JP4176592B2 - Method for measuring vibration of separation pad in sheet feeding device, method for designing sheet feeding device, and sheet feeding device - Google Patents

Description

  The present invention relates to a method for measuring vibration of a separation pad that causes abnormal noise (squeaking) when a sheet is passed through a paper feeding device, a method for designing a paper feeding device based on the vibration frequency of the separation pad obtained by the method, and the design The present invention relates to a sheet feeding device designed by the method, and particularly to reduce noise generated when a sheet is passed in the sheet feeding device.

As shown in FIG. 1, the sheet feeder attaches a separation pad 1 serving as a friction member to the upper surface of a support base 2, and urges the support base 2 with a spring 3 to press the separation pad 1 against a paper feed roller 4. I am letting. When the sheet is passed, the uppermost sheet S1 stocked in the sheet cassette 5 is fed out by the sheet feeding roller 4, and the separation pad 1 is pressed against the lower surface of the next sheet, whereby the next sheet is fed by the frictional resistance of the separation pad 1. To prevent double feed.
In an image forming apparatus including a printer, a facsimile machine, a copier, and a multifunction machine including the above-described paper feeding device, an unpleasant noise called a cue / cue / shoe / shoe noise may occur when a sheet is passed. Many.

  The occurrence of squeal when passing paper is caused when the separation pad rubs against the paper and when the friction coefficient of the separation pad is large or when the separation pressure is high, the pad vibrates, and this vibration causes the pad support 2, the spring 3, and the paper cassette. No. 4 and the paper feeding device resonate and resonate, and noise is generated. In particular, in a color printer, if the sheet passing speed is decreased to increase color image accuracy, the vibration of the separation pad increases and the squeal tends to increase.

Various means for reducing and preventing the occurrence of the squeal have been provided.
In general, reducing the friction coefficient and increasing the hardness of the separation pad is an effective measure to reduce squeal, but if the friction coefficient is reduced and the hardness is increased, the multi-feed prevention performance is reduced and the squeal is reduced. It has been difficult to achieve both reduction in feed rate and prevention of double feed.
Therefore, the separation pad itself is created from the viewpoint of preventing double feed, and the method of absorbing the vibration of the separation pad with a member connected to the separation pad is adopted to reduce the noise.

For example, in JP-A-5-162877, the separation pad support is made of a high specific gravity resin composition containing metal powder, and the vibration of the separation pad is absorbed by the support to prevent resonance and resonance with other members. To reduce noise.
In Japanese Patent Laid-Open No. 5-178512, the support base of the separation pad is formed of a resin polymer having an internal loss of 0.03 or more, and vibration generated in the separation pad is absorbed inside the support base.
In Japanese Patent Application Laid-Open No. 2003-137448, a support base is formed of a rubber body, and heating means for heating the rubber body to such an extent that no abnormal noise is generated is provided.

However, even if the support base is made heavy or formed of a resin having vibration absorption properties, vibrations cannot be sufficiently absorbed for the high cost. Further, when the rubber body heating means is provided, there is a problem that the number of parts is increased and the number of assembling steps is increased because a heater and a temperature sensor are required.
As described above, various methods for reducing squeal at the time of paper passing in a paper feeder have been provided, but no effective means for reducing squeal without increasing the cost has been provided yet. This can be attributed to the fact that the sound that is to be reduced has not been scientifically investigated by relying on hearing, so that it is not possible to accurately grasp the material that is difficult to sound.
JP-A-5-162877 Japanese Patent Laid-Open No. 5-178512 JP 2003-137448 A

  The present invention has been made in view of the above-described problems, and scientifically analyzes the relationship between squealing and vibration of the separation pad, and based on it, it is possible to accurately select and set a material that is difficult to squeal, An object of the present invention is to provide a paper feeding device with reduced noise.

In order to solve the above-mentioned problems, the present invention first provides a measurement method capable of scientifically and simply analyzing vibrations with a separation pad which is considered to be a cause of squealing.
That is, the first aspect of the present invention is a paper feeding device that includes a paper feeding roller that transports paper and a separation pad that is pressed against the paper feeding roller, and passes between the paper feeding roller and the separation pad. , A method for measuring vibration of the separation pad, which causes abnormal noise that occurs when paper is passed,
Set a microphone near the paper feeder,
While recording the abnormal sound generated during the passage of paper with the microphone, the recorded abnormal sound is analyzed with a frequency analyzer to obtain the vibration frequency of the abnormal sound,
A pickup meter is attached to the transmission material that is fixed to the separation pad and pulled out, and the vibration of the separation pad during paper feeding is measured with the pickup meter through the transmission material, and the measured vibration is analyzed with a frequency analyzer. After obtaining the vibration frequency of the separation pad,
Compare the vibration frequency of the separation pad and the vibration frequency of the abnormal noise to derive a correlation,
Thereafter, a separation pad vibration measuring method for a sheet feeding device is provided in which the vibration frequency of abnormal noise is measured and the vibration frequency of the separation pad is obtained based on the correlation.

Conventionally, as described above, the noise reduction measures in the paper feeder are not scientifically analyzed as described above. Therefore, the separation pad, the pad support and each member are formed of a material that does not easily generate noise. The empirical measures to pass the paper through the paper feeder and listen to the squeal that occurs are all over. It is generally accepted that the noise during the passage of paper is due to the vibration of the separation pad, but since the separation pad is attached to the paper cassette and the paper passes through the upper surface of the separation pad, It is recognized that it is practically impossible to measure the vibration of the separation pad itself when the paper is passed. As a result, there has been no scientific analysis of abnormal noise caused by vibration of the separation pad.
The inventor conducted research and experiments on a method that can easily analyze the vibration of the separation pad, and as a result, found the measurement method described above.

That is, according to the first aspect of the present invention, the vibration frequency of the separation pad can be obtained from the abnormal sound that can be easily measured. Therefore, as described above, the frequency of the abnormal sound, the vibration frequency of the separation pad, and Thus, by introducing this correlation, the vibration frequency of the separation pad can be obtained without directly measuring the vibration of the separation pad.
As described above, the measurement of the vibration frequency of the separation pad, which is performed to obtain the correlation between the vibration frequency of the separation pad and the frequency of the abnormal sound, is performed by fixing one end of a transmission material such as a screw to the separation pad 10. The tip of the transmission material is pulled out to the outside, a pickup meter is attached to the transmission material drawn out to the outside, and the vibration of the separation pad during paper passing is measured with the pickup meter via the transmission material, and the measured vibration Was analyzed with a frequency analyzer to obtain the vibration frequency of the separation pad. While measuring the vibration of this separation pad is very laborious, it is easy to record the abnormal sound with a microphone and obtain the frequency of the abnormal sound from the recording, so the vibration frequency of the separation pad should be obtained from the frequency of the abnormal sound. In this case, the vibration of the separation pad that causes abnormal noise can be scientifically analyzed, which is very useful for speeding up the development and design of a paper feeding device that reduces abnormal noise.

  In addition, since the vibration frequency of the separation pad can be easily obtained from the vibration frequency obtained by recording an abnormal sound, how the separation pad works against changes in the load applied to the separation pad and the paper passing speed. It is possible to easily analyze the behavior that takes place. In general, the higher the friction coefficient of the separation pad, the higher the load applied to the separation pad, and the slower the paper passing speed, the more likely it is to squeal. For each load, it is possible to easily find out how much squealing is likely to occur at what load and sheet passing speed, and by selecting an appropriate friction coefficient, it is possible to maintain a balance between squealing and prevention of double feed.

According to the inventor's experiment, the measured vibration frequency of the abnormal sound and the vibration frequency of the separation pad were equivalent as shown in FIGS.
FIG. 2A shows the vibration frequency of an abnormal sound recorded by the microphone, and FIG. 2B shows the vibration frequency of the separation pad.
In the measured paper feeder, a high-pitched squeal occurred, and the frequency of the squeal reached 60 dB. The vibration frequency of the abnormal sound obtained by recording the abnormal sound at the time of passing the paper reached a peak at 330 Hz, and the vibration frequency of the separation pad itself reached a peak at 330 Hz.
Thus, when the vibration of the separation pad itself is measured, the present inventor has found that the vibration frequency of the separation pad is very close to and substantially equivalent to the vibration frequency of abnormal noise, and based on that, as described above, The vibration frequency of the separation pad is assumed to be the same as the vibration frequency of abnormal noise, and is applied to the design described later.

Secondly, the present invention is a method of designing a paper feeding device that reduces noise (abnormal noise) based on being equivalent to the vibration frequency of the separation pad obtained by the measurement method,
The separation pad including a support base for supporting the separation pad, a separation pad biasing spring, a paper cassette, a support shaft of the paper feed roller, a bearing member of the support shaft, and a housing material (for example, a printer body) of the paper feed device Designed to deviate between the natural vibration frequency of the members constituting the paper feeding device and the measured vibration frequency of the separation pad, and prevents resonance and resonance between the separation pad and the member, thereby preventing A design method for a paper feeding device that can reduce the occurrence of squealing is provided.

Due to the fact that the vibration frequency of the abnormal noise and the vibration frequency of the separation pad are the same, the occurrence of squeak when passing paper is caused by the vibration of the separation pad, and members other than the separation pad vibrate at the same frequency. From this, it was found that this phenomenon was caused by resonance and resonance.
Based on the above knowledge, a method for designing a paper feeding device with reduced squeal is provided. By separating the vibration frequency of the separation pad from the persistence vibration frequency of members other than the separation pad, the separation pad and the separation pad are separated. Resonance with members other than the pad and the occurrence of resonance based thereon can be prevented, and as a result, the occurrence of squeal due to the vibration of the separation pad can be reduced.

As members constituting the sheet feeding device other than the separation pad, the above-described support for supporting the separation pad, separation pad biasing spring, sheet cassette, shaft of the sheet feeding roller, bearing member of the shaft, sheet feeding For example, the housing material of the apparatus.
Although it is preferable to shift the natural vibration frequency of all members other than the separation pad described above from the vibration frequency of the separation pad, it is preferable that a vibration-prone member, for example, the support shaft of the paper feed roller or the separation pad biasing spring. It is possible to effectively reduce the squeal that occurs only by making the vibration frequency different from the vibration frequency of the separation pad.

  Specifically, the separation pad support, which is a member other than the separation pad, the spring for biasing the separation pad, the shaft of the paper feed roller, the bearing member, the paper cassette, the shape of the housing material, the material, the weight, or the above separation By changing the spring pressure of the pad biasing spring, these natural vibration frequencies are shifted from the vibration frequency of the separation pad.

In order to shift the vibration frequency of the separation pad from the natural vibration frequency, the vibration frequency of the separation pad itself is changed to the material, the friction coefficient, the weight, the shape, and / or the separation instead of the method of changing the member other than the separation pad. The type of resin of the pad may be changed.
In this case, since it is not necessary to measure the natural vibration frequency of the other member, the vibration frequency of the separation pad can be easily shifted from the natural vibration frequency of the other member.
At that time, by attaching a separation pad with a changed coefficient of friction, recording the squeal at the time of passing the paper and measuring the vibration frequency of the separation pad, the vibration frequency of the separation pad with the changed coefficient of friction is changed to another member. It is possible to easily verify whether or not the natural vibration frequency has deviated.

Thirdly, the present invention provides a paper feeding device configured based on the above design method.
In this paper feeding device, the vibration frequency of the separation pad is shifted from the natural vibration frequency of components other than the separation pad such as the support shaft of the paper feed roller and the separation pad biasing spring. Even if it vibrates, it can reduce that resonance and resonance with other members generate noise.

As described above, according to the present invention, it is possible to easily determine the vibration of the separation pad, which is the main cause of the occurrence of abnormal noise, based on the vibration frequency of abnormal noise that is easy to measure.
In addition, since the vibration frequency of the separation pad can be easily obtained in this way, it is possible to obtain a paper feeding device that reduces noise by designing so that other members do not resonate with the vibration of the separation pad. .

  In the embodiment of the present invention, as shown in the graph of FIG. 3 (A), the sheet feeding device that has generated low-temperature (boom) noise in the half-speed mode is replaced with the separation pad that is mounted on the sheet feeding device. The change is made to reduce the noise of the paper feeding device.

In FIG. 3A, when the paper is fed in the half speed mode which is half the normal paper feed speed, the sound pressure level reaches 50 dB at the peak near the frequency of 120 Hz, and a large noise is generated.
FIG. 3B shows a normal mode in which the paper is fed at a normal paper feed speed. The sound pressure level of abnormal noise was -10 dB even at the peak of the frequency near 120 Hz, and no squeal occurred.

The separation pad before the change showing the measured values in FIGS. 3A and 3B was formed from EPDM, and the specific gravity was 0.9.
As the separation pad after the change, the same resin was used, a tongue point was blended in the resin, and the specific gravity was set to 1.3 to obtain a separation pad having a high specific gravity.
In the sheet feeding device equipped with the separation pad, no abnormal noise was generated in the vicinity of 120 Hz as shown in the graph of FIG.

The relationship between the sound pressure level of abnormal noise and the vibration frequency in the graphs shown in FIGS. 3A, 3B, and 3C is based on the following measurement method.
As shown in FIG. 4, a printer 10 of company A with a paper feeder installed in an anechoic greenhouse is installed, and a microphone 11 (type 4165 manufactured by Bruel Care Co.) is placed near the printer 10. Abnormal noise generated when the paper was passed through the printer 10 at a conveyance speed of 40 mm / S was recorded. The microphone 11 has a microphone preamplifier (Model 2669B manufactured by Bruel Care Co.) 13 attached thereto, and the cable of the microphone preamplifier was directly connected to the frequency analyzer (Portable PULSE System 3560C manufactured by Bruel Care Co.). The frequency analyzer 12 includes a personal computer and a main body, and vibration analysis software (7700B type acoustic vibration analysis software 2669B type manufactured by Bruel Care Co.) is installed in the personal computer.
The graphs printed out from the frequency analyzer are shown in FIGS. 4A, 4B, and 4C.

Regarding the vibration frequency of the separation pad itself, the vibration frequency at the time of passing the paper in the half speed mode was measured before and after the change. The result is as shown in the graph of FIG. 5A before the change, and reaches a peak near 120 Hz, which is the same as the abnormal vibration frequency of FIG. 3A, and the vibration frequency of the separation pad is the abnormal vibration frequency. And the peaks were confirmed to be the same.
After the change, as shown in the graph of FIG. 5B, no peak occurred in the vicinity of 120 Hz, and it was confirmed that the vibration frequency of the separation pad itself was different from that before the change.

  As shown in FIG. 6, the vibration frequency of the separation pad itself is measured by fixing one end of a screw 15 to the separation pad 1 and projecting the other end of the screw 15 to the outside of the sheet feeding device. An acceleration pickup meter 16 was attached to the other end of the sensor. The accelerometer 16 was connected to a frequency analyzer 17 (dynamic single analyzer HP3562A, manufactured by Hewlett-Packard Company) via an amplifier, and the vibration frequency of the separation pad 1 was measured when the paper was passed. The graphs printed out from the frequency analysis device 17 are the graphs shown in FIGS.

Further, the natural vibration frequency of the support shaft of the paper feed roller, which is a component of the paper feed device other than the separation pad, and the printer body was measured. As a result, the natural vibration frequency of the spindle of the paper feed roller was as shown in FIG. 7A, and the natural vibration frequency of the printer body was as shown in FIG. 7B.
That is, the natural vibration frequency of the support shaft of the paper feed roller reached a peak at 100 to 130 Hz, reached a peak near 120 Hz, and coincided with the peak of the vibration frequency before the separation pad was changed. As a result, it was confirmed that the vibration of the separation pad resonated with the vibration of the support shaft of the paper feed roller and the vibration of the printer body, and abnormal noise was generated around 120 Hz as shown in FIG.

  Therefore, as shown in FIG. 5B, if the vibration frequency of the separation pad is made different so as not to reach the peak at 120 Hz, the natural vibration frequency of the spindle of the paper feed roller shown in FIG. 7 and a natural vibration frequency of the printer body shown in FIG. 7B. As a result, other members are caused by the vibration of the separation pad. It was confirmed that the squeaking during paper feeding was reduced. It was also confirmed that the vibration of the separation pad itself was reduced.

As described above, in this embodiment, the specific gravity of the separation pad is changed, and the vibration frequency of the separation pad is shifted from the natural vibration frequency of the support shaft of the paper feed roller and the printer body, which are other members. The squeal at the time is reduced.
However, the present invention is not limited to the above-described embodiment, the separation pad is not changed, and the material vibration frequency is separated by changing the material, weight, size, etc. of the support shaft of the paper feed roller and / or the printer body. Needless to say, by shifting the vibration frequency of the pad, it is possible to reduce the squeal when passing the paper.

It is a principal part schematic sectional drawing of a paper feeder. (A) is a graph showing the vibration frequency of the squeal, and (B) is a graph showing the vibration frequency of the separation pad. 1A and 1B are graphs showing the vibration frequency of a squeal before the change of the separation pad in the half-speed mode and the normal mode, and FIG. 3C is the vibration frequency of the squeal after the change of the separation pad. It is a graph which shows. It is the schematic which shows the method of measuring the vibration frequency of unusual noise. (A) is a graph showing the vibration frequency of the separation pad itself before changing the separation pad, and (B) is a graph showing the vibration frequency of the separation pad itself after changing the separation pad. It is the schematic which shows the measuring method of the vibration frequency of a separation pad. (A) is a graph showing the natural frequency of the spindle of the paper feed roller, and (B) is a graph showing the natural vibration frequency of the printer body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Separation pad 2 Support stand 3 Separation pad biasing spring 4 Paper feed roller 5 Paper cassette

Claims (6)

In a sheet feeding device that includes a sheet feeding roller that conveys a sheet and a separation pad that is pressed against the sheet feeding roller, and that passes between the sheet feeding roller and the separation pad, abnormal noise generated when the sheet is passed. A method for measuring the vibration of the separation pad, which is a cause,
Set a microphone near the paper feeder,
While recording the abnormal sound generated during the passage of paper with the microphone, the recorded abnormal sound is analyzed with a frequency analyzer to obtain the vibration frequency of the abnormal sound,
A pickup meter is attached to the transmission material that is fixed to the separation pad and pulled out, and the vibration of the separation pad during paper feeding is measured with the pickup meter through the transmission material, and the measured vibration is analyzed with a frequency analyzer. After obtaining the vibration frequency of the separation pad,
Compare the vibration frequency of the separation pad and the vibration frequency of the abnormal noise to derive a correlation,
After that, the separation pad vibration measurement method of the sheet feeding device that measures the vibration frequency of the abnormal sound and obtains the vibration frequency of the separation pad based on the correlation.   2. The separation pad vibration measurement method for a sheet feeding device according to claim 1, wherein the vibration frequency of the abnormal sound is set to be the vibration frequency of the separation pad, assuming that the vibration frequency of the abnormal sound is equal to the vibration frequency of the separation pad. Based on the vibration frequency of the separation pad obtained by the measurement method according to claim 1 or claim 2, a method of designing a paper feeding device that reduces abnormal noise,
A sheet feeding device other than the separation pad, including a support for supporting the separation pad, a separation pad biasing spring, a sheet cassette, a shaft of the sheet feeding roller, a bearing member of the shaft, and a housing material of the sheet feeding device. Designed so that the natural vibration frequency of the component member and the measured vibration frequency of the separation pad deviate from each other. By preventing resonance and resonance between the separation pad and the member, it is possible to reduce the occurrence of abnormal noise when passing paper. A design method of a paper feeding device as a component.   4. The supply according to claim 3, wherein the material of the separation pad, the friction coefficient, the weight, the shape, and / or the type of resin of the separation pad are changed in order to shift the vibration frequency of the separation pad from the natural vibration frequency. Paper device design method.   Separation pad supporting base other than the separation pad, separation pad biasing spring, paper feed roller shaft, bearing member, paper cassette, housing material shape, material, weight, or separation pad biasing spring The paper feeding device design method according to claim 3, wherein the natural vibration frequency is shifted from the vibration frequency of the separation pad by changing a spring pressure.   A sheet feeding device configured based on the design method according to claim 3.

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