WO1999046760A1

WO1999046760A1 - Precision apparatus having sound absorbing film

Info

Publication number: WO1999046760A1
Application number: PCT/JP1998/001810
Authority: WO
Inventors: Yasuyuki Ohira; Mitsuo Hori
Original assignee: Shishiai-Kabushikigaisha
Priority date: 1998-03-10
Filing date: 1998-04-20
Publication date: 1999-09-16

Abstract

A precision apparatus which has a built-in recording unit and in which noise generated inside the apparatus main part is absorbed and eliminated so as not to be recorded by the recording unit. Precision apparatuses having a built-in recording unit include recording/reproducing apparatuses using a magnetic medium such as tape recorders, MD recorders, and digital audio tape recorders (DAT recorders), and image recording/reproducing apparatuses such as video recorders and video cameras. In such a precision apparatus, a sound absorbing film preferably containing an active component for increasing dipole moments is provided inside the main part in order to prevent the recording unit from recording the noise generated inside the main part. If no contrivance is provided, the noise from the noise source is propagated through the air in the main part, spreads, and reaches the recording unit. Since the sound absorbing film is provided inside the main part, the noise is absorbed before it reaches the recording unit.

Description

Itoda »Precision equipment with sound-absorbing film Technical Field The present invention relates to precision equipment with a built-in recording unit. More specifically, the present invention relates to a precision device that absorbs and removes noise generated inside a device body so that a recording unit does not record noise. BACKGROUND ART Precision instruments with a built-in recording unit include recording and playback devices that use magnetic media, such as tape recorders, MD recorders, and digital audio tape recorders (DAT recorders), and video recording and playback, such as video recorders and video cameras. There are devices. Conventionally, for example, in a tape recorder or video camera, a rotating shaft is rotated by a motor, and with this rotation, a cassette type magnetic tape

(Sound or video recording medium) The magnetic tape unwound from one reel passes through the head in the process of being sent to the other reel, and the sound or video is recorded at this head. Recording or video recording) is to be played. However, since these tape recorders and video cameras have a built-in recording unit inside the device itself, when recording, in addition to the sound that should be originally recorded, it also includes noise generated inside the device itself. There was a problem that the sound could not be reproduced because it was picked up. Such technical problem, in the precision instrument which is adapted to run or rotate the magnetic tape or disk incorporates a ₃ particular motor had raw Ji Similarly for other precision equipment with a built-in recording unit also necessarily occur problem occurring _c, compact of precision equipment is to reduce the distance between the source of the recording unit and the noise inside the device body, and Manekuko the result that likely to cause failure due to noise As a result, the above-mentioned technical issues have become a theme that must be overcome while promoting compaction. The present invention has been made in view of such technical problems, and has as its object to provide a precision instrument that absorbs and removes noise generated inside an apparatus main body so that a recording unit does not record. is there. Disclosure of the Invention Examples of precision equipment with a built-in recording unit include recording and playback devices using magnetic media such as tape recorders, MD recorders, digital audio tape recorders (DAT recorders), and video recorders and video cameras. There are recording and playback devices. In such a precision instrument, in order to prevent the recording section from recording noise generated inside the apparatus main body, in the present invention, a sound absorbing film containing an active component for increasing the amount of dipole moment is provided inside the apparatus main body. Have been placed. The noise from the source propagates through the air and spreads inside the main unit to reach the recording unit.However, by placing a sound absorbing film inside the main unit, especially between the noise source and the recording unit. The noise is absorbed and removed before it reaches the recording section. FIG. 1 is a perspective view showing a state in which a sound absorbing film stretched on a frame having a predetermined thickness is arranged inside a tape recorder, and a sound absorbing effect of noise inside the tape recorder at this time is measured. FIG. 2 is a schematic diagram showing a dipole in the base material. FIG. 3 is a schematic diagram showing a state of a dipole in a base material when vibration energy is applied. Figure 4 is a schematic diagram showing the state of the dipole in the base material when the active ingredient is blended.

Fig. 5 is a graph showing the relationship between the dielectric constant (Ε ') and the dielectric loss factor における) of the resin matrix. Figure 6 shows the relationship between frequency and noise level obtained by the measurement device shown in Figure 1.

FIG. 7 is a perspective view showing a state where a plurality of types of sound absorbing films having sound absorbing peaks in different frequency regions are used, and a plurality of these sound absorbing films stretched on a frame having a predetermined thickness are arranged inside a video camera. FIG. 8 is a graph showing the measurement results of the noise level at each frequency for a video camera having a sound absorbing film disposed inside as shown in FIG. 7 and a video camera not disposed.

BEST MODE FOR CARRYING OUT THE INVENTION Regarding the arrangement of the sound absorbing film, it is arbitrarily determined where the sound absorbing film is located inside the device main body. There is no particular limitation, and it may be determined appropriately in consideration of the type, size, design, etc. of the device.However, from the viewpoint that sound can be absorbed more effectively, it is preferable that the distance between the recording unit and the source of noise is good. More preferably, the arrangement is in the vicinity of the recording section and surrounding the recording section. If the source of noise is limited to a predetermined location and it is clear that noise will only be generated from that location, a sound-absorbing film should be placed near the source and surrounding the source. It can also take the form. In this case, the noise generated from the source is absorbed and removed by the sound absorbing film before it propagates through the air and spreads inside the main body of the equipment. In addition, there are various types of noise generated inside the main body of the equipment. To cope with this, a plurality of types of sound absorbing films having sound absorbing peaks in different frequency regions can be arranged in combination. Even if a film with the same material and structure is used as the sound absorbing film, it can be made into a film that has sound absorption peaks in different frequency regions by changing the thickness, size, or shape. ₃ For example, the thicker the film (the thinner the film), the more the sound absorbing film

(Low frequency region). Also, as the size of the film is reduced (increased), the sound absorbing film has a sound absorption peak in a high frequency region (low frequency region). This sound absorbing film can also be stretched directly inside the device main body, but as shown in FIG. 1, it is stretched on a frame 3 having a predetermined thickness of, for example, 0.5 to 2 mm. Equipment (tape recorder) 1 It can be installed inside. In this case, since the sound absorbing film 2 is stretched over the frame 3 having a thickness, the sound absorbing film 2 can freely vibrate by the thickness of the frame 3. Therefore, noise transmitted from the source to the sound absorbing film 2 When a collision occurs, the sound can be reliably converted to vibration and absorbed and removed. In this case, a film having sound absorption peaks in different frequency regions can be obtained by changing the stretching state of the film, such as by strongly or loosely stretching the film on the frame. That is, when the film is stretched strongly on the frame, it has a sound absorption peak in a high frequency region, and when the film is stretched loosely on the frame, it has a sound absorption peak in a low frequency region. Also, the sound absorbing film does not use the frame as described above, and one end (for example, in the case of a film provided in a square shape, one side thereof) is directly fixed to the main body of the device. It can be made to hang inside the equipment itself. Next, the sound absorbing film itself that characterizes the present invention will be described. As a preferable example of the sound absorbing film, a polymer obtained by adding a polymer serving as a base material to an active component that increases the amount of dipole moment and forming a film is used. As the base material, for example, polyvinyl chloride, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, methyl polymethacrylate, polyvinylidene fluoride, polyisoprene, polystyrene, styrene-butadiene-acrylonitrile copolymer, styrene-acrylonitrile Copolymers, polymers such as acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR), and blends of these Can be used. Among them, polyvinyl chloride is preferable because it has good moldability and is inexpensive. The present inventors have elucidated the following sound absorption mechanism through research on sound absorbing materials. Vibration occurs when sound collides with the base material. At this time, as shown in FIG. 3, displacement occurs in the dipole 12 existing inside the base material 11. The displacement of the dipole 1 2 means that Check that each dipole 1 2 inside the base material 11 rotates or shifts in phase. It can be said that the arrangement state of the dipoles 12 in the base material 11 before the sound energy is applied as shown in FIG. 2 is in a stable state. However, as shown in Fig. 3, when the dipole 12 existing inside the base material 11 is displaced by the energy being applied to the base material 11 by the impact of sound, Dipoles 1 2 will be placed in an unstable state, and each dipole 1 2 will try to return to the stable state shown in Figure 2 _; this will consume energy. It is considered that the sound absorption effect is caused by the energy consumption due to the displacement of the dipole inside the base material and the restoring action of the dipole, and the energy consumption due to the generation of frictional heat on the surface of the base material. When considering such a sound absorption mechanism, the sheet resistance per unit area of the base material and the amount of dipole moment inside the base material 11 as shown in Figs. 2 and 3 greatly affect sound absorption. According to the experiments of the present inventors, the amount of dipole moment inside the base material 11 is such that the larger the amount, the more the performance of absorbing the energy of the sound of the base material 11 (the sound absorbing property) ) Was found to be higher. The amount of the dipole moment in the above-described base material varies depending on the type of the polymer serving as the base material. Even if the same polymer is used as the base material, the amount of dipole moment generated in the base material changes depending on the temperature and frequency of sound when sound is applied. The amount of dipole moment also changes depending on the magnitude of the sound energy applied to the base material. For this reason, it is desirable to select the polymer having the largest amount of dipole moment at that time in consideration of the temperature, sound frequency, energy level, and the like at the time of application, and use this as the base material. However, when selecting a polymer to be a base material, not only the amount of dipole moment in the base material, but also the handleability, formability, and ease of availability according to the application and use form of the sound absorbing film. It is desirable to take into account the properties, temperature performance (heat resistance and cold resistance), weather resistance, price, etc.-The active ingredient contained in this base material dramatically increases the amount of dipole moment in the base material The active component itself has a large dipole moment amount, or the active component itself has a small dipole moment amount. However, by mixing the active component, the dipole moment amount in the base material is increased. A component that can dramatically increase the amount of water. For example, the amount of dipole moment generated in the base material 11 under given temperature conditions, sound frequency, and energy level can be adjusted by adding an active ingredient to the same condition as shown in Fig. 4. Under these conditions, the amount will increase by a factor of three or ten. Along with this, the energy consumption due to the dipole restoring action when the above-mentioned energy is added will also increase dramatically, and the sound absorption effect due to the friction of the base metal surface will be added, which will make prediction much more It is thought that an excessive sound absorption effect will occur. Examples of active ingredients that induce such effects include N, N-dicyclohexylbenzobenzothiazyl-2-sulfenamide (DCHBSA), 2-mercaptobenzothiazole (MBT), dibenzothiazyl sulfide (MBTS), —Cyclohexylbenzothiazirue 2-sulfenamide (CBS), N-tert—butylbenzothiazirue-2-sulfenamide (BBS), N-oxyzetylene lenbenzothiazyl-12-sulfenamide (OBS), N, N A compound containing a benzothiazyl group, such as diisopropyl benzothiazirulu-2-sulfenamide (DPBS), and a benzotriazole with an azoyl group bonded to the benzene ring, and 2— {2 '—Hydroxy— 3 ′ — (3 ", A", 5 ", 6" tetrahydrophtalidamidemethyl) 1 5'—methylphenyl} —benzotriazole (2HPMMB) 2— {2'—Hydroxoxy 5'—methylphenyl} —Benzotriazole (2HMP B), 2- {2′Hydroxoxyl 3′-t-butyl-5′—Methylphenyl} — 5—Black benzotriazole (2HBMP CB), 2-{2 ′ —Hide mouth 3 ′, 5 ′ —Di-t-butylphenyl} 1-5—Black benzotriazole (2HDB PCB) ) Or one or more compounds selected from compounds containing a diphenyl acrylate group such as ethyl 2-cyano 1,3,3-diphenyl acrylate be able to. Some resins have benzophenone groups such as 2-hydroxy 4-methoxybenzophenone (HMBP) and 2-hydroxy-4-methoxybenzophenone-15-sulfonic acid (HM BPS). One or more selected from compounds can be mentioned. Incidentally, the amount of dipole moment in the above-mentioned active component varies depending on the type of active component similarly to the amount of dipole moment in the base material. Even when the same active ingredient is used, the amount of dipole moment generated in the base metal changes depending on the temperature when sound energy is applied. Also, the amount of dipole moment changes depending on the magnitude of the sound energy applied to the base material. For this reason, it is desirable to select and use the active component that gives the largest amount of dipole moment in consideration of the temperature and energy at the time of application. When deciding the active ingredient to be blended in the base material, it is good to select the one with a similar value in consideration of the compatibility between the active ingredient and the polymer as the base material, that is, the SP value. The sound-absorbing film of the present invention may contain, if necessary, a corrosion inhibitor, a dye, and the like, in addition to the polymer serving as the base material and the above-mentioned active component. In addition, a conventionally known method can be used as a molding method when the above components are blended and the blend is formed into a film. As described above, the sound-absorbing film in which the active material is contained in the base material dramatically increases the amount of dipole moment in the base material, thereby exhibiting excellent sound energy absorbing performance (sound absorbing property). However, the amount of dipole moment in this sound absorbing film is expressed as the difference in the dielectric constant between A and B shown in Fig. 5 _c ), that is, the dielectric constant between A and B shown in Fig. 5. difference etc. ho larger the a (), now ₃ it comes to the amount of dipole mode one instrument is large, FIG. 5 is Ru graph der showing the relationship between the dielectric constant () and the dielectric loss factor 〃) . As shown in this graph, there is a relationship between the permittivity () and the permittivity 〃) such that the permittivity 〃) = the permittivity) X the dielectric loss tangent (tan 0). The present inventor has found through research on sound absorbing materials that the higher the dielectric loss factor 〃) here, the higher the energy absorption performance (sound absorption). Based on this finding, the above-described sound absorbing film was examined for the dielectric loss factor 〃). When the dielectric loss factor at a frequency of 11 OHz was 7 or more, the sound absorbing film exhibited excellent energy absorption performance (sound absorbing performance). ). The sound-absorbing film of the present invention may be laminated with a sound-insulating sheet or laminated with another type of sound-absorbing sheet, for example, a foamed sound-absorbing sheet, a fiber sheet, or paper. Example Example 1

As shown in FIG. 1, 100 parts by weight of DCHB SA was added to chlorinated polyethylene to a frame 3 having a thickness of 0.5 mm, and a sound absorbing film 2 formed into a sheet having a thickness of 0.1 mm was obtained. Fix the stretched unit inside the tape recorder 1 with double-sided tape (not shown). Next, the tape recorder 1 was set to the recording state, and the sound (noise generated inside the tape recorder) that entered through the built-in microphone 4 was taken out by the earphone jack 5, and the frequency was analyzed by the FFT analyzer (CF 350) 6. Figure 6 shows the results. For comparison, a frequency analysis was also performed for the case where the sound absorbing film 2 was not disposed inside (untreated), and is shown in FIG. From FIG. 6, it was confirmed that when the sound absorbing film of this example was used, the noise generated inside the tape recorder was effectively absorbed over a wide frequency range from about 300 Hz to about 3000 Hz. In particular, a high absorption exceeding 5 dB was confirmed in the range of 400 Hz to 80 OHz. Example 2

As shown in Fig. 7, 100 parts by weight of DCHB SA is added to chlorinated polyethylene to six types of frames 3 having a thickness of 0.5 mm, different sizes and shapes, and a thickness of 0.1 mm. The sound-absorbing films 2 formed into sheets are stretched with the same tension, and these are fixed inside the video camera 1 with double-sided tape (not shown). Next, the video camera 1 was set to a recording state, and the sound (noise generated inside the video camera) entering through the built-in microphone 4 was measured and frequency analysis was performed in the same manner as in Example 1. Figure 8 shows the results. For comparison, a frequency analysis was also performed for the case where the sound absorbing film 2 was not disposed inside (untreated), and the results are shown in FIG. From Fig. 8, when the sound-absorbing film of this example is used, the noise generated inside the video camera is effectively absorbed over a wide range of frequencies from about 100 to 200 Hz and from about 1,000 Hz to about 5000 Hz. High absorptions of more than 5 dB were observed, especially in the range 1500 Hz to 2000 Hz.

Claims

Scope of word blue

1. A precision instrument having a built-in sound recording section, wherein a sound absorbing film is disposed inside the instrument body in order to prevent noise generated inside the instrument body from being recorded by the pre-recording sound section.

2. The precision device according to claim 1, wherein a plurality of types of sound absorption films having sound absorption peaks in different frequency regions are combined and arranged inside the device main body.

3. The precision device according to claim 1, wherein the sound absorbing film contains an active component that increases a dipole moment amount.

4. The precision device according to claim 3, wherein the active ingredient contained in the sound absorbing film is one or more kinds selected from a compound containing a benzothiazyl group.

5. The precision device according to claim 3, wherein the active component contained in the sound absorbing film is one or more selected from compounds having a benzotriazole group.

6. The precision device _{3 according} to claim 3, wherein the active ingredient contained in the sound absorbing film is one or more kinds selected from compounds having a diphenylatylate group.

7. The precision device according to claim 3, wherein the active component contained in the sound absorbing film is one or more selected from compounds having a benzophenone group.

8. The method according to any one of claims 3 to 7, wherein the active ingredient is contained in a proportion of 10 to 300 parts by weight with respect to 100 parts by weight of a resin constituting the sound absorbing film. Precision equipment.

9. The sound-absorbing film precision instrument according to any one of claims 3-8 for dielectric loss factor at frequency 1 1 OH _Z is equal to or is 7 or more.

10. The precision device according to any one of claims 1 to 9, wherein the sound absorbing film is arranged near the recording portion.

11. The precision device according to any one of claims 1 to 10, wherein the sound absorbing film is arranged so as to surround the recording portion.

12. The precision device according to any one of claims 1 to 9, wherein the sound absorbing film is arranged near a source of the noise.

13. The precision device according to any one of claims 1 to 9, wherein the sound absorbing film is arranged so as to surround the noise generation source.

14. The precision instrument according to any one of claims 1 to 13, wherein the sound absorbing film is stretched on a frame having a predetermined thickness.

15. The precision device according to any one of claims 1 to 13, wherein one end of the sound absorbing film is fixed to the device main body.

16. The precision device according to any one of claims 1 to 15, wherein a porous sound absorbing sheet is laminated and integrated with the sound absorbing film.