JPH08169568A - Control device of raising-lowering type paper feeding tray - Google Patents

Abstract

PURPOSE: To maintain a stopping position of a paper sheet of the uppermost layer constant by measuring an electric current flowing to a driving motor in a process that a paper feeding tray rises, recognizing a load corresponding to a quantity of paper sheets, setting motor driving correcting time according to the load, and stopping the driving motor after preset time passes after the paper sheet of the uppermost layer is detected. CONSTITUTION: At rising time of a paper feeding tray on which a loading quantity of paper sheets changes in a paper feeding process, a value of an electric current flowing to a driving motor 23 is read, and it is compared with a value by applying a prestored electric current value at no-load time. A loading quantity of paper sheets at that time is found from a difference between both, and a value of motor stop correcting time T changing according to the loading quantity is searched from a table stored in a RAM 40. The driving motor 23 is stopped after the time T passes after an upper limit sensor 33 is turned on by a corresponding value. Therefore, a stopping position of the paper sheet of the uppermost layer can be maintained constant regardless of a quantity of paper sheets on the paper feeding tray.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a lifting type paper feeding tray.

[0002]

2. Description of the Related Art In a copying machine or a printer, a paper feed tray on which a large number of paper sheets are stacked is sequentially raised, and the paper sheets on the paper feed tray are fed by a paper feed roller in order from the uppermost one. There is a large paper feeder. For example, as described in Japanese Utility Model Application Laid-Open No. 2-132030, when a paper feed tray (recording paper placing table) is raised to a position where paper can be fed, the state is detected by an upper limit sensor, and this upper limit is detected. There is a large-volume sheet feeding device in which a motor is stopped together with a sheet feeding tray according to a detection signal of a sensor. Further, as described in JP-A-2-144351, the weight of the paper is detected by a pressure sensor provided on an ascending / descending paper feed tray (paper loading plate), and the output of this pressure sensor and the paper feed There is a paper supply device that calculates the remaining amount of paper on the paper feed tray based on the number of sheets. Furthermore, the actual Kaihei 2-806
As described in Japanese Patent Laid-Open No. 35-35, a switch is turned on to allow a rising operation of the paper feed tray when the transfer paper stacked on the paper feed tray (bottom plate) that moves up and down is covered with an outer cover, When the tray rises to a position where it can be fed together with the transfer paper, and further raises it, the cover is opened with the transfer paper and the switch is turned off to prohibit excessive movement of the paper feed tray. There is a large capacity tray.

[0003]

In the above-described paper feeding apparatus, generally, the paper feeding tray is driven upward as the remaining amount of the paper sheets stacked on the paper feeding tray decreases, and the uppermost paper sheet is fed. A structure is adopted in which the sensor detects the state when the paper feed position is reached and the paper feed tray is stopped by the detection signal, but the drive motor for raising and lowering the paper feed tray is turned off. Also rotates by a certain angle due to inertia and then stops. The inertia at this time varies depending on the amount of paper sheets on the paper feed tray. In particular, in the case of a paper feed tray on which a large number of paper sheets are stacked, the difference in the load due to the difference in the amount of paper leaves is large, so that the position at which the paper feed tray is stopped varies. This variation appears as a variation in the contact pressure between the sheet on the sheet feeding tray and the sheet feeding roller, and there is a problem that the sheet feeding performance is affected.

[0004]

SUMMARY OF THE INVENTION According to the present invention, there is provided a paper feed tray which is supported below a paper feed roller so as to be able to move up and down, a drive motor which rotates the paper feed tray in a forward and reverse direction, and the paper feed tray. A lower limit sensor for detecting the lowest descent position of the sheet, an upper limit sensor for detecting the uppermost sheet of the sheet on the sheet feed tray when the sheet feed tray is raised, and a detection signal of the lower limit sensor and the upper limit sensor. A drive circuit that drives the drive motor, a current measuring unit that measures a current value that flows in the drive motor, and a current value that flows in the drive motor according to a stacking amount of the sheets on the paper feed tray. Motor stop correction time setting means for setting the motor stop correction time,
A control device for an elevating type paper feed tray, which is configured by a motor drive time correction unit that corrects the time from when the upper limit sensor outputs a detection signal to when the drive motor is stopped based on the motor stop correction time. .

[0005]

According to the present invention, the current flowing through the drive motor is measured by the current measuring means in the process of raising the paper feed tray by the drive motor until the upper limit sensor detects the uppermost sheet, and the measured current is measured. It is possible to recognize the load corresponding to the amount of sheets on the paper feed tray from the value. Also,
Depending on the recognized load, the motor drive correction time from the detection of the upper limit sensor to the stop of the drive motor is set by the motor drive correction time setting means, and the upper limit sensor moves the uppermost sheet to the uppermost sheet by raising the paper feed tray. When detected, the drive motor is stopped by the motor drive time correction means after the motor drive correction time corresponding to the changing load elapses. The stop position is kept constant.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. First, FIG. 2 shows the internal structure of the copying machine 1. A contact glass 4 supporting an original document (not shown) pressed by the pressure plate 3 is provided on the upper part of the apparatus main body 2, a light source 5 for illuminating the original document on the contact glass 4, and a plurality of mirrors for reflecting the original image. There is provided a scanner 9 having the numbers 6, 7 and 8 and reciprocally driven in the horizontal direction by a scanner motor (not shown). Further, a lens 10 for converging an image reflected by the mirror 8 and a plurality of mirrors 12, 13, 14 for reflecting an image passing through the lens 10 on the photoreceptor 11.
Are provided.

On the outer circumference of the photoconductor 11, a charging roller 15 for uniformly charging the outer circumference of the photoconductor 11 and a photoconductor 11 are provided.
Developing unit 16 for developing the electrostatic latent image formed by forming the reflected image from the mirror 14 on the charged portion of the
The transfer belt 17, the cleaning unit 18 for cleaning the surface of the photoconductor 11, and the eraser 19 for erasing the charge on the photoconductor 11 are arranged.

Further, a paper feed tray unit 20 is provided below the apparatus main body 2. The paper feed tray unit 20 includes a paper feed tray 22 on which a large number of paper sheets (transfer paper) 21 are stacked, and a drive motor (DC motor) that drives the paper feed tray 22 and can rotate in the forward and reverse directions. 23,
A paper feed roller 24 that sends out the uppermost paper leaf 21 on the paper feed tray 22, a conveyance roller 25 that conveys the paper leaf 21 delivered from the paper feed roller 24, and this conveyance roller 25.
When the sheet 21 is contacted with the sheet 21 and the sheet 21 is double-fed, the reverse roller 26 returns the sheet 21 of the next layer and below. Paper feed path 2 connecting the transport roller 25 and the lower part of the photoconductor 11
7, a registration sensor 28 that detects the paper sheet 21 and a registration roller 29 that conveys the paper sheet 21 in synchronization with the rotational movement of the photoconductor 11 are provided. Further, the apparatus main body 2 includes a fixing unit 30 for fixing the transferred image transferred from the transfer belt 17 onto the fed paper sheet 21, and a paper discharge tray 31 for discharging the fixed paper sheet 21. It is provided.

Further, the paper feed tray unit 20 is provided with a lower limit sensor 32 for detecting a state where the paper feed tray 22 has reached a certain lowermost position (home position), and above the lower limit sensor 32. 3 and 4
A light transmission type upper limit sensor 33 as shown in FIG. That is, an arm 35 is rotatably held by a drive shaft 34 on which the transport roller 25 is driven, the paper feed roller 24 is rotatably fitted to an end portion of the arm 35, and an arm 35 is provided at a central portion. A transmission body (gear) 36 that transmits the rotation of the transport roller 25 to the paper feed roller 24 is rotatably held. Further, the arm 35 is fixedly provided with a light blocking piece 37 for blocking the optical axis between the light emitting element 33a and the light receiving element 33b of the upper limit sensor 33.

As shown in FIG. 4A, when the paper feed tray 22 is in the lower position, the arm 35 rotates about the drive shaft 34 so that the paper feed roller 24 is in the lower position. At this time, the upper limit sensor 33 keeps the OFF state because the optical axis is shielded by the light shielding piece 37, and as shown in FIG. 4B, the paper feed tray 22 is raised and the uppermost paper sheet 21 is supplied. When the paper roller 24 is pushed up, the light blocking piece 37 is retracted downward by the clockwise rotation of the arm 35 about the drive shaft 34, and the upper limit sensor 33 is turned on.

FIG. 5 is a block diagram showing an electronic circuit for raising and lowering the paper feed tray 22. That is, the ROM 38 in which fixed data such as a program is written
And a CPU 39 for executing the program in the ROM 38,
A RAM 40 for temporarily storing variable data is connected by a system bus 41. The RAM 40 has a function of storing a table in which a motor stop correction time corresponding to a change in a current value flowing in the drive motor 23 according to a stacking amount of the paper sheet 21 on the paper feed tray 22 is set. Is. This table will be described in detail later. In addition, the lower limit sensor 32 and the upper limit sensor 33.
And an operation panel 42 provided on the apparatus main body 2 are connected to the CPU 39 via a gate array 43. Further, a drive circuit 44 for driving the drive motor 23 based on the detection signals from the lower limit sensor 32 and the upper limit sensor 33, and a calibration switch 45 are provided in the CPU.
It is connected to 39. Furthermore, a gate array 43,
A power supply 46 that supplies a driving voltage to the CPU 39 and the drive circuit 44 is provided.

Next, FIG. 6 shows a part of the control board 47.
The ROM 38 and RAM 40, the CPU 39, the gate array 43, the drive circuit 44, etc. are mounted on the control board 47. The drive motor 23, the lower and upper limit sensors 32 and 33, and the calibration switch 45 are connected via the control board 47. In the figure, AN _{0 to} AN _m indicate input ports of the control board 47, and PC _{0 to} PC _m indicate output ports. V _AA is the supply voltage. The calibration switch 45 has two switches SW1 and SW2 for selecting a signal input.

In such a structure, the paper feed tray 22
The load of the drive motor 23 that raises and lowers the paper sheet 21 to be loaded
Depends on the amount of. The load is determined by measuring the current flowing through the drive motor 23 by a current measuring means (not shown), but the relationship between the load and the current varies greatly depending on the drive motor 23 used. Therefore, the relationship between the current flowing through the drive motor 23 and the load is measured for each copying machine 1 and stored in the RAM 40. This operation is performed in the adjustment process in the manufacturing process of the copying machine 1.

The operation will be described below with reference to the flow chart shown in FIG. First, the switch SW1 of the calibration switch 45 is turned on (SW1 = 1). CPU39
Recognizes this state in step (indicated by st. In the figure) 21, and in step 22, the drive motor 23 is rotated in the reverse direction to lower the paper feed tray 22 toward the home position. When the paper feed tray 22 reaches the home position, the lower limit sensor 32 is turned on (HP = 1). Therefore, when this state is recognized in step 23, step 24
In step 25, the drive motor 23 is stopped, and in step 25, a predetermined storage area (τ _SL , τ _SH ) in the RAM 40 is cleared. Then, in step 26, the drive motor 2
3 is rotated in the normal direction to raise the paper feed tray 22. Step 2
7, the current value τ _SL flowing through the drive motor 23 in the process of raising the paper feed tray 22 is measured and the measured value is stored in the RAM 40.
To memorize. This current value τ _SL is a value when nothing is placed on the paper feed tray 22. And step 28
In step 29, when the upper limit sensor 33 recognizes that the upper limit sensor 33 is turned on (LP = 1), the drive motor 23 is reversed in step 29 to lower the paper feed tray 22, and the lower limit sensor 32 is turned on (HP) in step 30. = 1), the drive motor 23 is stopped in step 31.

Next, a predetermined heavy object (10 kg in this embodiment) is placed on the paper feed tray 22, and the calibration switch 4 is placed.
The switch SW2 of No. 5 is turned on (SW2 = 1). This switch operation is recognized in step 32, and the drive motor 23 is rotated in the normal direction in step 33 to feed the paper feed tray 2.
Raise 2. In step 34, the current value τ _SH flowing through the drive motor 23 in the course of raising the paper feed tray 22 is measured and stored in the RAM 40, and in step 35, the upper limit sensor 33 is turned on (LP = 1). After recognizing the state, in step 36, the drive motor 23
Reverse to lower the paper feed tray 22, and step 37
After recognizing that the lower limit sensor 32 is turned on (HP = 1) at step 38, the drive motor 2
Stop 3.

Next, at step 39, the paper feed tray 2
The constant k obtained by dividing the difference between the current values τ _SL and τ _SH by the weight of the above-mentioned heavy object placed on the memory 2 is stored in the RAM 40. This constant k
Is the value of current flowing through the drive motor 23 per unit weight. Subsequently, in step 40, the value I _ME obtained by calculating the product of the standard value PE for determining the shortage of the paper sheet 21 on the paper feed tray 22 and the constant k described above is stored in the RAM 40, and step 41 At R, the value I _ML obtained by calculating the product of the standard value PL for determining the overload on the paper feed tray 22 (the state in which the number of paper sheets 21 is too many) and the constant k described above is R.
Store in AM40.

Next, the process of actually using the copying machine 1 adjusted at the time of manufacturing as described above will be described. First, an outline will be given. The process executed here is to read the current value I _MD flowing through the drive motor 23 when the paper feed tray 22 is moved up in which the stacking amount of the paper sheets 21 changes during the paper feed process, and when there is no load stored in step 27 in the flowchart of FIG. The current value τ _SL is applied to the value I _MS to find the difference (that is, the stacking amount of the paper sheets 21 on the paper feed tray 22 at that time) τ ₀ , and the table 48 stored in the RAM 40. The value of the motor stop correction time T that changes according to the load amount τ ₀ at that time is searched from (see FIG. 7), and after the motor stop correction time T elapses after the upper limit sensor 33 is turned on by the corresponding value. The drive motor 23 is stopped. That is, the table 48 functions as a motor stop correction time setting unit that sets the motor stop correction time corresponding to the current value flowing in the drive motor 23 according to the stacking amount of the paper sheets 21 on the paper feed tray 22. In this table 48, the range of the loading amount τ ₀ at each time is divided into five stages, and the value of the motor stop correction time T is given to each of the divided ranges.

Such a correction process will be sequentially described with reference to the flowchart of FIG. When the power switch is turned on, after this state is recognized in step 1, the upper limit sensor 33 is turned on (LP
= 1) is determined. If it is determined to be on, the paper feed tray 22 has reached the paper feed position, so in step 3, the drive motor 23 is reversed to lower the paper feed tray 22 toward the home position, and in step 4, the lower limit sensor 32 is turned on. After recognizing the state where (HP = 1), the drive motor 23 is stopped in step 5. Then, raising the paper feed tray 22 is rotated forward to drive motor 23 in Step 6, to measure the current value I _MD flowing in the drive motor 23 in this process, and stores the current value I _MD in RAM40 in step 7 , Step 8
In step 1, the no-load current value τ _SL which has been set at the time of manufacturing the copying machine 1 is called and stored in the RAM 40 as I _MS , and in step 9, the difference between I _MD and I _MS is calculated,
The result is stored in the RAM 40 as the stacking amount τ ₀ of the sheet 21 on the sheet feeding tray 22 at that time.

Next, I _ML set in step 41 of FIG. 8, that is, the current value I _ML flowing through the drive motor 23 when the stacking amount of the paper sheets 21 on the paper feed tray 22 exceeds a certain value, It performed at step 10 the comparison between (I _MD -I _MS). Here, (I _MD -I _MS) when determines that exceeds the I _ML is driven in step 11 the motor 2
3 is stopped and an overload warning is displayed in step 12. This display is performed using the operation panel 42.

[0021] In step 10, (I _MD -I _MS) is when it is determined to be smaller than I _ML, I _ME set in step 40 in FIG. 8, i.e., the paper feed tray 22
The current value I _ME flowing through the drive motor 23 under the condition that the stacking amount of the upper paper sheets 21 is determined to be insufficient, and (I _MD −
I _MS ) is compared in step 13. here,
(I _MD -I _MS) is when it is determined to be less than I _ME, the process proceeds to step 15 performs a paper shortage displayed in step 14. The display at this time is also performed using the operation panel 42. In step 12, ( _IMD- I
_If it is determined that _MS ) is larger than I _ME , step 15
Move to In step 15, the state of the upper limit sensor 33 is confirmed. Since the upper limit sensor 33 is turned on (LP = 1) when the ascending paper feed tray 22 has reached a certain value, the drive motor 23 is immediately stopped in the conventional case. Load on tray 22 τ ₀
Since There has been grasped in the previous calculation result (I _MD -I _MS), in step 16, it retrieves the value of the motor stop correction time T that varies depending from the table 48 to the load amount tau ₀ at that time, A corresponding value is set in a timer (not shown). The drive motor 23 continues to be driven while the set motor stop correction time T elapses. And step 1
In step 7, after it is determined that the motor stop correction time T has expired, in step 18, the drive motor 23
To stop.

Note that step 7 in FIG. 1 and steps 27 and 34 in FIG. 8 correspond to current measuring means.
Further, step 10 and steps 13 to 18 in FIG. 1 correspond to the motor drive time correction means.

In the above embodiment, the table 48 is used as the motor stop correction time setting means, but the motor stop correction time may be calculated according to the detected stacking amount of the paper sheet 21.

[0023]

According to the present invention, the current flowing through the drive motor is measured by the current measuring means in the process of raising the paper feed tray by the drive motor until the upper limit sensor detects the uppermost sheet, and the measured value is measured. It is possible to recognize the load corresponding to the amount of paper sheets on the paper feed tray from the current value. Further, the motor drive correction time setting means sets the motor drive correction time from when the upper limit sensor is detected to when the drive motor is stopped according to the recognized load. When it detects a leaf,
The drive motor can be stopped by the motor drive time correction means after the motor drive correction time corresponding to the changing load has elapsed. Thereby, the stop position of the uppermost paper sheet can be maintained constant regardless of the number of paper sheets on the paper feed tray. Therefore, the paper sheet can always be reliably fed.

[Brief description of drawings]

FIG. 1 is a flowchart showing a motor drive time correction process according to an embodiment of the present invention.

FIG. 2 is a front view showing the internal structure of a copying machine used as an embodiment of the present invention.

FIG. 3 is a perspective view showing a structure of a sheet feeding / conveying system and an upper limit sensor.

FIG. 4 is a front view showing the operation of the upper limit sensor.

FIG. 5 is a block diagram showing an electronic circuit for raising and lowering a paper feed tray.

FIG. 6 is an explanatory diagram showing a part of a control board.

FIG. 7 is an explanatory diagram showing the contents of a table.

FIG. 8 is a flowchart showing a data setting process in the manufacturing process of the copying machine.

[Explanation of symbols]

 21 paper sheet 22 paper feed tray 23 drive motor 24 paper feed roller 32 lower limit sensor 33 upper limit sensor 44 drive circuit 48 motor stop correction means setting means st. 7, 27, 34 current measuring means st. 10, 12 to 18 motor drive time Correction means

Claims (1)

[Claims] 1. A paper feed tray which is supported below a paper feed roller so as to be able to move up and down, a drive motor which rotates the paper feed tray in a forward and reverse direction, and a lower limit for detecting the lowermost position of the paper feed tray. A sensor, and an upper limit sensor that detects the uppermost paper sheet on the paper feed tray when the paper feed tray is raised,
A drive circuit that drives the drive motor based on the detection signals of the lower limit sensor and the upper limit sensor, a current measuring unit that measures a current value flowing in the drive motor, and a stacking amount of the sheets on the paper feed tray. Motor stop correction time setting means for setting a motor stop correction time corresponding to the current value flowing in the drive motor according to the above, and the drive motor from the time when the upper limit sensor outputs a detection signal based on the motor stop correction time. And a motor drive time correction means for correcting the time until the sheet feeding is stopped.