JPH0454629Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a magnetic tape cassette, and more particularly to the structure of a guide block held between upper and lower plates thereof.

2. Description of the Related Art Conventionally, magnetic tape cassettes have generally used a plastic case, for example, a two-piece case combining upper and lower halves molded from plastic. However, such plastic halves have rather complicated shapes, and their planes tend to curve in any direction due to thermal deformation or molding distortion of the plastic itself. Therefore, even when assembled into a case, the curvature remains. Problems such as poor running, track deviation, and phase deviation may occur. Therefore, in order to not only prevent the cassette case from curving and solve these problems, but also to improve the acoustic characteristics and increase the mechanical strength, some cassette cases have a three-piece structure. FIG. 2 is an exploded perspective view of the case of a magnetic tape cassette having such a three-piece structure.
In the figure, 10 is the upper plate, 12 is the middle frame, 1
4 is the lower plate. Upper and lower plates 10, 14
Both are rectangular, almost flat, and manufactured by injection molding of plastic. Although the middle frame 12 has a rectangular shape, it is a ring-shaped frame and is die-cast using metal such as zinc or aluminum. In this cassette case, these upper and lower plates 10 and 14 are connected to the middle frame 12.
The three pieces are assembled together by aligning them by sandwiching them from above and below, and screwing the four corners. Therefore, a tape storage section for storing a magnetic tape and a head insertion section for making contact between the magnetic tape and the head are formed in the case. middle frame 12
The inside of the ring covered by the upper and lower plates 10 and 14 is a tape storage space 16 that forms a tape storage section, and the inwardly recessed outside of the ring corresponding to the front side is a head insertion section that forms a head insertion section. There is a space 18. That is, the inwardly recessed side wall at the center of the front side forms the tape storage space 16 and the head insertion space 1.
8 and a partition wall 20. This partition wall 20 is bilaterally symmetrical, with a support hole 22 for screwing in the center, guide pin through holes 24, 24a, 24b for positioning the cassettes near the left and right front of the hole 22, and on both sides of each through hole 24. Central tape guide protrusions 26, 26a to 26d are arranged as if the door were opened on both sides. Side tape guide protrusions 28, 28a, and 28b are located near both ends of the side wall corresponding to the front side, at the corners of the head insertion space 18, and form slits through which the magnetic tape passes. That is, the magnetic tape stored in the tape storage section is inserted into the lateral tape guide protrusion 2 on the left side.
8a, passes through the slit there, enters the head insertion part, is guided by the four central tape guide protrusions 26, contacts the right side tape guide protrusion 28b, and passes through the slit there. , return to the tape storage area again. Or vice versa, follow the passage. At this time, the magnetic tape receives a pressing force from a pressure pad placed in front of the partition wall 20, and comes into contact with a magnetic head inserted from the tape recorder to perform recording and reproduction. The side wall of the middle frame 12 has no cut points other than the slit, and stands continuously upright.

However, in the case of such a magnetic tape cassette, the middle frame 12 is formed into a ring shape, a part of which is placed against the partition wall 20, and a large number of tape guide protrusions 26, 28, etc. are sequentially protruded from the middle frame 12, so that it can also be configured as a guide block. Therefore, the same unit has both a frame function and a tape guide function. The frame functions include increasing the mechanical strength and weight of the cassette case and preventing the case from bending. Note that as the weight of the cassette case increases, unnecessary resonance does not occur and the acoustic characteristics improve. Further, the tape guide function includes applying an appropriate amount of frictional force to the running magnetic tape from the contact surface of the tape guide portion to improve the shape and dimensional accuracy of that portion. In this way, the middle frame 12 is required to function as a frame and as a tape guide system, and the frame function is mainly performed by the three pieces of the middle frame 12 and both left and right ends of the front piece, and the tape guide function is mainly performed. The guide block, which is the partition wall 20 located in the center of the front piece, is in charge of this.

Problems that the invention aims to solve Based on this idea, even if a cassette is made in which the frame (some of which includes upper and lower plates) and the guide block are separated, if the guide block is not supported properly, perpendicularity of the tape guide to the cassette cannot be obtained. As a result, the tape may be tilted or run out of alignment, causing a phase shift or track shift.

The present invention was developed by focusing on these conventional problems, and by improving the support method of the guide block, it has excellent tape guide function, good running performance, and eliminates track deviation and phase deviation. An object of the present invention is to provide a magnetic tape cassette that does not generate modulation noise or the like.

Means for Solving the Problems Means for achieving the above object will be described below with reference to FIG. 1, which corresponds to an embodiment.

This magnetic tape cassette has a tape storage section for storing the magnetic tape and a head insertion section where the magnetic tape and the magnetic head come into contact. The cassette case has upper and lower plates 30 and 36, a tape storage section sandwiched between the upper and lower plates 30 and 36, and a head insertion section that is partitioned, and a plurality of magnetic tapes that guide the magnetic tape inside the head insertion section. an elongated independent guide block 3 having a tape guide 76 of
4. At this time, in order to sandwich the guide block 34 between the upper and lower plates 30 and 36, a hole 66 is provided in the center of the guide block 34 for positioning the running direction of the magnetic tape and the direction perpendicular to the surface of the magnetic tape.
are provided, and the upper and lower plates 30, 3 are inserted into the positioning holes 66.
The cylindrical body 82e protruding from either inner surface or both inner surfaces of 6 is fitted into the positioning hole 66.
An opposing portion 83 in which two tape guide portions 76 located on both sides are provided on the inner surfaces of the upper and lower plates 30, 36.
Support each surface on each side that corresponds to the mold mating surface.

Effect The above means works as follows.

The cassette case includes upper and lower plates 30 and 36, and a plurality of tape guide sections that partition the tape storage section sandwiched between the upper and lower plates 30 and 36 from the head insertion section and guide the magnetic tape within the head insertion section. Elongated independent guide block 3 with 76
4, since the guide block 34 is an independent body, it can fully perform its tape guide function without considering other functions such as a frame function. Furthermore, in order to sandwich the guide block 34 between the upper and lower plates 30 and 36, a hole 66 is provided in the center of the guide block 34 for positioning the running direction of the magnetic tape and the direction perpendicular to the magnetic tape surface. hole 66
When a cylindrical body 82e protruding from either or both inner surfaces of the upper and lower plates 30, 36 is fitted, the magnetic tape The guide block 34 can be positioned by making the running direction of the magnetic tape correspond to its X axis and the direction perpendicular to the magnetic tape surface to its Y axis. In addition, since the two tape guide portions 76 are supported by respective surfaces that correspond to the mold mating surfaces of the opposed portions 83 provided on the inner surfaces of the upper and lower plates 30 and 36, the tape guide portions 76 are supported in the direction perpendicular to the reference plane, that is, in the Z-axis direction. positioning can be performed with high precision. In this way, the guide block 34 is positioned at only three or two locations on the inner surface of each of the upper and lower plates 30, 36,
Only those parts are strongly supported locally from three directions, and most of them do not contact the inner surface,
A separation space is formed between the guide block 34 and the inner surfaces of the upper and lower plates 30, 36. Therefore, the guide block 34 does not come into even contact with the inner surfaces of the upper and lower plates 30 and 36, and is less susceptible to other unevenness on the inner surfaces, so that Perpendicularity is easily obtained. Therefore, the shape of the contact point with the magnetic tape,
Dimensional accuracy can be improved. When the tape guide portion 76 is not tilted and the magnetic head contacts the magnetic tape at an appropriate position, running performance is improved and no track deviation or phase deviation occurs. In addition, if a suitable material is selected for the guide block 34, an appropriate amount of frictional force is applied to the magnetic tape from the contact surface of the tape guide section 76, so that speed irregularities such as continuous slow speed repetitions do not occur in the tape running. Magnetic tape moves smoothly. As a result, it is possible to reduce the occurrence of modulation noise, which is a phenomenon in which sound becomes muddy due to frequency modulation.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

FIG. 1 is an exploded perspective view of a case of a magnetic tape cassette according to an embodiment of the present invention. Figure 3 shows
2 is a detailed view of the guide block shown in FIG. 1, in which figure A is a plan view and figure B is a front view. FIG. 4 shows a magnetic tape cassette according to an embodiment of the present invention, in which figure A is a plan view and figure B is a front view. In the figure, 30 is an upper plate, 32 is a side frame, 34 is a guide block, and 36 is a lower plate, such as a lower plate. The upper and lower plates 30, 36 are both rectangular and generally flat, and are molded from plastic, for example transparent plastic. The outer surface of the upper plate 30 and the outer surface of the lower plate 36 have approximately the same external dimensions as conventional standard products. side frame 32
is roughly rectangular in shape, but the center of one side corresponding to the front side is missing. This side frame 32 is a support frame manufactured by die-casting using metal and whose upper and lower surfaces are flat and parallel. Guide block 3
Reference numeral 4 denotes an elongated bow-shaped plastic molded product which is placed between the inner surfaces of the upper and lower plates 30 and 36 to close the missing portion of the side frame 32 from the inside.
When these four members such as the upper and lower plates 30, 36, the side frame 32, and the guide block 34 are aligned and assembled, the cassette case becomes a four-piece structure, with a tape storage section for storing the magnetic tape inside, and a tape storage section for storing the magnetic tape. A head insertion portion is formed which makes contact with the head. Reference numerals 38, 38a, and 38b are a pair of holes into which the hub drive shafts are inserted, located at symmetrical positions in the center of the upper plate 30. The entrance edges of these holes are tapered. Reference numeral 40 denotes a trapezoidal protrusion protruding near the center of the front surface of the upper plate 30, the outer surface of which serves as a reference surface for manufacturing the cassette case. There are screw holes 42, 42a to 42e near the center of the trapezoidal protrusion 40 and at the four corners of the upper plate 30 for combining with the other three members. Further, the trapezoidal protrusion 40 has guide pin insertion holes 44, 44a, 44b for cassette positioning which also serve as alignment means during assembly, and capstan insertion holes 46, 46a, 46b. There is an opening 50 for associating the magnetic tape with a working member such as a head. The side frame 32 has left and right short sides 52, 54,
Consisting of a rear long side 56 and front sides 58, 58a, and 58b, the interior has a space 5 for storing a magnetic tape roll.
9, but the center part of the front side 58 is missing. All their sides extend in the same upper and lower parallel planes. There are recesses 58, 58a, 58b for preventing erroneous recording and erasure on the outer surface of the rear long side 56 near both ends, and symmetrical arc-shaped recesses 60, 60a, 60b along the rear long side 56 on the inner surface thereof. Further, at the corners of each side, there are through holes 62, 62a to 62d at positions corresponding to the screw holes 42 of the upper plate 30. The guide block 34 is arranged so that its central portion corresponds to the trapezoidal protrusion 40 of the upper plate 30, and its both ends extend to near the inner surfaces of the left and right short sides 52, 54 of the side frame 32. Close the defect from the inside. At this time, the trapezoidal protrusion of the lower plate 36 is also arranged in a similar manner. This guide block 34 serves as a partition wall between the tape storage section of the cassette case and the head insertion section, and is provided with tape guide means. Therefore, the arcuate recesses 64, 64a are located at symmetrical positions on the tape storage side.
64b are respectively formed, and a large number of tape guide sections, which will be described later, are arranged on the head insertion section side. Note that the arcuate recess 60 of the side frame 32
and the arcuate recess 64 of the guide block 34 define the outermost diameter of the magnetic tape roll. 6
Reference numeral 6 designates a through hole for positioning provided in a thick mountain-shaped portion at the center of the guide block 34. There is a pressure pad installation recess 68 in the front of the mountain-shaped thick part, and on both sides of the recess 68, there are a pair of upper and lower toric bodies 70, 70a, 70b, 72, 7, respectively.
2a and 72b are respectively provided. Through holes 73, 73 connecting the upper and lower parts of these toric bodies 70, 72
A guide pin for cassette positioning is inserted into a and 73b. These through holes 73 are reference holes, and by inserting the cassette positioning guide pin therein, the magnetic tape cassette is accurately positioned and mounted at a predetermined location on the tape recorder. Moreover, each torus 70,
On both sides of 72, there are central tape guide parts 74, 74a~ which guide the magnetic tape, as if the doors were opened on both sides.
Four 74d are formed. Each of these tape guide portions 74 has bifurcated clamping portions on the upper and lower sides, and a guide member such as a guide pin that directly contacts the magnetic tape is installed there. In this way, the guide member is connected to the guide block main body (guide block 3
4 (excluding the guide member), its material, dimensional accuracy, etc. can be selected and determined separately from the guide block body. Furthermore, if guide members having different frictional resistances are installed in the tape guide portions 74 provided on both sides of the through hole 73, which is the reference hole, the frictional resistance can be changed depending on the distance of the guide members 79, 77 relative to the head insertion position. Therefore, the frictional force applied to the magnetic tape can be selected to be appropriate depending on the positional relationship with the head. That is, the frictional resistance of the guide members 77, 77a, 77b located near the pressure pad 75 that presses the magnetic tape against the head is small, and the frictional resistance of the guide members 79, 79a, 79b located far away is set large. This is because near the head, the frictional force applied to the magnetic tape from the guide member 77 must be reduced to prevent uneven speed of the magnetic tape, while at a position far from the head, the frictional force applied from the guide member 79 is reduced. This is because the magnetic tape cannot be moved smoothly unless the force is increased. For this purpose, the guide member 7
For the guide member 79, a metal pin made of stainless steel, aluminum, etc. is used, and for the guide member 79, a plastic pin made of nylon, polyacetal, ABS, polystyrene, etc. is used. Ceramic pins can also be used instead of those pins. There are arc-shaped recesses for inserting the capstan on both sides of the central tape guide portion 74, and side tape guide protrusions 76, 76a, 76b are located near both ends. Slits through which the magnetic tape passes are formed between these side tape guide protrusions 76 and both ends of the side frame 32 (ends of the front side 58). A head insertion space 78 is defined by such side tape guide projections 76. 8
0, 80a, and 80b are end tape guide protrusions at both ends of the guide block 34, and these ends are fitted into through holes provided in the planes of the upper and lower plates 30, 36. Guide block 3 like this
4 has a positioning hole 66 at the center and a side tape guide projection 7 that defines a head insertion space 78 on the side.
6. Both ends are firmly supported by the upper and lower plates 30 and 36 with end tape guide protrusions 80 interposed therebetween.

Therefore, the guide block 34 is attached to the upper and lower plates 3.
The main support structure for clamping at 0.36 will be explained in detail next. First, the trapezoidal protrusion 4 of the upper and lower plates 30, 36 is placed in the center of the guide block 34.
For the X-axis and Y-axis on the reference plane such as 0,
The positioning holes 66 are provided so that the running direction of the magnetic tape corresponds to its X axis, and the direction perpendicular to the surface of the magnetic tape corresponds to its Y axis. Next, in the positioning hole 66, a cylindrical body protruding from either the inner surface or both inner surfaces of the upper and lower plates 30, 36, for example, a screw hole drilled near the center of the reference plane of the trapezoidal protrusion 40 of the upper plate 30. A cylindrical body protruding from the circumferential inner surface of 42e is fitted to couple them. Also, the two tape guide portions 76 located on both sides of the positioning hole 66 are connected to the upper and lower plates 30 and 3.
Support stands are provided at opposing portions of the inner corners of the trapezoidal protrusions 40 and the like corresponding to the reference planes of the trapezoidal protrusions 40 of No. 6, respectively, and support is provided on each of these surfaces. Then, positioning can be performed in the direction perpendicular to the reference plane, that is, in the Z-axis direction. In this way, the guide blocks 34 are installed at three or two locations on the inner surface of each of the upper and lower plates 30, 36.
Only those portions are positioned and only those portions are firmly supported in three directions, most of which do not contact the inner surface, and there are gaps between the guide block 34 and each of the upper and lower plates 30, 36 as shown in FIG. Isolated spaces 81, 81a, and 81b as shown are formed. Therefore, the guide block 34 is connected to each upper and lower plate 3.
0 and 36, and is less affected by other unevenness on the inner surface, it is easy to obtain perpendicularity to the reference plane of the tape guide portions 74, 76, 80, etc. Therefore, the shape and dimensional accuracy of the contact portion with the magnetic tape can be improved. In this way, the tape guide section 7
If the magnetic heads 4, 76, and 80 are not tilted and the magnetic head contacts the magnetic tape at an appropriate position, running performance is improved and no track deviation or phase deviation occurs. In addition, if a material suitable for the guide block 34 is selected, the tape guide portion 7 can be moved against the magnetic tape.
Since an appropriate amount of frictional force is applied from the contact surfaces such as 4, 76, and 80, the magnetic tape moves smoothly without causing speed irregularities such as repeated slow speeds during tape running. Therefore, naturally, modulation noise, which is a phenomenon in which the sound becomes muddy due to frequency modulation, does not occur. Since the guide block 34 is an independent body in this way, it can fully perform the tape guide function without considering other functions such as the frame function.

The lower plate 36 is substantially vertically symmetrical to the upper plate 30. A cylindrical body 8 is provided around the screw holes in the four corners and the trapezoidal protrusion from the upper plate 30.
2, 82a to 82e protrude longer. This is the side frame 32 and guide block 34
It fits into corresponding through-holes 62 and 66 provided in the holes 62 and 66 to provide guidance and alignment when assembling them, and to firmly connect them. 83,8
Reference numerals 3a and 83b are support stands that support the lower surface of the tape guide portion 76 described above, and by aligning their upper surfaces with the mold mating surfaces, positioning accuracy in the Z-axis direction can be easily increased. Note that similar supports are also provided at corresponding positions on the upper plate 30. Further, 84 is a pedestal portion that almost covers and occupies the inner surface of the lower plate 36, and a similar one is also present in the upper plate 30. Further, a similar hole penetrates through the upper plate 30 at a position corresponding to the hub drive shaft insertion hole 38, and the annular collar 86,
86a and 86b, into which a hub around which a magnetic tape is wound is loosely fitted. Note that a similar annular collar is also present on the upper plate 30. Further, the structure of the trapezoidal protrusion is substantially the same as that of the upper plate 30 both inside and outside.

In this way, since the side frame 32 and the guide block 34 are separate bodies, the side frame 32
By selecting and using the most suitable material for the cassette case, it is possible to satisfy the frame function, and at the same time increase the mechanical strength and weight of the cassette case, thereby preventing the case from bending. Therefore, for example, it is preferable to use metal such as zinc or aluminum for the side frame 32 and plastic such as polyacetal, nylon, polystyrene, or ABS for the guide block 34.

Next, the above-mentioned upper and lower plates 30, 36, side frame 32, and guide block 34 are aligned, and the side frame 32 and guide block 34 are sandwiched between the upper and lower plates 30, 36, and the predetermined four
When the case is assembled by screwing together the five corners and the center near the front, the tape storage section 86 has a supply side hub 90 around which a magnetic tape 88 is wound and a take-up side hub 92 at symmetrical positions. Delivered and installed. Further, a pressure pad 75 is delivered and installed in the center of the head insertion portion 94. When recording, the supply side hub 9
The magnetic tape 88, which is sent out sequentially from 0, has an end tape guide protrusion 80a and a guide roller 98 from the left.
a, passes through the side tape guide protrusion 76a, passes through the slit 100a there, and enters the head insertion portion 94. Further, it is guided by the central tape guide parts 74a and 74b on the right side, receives the pressing force of the pressure pad 75 at the center of the head insertion part 94, and comes into contact there with a magnetic head (not shown) inserted from the tape recorder. Next, the magnetic tape 88 is guided by similar tape guide portions 74c, 74d, 76a, 80b, slit 100b, guide roller 98b, etc. located at symmetrical positions on the right, and is sequentially wound onto the winding hub 92. go. During reproduction, the magnetic tape 88 is once rewound to the supply hub 90 and follows the same path as during recording.

In addition, in this embodiment, independent guide blocks are used together with the upper and lower plates and the side frames.
Although the cassette case has been constructed with a body structure, it is also possible to construct a cassette case with a three-body structure by using the upper and lower halves, which are upper and lower plates.

Effects of the invention According to the invention described above, the cassette case is equipped with an elongated independent guide block having a plurality of tape guide parts, and since the guide block is held between the upper and lower plates, the magnetic tape is placed in the center of the guide block. A hole is provided for positioning the running direction and a direction perpendicular to the magnetic tape surface, a cylindrical body protruding from either or both inner surfaces of the upper and lower plates is fitted into the positioning hole, and the positioning hole is further provided. The two tape guide parts located on both sides of the guide block are supported by the opposing surfaces provided on the inner surfaces of the upper and lower plates that correspond to the mold mating surfaces, allowing accurate positioning of the guide block in three directions. Therefore, the tape guide function can be improved. Therefore, running performance is good, and track deviation, phase deviation,
It is possible to reduce the occurrence of modulation noise and the like.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of a case of a magnetic tape cassette according to an embodiment of the present invention. Figure 2 shows
FIG. 2 is an exploded perspective view of a case of a conventional magnetic tape cassette. FIG. 3 is a detailed view of the guide block shown in FIG. 1, in which figure A is a plan view and figure B is a front view. FIG. 4 shows a magnetic tape cassette according to an embodiment of the present invention, in which figure A is a plan view and figure B is a front view. 30, 36... Upper and lower plates, 32... Side frame, 34... Guide block, 66... Positioning hole, 74, 76, 80... Tape guide section, 75... Pressure pad, 77, 79...
Tape guide section, 81... isolated space, 82... cylindrical body, 83... opposing portion of the lower plate to the tape guide section 76, 86... tape storage section, 88
...Magnetic tape, 90, 92...Hub, 94...
Head insertion part.

Claims (1)

[Scope of utility model registration request] In a magnetic tape cassette having a tape storage section for storing a magnetic tape and a head insertion section where the magnetic tape and the magnetic head come into contact, the cassette case has upper and lower plates and is held between the upper and lower plates. It is equipped with a long and independent guide block that partitions the tape storage section and the head insertion section and has a plurality of tape guide sections that guide the magnetic tape inside the head insertion section. A hole is provided in the center of the magnetic tape for positioning the running direction of the magnetic tape and the direction perpendicular to the magnetic tape surface, and a cylindrical body protruding from either the inner surface or both inner surfaces of the upper and lower plates is fitted into the positioning hole. A magnetic tape cassette characterized in that two tape guide portions located on both sides of the positioning hole are supported by respective surfaces corresponding to mold mating surfaces of opposing portions provided on the inner surfaces of the upper and lower plates. .