JP2000311465A - Magnetic tape cassette - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic tape cassette which is easily assembled, can improve the productivity, and has an upper lid cam groove with sufficient strength. SOLUTION: An upper cam groove 36 is formed on both flank parts of an upper cassette half 35 for guiding an upper lid slide pin 10d projected inside the side plate of a top lid 10. The upper lid cam groove 36 has an open part 38 which is opened toward the front of the upper cassette half. The cam groove ceiling part 38a and cam groove bottom part 38b of the open part 38 are set at vertically the same positions and the distance X between the cam groove ceiling part 38a and cam groove bottom part 38b of the open part 38 is larger than the diameter D of the upper slide pin 10d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape cassette having upper and lower cassette halves and an opening / closing lid, and more particularly to a magnetic tape cassette characterized by the shape of an upper lid cam groove into which an upper lid sliding pin for a top lid is inserted. It relates to a tape cassette.

[0002]

2. Description of the Related Art Along with recent technical innovations due to a higher density of a magnetic recording medium, magnetic tape cassettes, video tape recorders (hereinafter, referred to as "VTRs") and the like have become smaller. As a result, VTRs are very often used outdoors, such as when shooting landscapes or people.

For this reason, in consideration of outdoor use and the like, a two- or three-sheet type lid for covering the front and back surfaces of the magnetic tape has been put into practical use as a measure against dust and dirt in consideration of outdoor use and the like.

FIGS. 9 to 12 show a conventional example of a magnetic tape cassette for a DVC (digital video cassette) in which an opening / closing cover for covering an opening on the front surface of the cassette body is constituted by three lids. is there.

This magnetic tape cassette 1 has a VT
A cassette main body 4 having an opening 2 for inserting a tape pull-out member on the device side such as an R, a magnetic tape 5 stretched over the opening 2 by a tape guide provided on the front surface of the cassette main body 4, The opening and closing lid 7 is attached to the front side of the cassette body 4 so as to cover the magnetic tape 5 stretched over the opening 2.

The cassette body 4 includes an upper cassette half 4a.
And the lower cassette half 4b. The opening / closing lid 7 includes three lids, an outer lid (front lid) 9, a top lid (upper lid) 10, and an inner lid (rear lid) 11.

The outer lid 9 includes a front cover plate 9a for covering the front side of the magnetic tape 5 stretched over the opening 2, and a front cover plate 9a.
a and side plate portions 9b projecting from both sides. A support pin 9c protrudes from an inner wall surface of the side plate portion 9b, and the support pin 9c is rotatably fitted and supported in pin support holes on both side surfaces near the front surface of the upper cassette half 4a. . The pin support hole has an inwardly expanding shape with a narrow entrance so that the pivot pin 9c does not come off. And
The outer lid 9 is rotatable about a pivot pin 9c.

The top lid 10 includes an upper cover plate 10a for covering the magnetic tape 5 stretched over the opening 2 and an upper cover plate 1a.
A front lid connecting portion 10b that rotatably connects both ends of the front edge side of the front lid 0a to an upper edge of the front lid plate 9a, and protrudes inside a side plate portion 10c extending from a rear edge of the upper lid plate 10a. Upper lid cam groove 13 formed on both side plates of upper cassette half 4a
And an upper lid sliding pin 10d slidably engaged with the upper cover.

When the outer lid 9 is opened, the upper lid sliding pin 10d is moved to the upper lid cam groove 13 with the turning movement of the front lid connecting portion 10b about the support pin 9c.
Along with the cassette body 4 as shown in FIG.
Is moved to the rear end side of the cassette body 4 substantially in parallel with the upper surface of the cassette body 4.

The inner lid 11 includes an inner lid plate 11a for covering the rear side of the magnetic tape stretched over the opening, and an inner lid plate 1a.
An upper lid connecting portion 11b rotatably connecting an upper edge of the inner lid 11a to an upper edge plate 10a, and an inner lid cam groove 15 formed on an inner plate portion of the cassette body 4 protruding from both lower edge sides of the inner lid 11a. And an inner lid slide pin 11c that engages with the inner lid.

The inner lid 11 is provided with the outer lid 9.
When the lid is opened, the top lid 10 is moved to move the top lid 10.
1b follows, and the inner lid sliding pin 11c moves on the inner lid cam groove 15 with the movement of the upper lid connecting portion 11b. That is, as shown in FIG. 11, the inner lid 11 retreats above the opening 2 following the opening / closing operation of the top lid 10.

The magnetic tape cassette 1 as described above has a VT
When loaded into the R device, the side plate 9b of the outer lid 9 is opened and closed by an open / close pin (not shown) provided on the device side.
Are pushed upward, and the top lid 10 and the inner lid 11 perform the lid opening operation in conjunction with the opening / closing operation of the outer lid 9 at that time. In order to take out the magnetic tape cassette from the VTR device, each lid operates to close the lid, contrary to the loading operation.

FIG. 12 shows one step of a method of assembling the magnetic tape cassette 1 having such a three-lid type opening / closing lid 7. As shown in FIG. 12, the outer lid 9,
The top lid 10 and the inner lid 11 are temporarily assembled. The support pin 9 of the outer lid 9 is inserted into the pin support holes 12 on both sides of the upper cassette half 4a near the front.
c and the upper lid slide pin 10d of the top lid 10 is inserted into the upper lid cam groove 13 provided in the upper cassette half 4a, and the three lids 9, 10, 11 are assembled to the upper cassette half 4a. To Next, the upper cassette half 4a and the lower cassette half 4b are assembled by screwing.

[0014]

However, FIG.
As shown in the figure, the support pin 9c of the outer lid 9 is inserted into the pin support holes 12 on both side portions near the front surface of the upper cassette half 4a.
Is a movement in the horizontal direction, and the top lid 1 is inserted into the upper lid cam groove 13 formed in the upper cassette half 4a.
The upper lid sliding pin 10d is inserted into the upper lid cam groove 13
Since the insertion portions 13a and 13b are inclined, the movement is in the inclined direction. That is, during the assembly, since the movement in the horizontal direction and the inclination direction must be performed at the same time, the insertion into the upper lid cam groove 13 of the upper lid sliding pin 10d cannot be performed smoothly.
It is difficult to improve productivity. Although it is certain that the upper cover cam groove 13 can be inserted into the upper cover cam groove 13 without inserting the upper cover slide pin 10d from the horizontal direction, the assembling operation becomes complicated, and it is difficult to improve the productivity. Become.

In order to solve the above-mentioned problem, the present applicant has proposed an invention in which the cam groove bottom surface of the upper cover cam groove is extended horizontally to improve the assembling property.
No. 3,346,637. However,
The thickness of the extended portion was often thin, and the shape was easily damaged. In addition, because of the shape similar to the edge, it was a portion where burrs were easily generated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an upper cover cam groove which is easy to assemble, can improve productivity, and has sufficient strength. An object of the present invention is to provide a magnetic tape cassette.

[0017]

The above object of the present invention is achieved by the present invention. The magnetic tape cassette according to claim 1 guides a cassette body composed of upper and lower cassette halves, an opening / closing lid having an outer lid, a top lid, and an inner lid, and an upper lid sliding pin protruding from a side plate of the top lid. An upper cover cam groove provided on both side surfaces of the upper cassette half, wherein the upper cover cam groove has a cam groove ceiling of the open portion in a magnetic tape cassette having an open portion opened forward of the upper cassette half. The cam groove bottom and the cam groove bottom are set at the same position in the vertical direction, and the distance between the cam groove ceiling and the cam groove bottom of the open portion is equal to or greater than the diameter of the upper lid sliding pin. And

According to the magnetic tape cassette of the first aspect,
The opening of the cam groove ceiling and the bottom of the cam groove of the open portion are at the same position in the vertical direction, that is, the entrance of the upper cover cam groove is aligned with the insertion direction of the upper cover sliding pin, and the cam groove ceiling of the open portion and the cam Since the distance from the groove bottom is equal to or larger than the diameter of the upper lid sliding pin, the upper lid sliding pin is smoothly inserted into the upper lid cam groove by the horizontal movement. Therefore, the operation of inserting the upper lid sliding pin can be performed smoothly, and the cassette can be easily assembled.

The magnetic tape cassette according to claim 2 is
A cassette body comprising upper and lower cassette halves, an opening / closing lid having an outer lid, a top lid and an inner lid; and both side portions of the upper cassette half for guiding an upper lid sliding pin projecting inside a side plate of the top lid. And an upper lid cam groove provided in the, the upper lid cam groove,
In the magnetic tape cassette having an open portion opened in front of the upper cassette half, an end of a portion extending from the cam groove ceiling of the open portion has a curved surface, and the cam groove ceiling of the open portion has a curved surface. The distance from the bottom of the cam groove is not less than the diameter of the upper lid sliding pin.

According to the magnetic tape cassette of the second aspect,
The end of the part extending from the cam groove ceiling of the open part is a curved surface,
That is, the portion that first contacts when inserting the inner lid sliding pin is curved, and the distance between the cam groove ceiling and the cam groove bottom of the open portion is equal to or greater than the diameter of the upper lid sliding pin. Therefore, the upper lid sliding pin is smoothly inserted into the cam groove while being guided by the curved surface in the movement for horizontal movement.
Therefore, the operation of inserting the upper lid sliding pin can be performed smoothly, and the cassette can be easily assembled.

Further, the magnetic tape cassette of claim 3 is
A cassette body comprising upper and lower cassette halves, an opening / closing lid having an outer lid, a top lid and an inner lid; and both side portions of the upper cassette half for guiding an upper lid sliding pin projecting inside a side plate of the top lid. And an upper lid cam groove provided in the, the upper lid cam groove,
In the magnetic tape cassette having an open portion opened in front of the upper cassette half, a portion extending in a horizontal direction from a cam groove ceiling portion of the open portion is provided, and the cam groove ceiling portion of the open portion is provided. The distance from the bottom of the cam groove is not less than the diameter of the upper lid sliding pin.

According to the magnetic tape cassette of the third aspect,
The part that extends horizontally from the cam groove ceiling of the open part,
The movement direction when assembling the lid, that is, a movement parallel to the horizontal direction, and the distance between the cam groove ceiling portion and the cam groove bottom portion of the open portion is equal to or larger than the diameter of the upper lid sliding pin. By the movement, the upper cover sliding pin is smoothly inserted into the cam groove. Therefore, the operation of inserting the upper lid sliding pin can be performed smoothly, and the cassette can be easily assembled.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a side view showing the upper cassette half 35 of the magnetic tape cassette 30 according to the first embodiment of the present invention. The description of the same components as those of the conventional magnetic tape cassette is simplified or omitted.

As shown in FIG. 1, the magnetic tape cassette 3
0, an upper lid cam groove 36 is formed on both side surfaces of the upper cassette half 35. The upper cover cam groove 36 is provided with an opening 38 that opens toward the front of the upper cassette half 35. As a characteristic configuration of the present embodiment, the cam groove ceiling portion 38a and the cam groove bottom portion 38b of the opening portion 38 are set at the same position in the vertical direction as shown by a dashed line. That is, the cam groove ceiling portion 3 of the conventional open portion 38
By setting the position of the upper cover cam groove 3a in the insertion direction of the upper cover sliding pin 10d shown in FIG.
6 entrances will be aligned. In addition, a distance X between the cam groove ceiling 38a and the cam groove bottom 38b of the opening 38.
Is set to be equal to or larger than the diameter D of the upper lid sliding pin 10d.

Next, a method of assembling the magnetic tape cassette 30 having the three-sheet type opening / closing lid 7 of this embodiment will be described with reference to FIG. As shown in FIG. 2, the outer lid 9, the top lid 10, and the inner lid 11 are temporarily assembled in advance, as in the related art. Then, the support pin 9c of the outer lid is fitted into the pin support hole 37 of the both side plate portions near the front surface of the upper cassette half 35, and the top lid 10 is inserted into the upper lid cam groove 36 formed on both side plates of the upper cassette half 35. The upper lid sliding pin 10d is inserted, and the three lids 9, 10, 11 are assembled to the upper cassette half.

At this time, the cam groove ceiling portion 38a and the cam groove bottom portion 38b of the open portion 38 of the upper cassette half 35 are located at the same position in the vertical direction in the upper cover cam groove 36, while the cam groove ceiling portion of the open portion 38 is formed. Since the distance X between 38a and the cam groove bottom 38b is equal to or greater than the diameter D of the upper lid sliding pin, the movement of fitting the pivot pin 9c of the outer lid 9 into the pin support hole 37 of the upper cassette half 35 The movement of inserting the upper lid sliding pin 10d into the upper lid cam groove 36 of the upper cassette half 35 is a horizontal movement, and the positions at which the upper lid sliding pin 10d first comes into contact are aligned. Can be smoothly inserted into the upper lid cam groove 13.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a side view showing the upper cassette half 45 of the magnetic tape cassette 40 according to the second embodiment of the present invention.

As shown in FIG. 3, the magnetic tape cassette 4
The upper cassette half 45 has upper lid cam grooves 46 formed on both side surfaces thereof. The upper lid cam groove 46 is provided with an opening 48 that opens toward the front of the upper cassette half 45. As a characteristic configuration of the present embodiment, the cam groove ceiling portion 48a and the cam groove bottom portion 48b of the opening portion 48 are set at the same position in the vertical direction, as shown by a dashed line. That is, the entrance of the upper cover cam groove 46 is aligned with the insertion direction of the upper cover sliding pin 10d shown in FIG. 2 by extending the cam groove bottom 48b as compared with the conventional upper cover cam groove 46. The extended portion is thicker than the extended portion described in JP-A-10-334637 shown in the conventional example, and has sufficient strength. The distance X between the cam groove ceiling 48a and the cam groove bottom 48b of the opening 48 is set to be equal to or larger than the diameter D of the upper lid sliding pin 10d. Therefore, the same operation and effect as those of the first embodiment can be obtained.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a side view showing the upper cassette half 55 of the magnetic tape cassette 50 according to the third embodiment of the present invention.

As shown in FIG. 4, the magnetic tape cassette 5
0, upper cover cam grooves 56 are formed on both side surfaces of the upper cassette half 55. The upper cover cam groove 56 is provided with an open portion 58 that opens toward the front of the upper cassette half 55. As a characteristic configuration of the present embodiment, the cam groove ceiling portion 58a and the cam groove bottom portion 58b of the opening portion 58 are set at the same position in the vertical direction, as shown by a dashed line. That is, the entrance of the upper lid cam groove 56 is aligned with the insertion direction of the upper lid sliding pin 10d shown in FIG. 2 by extending the cam groove bottom 58b as compared with the conventional upper lid cam groove 56. This extended portion is thicker than in the second embodiment, and can be made sufficiently strong. Also, as in the first and second embodiments, the cam groove ceiling 48a and the cam groove bottom 48
b is set to be equal to or greater than the diameter D of the upper lid sliding pin 10d. Therefore, the same operation and effect as those of the above-described first and second embodiments can be obtained.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 5 is a side view showing the upper cassette half 65 of the magnetic tape cassette 60 according to the fourth embodiment of the present invention.

As shown in FIG. 5, the magnetic tape cassette 6
The upper cassette half 65 has upper lid cam grooves 66 formed on both side surfaces thereof. The upper lid cam groove 66 is provided with an opening 68 that opens toward the front of the upper cassette half 65. As a characteristic configuration of the present embodiment, an end 68c of the cam groove ceiling 68a of the opening 68 is a curved surface. That is, the portion that first comes into contact when the inner lid sliding pin 10d is inserted has a curved surface. Also, the first
As in the third embodiment, the distance X between the cam groove ceiling 68a and the cam groove bottom 68b of the opening 68 is equal to or greater than the diameter of the upper lid sliding pin 10d. The moving pin 10d is smoothly inserted into the upper lid cam groove 68 while being guided by the curved surface.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 6 is a side view showing the upper cassette half 75 of the magnetic tape cassette 70 according to the fifth embodiment of the present invention.

As shown in FIG. 6, the magnetic tape cassette 7
0, upper cover cam grooves 76 are formed on both side surfaces of the upper cassette half 75. The upper lid cam groove 76 is provided with an opening 78 that is open toward the front of the upper cassette half 75. As a characteristic configuration of the present embodiment, a horizontal portion 78d extending in the horizontal direction from the cam groove ceiling portion 78a of the opening portion 78 is provided, and an end portion 78c of the horizontal portion 78d is a curved surface. That is, the horizontal direction in which the inner lid slide pin 10d is inserted is parallel to the horizontal portion 78d, and the portion that first comes into contact when the inner lid slide pin 10d is inserted has a curved surface. Further, similarly to the first to fourth embodiments, the distance X between the cam groove ceiling portion 78a of the open portion 78 and the cam groove bottom portion 78b is equal to the upper lid sliding pin 10.
Since the diameter is equal to or larger than the diameter d, the upper-lid sliding pin 10d is smoothly inserted into the upper-lid cam groove 78 by the horizontal movement.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 7 is an enlarged side view showing the upper cassette half 85 of the magnetic tape cassette 80 according to the sixth embodiment of the present invention.

As shown in FIG. 7, the magnetic tape cassette 8
The upper cassette half 85 has upper cam grooves 86 formed on both side surfaces thereof. The upper cover cam groove 86 is provided with an opening 88 that is open toward the front of the upper cassette half 85. As a characteristic configuration of the present embodiment, a horizontal portion 88d extending horizontally from the cam groove ceiling portion 88a of the opening portion 88 is provided, and an end portion 88c of the horizontal portion 88d is a curved surface, Further, an inclined surface 88e is formed from the curved end portion 88c toward the front of the cassette. That is, the horizontal direction in which the inner lid sliding pin 10d is inserted and the horizontal portion 88d are parallel to each other, and the first contact portion when the inner lid sliding pin 10d is inserted is the inclined surface 88d.
c and a curved surface 88c. Also, as in the first to fifth embodiments, the cam groove ceiling portion 88a of the open portion 88 is provided.
The distance X between the upper cover sliding pin 10d and the upper cover sliding pin 10d is greater than or equal to the diameter of the upper cover sliding pin 10d, so that the upper cover sliding pin 10d is smoothly inserted into the upper cover cam groove 88 by the horizontal movement.

Although the first to sixth embodiments of the present invention have been described above, the shape of the upper cassette half may be applied even if it is as follows. FIG. 8 is a side view of the upper cassette half 95. As shown in FIG. 8, the upper cassette half 95 differs from the above-described embodiment in that a pin support hole 97 into which the support pin 9c of the outer lid 9 is fitted is open toward the lower surface of the cassette. The entrance is narrow and inwardly widened so as not to escape. In order to insert the pivot pin 9c into such a pin support hole 97, both the horizontal movement and the vertical movement must be performed, so that the top lid 10 and the outer lid 9 are rotated by a predetermined amount with respect to each other. Although it is necessary to be in the state, even with such a shape of the upper cassette half 95, the insertion can be performed smoothly by satisfying the conditions of the above-described first to sixth embodiments. It is preferable that the support pin 9c has an inclined surface 95h at the tip of the upper half 95. With such a shape, even if it is not the shape as in the above-described embodiment, the inclined surface 95
h guides the support pin 9c, so that the support pin 9c
This is because the fitting of c can be easily performed, and as a result, the upper lid sliding pin 10d can be easily inserted.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that modifications and improvements can be made as appropriate.

[0039]

As described above, according to the first aspect of the present invention, the cam groove ceiling portion and the cam groove bottom portion of the open portion are at the same position in the vertical direction, and the cam groove ceiling portion of the open portion and the cam Since the distance from the groove bottom is equal to or larger than the diameter of the upper lid sliding pin, the upper lid sliding pin is smoothly inserted into the upper lid cam groove by the horizontal movement. Therefore, the operation of inserting the upper lid sliding pin can be performed smoothly, and the cassette can be easily assembled.

According to the magnetic tape cassette of the present invention, the end of the portion extending from the cam groove ceiling of the open portion is curved, and the cam groove ceiling of the open portion and the cam are closed. Since the distance from the groove bottom is equal to or greater than the diameter of the upper lid sliding pin, the upper lid sliding pin is smoothly inserted into the cam groove while being guided by the curved surface by the horizontal movement.
Therefore, the operation of inserting the upper lid sliding pin can be performed smoothly, and the cassette can be easily assembled.

According to the magnetic tape cassette of the third aspect, a portion extending in the horizontal direction from the cam groove ceiling portion of the open portion is provided, and the cam groove ceiling portion and the cam groove bottom portion of the open portion are provided. Is larger than the diameter of the upper lid sliding pin, the upper lid sliding pin is smoothly inserted into the cam groove by the horizontal movement. Therefore, the operation of inserting the upper lid sliding pin can be performed smoothly, and the cassette can be easily assembled.

[Brief description of the drawings]

FIG. 1 is a side view showing an upper cassette half 35 of a magnetic tape cassette 30 according to a first embodiment of the present invention.

FIG. 2 is a view showing one process of an assembling method of the magnetic tape cassette 30 having the three-sheet type opening / closing lid of the first embodiment.

FIG. 3 is a side view showing an upper cassette half 45 of a magnetic tape cassette 40 according to a second embodiment of the present invention.

FIG. 4 is a side view showing an upper cassette half 55 of a magnetic tape cassette 50 according to a third embodiment of the present invention.

FIG. 5 is a side view showing an upper cassette half 65 of a magnetic tape cassette 60 according to a fourth embodiment of the present invention.

FIG. 6 is a side view showing an upper cassette half 75 of a magnetic tape cassette 70 according to a fifth embodiment of the present invention.

FIG. 7 is a side view showing an upper cassette half 85 of a magnetic tape cassette 80 according to a sixth embodiment of the present invention.

FIG. 8 is a diagram showing a method of assembling an opening / closing lid on an upper cassette half 95 having a shape different from that of the first to sixth embodiments.

FIG. 9 is a perspective view of a conventional magnetic tape cassette.

FIG. 10 is a longitudinal sectional view of a conventional magnetic tape cassette.

11 is a view showing a state in which the open / close lid of FIG. 10 is opened.

FIG. 12 is a view showing one step of a conventional magnetic tape cassette assembling method.

[Explanation of symbols]

9 Outer lid 10 Top lid 11 Inner lid 30, 40, 50, 60, 70, 80 Magnetic tape cassette 35, 45, 55, 65, 75, 85 Upper cassette half 36, 46, 56, 66, 76, 86 Upper lid cam Grooves 38, 48, 58, 68, 78, 88 Open portions 38a, 48a, 58a, 68a, 78a, 88a Cam groove ceiling portions 38b, 48b, 58b, 68b, 78b, 88b Cam groove bottom portions 68c, 78c, 88c End portions 78d, 88d Horizontal section 88e Inclined section

Claims (3)

[Claims] An opening / closing lid having an outer lid, a top lid, and an inner lid; and an upper lid sliding pin projecting from a side plate of the top lid. An upper lid cam groove provided on both side surfaces of the cassette half, wherein the upper lid cam groove is a magnetic tape cassette having an open part opened forward of the upper cassette half; A magnetic tape, wherein a bottom portion is set at the same position in the vertical direction, and a distance between the cam groove ceiling portion of the open portion and the cam groove bottom portion is equal to or larger than a diameter of the upper lid sliding pin. cassette. 2. A cassette body comprising upper and lower cassette halves, an opening / closing lid having an outer lid, a top lid, and an inner lid; and an upper lid sliding pin projecting from an inner side plate of the top lid. An upper lid cam groove provided on both side surfaces of the cassette half, wherein the upper lid cam groove extends from a cam groove ceiling of the open part in a magnetic tape cassette having an open part opened forward of the upper cassette half. A magnetic tape cassette, wherein an end of a portion to be formed has a curved surface, and a distance between the cam groove ceiling portion and the cam groove bottom portion of the open portion is equal to or larger than a diameter of the upper lid sliding pin. . 3. A cassette body comprising upper and lower cassette halves, an opening / closing lid having an outer lid, a top lid, and an inner lid; and an upper lid sliding pin projecting from a side plate inside the top lid. An upper lid cam groove provided on both side surfaces of the cassette half, wherein the upper lid cam groove is a horizontal direction from a cam groove ceiling of the open part in the magnetic tape cassette having an open part opened forward of the upper cassette half. A magnetic tape cassette, wherein a distance between the cam groove ceiling portion and the cam groove bottom portion of the open portion is equal to or greater than the diameter of the upper lid sliding pin. .