GB2119751A

GB2119751A - Video tape cassette cooperating with tape end detecting device

Info

Publication number: GB2119751A
Application number: GB08310949A
Authority: GB
Inventors: Yoshiaki Wakui
Original assignee: Victor Company of Japan Ltd; Nippon Victor KK
Current assignee: Victor Company of Japan Ltd; Nippon Victor KK
Priority date: 1982-04-28
Filing date: 1983-04-22
Publication date: 1983-11-23
Also published as: GB8310949D0; DE3315167A1; GB2119751B; DE3315167C2; KR840006388U; JPS58165795U; JPS6325595Y2; KR860001812Y1; FR2526208A1; BR8302101A; FR2526208B1

Abstract

A video tape cassette 10 is designed to cooperate with a tape end detecting device which comprises a light-emitting element 38 which relatively enters within the video tape cassette loaded into a predetermined position of a recording and/or reproducing apparatus, and first and second light-receiving elements 39, 40 positioned on both sides of the loaded video tape cassette for receiving light from the light-emitting element which has passed through transparent tape ends and windows 36, 37 in the casing, the remainder of the tape being opaque. The cassette case itself is molded from a synthetic resin having a colour other than black, and predetermined parts, e.g. 44, 14b, 15b, 63-69, of the case's inside surface in the vicinity of the eight paths are made black, e.g. by spraying, painting or dual-colour moulding, so that external light entering through the casing wall or through a tape- observing window in the casing or light from element 38 is not reflected within the casing, so giving an erroneous reading, 63, 64, 65, 67, 68, 69 within the cassette case in the vicinity of light paths reaching the first and second light-receiving elements through the first and second windows are made black. <IMAGE>

Description

SPECIFICATION Video tape cassette cooperating with tape end detecting device The present invention generally relates to video tape cassettes designed to cooperate with tape end detecting devices, and more particularly to a video tape cassette designed to cooperate with a tape end detecting device of an optical type, and prevent erroneous detection of an end of a tape although the video tape cassette has a cassette case molded from a synthetic resin having a color such that light may be transmitted through and reflected within the cassette case.

A tape end detecting device for detecting an end of a tape within a video tape cassette, where a video signal is recorded onto and reproduced from the tape, has been proposed in a British Patent No. 1,561,443 and reduced to practice.

The tape cassette comprises a first reel having an opaque tape wound thereon, with one end of the tape connected to a transparent first leader which is fixed at its other end to a hub of the first reel. A second reel receives the tape as it is wound. This tape is connected to one end of a second transparent leader which is fixed at its other end to a second reel hub. A cassette case containing the reels has first and second windows in at least one side wall. The tape end detecting device comprises at least one light-emitting element and first and second light-receiving elements respectively disposed on opposite sides of the tape, relative to the first and second windows.

The light-receiving elements detect the tape ends in response to their reception on light passing through the first and second windows.

Conventionally, in the tape cassette which cooperates with such a tape end detecting device, the light reaching the light-receiving elements was limited to the light emitted from the lightemitting element and passed through the transparent leaders and the first and second windows provided in the side walls of the cassette case. Hence, in order to prevent unwanted incoming light from reaching the light receiving elements, the cassette case was molded entirely from a black synthetic resin.

However, if the tape cassette is black in its entirety, there is no sense of beauty and there is no decorative touch to the tape cassette.

Recently, a large variety of prerecorded video tape cassettes containing tapes which are pre recorded with certain video signal programs, are being marketed and used. In these prerecorded video tape cassettes, there is a demand to make the tape cassettes attractive in their design.

Moreover, it will be useful for the user if the color of the cassette cases are different according to the kind of prerecorded video signal program, that is, whether the prerecorded video signal program is an educational program, program for infants, entertainment program, and the like, for example.

By providing cassette cases with different colors according to their prerecorded contents, the user will be able to easily distinguish the kind of prerecorded video signal program of a particular tape cassette, by simply distinguishing the color of the cassette case.

Accordingly, from the point of view of making the tape cassettes attractive in their design and make full use of the tape cassettes, there is now a demand to make the color of the cassette case an arbitrary color other than black, that is, red, orange, yellow, green, blue, and the like.

However, when a cassette case molded from a resin having a color other than black is used, the probabilities of the light reflecting within the cassette case and the light transmitting through the walls of the cassette case increase. Hence, the light emitted from the light-emitting element may be reflected within the cassette case, and the reflected light may reach the light-receiving elements through the windows in the side walls of the cassette case although the light actually is not transmitted through the transparent leader.

Further, light may be transmitted directly through the side walls of the cassette case, to reach the light-receiving elements. In such cases where the light is reflected within the cassete case or transmitted directly through the cassette case, the tape end detecting device will erroneously detect a tape end because the light-receiving element detects light, even though the tape is not fed out in its entirety from one of the reels, that is, even though a tape end has not been reached.

In order to visually detect the amount of tape wound around the reels from outside the cassette case with ease, transparent windows are formed at an upper surface of the cassette case. For this reason, even when the tape cassette is in a state loaded within a recording and/or reproducing apparatus, external light will enter within the cassette case through these transparent windows formed at the upper surface of the cassette case.

Thus, if the light reflection factor within the cassette case and the light transmission factor of the cassette case are large, the tape end detecting device will erroneously detect a tape end due to this external light. Especially when a portable type recording and/or reproducing apparatus is used outdoors under intensive light of the sun, a large quantity of light will enter within the cassette case through such transparent windows formed at the upper surface of the cassette case, and the tape end detecting device will more likely to carry out erroneous detection of a tape end.

Accordingly, it is a general object of the present invention to provide a novel and useful video tape cassette designed to cooperate with a tape end detecting device, in which the above described deficiencies have been eliminated.

The present invention provides a video tape cassette designed to cooperate with a tape end detecting device, said tape end detecting device comprising a light-emitting element which relatively enters within the video tape cassette loaded into a predetermined position of a recording and/or reproducing apparatus, and first and second light-receiving elements for receiving light from said light-emitting element, said first and second light-receiving elements being positioned on both sides of the loaded video tape cassette, said video tape cassette comprising, a first reel having a first hub, a second reel having a second hub, an opaque tape having first and second transparent leaders integrally fixed to opposite ends thereof, said tape being connected at opposite ends of said first and second leaders to said first and second hubs, and a cassette case for accommodating said first and second reels therein, said cassette case comprising a first window for allowing light which is emitted from said light-emitting element and passed through said first leader to reach said first light-receiving element, and a second window for allowing light which is emitted from said light-emitting element and passed through said second leader to reach said second light-receiving element, said cassette case itself being molded from a synthetic resin having a color other than black, predetermined parts within the cassette case in the vicinity of light paths reaching said first and second lightreceiving elements through said first and second windows being made black.

Another and more specific object of the present invention is to provide a video tape cassette comprising a cassette case which is molded from a synthetic resin having an arbitrary color other than black, so that an optical tape end detecting device will not carry out erroneous detection of a tape end. The outer surface of the cassette case of the video tape cassette according to the present invention is of an arbitrary color other than black, and the color of a part of the inner surface of the cassette case is black.

Because a part of the inner surface of the cassette case is black, there is no unwanted reflection and transmission of light within the cassette case, and unwanted light is prevented from reaching lightreceiving elements of the tape end detecting device. According to the video tape cassette of the present invention, the cassette case of the tape cassette can assume an arbitrary color other than black, and still prevent the tape end detecting device from erroneously detecting a tape end.

Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.

Figs. 1A and 1 B are a bottom perspective view, and a top perspective view with a part cut away, respectively showing an embodiment of a video tape cassette according to the present invention; Fig. 2 is a plan view showing a video tape cassette in a state cooperating with a tape end detecting device of a recording and/or reproducing apparatus; Fig. 3 is a plan view showing a lower half of a cassette case, for explaining the black part of the cassette case in the video tape cassette according to the present invention; and Fig. 4 is a graph showing relationships between an output voltage of a light-receiving element of the tape end detecting device and the illumination at the upper surface of the recording and/or reproducing apparatus, when various embodiments of a video tape cassette according to the present invention are used.

A video tape cassette according to the present invention has an external shape identical to that of the conventional video tape cassette, as shown in Figs. 1 A and 1 B. A tape cassette 10 has an outer housing structure comprising a cassette case 11 and a lid 12. The cassette case 11 consists of an upper half 11 a and a lower half 11 b. These upper and lower halves 11 a and 11 b are respectively molded from a resin such as acrylonitrile butadiene styrene (ABS) resin and high impact styrol resin, and has a color other than black such as red, for example. The lid 12 may have the same color as the cassette case 11, or may have a different color. The cassettes case 11 accommodates therewithin, a freely rotatable tape supply reel 14 and a tape takeup reel 15 each for winding an opaque magnetic tape 13.

The bottom of the cassette case 11 has two shaft holes 17 and 18 for receiving reel drive spindles or shafts on a recording and/or reproducing apparatus 16. These shafts fit into hubs of the respective reels 14 and 15 when the tape cassette 10 is inserted into its loaded position in the recording and/or reproducing apparatus 16.

Transparent windows 60a and 60b are formed at the upper half 11 a of the cassette case 11, so that the amount of tape wound around the reels 14 and 15 can be visually detected from above the cassette case 11. Upper flanges 14a and 1 5a of the respective reels 14 and 15 are also molded from a transparent synthetic resin.

One end of the magnetic tape 13 is connected to an outer end of a first transparent leader which is fixed at its inner end to a hub 19 of the supply reel 14. The other end of the magnetic tape 13 is connected to an outer end of a second transparent leader which is fixed at its inner end to a hub 21 of the takeup reel 15. The magnetic tape 13 is guided by guide poles 23, 24, and 25 from the supply reel 14 to the take-up reel 15 during normal recording, reproducing, or fast forwarding mode operations, and from the takeup reel 15 to the supply reel 14 during rewinding.

Within the cassette case 11, a hole 26 receives a lamp and constitutes an opening at a position between the two reels 14 and 1 5 and near the front face side of the cassette case 11. This lamp fitting hole 26 is defined and bordered by a cylindrical wall 27, in which openings 27a and 27b are formed. Furthermore, at specific positions in ribs 28, 29, and 30 within the cassette case 11, cutouts or openings 31, 32, 33, 34, and 35 are formed. In addition, windows 36 and 37 are provided in the two side walls of the cassette case 11.

In the recording and/or reproducing apparatus 16, a light-emitting element such as a lamp 38, for example, fits into the hole 26 when the tape cassette 10 is inserted into its loading position. In the recording and/or reproducing apparatus 16, a light-receiving element such as a photocell 39, for example, is positioned to receive light emitted by the lamp 38 which passes through the openings 27a, 31, and 32 and the window 36. In addition, a photocell 40 receives the light emitted by the lamp 38 which passes through the openings 33 through 35 and the window 37.

The lid 12 is hinged by pivot pins 41 and 42 at the front face side of the cassette case 11 and is continually urged to swing toward a closed position by a torsion spring 43 around the pivot pin 42. When the tape cassette 10 is not loaded in the recording and/or reproducing apparatus 16, the lid 12 is closed, as indicated by broken lines in Fig. 1, to cover the magnetic tape 13 which is exposed at the front face of the cassette case 11.

When the lid 12 is closed, the windows 36 and 37 are covered by side parts 12a and 12b of the lid 12, to prevent infiltration of dust.

Within the cassette case 11, a lock plate 44 is rotatably supported by pivot pins 45a and 45b and urged by a torsion spring 46 to press against the inner surface of the case side wall. The lock plate 44 has an opening 47. Projections 48 and 49 on the side surface of the lock plate 44 project through openings in the side wall of the case. The projection 48 engages a recess 50 in the lid 12, when it is closed, thereby locking the lid 12 against opening. The projection 49 is disposed within a groove formed between the side wall of the lid 12 and the outermost surface of the cassette case 11 when the lid 12 is closed.

The tape cassette 10, with its lid 12 closed, is inserted horizontally onto and along a loading platform of the recording and/or reproducing apparatus 16. A leaf spring (not shown) has a projection at its free end and is fixed at its root end to the side of the loading platform. As the tape cassette 10 is inserted, the projection of the leaf spring presses the projection 49 toward the left, as viewed in Fig. 2. As a consequence, the lock plate 44 rotates, overcoming the force of the spring 46. The projection 48 is also displaced leftward and is disengaged from the recess 50 of the lid 12, thereby unlocking the lid 12.

Then, when the loading platform is thereafter lowered, the lower edge of the lid 12 presses against a lug 51 fixed to the recording and/or reproducing apparatus 16. Together with the downward movement of the tape cassette 10, the lid 12 engages the lug 51 and opens against the force of the spring 43, as indicated by full lines in Fig. 1. Consequently, the front of the magnetic tape 13 is revealed, and the window 37 opens.

On the downward movement of the tape cassette 10, the lamp 38 is fitted into the hole 26, and the reel drive shafts (not shown) are fitted into the shaft holes 17 and 18. At the same time, a capstan 59 and tape drawing out and loading members 52 and 53 fit into a recess on the front side of the cassette case 11.

When the recording and/or reproducing apparatus 16 is placed in the recording or reproducing mode of operation, an upper drum of a guide drum 54 having video heads begins to rotate. At the same time, the tape drawing out and loading members 52 and 53 move to the positions indicated by broken lines. The magnetic tape 13 wraps around a part of the guide drum 54. A pinch roller 55 presses the magnetic tape 13 against the capstan 59.

The magnetic tape 13 thus clamped by the capstan 59 and the pinch roller 55 is driven by the rotation thereof. The tape on the supply reel 14 is unwound and paid out to be wound up on the takeup reel 15. At the same time, video signals are recorded on or reproduced from the magnetic tape 13 by the video heads of the guide drum 54.

An audio signal is recorded or reproduced by an audio head 56.

During the recording or reproducing, the light from the lamp 38 should ideally be shut off by the magnetic tape 13 paid out or supplied from the supply reel 14 and wound or taken up by the takeup reel 15, so that the light does not reach the photocells 39 and 40. When the magnetic tape 1 3 has been completely paid out from the supply reel 14, and the recording or reproducing has been completed, the first transparent leader is paid out into the tape travel path between the reel hub 19 and the guide pole 24. Consequently, the light from the lamp 38, which until now has been shut off by the opaque magnetic tape 13, passes through the first leader and the window 36, reaching the photocell 39. This reception of the light by the photocell 39 means the detection of the end of tape. The resulting output detection signal of the photocell 39 stops the recording or reproducing operation.

The fast forwarding mode operation is carried out with the magnetic tape 13 accommodated within the cassette case 11. Upon completion of this fast forwarding mode operation, the light from the lamp 39 passes through the openings 31 and 32, the first leader, and the window 36, and is received by the photocell 39. The fast forwarding mode operation is thus stopped.

The rewinding of the magnetic tape 13 is also carried out with the magnetic tape 13 accommodated within the cassette case 11. Upon completion of the rewinding operation, the second transparent leader is paid out into the tape travel path between the reel hub 21 and the guide pole 25. As a consequence, the light from the lamp 38, which until now has been shut off by the opaque magnetic tape 13, passes through the second leader, the openings 33, 34, 35, and 47 and the window 37, and reaches the photocell 40. This reception of the light by the photocell 40 means the detection of the end of the tape which has completed its rewinding. The resulting output detection signal of the photocell 40 stops the rewinding operation.

As described before, the upper and lower halves 11 a and 11 b of the cassette case 11 are molded from a red synthetic resin, for example.

Hence, compared to the case where the upper and lower halves 11 a and 11 b are molded from a black synthetic resin, the light reflection factor within the cassette case 11 and the light transmission factor of the side walls of the cassette case 11 and the rib-shaped walls within the cassette case 11 respectively become large when the upper and lower halves 1 a and 1 b are molded from a red synthetic resin.

Accordingly, even when the magnetic tape 13 exists in the tape path so as to shut off the light path between the lamp 38 and the photocells 39 and 40, the light from the lamp 38 and the external light coming through the windows 60a and 60b reflect within the cassette 11, and the light may leak through the windows 36 and 37 to reach the photocells 39 and 40. Moreover, the light from the lamp 38 and the external light may be transmitted through the side walls and the ribshaped walls within the cassette case 11, to reach the photocells 39 and 40. Such undesirable phenomenons are especially notable when a portable type recording and/or reproducing apparatus, for example, is used outdoors under intensive light of the sun.In this case, even if the end of tape has not been reached, a light detection output is obtained from the photocell 39 or 40 to carry out erroneous detection of the end of tape.

Therefore, in the video tape cassette according to the present invention, the color at pre determined parts within the cassette case 11 is made black so that the above unwanted reflected light and transmitted light are not introduced. The present inventor has made six kinds of testing models in which parts within the cassette case 11 which are made black are different. The output voltage of the photocell 39 or 40 with respect to the illumination at the upper surface of the recording and/or reproducing apparatus was measured for the six testing models, and the results shown in Fig. 4 was obtained. In Fig. 4, the abscissa indicates the illumination and the ordinate indicates the output voltage of the photocell.

In Fig. 4, a line T, indicates the characteristic of a first video tape cassette tested in which only the lock plate 44 is molded from a black resin, and lower flanges 1 4b and 1 5b of the reels 14 and 15 are molded from a white resin while the whole cassette 11 is molded from a red resin. According to this first video tape cassette, even when the illumination at the upper surface of the recording and/or reproducing apparatus is low, the output voltage of the photocell 39 or 40 is high.Thus, if the tape end detecting device is designed so that the end of tape is detected when the output voltage of the photocell becomes equal to or greater than 3.16 volts, for example, that is, if a threshold value of the tape end detection is set to 3.1 6 volts, the end of tape is erroneously detected when the illumination at the upper surface of the recording and/or reproducing apparatus is equal to or greater than approximately 0.6x 104 Lx.

Hence, in this first video tape cassette, the above erroneous detection of the end of tape easily occurs, and is unfit for practical use.

In a second video tape cassette tested, only the lower flanges 1 4b and 1 5b of the reels 14 and 15 are molded from a black resin, and the whole cassette case 11 is molded from a red resin. The characteristic of this second video tape cassette is indicated by a line T2 in Fig. 4. In this case the light will not be reflected at the lower flanges 1 4b and 1 5b of the reels 14 and 1 5 because the lower flanges 1 4b and 1 5b are black. Hence, as clearly seen by comparing lines T1 and T2, a large output voltage will not be obtained from the photocell even when the illumination is relatively high. Therefore, the erroneous detection of the end of tape is less likely to occur in this second video tape cassette, compared to the first video tape cassette.However, in this second video tape cassette, the erroneous detection of the end of tape will occur when the illumination at the upper surface of the recording and/or reproducing apparatus is equal to or greater than 5x 104 Lx.

In a third video tape cassette tested, the lock plate 44, the lower flanges 1 4b and 1 5b of the reels 14 and 15, wall surfaces of chambers 61, 62 and 63 defined by the rib-shaped walls in the vicinity of the light path reaching the photocells 39 and 40, end surfaces of the openings 31 through 37 and 47, respectively are black, and the remaining parts of the cassette case 11 are red. This third video tape cassette was made by molding the whole cassette case 11 from a red resin, and spraying black paint on the above parts which are to be black. The characteristic of this third video tape cassette is indicated by a line Ts in Fig. 4. As clearly seen by comparing lines T2 and T3, the erroneous detection of the end of tape is less likely to occur in this third video tape cassette compared to the above second video tape cassette.According to the third video tape cassette, the erroneous detection of the end of tape will not occur unless the illumination at the upper surface of the recording and/or reproducing apparatus becomes considerably high, that is, equal to or greater than 7.5 x 104 Lx, for example.

In a fourth video tape cassette tested, the lock plate 44, the lower flanges 1 4b and 1 5b of the reels 14 and 1 5, wall surfaces of wall parts 63, 64, and 65 and parts 67 at the bottom surfaces of the upper and lower halves 1 a and 1 b respectively indicated by cross-hatchings in Fig.

3, are respectively black, and other parts of the cassette case 11 is red. Similarly as in the case of the third video tape cassette, the whole cassette case 11 was molded from a red resin, and the black paint was sprayed onto the parts which are to black. The characteristic of this fourth video tape cassette is indicated by a line T4 in Fig. 4. As clearly seen by comparing lines T3 and T4, the erroneous detection of the end of tape is less likely to occur in this fourth video tape cassette compared to the above third video tape cassette.

In a fifth video tape cassette tested, the parts which were made black in the fourth video tape cassette were also made black, and further, wall surfaces of side walls 68 and 69 of the cassette case 11 provided with the windows 36 and 37 and marked by dots in Fig. 3 were also made black. Other parts of the cassette case 1 1 were made red. The characteristic of this fifth video tape cassette is indicated by a line T5 in Fig. 4. As clearly seen by comparing lines T4 and T5, the erroneous detection of the end of tape is less likely to occur in this fifth video tape cassette compared to the above fourth video tape cassette.

According to the fourth and fifth video tape cassettes, the output voltage of the photocell does not become greater than the threshold value of 3.1 6 volts within the illumination range shown in Fig. 4, and the erroneous detection of the end of tape will not occur within this illumination range.

A sixth video tape cassette tested has the same construction as the above fifth video tape cassette, except in that the lower flanges 14b and 1 5b of the reels 14 and 15 are white in this sixth video tape cassette. The characteristic of this sixth video tape cassette is indicated by a line T5 in Fig. 4. By making the lower flanges 14b and 1 5b of the reels 14 and 15 white, it is seen that the sixth video tape cassette is inferior compared to the fourth and fifth video tape cassettes, however, the erroneous detection of the end of tape is less likely to occur in this sixth video tape when compared to the third video tape cassette.

In the above embodiments of the testing models the cassette case is first molded from the red resin and the black paint is sprayed or painted onto predetermined parts thereafter. However, the molding method of the cassette case is not limited to the above, and the cassette case may be molded by a molding device employing a dual color molding method which is widely used recently. According to this dual-color molding method, the whole cassette case is molded from a synthetic resin of an arbitrary color other than black, and the predetermined parts within the cassette case are molded from a black synthetic resin.

Further, the present invention is not limited to these embodiments, but various variations and modifications may be made without departing from the scope of the present invention.

Claims

1. A video tape cassette designed to cooperate with a tape end detecting device, said tape end detecting device comprising a light-emitting element which relatively enters within the video tape cassette loaded into a predetermined position of a recording and/or reproducing apparatus, and first and second light-receiving elements for receiving light from said light emitting element, said first and second light receiving elements being positioned on both sides of the loaded video tape cassette, said video tape cassette comprising: a first reel having a first hub; a second reel having a second hub; an opaque tape having first and second transparent leaders integrally fixed to opposite ends thereof, said tape being connected at opposite ends of said first and second leaders to said first and second hubs; and a cassette case for accommodating said first and second reels therein, said cassette case comprising a first window for allowing light which is emitted from said lightemitting element and passed through said first leader to reach said first light-receiving element, and a second window for allowing light which is emitted from said light-emitting element and passed through said second leader to reach said second light-receiving element, said cassette case itself being molded from a synthetic resin having a color other than black, predetermined parts within said cassette case in the vicinity of light paths reaching said first and second light-receiving elements through said first and second windows being made black.

2. A video tape cassette as claimed in claim 1 in which said predetermined parts within said cassette case are painted or sprayed with a black paint.

3. A video tape cassette as claimed in claim 1 in which said predetermined parts within said cassette case are molded according to a dualcolor molding method.

4. A video tape cassette as claimed in claim 1 in which said cassette case is provided with transparent windows for enabling visual detection of amount of tape wound around said first and second reels, and said predetermined parts within said cassette case correspond to parts where external light coming through said transparent windows in said cassette case become reflected and transmitted so as to reach said first and second light-receiving elements.

5. A video tape cassette as claimed in claim 1 in which said predetermined parts within said cassette case are wall surfaces of rib-shaped walls provided within said cassette case, in the vicinity of said light paths and said first and second windows.

6. A video tape cassette as claimed in claim 1 in which said predetermined parts within said cassette case are inner wall surfaces of side walls of said cassette case in the vicinity of said first and second windows.

7. A video tape cassette as claimed in claim 1 in which said predetermined parts within said cassette case are bottom surfaces within said cassette case in the vicinity of the window.