JPS6252389B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic recording/reproducing device that is capable of displaying a tape running amount that changes linearly with respect to the tape moving amount. Conventionally, the tape counter of a magnetic recording/reproducing device is
The rotation of the take-up reel stand or the supply reel stand was detected as a measure of the amount of tape wound, and the number of revolutions of the reel stand was counted. Therefore, since the counted amount changes non-linearly with respect to the actual tape movement amount, an accurate tape movement amount cannot be displayed and the utility value is low. The ideal system for a tape counter would display the running time of the tape. This is a so-called linear counter, and in the case of reel-to-reel devices, a rotating pulley is installed on the tape running path, and the rotating pulley rotates to follow the movement of the tape, thereby counting the number of revolutions of the rotating pulley. Although a linear counter can be easily constructed, it is extremely difficult to provide a rotating pulley that rotates to follow the running of the tape in a cassette-type device.For this reason, it is difficult to construct a linear counter with a cassette-type device. is very difficult. In view of the above-mentioned conventional situation, the present invention has been developed to enable a cassette-type device to be easily equipped with a linear counter.One embodiment of the present invention will be described below with reference to the drawings. 1 is a supply reel stand, 2 is a take-up reel stand, and rotation speed detectors 3 and 4 are provided to detect the rotational speed of each of these reel stands 1 and 2. The rotational speed detectors 3 and 4 are composed of magnets and magnetically sensitive elements magnetized at equal intervals on the outer periphery that rotates integrally with the respective reel stands 1 and 2, and detect the rotational speed of the respective reel stands 1 and 2. Outputs angular velocity from pulses with a frequency corresponding to . Note that the detectors 3 and 4 may also be constructed of a disk having holes at equal intervals that rotates together with the reel stands 1 and 2, a light source, and a light receiving section. 5 and 6 are reel hubs mounted on the reel stands 1 and 2, and 7 is a reel hub 5 and 6 with both ends thereof
The tape is fixed to and wound around the tape, and is guided by guide rollers 8 and 9 to travel. The tape 7 is run at a constant speed by a capstan and a pinch roller (not shown) during recording or reproduction, and is wound and run by the reel stand 1 or 2 during rewinding or fast forwarding. Now, when tape 7 is running at speed V,
Reel stand 1 detected by rotation speed detectors 3 and 4,
2 rotation speed is ω _S ω _T , the radius of the reel hubs 5 and 6 is R _O , the tape winding radius when the tape 7 is completely wound on one reel hub 5 or 6 side is R F , and the tape winding radius is R _F If the tape winding radius of the reel hub 5 is R _S at this time, and the tape winding radius of the reel hub 6 is R _T at this time, R _S ² + R _T ² = R _O ² + R _F ² ... (1) Also, V = R _S・ω _S =R _T・ω _T ...(2) From these equations (1) and (2), From this equation (3), the tape speed V can be easily derived through calculation processing by finding ω _S ·ω _T . However, in this case, the values of R _O and R _F are also required, which will be described later. Next, the calculation for determining the tape speed V from the rotational speeds ω _S and ω _T of both reel stands 1 and 2 will be explained using FIG. 10 is a multiplication circuit which inputs ω _S and ω _T from the speed detectors 3 and 4 and outputs ω _S and ω _T. Further, 11 and 12 are square circuits, which output ω _S ² and ω _T ² in response to inputs ω _S and ω _T , respectively. 13 is _{an adder} circuit ^that calculates ( ^ω _S ²
+ω _T ² ). 14 is a division circuit;
(ω _S ² +ω _T ² ) is input and its reciprocal (1/ω _S ² +ω _T ² ) is output. Further, 15 is a reference signal generator, which outputs a constant K based on the above-mentioned (R _O ² +R _F ² ). 16 is a multiplication circuit,
Using the output (1/ω _S ² +ω _T ² ) of the dividing circuit 14 and the output K of the reference signal generator 15 as input, (K/
ω _S ² + ω _T ² ), and this output is input to the 1/2 power circuit 17.

[Formula] is output. This output and the output of the multiplication circuit 10 ω _S・ω _T
is input to the multiplication circuit 18, and the output is V, that is,

[Formula] is output. Here, K is (R _O ² +R _F ² ). In the case of a tape cassette, the tape speed during recording or playback is generally 4.75cm/S, and if this value is V _P , V/V _P is calculated every second, added during fast forwarding and recording/playback, and subtracted when rewinding. By displaying the calculation result on a counter, a linear counter can be obtained. Next, how to obtain R _O and R _F will be explained. For example, as shown in FIG. 3, the tape counter is set by operating the counter set button, and at the same time a tape rewind command is generated to bring the tape into the tape rewind state. When all the tapes 7 are wound onto the supply reel stand 1, both the supply reel stand 1 and the take-up reel stand 2 stop rotating, and the detectors 3, 4 or another detects that the end of the tape has been reached. Based on the detection, a reproduction command is generated and a tape reproduction state is entered. At the same time, the speed detectors 3 and 4 detect the speeds ω _SO and ω _TO of the tape 7 at the start of running based on the detection command, and the values are stored in the memory based on the memory command, and then the tape 7 is brought to a stopped state based on the stop command. becomes. The series of operations from the time the counter set button is pressed until the tape running is stopped is programmed by the microcomputer to be performed continuously. ω _S stored in the above memory
_O ·ω _TO is immediately subjected to arithmetic processing. That is, R _O・ω _TO =V _P ...(4) R _F・ω _SO =V _P ...(5) From equations (4) and (5), R _O =V _P /ω _TO , R _F = V _P /ω _SO ...(6), and K=R _O ² + R _F ² = (1/ω _TO ² +1/ω _SO ² )V _P ² ...(7) is calculated, and therefore the reference signal The generator 15 is ω
When _TO・ω _SO is input, the value of K is automatically calculated and the calculation result is output. The above equation (3) can also be transformed as follows. Substituting equation (6) into this, we get becomes. In the above equation (9), V _P is a constant value of 4.75 cm/S, and the square root is ω _S ²・ω _T ²・ω _SO
²・_ωTO It is only necessary to calculate ^2. Therefore, as soon as _ωSO・_ωTO is detected at the beginning of the tape, the tape counter display is reset to zero, and after that, V is added every second during recording, playback, and fast forwarding. good. Minutes and seconds can also be displayed using the sexagesimal system. Here, in the detection of ω _SO and ω _TO , there is a risk that the initial value will be erroneously detected, and therefore the initial value is not preferable. The more ω _SO and ω _TO can be detected at the correct value and at a position close to the beginning of the tape, the better. A method for this purpose will be explained using FIG. 4. FIG. 4 shows one side of the speed detector 3. The output of the speed detector 3 is input to the delay circuit 19 and the subtraction circuit 20, and the subtraction circuit 20 uses the newly input value and the delay circuit. The value before 19 is subtracted, and if the subtracted value is zero or a preset value, that is, the same rotational speed is detected twice, that value is stored in the memory 21 as _ωSO . On the other hand, on the speed detector 4 side, ω _TO is memorized in a similar manner, and the tape is stopped at the same time as the memorization of these ω _SO and ω _TO is completed. This allows us to obtain the correct ω _SO and ω _TO . Note that the above ω _SO and ω _TO can also be set, for example, by tape running time for convenience, and the detection output 2 seconds after the start of tape running may be stored as ω _SO and ω _TO . As described above, the present invention sets a reference signal based on the output of the rotational speed detector at the beginning of the tape, and uses an arithmetic circuit to calculate this reference signal and the output signal of the rotational speed detector while the tape is running. The output signal of this is used as a tape counter display signal. According to this, the tape counter display can be displayed not only during recording and playback, but also during tape fast forwarding and rewinding. The initial objective has been achieved and the effects are significant. Moreover, the counter can be used as a linear counter for time display regardless of the total tape length and tape thickness.

[Brief explanation of the drawing]

FIG. 1 is a top view showing a tape running section in an embodiment of the present invention, FIG. 2 is a block diagram showing the same arithmetic circuit, and FIGS. 3 and 4 each explain the operation for obtaining a reference signal. This is a diagram for 1, 2... Reel stand, 3, 4... Speed detector,
5, 6...Reel hub, 7...Tape, 11,1
2... Square circuit, 13... Addition circuit, 14... Division circuit, 15... Reference signal generator, 16... Multiplication circuit, 17... 1/2 power circuit, 18... Multiplication circuit.

Claims (1)

[Claims] 1. A tape having both ends fixed to a reel hub;
two reel stands to which the reel hub is attached;
a rotational speed detector that detects the rotational speed of each of the reel stands, a reference signal set based on the output of the rotational speed detector at the tape starting end, and an output signal of the rotational speed detector during tape running. 1. A magnetic recording and reproducing apparatus comprising: an arithmetic circuit that calculates a tape speed signal by calculating a tape speed signal; and an output of the arithmetic circuit is configured to be a tape counter display signal. 2. The magnetic recording and reproducing apparatus according to claim 1, wherein the reference signal is obtained based on the output of a rotational speed detector in a state where the tape reaches the beginning of the tape from the tape rewinding state and is reproduced from the beginning of the tape. . 3. It is characterized in that when the rotational speed signal of the rotational speed detector at the tape starting end is twice the same signal or the second signal is a signal within a preset tolerance range, that value is used as the reference signal. A magnetic recording base generation device according to claim 1 or 2.