JPH10265067A - Feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a feeder which can reduce a noise by applying an air jetting device for carrying out the tip separation of the carried part and a vacuum device for feeding a manuscript by the sucking force of an air while sucking a carried part. SOLUTION: By installing the blade of a fan 5 for air supply and the blade of a fan 14 for air sucking with the same shape on the drive shaft 16 of one motor 15, the installation angle of the blades of both fans for the drive shaft 16 is shifted by 1/2 pitch substantially in a periphery direction. Thereby, both fans deny and reduce the noise mutually by the generation of the vibration of a sine wave shifted by 1/2 wavelength mutually.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for an automatic document feeder which separates and feeds a leading end portion of a conveyed object such as a loaded document or transfer paper by blowing air, and an intermediate tray of a duplex copying machine. The present invention relates to a feeding device applicable as an air separation sheet feeding device.

[0002]

2. Description of the Related Art An image forming apparatus such as a copying machine, a plain paper facsimile, a laser printer, or the like uses an automatic document feeder that separates and feeds a leading end portion of a conveyed object such as a loaded original or transfer paper. Have been. A conventional automatic document feeder of, for example, a copying machine is located near the operator because it is located above the copying machine, and the noise of the automatic document feeder is large even if the copying machine itself has low noise.

The document transport speed of the automatic document feeder is such that the document must be replaced while the scanner of the copying machine finishes reading the document and returns to the home position.
In general, the speed is at least two to three times the transfer speed of the transfer paper of the copying machine body. Therefore, the noise of the automatic document feeder is often higher than the noise of the copying machine.
In particular, in the case of an ultra-high-speed copying machine, the air separation method may be adopted because the separation method of the document damages the document in the case of frictional separation. In this case, since the centrifugal fan used for air separation rotates at high speed, noise is generated as if a vacuum cleaner was used.

Conventional examples of such noise reduction are disclosed in Japanese Patent Application Laid-Open Nos. 6-8581 and 7-40630.
As disclosed in Japanese Unexamined Patent Publication, there is a method in which the sound of a fan is collected by a microphone, the sound is converted into an opposite phase, output from a speaker, and the sound is canceled.

[0005]

However, this method is excellent as a principle of silencing, but requires a microphone, a control device for generating an opposite phase, a speaker, and the like, and the device is expensive and complicated.

In Japanese Patent Application Laid-Open No. Hei 7-168514,
A plurality of fans are controlled independently by PWM (pulse width modulation). In this case, however, the fans are operated intermittently, and are effective when a small amount of air is not required, such as when a copying machine is in a standby state. However, in the case of a vacuum device, the use of the intermittent operation is useless.

Further, Japanese Patent Application Laid-Open No. 8-123264 discloses that
The noise of fans and ducts is absorbed by installing a resonator, but the sound-absorbing principle is excellent, but the size of the machine cannot be reduced because it takes up space for the resonator.

FIGS. 13 to 17 show an air separating and feeding mechanism of a conventional automatic document feeder and its operation.
In FIG. 13, there are two flows of air: a flow A of an air ejecting device 102 for separating the leading end of the original 1 and a flow B of a vacuum device 103 for feeding the original 1 while sucking the original.

The air injection device 102 includes a blower device 104
Centrifugal fan 105 (contained in fan casing 106, see FIG. 17), nozzle casing 107,
It is composed of an air knife nozzle 108 and the like. The vacuum device 103 includes a rubber feed belt 112 having a large number of air holes 111 driven by rollers 109 and 110,
It comprises a vacuum tank 113 arranged inside the feeding belt 112 and a centrifugal fan 114 of the blower device 104.

In FIG. 13, the air appears to be circulating at first glance, but the air injection of the flow A and the vacuum of the flow B are separate systems and are not circulating. The blower device 104 that generates wind is a motor shaft 116 of one blower motor 115.
(See FIG. 17) from both sides, and the centrifugal fans 105 and 114 are fixed to the motor shaft 116.

The feeding belt 11 of the vacuum tank 113
A hole is opened in the portion covered by the blower device 10.
4 works, the original 1 passes through the air holes 111 of the feeding belt 112.
01 is sucked, and the feeding belt 112 is rotated by the rollers 109 and 110 in this state to convey one document 101. The feeding belt 112 is arranged so as to suck the center of the document 101 when the document 101 is set.

FIG. 14 shows a shutter 117 of the vacuum device 103. The shutter 117 opens and closes at a timing when a shutter solenoid 118 is turned on and off, and controls the operation of the vacuum device 103. When the shutter solenoid 118 is not working, the shutter 117 is closed in a broken line state, and the shutter 117 is closed.
When the shutter is closed in the state indicated by the broken line, vacuum is not applied, but when the shutter solenoid 118 is turned on and comes to the position indicated by the solid line, vacuum is applied.

Referring to FIGS. 15 and 16, separation and feeding of the document 101 will be described. The document 101 is supplied to a feeding belt 11 of a vacuum tank 113 which is a part of a document table.
Set on 2. At first, the shutter 117 of the vacuum device 103 is closed so that suction is not performed. When a start switch (not shown) is pressed, the blower motor 115 starts rotating, and the air injection device 102 starts working. Then, air is jetted from the air knife nozzle 108 toward the center of the end face of the document 101. As a result, air is blown between the originals 1 and separated. Enough manuscript 1
When 01 is separated, the shutter 117 of the vacuum device 103 is opened by the operation of the solenoid 118, and the lowermost document 101 is attracted to the surface of the feeding belt 112.

Next, a paper feed motor (not shown) rotates,
The original 1 is transported to the pair of paper feed rollers 119 by rotating the feed belt 112 in the direction of the white arrow. When the document 101 is conveyed to the sheet feeding roller pair 119 as shown in FIG. 16, the shutter 117 closes again to stop suction. The feed motor also stops. If the original is sucked, the original 101 is forcibly fed while being peeled off from the feeding belt 112, and the original 101 is damaged. In addition, if the paper feed motor is kept rotating, the originals 101 are fed one after another without permission, causing a jam. Therefore, the shutter solenoid 118 and the paper feed motor operate at a certain timing.

Thus, in the vacuum device 103,
The wind is not exhausted from the centrifugal fan 114 when the document 101 is sucked and when the shutter 117 is closed. Therefore, if air is circulated by one centrifugal fan, the injection of air becomes unstable. Therefore, two centrifugal fans are used and two systems of air flow are required. This is because the air injection needs to be always constant.

FIG. 17 shows a conventional blower device 104 having a blower motor 115 and a motor shaft 116 and two centrifugal fans 105 and 114 for injection and vacuum. The blower motor 115 is fixed to the motor bracket 121 via a vibration-proof rubber 120 with a screw 122 to block vibration. The motor bracket 121 is fixed to an automatic document feeder (not shown) with screws 123.
The two centrifugal fans 105 and 114 are fixed to a motor shaft 116 protruding from both sides of a motor 115. The tip of the motor shaft 116 is threaded, and the centrifugal fan 1
05 and 114 are screwed with set screws 125 via spacers 124.

By the way, in such a conventional apparatus, since the blower device 104 rotates at a high speed of 7000 rpm,
The wind noise of the fan is loud. Also, two centrifugal fans 1
Because of the attachment of 05 and 114, twice as much acoustic energy is generated as compared to the case where only one centrifugal fan is provided.

Accordingly, the present invention has been made to solve the above-mentioned problems, and an air separation system is used to separate a leading end of a conveyed object by blowing out air, and to feed a document while adsorbing a document by suction of air. It is an object of the present invention to provide a feeding device which can reduce noise by utilizing a vacuum feeding device, and which can be provided in a small space at a low cost.

[0019]

According to a first aspect of the present invention, there is provided an air ejecting apparatus for separating a leading end of a conveyed object by blowing air, and a vacuum feeding apparatus for feeding a document while sucking a document by suction of air. A blower, and a blower connected to the air injection device and the vacuum feeder, respectively, for supplying air and sucking air, the blades of a fan for air supply of the blower and the air suction of the blower. The blades of the fan are attached to both ends of the drive shaft of one motor, and the blades of the air supply fan and the air suction fan are the same, and the blades of the air supply fan and the air suction to the drive shaft are used. The mounting angle of the blades of the fan is shifted substantially 1/2 pitch in the circumferential direction.

According to the first aspect of the present invention, the blades of the air supply fan of the blower and the blades of the air suction fan of the blower are attached to both ends of the drive shaft of one motor. The same blade is used for the blade for air suction and the blade for air suction, and the mounting angle of the blade for air supply and the blade for air suction to the drive shaft is substantially 1/2 pitch in the circumferential direction. It has been shifted. Utilizing the air injection device and the vacuum feeding device, the fan of the air blowing device and the fan of the vacuum blowing device are halved each other.
Vibration (sound) of a sine wave having a wavelength shift is generated, and the noises cancel each other out, whereby the noise can be reduced.
Therefore, space saving and noise reduction can be achieved at low cost.

According to a second aspect of the present invention, there is provided an air ejecting apparatus for separating a leading end of a conveyed object by blowing air, a vacuum feeding apparatus for feeding a document while sucking a document by an air suction force, and an air ejecting apparatus. In a feeding device including a first blower device connected to the device and a vacuum feeding device for supplying air and a second blower device for suctioning air, the first blower device and the second blower device have the same structure. Having an intake duct connected to the first blower device and an exhaust duct connected to the second blower device, and each end of the intake duct and the exhaust duct having the same rotational speed. The openings are located in the same plane, and the openings at the ends are arranged adjacent to each other and are oriented in the same direction. The length of the intake duct and the length of the exhaust duct are equal to those of the first blower device and the second blower device. Main frequency Wherein the difference between an odd multiple of the half wavelength of the are set.

According to the second aspect of the present invention, the first blower device and the second blower device have the same structure and the same rotational speed, and the end openings of the intake duct and the exhaust duct are the same. It is located on a plane, the openings at the ends are arranged adjacent to each other, and faces in the same direction. The length of the intake duct and the length of the exhaust duct include the main frequency generated by the first blower device and the second blower device. Is set to an odd multiple of a half wavelength of the wavelength. By utilizing the duct of the air injection device and the duct of the vacuum feeding device, noise can be canceled out at each end opening of the intake duct and the exhaust duct, thereby reducing the noise. Therefore, space saving and noise reduction can be achieved at low cost.

According to a third aspect of the present invention, there is provided an air ejecting device for separating a leading end of a conveyed object by blowing air, a vacuum feeding device for feeding a document while sucking a document by an air suction force, and an air ejecting device. In a feeding device comprising a first blower device connected to the device and a vacuum feeding device for supplying air and a second blower device for suctioning air, an intake duct connected to the first blower device,
An exhaust duct connected to the second blower device,
Each end opening of the intake duct and the exhaust duct is in the same plane, and the end openings are arranged adjacent to each other and oriented in the same direction, and the rotation speeds of the first blower device and the second blower device are stepwise. And the length of the intake duct and the length of the exhaust duct are changed by the variable number of rotations of the first blower device and the second blower device, and the length of the main airflow generated by the first blower device and the second blower device is changed. Set the difference to an odd multiple of half the wavelength of the frequency,
Control means for switching the duct length is provided for each rotation speed of the first blower device and the second blower device.

According to the third aspect of the present invention, the end openings of the intake duct and the exhaust duct are in the same plane, the end openings are arranged adjacent to each other, and are oriented in the same direction. The number of rotations of the blower device and the second blower device can be changed stepwise,
The length of the intake duct and the length of the exhaust duct are changed by the variable number of rotations of the first blower device and the second blower device so that the wavelength of the main frequency generated by the first blower device and the second blower device becomes smaller. Control means for switching the duct length for each rotation speed of the first blower device and the second blower device, which is set to a difference of an odd multiple of a half wavelength, is provided. Utilizing the duct of the air injection device and the duct of the vacuum feeding device, when the rotation speed of the blower device is changed stepwise according to the number of documents and the amount of air blown is changed stepwise, In addition, even if the duct length is switched, noise can be canceled out at the respective end openings of the intake duct and the exhaust duct, thereby reducing the noise.

According to a fourth aspect of the present invention, there is provided an air ejecting apparatus for separating a leading end of an object to be transported by blowing air, a vacuum feeding apparatus for feeding a document while sucking a document by an air suction force, and an air ejecting apparatus. In a feeding device comprising a first blower device connected to the device and a vacuum feeding device for supplying air and a second blower device for suctioning air, an intake duct connected to the first blower device,
An exhaust duct connected to the second blower device,
Each end opening of the intake duct and the exhaust duct is in the same plane, the openings of the end portions are arranged adjacent to each other and oriented in the same direction, and the rotation speed of the first blower device and the second blower device is stepless. When changing to, the frequency detecting means for generating a frequency according to the rotation speed, and according to the frequency generated by the frequency detecting means, the difference between the length of the intake duct and the length of the exhaust duct,
It is characterized by comprising control means for setting the wavelength of the main frequency generated by the first blower device and the second blower device to an odd multiple of half the wavelength of the main frequency.

According to the fourth aspect of the present invention, each end opening of the intake duct and the exhaust duct is on the same plane, and the end openings are disposed adjacent to each other and are oriented in the same direction. When the rotation speeds of the blower device and the second blower device vary steplessly, frequency detection means for generating a frequency according to the rotation speed, and the length of the intake duct according to the frequency generated by the frequency detection means. Control means for setting the difference in the length of the exhaust duct to an odd multiple of half the wavelength of the main frequency generated by the first blower device and the second blower device is provided.
By controlling the difference between the intake duct and the exhaust duct so as to be an odd multiple of half the wavelength of the main frequency generated by the blower device, the main frequency is always set to each of the intake duct and the exhaust duct. The noise cancels each other out at the end openings, so that the noise can be reduced.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an air separating and feeding mechanism of an automatic document feeder of the feeder of the present invention. In FIG. 1, there are two flows of air: a flow A of an air ejecting device 2 for separating the leading end of the original 1 and a flow B of a vacuum device 3 for feeding the original 1 while sucking the original. This feeding device has a general air injection device 2, a vacuum device 3, and a blower device (blower) 4.

The air injection device 2 includes a centrifugal fan 5 (contained in a fan casing 6) of a blower device 4, a nozzle casing 7, an air knife nozzle 8, and the like. The vacuum device 3 includes a rubber feeding belt 12 having a large number of air holes 11 driven by rollers 9 and 10, a vacuum tank 13 disposed inside the feeding belt 12,
It is formed from the centrifugal fan 14 of the blower device 4. In FIG. 1, the air seems to be circulating at first glance, but the air injection and the vacuum are separate systems and are not circulating.

As shown in FIG. 2, the centrifugal fan 5 of the blower device 4 on the side of the air injection device 2 that generates wind is fixed to one end of a motor shaft 16 of one blower motor 15 and the blower device of the vacuum device 3 side. The centrifugal fan 14 is fixed to the other end of the motor shaft 16 of the one blower motor 15.

The blower device 4 shown in FIG.
And a motor shaft 16 and two centrifugal fans 5, 14 for injection (for air supply) and vacuum (for air suction).
The blower motor 15 is fixed to a motor bracket 21 via a vibration-proof rubber 20 with a screw 22 to block vibration. The motor bracket 21 is fixed to an automatic document feeder (not shown) with screws 23. The two centrifugal fans 5, 14 are fixed to a motor shaft 16 protruding from both sides of the motor 15. The distal end of the motor shaft 16 is threaded, and the centrifugal fans 5, 14 are screwed with set screws 25 via spacers 24. The set screw 25 is shaped so that the flow of the wind is smooth.

FIGS. 3 and 4 show the centrifugal fans 5, 14 of FIG.
FIG. 3 is an external view of the centrifugal fans 5 and 14 as viewed from the direction A1 shown in FIG. A central shaft hole 26 is formed at the center of each of the centrifugal fans 5 and 14, and these central shaft holes 26 have a D-shape. The cross-sectional shape of the motor shafts 16, 16 of the motor 15 also has a D-shape, has a cut portion on the same plane, and matches the center shaft hole 26. Thereby, each centrifugal fan 5,
Numeral 14 is positioned and fixed in the rotational direction with respect to the motor shafts (drive shafts) 16.

Characteristically, the center shaft holes 26, 26 of the centrifugal fans 5, 14 are positioned one by one with respect to the circumferential arrangement of the blades 5a, 14a, as can be seen by comparing FIGS.
It is shifted by / 2 pitch. Therefore, as shown in FIG. 2, the two centrifugal fans 5, 14 are
When the blades 5a and 14a are mounted in the circumferential direction (rotational direction), the blades 5a and 14a are mounted at positions displaced from each other by a half pitch.

When the motor shaft 16 of the blower motor 15 rotates, when the centrifugal fans 5 and 14 begin to cut air,
The mounting angles of the centrifugal fans 5, 14 are the blades 5a, 14a.
Are shifted by ピ ッ チ pitch, the timing at which the centrifugal fans 5, 14 start to tear the air can be shifted accordingly. In other words, the blades 5a, 14a of the centrifugal fans 5, 14 shown in FIG. 2 and the air generate sinusoidal vibrations (sounds) that are shifted from each other by a half wavelength, and cancel each other out. In order to enhance this effect, it is desirable that the distance L between the centrifugal fans 5 and 14 is sufficiently smaller than the generated wavelength λ. However, in the present embodiment, the distance L is several tens mm because the size of the blower motor 15 is large. It is. The generated wavelength λ (m) can be expressed as follows when the number of blades is 12 at a motor rotation speed of 7000 rpm (rotation speed per minute).

[0034]

(Equation 1)

A hole is formed in a portion of the vacuum tank 13 shown in FIG. 1 which is covered with the feeding belt 12, and when the blower device 4 is operated, the lowermost one of the original 1 passes through the air hole 11 of the feeding belt 12. The sheet is sucked, and the feeding belt 12 is rotated by the rollers 9 and 10 in this state to convey one document 1. The feeding belt 12 is arranged so as to suck the center of the document 1 when the document 1 is set.

The shutter 17 of the vacuum device 3 of FIG.
The shutter opens and closes when the shutter solenoid is turned on and off, and controls the operation of the vacuum device 3. When the shutter solenoid shown in FIG. 1 is not operating, the shutter 17 is closed in a broken line state. When the shutter 17 is closed in a broken line state, the shutter 17 is not vacuumed. Vacuum when coming to.

7 and 8, the separation and feeding of the original 1 will be described. The document 1 is set on a feeding belt 12 of a vacuum tank 13 which is a part of a document table. At first, the shutter 17 of the vacuum device 3 is closed so as not to suck. When a start switch (not shown) is pressed, the blower motor 15 starts rotating, and the air injection device 2 starts working. Then, air is jetted from the air knife nozzle 8 toward the center of the end face of the document 1. As a result, air is blown between the originals 1,
Be judged. When the document 1 is sufficiently separated, the shutter 17 of the vacuum device 3 is opened by the operation of the solenoid 18, and the lowermost document 1 is attracted to the surface of the feeding belt 12.

Next, a paper feed motor (not shown) rotates,
The document 1 is conveyed to the sheet feed roller pair 19 by rotating the feed belt 12 in the white arrow direction. When the original 1 is conveyed to the paper feed roller pair 19 as shown in FIG.
Closes and stops suction. The feed motor also stops. If the original is sucked, the original 1 is fed while being forcibly peeled off from the feeding belt 12, thereby damaging the original 1. If the paper feed motor is also kept rotating, the originals 1 are fed one after another on their own, causing a jam. Therefore, the shutter solenoid 18 and the sheet feeding motor operate at a certain timing.

As described above, in the vacuum device 3, the wind is not exhausted from the centrifugal fan 14 when the original 1 is sucked and when the shutter 17 is closed. for that reason,
If the air is circulated by one centrifugal fan, the injection of air becomes unstable. Therefore, two centrifugal fans are used, and two systems of air flow are required. This is because the air injection needs to be always constant.

Next, another embodiment of the present invention will be described with reference to FIGS. FIG. 5 shows an air separating and feeding mechanism of the automatic document feeder of the feeder. The basic configuration is the same as that of the apparatus of FIG. The description will be omitted, and different portions of the embodiment shown in FIGS. 5 and 6 will be described below.

5 and 6, the air injection device 42
Differs from the air injection device of the device in FIG. 1 in that air is sucked through a duct 27. Further, in the vacuum device 43, in the device of FIG. 1, air is simply scattered around, but in the device of FIG. 5, a fan casing 46 is provided and the air is exhausted through the duct 28. The first blower device 47A is a fan casing 4
6 and the fan 5, and the second blower device 47 </ b> B has a fan casing 46 and the fan 5.

The end openings 29, 29 of the ducts 27, 28 are set on the same plane, and the end openings 29, 29 are adjacent and face the same direction. Nozzle casing 7, vacuum tank 13, fan casing 46 and duct 2
It is desirable that the materials 7 and 28 be made of a material having a large transmission loss, such as metal, so that noise does not leak to the outside. Here, the centrifugal fans 5 and 5 are attached.
Are also matched to the state shown in FIG. 4, and they are attached so that there is no deviation in the pitch of the blades. Ducts 27, 28
Is a flow path for air, but also functions as a noise propagation member. The noise propagation distance of the duct 27 is P1, and the noise propagation distance of the duct 28 is P2. These noise propagation distances P1, P
2 is provided with a path difference. In this embodiment, the noise propagation distance P1 <P2. Here, when the path difference between the noise propagation distances P1 and P2 is an odd multiple of half the wavelength λ / 2 of the wavelength λ of the sound having the highest noise level (main frequency), that is, the following equation is obtained with N as a natural number. Relational expression,

[0043]

(Equation 2)

When the above condition is satisfied, the sounds of the wavelength λ interfere with each other at the end openings 29, 29 which are the noise output ports at the ends of the ducts 27, 28 so as to cancel each other.

The noise frequency of the fan is not only the fundamental frequency, but also a higher harmonic of a natural number multiple of the fundamental frequency may have a higher noise level than the fundamental frequency. In this case, it is effective to adjust the path difference to the frequency having the highest noise level.

Next, still another embodiment of the present invention will be described with reference to FIGS. In the embodiment of FIGS. 9 and 10, illustration and description of the same parts as in the embodiment of FIG. 5 are omitted, and different parts are illustrated and described. FIG. 9 is a plan view of the ducts 27 and 58,
The structure of 8 is different from the conventional duct 28. Duct 5
8 has duct portions 58A, 58B, 58C, and has shutters 34 near both ends of the duct portions 58a, 58b.
A and 34B are arranged. These shutters 34
A and 34B can be opened and closed by fulcrums 36A and 36B.

As shown in FIG. 9, the shutters 34A, 3A
4B can be opened and closed by solenoids 35A and 35B, respectively, and the state indicated by the solid lines of the shutters 34A and 34B closes the duct portions 58A and 58B,
The state shown by the broken lines of A and 34B is the duct parts 58A and 58B.
Open B. As shown in FIG.
5B and the blower motor 15 are turned on by the control means 37,
Off control is possible. Document height detecting means 3 shown in FIG.
The potentiometer 32 of No. 3 includes a potentiometer 32, a fulcrum 30, and a detecting piece 31 as shown in FIG. 7, and the potentiometer 32 generates an analog signal proportional to the rotation angle of the detecting piece 31. The detection piece 31 rotates according to the amount of the original 1 loaded. The intensity of the wind blown to the document 1 is changed according to the document height detection result obtained from the document height detecting means 33. If the amount of original 1 is small and the same amount of air is blown as the maximum amount of original,
This is because a strong wind hits the leading end of the document 1 and the document 1 blows off or the set position is out of order. This changes the intensity of the wind by changing the rotation speed of the blower motor 15.

In this embodiment, the amount of originals
For example, the air volume can be changed in three stages. For example, when the analog data of the potentiometer 32 is output from zero to the maximum value and the analog data of any one of the three ranges is output, the rotation of the blower motor 15 is changed. The number is made to correspond to one of the three types of set rotation speeds. The frequency at which the blower motor 15 rotates at three types of rotation speeds is measured in advance, and the frequency with the highest noise level is confirmed.

Therefore, if the frequency of the blowers 47A, 47B changes in three stages, the wavelength λ of the frequency also changes, and accordingly, the end openings 29, which are the noise output ports at the ends of the ducts 27, 28, match. In order to cause the sounds having the wavelength λ to cancel each other at 29, three kinds of path differences between the ducts 27 and 28 are required.

For example, the number of rotations of the blower motor 15 is set to 3000 rpm, 5000 rpm, 7
000 rpm, and when the fundamental frequency of the fan has the highest noise level, the wavelength λ is determined by setting the number of blades to 1
Assuming two sheets, the number of rotations m (rpm: number of rotations per second),
The number of blades n, the sound speed v = 340 (m / s), and the fundamental frequency f (Hz) of the generated fan are:

[0051]

(Equation 3)

When the path difference between the ducts 27 and 28 is an odd multiple of a half wavelength of the wavelength λ: λ / 2, the sounds of the wavelength λ cancel each other out at the end openings 29 and 29 which are the noise output ports. Interfere with. Here, the half wavelength is used as a path difference, and at 7000 rpm, the duct portion 58A,
At 5000 rpm, the duct part 58B, 3000 rpm
In the case of m, when the duct portion 58C is used, the length of the path is set at the end openings 29, 29 so that the sounds of the wavelength λ interfere with each other so as to cancel each other. The path difference in the duct 58 is changed by opening and closing the shutters 34A and 34B. The shutter mechanism is the same as the shutter mechanism shown in FIG.

The control means 37 shown in FIG.
When current is applied to A and 35B, it is sucked and shutter 34
A and 34B are closed, and the shutter opens automatically when the current is turned off. The shutters 34A and 34B open and close around the fulcrums 36A and 36B at the timing of turning on and off the solenoid, and control the length of the duct 58. When the solenoid is not operated, the shutters 34A and 34B are closed in the state of the broken line.

The control means 37, as shown in FIG.
PU (Central Processing Unit) 37a, ROM 37b, RAM3
7c, an input / output circuit and an A / D converter 37d. The CPU 37a has various judgment and processing functions.
The OM 37b determines the number of rotations of the blower motor 15 according to a signal corresponding to the document stacking amount from the document height detecting means 33, and stores a program and fixed data necessary for controlling the solenoids 35A and 35B to be turned on and off. This is the stored program memory. The RAM 37c is a data memory for storing processing data. The A / D converter 37d is
The voltage from the potentiometer 32 of the document height detecting means 33 is converted into a digital value.

A signal corresponding to the document loading amount from the document height detecting means 33 is transmitted to the control means 37, and the control means 37 determines the number of rotations of the blower motor 15 and the shutters of the shutters 34A and 34B according to the signal. Determine the position.
That is, the control means 37 controls the rotational speed of the blower motor 15 to 70
If it is determined to be 00 rpm, the solenoid 35A is pulled to bring the shutter 34A to the position indicated by the broken line. Thus, the duct 58A is used. Blower motor 1
If the number of rotations of 5 is determined to be 5000 rpm, only the solenoid 35B is pulled to bring the shutter 34B to the position indicated by the broken line. In this case, the duct 58B is used. When the rotational speed of the blower motor 15 is determined to be 3000 rpm, the solenoid is not sucked and the duct 58C is used.

By doing so, the blower motor 15
Even when the number of rotations is changed stepwise, the generated frequency can be set to a length of a path that causes the sounds of the wavelength λ to interfere with each other so as to cancel each other at the end openings 29, 29 of the ducts 27, 58. it can.

Next, still another embodiment of the present invention will be described with reference to FIGS. 11 and 12
In this embodiment, illustration and description of portions similar to those in the embodiment of FIG. 5 are omitted, and different portions are shown and described. FIG. 11A shows a state where the path length of the duct 28D is the shortest, and FIG. 11B shows a state where the path length of the duct 28D is the longest. In the embodiment of FIG. 9, the number of rotations of the blower motor 15 is set to three stages. However, when the amount of air to be blown is changed steplessly in accordance with the document stacking amount,
The embodiment of FIG. 11 is effective.

The frequency detecting means 38 includes a blower 47
A, 47B blower motor 15 or centrifugal fans 5, 14
In order to detect the number of rotations, a detection signal is sent to the control means 39 by a pulse generator or the like to control how much the duct drive motor 42 should be driven to rotate.

The path length of one duct 27 is fixed, while the path length of the other duct 28D can be varied steplessly.
The precision rack 40 is cut into the side surface of the movable duct 28D, and the gear 41 meshes with the precision rack 40. The duct drive motor 42 drives the gear 41 to rotate. The projection 43 for the sensor projects from the duct 28D, and the duct sensor 44 detects the projection 43. The duct sensor 44 is formed of a transmission type photo interrupter, and is turned off when the sensor projection 43 enters the duct sensor 44. At this time, the length of the duct 28D is minimized and the duct 28D is set to the home position. When the power is turned on again, the duct 28D always returns to the home position once. The duct sensor 44 and the duct drive motor 42 are connected to the control means 39 and are automatically controlled.

The control means 39, as shown in FIG.
U (central processing unit) 39a, frequency detecting means 38, RO
M39b, RAM 39c, input / output circuit and driver 39d
Etc. The CPU 39a has various judgment and processing functions. The ROM 39b is a program memory that stores a program and fixed data necessary for controlling the rotation amount of the duct drive motor 42 according to a signal from the frequency detection unit 38. The RAM 39c is a data memory that stores processing data. The driver 39d drives the duct drive motor 42.

In FIG. 11 and FIG.
Receives a signal from the frequency detecting means 38. The control means 39 stores in advance in the ROM 39b, as a table, how many pulses of the duct drive motor 42 should be rotated to obtain the path difference between the ducts 27 and 28D, and the relation data between the rotation speed of the duct 28D and the blower motor 15 as a table. Let me. The control means 39 instructs the duct drive motor 42 to cause the generated frequency to interfere based on the stored relation data, and adjusts the path difference between the ducts 27 and 28D. By performing such control, the noise of the blower devices 47A and 47B can always be reduced.

Note that the present invention is not limited to the above embodiment, and various modifications are possible. For example, the cross-sectional shape of the duct may be circular or elliptical in addition to rectangular.

[0063]

According to the first aspect of the present invention, by utilizing the air injection device and the vacuum feeding device, the fan of the air blower and the fan of the vacuum blower are substantially 1/1 mutually.
Vibration (sound) of a sine wave shifted by two wavelengths is generated, and the noises cancel each other, whereby the noise can be reduced. Therefore, space saving and noise reduction can be achieved at low cost.

According to the second aspect of the present invention, by utilizing the duct of the air injection device and the duct of the vacuum feeding device, noise is canceled out at each end opening of the intake duct and the exhaust duct. Can be reduced. Therefore, space saving and noise reduction can be achieved at low cost.

According to the third aspect of the invention, by utilizing the duct of the air injection device and the duct of the vacuum feeding device, the rotation speed of the blower device is changed stepwise according to the number of documents.
When the amount of air blown is changed stepwise, even if the duct length is switched for each rotation speed of the blower device, the ends of the intake duct and exhaust duct cancel each other out of noise, which Noise can be reduced.

According to the fourth aspect of the present invention, the difference between the intake duct and the exhaust duct is controlled to be an odd multiple of half the wavelength of the main frequency generated by the blower device, so that the main duct is always controlled. At the end openings of the intake duct and the exhaust duct cancel each other out, thereby reducing the noise.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a motor and a centrifugal fan according to the embodiment of FIG. 1;

FIG. 3 is a diagram showing one of the centrifugal fans of FIG. 2;

FIG. 4 is a view showing the other centrifugal fan of FIG. 2;

FIG. 5 is a perspective view showing another embodiment of the present invention.

FIG. 6 is a plan view showing a setting example of the duct of FIG. 5;

FIG. 7 is a diagram illustrating a state in which air is jetted to a document.

FIG. 8 is a diagram illustrating a state in which a document separated by air in FIG. 7 is sent.

FIG. 9 is a diagram showing another embodiment of the present invention.

FIG. 10 is a block diagram illustrating an example of a control unit in FIG. 9;

FIG. 11 is a view showing still another embodiment of the present invention, showing a state where the path length of the duct is the shortest and a state where the path length of the duct is the longest.

FIG. 12 is a block diagram illustrating an example of a control unit in FIG. 11;

FIG. 13 shows a conventional document feeder (automatic document feeder).
FIG. 3 is a perspective view showing the air separation and feeding mechanism of FIG.

14 is a diagram showing a shutter of a vacuum device of the conventional document feeder of FIG.

FIG. 15 is a diagram illustrating a state in which air is jetted on a document in a conventional document feeder.

FIG. 16 is a diagram illustrating a state in which a document separated by air in the related art is sent.

FIG. 17 is a diagram showing a motor and a centrifugal fan of a conventional document feeder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Document (conveyed object) 2 Air injection device 3 Vacuum feeding device 4 Blower device (blower) 5 Air supply fan 14 Air suction fan 15 Motor 16 Motor drive shaft 47A First blower device 47B Second blower Apparatus 27 Intake duct 28 Exhaust duct 29 End opening 37, 39 Control means 38 Frequency detection means

Claims (4)

[Claims] 1. An air ejecting device for separating a leading end of a conveyed object by blowing air, a vacuum feeding device for feeding a document while adsorbing a document by an air suction force, and an air ejecting device and a vacuum feeding device. In a feeder comprising a blower for supplying air and sucking air, each of which is connected to a blade of an air supply fan of the blower and a blade of the air suction fan of the blower at both ends of a drive shaft of one motor. The same blade is used for the fan for air supply and the fan for air suction, and the mounting angle of the fan for air supply and the blade for air suction with respect to the drive shaft is A feeding device characterized in that it is shifted by substantially 1/2 pitch. 2. An air ejecting device for separating a leading end of a conveyed object by blowing air, a vacuum feeding device for feeding a document while adsorbing a document by an air suction force, and an air ejecting device and a vacuum feeding device. In a feeding device having a first blower device connected to supply air and a second blower device sucking air, the first blower device and the second blower device have the same structure and the same rotational speed. There is an intake duct connected to the first blower device, and an exhaust duct connected to the second blower device, and each end opening of the intake duct and the exhaust duct is on the same plane. The openings at the ends are adjacent to each other and face the same direction. The length of the intake duct and the length of the exhaust duct include the wavelength of the main frequency generated by the first blower device and the second blower device. Half-wave odd number A feeding device characterized in that a double difference is set. 3. An air ejecting device for separating a leading end of a conveyed object by blowing air, a vacuum feeding device for feeding a document while adsorbing a document by an air suction force, and an air ejecting device and a vacuum feeding device. In a feeding device having a first blower device connected to supply air and a second blower device sucking air, a feed duct connected to the first blower device and a feeder tube connected to the second blower device are provided. Exhaust duct, and each end opening of the intake duct and the exhaust duct are in the same plane, the end openings are arranged adjacent to each other, and are oriented in the same direction, and the first blower device and The rotation speed of the second blower device is stepwise variable, and the length of the intake duct and the length of the exhaust duct are changed by the variable number of rotation speeds of the first blower device and the second blower device. And the second blower device Raw is set to the difference of an odd multiple of the half wavelength of the main frequency, the first
A feed device comprising a control means for switching a duct length for each rotation speed of a blower device and a second blower device. 4. An air ejecting device for separating a leading end of a conveyed object by blowing air, a vacuum feeding device for feeding a document while sucking a document by an air suction force, and an air ejecting device and a vacuum feeding device. In a feeding device comprising a first blower device connected to supply air and a second blower device to suction air, an air intake duct connected to the first blower device, and a feeder device connected to the second blower device. Exhaust duct, and each end opening of the intake duct and the exhaust duct are in the same plane, the end openings are arranged adjacent to each other, and are oriented in the same direction, and the first blower device and Frequency detection means for generating a frequency in accordance with the rotation speed when the rotation speed of the second blower device varies steplessly; length of the intake duct and exhaust duct in accordance with the frequency generated by the frequency detection means Head of A feeding device comprising: a control unit for setting a difference in length to an odd multiple of a half wavelength of a wavelength of a main frequency generated by a first blower device and a second blower device.