JPH0439224A - Sheet carrying device - Google Patents

Abstract

PURPOSE:To start sheet carrying action in a short time by using a fan device with an exhaust fan and a suction fan installed sandwiching a bulkhead and simultaneously rotated by a direct current motor, and controlling revolution speed of the direct current motor to a high revolution speed over a suitable revolution speed until a fixed period from the start of drive of the motor. CONSTITUTION:A fan device 6 has a suction fan 7 and an exhaust fan 8 installed sandwiching a bulkhead and simultaneously rotated by a direct current motor 9. The direct current motor 9 is controlled to a high revolution speed over a suitable revolution speed for a fixed period just after the start of driving it, changed over to the suitable revolution speed after the fixed period elapsed, and controlled. It is possible to set air suction pressure, making a sheet 1 sucked into a carrying means 4, and air feeding flow rate, separating laminated sheets 1, at a suitable value quickly, and to start carrying action of the sheets in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sheet feeding device in a copying machine or the like.

Conventional technology For example, as a sheet feeding device in a conventional copying machine,
It is well known to have a configuration in which laminated sheets are separated by supplying air, the separated sheets are adsorbed onto a belt serving as a conveying means by air suction, and single sheets are fed.

A compressor is usually used to supply air to separate the laminated sheets and to suck air to adsorb the sheets onto the belt.

However, when the above-mentioned compressor is used, it takes several minutes for the air supply flow rate and suction pressure to become constant, which has the disadvantage of delaying start-up.

Therefore, in the sheet feeding devices of recent copying machines, attempts have been made to configure the sirocco fan, which is a cooling fan for the copying machine's heater and drive motor, to also function as a fan for separating laminated sheets and attracting belts. .

Problems to be Solved by the Invention However, in the case of sirocco fans, considering the life of the fan motor and the noise caused by wind noise during its operation,
It is necessary to wait in a stopped state until the copying operation starts, and the sirocco fan is rotated at the same time as the copying start button is turned on, but even in this case, the air supply flow rate and suction pressure are There is a problem in that it takes several seconds to reach the appropriate value, and as a result, the time required for the first copying operation becomes longer.

Therefore, an object of the present invention is to provide a sheet feeding device that can start a sheet feeding operation in a short time.

Means for Solving the Problems The present invention provides a conveying means provided above or below the laminated sheet placed on a table to suck the sheet and send it to a sheet feeding path, and a conveying means provided above or below the laminated sheet placed on a table, and A sheet feeding device including an air supply nozzle that sprays air at a controlled flow rate to separate the sheet sucked by the conveying means from the remaining sheets, an intake fan having a function of causing the conveying means to suck the sheet; An exhaust fan that serves to supply air to the air supply nozzle is arranged in parallel with a partition wall, and the intake fan and the exhaust fan are simultaneously rotated by a DC motor, and the rotation speed of the DC motor. The motor is characterized by comprising a motor rotation speed control means that controls the rotation speed to a predetermined high speed exceeding the appropriate rotation speed for a certain period from the start of motor drive, and controls the rotation speed to the appropriate rotation speed after that certain period. This is a sheet feeding device.

According to the present invention, the DC motor is controlled to a high rotation speed that exceeds the appropriate rotation speed for a certain period of time immediately after the start of driving,
After a certain period of time has elapsed, the rotational speed is switched to an appropriate rotational speed, so the suction pressure of the air that causes the sheet to be sucked into the conveying means and the air supply flow rate from the air supply nozzle that separates the laminated sheets quickly reach the appropriate values, and the rotation speed is controlled in a short period of time. Sheet feeding operation can be started with .

Embodiment FIG. 1 is a longitudinal cross-sectional view showing a schematic configuration of a sheet feeding device which is an embodiment of the present invention.

A laminated sheet 1 in which a plurality of sheets are piled up is placed on a sheet supply table 2 made of an elastic spring or the like,
An upper limit switch 3 is arranged so as to be in contact with the rear portion of the upper surface of the laminated sheet 1. This upper limit switch 3 is a switch for detecting that the upper surface of the uppermost layered sheet 1 is at the height of the upper limit switch 3.

A suction belt 4, which is a conveyance means for suctioning and conveying sheets, is arranged above the sheet supply table 2.

An opening of an intake duct 5 hanging down from above is exposed to the middle part of the suction belt 4, and the intake duct 5 is connected to an intake fan 7 which is one component of the fan device 6.
is connected to the intake lower a.

Air is blown toward the upper front end of the laminated sheet 1 at the front end side of the laminated sheet 1 at the lower position of the suction belt 4, that is, the side where the sheet is sent out by the suction belt 4. An air supply nozzle 11 is arranged which separates the sheet from the remaining sheets. This air supply nozzle 11 is connected via an exhaust duct 12 to an exhaust port 8a of an exhaust fan 8, which is one component of the fan device 6.

Further, on the sheet sending side of the suction belt 4, there is arranged a paper feed path 13 for feeding the fed sheets into the copying machine, and the paper feed path F! Conveyance rollers 14a and 14b for conveying the sheet are provided in the middle of @1B.

The intake fan 7 and exhaust fan 8 of the fan device 6 are as follows:
Covered individually by cases 7b and 8b, case 7
b, 8b are arranged coaxially via a partition wall that is a part of the DC servo motor 9, and both are connected to the output shaft 9a of one DC servo motor 9.

Both the intake fan 7 and the exhaust fan 8 have a plurality of blades 16 arranged radially on a circular bottom plate 15, as shown in FIG. The main body of the structure is surrounded by cases 7b and 8b.

As shown in a perspective view in FIG. 3, the suction belt 4 includes a pair of endless belts 19 between pulleys 18a and 18b.
are wound around pulleys 18a and 18b at intervals in the axial direction, and a large number of ventilation holes 19a that pass through the endless belt 19 in the thickness direction are distributed and formed. The structure is such that the suction force from the intake duct 5 is guided to the endless belt 19 running below.

FIG. 4 is a block diagram showing a connection configuration between the DC servo motor 9 and each circuit that drives and controls the rotation of the motor.

The speed switching circuit 20 is a circuit that outputs a command for switching the rotational speed of the DC servo motor 9. The speed control circuit 21 is a circuit that controls the rotational speed of the DC servo motor 9 in response to a falling speed switching signal S2 provided from the speed switching circuit 20. The drive circuit 22 is a circuit that drives the DC servo motor 9 according to the control signal output from the speed control circuit 21. The inverter 23 is a circuit that converts a part of the control signal output from the speed control circuit 21 into a control signal corresponding to the energization time and supplies it to the drive circuit 22.

The speed control circuit 21 includes a speed discriminator 25 that detects a speed error by comparing a speed signal RE corresponding to the rotational speed of the DC servo motor 9 detected by the rotary encoder 24 with a reference clock signal; charge pump circuit 26 that converts the speed error detected by the generator 25 into a speed control voltage, and the amplifier 2
7. A PWM circuit 28 that converts the speed control voltage obtained by the charge pump circuit 26 into a pulse width modulation signal, and a DC servo motor 9 that detects the pulse width modulation signal obtained by the PWM circuit 28 and the position sensor 29. It is composed of a distribution circuit 30 that distributes and outputs control signals corresponding to the U-phase, ■-phase, and W-phase motor coils based on the rotational phase of the motor coil. The crystal oscillator 31 is an element for generating a reference clock signal used in the speed discriminator 25.

FIG. 5 is a timing chart showing the operation of the sheet feeding device. 5(1) is an on/off command signal S1 output from the speed switching circuit 20 for starting/stopping the speed control circuit 21, and FIG. 5(2) is an on/off command signal S1 output from the speed switching circuit 20. Fig. 5 (3) shows the speed switching signal S2, and Fig. 5 (3) shows the rotation speed of the DC servo motor 9.
4) shows the suction pressure by the intake duct 5, and FIG. 5 (5) shows the sheet feeding start timing for each time.

Next, the operation of the sheet feeding device will be explained with reference to the timing chart shown in FIG.

The outline of its operation is as follows. The rotation of the DC servo motor 9 rotates the intake fan 7 and the exhaust fan 8, and air flows inside the intake fan 7 as shown by the arrow a and inside the exhaust fan 8 as shown by the arrow. As a result, the air pressure in the intake duct 5 decreases, and the uppermost sheet of the laminated sheets 1 is sucked into the suction belt 4. At this time, from the exhaust fan 8 to the exhaust duct 12
The air sent through the air supply 7' is blown onto the front end side of the laminated sheet 1 from the air supply 7' nozzle 11, thereby lifting the topmost sheet and smoothly adsorbing the sheet to the suction belt 4.

The sheet attracted to the suction belt 4 is sent to the paper feed path 13 by the drive of the suction belt 4, and further sent from the paper feed path 13 into the interior of the copying machine by conveyance rollers 14a and 14b.

The start of the sheet feeding operation is performed as follows. When a copy start button (not shown) of the copying machine is turned on, the on/off command signal S1 output from the speed switching circuit 20 becomes high level corresponding to on. At this time, the speed switching signal S2, which is also output from the speed switching circuit 20, is kept at a low level. In response to the low-level speed switching signal S2, the speed control circuit 21 outputs a control signal to rotate the DC turbo motor 9 at the maximum rotation speed N1, and as shown in FIG.
The rotational speed quickly reaches the maximum rotational speed N1 after the start of driving.

As the C servo motor 9 is driven to rotate in this way, the suction pressure by the intake duct 5 on the suction belt 4 also increases rapidly with a little delay from the change in the motor rotation speed, as shown in FIG. 5(4). When a certain period of time T1 has elapsed from the start of driving the DC servo motor 9 until slightly past the point in time when the motor rotation speed reaches the maximum rotation speed N1, the speed switching circuit 2
The speed switching signal S2 outputted from 0 is switched from a low level to a high level. In response to this switching, the speed control circuit 21 outputs a control signal to rotate the DC servo motor 9 at a rated rotation speed N2 that is slightly lower than the maximum rotation speed N1. As a result, the rotation speed of the DC servo motor 9 becomes the rated rotation speed N2 after the above-mentioned fixed period T1, as shown in 5th Ci(3).

During a certain period T1 until the motor rotation speed changes from the maximum rotation speed N1 to the rated rotation speed N2, the suction pressure in the suction belt 4 reaches a value P1 exceeding the specified value P2, and then the motor rotation speed changes to N2. As a result, it drops to the specified value P2 and settles down (.

Although not shown in FIG. 5, the supply flow rate of the air blown out from the air supply nozzle 11 also settles down to the specified value after a certain period of time T1 in a similar manner to the above-described suction pressure.

When a period T2 or a slightly longer period T3 elapses from the start of motor drive until the suction pressure in the suction belt 4 settles to the specified value P2, the suction belt 4 starts to be driven and the first sheet that has been sucked is removed. The paper is sent to the paper feed path 13, and further transported to the transport rollers 14a, 14. b
is sent to the inside of the copier by If the number of copies is set to a plurality of times, the same sheet feeding operation is sequentially repeated the set number of times each time one copy is completed. When the number of copies is two, when the second sheet feeding operation by the suction belt 4 is completed, both the on/off command signal S1 and the speed switching signal S2 return from the high level to the low level. The speed control circuit 21 then stops. As a result, the drive of the DC servo motor 9 is stopped, and the suction pressure in the suction belt 4 is also returned to its original state.

Effects of the Invention As described above, the sheet feeding device of the present invention uses a fan device in which an exhaust fan and an intake fan, which are arranged in parallel through a partition wall, are simultaneously rotated by a DC motor. The rotational speed of the motor is controlled by ffII to a high rotational speed that exceeds the appropriate rotational speed for a certain period of time from the start of motor drive,
After a certain period of time, the rotation speed is controlled to an appropriate value, so the suction pressure of the air that causes the sheet to be sucked into the conveying means and the air supply flow rate from the air supply nozzle that separates the laminated sheets quickly reach the appropriate values. , the sheet feeding operation can be started in a short time.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing a schematic configuration of a sheet feeding device that is an embodiment of the present invention, FIG. 2 is a perspective view showing the configuration of a fan main body in the sheet feeding device, and FIG. 3 is a sheet feeding device. A perspective view showing the configuration of a suction belt in a feeding device,
FIG. 4 is a block diagram showing the NQ configuration of a DC servo motor drive circuit and a control circuit in the sheet feeding device, and FIG. 5 is a timing chart showing the operation of the sheet feeding device. 1... Laminated sheet, sheet supply stand, 4... Suction belt, 5... Intake duct, 6... Fan device, 7...
Intake fan, 8. Exhaust fan, 9... DC servo motor, 11. Air supply nozzle, 12. Exhaust duct, 20.
Speed switching circuit, 21 Speed control circuit, 22 Drive circuit Agent Patent attorney Keiichi Nishikyo

Claims (1)

[Scope of Claims] A conveying means provided above or below the laminated sheet placed on a table to suck the sheet and send it to the sheet feeding path, and a conveying means that controls the flow rate of the laminated sheet from one end side. an air supply nozzle that sprays and separates the sheet sucked by the conveyance means from the remaining sheets; A fan device in which an exhaust fan responsible for supplying air is installed in parallel via a partition wall, and the intake fan and the exhaust fan are simultaneously rotated by a DC motor; A sheet feeding device comprising: a motor rotation speed control means for controlling the motor rotation speed to a predetermined high speed exceeding the appropriate rotation speed for a certain period of time, and controlling the motor rotation speed to the appropriate rotation speed after the certain period.