JPS5912785Y2 - Noise prevention shutter for air column in magnetic recording and reproducing equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a noise prevention shutter for an air column in a VTR. This invention relates to a system that effectively suppresses generated noise and facilitates the loading of magnetic tapes.

Conventionally, two sets of reels, drums, capstans, control heads, etc. were prepared, two systems were provided for running the magnetic tape, and each system's magnetic tape was controlled to run and stop intermittently one field at a time. 2. Description of the Related Art VTRs are known in which recording or reproduction is performed on each magnetic tape, thereby handling continuous television signals.

According to this system, by running the magnetic tape at appropriate timing and controlling the speed of the rotating drum arbitrarily, still images and slow-motion images can be obtained continuously and reliably, which was not possible until now. It is possible to eliminate the drawbacks of the helical scan method, such as noise being generated in the reproduced image and synchronization being easily disrupted.

By the way, in such a VTR, in order to feed the magnetic tape intermittently with high frequency as mentioned above, a part of the magnetic tape is guided into the air column, and a suction blower blows the air in the air column. At this time, compressional waves are formed within the air column, and the impact sound generated by this, together with the resonance effect depending on the length of the air column, becomes a large noise. , the sound was emitted outside the VTR, which caused problems in use.

The present invention provides a noise prevention shutter for preventing such impact noise from leaking to the outside, and embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a front view schematically showing a VTR according to the present invention.
is the VTR body, and there are two rotating drums 2 on the top.
, 3 are attached, and at the bottom of each rotating drum 2.3,
A pair of reels each serving as supply and winding reels 4. 5. 6. 7, capstans 8, 9, control spatulas) '10, 11° guide pins 12 to 21 and 22 to 31 are provided.

Further, air columns 32, 33, 34, 35 whose interiors are substantially sealed are provided at the bottom of each of these members, and the guide pins 13.degree. 14, 20.21, and 23.24. Magnetic tapes 36 and 37 guided by tapes 30 and 31 are housed in approximately the same manner.

38 to 41 are mode selection switches for recording and reproduction, 42 and 43 are level meters for recording and reproduction, and 44 is a power switch.

What is important here is that a gap is provided between the upper plates 45, 46, 47, 48 of the air columns 32 to 35 and the side plates of the air column to allow the guide of the magnetic tape 36, 37. Yes, and the magnetic tape 36.37
The purpose is to make it possible to adjust the air gap so that the air can be accommodated inside the air columns 32 to 35.

Fig. 2 is a perspective view showing details of the vicinity of the upper plates 45 to 48, Fig. 3 is a front view of the main part, Fig. 4 is a side sectional view, and Fig. 5 is the main part with the presser plate removed. FIG.

Here, 49 is a mounting board that constitutes the air columns 32 to 35. Between the side plates 50, 51 and the front plate 52, which together with this mounting board 49 constitute the air columns 32 to 35, are attached as shown.

That is, the upper plates 45 to 48 include a trapezoidal base plate 53 which is a trapezoidal piece made of metal, an operating rod 54 attached to the trapezoidal base plate so as to be freely retractable in the front-rear direction, and the operating rod 54.
The two opening/closing plates 55 and 56 that can be moved in the left and right direction depending on the appearance and appearance of the The opening/closing plates 55 and 56 are biased and moved by the operating rod 54 to constitute a shutter member.

A through hole 60 on the mounting piece 59 standing up on the base plate 53
A screw 61 is inserted into the mounting board 49 to fix it to the mounting board 49.

The base plate 53 also has air holes 6 that pass through the top and bottom.
2 is installed.

Furthermore, a lower protrusion 63 is provided at the lower center of the base plate 53.
The two opening/closing plates 55 and 56 on the left and right sides are attached so as to sandwich the lower protrusion 63 and slide along the lower part of the base plate 53.

Each of the opening/closing plates 55 and 56 has two elongated holes 6.
4.65 are provided as shown in FIG. 5, and these are loosely fitted into two protrusions 66 and 67 protruding from the lower surface of the base plate 53, so that the amount of sliding in the left and right direction is regulated. It's becoming like that.

In addition, in order to finely adjust the amount of sliding, the elongated hole 64,
Adjustment screws 68 and 69 that protrude and retract inside 65 are provided near the elongated holes 64 and 65 so that their tips face the projections 66 and 67.

Reference numeral 70 denotes a set screw screwed into the operating rod 54 so as to move within a notch 71 provided on the lower surface of the base plate 53 and having a sound-deadening effect.
A whisker spring 74 as shown in the figure is locked between setscrews 72 and 73 screwed into the actuating rod 5.
4 is always urged forward, and the opening/closing plates 55 and 56 are urged outward.

In addition, the presser plate 5 is placed so as to cover the lower surface of the opening/closing plate 55 and 56.
7 are superimposed on each other, and this presser plate 57 is fixed to the base plate 53 by set screws 75 and 76 which are screwed into the projections 66 and 67.

This presser plate 57 is provided with a through hole 77 that communicates with the through hole 62 drilled in the base plate 53, and the air in the air column is gradually released to the outside through these holes. It looks like he's running away.

In FIG. 4, reference numeral 78 denotes an opening/closing lid which is provided on the top of the front plate 52 so as to be openable and closable, and which rotates around a support shaft 79 and is held in the closed state by a predetermined locking means. It's becoming like this.

According to the air column noise prevention shutter having such a structure, first, when replacing the magnetic tapes 36, 37, the opening/closing cover 78 is opened to the position shown by the solid line as shown in FIG.

Then, the operating rod 54 receives the elastic force of the beard spring 74 and protrudes forward, and at the same time the opening/closing plate 5
6.57 is housed inward from both end surfaces of the base plate 53, and therefore there is a relatively large gap (on the order of several millimeters) between these end surfaces and the air column side plates 50 and 51. ) are formed to facilitate the placement of the magnetic tapes 36, 37 within the air columns 32-35.

In addition, after storing the magnetic tapes 36 and 37, the opening/closing lid 7
8 is closed to the position shown by the chain line, the operating rod 54 is pushed into the interior against the elastic force of the sink spring 74, and the opening/closing plates 55 and 56 move in the left-right direction, causing the above-mentioned It is held in place with a minimum gap between it and the side plates 50,51.

Note that the end surfaces of these opening/closing plates 55 and 56 are connected to the magnetic tape 3.
6.37 is finished with a smooth surface so as not to damage it.

In this way, when the VTR is placed in the magnetic tape intermittent feed mode and recording or playback is performed after the magnetic tapes 36 and 37 have been accommodated in the air columns 32 to 35, the noise generated as described above is absorbed by the air columns 32 to 35. The impact sound is contained within the columns 32 to 35, and due to the sound absorption and soundproofing effects of the sound absorbing material 58, it is possible to effectively suppress leakage of impact sound to the outside of the air columns 32 to 35.

Note that this type of sound absorbing material and sound insulating material are used in air columns 32 to 3.
It is preferable to apply it to the entire inside of the container.

By providing the noise prevention shutter in this way, it is possible to reliably suppress the impact noise generated from the air column, and the magnetic tape can be easily loaded and broken.

The noise generated in the air columns 32 to 35 is generated when the magnetic tape in these air columns is sucked downward by the exhaust operation of the suction blower, as shown in FIG. The air in the upper part A is compressed or diluted to form compression waves, which are amplified by the resonance of the air columns 32 to 35 and are emitted to the outside as loud noise.

Looking at this from another angle, in the state immediately before the intermittent feed operation shown in Figure 7, the spot B is a part where air molecules are thin due to the suction blower, but due to the intermittent feed of about 4 mm, As shown in FIG. 8, a vacuum section of about 1 cc is rapidly formed in section C.

Then, at the next moment, air at atmospheric pressure enters this vacuum section, and the 9th
As shown in the figure, the impact sound of the vacuum section C collapsing occurs in a concentrated manner for the first time.

If we look at such a situation, the above air column 32.33
and 34.35 are operated alternately in 1 field (body second) increments. Paying attention to this operation, actively send an impulsive sound wave to the vacuum section C, so that the generated shock waves are mutually activated. Can be offset.

For this reason, the impact sound can be suppressed by attaching a speaker facing the atmospheric pressure forming portion of the air columns 32 to 35 and superimposing the negative phase sound wave on the shock wave.

Furthermore, since the air columns 32.33 and 34.35 are in a completely opposite phase relationship in terms of compression causes and vacuum causes, these two columns 32.33 and 34.35 are connected to the vacuum section C using pipes or the like. By communicating with each other, the above-mentioned noise can be canceled out in terms of sound pressure.

Further, in order to prevent the noise from leaking out of the main body 1 of the VTR, the main body 1 can be covered with a lid 81 via a seal member 80 as shown in FIG.

In this case, the sealing member 80 is fitted onto the lid body 81 as shown in FIG. By enclosing gas at a higher pressure than the outside air, the lid 81 can be sealed against the main body 1, and effective sound insulation can be achieved.

The sealing member 80 adapts to the slight unevenness of the main body 1 and also has the effect of cushioning the impact, and its shape retention and long life are unparalleled. It is.

As described above, according to the present invention, in a magnetic recording and reproducing apparatus in which a magnetic tape that is intermittently fed is guided by an air column whose atmospheric pressure is controlled by a suction blower, a substrate portion having a through hole is provided. A shutter member is composed of an operating rod that moves in and out of the base plate, and an opening/closing plate that is energized by the projection and retraction of the operating rod, and the shutter member is constructed by leaving gaps on the left and right sides of the upper part of the air column. By opening and closing the opening/closing cover arranged in front of the air column, the operating rod is exposed and retracted, and the opening/closing plate is controlled to open and close. The leakage of impact noise to the outside can be effectively suppressed, which is extremely beneficial in practical use.

Further, the configuration for obtaining such effects also has various effects such as being simple and inexpensive.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a front view schematically showing a VTR; FIG. 2 is a perspective view of a noise prevention shutter according to the present invention; FIG. 3 is a front view of the main parts; 4 is a side sectional view, FIG. 5 is a bottom view with the presser plate removed, and FIGS. 6 to 9 are explanatory diagrams showing the order in which shock waves are formed. FIG. 10 is a perspective view of the main body 1 covered with a lid;
FIG. 11 is a sectional view of the main parts showing the structure. 32, 33.34.35...air column, 36.37
. . . Magnetic tape, 53 . . . Substrate portion, 54 . . . Operating rod, 55 .
Sound absorbing material, 62... Through hole, 74... Spring, 77
...Through hole, 78...Opening/closing lid.

Claims (1)

[Scope of utility model registration request] In a magnetic recording/reproducing device in which an intermittently fed magnetic tape is guided by an air column whose air pressure is controlled by a suction blower, a base plate having a through hole and an operating rod that moves in and out of the base plate are used. and an opening/closing plate that is energized by the protrusion and retraction of the operating rod, and the shutter member is arranged in the upper part of the air column with gaps left and right on the left and right, and the shutter member is arranged in front of the air column. 1. A noise prevention shutter for an air column in a magnetic recording/reproducing device, characterized in that the operating rod is moved in and out by opening and closing the opening/closing lid to control opening/closing of the opening/closing plate.