JPH0950152A - Noise reduction mechanism for automatic document feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noise reduction mechanism for an automatic document feeder which resonates the frequencies of noises in the device, produced due to air blow and the like, by means of a resonator in the device, thereby muffling the sounds, and resonates peak frequencies at the same time or in order from a high level, thereby muffling the sounds. SOLUTION: The amount of air from an air injector 4 for separating a document 27 by injecting air onto the document 27 and the amount of air from a vacuum feeder 5 for sucking and carrying the separated document are adjusted according to the amount of loaded documents 27. Noises produced from the air is resonated by a resonator 1 having a resonance space 2 and resonance passage 3, which is provided in the automatic document feeder(ADF) 8, the shape of the resonator 1 is adjusted by an adjusting means so as to correspond to the frequencies, and, thus, air noise reduction is achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise reduction mechanism in general OA equipment provided with an automatic document feeder for producing air noise generated by blowing and sucking air.
In particular, the present invention relates to a noise reduction mechanism of an automatic document feeder that can automatically reduce noise in response to changes in the frequency of noise generated in the apparatus.

[0002]

2. Description of the Related Art OA equipment has various noise sources,
The noise reduction is demanded. In particular, there are many complaints from the market regarding the noise problem of the automatic document feeder, and even if the main body of the copying machine is low in noise, there is a problem that the image of the entire machine is deteriorated due to the noise from the automatic document feeder. Especially in the case of a high-speed machine, since the document replacement speed is high, the drive system rotates at high speed and the noise is large. Further, in the case of ultra high speed, the original is damaged in the friction separation, so that the method of separating the original with air is adopted and a high air noise is generated, so that the noise reduction is particularly required.

Various known techniques have been disclosed as a noise reduction mechanism for OA equipment. For example, JP-A-63-28
No. 6379, No. 4-469, No. 4-
No. 22659, No. 4-277762, No. 6-51228 and No. 6-20838.
No. 5 publication and the like are mentioned.

First, the "silencer" disclosed in Japanese Patent Laid-Open No. 63-286379 has a silencing chamber having a fixed slit and a resonance silencing chamber at a position facing a noise source in a case of the equipment. . The "laser printer device" of Japanese Patent Application Laid-Open No. 4-469 is a system in which a sound deadening port of a hollow cylindrical tube having an appropriate volume is connected to a soundproof cover which covers a gear part provided adjacent to the developing device unit. .

The "impact printer" of Japanese Patent Application Laid-Open No. 4-22659 has a paper separator having a plurality of cavities having different capacities, which is wide in the vicinity of the entrance and exit of the printing paper of the outer case which covers the printing part including the platen. It is designed to mute the band. The "document feeder" of Japanese Patent Laid-Open No. 4-277762 has a duct in which a sound absorbing material and a vibration damping material are attached to the air outlet.

The "optical deflector" of Japanese Patent Application Laid-Open No. 6-51228 discloses a resonance means in which a fixed resonance chamber is provided adjacent to the rotating space of a polygonal mirror so that the two can communicate with each other through a through hole. Is. Further, in Japanese Patent Laid-Open No. 6-208385, "Noise Absorbing Device for Copier", a main body of the noise absorbing device is arranged on the exterior of the main body of the copying machine, and the noise absorbing device adjusts the volume of the resonance box body to a noise frequency. It is formed so as to be variably and automatically controlled together.

[0007]

As mentioned above, the OA
There is a strong demand for noise reduction of equipment, and various known techniques as described above are adopted upon request. Although these known techniques have their respective characteristics, they are insufficient as noise reduction means for an automatic document feeder using air.

That is, the noise reduction means disclosed in JP-A-63-286379, JP-A-4-469, and JP-A-6-51228 are those in which the resonance chamber and the resonance passage are fixed. However, there is a problem that the silencing frequency is specified. The duct disclosed in Japanese Patent Laid-Open No. 4-277762 has a frequency of 800 to 1000 that can be absorbed by a sound absorbing material or the like.
There is a problem that the frequency band of [Hz] or higher is emitted outside without absorbing sound in the frequency band lower than that.

Since the paper separator disclosed in Japanese Patent Laid-Open No. 4-22659 has a plurality of cavities having different volumes, the frequency range of sound to be muted is wide, but those cavities are fixed and variable according to the purpose of use. It is not adjusted to. The noise absorbing device disclosed in Japanese Patent Laid-Open No. 6-208385 makes the volume of the resonance chamber variable in accordance with the frequency band, but does not variably adjust the shape of the resonance passage leading to the resonance chamber. Since it is not possible to muffle a plurality of frequencies almost at the same time, it is insufficient as a means for reducing noise in a high-speed automatic document feeder or the like.

The present invention solves the above-mentioned problems and makes it possible to change the shapes of the resonance space and the resonance passage in correspondence with various frequencies for reliable noise suppression, and to simultaneously generate noise at various frequencies or at the same time. It is an object of the present invention to provide a noise reduction mechanism for an automatic document feeder that can reduce noise in a descending order of high noise.

[0011]

A noise reduction mechanism of an automatic document feeder according to a first aspect of the present invention includes an air jetting device for blowing air to the leading end of stacked documents to separate the leading end. A vacuum feeding device for sucking the lowermost original document by air and supplying it to a predetermined conveying system, a blower device connected to both devices for blowing and sucking air, and engaged with the blower device. In the automatic document feeder including a control device, a resonance space of an appropriate volume that resonates with the frequency of sound generated when the blower device operates, the space, and the automatic document feeder side. It is characterized in that a resonance passage having an appropriate area for communicating with and is integrally formed.

According to a second aspect of the present invention, there is provided a noise reduction mechanism for an automatic document feeder, wherein the resonance space and / or the resonance passage has a volume of the resonance space and / or a cross-sectional area of the passage and / or a length of the passage. Adjusting means for adjusting the rotation speed of the blower device is automatically provided according to the detection signal of the stacking amount of the originals, and the control device corresponds to the rotation speed. It is characterized by having a control means for automatically controlling the adjusting means.

In the noise reduction mechanism of the automatic document feeder according to the present invention, the resonance space and the resonance passage are Helmholtz resonators, and the adjusting means adjusts the passage width of the resonance passage of the resonator. The control device automatically adjusts the passage width through the adjusting means on the basis of a fundamental frequency of the fan, which is determined by the number of rotations of the fan and the number of blades of the blower device. To do.

A noise reduction mechanism of an automatic document feeder according to a fourth aspect of the invention is characterized in that the resonance space and the resonance passage are at least two or more.

In the noise reduction mechanism of the automatic document feeder according to a fifth aspect of the present invention, the control device automatically adjusts the plurality of resonance spaces and the resonance passages so that the resonance spaces and the resonance paths resonate in order from the highest frequency level. Is characterized in that.

[0016]

In order to separate the stacked originals one by one, an air jetting device and a vacuum feeding device are used. However, if the air corresponding to the stacking amount of the originals is not supplied, the separation is not performed smoothly. Therefore, the fan rotation speed of the blower device is changed in order to adjust the amount of air supplied from the blower device according to the stacking amount of documents. This changes the fundamental frequency generated by the fan. Since the adjusting means is formed so as to variably adjust the resonance space and the resonance passage, the resonance space and the resonance passage corresponding to the fundamental frequency are automatically received by receiving the adjustment command corresponding to the fundamental frequency from the control device. Can be formed into Further, by arranging a plurality of resonance spaces and the like, it is possible to muffle various noises at the same time. It is also possible to mute the noise in order from the one with the highest noise.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an automatic document feeder to which this embodiment is applied (hereinafter referred to as an automatic document feeder: ADF).
2 is a perspective view showing the air flow thereof, FIG. 3 is a perspective view showing the detailed structure around the blower device, FIGS. 4 and 5 are drawings showing the general structure of the Helmholtz resonator, and FIG. FIG. 7 is a diagram showing the Helmholtz effect, FIG. 7 is a partial cross-sectional view showing the schematic structure of the document load detector of this embodiment, and FIG. 8 is an embodiment of the Helmholtz resonator having a plurality of resonance spaces and the accompanying drawings. 9 is a sectional view showing an embodiment of the adjusting means according to the present invention, FIG. 9 is a diagram showing a result of frequency analysis of noise, and FIG. 10 is a block diagram of a control circuit of the control device of the present invention shown in FIG.

As shown in FIG. 1, the noise reduction mechanism of this embodiment includes a resonator 1 having a resonance space 2 and a resonance passage 3,
The air injection device 4, the vacuum feeding device 5, the blower device 6, the control device 7 and the like are housed in the ADF 8.

The resonator 1 is shown in FIGS. 4 and 5 in this embodiment.
The Helmholtz resonator 1a shown in (1) is used, but is not limited thereto. The Helmholtz resonator has a cavity length L
It is composed of a cavity 2a composed of a resonance space 2 having a volume h of h, a cavity thickness T and a cavity width W, and a passage 3a of a resonance passage 3 having a passage length Lb, a passage thickness T and a passage width X. As shown in FIGS. 1 and 2, the cavity 2a, which is a closed space, has a passage 3a.
To communicate with the space inside the ADF 8.

The air injection device 4 comprises an air knife casing 9 and an air knife 10 for blowing out air as shown in FIGS. 1, 2 and 7, and the air knife 10 communicates with the blower device 6.

The vacuum feeding device 5 includes rollers 11 and 12.
The feeding belt 13 is driven by, and the air suction means 14 arranged inside the feeding belt 13. The supply belt 13 is formed with a through hole (not shown) communicating with the air suction means 14. Further, the air suction means 14 is the blower device 6
Communicate with the side.

As shown in FIGS. 1, 2 and 3, the blower device 6 comprises a blower device body 15, an air passage 16 attached to the blower device body 15, a solenoid valve 17 for opening and closing the air passage 16, and the like. As shown in FIG. 3, the blower device body 15 includes a blower motor 18, a sirocco fan 19, and
An air inlet 20, an air outlet 21, an air outlet 22 and the like are arranged.

In addition, an air inlet 23 for feeding air into the blower device main body 15 and an air suction port 2 are provided in the air passage 16.
4, and an air passage 25 between the air inlet 23 and the air suction port 24
And an opening / closing lid 26 which is provided between them and which is opened / closed by a solenoid valve 17. The air suction port communicates with the atmosphere side through a filter (not shown) or the like, and the air ejection port 21 communicates with the air knife 10 as shown in FIG.

The air suction port 24 of the air passage 16 communicates with the air suction means 14 as shown in FIG. By opening the solenoid valve 17 and driving the blower motor 18 of the blower device main body 15, air is sucked inward from the air suction port 20 and the air suction port 24 and sent to the air knife 10 from the air blowing port 21. Further, the air in the air suction means 14 is sucked into a vacuum state, and a vacuum suction force acts on the feeding belt 13 side.

The ADF 8 has a document tray 28 on which the documents 27 are stacked, and the front end side of the document tray 28 is the feeding belt 13
Is extended to the vicinity of and is arranged at the same height position. The front end of the document 27 on the document tray 28 is arranged near the air knife 10 of the air ejecting device 4. The air knife 10 is arranged so as to face the lowest document 27 of the documents 27. On the lower side thereof, the feeding belt 13 is arranged closely. The air blown out from the air knife 10 forms an air layer between the lowest document 27 and the document above it, and the lowest document 27 is separated.

Further, the separated lowermost original is attracted to the feeding belt 13 side to be surely separated and mounted on the feeding belt 13 and conveyed. A transport roller 29 is arranged near the feeding belt 13. The original 27 is conveyed through various predetermined conveying paths and conveying rollers in the ADF 8,
The paper is discharged from the document discharge port 30.

Next, the silencing action of the Helmholtz resonator 1a will be described. First, assuming that the number of blades of the sirocco fan 19 is n and the number of rotations of the sirocco fan 19 by the blower motor 18 is N (rps), the fundamental frequency f of the wind noise generated during fan rotation is f = N · n (Hz). Become. Therefore, the frequency of the air delivered or sucked into the ADF 8 by the blower device 6 is f and an integral multiple thereof.

The Helmholtz resonator 1a has a function of introducing air in the ADF 8 into the chamber and causing the frequency of the air to resonate to muffle the sound. The Helmholtz resonance frequency Fh by the Helmholtz resonator 1a shown in FIGS. 4 and 5 is theoretically obtained by the following equation.

Fh = C / 2π (S / V · Lb) ^1/2 = C / 2π (X / Lb · Ln · W) ^1/2

In the above equation, C is the speed of sound, S is the cross-sectional area of the passage 3a = X.T, and V is the volume of the cavity 2a = W.Lh.T. From the above, X, Lb, Lh, which satisfy f = Fh,
By determining W, the noise in the ADF 8 can be reduced.

As an example, a concrete example of obtaining the passage width X with Lh, W and T being constant will be described below. The fan speed N of the sirocco fan 19 is set to 46.7 rps (2800 rp).
m) and the number of blades n is 16, f≈747 (H
z). Passage length Lb = 5 [mm], cavity width W = 5
0 [mm], cavity length Lh = 42 [mm], Fh =
When f = 46.7 [Hz], X≈2 [mm].
As described above, by appropriately determining the cavity thickness T, the Helmholtz resonator 1a that can be housed in the ADF 8 can be formed. If it cannot be stored, it may be attached to the outside of the ADF 8.

FIG. 6 shows the Helmholtz effect by the Helmholtz resonator 1a, in which the horizontal axis represents the frequency (Hz) and the vertical axis represents the noise reduction amount (dB). From the diagram, it can be seen that there is a noise reduction effect on the Helmholtz resonance frequency and the frequencies around it.

Next, referring to FIG. 7, the height detector 3 of the original 27 is detected.
1 will be described. As described above, if the same amount of air as that of the maximum load amount is blown and supplied when the load amount of the document 27 is small, a strong wind blows on the edge of the document 27 and the document flaps, which causes a jam at the time of feeding. May occur or the set position may become unstable. Therefore, it is necessary to adjust the air supply amount according to the stacking amount of the documents 27. The height detector 31 detects the stacking amount of the documents 27 mounted on the document tray 28 and inputs the detection signal to the control device 7.

As shown in FIG. 7, the height detector 31 has a detection piece 33 whose base end is pivotally supported by a fulcrum 32 fixed to the air knife casing 9 and a rotation angle of the detection piece 33. A potentiometer (not shown) that outputs an analog signal and a moving mechanism (not shown) including a rack, a pinion, a motor, and the like that reciprocates the fulcrum portion 32 in the direction of the arrow B in FIG. By moving the detection piece 33 according to the original 27, the detection piece 33 rotates in accordance with the stacking amount of the original 27 as shown by the chain line in FIG. Further, the detection piece 33 rotates downward due to the document 27 gradually decreasing.
As described above, the analog signal corresponding to the stacking amount of the original 27 is input to the control device 7 side each time.

FIG. 8 shows an embodiment of the adjusting means 34 of the present invention. The adjusting means 34 is for adjusting the passage width of the Helmholtz resonator 1a, and is composed of two sets of Helmholtz resonators 1a, 1a integrally connected. Of course, the adjusting means 34 is not limited to the present embodiment, and a structure having a structure capable of adjusting each component of the resonance space 2 and the resonance passage 3 is applied.

The adjusting means 34 adjusts the gap width X for adjusting the passage width X of the resonator main body 35 forming the cavities 2a, 2a and the passage 3a which goes in and out of the respective cavities 2a, 2a and communicates with the cavities 2a, 2a. It comprises a plate 36, a precision rack 37 carved in the protruding end of the gap adjusting plate 36, a precision gear 38 meshing with the precision rack 37, an adjustment plate drive motor 39 for rotationally driving the precision gear 38, and the like.

Further, there are provided a sensor protrusion 40 fixed to the gap adjusting plate 36, an adjusting plate sensor 41 and the like installed on the stationary side so as to be engaged with the protrusion 40. The adjusting plate sensor 41 is made of a transmissive photointerrupter, and is turned off when the sensor projection 40 is engaged with the adjusting plate sensor 41, and the passage width X becomes zero and the home position is set. The adjusting plate sensor 41 and the adjusting plate drive motor 39 are connected to the control device 7 and are automatically controlled.

Next, the structure of the control device 7 and its control operation will be described. The control device 7 automatically controls the blower device 6, the adjusting means 34 and the like. As shown in the block diagram of the control circuit of FIG.
2, a microphone amplifier 43, a frequency resolving means 44, a control means 45, the adjusting plate sensor 41, the adjusting plate drive motor 39 and the like.

The control means 45 is composed of a blower and a resonator control means, which controls the central processing unit (CPU) having various judgment and processing functions and the stacking height of the manuscript 27 inputted from the height detector 31. RO is a program memory that stores a program and fixed data necessary for controlling the rotation speed of the blower motor 18 of the blower device 6 according to the corresponding signal S _H and controlling the movement amount of the passage width X of the resonator.
M and a RAM that is a data memory that stores processed data
And an input / output circuit (I / O) and an A for converting the voltage from the potentiometer of the height detector 31 into a digital value.
/ D converter, blower motor 18 and resonator 1a passage width X
The microcomputer is composed of a driver or the like for driving the adjusting plate drive motor 39 for changing.

A signal S _H corresponding to the stacking height of the originals 27 is inputted from the height detector 31, and a rotation speed control signal S _B for the blower motor 18 and an adjusting plate drive motor 39 for changing the passage width X of the resonator 1a. The rotation amount control signal S _B is output. The blower and resonator control means increases the rotation speed of the blower motor 18 as the stacking height of the originals 27 increases.
In addition, the number of rotations of the adjusting plate drive motor 39 causes the passage width X
The relationship between the passage width X and the resonance frequency is stored in advance in the ROM as a table, and the rotation speed of the blower motor 18 is controlled to an optimum value based on the data to cause the generated frequency to resonate. The adjusting plate drive motor 39 that adjusts the passage width X is moved so as to attenuate it.

The blower and resonator control means is a central processing unit (CPU) having various judgment and processing functions.
And ROM, which is a program memory that stores programs and fixed data required for detection in order of increasing level in frequency analysis data, RAM that is a data memo that stores processed data, and input / output circuit (I / O)
And a microcomputer including an A / D converter for converting the voltage of the frequency level into a digital value and a driver for driving the adjusting plate drive motor 39 for changing the passage width X of the resonator 1a.

From the top, the CPU with the highest noise level is 2
Select one, and input the signal S _H corresponding to that frequency,
The rotation amount control signal S _B of the adjusting plate drive motor 39 that changes the passage width X of the resonator 1a is output. This is effective because it is possible to attenuate the sound from noisy ones generated in the ADF 8 not only by the preset specific frequency but also by the kind of the sound source. FIG. 9 shows an example of frequency analysis, and there are some frequency peaks as shown. In this case, even if one peak is lowered, it is not effective because there is noise of other peaks, and it is necessary to lower all peak frequencies. By the control method described above, noise can be effectively reduced even when many peak frequencies exist.

Since the ADF 8 of the present embodiment is a document circulation type, after the fed document 27 is copied, it is placed on the document tray 28 by the discharge rollers 46 (FIG. 1) in the same manner as in the initial set state. Is discharged. The ADF 8 circulates the original 27, but when the original is first set on the original tray 28, the detection piece 33 of the height detector 31 is set as shown by the chain line in FIG. 7 before the first sheet is fed. After retreating to the left, the upper end of the original 27 again projects upward with the right end rotated upward, and then the contact state is maintained by its own weight until the copying operation is completed. Therefore, the boundary between the original 27 set on the original tray and the original that has been circulated and returned is clear.

The number of revolutions of the blower motor 18 can be changed stepwise in accordance with the height of the original 27, or can be changed steplessly. Resonator 1a
The passage width X of is also changed accordingly to resonate the sound.

In this embodiment, the adjustment of the passage width X is automatically decided by S _H , but the blower motor 1
The control may be such that the rotation speed of 8 is detected by a pulse encoder or the like and the passage width X is calculated according to the actual rotation speed.

[0046]

According to the present invention, the following remarkable effects are obtained. 1) By incorporating a resonator having a resonance space and a resonance passage communicating with the resonance space inside the automatic document feeder and forming the resonator in a shape that resonates with the frequency of the noise, noise can be surely silenced. 2) Since the resonator can be formed in a shape corresponding to various frequencies by the adjusting means and the control device for automatically controlling the adjusting means, noise having various peak frequencies can be effectively silenced. 3) By adopting a Helmholtz resonator as the resonator, the resonator can be made compact, and can be housed in the ADF, and the resonance frequency of the resonator can be accurately obtained, so that the sound is surely silenced. 4) By disposing a plurality of resonators, noise having a plurality of peak frequencies can be silenced at the same time. 5) Effective noise reduction can be achieved by providing a plurality of resonators and muffling sound with a high frequency level.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a schematic structure of an ADF to which an embodiment of the present invention is applied.

FIG. 2 is a perspective view around a blower device for explaining the air blow in FIG.

FIG. 3 is a perspective view showing a detailed structure around a blower device.

4 is a cross-sectional view of the Helmholtz resonator taken along the line AA of FIG.

5 is a bottom view of FIG. 4 showing the external structure of the Helmholtz resonator.

FIG. 6 is a diagram showing the Helmholtz effect.

FIG. 7 is a partial cross-sectional view showing a schematic structure of a document stacking amount detector of the present embodiment.

FIG. 8 is a cross-sectional view showing an embodiment of a Helmholtz resonator having a plurality of resonance spaces and its adjusting means.

FIG. 9 is a diagram showing frequency characteristics of noise.

FIG. 10 is a block diagram of a control circuit of the control device of the present invention.

[Explanation of symbols]

 1 Resonator 1a Helmholtz Resonator 2 Resonance Space 2a Cavity 3 Resonance Passage 3a Passage 4 Air Injector 5 Vacuum Feeder 6 Blower Device 7 Controller 8 Automatic Document Feeder (ADF) 9 Air Knife Casing 10 Air Knife 11 Roller 12 Roller 13 Feeding Belt 14 Air Suction Means 15 Blower Device Main Body 16 Air Passage 17 Solenoid Valve 18 Blower Motor 19 Sirocco Fan 20 Air Suction Port 21 Air Blowout Port 22 Air Exhaust Port 23 Air Suction Port 24 Air Suction Port 25 Air Duct 26 Open / Close Lid 27 Original 28 Document Tray 29 Conveying Roller 30 Document Ejecting Port 31 Height Detector 32 Support Point 33 Detection Piece 34 Adjusting Means 35 Resonator Main Body 36 Gap Adjusting Plate 37 Precision Rack 38 Precision Gear 39 Adjusting Plate Drive Motor 40 Protrusion 41 Adjusting Plate Sensor 4 2 sensor microphone 43 microphone amplifier 44 frequency unfolding means 45 control means 46 paper ejection roller

Claims (5)

[Claims] 1. An air ejecting device for blowing and supplying air to the front ends of stacked documents to separate the ends thereof, and an air suction device for sucking the separated lowermost document by air and supplying it to a predetermined conveying system. In an automatic document feeder including a vacuum feeding device, a blower device connected to the both devices for blowing and sucking air, and a control device engaging with the blower device, inside the automatic document feeder, A manuscript characterized by integrally forming a resonance space of an appropriate volume that resonates with the frequency of sound generated when the blower device operates and a resonance passage of an appropriate area that connects the space and the automatic document feeder side. Noise reduction mechanism of automatic feeder. 2. The resonance space and / or the resonance passage is provided with adjusting means for adjusting the volume of the resonance space and / or the cross-sectional area of the passage and / or the length of the passage, and the control device It has a control means for automatically controlling the number of revolutions of the blower device in response to a detection signal of the stacked amount of the originals, and a control means for automatically controlling the adjusting means according to the number of revolutions. A noise reduction mechanism of the automatic document feeder according to Item 1. 3. The resonance space and the resonance passage are formed by Helmholtz resonators, the adjusting means is formed by adjusting a passage width of the resonance passage of the resonator, and the controller is a fan of the blower device. 3. The passage width is automatically adjusted through the adjusting means based on the fundamental frequency of the fan determined by the number of rotations and the number of blades.
Noise reduction mechanism of the automatic document feeder described in. 4. A noise reduction mechanism for an automatic document feeder according to claim 1, wherein the resonance space and the resonance passage are at least two or more. 5. The low noise of the automatic document feeder according to claim 4, wherein the control device automatically adjusts a plurality of resonance spaces and resonance passages to have a shape in which resonance frequencies are sequentially resonated in descending order of frequency level. Mechanism.