FR2472813A1 - DEVICE FOR DISCRIMINATION OR DETECTION OF THE TYPES OF COILS WITH A BAND OF VIDEO CASSETTES AND THE LIKE - Google Patents

Abstract

DEVICE FOR DISCRIMINATING THE TYPES OF CASSETTE TAPE COILS FOR VIDEO RECORDER PLAYERS COMPRISING SENSORS 13, 14 OF THE ROTATION 11, 12 ROTATION AND RECEIVING PERIODS, A MEMBER 21 PERFORMING A ROTATION BOB ADDING MEANS OF COMPARISON AND DISCRIMINATION 22 TO COMPARE THE VALUE DERIVED FROM THE ADDING MEMBER 21 TO A REFERENCE TO DETECT THE DIAMETER OF THE COIL HUB BY DEFINING ITS TYPE FOR EXAMPLE 60, 90, OR 120 MINUTES.

Description

The present invention relates generally to devices for

  discrimination of the type of tape reels, and more particularly a device for discriminating a tape from a reel discriminating or detecting the diameter of a reel contained inside a tape cassette and also the quantity of tape remaining on a supply reel using the result of discrimination when required

makes you feel.

  Generally, a tape cassette used in a cassette type magnetic recording and / or reproducing apparatus (to be referred to below by the abbreviation of CTR) which records and / or reproduces a video signal on and / or from the tape of a cassette,

  includes various types according to the capacity of the recording time

  recording and / or reproduction of the tape cassette. The outer diameter of the cassette box can actually

  be the same regardless of the length of the recording time

  recording and / or reproduction of the tape cassette, but the quantity of magnetic tape and the diameter of the reel hub which is contained inside the cassette may be different depending on the capacity of the recording time and / or reproduction mentioned above

of the tape cassette.

  With regard to tape cassettes used for recording and reproducing a television signal of the NTSC system, there may be mentioned types in which the capacity of the recording time and / or of

  reproduction is 120 minutes (T-120), 90 minutes (T-

  90), 60 minutes (T-60), 30 minutes (T-30) and 20 minutes (T-20) depending on the amount of magnetic tape inside the cassette. Likewise, when it comes to

  cassettes used for recording and / or reproduction

  tion of a PAL system television signal, there are types in which the capacity for recording and / or playing time is 240 minutes (E-240), 180 minutes (E-180), 120 minutes (E-120), 60 minutes

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  (E-60), 30 minutes (E-30) and 20 minutes (E-20). In addition, there are essentially two types of diameters for the coil hub, namely a hub whose diameter is 26 millimeters and a hub whose diameter is 62 millimeters. These different types of coil hub diameter are shown in the following table:

BOARD

  Hub diameter 26 millimeters 62 millimeters from coil Type of system T-60 System NTSC T-120 T-30

T-90 T-20

E-240 E-60

PAL system E-180 E-30

E-120 E-20

  As a result, the CTR user often uses the tape cassette without bothering to verify or recognize the type of cassette. As a result, it would be very useful to automatically display the type of diameter of the coil hub. In addition, it would be even more useful to display the remaining amount of magnetic tape contained

in the supply coil.

  Consequently, an object of the present invention is to create a new and useful discrimination device of the type of the tape reel satisfying the requirements described above. Another more specific object of the present invention is to create a device for discriminating the type of the tape reel making it possible to discriminate the type of diameter of the hub of the reel. The type of tape reel cannot be discriminated against if only the duration of rotation of the supply or take-up reel is used. Also, according to the device of the present invention, the type of the tape reel is discriminated using the period of rotation (or the number of rotations) of the supply reel and the period of

  rotation (or number of rotations) of the take-up reel.

  Yet another object of the present invention is to create a device for performing arithmetic operations and displaying the remaining amount of tape using the result obtained from the above discrimination

tape reel type.

  Other objects and features of the present invention

  tion will appear more clearly on reading the

  detailed description below, with reference to the drawings below

  annexed in which: FIG. 1 is a block diagram showing a

  embodiment of the device according to the present invention

  tion. Fig. 2 is a graph explaining the variation of the rotation period of a reel according to the type of strip reel. Figs. 3A and 3B are respectively graphs representing the sum of the periods of rotation of the supply coil and the take-up coil according to the type of

tape reel.

  Fig. 4 is a synoptic table showing the operation

  the remaining amount of tape.

  We start by calculating the period and the remaining duration of the tape of a coil disc using the equations indicated below. Using the symbols shown on the right side, in front of the following quantities: total length of the strip --- L length of strip wound on the take-up reel after t seconds --- L quantity of strip remaining on the supply reel after t seconds --- Q speed of the tape unwinding --- V thickness of the tape --- h maximum radius of the tape before the tape is unwound --- R radius of the tape wound on the reel supply after t seconds --- Rs radius of the strip wound on the take-up reel after t seconds RT period of rotation of the disc of the supply reel --- fi

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  period of rotation of the take-up spool disc fT radius of the spool hub --- r

  the following equations are obtained for the supply coil

  tation: ITR2 = r2 + hLA 1TR2 - WR 2 = hM RS = R2- t Similarly, with regard to the take-up coil, we obtain the following equation: Therefore, the sum F of the rotation period f of - s the supply coil and the rotation period fT of the receiving coil becomes: F = fs + fT

S T

= V (RS + RT)

v - 2 hV + + -

  On the other hand, with regard to the supply coil

  tation, nRS2 = Wr2 + hQ fS = V_ ir2 + Q

  and the amount of time T remaining from the power reel

  q tation can be written by the following equation (2): TV 'OEr2 T = Vhf2TUr --- (2) q 4hiTs hV Consequently, when the radius r of the coil hub and the rotation period fS of the disc the supply coil are known, one can get the remaining duration T of the q

amount of tape.

  An embodiment of the system for discriminating the type of tape reel according to the present invention will now be described with reference to FIG. 1. This embodiment makes it possible to know the radius r of the hub

  of the above coil and the amount of time remaining T -

q

  tape from the supply reel.

  A magnetic strip 10 is taken from a supply coil.

  tation 11 and wound on a take-up reel 12. The radius of the respective hubs 11a and 12a of the reels 11 and 12 differs according to the type of cassette containing said reels,

  the types of tape cassettes described above.

  The rotation of the coils 11 and 12 is detected by rotation detectors 13 and 14. The rotation detectors 13 and 14 can be of known construction, for example of the type in which a fluorescent light-emitting diode and a photo-transistor are mounted face face, and a rotary plate provided with sawtooth slots and fixed on the axis of rotation of the coil is inserted between the light emitting diode and the photo-transistor. The rotation detectors 13 and 14 produce forty-eight pulses at the output, one per revolution of the coils 11 and 12, that is to say for each revolution of the rotary plate

mentioned above.

  The output pulses of the rotation detectors 13 and 14 are sent to counters 15 and 16. The counters and 16 respectively count the clock pulses of constant frequency which are sent from an oscillator 17,

  until the number of pulses sent from detectors

  Rotation sensors 13 and 14 reach a predetermined value which is for example forty-eight pulses. When the clock pulses supplied by the oscillator 17 are counted until the number of pulses supplied by the rotation detectors 13 and 14 reaches forty-eight pulses for example, the counted value is a value which is proportional at the time necessary for the coils 11 and 12 to rotate. As a result, counters 15 and 16 are obtained from the respective output signals of the

  coil rotation periods II and 12.

  The output signals from the counters 15 and 16 are sent to multipliers 18 and 19 o the signals are multiplied by the respective and constant running speed of a strip in normal mode (for example 33.35 millimeters per second in the case of the NTSC system and 23.39 millimeters per second in the case of the PAL system) which is sent by a device 20 for adjusting the speed of the tape. Consequently, when the strip 10 runs at twice the normal running speed of the strip for example, conversions are carried out in the multipliers 18 and 19 so that the above value becomes identical

247 281 3

  at that where the tape is traveling at a normal running speed. Therefore, it is possible to obtain multipliers 18 and 19 of the respective signals of the rotation periods fS and fT of the supply coil 11 and of the take-up coil 12. The output signals of the multipliers 18 and 19 are sent to an adder 21 o the signals are added, and therefore a signal can be obtained which can be described by means of equation (1) above and corresponding to a rotation period (fS + fT) The output signal from the adder 21 is sent to a comparator 22 o the signal thus supplied to comparator 22 is compared to a predetermined threshold period according to the type of diameter of the hub of the tape reel. This threshold period is for example set to 12.1 seconds for the NTSC system and 17.2 seconds for the PAL system. When the signal sent to the comparator 22 is less than the threshold period, a discrimination is made and makes it possible to know that it is a tape cassette comprising reels whose diameter of the hub is 26 millimeters which is used, it is is to say

  a tape cassette of the type mentioned above T-120, T-

  , E-240, E-180 or E-120. On the other hand, when the signal sent to the comparator 22 is higher than the threshold period, discrimination takes place and makes it possible to know that it is a tape cassette comprising reels whose diameter of the hub is 62 millimeters which is used,

  i.e. a tape cassette of one of the men-

  mentioned above, namely: T-60, T-30, T-20, E-60, E-30 or E-20. The output of the comparator is sent to a cassette indicator 23 o is displayed the type of the tape cassette

  above or the hub diameter also shown above

  above. The principle which has just been described will now be repeated with reference to FIG. 2. When using a T-30 type tape cassette for example, the periods of

  rotation of the supply spool and the take-up spool

  time vary respectively with respect to time, as shown approximately by the solid lines I and II. If these periods of rotation represented by the solid lines I and II are added, the resulting sum of the periods of rotation appears in the form represented by the solid line III. As a result, and depending on the path taken by the strip, the rotation period of the supply reel becomes short (small) and the rotation period of the take-up reel becomes long (large), but the sum of the two periods of rotation is always practically at a constant value. Similarly, when using a T-60 type tape cassette, the periods of

  rotation of the supply spool and the take-up spool

  respectively vary with time, as roughly represented by the dotted lines IV and V. If these periods of rotation represented by the dotted lines IV and V are added, the resulting sum of the rotation period is in the form represented by the dotted line VI. Consequently, and depending on the path taken by the strip, the rotation period of the supply reel becomes short (small), and the period

  of the take-up reel becomes long (important

  aunt), but the sum of the two periods of rotation is always practically at a constant period. The value

  represented by the dotted line VI represented above

  above is more important than the value represented by the solid line III. These values represented by the line

  continues III and the dotted line VI are respective-

  compared to the threshold period and discriminated by

comparator 22.

  If one concentrates either on the supply reel or on the take-up reel, and the fact that the period of rotation varies according to the course carried out by the band, it is not possible to carry out a discrimination concerning the type of coil used. However, by adding the periods of rotation of the two coils according to the device of the present invention, the added value constitutes a substantially constant value but different depending on the type

  of coil used, which makes it possible to discriminate

  nation. Furthermore, when the above discrimination is carried out, an average value can be used between the two respective rotation periods of the two coils, without adding the rotation periods of the two coils. In this case, the above average value of a T-30 tape cassette is in the form of the dashed line VII in FIG. 2. The above average value for a T-60 type tape cassette is in the form of the dashed line VIII and it follows that discrimination between the two average values VII and VIII becomes possible. Furthermore, the number of rotations which is in reciprocal relationship with the

rotation period.

  The graph in fig. 2 linearly represents the variation of the rotation period, in order to simplify the

  description of the operating principle, but in the

  in reality the period of rotation of the coil varies non-linearly as a function of variations in the diameter of the strip wound on the coil. Consequently, the sum of the periods of rotation of the supply belt and of the take-up reel effectively varies in a non-linear fashion, as shown in FIGS. 3A and 3B. Fig. 3A shows the variation of the sum of the rotation periods of the two

  reels for types of tape cassettes T-20, T-30, T-

  , T-90 and T-120. On the other hand, fig. 3B shows the variation of the sum of the periods of rotation of the reels for tape cassettes of type E-20, E-30, E-60, E-120 and E-240. As clearly shown in Figs. 3A and 3B and although the sums of the coil rotation periods are actually non-linear, the respective sums of the different types of tape cassettes are presented with completely different values, and as a result the comparison of the threshold period and discrimination at comparator 22 can be done with ease

and certainty.

  If we go back to fig. 1, the output signals of the multiplier 18 and of the comparator 22 are respectively

  sent to an arithmetic operator 24. The arithmetic operator

  metique 24 performs an arithmetic operation described by equation (2) above. Consequently, the arithmetic operator 24 performs the arithmetic operations by considering the terms Vr-- and h as constants, and 4hiî hV fS2 as a variable in equation (2), and it produces an output signal which indicates the remaining amount of tape on the supply reel 11 as a time (i.e., a time indicating the minutes remaining during which recording and / or reproduction can

be performed).

  The output signal from the arithmetic operator 24 can be sent to an indicator 26 via an indicator control circuit 25 and the indicator 26 displays the remaining amount of tape as a duration, which is obtained as the result of

  the arithmetic operation above. Consequently, the use

  The CTR user can easily see the type of tape cassette he is using by looking at indicator 23, and he can also easily see the amount of tape remaining on the tape.

indicator 26.

  In addition, the display function of the type of tape cassette can be omitted by the indicator 23, which uses the compared result obtained from the comparator 22 to perform the arithmetic operation concerning the amount of tape remaining. The block diagram of fig. 1 shows an embodiment capable of carrying out the operations of the device according to the present invention, but when the above device is implemented, a part of this device can be produced which is surrounded by the dotted line of the fig. 1 using the functions of a micro-calculator. We will now describe with reference to the synoptic table of FIG. 4 discriminating the type of tape cassette, calculating the operation concerning the remaining amount of tape and the display operation of the above case. Operation begins at a step 30 and an initialization operation is carried out at step 31 where, for example, the display of the indicator is erased. In the next step 32, a judgment is made on the state of insertion of the tape cassette, and a judgment on the fact of knowing whether the device is in a mode of

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  operation is carried to step 33. A judgment is made on whether the reproduction mode is a normal reproduction mode or a reproduction mode at twice the normal speed, which is carried out in step 34 following. When the judgment result of step 34 is NO, that is to say when the reproduction mode is a normal reproduction mode, forty-eight pulses are counted for each rotation of the take-up reel 12 in step 35, and forty-eight pulses are counted for each rotation of the supply coil 11 in step 36. The periods of rotation of two coils obtained as a function of the value counted above are added up in step 37 which follows. On the other hand, when the result of the judgment

  step 34 is YES, that is to say when the mode of reproduction

  tion is a reproduction mode at a speed which is twice the normal speed, forty-eight pulses are counted in step 38 each time that the take-up reel 12 performs two rotations and forty-eight pulses are

  counted in step 39 each time the supply coil

  tation 11 performs two rotations. As a result, one can get a rotation period converted to a period

  corresponding to normal speed if the reproducing mode

  tion is a mode of reproduction where the speed is twice

  normal speed. As a result, the functions performed

  killed and described above are equal to those carried out

  by counters 15 and 16 and multipliers 18 and 19.

  The coil rotation periods obtained in steps 38

  and 39 are added in step 37.

  After adding the rotation periods of the two coils in step 37, a judgment is made at step 40 on whether the added value of the rotation periods obtained in step 37 is greater than 16.5 seconds. This step 40 corresponds to the comparator 22 which performs a

comparison operation.

  When the result of the judgment in step 40 is NO, that is to say when the sum of the periods of rotation of the two coils is less than 16.5 seconds, this indicates that the diameter of the hubs of the coils can be considered

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  as small. This means that the discrimination made shows that the tape cassette used is of the E-120 or E-180 type for example. In this case, steps 41j, 41i, 41h, 41b and 41a are carried out in succession, and the sum of the rotation periods are compared with each of the respective values of the predetermined rotation periods whose durations are 100 minutes, 90 minutes, 80 minutes, minutes and 10 minutes depending on the amount of tape

  remaining, at each of the above steps. When the result

  judgment status obtained by the above comparison is YES, the corresponding light emitting element (LED) is lit in the corresponding steps 42J, 42i, 42h, ---, 42b and 42a and the quantity of remaining strip is displayed under form of a duration which shows the remaining duration, that is to say in a rounded manner, 100 minutes, 90 minutes, 80 minutes, ---, 20 minutes or 10 minutes. When the amount of remaining tape expressed as a duration becomes less than 10 minutes, an indicator light lights up in step 43 to indicate that the amount of remaining tape is low; In addition, when the quantity of remaining tape expressed as a duration is greater than 100 minutes, it is not necessary to know the remaining duration with precision, and in this case a display indicating that the remaining quantity

is 100 minutes is displayed.

  On the other hand, when the result of the judgment made in step 40 is YES, that is to say when the sum of the period of rotation of the two coils is greater than 16.5 seconds, this indicates that the diameter coil hubs was found to be important. This means that the discrimination has established that the tape cassette which has been used is for example of the E-30, E-60 or E-90 type. In this case, steps 44i, 44h, 44g, ---, 44b and 44a take place in succession and the sum of the rotation periods are compared with each

  respective values of the predetermined rotation periods-

  mined with durations of 90 minutes, 80 minutes,

  minutes, ---, 20 minutes and 10 minutes, corresponding

  the remaining amounts of tape at each of the above steps. In the case where the result of the judgment obtained by the above comparison is YES, the corresponding LED light emitting element is lit in the corresponding steps i, 45h, 451, ---, 45b and 45a, and the duration corresponding to the quantity remaining band is displayed as the remaining time, which is expressed as 90 minutes, 80 minutes, 70 minutes, ---, 20 minutes, and 10 minutes. When the amount of remaining tape expressed as time is less than 10 minutes, an indicator light will light up in step 43 to indicate the low

remaining amount of tape.

  It goes without saying that the invention is not limited to the embodiments indicated and that various modifications and variants can be made to it without departing from its

scope.

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Claims (10)

  1. Device for discriminating or detecting types of tape reels, characterized in that it comprises a detection operation (13, 14, 15, 16, 35, 36, 38, 39) intended to detect periods of rotation respectively or numbers of rotations as a function of the respective rotation of a tape supply reel and a tape take-up reel; an addition operation (21, 37) for adding the rotation periods or the respective rotation numbers of the two coils obtained from said detection operation; and a comparison and discrimination operation (22, 40) for comparing the added value obtained by said addition operation and   to discriminate the diameter of the coil hub.   2. Device according to claim 1, characterized in that it further comprises an indicator operation (23) intended to display the type of tape reel according to the results of the discrimination obtained by said operation   of comparison and discrimination.   3. Device according to claim 1, characterized in that it further comprises an indicator operation (24 to 26; 41d to 41a; 42d to 42a; 41i to 44a; 45i to 45a) intended to display the remaining quantity of tape on said supply reel by converting the remaining amount of tape into time, according to the result of the discrimination   obtained from said comparison and discrimination step.   4. Device according to claim 1, characterized in that it further comprises an indicator operation (23) intended to display the type of tape reel according to the result of the discrimination carried out in said comparison and discrimination operation, and a indicator operation (24 to 26; 41d to 41a; 42d to 42a; 44i to 44a; 45i to a) intended to display the remaining amount of tape on said supply reel by converting the remaining amount of tape into time, depending on the discrimination results obtained from said comparison operation and of discrimination.   5. Device according to claim 1, characterized in that it further comprises an operation (34, 35, 36, 38, 39) intended to obtain the rotation period or the respective number of rotations of the two coils detected by said   detection operation so that the value obtained above   above is the same regardless of the speed of unwinding-   -5 ment of the tape, and to provide the result thus obtained to said addition operation.   6. Device for discriminating the type of coil to   strip, characterized in that it comprises: detection means   rotation torques (13, 14) intended to generate respective   pulsation as a function of the rotations of a tape supply reel and a tape take-up reel; counting means (15, 16, 17) for producing a rotation period output signal as a function of the   time required to count a predetermined number of im-   pulses supplied by said rotation detection means; adding means (21) for adding the respective signals of rotation periods relating to the rotations of the two above coils; and comparison means (22) for comparing the added value output by said addition means with a threshold   predetermined, and to produce a discrete output signal   nation according to the result of the comparison, this discrimination signal being a function of the type of the diameter of the hub of the coil.   7. Device according to claim 6, characterized in that it further comprises indicator means (23)   intended to display the types of the tape reel in function   tion of the output from said comparison means.   8. Device according to claim 6, characterized in   which it further comprises means of arithmetic operation   tick (24) intended to produce an output signal indicating the remaining amount of tape on the supply reel obtained from the output of said comparator means in the form of duration, and indicator means (26) intended to display the remaining amount of tape as a duration as a function of the output signal from said arithmetic operation means. 9. Device according to claim 6, characterized in that it further comprises indicator means (23) ú472813   for displaying the type of tape reel according to the output provided by said comparator means, arithmetic operation means (24) for producing an output signal indicating the amount of tape remaining on the supply reel obtained from the output of said comparator means in the form of duration, and indicator means (26) intended to display the remaining quantity of tape in the form of duration as a function of the output signal supplied by   said arithmetic operation means.   10. Device according to claim 6, characterized in that it further comprises multiplier means (18, 19, 20) intended to multiply a coefficient corresponding to the speed of the strip with the output of said counting means, and of send the resulting output to said means addition.