JP3560207B2 - Magnetic tape cassette - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a magnetic tape cassette used for a magnetic recording / reproducing device such as a video tape recorder and other various information processing devices, and more particularly, an opening / closing lid that covers an opening on the front surface of the cassette body so as to be freely opened and closed, The present invention relates to a magnetic tape cassette of a type including three lids.
[0002]
[Prior art]
2. Description of the Related Art In recent years, magnetic tape cassettes and video tape recorders (hereinafter, referred to as VTRs) have become compact with the increase in density of magnetic recording. As a result, VTRs have been increasingly used outdoors, such as for taking pictures of landscapes and people. In view of the fact that the magnetic tape cassette is particularly intended for outdoor use, an open / close lid comprising two or three lids respectively covering the front and back surfaces of the tape has been put into practical use as a measure against dust.
[0003]
FIGS. 3 and 4 show a conventional example of a magnetic tape cassette in which an opening / closing lid that covers an opening on the front surface of the cassette body is composed of three lids.
The magnetic tape cassette 20 includes a cassette main body 24 having a front surface formed with an opening 22 for inserting a tape pull-out member on the device side such as a VTR, an upper cassette half 24a and a lower cassette half 24b constituting the cassette main body 24, A pair of reels 23 and 25 rotatably arranged in the lower cassette half 24b, and a tape guide wound around the two reels 23 and 25 and provided on the front surface of the lower cassette half 24b, the opening 22 is provided. And an opening / closing lid 27 attached to the front side of the cassette main body 24 so as to cover the magnetic tape 5 stretched in the opening 22 when carrying the portable device or the like. It has a configuration. Various components other than the reels 23 and 25 around which the magnetic tape 5 is wound are housed between the upper and lower cassette halves 24a and 24b, but these housing parts are omitted in FIG. .
[0004]
The opening / closing lid 27 includes three lids, an outer lid 29, a top lid 30, and an inner lid 31.
The outer lid 29 includes a front cover plate 29a that covers the front side of the magnetic tape 5 stretched over the opening 22, and side plate portions 29b that protrude from both sides of the front cover plate 29a. A support pin 29c is protruded from the inner wall surface of the side plate portion 29b, and the support pin 29c is rotatably fitted into the pin support holes 32 on both side portions near the front surface of the upper cassette half 24a. Supported. Accordingly, the outer lid 29 is rotatable about the support pin 29c.
[0005]
The top lid 30 includes an upper lid plate 30a that covers the upper portion of the magnetic tape 5 stretched over the opening 22, and both ends on the front edge side of the upper lid plate 30a are pivoted to the upper edge of the front lid plate 29a. The front lid connecting portion 30b is connected freely and the upper lid guide groove 33 formed on both side surfaces of the upper cassette half 24a protruding from the arm portion 30c extending from the rear edge of the upper lid plate 30a. And an upper lid slide pin 30d movably engaged. The front lid connecting portion 30b is a pin that fits into a locking hole 29d formed at both ends of the upper edge of the front lid plate 29a.
[0006]
When the top lid 30 is opened, the upper lid slide pin 30d moves along the upper lid guide groove 33 along with the pivotal movement of the front lid connecting portion 30b around the support pin 29c, and the cassette It moves to the rear end side of the cassette main body 24 substantially in parallel with the upper surface of the main body 24.
The inner lid 31 covers an inner lid plate 31a that covers the rear surface of the magnetic tape 5 stretched over the opening 22, and an upper edge of the inner lid plate 31a is rotatably connected to the upper lid plate 30a. An upper lid connecting portion 31b and an inner lid slide pin 31c that protrudes from both lower end portions of the inner lid plate 31a and slidably engages with an inner lid guide groove 35 formed on the inner side surface of the cassette body 24. Have. As shown in FIG. 4, the upper cover connecting portion 31b is a pin rotatably connected to a support piece 30e protruding from the upper cover plate 30a.
[0007]
When the outer lid 29 is opened, the upper lid connecting portion 31b follows the movement of the top lid 30. With the movement of the upper lid connecting portion 31b, the inner lid slide pin 31c moves the inner lid guide groove. Move on 35. That is, the inner lid 31 retreats above the opening 22 following the opening operation of the top lid 30.
[0008]
When the above-described magnetic tape cassette 20 is loaded into the VTR device, the side plate portion 29b of the outer lid 29 is pushed upward by a cover pin (not shown) provided on the VTR device side, and the outer lid 29 at that time is opened. In conjunction with the lid operation, the top lid 30 and the inner lid 31 perform the lid opening operation. When taking out the magnetic tape cassette 20 from the VTR device, the respective lids perform a lid closing operation, contrary to the loading operation.
[0009]
[Problems to be solved by the invention]
Incidentally, in the magnetic tape cassette 20 as described above, the movement trajectory of the top lid 30 is defined by the upper lid guide groove 33, but the sliding surfaces 33a and 33b of the upper lid guide groove 33 and the upper lid A frictional force is generated between the slide pin 30d and the slide pin 30d.
[0010]
Therefore, depending on the size and shape of the sliding surfaces 33a and 33b and the upper lid slide pin 30d, the smooth sliding of the upper lid slide pin 30d due to the opening and closing operation of the outer lid 29 may be hindered. May be difficult to open. For example, a force having a certain direction from the front lid connecting portion 30b through the upper lid slide pin 30d, that is, a force having a so-called pressure angle θ acts on the sliding surface 33a with which the upper lid slide pin 30d is in sliding contact. However, if the value of the pressure angle θ exceeds a certain range, smooth sliding of the upper lid slide pin 30d is hindered, and as a result, the opening / closing lid 27 becomes difficult to open.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above problems and to provide a good magnetic tape cassette that can smoothly open and close an openable lid.
[0011]
[Means for Solving the Problems]
The object of the present invention is to provide a pair of reels rotatably mounted by winding a magnetic tape in a cassette main body, and an opening / closing lid mounted to cover an opening on the front surface of the cassette main body so as to be openable / closable. In the provided magnetic tape cassette,
A front cover plate that covers the front side of the magnetic tape stretched over the opening, and a side plate portion that protrudes from both sides of the front cover plate that is pivotally supported on both side surfaces near the front surface of the cassette body; An outer lid provided with an upper lid plate that covers above the magnetic tape stretched over the opening, and both ends on the front edge side of the upper lid plate before being rotatably connected to the upper edge of the front lid plate. A lid connecting portion and an upper lid slide pin projecting from an arm portion extending from a rear edge of the upper lid plate and slidingly engaging with an upper lid guide groove formed on both side surfaces of the cassette body. A top lid, an inner lid plate covering the rear surface side of the magnetic tape stretched over the opening, an upper lid connecting portion rotatably connecting an upper edge of the inner lid plate to the upper lid plate, and the inner lid plate Inner cover guide formed on the inner side of the cassette Is constituted by an inner lid having a lid slide pin inner slidably engage the groove,
The upper lid slide pin of the top lid has a cross-sectional shape of at least a portion that slides on the sliding surface of the upper lid guide groove, and a normal line inclined forward in the moving direction from a normal line of the sliding surface at the contact point. This is achieved by a magnetic tape cassette characterized by being formed as a free curve.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a magnetic tape cassette according to an embodiment of the present invention will be described in detail with reference to the drawings. The same components as those of the conventional magnetic tape cassette shown in FIG. 3 are denoted by the same reference numerals, and detailed description is omitted.
FIGS. 1 and 2 are a side sectional view and an enlarged view of a main part of a front part of a magnetic tape cassette 1 according to an embodiment of the present invention. An opening / closing lid 10 composed of three lids, a lid 3 and an inner lid 31, is attached to be openable and closable.
[0013]
The outer lid 29, which covers the front surface of the magnetic tape 5 (not shown) exposed at the front of the cassette main body 24, allows the support pin 29c to rotate freely into the pin support holes 32 on both side portions near the front surface of the upper cassette half 24a. And is rotatable around the support pin 29c.
The top lid 3 includes an upper lid plate 3a that covers an upper part of the magnetic tape 5, and a front lid connecting portion that rotatably connects both ends on the front edge side of the upper lid plate 3a to the upper edge of the front lid plate 29a. 3b and an upper cover slide protruding from an arm 3c extending from the rear edge of the upper cover plate 3a and slidably engaging with upper cover guide grooves 33 formed on both side surfaces of the upper cassette half 24a. And a pin 3d. The front cover connecting portion 3b is a pin that fits into a locking hole 29d formed at both ends of the upper edge of the front cover plate 29a.
[0014]
When the outer lid 29 is opened, the top lid slide pin 3d moves along the upper lid guide groove 33 with the turning movement of the front lid connecting portion 3b around the support pin 29c. , And moves to the rear end side of the cassette body 24 substantially in parallel with the upper surface of the cassette body 24.
Further, according to the magnetic tape cassette 1 of the present embodiment, the upper lid slide pin 3d of the top lid 3 has a cross-sectional shape of a portion which is in sliding contact with the sliding surfaces 33a and 33b of the guide groove 33 at the contact point. The sliding surfaces 33a and 33b are configured to be in sliding contact with each other via curved surfaces 3e and 3f formed as free curves having normals inclined forward in the moving direction from the normals of the sliding surfaces 33a and 33b.
[0015]
Specifically, as shown by a two-dot chain line in FIG. 2, the conventional upper lid slide pin 30d has a circular cross section, but the upper lid slide pin 3d according to the present invention has a cross section having the free curve. The pin has a normal line Y inclined forward in the moving direction from a normal line X formed by the sliding surface 33a and the conventional slide pin 30d having a circular cross section. When the side plate portion 29b of the outer lid 29 is pushed upward by a lid-opening pin (not shown) in the opening / closing lid 10 in the final closed state as shown in FIGS. The front lid connecting portion 3b of the top lid 3 also turns around the support pin 29c.
[0016]
At this time, a force having a certain angle geometrically determined from the center of the front lid connecting portion 3b, that is, a force with respect to a point A of the sliding surface 33a with which the upper lid slide pin 3d of the top lid 3 contacts, so-called, A force (F) having a pressure angle θ acts, and the force (F) has an angle (α) with respect to a normal line Y of the upper lid slide pin 3d.
Therefore, the vertical effect component at point A of the sliding surface 33a is (F _N ), the static friction coefficient is (μ), and the force for sliding the upper lid slide pin 3d along the sliding surface 33a in the opening direction is shown. If (F _H ), the upper lid slide pin 3d slides in the lid opening direction along the sliding surface 33a when (F _H ) becomes larger than the frictional force (μF _N ) serving as the sliding resistance.
[0017]
Therefore, F _H > μF _N ,
F _H = F · sin (α),
F _N = F · cos (α),
From the equations, it can be understood that when μ <tan (α), the upper lid slide pin 3d slides in the lid opening direction along the sliding surface 33a.
[0018]
On the other hand, since the conventional upper lid slide pin 30d has a circular cross section, the normal line at the contact point of the sliding surface 33a coincides with the normal line X of the sliding surface 33a. Therefore, the force (F) acting on point A of the sliding surface 33a with which the upper lid slide pin 30d contacts has an angle (β) with respect to the normal X of the upper lid slide pin 30d. . Therefore, it can be seen that the upper cover slide pin 30d slides in the cover opening direction along the sliding surface 33a when μ <tan (β).
[0019]
That is, the angle (α) of the force (F) of the upper lid slide pin 3d with respect to the normal Y in the present embodiment is larger than the angle (β) of the force (F) with respect to the normal X of the conventional upper lid slide pin 30d. . Therefore, the vertical effect component F _N = F · cos (α) is a value smaller than the vertical effect component F _N = F · cos (β) when the conventional upper lid slide pin 30d having a circular cross section is used. Therefore, the upper lid slide pin 3d slides more easily than the conventional upper lid slide pin 30d.
Note that, in the present invention, the angle of the angle (α) itself may be appropriately set according to the size, material, and the like of the slide pin.
[0020]
Thus, the upper lid slide pin 3d is a pin having an elliptical cross-section, and slides through a curved surface 3e having a normal Y inclined forward in the moving direction from the normal X of the slide surface 33a. When the pressure angle θ of the force (F) is increased, the upper lid slide pin 3d can slide more smoothly than when the conventional upper lid slide pin 30d having a circular cross section is used. Therefore, the lid 10 can be opened smoothly.
[0021]
Further, when closing the opening / closing lid 10, the upper lid slide pin 3d is in sliding contact with the sliding surface 33b of the guide groove 33, but the upper lid slide pin 3d is higher than the normal line of the sliding surface 33b. The sliding surface 33b comes into sliding contact with the sliding surface 33b via a curved surface 3f having a normal line inclined forward in the moving direction. Therefore, the upper lid slide pin 3d can slide smoothly as in the case of opening the lid, and the lid 10 can be closed smoothly.
[0022]
In the above embodiment, a pin having an elliptical cross section has been described as an example of the upper lid slide pin 3d having a free curved cross section. However, the present invention is not limited to this. As a free curve, the slide pin has at least a cross section of a portion of the upper lid guide groove that is in sliding contact with the sliding surface having a normal line inclined forward in the moving direction from the normal line of the sliding surface at the contact point. The free curve is not limited to a curve along the peripheral surface of the pin having an elliptical cross section, and may take various curved shapes. It goes without saying that the shape of the upper lid slide pin which does not slide on the sliding surface of the upper lid guide groove may be any shape.
[0023]
【The invention's effect】
As described above, according to the magnetic tape cassette of the present invention, the upper lid slide pin of the top lid has a cross-sectional shape of a portion that is in sliding contact with the slide surface of the upper lid guide groove. The front lid connecting portion and the upper lid via the upper lid slide pin, because the upper lid slide pins are formed so as to be in sliding contact with each other via a curved surface formed as a free curve having a normal inclined forward in the moving direction from the line. Even when the pressure angle of the force acting between the sliding surface of the guide groove and the sliding surface of the guide groove becomes large, the upper lid slide pin can slide smoothly, and the open / close lid can be smoothly opened and closed. A tape cassette can be provided.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a front configuration of a magnetic tape cassette according to an embodiment of the present invention.
FIG. 2 is an enlarged view of a main part of the magnetic tape cassette shown in FIG.
FIG. 3 is an exploded perspective view showing a relationship between an opening / closing lid and a cassette main body in a conventional magnetic tape cassette.
FIG. 4 is a side sectional view showing a front configuration of the magnetic tape cassette shown in FIG. 3;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Magnetic tape cassette 3 Top lid 3d Top lid slide pin 3e Curved surface 3f Curved surface 5 Magnetic tape 29 Outer lid 31 Inner lid 33 Guide groove 33a Sliding surface 33b Sliding surface

Claims (1)

In a magnetic tape cassette including a pair of reels rotatably mounted by winding a magnetic tape in a cassette main body, and an opening / closing lid mounted to openably open an opening on the front surface of the cassette main body,
A front cover plate that covers the front side of the magnetic tape stretched over the opening, and a side plate portion that protrudes from both sides of the front cover plate that is pivotally supported on both side surfaces near the front surface of the cassette body; An outer lid provided with an upper lid plate that covers above the magnetic tape stretched over the opening, and both ends on the front edge side of the upper lid plate before being rotatably connected to the upper edge of the front lid plate. A lid connecting portion and an upper lid slide pin projecting from an arm portion extending from a rear edge of the upper lid plate and slidingly engaging with an upper lid guide groove formed on both side surfaces of the cassette body. A top lid, an inner lid plate covering the rear surface side of the magnetic tape stretched over the opening, an upper lid connecting portion rotatably connecting an upper edge of the inner lid plate to the upper lid plate, and the inner lid plate Inner cover guide formed on the inner side of the cassette Is constituted by an inner lid having a lid slide pin inner slidably engage the groove,
The upper lid slide pin of the top lid has a cross-sectional shape of at least a portion that slides on the sliding surface of the upper lid guide groove, and a normal line inclined forward in the moving direction from a normal line of the sliding surface at the contact point. A magnetic tape cassette characterized in that it is formed as a free curve.

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