JP2001306078A - Sound insulating device for precision equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound insulating device for precision equipment which can effectively suppress the influence of sounds on the device. SOLUTION: The sound insulating device, mounted with sound-insulating plates 17 via interposed material 16 on the surface of the precision equipment, is constituted by using materials which are sufficiently higher in the natural frequency of the single substance of the insulating plates 17 than the frequencies to be sound-insulated and/or have a large internal loss as the insulating plates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sound insulation device for precision equipment such as an electron microscope.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing an example of an external configuration of an electron microscope. In this type of electron microscope, the microscope body 1
Are mounted on the base plate 2, and anti-vibration mounts 3 are provided at four corners of the base plate 2. The bottom surface of the anti-vibration mount 3 is fixed to the gantry 4. The gantry 4 is placed or fixed on a floor 5.

[0003] Vibrations input to this type of electron microscope include mechanical vibration input to the gantry 4 via the floor 5 and
There is a sound input to the microscope main body 1 through the air. Among them, the mechanical vibration input from the floor 5 is almost eliminated by the anti-vibration mount 3.

On the other hand, when the apparatus is exposed to external sound, sound is input from the entire surface of the apparatus and transmitted to the microscope main body 1 and a sample stage (not shown) for holding a sample for observation. And as a result, noise may appear in the scanned image.

[0005]

In this case, since a sensitive acoustic frequency range exists depending on the characteristics of each device, it is a practical measure to prevent sound within the frequency range from being input to the device. Is effective as

[0006] Generally, in order to reduce the sound incident on the apparatus, a method of putting the entire apparatus in a soundproof room or the like is employed. However, this method is expensive and is considerably heavy. In addition, there is a problem that the installation environment is limited, for example, a high floor strength is required.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an inexpensive and lightweight sound insulation device for precision equipment, which can effectively suppress the influence of sound on the device. It is an object.

[0008]

According to a first aspect of the present invention, there is provided a sound insulation device in which a sound insulation plate is attached to the surface of a precision instrument via an intervening object, wherein the natural frequency of the sound insulation plate alone is sound insulation. It is characterized in that a material having a sufficiently higher internal frequency than the frequency to be used and / or having a large internal loss is used as the sound insulating plate.

[0009] With this configuration, it is possible to remove an acoustic frequency that is sensitive to the device, so that the effect of sound on the device can be effectively suppressed. (2) In the sound insulation device according to the second aspect of the present invention, in which a sound insulation plate is attached to the surface of a precision instrument via an inclusion, the frequency of the natural vibration generated by the inclusion is sufficiently higher than the frequency to be sound-insulated. It is characterized by using a material having a low loss factor and / or a large loss coefficient as the inclusion.

[0010] With this configuration, it is possible to remove an acoustic frequency that is sensitive to the device, and it is possible to effectively suppress the influence of sound on the device. (3) In the sound insulating device according to the third aspect of the present invention, wherein a sound insulating plate is attached to the surface of a precision instrument via an intervening object, the natural frequency of the sound insulating plate alone is sufficiently higher than a frequency at which sound is to be isolated. And the frequency of the natural vibration generated by the inclusion is sufficiently lower than the frequency of the sound insulation.

According to this structure, an acoustic frequency which is sensitive to the apparatus can be removed, so that the influence of the sound on the apparatus can be effectively suppressed. (4) The invention according to claim 4 is characterized in that between the plurality of sound insulation plates,
It is characterized in that the gap between the sound insulating plate and the surface of the device is reduced, and the sound input through the inclusion is reduced by utilizing the characteristics of the inclusion itself.

With this configuration, it is possible to reduce the influence of a sound input that is sensitive to the device. (5) The invention described in claim 5 is characterized in that the whole precision instrument or a part thereof is covered with a box-shaped structure composed of a sound insulation plate and an inclusion.

With this configuration, it is possible to realize an effective sound insulation structure for precision equipment.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of the present invention. In the figure, 15 is the surface of the device, 16 is an inclusion mounted in contact with the surface 15 of the device, and 17 is a sound insulation plate mounted so as to cover the surface of the inclusion 16. The sound insulation plate 17 is divided and attached, and a gap 18 is formed between the sound insulation plates. 19 is a gap formed between the apparatus main body and the sound insulating plate 17. Here, as the inclusions 16, for example, a foamed resin having a closed cell structure having relatively low rigidity is used. As the sound insulating plate 17, for example, one having a thickness of several mm is used. Between the device surface 15 and the inclusion 16 and the inclusion 1
6 and the sound insulating plate 17 are fixed by, for example, an adhesive. To explain the operation of the device configured as described above,
It is as follows.

When sound enters the device surface 15 from the outside, the sound is blocked by the sound insulating plate 17 and the amount of sound input to the device is reduced. According to the mass law, the sound insulation performance increases as the mass per unit area increases. At this time, the natural frequency of each sound insulating plate 17 alone is designed to be higher than the acoustic frequency range that is sensitive to the device, so that the sound insulating plate 1
The phenomenon that the sound transmittance increases due to the natural vibration of No. 7 can be practically avoided. Dividing the sound insulating plate 17 is effective in increasing the natural frequency of each sound insulating plate 17 alone.

The acoustic energy incident on the sound insulating plate 17 is
This is converted into mechanical vibration of the sound insulating plate 17. This mechanical vibration
It reaches the device surface 15 in accordance with the vibration transmission characteristics of the system formed by the inclusion 16 and the sound insulating plate 17. At this time, the transmission rate of this vibration can be reduced by designing the natural frequency of the vibration mode formed by the sound insulating plate 17 and the inclusion 16 sufficiently lower than the acoustic frequency range that is sensitive to the device. .

FIG. 2 is an explanatory diagram of a vibration model according to the present invention. In the figure, 30 is a fixed object, 31 is a spring, and 32 is an object having a mass of m. The spring 31 has a spring constant k per unit area of the inclusion 16, and the mass m is
Assuming that the mass per unit area is 7, the natural angular frequency ω of the one-degree-of-freedom system is expressed by the following equation.

Ω = √ (k / m) The material and thickness of the inclusion 16 and the thickness of the sound insulation plate 17 are adjusted so that √2 times the natural angular frequency ω is the lower limit frequency at which sound insulation is desired. Thus, transmission of vibration of the sound insulating plate can be attenuated.

As described above, the natural frequency of the sound insulating plate 17 alone is sufficiently high (for example, about 1.5 kHz) for a frequency range (for example, 100 to 1 kHz) that is sensitive to a device that dislikes vibration. By designing the frequency of the natural vibration between the object 16 and the sound insulating plate 17 to be sufficiently low (for example, about 70 Hz), it is possible to avoid the sensitive frequency range, and to realize a practical sound insulating structure. The mechanism of the present invention can be designed to be inexpensive and lightweight compared to a large soundproof room that surrounds the entire device.

However, regarding the structure of the present invention, it is necessary to make the sound input from the gap 18 between the sound insulating plates and the gap 19 between the device and the sound insulating plate as small as possible. In the present embodiment, the influence of the sound input from these gaps is reduced by reducing the total area of the air flow path by employing a foamed resin having a closed cell structure as the inclusion 16. be able to.

By using a material having a large internal loss, such as a vibration damping material or lead, as the material of the sound insulating plate 17, the influence of the natural vibration of the sound insulating plate 17 alone on the deterioration of the sound insulating characteristics can be reduced. Thereby, the sound insulating plate 17 to be used is
Increase each area, reduce the number of sheets used,
By reducing the total area of the gaps 18 between the sound insulating plates, an effect is obtained that the sound input can be reduced.

Also, by using a material having a high loss coefficient for the inclusions 16, the resonance peak at the time of natural vibration with the sound insulating plate 17 can be suppressed low, and the amount of vibration transmission can be reduced.

FIG. 3 is a block diagram showing another embodiment of the present invention. In this embodiment, the electron microscope body is covered with a box-shaped structure 20. Figure 1,
The same components as those in FIG. 4 are denoted by the same reference numerals. As the box-shaped structure 20 covering the entire device, a rectangular parallelepiped, a cylindrical shape,
Those having a spherical shape or the like are used.

This structure is used for purposes such as sound insulation, wind shielding, electromagnetic shielding, temperature control around the device, or simply a cover for protecting the device. Since this structure is generally made of a plate-shaped member having a large area, its primary natural frequency is generally low. There are an infinite number of natural vibration modes in this structure in the higher frequency range.Resonance phenomena occur around each frequency, so from the standpoint of sound insulation, sound insulation performance that conforms to the mass rule can be obtained. become unable.

Therefore, in the present invention, the structure including the inclusions 16 and the sound insulating plate 17 described above is attached to the surface of the box-shaped structure 20 covering the entire device by means of an adhesive or the like. According to the principle already described, it is possible to realize a sound insulation structure effective for sound in a frequency band that affects the performance of the device. When this structure is used for other purposes, it can provide sound insulation to enhance the device's acoustic performance.

In the figure, the whole device is shown so as to surround it. However, a certain effect can be obtained even if only the upper half and the lower half of the device or each is surrounded by a separate sound insulation structure. Of course, it is also possible to attach a door so that it can be partially opened and closed. In addition, even if there is no box-shaped structure 20, if there is only a frame structure for supporting the inclusion 16, the present sound insulation structure works effectively.

In the above embodiment, the case where the present invention is applied to an electron microscope as a precision instrument is taken as an example. However, the present invention is not limited to this, and the present invention is similarly applicable to other kinds of precision instruments. Can be.

[0028]

As described above, according to the present invention, the following effects can be obtained. (1) According to the first aspect of the present invention, since an acoustic frequency that is sensitive to the device can be removed, the effect of sound on the device can be effectively suppressed.

(2) According to the second aspect of the present invention, since an acoustic frequency which is sensitive to the device can be removed, the influence of sound on the device can be effectively suppressed. (3) According to the third aspect of the present invention, an acoustic frequency that is sensitive to the device can be removed, so that the influence of sound on the device can be effectively suppressed.

(4) According to the fourth aspect of the invention, it is possible to reduce the influence of a sound input that is sensitive to the device. (5) According to the fifth aspect of the invention, an effective sound insulation structure for precision equipment can be realized.

As described above, according to the present invention, it is possible to provide an inexpensive and lightweight sound insulation device for precision equipment, which can effectively suppress the influence of sound on the device.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a vibration model according to the present invention.

FIG. 3 is a configuration diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing an example of an external configuration of an electron microscope.

[Explanation of symbols]

 15 Device Surface 16 Inclusion 17 Sound Insulation Plate 18 Gap Between Sound Insulation Plates 19 Gap Between Device and Sound Insulation Plate

Claims (5)

[Claims] 1. A sound insulation device in which a sound insulation plate is attached to the surface of a precision instrument via an intervening object, wherein the natural frequency of the sound insulation plate itself is sufficiently higher than a frequency to be sound-insulated, and / or A sound insulation device for precision equipment, characterized by using a material having a large loss. 2. A sound insulation device in which a sound insulation plate is attached to the surface of a precision instrument via an inclusion, wherein a frequency of a natural vibration generated by the inclusion is sufficiently lower than a frequency to be sound-insulated, and / or A sound insulation device for precision equipment, characterized by using a material having a large loss coefficient. 3. A sound insulation device in which a sound insulation plate is attached to the surface of a precision instrument via an inclusion, wherein a natural frequency of the sound insulation plate alone is sufficiently higher than a frequency to be sound-insulated, A sound insulation device for precision equipment, wherein a frequency of a natural vibration generated by the inclusion is sufficiently lower than a frequency to be sound-insulated. 4. The method according to claim 1, wherein a gap between the plurality of sound insulation plates and a gap between the sound insulation plate and the surface of the device are reduced, and a sound input through the inclusion is reduced by utilizing characteristics of the inclusion itself. The sound insulation device for precision equipment according to claim 1. 5. A sound insulation device for a precision instrument, wherein the whole or a part of the precision instrument is covered with a box-shaped structure composed of a sound insulation plate and inclusions.