JP3439566B2 - Recording and playback device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting mechanism for positioning a drum on a mechanism substrate in a recording / reproducing apparatus such as a VTR, DAT, helical scan data recorder, etc., and particularly fixing the drum with screws. The present invention relates to a mounting mechanism having a drum mounting surface shape suitable for reducing deformation of a drum due to a tightening force of a screw when holding the drum and improving linearity of a signal track recorded on a tape.

[0002]

2. Description of the Related Art In a recording / reproducing apparatus using a tape as a medium, such as a VTR, DAT, or a helical scan data recorder, in order to ensure compatibility with other devices of the same standard, the linearity of a signal track on the tape. Need to keep good. One of the factors that deteriorates the track linearity is the deformation of the drum lead portion, which is a factor that directly changes the linearity of the recording track.

FIG. 9 is a perspective view showing the shape in the vicinity of the rotary drum 4 described above. The drum 4 is composed of a lower drum 8 fixed at a predetermined position on a chassis (not shown), and an upper drum 9 rotatably supported coaxially with the lower drum 8. The tape 2 is a tape guide 10,
The tape 2 is obliquely wound around the drum 4 by 11, 12, and 13, and at this time, the tape 2 is wound over the surfaces of the lower drum 8 and the upper drum 9. Tape 2 is lower drum 8
In the case of normal recording / reproducing, the lower end is regulated by a step called a lead 3 provided on the surface of the disk, and the disk travels in the direction of arrow A at a predetermined speed. The head 1 is provided so as to protrude from the drum surface by a predetermined amount through a gap provided between the lower drum 8 and the upper drum 9. Head 1 is upper drum 9
And rotates in the direction of arrow B at a high speed coaxially with. At this time, the tip of the head 1 obliquely scans the tape 2, records a signal on the surface of the tape 2, and reproduces the signal recorded on the tape 2. The drum 4 is mounted and fixed on a drum base 15 which is fixed on a chassis (not shown).

10 and 11 are conceptual diagrams for explaining the recording state of the recording track 19 helically recorded on the tape 2. As shown in FIG. 10A, the tape 2 travels with the lower end guided by the leads 3 to form a recording track 19. Arrow A indicates the running direction of the tape 2,
The arrow B indicates the scanning direction of the head 1 indicated by the broken line in FIG. When the lead portion 3 has good linearity,
As shown in (B), the linearity of the recording track 19 is good. Recording track 1 obtained by such recording
The reproduced waveform 20 when reproducing 9 is a good waveform that a predetermined output with a constant amplitude can be obtained as shown in FIG.
Therefore, compatibility of the player is sufficiently guaranteed. On the other hand, when the lead portion 3 is deformed as shown in FIG. 11 (A), the tape 2 is guided so as to make a wave following the deformation of the deformed lead portion 3, and thus the tape 2 is guided to the tape 2. The formed recording track 19 is formed in a wavy shape as shown in FIG. 11B, and the linearity of the recording track 19 deteriorates.

A tape 2 recorded by a recording apparatus having a normal lead portion 3 in the state shown in FIG. 10A is shown in FIG.
When the lead unit 3 in the state of FIG. 11 is mounted on a reproducing apparatus in which the lead unit 3 is deformed and is reproduced, or when the lead unit 3 in the state of FIG.
The tape 2 recorded by the recording device in which the
When mounted in a recording apparatus having a normal lead section 3 in the state of (A) and reproduced, as shown in FIG. 13, the reproduction output of the recording track fluctuates and the reproduced waveform 20 deteriorates, leading to a significant performance deterioration. . Further, in such a state, the signals of the adjacent tracks are also partially read to cause crosstalk, which significantly deteriorates the quality of the reproduced signal. Further, the deformation of the lead portion 3 is one of the causes of unstable tape running, and there is a possibility that signal recording / reproduction cannot be performed accurately.

The linearity of the lead 3 as described above largely depends on the processing accuracy when cutting the drum. However, even if the lead is processed with high precision, if the drum is deformed by tightening the screw when fixing the drum at a predetermined position on the mechanism substrate of the recording / reproducing apparatus, the linearity of the lead will be reduced. to degrade.

FIG. 14 is a perspective view showing the shapes of the conventional drum base 15 and the drum 4 and their relationships. However, the drum 4 is shown separately above the drum base 15. Three drum mounting surfaces 7 ′ are provided on the drum base 15. The drum 4 is fixed to the drum base 15 by bringing the bottom surface 6 of the lower drum 8 into contact with the drum mounting surface 7 ′, tightening the screw 5 in the direction shown in the drawing, and fixing the drum base 15.

The drum mounting surface 7'is provided with screw holes 16 on the outside of screw holes 16 provided on the drum base 15 for inserting the three screws 5 for fixing the drum 4 to the drum base 15. It is formed coaxially and annularly. The three drum mounting surfaces 7 ′ are provided on the same plane and contact the bottom surface 6 of the lower drum 8 to define the height, the inclination angle and the inclination direction of the drum 4.

FIG. 15 shows a screw 5 for fixing the drum 4.
It is sectional drawing which shows the condition of the vicinity. When the processing accuracy of the drum mounting surface 7'is low, protrusions 17 are formed as shown in the figure.
The drum 4 is placed on the drum mounting surface 7 ′ having such a protrusion.
The bottom surface 6 of the lower drum 8 does not come into contact with the entire surface of the drum mounting surface, and the drum 4 is obliquely fixed to the drum mounting surface 7 '. Further, since the tightening force f of the screw is applied in the direction of arrow C in the drawing, a torque obtained by multiplying the lower drum 8 by the tightening force f and the distance 1 from the center of the screw hole 16 to the protrusion 17 is applied. Further, since torque due to the tightening force of the screws on the other two drum mounting surfaces 7'is also applied, the lower drum 8 is deformed and the linearity of the leads 3 formed on the lower drum 8 is deteriorated.

Generally, the bottom surface of the drum is held by the drum mounting surface 7'and is fixed at a predetermined position of the recording / reproducing apparatus. The drum mounting surface 7'is usually composed of three small surfaces arranged on the same plane. These three surfaces are arranged at the positions of the vertices of a substantially equilateral triangle smaller than the bottom surface of the drum, and contact with the bottom surface 6 of the lower drum 8 at three points by the tightening force of the screw 5 that fixes the drum 4,
The height and the inclination angle of the drum bottom surface 6 are defined. In the conventional drum mounting surface, three surfaces are arranged in a substantially equilateral triangle as described above, and each mounting surface is often formed in an annular shape coaxial with a screw hole through which a screw for fixing the drum is inserted. . This is to prevent the deformation of the drum by reducing the torque applied to the drum by the tightening force of the screw by reducing the distance between the drum mounting surface and the mounting position of the screw.
This prevents the linearity of the leads from deteriorating. For example, in Japanese Patent Laid-Open No. 2-254663,
Such an example is described, and the example can be found in products such as VHS-VTR and 8 mm video camera which have been released so far.

As described above, in the prior art, as shown in FIG. 16 which is a plan view of the drum base 15, three drum mounting surfaces 7'provided on the drum base 15 are coaxial with the screw holes 16. It is formed in an annular shape. When the surface accuracy of the drum mounting surface 7'is low, the drum bottom surface 6 and the drum mounting surface 7'are not in close contact with each other, and the drum bottom surface contacts only at the highest point in the drum mounting surface. Therefore, the drum may be obliquely attached to a predetermined plane formed by the three drum mounting surfaces. Further, when the screw 5 for fixing the drum is tightened in this state, the torque generated between the distance between the contact point and each screw is applied to the drum, and the drum is deformed. In particular, when the surface accuracy in the center direction of the drum is low, it has a great influence on the mounting posture of the drum. That is, with respect to the drum center direction indicated by the arrow H, the drum mounting surface 7 '
17A and 17B, a force in the direction of the arrow is applied to the drum 4 to cause the mounting failure of the drum 4 on the drum base 15 and the deformation of the drum. Become. In particular, since the tape device accelerates high-density recording with narrow tracks, ensuring track linearity is an important issue. Therefore, the drum mounting surface is required to have high flatness, which leads to an increase in cost during processing.

[0012]

SUMMARY OF THE INVENTION Therefore, according to the present invention, in the mounting structure of the drum base and the drum of the recording / reproducing apparatus, even if the drum mounting surface is not required to have the flatness as in the conventional case, the mounting surface is not supported. The purpose of the present invention is to provide a shape for the drum mounting surface that secures and holds the drum in a stable manner and further reduces the force applied to the drum by the tightening force of the screw to prevent the deformation of the drum and ensure the linearity of the lead. To do.

[0013]

In order to achieve the above object, the present invention provides a drum 4 comprising a rotary drum carrying a head 1 and a fixed drum 8 having a lead 3 for guiding the lower end of a tape 2. In a recording / reproducing apparatus of a system in which a tape 2 drawn from a tape cassette is wound at a predetermined angle, and the head 1 scans the tape 2 on the outer peripheral surface of the drum 4 to record and reproduce a signal. has a drum positioning and fixing means (drum base) 15 for positioning and fixing the drum 4 at a predetermined posture on the substrate, the positioning and fixing means 15, the drum solid
An opening 16 for passing a fixed screw, and the opening 16
Multiple drums placed near the bottom of the drum
And the center of the mounting surface 7 of each drum is
The distance from the center of the drum 4 to the center of the opening
Is disposed in a direction away from the center side of the drum than,
Distance L1 from the drum during heart side of the inner edge sides 71 of the drum mounting surface 7 to the outer edge side 72 on the opposite side of the drum center
Is smaller than the inner diameter d of the fixing opening 16.

Further, the drum mounting surface 7 has the inner edge.
The distance L1 from the side 71 to the outer edge 72 and the opening
Opening center line F drawn in the drum circumferential direction at the center of the part ?
The distance L2 to et the inner side 71, the relationship between the inner diameter d of the front KiHiraki opening 16,

L1 + L2 <(d / 2)

(However, for L2, the inner edge is closer to the center of the opening.
If it is arranged on the drum center side, it is assumed to be a negative value) .

[0017]

[Function] The depth of the drum mounting surface is made smaller than the diameter of the screw hole, and the drum mounting surface is offset by a predetermined amount on the outer peripheral side. Further, the drum mounting surface is formed into a straight line connecting the center of the drum and the screw. By arranging the drums on both sides of the screw in a direction at a right angle, that is, along the circumferential direction of the drum, the drum is not attached obliquely to the other mounting surface or the direction of the screw, and the predetermined position on the drum base is maintained. It is stably placed on the placing surface of. Further, even when the bottom surface of the drum comes into contact only at the highest point on the drum mounting surface, since the distance between the contact point and the screw is small, the above torque is hardly applied to the drum and the deformation of the drum does not occur. Further, since the drum mounting surface is arranged on both sides of the screw hole, the posture change of the drum due to the screw tightening does not occur. Furthermore, because the drum mounting surface is offset by a predetermined amount from the center line of the screw hole to the outer peripheral side, the bottom surface of the drum securely contacts the other drum mounting surface by tightening the screw, and the drum floats above the drum mounting surface. Can be eliminated.

[0018]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a perspective view showing the shape of a drum base 15 having a drum mounting surface 7 according to the first embodiment of the present invention. In the present invention, the depth of the drum mounting surface 7 is less than or equal to the inner diameter of the screw hole 16 for fixing the drum. Further, the drum mounting surface 7 is arranged with the screw hole 16 interposed therebetween in a direction substantially perpendicular to a straight line connecting the center of the drum 4 and the screw hole 16, that is, a direction along the outer peripheral surface of the drum 4.

FIG. 2 shows the drum mounting surface 7 in this embodiment.
It is sectional drawing which shows the state of the vicinity of the screw 5 which is fixing the drum 4 to the drum base 15 which has. Drum mounting surface 7
When the processing accuracy of is decreased, the protrusion 17 is formed on the drum mounting surface 7. However, since the depth L1 of the drum mounting surface 7 is configured to be smaller than the outer diameter of the screw 5, the distance l between the central axis of the screw 5 and the protrusion 17 becomes small and the tightening force f
Even if is added, the torque for rotating the lower drum 8 in the direction of arrow E is small, and the lower drum 8 is hardly deformed.

When a torque due to the tightening force of another screw is applied, the lower drum 8 only tilts in the direction of arrow D or E in the drawing, and hardly tilts in the direction perpendicular to the paper surface of the drawing. This is because, as shown in FIG. 1, the drum mounting surface 7 is arranged in a straight line across the screw hole 16, and even if the drum mounting surface 7 is inclined in the direction of arrow D or E, the lower drum 8
This is because the torque applied to is small. Drum mounting surface 7
Are arranged so as to sandwich the screw 5 in a direction substantially perpendicular to a straight line connecting the center of the drum 4 and the screw 5, that is, a direction along the outer peripheral surface of the drum 4 (screw hole center line F). Therefore, in FIG. 2, when the lower drum 8 is tilted in the direction of the arrow D or the arrow E by the tightening force of another screw, the bottom surface 6 of the lower drum 8 is brought into contact with another drum mounting surface, and the drum 8
Is fixed at a predetermined height and inclination. At this time, the torque applied to the lower drum 8 is small, and the lower drum 8 is not deformed. From the above, the lead 3 provided on the lower drum 8
Are held in place and linearity is ensured.

FIG. 3 is a plan view showing an arrangement state in which the drum mounting surface 7 is offset by a predetermined amount to the side opposite to the drum (downward in the drawing) in the above embodiment of the present invention. The drum mounting surface 7 is arranged such that the center line G between the inner edge 71 and the outer edge 72 is displaced from the screw hole center line F on the side opposite to the drum. The depth L1 of the drum mounting surface 7 is smaller than the diameter d of the screw hole 16. Further, the drum mounting surface 7 is evenly arranged on both sides of the screw hole 16 along the screw hole center line (drum circumferential direction) F. Therefore, as shown in FIG. 4 which is an X-X cross section of FIG. 3, even when the drum 4 is tightened by the screw 5, the drum does not tilt in the arrow direction in the figure. In the case of this embodiment, the distance L2 is a negative value. Hereinafter, in the present invention, the value represented by (L1 × 1/2) + L2 is the offset amount of the drum mounting surface 7.

Therefore, in the case of the mounting surface shape shown in FIG. 3, the ratio of the drum bottom surface abutting the drum mounting surface 7 on the side opposite to the screw hole center line F is high, and the direction of the center of the drum 4 ( The drum tends to incline with respect to the direction of the arrow in FIG. Therefore, the center line G of the drum mounting surface is aligned with the center line F of the screw hole.
It is possible to more reliably mount the drum on another drum mounting surface (not shown) disposed on the drum center side as compared with the case where the drums are aligned.

As for the shape of the drum mounting surface of the present invention, the shape of the mounting portion is formed in advance by using a mold, and only the mounting surface of the drum is finished by milling, thereby making it possible to soften the processing machine. It is possible to easily deal with it only by changing the above, and it is possible to adopt the same processing method as the conventional processing process, and the processing fee will not increase.

FIG. 5 is a plan view showing an example of an arrangement in which the arrangement of the drum mounting surface 7 shown in FIG. 3 is further offset to the side opposite to the drum. In the present embodiment, the drum mounting surface 7 is arranged with the inner edge 71 of the drum mounting surface 7 substantially aligned with the screw hole center line F, and the value of the distance L2 is 0, and the drum The offset amount of the mounting surface 7 is (L1 × 1 /
2). According to this embodiment, the drum bottom surface comes into contact with the screw hole center line F mainly on the side opposite to the drum. Therefore, with respect to the arrangement of the drum mounting surface 7 in FIG. 3, the drum can be mounted on the other drum mounting surface more reliably.

FIG. 6 is a plan view showing an arrangement example in which the arrangement of the drum mounting surface 7 shown in FIG. 5 is further offset to the side opposite to the drum. This arrangement is an example in which the inner edge 71 of the drum mounting surface 7 is provided at a distance L2 from the screw hole center line F. In this case, since the drum mounting surface 7 is arranged only outside the screw hole center line F, the drum bottom surface 6 comes into contact with the screw hole center line F further outside and on the opposite drum side. Therefore, compared with the arrangement of the drum mounting surface 7 in FIG. 5, the drum can be mounted on the other drum mounting surface more reliably. According to the result of the examination under the general drum mounting condition, the track linearity can be well ensured by setting the offset amount from the screw hole center line F in the range of 0 to 0.4 mm.

FIG. 7 shows an example in which the drum 4 is screwed to a drum base 15 made of aluminum die casting with a torque of 0.5 kg.cm under general drum mounting conditions, that is, FIGS. 6 is a graph showing the relationship between the area of the drum mounting surface 7 shown in FIG. 6 and the deterioration amount of track linearity. From the figure, if the area A of the drum mounting surface 7 is too small, the drum mounting surface 7 is crushed by the compression force due to the mounting of the drum, and the plane formed by the three drum mounting surfaces 7 is a predetermined plane. Is not formed, and as a result, the drum is deformed and the linearity of the lead 3 is deteriorated. As a result, the linearity of the track 19 of the tape 2 deteriorates. Therefore, in the examination result under these conditions, the area A of the drum mounting surface 7 in which the deterioration amount of the track linearity does not exceed 1 μm is considered in consideration of the variation of the screw tightening torque.
Is preferably A ≧ 0.3 mm ² . That is,
The offset amount from the screw hole center line F is 0 to 0.4 mm, the drum placement surface depth is L1 <(d / 2) -L2, and the drum placement area A ≧ 0.3 mm ² It is desirable to set so that Specifically, L
If 1 is 0.4 mm and the width of the drum mounting surface is 0.4 mm, the sum of the areas of the two drum mounting surfaces 7 can be 0.32 mm ² .

As described above, according to this embodiment, the depth of the drum mounting surface is made smaller than 1/2 of the diameter of the screw hole, and the drum mounting surface is offset from the drum side by a predetermined amount. , By placing the drum mounting surface on both sides of the screw along a direction approximately perpendicular to the straight line connecting the center of the drum and the screw, that is, by arranging the drum on both sides of the screw along the circumferential direction of the drum With respect to the drum base, it is not obliquely attached, and the drum base is stably mounted on a predetermined mounting surface. Further, even if the bottom surface of the drum comes into contact only at the highest point on the drum mounting surface, the distance between the contact point and the screw is small, so that the torque is not applied to the drum and is not deformed.

Further, in the above embodiment, the case where three screws are used to fix the drum is shown. However, as shown in FIG. 8, the drum has two screws to form the screw holes 16 and 16 '. In the case of using and fixing the structure, one of the three drum mounting surfaces 7, 7 ′, 7 ″ arranged at the positions of the vertices of the substantially equilateral triangle has the structure shown in this embodiment. By
It is possible to obtain the same effect as that of the above-mentioned embodiment. Also,
The same effect can be expected when the drum is fixed to the drum base with one screw. Further, in the present embodiment, all three drum mounting surfaces 7 have the shape of the present invention, but the same effect can be obtained even if only one or two drum mounting surfaces have the shape of the present invention. it can. Further, in the above description, the example in which the drum positioning and fixing means (drum base) 15 is formed separately from the mechanism substrate (chassis) has been shown, but it goes without saying that the drum base may be integrally formed with the chassis. .

[0030]

According to the drum mounting surface of the present invention, the area of the drum mounting surface is reduced, and the installation location is offset from the center line of the screw hole to the outside. The lead is not deformed, and the drum is not attached at an inclination angle or an inclination direction different from a predetermined angle. As a result, the processing accuracy of the drum mounting surface can be made lower than before, and the processing cost of the drum mounting surface of the base can be reduced.

Further, in the assembling process for fixing the drum to the drum base, it is possible to improve the margin against variations in the tightening torque of the screws for fixing the drum.

[Brief description of drawings]

FIG. 1 is a perspective view showing the structure of a drum base according to the present invention.

FIG. 2 is a cross-sectional view showing a state near a drum mounting screw of a drum base according to the present invention.

FIG. 3 is a partial plan view showing a configuration of a mounting surface according to the present invention.

FIG. 4 is a cross-sectional view taken along line XX of a state in which the drum is screwed onto the drum mounting surface of FIG.

FIG. 5 is a plan view showing another configuration of the mounting surface according to the present invention.

FIG. 6 is a plan view showing still another configuration of the mounting surface according to the present invention.

FIG. 7 is a graph showing the relationship between the area of the drum mounting surface and the track linearity deterioration amount according to the present invention.

FIG. 8 is a perspective view showing still another configuration of the drum base according to the present invention.

FIG. 9 is a perspective view showing the concept of the structure of the drum of the recording / reproducing apparatus.

FIG. 10 is an explanatory diagram of a track pattern recorded by a recording device having a lead with good linearity.

FIG. 11 is an explanatory diagram of a track pattern recorded by a recording device having a lead whose linearity is deteriorated.

12 is a characteristic diagram showing read characteristics of the track pattern of FIG.

FIG. 13 is a characteristic diagram showing read characteristics of the track pattern of FIG.

FIG. 14 is a perspective view showing the shapes of a conventional drum base and a drum.

FIG. 15 is a cross-sectional view showing a state near a drum mounting screw of a conventional drum base.

FIG. 16 is a plan view showing the shape and arrangement of a drum mounting surface of a conventional drum base.

FIG. 17 is a side view showing a deformed state of a drum mounted on a drum base having a drum mounting surface with low processing surface accuracy.

[Explanation of symbols]

1 head 2 tapes 3 leads 4 drums 5 screws 6 Bottom of lower drum 7 Drum mounting surface 8 Lower drum 9 Upper drum 15 drum base 16 screw holes

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noriaki Masuda 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd., Visual Media Research Laboratory (72) Inventor Atsushi Inoue 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Company Hitachi, Ltd. Video Media Research Laboratory (72) Inventor Fukubira 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Video Media Research Laboratory (72) Inventor Nao Ichikawa 1410 Inada, Hitachinaka City, Ibaraki Hitachi, Ltd. Factory Personal Media Equipment Division (72) Inventor Masashi Ueda 1410 Inada, Hitachinaka City, Ibaraki Prefecture Hitachi Ltd. Personal Media Equipment Division (72) Inventor Yoshiharu Yamashita 1410 Inada, Hitachinaka City, Ibaraki Hitachi Persona Corporation Rumedia Equipment Division (72) Inventor Kazuyuki Kodama 1410 Inada, Hitachinaka City, Ibaraki Prefecture Hitachi, Ltd. Personal Media Equipment Division (56) Reference JP-A-6-20238 (JP, A) JP 2 -254663 (JP, A) JP 60-182087 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 15/61 G11B 33/12

Claims (2)

(57) [Claims] 1. A tape comprising a rotary drum having a head mounted thereon and a fixed drum having a lead for guiding a lower end of the tape is wound around a tape drawn from a tape cassette at a predetermined angle so that the head has an outer peripheral surface. In a recording / reproducing apparatus for recording and reproducing a signal by scanning the tape above, drum positioning fixing means for positioning and fixing the drum in a predetermined posture state is provided on a mechanism substrate, and the positioning fixing means is , For threading screws for fixing the drum
And the bottom of the drum provided near the opening
A plurality of drum mounting surfaces, and the centers of the respective drum mounting surfaces are all the drum centers.
Than the distance to et the aperture center is disposed in a direction away from the drum center side, opposite the outer edge side of the <br/> in drum heart from the drum center side of the inner edge side of the drum mounting surface recording and reproducing apparatus and wherein the distance L1 is smaller than the inner diameter d of the front KiHiraki opening up. 2. The drum mounting surface has a distance L1 from the inner edge to the outer edge and the opening.
From the opening center line drawn in the drum circumferential direction at the center of the part
The distance L2 to the inner side, before the relationship between the inner diameter d of KiHiraki opening portion, L1 + L2 <(d / 2) ( provided that L2 is inner sides drum center side from the aperture center
2. The recording / reproducing apparatus according to claim 1, wherein the recording / reproducing apparatus satisfies a relationship of ( a negative value is set in the case of being arranged) .