not shown in the figure, the mass paper feeder 10 is provided with a paper end sensor that detects whether or not there is paper P on the tray 42. The paper is pushed up against the bottom edge of the freely swingable filler.

The light shielding member integrated with the filler is in a position that does not shield the sensor's detection part from light, and when the paper runs out, the filler falls into the notch hole formed in the tray and swings, thereby blocking the light shielding member. The paper end is detected by shielding the detection part of the sensor from light.

When this paper end is detected, tray 4
2 automatically moves to the lower limit in preparation for paper replenishment.

Further, as shown in FIG. 2, on the upper surface of the storage frame 24,
A tray lowering switch 64 and a door display 65 are provided, and the tray lowering switch 64 is pressed to lower the tray 42 when replenishing paper. ) and blinks, and turns on when the tray 42 is lowered to its lower limit.

The door display 65 lights up when the door 11 is opened and goes off when it is closed.

By the way, as shown in FIG. 1, this large-volume paper feeding device 10 uses sensors 25 and 26 that can detect the height of the uppermost sheet P stacked on the tray 42 when the tray 42 is raised. The amount of curl or wrinkles on the top paper P is determined based on the difference in the position at which the detection signal changes (from OFF to ON in this example), and when the difference exceeds a predetermined amount, various warnings and actions are prohibited. The command to do so is automatically output.

All commands to issue the warning or prohibit the operation are issued by the tray control section 7o shown in FIG. That is, in this embodiment, the tray control unit 70 determines the amount of curls and wrinkles on the top sheet of paper, and when the amount exceeds a predetermined amount, outputs various warnings and commands to prohibit operations. Function.

The tray control section 70 is connected to a copying machine control section 80 and exchanges signals therebetween, and both the tray control section 7o and the copying machine control section 80 are central processing units having various judgment and processing functions. (CPU) and R, which is a program memory that stores various programs and fixed data.
OM and RA, which is a data memory that stores processing data.
M and an input/output circuit (Ilo) are each microcomputers, and the tray control section 70 is also equipped with a timer.

The tray control section 70 is a control section that controls each section of the mass paper feeder 10, and serves as a slave control section for controlling the copying machine so that the amount of curl of the uppermost sheet on the tray 42 is a predetermined amount. When the limit is exceeded, various warnings and prohibition commands are issued, and the raising and lowering of the tray 42 is controlled.

That is, the sensor 25 for detecting the amount of curl of the paper
, 26, a pulse signal from the pulse generator 47, and an upper limit detection sensor 66 from the tray 4.
The upper limit detection signal outputted when the paper on the tray 2 reaches the paper feeding position is inputted from the paper end sensor 67, and the paper out signal outputted when all the paper on the tray runs out is inputted from the paper end sensor 67, respectively.

Further, the lower limit detection sensor 62 outputs a signal when the tray 42 reaches the lower limit, the door sensor 68 outputs a signal when the door 11 (FIG. 2) is opened, and the size sensor A signal outputted according to the paper size is inputted from the tray lowering switch 69, and a signal outputted when the tray lowering switch 64 is pressed is inputted.

Then, signals are outputted to drive the motor 43 that raises and lowers the tray 42, and display signals for lighting up LEDs and the like are outputted to various display sections.

Further, the copying machine control section 8o performs various copy controls and peripheral device control as a master control section of each block.

That is, the operating section 5 provided outside the device main body 2
1. An optical system 3, an image forming section 4, a paper feeding section 5, a paper ejection section 6, a fixing section 22, which are provided inside the apparatus main body 2, respectively.
In addition to inputting various signals from the and other sensors, various drive signals are outputted to the drive systems of each part to drive them, and peripheral devices such as the automatic document feeder 7 and the sorter 23 are inputted. It also sends and receives signals to and from.

FIG. 9 is a flowchart showing the detection timing for determining the amount of curls and wrinkles on the paper, and the tray control unit 70 repeatedly executes determination of the amount of curls and wrinkles on the paper at predetermined timings based on this flowchart. .

First, in step 1, determine whether the power is on or not. If it is not on, proceed to step 2.
It is determined whether the time has elapsed or not, and if the time has not elapsed, the process proceeds to step 3, where it is determined whether or not the tray 42 has been replenished with paper P and the tray 42 is being raised.

If the result is NO, the process returns to the main routine; if the result is YES, the process proceeds to step 4, where it is determined whether the amount of curls and wrinkles exceeds a predetermined amount, which will be described later in FIG. 10. When the detection routine is completed, the process returns to the main routine.

In addition, when the power is turned on in the judgment in step 1 (determination of YES) and when 2 hours have elapsed in the judgment in step 2 (determination of YES), both step 5
The process proceeds to step 4, where the tray 42 is once lowered, and then the motor 43 is reversely rotated to raise the tray 42, and then the process proceeds to step 4, where the aforementioned detection routine is executed.

That is, in this embodiment, the following three cases are used as detection timings for determining the amount of curl or wrinkles on the paper.

(1) When the device is started up when the power is turned on (2) Once every two hours during the period (3) When the tray is raised after replenishing paper Figure 10 shows cases where the amount of curls and wrinkles exceeds the specified amount. FIG. 3 is a flowchart showing a detection routine for determining whether or not.

The tray control unit 70 repeatedly executes judgment and processing according to the flowchart in FIG. 10 at each predetermined detection timing shown in FIG. 9.

First, in step 11, when the tray is raised, the motor 43 rotates and starts counting pulses output from the pulse generator 47 corresponding to the amount of movement of the tray 42.

Next, in step 12, it is determined whether the sensor 26 on the side closer to the center of the paper shown in FIG.
If it is on, proceed to step 13 and memorize the number of pulses Ct when the sensor 26 is turned on (for example, the number of pulses from the lower limit at which the lower limit detection sensor 62 in FIG. 57 is turned on). Proceed to step 14, and if it is not turned on, proceed directly to step 14.

Therefore, this time, it is determined whether the sensor 25 located near the edge of the paper is turned on or not. If it is turned on, the process advances to step 15, and when the sensor 25 is turned on. The number of pulses C, (the number of pulses from the lower limit like C) is memorized and the process proceeds to step 16. If it is not turned on, the process directly proceeds to step 16.

In step 16, the upper limit detection sensor 66 (FIG. 8)
Determine whether or not it is turned on.

If it is not on, return to the main routine,
If it is on, proceed to step 17, then step 1
3 and the number of pulses C1 stored in step 15, respectively.
Call C, calculate the difference ΔC between cl and c2, and find its absolute value.

In this case, if 8C is a large value, the amount of curls or wrinkles will also be proportionally large.

Next, in step 18, the number of pulses ΔC obtained in step 17 is less than 50 pulses, that is, the amount of curls and wrinkles is 0.
It is determined whether the amount is approximately 5 mm and does not affect the copying operation, and if so, an instruction to permit copying is issued in step 19, and if not, the process proceeds to step 20 and the number of pulses is determined. ΔC is 50 or more and less than 150 pulses,
In other words, it is determined whether the amount of curls or wrinkles is about 5 to 15 mm, which puts a slight burden on the conveyance system but does not affect the copying operation, and if so, a warning is displayed in step 21. A command is issued to permit copying, and if not, the process proceeds to step 22.

Then, in step 22, it is determined whether the number of pulses ΔC obtained in step 17 is 150 pulses or more, that is, the amount of curls and wrinkles is 15 mm or more, which is an amount that is likely to cause jams, folded edges, etc. If so, a command is issued in step 23 to prohibit all copying, and a warning display is issued to replace the paper with one that is free from curls and wrinkles, and the process proceeds to step 24.

Further, in step 22, if the number of pulses ΔC is not 150 pulses or more, the process directly proceeds to step 24, where the pulse count is stopped and reset, and then the process returns to the main routine.

FIG. 11 is a schematic diagram similar to FIG. 1 showing another embodiment of the present invention, and parts corresponding to those in FIG. 1 are given the same reference numerals.

This embodiment differs from the previous embodiment in that the two sensors 25 and 26 placed at the same positions as in FIG. The only difference is that a means for correcting the variation in the detection position of each sensor due to the difference is also provided.

A tray control section 70' (tray control section 70') similar to the tray control section 70 in the above embodiment described in FIG. 8 functions as a means for correcting the variation.
Since the related configuration is the same as 0, detailed explanation will be omitted)
The tray control unit 70' executes judgment and processing at a predetermined timing according to a flowchart described later.

By the way, the sensor 25 normally used in this embodiment,
In a reflective photosensor like 26.

The distance at which an object can be detected by shining light on it depends on the set detection distance (focal length), as shown in Figure 12, and varies from 8 to 20 mm depending on the individual element (with hatching). range).

Therefore, in devices that require high detection accuracy, this variation becomes a problem, so the detection distance is adjusted to reduce the variation, such as by using a sensor with an adjustment volume that allows sensitivity adjustment.

However, such a sensor with an adjustment volume is not only expensive in terms of cost, but also requires a lot of effort to adjust the sensitivity of the sensor for each device, which can be troublesome.

According to this embodiment, no adjustment with individual variations,
Sensors 25 and 26 which are wireless reflective photosensors
is used as is, and its individual variations are automatically measured and corrected, so curls and wrinkles on the top sheet P on the tray 42 can be detected with high detection accuracy.

FIG. 13 shows the sensor 25, which is executed by the tray controller 70'.
26 is a flowchart showing a detection routine for automatically measuring and correcting variations in the number of paper sheets, and then detecting the amount of curls and wrinkles on the uppermost sheet on the tray.

The tray control section 70' repeatedly executes judgment and processing according to the detection routine shown in FIG. 13 at every predetermined detection timing similar to the above-described embodiment shown in FIG.

First, in step 31, when the tray is raised, the drive motor 43
(see FIG. 6) rotates and starts counting pulses output corresponding to the amount of movement of the tray 42.

Next, in step 32, it is determined whether or not the sensor 26 on the side closer to the center of the paper is turned on. If it is turned on, the process advances to step 33, and when that sensor 26 is turned on, The number of pulses C1 (the number of pulses from the lower limit) is memorized and the process proceeds to step 34, where the number of pulses C1 stored in step 33 is read in by the correction value reading routine that will be explained later in Fig. 14. The correction value ΔF of the sensor 26 is added to obtain C', which is stored, and the process then proceeds to step 35.

Further, if the sensor 26 is not turned on in step 32, the process directly advances to step 35.

In step 35, it is determined whether or not the other sensor 25 located near the edge of the paper is turned on. If it is turned on, the process advances to step 36, and that sensor 25 is turned on.
5 is turned on, and proceeds to step 37, where the correction value ΔS of the sensor 25 read by the correction value reading routine explained in FIG. 14 is added to the pulse number 02 stored in step 36. are added to obtain C2', which is stored, and the process then proceeds to step 38.

Further, if the sensor 25 is not turned on in step 35, the process directly advances to step 38.

Then, in step 38, it is determined whether the upper limit detection sensor 66 (see FIG. 8) is turned on or not. If it is not turned on, the process returns to the main routine, and if it is turned on, step 39 , and enter the number of pulses C□ and C2 stored in step 34 and step 37, respectively.
', calculate the difference between C1 and C2, and obtain C to its absolute value.

Next, in step 40, the number of pulses ΔC obtained in step 39 is less than 50 pulses, that is, the amount of curls and wrinkles is O.
It is determined whether the amount is approximately 5 mm and does not affect the copy operation, and if so, an instruction to permit copying is issued in step 41, and if not, in step 4
Proceed to step 2 and check whether the number of pulses C is 50 or more and less than 150 pulses, that is, the amount of curls and wrinkles is about 5 to 15 mm, which puts a slight burden on the conveyance system, but does not affect the copying operation. If so, a command to display a warning is issued in step 43 and copying is permitted, and if not, the process advances to step 44.

Then, in step 44, it is determined whether the number of pulses ΔC obtained in step 39 is 150 pulses or more, that is, the amount of curls and wrinkles is 15 mm or more, which is an amount that is likely to cause jams, folded edges, etc. If so, in step 45 a command is issued to prohibit all copying, and a command is issued to issue a warning display to replace the paper with one that is free from curls and wrinkles, and the process proceeds to step 46.

Further, in step 44, if the number of pulses ΔG is not 150 pulses or more, the process directly proceeds to step 46, where the pulse count is stopped and reset, and then the process returns to the main routine.

FIG. 14 is a flow diagram showing a routine for reading correction values.

When this routine starts, first, in step 51, the paper end sensor 67 (Fig. 8) detects that there is no paper, and the motor 43 rotates in reverse to determine whether or not the tray 42 is descending. If the tray is being lowered, the program returns to the main routine, and if the tray is being lowered, the process advances to step 52, where the motor 43 rotates when the tray is lowered and starts counting pulses output from the pulse generator 47 corresponding to the amount of tray movement. .

Next, in step 53, it is determined whether or not the sensor 26 is off, and if it is off, the process proceeds to step 54, where the number of pulses 03 when the sensor 26 was turned off is memorized, and the step The process proceeds to step 55, and if it is not turned on, the process directly proceeds to step 55.

In step 55, it is determined whether or not the sensor 25 is off, and if it is, the process proceeds to step 56, where the number of pulses 04 when the sensor 25 was turned off is stored, and step 57 If it is not turned off, the process directly advances to step 57.

Then, in step 57, the lower limit detection sensor 62 (the eighth
11. If it is not on, it returns to the main routine. If it is on, it proceeds to step 58, and from the pulse number 03 stored in step 54, as shown in FIG. The correction value ΔF of the sensor 26 is stored by subtracting the reference value Po (the average reference position at which the sensor detects an object) shown in FIG.

Next, in step 59, the reference value PO is subtracted from the pulse number C4 similarly obtained in step 56, and the correction value ΔS of the sensor 25 is stored. When this is completed, pulse counting is stopped and it is reset. and then returns to the main routine.

In each of the embodiments described above, the amount of curl or wrinkles on the paper on the tray 42 is determined when the tray is raised, but it may also be determined when the tray is lowered. In this case, the amount of curl is determined based on the difference in the positions at which the detection signals of the sensors 25 and 26 change from on to off.

Similarly, it is also possible to detect variations in the sensors 25 and 26 when the tray is raised. In this case, the variation in the detection position is corrected based on the difference in the position at which the detection signal of the sensor changes from off to on.

〔Effect of the invention〕

As explained above, according to the present invention, when the difference in height between the top paper stacked on the tray near the edge and the paper at a distance from there exceeds a predetermined amount, various types of Warnings and commands to prohibit operations are issued and displayed, allowing you to easily remove or replace paper that is at risk of jamming or folding before paper feeding begins. This makes it possible to prevent jams, ear leaks, etc. from occurring inside the device.

In addition, if a means for correcting variations in the detection positions of the detectors is provided, variations in individual detectors can be automatically corrected, so paper curls can be corrected without having to adjust the sensitivity of each detector. It is possible to detect wrinkles and wrinkles with higher accuracy.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a plurality of detectors capable of detecting the height of the uppermost sheet stacked on a tray, which is the essential part of this invention, and their vicinity. FIG. 3 is an overall configuration diagram showing an example of a copying machine equipped with a large-volume paper feeder, and FIG. 3 is a plan view showing the positions of a plurality of detectors in FIG. 1 on a plane. FIG. 4 is a schematic diagram showing how light from a light emitting element of a reflective photosensor is reflected on a paper surface and enters a light receiving element. FIG. 5 is a diagram showing the characteristics of the reflective photosensor shown in FIG. 4, FIG. 6 is a perspective view showing the elevating device that raises and lowers the tray of the mass paper feeder 10, and its related parts, and FIG. 7 is a diagram showing the characteristics of the reflective photosensor shown in FIG. FIG. 8 is a schematic diagram showing a large number of sensors for detecting the remaining amount of paper and a lower limit detection sensor provided in the paper feeding device; FIG. Figure 9 is a flowchart showing the detection timing for determining the amount of curls and wrinkles on the paper, and Figure 10 is a flowchart showing the detection routine for determining whether the amount of curls and wrinkles exceeds a predetermined amount. , FIGS. 11 and 12 are schematic diagrams similar to FIG. 1 showing other embodiments of the present invention, and diagrams showing the variation range of reflective photosensors, FIGS. 13 and 14 are similar to FIG. tray control section 70'
FIG. 3 is a flowchart showing a routine for detecting the curl amount of the uppermost sheet while correcting sensor variations and a routine for reading a correction value, which are executed by the printer. 1... Copying machine 10... Mass paper feeder 25
．． 26... Sensor (detector) 40... Lifting device 42... Tray 42a... Bottom surface 43...
Motor 47...Pulse generator 62...
・Lower limit detection sensor 66...Upper limit detection sensor 70.7
0'...Tray control unit P...Paper Pa...Paper surface 1 Figure 3 Figure 4 Figure 5 Figure 5 0mm Distance L 0mm Figure 6 1n Figure 7 Figure 9 Figure 10 Figure 12 Figure 0mm □Distance I2 0mm

Claims (1)

[Scope of Claims] 1. A tray for stacking paper, a means for raising and lowering the tray, and a means for raising and lowering the tray, arranged correspondingly to the vicinity of the end of the upper surface of the paper on the tray and a position at a distance therefrom, respectively. A plurality of detectors each capable of detecting the height of the paper surface by detecting the uppermost paper surface on the tray, and a detection signal of the paper surface by the plurality of detectors changes when the tray is raised or lowered. means for determining the amount of curls and wrinkles on the topmost paper on the tray based on the difference in position, and outputting various warnings and commands to prohibit operations when the difference exceeds a predetermined amount; A paper feeding device characterized by being provided. 2. The paper feeding device according to claim 1, wherein each of the plurality of detectors detects the bottom surface of the tray when the tray is raised or lowered, and the detection position of each detector is determined based on the difference in the position at which each detection signal changes. A paper feeding device characterized in that it is provided with means for correcting variations in the paper feed device.