JP2961861B2 - How to measure the recording time of a cassette tape - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording time measuring method for automatically calculating a recording time of a cassette tape in a cassette tape recorder.

2. Description of the Related Art Conventionally, a cassette tape recorder does not automatically calculate the recording time of a cassette tape, and a cassette tape running time calculation method as shown in FIGS. 4 to 7 has been used. Hereinafter, the method will be described.

That is, as shown in FIG. 4, when the radius of the hub is R ₀ , the thickness of the tape is d, and the tape is wound n times on the take-up reel,
When the magnetic tape is that the vehicle is running at a constant speed V ₀ in the x-direction, the running time t from winding start to date can be indicated by equation (1).

t = An ² + Bn (1) Here, A = πd / V ₀ , B = 2πR ₀ / V ₀ , and in an actual cassette tape, the apparent thickness depends on the accuracy of the magnetic tape, uneven winding, and the like. d has a large error. Since this error differs depending on the cassette tape, it is necessary to correct each error. Therefore, (1) If the n is differentiated by t in formula, the rotational speed V _R of the take-up reel can be represented by the equation (2).

At this time, assuming that the rotation speed V _R of the take-up reel immediately after resetting the counter that counts the number n of windings of the take-up reel is V _RR , the thickness d of the tape is extremely thin, about 18 μ or less, and the radius of the hub is Since R ₀ is approximately 11 mm and the number of turns n is 1, 2An << B.

Therefore, the value B _R of the constant B immediately after reset from equation (2) can be obtained by the following expression.

Also, the value A _R of the constant A after reset is given by the following equation (2). Can be obtained as

Therefore, when you want to find the transit time of the tape, performs a reset process (3) obtains a B _R from equation determines the A _R than using the value of the counter for counting the number of turns n after reset (4), ( The travel time is obtained by performing the calculation shown in equation (2). Further, even when the tape is reset in the middle of the tape, the running time from the reset position can be obtained.

FIG. 5 is a block diagram showing a conventional example for obtaining the running time of a cassette tape based on the above contents. In the drawing, 1 is a supply side reel, 2 is a take-up side reel, 3 is a magnetic tape, 4a and 4b are guides, 5 is a cassette tape, 6
Is a reel rotating shaft on the take-up side, and 7 is a detecting element that magnetically, optically or mechanically detects the rotating body 8 attached to the reel rotating shaft 6 and the mark of the rotating body 8 and outputs a rotation detection pulse. 9 is a rotation detection unit, and the period of the rotation detection pulse is directly proportional to the rotation period of the take-up reel 2. Reference numeral 10 denotes a rotation speed detection unit for detecting a rotation speed by inputting the rotation detection pulse, 11 a rotation counting unit for counting the rotation pulse of the reel 2 on the winding side of the cassette tape, and 12 a time when the cassette tape 5 is set or when the magnetic tape is set. In the middle of 3, a zero reset unit for resetting the rotation counting unit 11 to zero, and 13 is a formula (3),
(4) A _R was calculated by the equation, the travel time calculating unit that calculates the travel time up to the present by substituting B _R from the time of reset processing, 14 tape running inversion control section for inverting the cassette tape running direction, 15 A tape end detecting unit 16 detects the end of the cassette tape and notifies the tape running reversal control unit, and a heading control unit 16 feeds the tape to a recordable position on the magnetic tape in order to avoid the leader tape.

With the above configuration, the running time of the magnetic tape could be obtained by the method shown in the flowchart of FIG.

That is, when the cassette tape is set in step 1, the count value of the rotation counting unit 11 is set to zero by the zero reset unit 12. In step 2, when the take-up reel 2 rotates and the magnetic tape 3 is supplied, the reel rotating shaft 6 rotates and the rotating body 8 also rotates, and the rotation detector 7 outputs a rotation detection pulse proportional to the rotation cycle. Is output, so enter this. Step 3 In the rotation detection pulses input in step 2 on the basis, for detecting the rotational speed V _R of the take-up reel by the rotational speed detector 10. In step 4, it is determined whether or not the rotation of the rotating body 8 is the first time after the reset. If it is the first time, the process proceeds to step 5, and if it is the second time or more, the process proceeds to step 7. In step 5, the running time calculation unit 13 calculates the rotation speed V _RR obtained by the rotation speed detection unit 10 based on the first rotation detection pulse of the take-up reel 2.
(3) for storing seeking B _R from the equation. In step 6, the count value n is set to 1 by the rotation counting unit 11. In step 7, every time a pulse signal output from the rotation detector 7 is counted by the rotation counting unit 11, one is added to the count value n. In step 8, the running time calculation unit 13 detects the rotation speed V _R detected by the rotation speed detection unit 10 at that time,
The value B _R which is stored in search by the count value n and the step 5 of the rotary counting unit 11 obtains the A _R by performing calculation shown in equation (4). In step 9, the calculation shown in (2) is performed by the running time calculation unit 13 based on the values A _R , B _R , n thus obtained, and the running time t of the magnetic tape is calculated.
Is calculated. In step 10, the tape end detector 15 determines whether the magnetic tape has reached the end. If the end has been reached, the process is terminated. If not, the process returns to step 2 to repeat the calculation of the running time t.

Next, a method of obtaining the recording time of a cassette tape using the above-described conventional method will be described. In FIG.
In step 21, it is determined whether or not the function for detecting the recording time of the cassette tape has been selected. If it has been selected, the process proceeds to step 22, and if not, the process is temporarily terminated. In step 22, the take-up reel 2 is driven to fast-forward the tape. In step 23, the tape end detection unit
It is determined whether or not the end of the tape has been reached by 15. If the end has been reached, the process proceeds to step 23, and if not, the process returns to step 22 to continue the fast-forward of the tape. Step 24
Then, the count value of the rotation counting unit 11 is set to zero by the zero reset unit 12, and the running time t of the tape is obtained by the method shown in FIG. 6 while rewinding the tape. In step 25, the tape end detecting unit 15 determines whether or not the entire tape has been wound and has reached the end.If the end has been reached, the process proceeds to step 26.If not, the process returns to step 24 to rewind the tape. The calculation of the running time t is performed while continuing. In step 26, the recording time of the cassette tape is obtained by subtracting the time of the leader tape from the running time t when all the tapes have been wound. In step 27, the start of the magnetic tape is performed as preparation for starting recording.

Since the CD players were developed, it has been common practice to record signals recorded on an optical disc on a cassette tape. At this time, it is usual to perform a track editing operation in order to record the sound without interruption at the end of the A side or the B side of the cassette tape. There are already CD players that automatically perform this editing operation if you enter the recording time of a cassette tape. Further, there is a demand for a cassette tape recorder capable of automatically detecting the recording time and outputting data of the recording time to a CD player. Therefore, the above-described conventional method for automatically detecting the recording time uses the running time calculation method.

However, if only the recording time displayed on the commercially available tape is detected in the flow as shown in FIG. 7, it can be realized without taking a complicated configuration such as the conventional running time calculation. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of automatically detecting the recordable time of a cassette tape by performing a simple operation with a simpler configuration than in the prior art.

Means for Solving the Problems In order to achieve the above object, the present invention provides a rotation detection unit that outputs a rotation detection pulse of a take-up reel or a supply reel of a cassette tape, and a rotation counting unit that counts rotation pulses. A tape running reversing control unit for reversing the cassette tape running direction, a tape end detecting unit for detecting the end of the cassette tape and sending a signal to the tape running reversing control unit, and a rotation counting unit for detecting the end of the cassette tape. A zero reset unit for zero resetting the tape, a cueing control unit for sending the tape to a recordable position on the magnetic tape, a hub diameter data storage unit for recording a plurality of types of hub diameter data obtained in advance, and a cassette tape recording time. Recording time data storage unit that stores the range data of the rotation count value corresponding to, and runs the cassette tape from the beginning to the end A recording time calculation unit that calculates the cassette tape recording time by comparing the count value of the rotation counting unit at the time of the recording with the value stored in the recording time data storage unit, and performs a cueing by a cueing control unit. During this process, the hub diameter is determined by comparing the value counted by the rotation counting section with the data stored in the hub diameter data storage section.

When the function for detecting the recording time of the cassette tape is selected by the above-described configuration, the tape is fast-forwarded, all the tape is wound on the winding reel, and then the tape is rewound while being rewound. The number of rotations of the side reel is counted, and the number of rotations when the tape is wound from end to end is obtained. Next, the tape is run at a constant speed to perform the cueing of the tape. At this time, the count value of the number of rotations of the take-up reel is compared with the value stored in the hub diameter data storage unit to determine the hub diameter. Is determined. By comparing the data of the recording time data storage unit corresponding to the hub diameter with the rotation speed when the previously obtained tape is wound from end to end, it is determined which recording time is within the range, The recording time of the tape can be determined.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a graph showing the relationship between the number of revolutions N of a take-up reel when the tape is wound from end to end and the recording time indicated on a commercially available cassette tape. If the rotation speed N of the take-up reel can be detected from this graph, the recording time of the cassette tape can be obtained.
However, for example, when the rotational speed N is in the range of a to b in FIG. 2, it cannot be determined whether the cassette tape can record for 40 minutes or 46 minutes. This is because the diameter of the hub of the cassette tape is not one type. As shown in FIG. 2, the graph of the thick hub becomes a thick line, and the graph of the thin hub becomes a thin line. Therefore,
In order to determine the recording time of the cassette tape using FIG. 2, it is necessary to determine the hub diameter. Therefore, a method for determining the hub diameter will be described. Constant speed from end of tape
When it was run tape between t ₀ at V _0, a (1) from the _{equation, V 0 t 0 = 2πn (} R 0 + dn / 2) ...... (5). If n is sufficiently small, the second on the right side of the equation (5)
Since the term can be ignored, n = V ₀ t ₀ / 2πR ₀ (6), and the tape is run at a constant speed for an appropriate time t ₀ , and the rotation speed n of the take-up reel at that time is detected. For example, different n can be obtained for different hub diameters _R0 .

Therefore, values corresponding to a and b in FIG. 2 are used as range data of the rotation number count value corresponding to the recording time of various cassette tapes, and several types of hub diameter data are represented by n in Expression (6).
Is stored, the recording time of the cassette tape can be obtained.

In FIG. 1, 21 is a supply reel, 22 is a take-up reel, 23 is a magnetic tape, 24a and 24b are guides, 25 is a cassette tape, 26 is a take-up reel rotating shaft, and 27 to 29 are conventional examples. A rotation detector, a rotating body, and a detecting element having the same function. 31 and 32 have a rotation counting unit and a zero reset unit having the same function as the conventional example. A control unit, a tape end detection unit, and a cueing control unit; 38 is a hub diameter data storage unit that stores several types of hub diameter data obtained in advance to determine the hub diameter, and 39 is a recording time that stores a range data of a rotation number count value corresponding to a recording time of various cassette tapes. The data storage unit 37 compares the count value of the rotation counting unit 31 when the cassette tape is run from one end to the other with the value stored in the recording time data storage unit 39, and calculates the cassette tape recording time. This is a recording time calculation unit for calculating.

The operation of the embodiment of the present invention configured as described above will be described with reference to the flowchart of FIG.

In FIG. 3, steps 1 to 3 are the same as the operations of steps 21 to 23 in the conventional example, and the description is omitted. In step 4, the count value of the rotation counting unit 31 is set to zero by the zero reset unit 32. In step 5, the tape is rewound, and the pulse signal output from the rotation detector 27 is counted by the rotation counting unit 31.
In step 6, it is determined whether or not the end of the tape has been reached by the tape end detecting unit 35. If the end has been reached, the process proceeds to step 7, and if not, the process returns to step 5 to count the rotation number of the take-up reel. to continue. In step 7, the count value of the rotation counting unit 31 is set to zero by the zero reset unit 32, and the rotation number count value is stored as N. In step 8, the magnetic tape is caught as a preparation for starting the recording, and the rotation counting section is started.
The pulse signal output from the rotation detector 27 is counted by 31. In step 9, it is determined whether or not cueing of the magnetic tape for running the tape at a constant speed for a predetermined time has been completed. If completed, the process proceeds to step 10, and if not completed, the process returns to step 8 to return to the take-up reel. Continue counting revolutions. In step 10, the recording time calculation unit 37 compares the rotation count value at the end of the cueing with the value stored in the hub diameter data storage unit 38 to determine the hub diameter, and corresponds to the hub diameter. Recording time data storage unit 39
Is compared with the rotation number count value N stored in step 7 to determine which range N is in, and obtain a recording time corresponding to N.

As described above, according to the present embodiment, even if the cassette tape is not completely wound, and is mounted on the cassette tape recorder, the rotation count value N of the winding-side reel 22 from end to end of the tape is detected. Further, the rotation number count value n of the take-up reel 22 at the time of performing the cueing of the magnetic tape is obtained, and is compared with the data stored in the hub diameter data storage unit 38 to count. The hub diameter is determined by determining which hub diameter the value falls within. Then, the data group stored in the recording time data storage unit 39 corresponding to the hub diameter is compared with the rotational speed count value N, and the range of N is determined to determine the recording time corresponding to N. Can be.

In this embodiment, the recording time is obtained by counting the number of rotations of the take-up reel. However, the recording time can also be obtained by counting the number of rotations of the supply reel.

Effects of the Invention As described above, according to the present invention, the count value of the rotation counting unit when the cassette tape is run from the beginning to the end and the value stored in the recording time data storage unit are compared, and the cassette tape is compared. A recording time calculation unit for calculating the recording time of the head, and compares the value counted by the rotation counting unit with the data stored in the hub diameter data storage unit while performing the cueing by the cueing control unit. The hub diameter is determined by finding the range of the hub diameter in the hub diameter data stored in the hub diameter data storage unit, thereby determining the hub diameter. With a simple configuration, the recording time of the cassette tape can be automatically obtained without performing a very complicated operation.

[Brief description of the drawings]

FIG. 1 is a block diagram of a method for measuring the recording time of a cassette tape according to one embodiment of the present invention. FIG. 2 is a characteristic diagram showing the relationship between the number of revolutions N and the recording time indicated on a commercially available cassette tape. FIG. 3 is a flowchart for calculating the recording time of a cassette tape of the apparatus, FIG. 4 is a plan view showing the relationship between a magnetic tape and a take-up reel, and FIG. 5 is a conventional method for measuring the recording time of a cassette tape. And FIG. 6 and FIG. 7 are flow charts of measurement by a conventional method for measuring the recording time of a cassette tape. 21 ... supply side reel, 22 ... take-up side reel, 23 ... magnetic tape, 25 ... cassette tape, 27 ... rotation detection unit,
29: detection element, 31: rotation count unit, 32: zero reset unit, 34: tape running reversal control unit, 35: tape end detection unit, 36: cueing control unit, 37: recording time Arithmetic unit, 38: hub diameter data storage unit, 39: recording time data storage unit.

Claims (1)

(57) [Claims] 1. A rotation detecting section for outputting a rotation pulse of a take-up reel or a supply reel of a cassette tape, a rotation counting section for counting the rotation pulse, and a tape running reversal control for reversing the cassette tape running direction. A tape end detecting unit that detects the end of the cassette tape and sends a signal to the tape running reversal control unit, and a zero reset unit that resets the rotation counting unit to zero when the end of the cassette tape is detected. A cueing control unit that sends the cassette tape to a recordable position, a hub diameter data storage unit that records a plurality of types of hub diameter data obtained in advance, and a rotation count value corresponding to a recording time of the cassette tape. A recording time data storage unit for storing range data, and the rotation when the cassette tape is run from the start to the end. A recording time calculation unit that calculates the recording time of the cassette tape by comparing the count value of the counting unit with the value stored in the recording time data storage unit, and performs cueing by the cueing control unit. A method for measuring the recording time of a cassette tape, comprising comparing the value counted by the rotation counting section with the data stored in the hub diameter data storage section during execution to determine the hub diameter.