GB2069742A

GB2069742A - Tape reel discrimination system

Info

Publication number: GB2069742A
Application number: GB8041368A
Authority: GB
Original assignee: Victor Company of Japan Ltd; Nippon Victor KK
Current assignee: Victor Company of Japan Ltd; Nippon Victor KK
Priority date: 1979-12-28
Filing date: 1980-12-29
Publication date: 1981-08-26
Also published as: DE3049296C2; GB2069742B; MY8700573A; FR2472813A1; FR2472813B1; DE3049296A1

Abstract

A system is provided for indicating the type of tape reels, such as the diameter of hubs in a video tape cassette, being used. The system comprises detecting means 13, 14, 15, 16, 17 which provide signals corresponding to the rotational periods or number of rotations of the tape supply and take-up reels 11, 12. These signals are added in an adder 21 and the resulting signal is supplied to a comparator 22 whose output is supplied to an indicator 23. From the indicated hub size, it is possible to determine the type of cassette while it is being recorded or played so as to have some indication of its time capacity. <IMAGE>

Description

SPECIFICATION Tape reel discrimination system The present invention generally relates to tape reel type discriminating systems, and more particularly to a tape reel tape discriminating system which discriminates the type of diameter of a tape reel contained within a tape cassette and further discriminates the remaining tape quantity on a supply reel by use of the result obtained from the discrimination upon necessity.

Generally, a tape cassette used in a cassette type magnetic recording and/or reproducing apparatus (hereinafter referred to as VTR) which records and/or reproduces a video signal on and/or from a cassette tape, comprises various types according to the recording and/or reproducing time capacity of the tape cassette. That is, the outer size of the cassette case is the same regardless of the recording and/or reproducing time capacity of the tape cassette, however, the quantity of the magnetic tape and the diameter of the reel hub contained within the cassette case differ according to the above recording and/or reproducing time capacity of the tape cassette.

As a tape cassette used in recording and reproducing a television signal of the NTSC system, for example, there are such types in which the recording and/or reproducing time capacity is 120 minutes (T-120),90 (T-90), 60 minutes (T-60), 30 minutes (T-30), and 20 minutes (T-20) according to the differing quantity of magnetic tape contained within the cassette case. Similarly, as a tape cassette used in recording and/or reproducing a television signal of the PAL system, there are such types in which the recording and/or reproducing time capacity is 240 minutes (E-240), 180 minutes (E-180), 120 minutes (E-120), 60 minutes (E-60), 30 minutes (E-30), and 20 (E-20).Furthermore, two types of reel hub diameters are used, mainly, a reel hub having a diameter of 26 mili-meters and a reel hub having a diameter of 62 mili-meters. These different types of reel hub diameters are shown in the following table.

TABLE Reel hub diameter 26 mili-meters 62 mili-meters Type of system T-60 NTSC system T-120 T-30 T-90 T-20 E-240 E-60 PAL system E-180 E-30 E-120 E-20 Hence, the user of the VTR often uses the tape cassette without confirming or recognizing the type of the tape cassette. Accordingly, it will be very useful, if the type of reel hub diameter is automatically displayed.

Moreover, it will be even more useful, if the remaining quantity of the magnetic tape on the supply reel is displayed.

Accordingly, a general object of the present invention is to provide a novel and useful tape reel type discriminating system which has satisfied the above described demands.

The present invention provides a tape reel types discriminating system comprising a detecting step for respectively detecting rotation periods or numbers of rotations according to the respective rotation of a tape supply reel and a tape take-up reel, an adding step for adding the rotation periods or the numbers of rotations respective of the two reels obtained from said detecting step, and a comparing and discriminating step for comparing the added value obtained by said adding step and discriminating the hub diameter of the reel.

Another and more specific object of the present invention is to provide a tape reel type discriminating system for discriminating the type of hub diameter of the tape reel. The tape reel type cannot be discriminated by using only the rotation period of the supply reel or the take-up reel. Thus, according to the system of the present invention, the tape reel type is discriminated by using the rotation period (or the number of rotations) of the supply reel and the rotation period (or the number of rotations) of the take-up reel.

Still another object of the present invention is to provide a system for performing arithmetic operations and displaying the remaining tape quantity by use of the result obtained from the above tape reel type discrimination.

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

Figure 1 is a systematic block diagram showing an embodiment of a system according to the present invention; Figure2 is a graph for explaining the variation in the rotation period of a reel according to the tape reel type; Figures 3A and 3B are graphs respectively showing the sum of the rotation periods at the supply reel and the take-up reel according to the tape reel type; and Figure 4 is a flow-chart showing the remaining tape quantity displaying operation.

The period and the remaining tape quantity time of a reel disc will first be calculated by use of equations.

When the following quantities are designated by the symbols shown on their right hand side, overall length ofthetape ---LA tape length wound on the take-up reel after tseconds remaining tape quantity remaining on the supply reel aftertseconds ---0 tape travelling speed ---V thickness of tape ---h outermost tape radius of the tape in a state in which the tape is not drawn out wound tape radius on the supply reel after tseconds wound tape radius on the take-up reel after tseconds rotation period of the supply reel dise ---fs rotation period of the take-up reel disc ---fT reel hub radius the following equations are obtained at the supply reel.

Similarly, at the take-up reel, the following equation is obtained.

Hence, a sum Fof the rotation period fs of the supply reel and the rotation period fT of the take-up reel becomes as follows.

On the other hand, at the supply reel,

and the remaining quantity time Tq of the supply reel can be described by the following equation (2).

Accordingly, when the reel hub radius rand the rotation period fs of the supply reel disc are given, the remaining tape quantity time Tq can be obtained.

An embodiment of a tape reel type discriminating system according to the present invention, will now be described in conjunction with Figure 1. The present embodiment is capable of obtaining the type of the above reel hub radius rand the remaining tape quantity time Tq of the supply reel.

A magnetic tape 10 is drawn out from a supply reel 11 and wound up by a take-up reel 12. The radius of the respective reel hubs 11 a and 12a of the reels 11 and 12, differ according to the type of tape cassette which contains these reels, where the types of tape cassettes are as described above. The rotation of the reels 11 and 12, are detected by rotation detectors 13 and 14. These rotation detectors 13 and 14 can be of a known construction, for example, in which a light emitting diode and a phototransistor are provided opposing each other, and a rotary plate having tooth-shaped slots thereon and provided on the rotating axis of the reel, is inserted between the light emitting diode and the phototransistor.The rotation detectors 13 and 14 produce forty-eight pulses as output, every one rotation of the reels 11 and 12, that is, for every one rotation of the above rotary plate.

The output pulses of the rotation detectors 13 and 14 are supplied to counters 15 and 16. The counters 15 and 16 respectively count the clock pulses having constant frequency which are supplied from an oscillator r17, until the number of pulses supplied from the rotation detectors 13 and 14 reach a predetermined value, for example, forty eight pulses. When the clock pulses supplied from the oscillator 17 are counted until the number of pulses supplied from the rotation detectors 13 and 14 reach forty-eight pulses, for example, the counted value is a value which is proportional to the time required for the reels 11 and 12 to undergo one rotation. Accordingly, output signals respective of the rotation periods of the reels 11 and 12 are obtained from the counters 15 and 16.

The output signals of the counters 15 and 16 are supplied to multipliers 18 and 19, wherein the signals are multiplied by a constant respective of a normal mode tape travelling speed (for example,33.35 mili-meters per second in the case of the NTSC system, and 23.39 mili-meters per second in the case of the PAL system) which is supplied from a tape speed setting device 20. Therefore, when the tape 10 is travelling at two times the normal tape travelling speed, for example, conversions are performed in the multipliers 18 and 19 so that the above value becomes identical to when the tape is travelling at a normal tape travelling speed. Hence, signals respective of the rotation periods f5 and fT of the respective supply reel 11 and the take-up reel 12, can be obtained from the multipliers 18 and 19.

The output signals of the multipliers 18 and 19 are supplied to an adder 21 wherein the signals are added, and thus, a signal which can be described by the above equation (1) and respective of a rotation period (fs + fT) can be obtained. The output signals of the adder 21 is supplied to a comparator 22, wherein the signal thus supplied to the comparator 22 is compared with a threshold period which is predetermined according to the type of hub diameters of the tape reel. This threshold period is, for example, set at 12.1 seconds in the NTSC system, and 17.2 seconds in the PAL system.When the signal supplied to the comparator 22 is lower than the threshold period, discrimination is made that a tape cassette comprising tape reels having reel hubs which are 26 mili-meters in diameter is being used, that is, a tape cassette of the above T-120, T-90, E-240, E-180, or E-1 20 type is being used. On the other hand, when the signal supplied to the comparator 22 is higher than the threshold period, discrimination is made that a tape cassette comprising tape reels having reel hubs which are 62 mili-meters in diameter is being used, that is, a tape cassette of the above T-60, T-30, T-20, E-60, E-30, or E-20 type is being used.

The output of the comparator is supplied to a cassette indicator 23, wherein the above tape cassette type respective of the above hub diameter is displayed.

The above described principle will now be described in conjunction with Figure 2. When a T-30 type tape cassette is used, for example, the rotation periods of the tape supply reel and the tape take-up reel respectively vary with respect to time, as shown approximately by the solid lines land II. If these rotation periods shown by the solid lines land II are added, the resulting sum of the rotation periods becomes as shown by the solid line Ill. Hence, in accordance with the tape travel, the rotation period of the tape supply reel becomes short (small), and the rotation period of the tape take-up reel becomes long (large), however, the sum of the two rotation periods is always a substantially constant value.Similarly, when a T-60 type tape cassette is used, the rotation periods of the tape supply reel and the tape take-up reel respectively vary with respect to time, as shown approximately by the dotted lines IV and V. If these rotation periods shown by the dotted lines IV and Vare added, the resulting sum of the rotation period becomes as shown by the dotted lines VI. Therefore, in accordance with the tape travel, the rotation period of the tape supply reel becomes short (small), and the rotation period of the tape take-up reel becomes long (large), however, the sum of the two rotation periods is always a substantially constant value.The value shown by the above dotted lines VI is larger than the value shown by the solid line III. These values shown by the solid line Ill and the dotted lines VI, are respectively compared with the threshold period and discriminated at the comparator 22.

By focusing on either the tape supply reel or the tape take-up reel, since the rotation period varies in accordance with the tape travel, the type of reel being used cannot be discriminated. However, by adding the rotation periods of the two reels as in the system of the present invention, the added value shows a substantially constant yet different value according to the type of reel being used, enabling the discrimination to be performed.

Furthermore, upon performing of the above discrimination, an average value between the two rotation periods respective of the reels can be used, without adding the rotation periods of the two reels. In this case, the above average value for the T-30 type tape cassette becomes as shown by the one-dot chain line VII of Figure 2. The above average value for the T-60 type tape cassette becomes as shown by the two-dot chain line VIII, and thus, discrimination of the above two average values VII and VIII is possible. Moreover, the number of rotations which is in a reciprocal relationship with the rotation period, can be used without the use of the rotation period.

In the graph of Figure 2, the variation of the rotation period is shown linearly in order to simplify the description of the operating principle, however, in reality, the rotation period of the reel vary non-linearly in response to the variance in the diameter of the wound tape on the reel. Accordingly, the sum of the rotation periods between the tape supply reel and the tape take-up reel, actually vary non-linearly as shown in Figures 3A and 3B. Figure 3A shows the variation in the sum of the rotation periods of the reels, for the tape cassette types T-20, T-30, T-60, T-90, and T-120. On the other hand, Figure 3B shows the variation in the sum of the rotation periods of the reels, for the tape cassette types E-20, E-30, E-60, E-120, and E-240.As clearly seen from Figures 3A and 3B, although the sums of the rotation periods of the reels are actually non-linear, the respective sums of the different types of tape cassettes show completely different values, and the comparison between the threshold period and the discrimination at the comparator 22, can accordingly be performed with ease and certainty.

Referring back to Figure 1, the output signals of the multiplier 18 and the comparator 22 are respectively supplied to an arithmetic operator 24. The arithmetic operator 24 performs an arithmetic operation described by the above equation (2). Therefore, the arithmetic operator 24 performs the arithmetic operation by assuming the terms V/4hz and zr2/hV as constants, and f52 as a variable in equation (2), and produces an output signal which indicates the remaining tape quantity on the supply reel 11 in terms of time (that is, a time indicating the remaining minutes wherein recording and/or reproducing can be performed).

The output signal of the arithmetic operator 24 is supplied to an indicator 26 through an indicator driving circuit 25, and the indicator 26 displays the remaining tape quantity in terms of time, obtained as a result of the above arithmetic operation. Accordingly, the user of the VTR can easily see the type of tape cassette being used from the indicator 23, and furthermore see the remaining tape quantity from the indicator 26 with ease.

Moreover, the displaying function of the tape cassette type by the indicator 23, which uses the compared result obtained from the comparator 22 to perform the arithmetic operation concerning the remaining tape quantity, can be omitted.

An embodiment capable of performing the operations of the system according to the present invention was shown by the systematic block diagram of Figure 1, however, in realizing the above system, a part of the block system enclosed by dotted lines of Figure 1 is realized by using the functions of a micro-computer. The above tape cassette type discrimination, remaining tape quantity computation or operation, and the display operation in the above case, will be described in conjunction with the flow-chart of Figure 4. The operation starts at a step 30, and a clear operation is performed at a step 31 in which such operation as clearing the display in the indicator, is performed. At a following step 32, the state of insertion of the tape cassette is judged, and judgement of whether the system is in a play mode is performed by a step 33.Judgement is made on whether the reproduction mode is in a normal reproduction mode or a two times normal speed reproduction mode, at a following step 34.

When the judgement result at the step 34 is NO, that is, when the reproduction mode is in a normal reproduction mode, forty-eight pulses are counted for every one rotation of the take-up reel 12 at a step 35, and forty-eight pulses are counted for every one rotation of the supply reel 11 at a step 36. The rotation periods of the two reels obtained according to the above counted value, are added at a following step 37. On the other hand, when the judgement result at the step 34 is YES, that is, when the reproduction mode is in a two times normal speed reproduction mode, forty-eight pulses are counted every two rotations of the take-up reel 12 at a step 38, and forty-eight pulses are counted every two rotations of the supply reel 11 at a step 39.Accordingly, a rotation period which has been converted into that corresponding to the normal speed, can be obtained even through the production mode is in a two times normal speed reproduction mode. As a result, the above described functions performed, are equal to those performed by the counters 15 and 16, and the multipliers 18 and 19. The rotation periods of the reels obtained at the steps 38 and 39, are added at the step 37.

After the addition of the rotation periods of the two reels at the step 37, judgement is performed at a step 40 to judge whether the added value of the rotation period obtained from the step 37 is larger than 16.5 seconds. This step 40 corresponds to the comparator 22 which performs the comparing operation.

When the judgement result at the step 40 is NO, that is, when the sum of the rotation periods of the two reels is smaller than 16.5 seconds, indicates that the diameters of the reel hubs were judged as being small.

This means that discrimination was made that the tape cassette being used is of the E-1 20 or E-180 type, for example. In this case, steps 41 j, 41 i, 41 h,---, 41 b and 41 a are successively performed, and the sum of the rotation periods are compared with each of the predetermined rotation period values respective of the times 100 minutes, 90 minutes, 80 minutes, ---,20 minutes, and 10 minutes corresponding to the remaining tape quantities, at each of the above steps.In a case where the judgement result obtained by the above comparison is YES, the corresponding light emitting element (LED) is turned ON at the corresponding steps 42j, 42i, 42h,---, 42b, and 42a, and the remaining tape quantity in terms of time is displayed showing the remaining time, mainly, 100 minutes, 90 minutes, 80 minutes, ---,20 minutes or 10 minutes. When the remaining tape quantity in terms of time becomes less than 10 minutes long, an indicator light flashes at a step 43, to indicate the small remaining tape quantity. Furthermore, when the remaining tape quantity in terms of time is more than 100 minutes long, it is unnecessary to know the accurate remaining quantity, and a display indicating the remaining quantity of 100 minutes, is displayed in this case.

On the other hand, when the judgement result at the step 40 is YES, that is, when the sum of the rotation periods of the two reels is larger than 16.5 seconds, indicates that the diameters of the reel hubs were judged as being large. This means that discrimination was made that the tape cassette being used is of the E-30, E-60, or E-90 type, for example. In this case, steps 44i, 44h, 44g,---, 44b, and 44a are successively performed, and the sum of the rotation periods are compared with each of the predetermined rotation period values respective of the times 90 minutes, 80 minutes, 70 minutes, ---,20 minutes, and 10 minutes corresponding to the remaining tape quantities, at each of the above steps. In a case where the judgement result obtained by the above comparison is YES, the corresponding light emitting element, LED, is turned ON at the corresponding steps 45i, 45h, 45g---, 45b, and 45a, and the time corresponding to the remaining tape quantity is displayed showing the remaining time, mainly, 90 minutes, 80 minutes, 70 minutes,---, 20 minutes, or 10 minutes. When the remaining tape quantity in terms of time becomes less than 10 minutes long, an indicator light flashes at a step 43, to indicate the small remaining tape quantity.

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

Claims

1. Atape reel types discriminating system comprising: a detecting step for respectively detecting rotation periods or numbers of rotations according to the respective rotation of a tape supply reel and a tape take-up reel; an adding step for adding the rotation periods or the numbers of rotations respective of the two reels obtained from said detecting step; and a comparing and discriminating step for comparing the added value obtained by said adding step and discriminating the hub diameter of the reel.

2. A system as claimed in claim 1 which further comprises indicating step for displaying the tape reel type according to the discrimination result obtained by said comparing and discriminating step.

3. A system as claimed in claim 1 which further comprises indicating step for displaying the remaining tape quantity on said tape supply reel by converting the remaining tape quantity into time, according to the discrimination result obtained from said comparing and discriminating step.

4. A system as claimed in claim 1 which further comprises indicating step for displaying the tape reel type according to the discrimination result obtained by said comparing and discriminating step, and indicating step for displaying the remaining tape quantity on said tape supply reel by converting the remaining tape quantity into time, according to the discrimination result obtained from said comparing and discriminating step.

5. A system as claimed in claim 1 which further comprises step for obtaining the rotation period or the number of rotations respective of the two reels detected by said detecting step so that the above value obtained is the same regardless of the tape travelling speed, and supplying the result thus obtained to said adding step.

6. Atape reel type discriminating system comprising: rotation detecting means for respectively generating pulses according to rotations of a tape supply reel and a tape take-up reel; counting means for producing an output rotation period signal according to the time required to count a predetermined number of pulses supplied from said rotation detection means; adding means for adding the respective rotation period signals respective of the rotations of the above two reels; and comparing means for comparing the output added value of said adding means with a predetermined threshold, and producing an output discrimination signal according to the result of the comparison, said discrimination signal being respective of the hub diameter type of the reel.

7. A system as claimed in claim 6 which further comprises indicating means for displaying the tape reel type according to the output supplied from said comparing means.

8. A system as claimed in claim 6 which further comprises arithmetic operation means for producing an output signal which indicates the remaining tape quantity on the tape supply reel obtained from the output of said comparing means in terms of time, and indicating means for displaying the remaining tape quantity in terms of time according to the output signal supplied from said arithmetic operation means.

9. A system as claimed in claim 6 which further comprises indicating means for displaying the tape reel type according to the output supplied from said comparing means, arithmetic operation means for producing an output signal which indicates the remaining tape quantity on the tape supply reel obtained from the output of said comparing means in terms of time, and indicating means for displaying the remaining tape quantity in terms of time according to the output signal supplied from said arithmetic operation means.

10. A system as claimed in claim 6 which further comprises multiplying means for multiplying a coefficient respective of the tape speed to the output of said counting means, to supply the resulting output to said adding means.

11. A tape reel types discriminating system substantially as described with reference to the accompanying drawings.