JPH01231735A - Residual quantity of paper detector for lift type paper feed cassette - Google Patents

Abstract

PURPOSE:To detect residual quantity of paper without requiring a rotary encoder or a counter by providing an operating means for calculating the residual quantity of paper mounted on a lift board based on the magnitude of load current. CONSTITUTION:A lift board 23 to be guided freely and liftably/lowerably through a guide member 22 is provided to a lift type paper feed cassette. Papers 25 to be fed to a copy machine 24 provided with a call-in roller 24a and a feed roller 24b are mounted on the lift board 23. A drive motor 26 controlled through a controller 41 to lift or lower the lift board 23 is arranged at the lower section of the lift type paper feed cassette 21. A transistor 42 is grounded through a load current detecting resistor 45 and connected through an amplifier 46 to the A/D converting section 44a of CPU 44. CPU 44 controls the operation of the drive motor 26 and also serves as a means for detecting the amount of load current flowing through the drive motor 26 and an operating means for calculating the residual quantity of paper 25 mounted on the lift board 23.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a paper remaining amount detection device used in a lift-type paper feed cassette for supplying large amounts of paper to copying machines, laser printers, etc. .

[Conventional technology]

For example, as shown in FIG. 6, a paper remaining amount detection device of a conventional lift-type paper feed cassette is provided so as to be able to move up and down.
1... is placed, a lower limit switch 13 that detects that the lift 1 12 is at the lowest position, and a drive motor 14 that drives the lift plate 12 up and down. . As shown in FIG. 7, the drive motor 14 includes a rotary encoder consisting of a slit disk 15a that rotates integrally with the rotation shaft 14a, and a photosensor 15b fixed to the main body 14b of the drive motor 14. 15 are provided.

Under the control of a control device (not shown), the drive motor 14 moves the lift plate 12 so that the uppermost sheet 11 of the sheets 11 placed on the lift plate 12 reaches the sheet feeding position.
It is in charge of raising and lowering the

Further, when the drive motor 14 raises the lift 1 roll 12 from the lowest position to the sheet feeding position of the paper 11, the rotary encoder 15 outputs a number of pulses corresponding to the amount of rotation. Therefore, the remaining amount of paper 11 has been detected by counting the number of pulses using a counting device (not shown).

[Problem to be solved by the invention]

However, the above-mentioned conventional paper remaining amount detection device for a lift-type paper feed cassette requires a row encoder 15 and a counting device, resulting in a complicated configuration and high manufacturing costs. was.

[Means to solve the problem]

In order to solve the above-mentioned problems, the paper remaining amount detection device for a lift-type paper feed cassette according to the present invention is provided with a lift plate on which the paper to be fed is placed, which is movable up and down, and a lift plate that is driven up and down. a drive motor, load current amount detection means for detecting the amount of load current flowing through the drive motor, and calculation means for calculating the remaining amount of paper placed on the lift plate based on the amount of load current. It is characterized by

[For production]

With the above configuration, a load current corresponding to the remaining amount of paper placed on the lift plate flows through the drive morph, and the load current amount is detected by the load current amount detection means. Based on this load current amount, the calculating means calculates the remaining amount of paper.

Therefore, the remaining amount of paper can be detected without using a low-resolution encoder or a counting device.

〔Example〕

As an embodiment of the present invention, an example of a paper remaining amount detection device for a lift-type paper feed cassette that supplies paper to a copying machine will be described below with reference to FIGS. 1 to 5.

As shown in FIG. 1, the lift-type paper feed cassette 21 includes:
A lift plate 23 is provided which is guided by a guide member 22 so as to be movable up and down. Paper sheets 25 . . . to be supplied to a copying machine 24 equipped with a pull-in roller 24 a and feed rollers 24 b and 24 b are placed on this lift plate 23 .

A drive motor 26 that is a DC motor that drives the lift plate 23 up and down under the control of the control device 41 is provided at the bottom of the lift-type paper feed cassette 21 . A drive pulley 28 for winding and rewinding the belt 27 is attached to the rotation shaft 26a of the drive motor 26.

One end of the belt 27 is fixed to a drive pulley 28, while the other end is fixed to the lift plate 23 via a reversing pulley 29 provided at the top of the lift-type paper feed cassette 21. By transmitting the driving force of the drive motor 26 to the lift plate 23 by the belt 27, the drive motor 2
The lift plate 23 moves up and down as the motor 6 rotates forward and backward.

At the top of the lift-type paper feed cassette 21, there is a lift plate 23.
The uppermost sheet 25 of the sheets 25 placed on...
The upper limit switch 31 detects that the paper 25 placed on the lift plate 23 is in a position where it can be fed by the feed roller 24a of the copying machine 24, and the detector 32a detects when the paper 25 placed on the lift plate 23 reaches A paper-out switch 32 is provided that falls into a hole 23a formed in the lift plate 23 to detect paper-out.Furthermore, below the lift-type paper feed cassette 21, there is provided a paper-out switch 32 that falls into a hole 23a formed in the lift plate 23 and detects paper-out. A lower limit switch 33 is provided to detect this.

As shown in FIG. 2, the drive motor 26 has one terminal connected to the power supply +V, and the other terminal connected to the collector 42c of the transistor 42 in the control device 41. The base 42b of the transistor 42 is connected to the output circuit 43.
It is connected to the 7 CPU 44 via.

Further, the emitter 42a of the transistor 42 is grounded via a load current detection resistor 45, and is also connected to an A/D converter 44a of the CPU 44 via an amplifier circuit 46.

The CPU 44 is further connected with a RAM 47, a ROM 48, and an operation unit 49, which controls the operation of the drive motor 26, and includes a load current detection means for detecting the amount of load current flowing through the drive motor 26, and a load current detection means for detecting the amount of load current flowing through the drive motor 26. It also serves as a calculating means for calculating the remaining amount of sheets 25 placed on the lift plate 23 based on the above information.

In the above configuration, when initializing the control device 41 by performing a simulation in advance, the control device 41 performs operations as shown in FIG. 3, for example.

First, assign the value O to the variable
S2). If the lower limit switch 33 is not in the ON state, the process moves to S3, the drive motor 26 is operated to lower the lift plate 23, and S2 and S3 are repeated until the lower limit switch 33 is in the ON state.

On the other hand, if the lower limit switch 33 is in the ON state in S2, the process moves to S4, and it is checked whether the number of sheets 25... loaded on the lift plate 23 has been input from the operation unit 49, and the number of sheets loaded has been input. Repeat step 84 until Therefore, after placing a known number of sheets 25 .

When the number of sheets 25... is input, the process moves to S5 and the drive motor 26 is activated to raise the lift plate 23. At this time, the drive motor 26 receives a load current corresponding to the load torque, that is, the load current corresponding to the load torque of the paper 25 placed on the lift plate 23.
A load current flows according to the number of sheets. Therefore, a voltage proportional to the load current amount of the drive motor 26 is generated across the load current amount detection resistor 45. After this voltage is amplified by the amplifier circuit 46, it is analog-to-digital converted by the A/D converter 44a of the CPU 44 and stored in the RAM 47 (S6).

Next, whether or not the upper limit switch 31 is in the ON state, that is, the uppermost sheet 25 of the sheets 25 placed on the lift plate 23 is
It is checked whether the paper has been raised to a position where it can be fed by a (S7).

If the upper limit switch 31 is not in the ON state in S7, the process returns to S5 and repeats 85 to S7.

Further, if the upper limit switch 31 is in the ON state in S7, the process moves to S8 and it is checked whether the value of the variable X is O or not.

Since the value of variable X is 0 at first, proceed to S9 and perform the above
The load current amounts stored while repeating steps 5 to S7 are averaged and stored in the RAM 47 as a constant In. In addition, the number of sheets of paper 25 inputted from the operation unit 49 is a constant n,
510), and after counting and amplifying the variable X (Sll), the process returns to S2.

Therefore, the same operation is repeated again in steps 82 to S8. However, in S4, the number of sheets of paper 25 different from the above constant n.
...is placed. Further, in S8, the value of X is counted up and becomes 1, so the process moves to S12.

At step 312, similarly to S9, the load current amount stored while repeating steps 85 to S7 is averaged and stored as a constant 1nz in the RAM.
47, tα is written.

Also, similarly to S10, the number of sheets 25 manually input from the operation unit 49 is stored in the RAM 47 as a constant n2 (513), and the constant 1 obtained as described above is stored in the RAM 47 (513).
Based on the values of nls Inz, n+, and n2, (In
After calculating the value of z In+)/(nz n+) and storing it in the RAM 47 as a variable a, the simulation ends.

After the initial setting of the control device 41 is performed in this way,
When you turn on the power to use the copying machine or when paper 2
5... is replenished, the control device 41 performs the operation shown in FIG.

First, it is checked whether the lower limit switch 33 is in the ON state, that is, whether the lift plate 23 has been lowered to the lower limit position (S21). If the lower limit switch 33 is not in the ON state, the process moves to S22, and the drive motor 26
is activated to lower the lift plate 23, and steps 321 and S22 are repeated until the lower limit switch 33 is turned on.

On the other hand, if the lower limit switch 33 is in the ON state in S21, the process moves to S23 and the drive motor 26 is activated to raise the lift plate 23. At this time, a load current corresponding to the load torque, that is, a load current corresponding to the remaining amount of the sheets 25 placed on the lift plate 23 flows through the drive motor 26. Therefore, a voltage proportional to the load current amount of the drive motor 26 is generated across the load current amount detection resistor 45. This voltage is amplified by the amplifier circuit 46 in the same way as in the case of S6 above, and then analog-to-digital converted by the A/D converter 44a of the CPU 44 and stored in the RAM 47 (S
24).

Next, whether or not the upper limit switch 31 is in the ON state, that is, the uppermost sheet 25 of the sheets 25 placed on the lift plate 23 is
It is checked whether the paper has been raised to a position where it can be fed by a (S25).

If the upper limit switch 31 is not in the ON state in S25, the process returns to S23 and repeats 323 to S25. Also,
If the upper limit switch 31 is in the ON state in S25,
The process moves to S26, and the load current amounts stored while repeating the above steps 823 to S25 are averaged and stored as a variable I in the RAM 4.
Store in 7.

In addition, the constant In obtained by the simulation
+, Inz, nl, and n2, lift plate 2
Assuming that the number of sheets of paper 25... placed on 3 and the amount of load current have a relationship as shown in FIG. 5, the remaining amount of paper 25... when the above load current amount is Number of sheets n
Calculate as = (I In+) /a + nl (527), store this value in the RAM 47 (328),
The remaining amount detection that is performed when the power is turned on or when paper 25 . . . is replenished ends.

The remaining number of sheets of paper 25 obtained in this way is subtracted according to the number of copies, and the number and ratio to the maximum loading amount are displayed to inform the user of the copying machine of the number of sheets of paper 25.・・・
It can be used to notify the remaining amount.

〔Effect of the invention〕

As described above, the paper remaining amount detection device for a lift-type paper feed cassette according to the present invention includes a lift plate that is movable up and down, on which the paper to be fed is placed, and a drive motor that drives the lift plate up and down. , a load current amount detection means for detecting the amount of load current flowing through the drive motor, and a calculation means for calculating the remaining amount of paper placed on the lift plate based on the load current amount.

This allows the remaining amount of paper placed on the lift plate to be detected without using a rotary encoder or counting device, which has the effect of simplifying the configuration and reducing manufacturing costs. .

[Brief explanation of the drawing]

1 to 5 show an embodiment of the present invention, in which FIG. 1 is a cross-sectional front view showing the configuration of a paper remaining amount detection device for a lift-type paper feed cassette, and FIG. 2 is a control device. 3 is a flowchart showing the operations performed by the control device during simulation, FIG. 4 is a flowchart showing the operations performed by the control device when the power is turned on or when replenishing paper, and FIG. 5 is a flowchart showing the operations performed by the control device during simulation. 3 is a graph showing the relationship between the number of sheets placed and the amount of load current of the drive motor. 6 and 7 show conventional examples.
FIG. 7 is a sectional front view showing the structure of the lift-type paper feed cassette, and FIG. 7 is a perspective view showing the structure of a drive motor provided with a rotary encoder. 21 is a lift-type paper feeding cassette, 23 is a lift plate, 25 is paper, 26 is a drive motor, and 41 is a control device (load current amount detection means, calculation means). Patent applicant Sharp Corporation Figure 1 Figure 4 Figure 6 Figure 7 Figure 5a

Claims (1)

[Claims] 1. A lift plate that is movable up and down and on which paper to be supplied is placed; a drive motor that drives the lift plate up and down; and a load current that detects the amount of load current flowing through the drive motor. A paper remaining amount detection device for a lift-type paper feed cassette, comprising: a detection means; and a calculation means for calculating the remaining amount of paper placed on the lift plate based on the load current amount.