JPS59144088A - Arithmetic method for tape remaining quantity - Google Patents

Abstract

PURPOSE:To calculate the time of tape remaining quantity by using a device to detect the number of revolutions of a hub. CONSTITUTION:The tape length L is calculated 107 as L=2pin (r+n.t/2), where (n) is the total number of revolutions of a driving shaft 101 of a hub at the rewind position, (t) is the thickness of a tape and (r) is the outer diameter of the hub respectively. Then the time R of tape remaining quantity is calculated 107 as R=Rm.(Lm-L)/Lm, where Rm means the maximum record time of a single side of the tape and Lm is the maximum length of the single side of the tape. Then the time R is displayed 105.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a cassette tape recorder, a cassette player,
Cassette device 4. The present invention relates to a method for calculating the remaining amount of tape in a cassette device such as a VTR, and particularly relates to a method for calculating the remaining amount of tape in which the remaining amount of tape can be calculated using the total number of rotations of a hub from the rewind position.

BACKGROUND ART A cassette device has a counter for displaying the tape position of a cassette tape. This counter uses the principle of the Geneva mechanism, or uses a pickup coil type detector, an optical pulse generator, etc., to indicate the hub rotation amount of the take-up hub (or the supply hub). The tape position is displayed by the amount of rotation. However, in such a tape position display method, since the count value of the counter is not proportional to the open length wound around the take-up hub or the tape running time, it is not possible to accurately display the remaining amount of tape.

For this reason, there have been cases where a song or video that was expected to be recorded on one side is unexpectedly long and cannot be recorded completely, resulting in the ending being cut off.

Recently, counters called real-time counters have been developed that detect the number of rotations of the left and right hubs, calculate and display the remaining tape time using a computer, and are now installed on cassette decks.

However, such real-time counters require two detection devices to detect the rotational speed of the left and right hubs, resulting in high costs, and they cannot display the remaining time etc. unless the hubs are actually rotated. (displayed after 4-5 seconds) was not desirable.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a tape remaining amount calculation method that can calculate the tape remaining amount time by simply providing one detection device for detecting the rotational speed of the hub.

Another object of the present invention is to provide a method for calculating the remaining tape amount by simply inputting the name of the cassette tape set on the deck without rotating the hub.

DISCLOSURE OF THE INVENTION The present invention calculates the tape length from the total number of rotations n of the hub from the rewinding position, the thickness t of the tape, and the outer diameter r of the hub using the following formula % formula % ( In short, calculate the remaining time R of the tape from the maximum recording time Rm for one side and the maximum tape length Lm for one side using the following formula % formula % (), or calculate the time T required for one revolution of the hub. Calculate the tape length using the time T and tape feed speed V using the following formula % formula (9), and use the tape length to calculate the remaining tape time from formula (2). It is.

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of stored contents.

In FIG. 1, 101 is the hub drive shaft on the winding side, 102
103 is a pulse generator that generates two-phase pulses Pa and Pb having a phase difference of 90 degrees each time the hub drive shaft rotates by a predetermined amount; 103 monitors the phases of the two-phase pulses Pa and Pb to determine the rotation direction; This is a rotation direction discrimination circuit that detects the pulse Pa
If the phase of pulse Pb is 90° ahead of the phase of pulse Pb, positive pulse +P is assumed to be rotating in the normal direction, and if the phase of pulse Pa is 90° behind the phase of pulse Pb, the pulse is reversed. As a negative pulse-P
occur respectively. It is assumed that M pulses Pa and Pb are generated per rotation of the hub drive shaft. Reference numeral 104 denotes a reversible counter, and a first counter with a capacity M that counts up 10 positive pulses P generated at every predetermined angle rotation in the positive direction and counts up negative pulses -P generated every predetermined angular rotation in the negative direction. 104a and the first counter 104
It has a second counter 104b that counts up the carry pulse OFF generated from a and counts down the carry pulse BRP generated from a, and stores the tape running position by both counters. Note that the count value of the second counter 104b indicates the hub rotation speed. 105 is a display section that selectively displays the tape running position (hub rotation amount) and remaining tape time, which are the contents of the second counter 104b; 106 is a display drive circuit; 107
is a microcomputer, and includes a processing device 107a,
A control program memory 1ayb't for storing a control program, a RAM (random access memory IJ) 107C, a hub radius r, and a tape thickness t.

It has a parameter memory 107d that stores reproduction and recording tape speed V, a correspondence table of maximum recording time Rm - single-sided tape length Lm, and the like. For example, as shown in FIG. 2, the RAM 107c has storage areas MO1 to MO1 corresponding to tape identification numbers 01 to 99 that identify each cassette tape.
M99 is provided, and each storage area stores the tape running position of the corresponding cassette (total hub rotation amount n from the tape rewinding position)
, maximum recording time Rm, etc. are stored. Furthermore, RAM
107C is constituted by a battery-backed RAM, and if battery backup is not used, it is necessary to separately provide a non-volatile memory for storing the contents of the RAM 107C when the power is turned off. The processing device 107a performs data exchange processing with the operation panel described later, as well as
Performs tape remaining amount calculation processing. That is, the processing device 107a
When the remaining time display button on the operation panel (described later) is pressed, Lm2r is displayed at predetermined intervals (a) during stop, fast forwarding, and rewinding.
n(r+-;-n), (1) (however,
n is the total rotation amount of the hub shaft from the rewinding position, r is the hub radius,
t is the tape thickness) to calculate the length of the tape wound on the take-up hub (tape running length), and then the following formula % Formula % (2) (However, Lm is the maximum tape on one side) (Rm is the maximum recording time for one side), calculate the remaining tape time R. (b) During recording and playback, use the following formula (%) (However, ■ is the recording or playback speed, and T is the time required for one revolution of the hub shaft.) From this, calculate the tape running length, and then ( 2) Calculate the remaining time R of the tape from the equation number.

108 is a switching circuit which outputs the remaining tape time R to the display drive circuit 106 when a remaining time display button (to be described later) is pressed, and outputs the count value of the second counter 104b when a counter button is pressed. n is output to the display drive circuit 106.

Reference numeral 109 denotes an OR gate, which allows the carry pulse OFF and carry down pulse BRP generated from the first counter 104a to pass through. 110 is a J-type flip-flop which is alternately set/reset by the output pulse of 109 (every rotation of the hub drive shaft); 111 is a J-type flip-flop that measures the time during which the flip-flop 110 is set; The timer starts counting time when the flip-flop 110 is set, and stops counting when it is reset.

112 is an operation panel having switches, - keys, etc. On the operation panel 112, there are a stop button 112a, a record button 112b, a rewind button 112C, a play button 112d, a fast forward button 112e, a pause button 112f, and a deck. Identification number of the cassette tape to be loaded, set side A/B
Information inputted from the numeric keypad 112g for inputting the type of side, etc., the entry key 112h- for inputting the identification number and set side information into the microcomputer 107 by pressing after the tape identification number and set side are input, and the numeric keypad 112g. A display section 112I that displays
12j, a group of lamps 112m that displays the maximum recording time of the tape mounted on the deck, a lamp or buzzer (referred to as a lamp) 112n that prompts input of the recording time, and a display unit 105 that displays the amount of rotation of the hub shaft. A counter button 112p that is pressed to display the remaining tape time on the display section 105, a remaining time display button 112q that is operated to display the remaining tape time on the display section 105, a counter reset button 112r, etc. are provided.

Note that the display section 105 is provided on the operation panel 112.

Next, the present invention will be explained in detail. It is assumed that each storage area of the RAM 107C stores the total rotational speed n of the hub shaft from the rewinding position of the cassette tape to the current traveling position, the maximum recording time Rm, etc. corresponding to the storage area.

When side A of a cassette tape with the tape identification number "15" is mounted on the deck and "15A" is entered from the numeric keypad 112g, "15A"' is stored in an input register (not shown) and is also displayed on the display section 1121. be done.

Next, press the entry key 112h'i to display the tape identification number and set side "1" stored in the input register.
5A" is read by the processing device 107a and set in the built-in general-purpose register 107a'. Thereafter, the processing device 107a reads the total hub shaft rotation speed n and the storage area corresponding to the tape identification number "15" in the RAM 107C. The maximum recording time Rm is read into the general-purpose register 107a' and set in the hub shaft rotation speed nf reversible counter 104.

The processing device 107a determines which of the counter button 112p and the remaining time display button 112q is pressed, and if the counter button 112p is pressed, outputs an odor signal to the switching circuit 108 and stores it in the reversible counter 104. The device 107a outputs a switching signal to the switching circuit 108 to display the total hub shaft rotation speed n stored in the second counter 104b on the display unit 105, and displays the total hub shaft rotation speed n stored in the second counter 104b. Using the number n, the hub radius r stored in the parameter memory 107d, and the tape thickness t, equation (1) is calculated to calculate the length of tape travel from the rewind position.

Next, the maximum tape length Lm f for one side is determined from the correspondence relationship between maximum recording time and maximum tape length, and the remaining tape time R is calculated from equation (2) using L, Lm, and Rm, and the switching circuit 10
8 to the display drive circuit 106, and the display unit 105
to be displayed.

In this state, press the rewind button 112C or the fast forward button 112e.
When rewinding or fast forwarding is performed by operating 'i', the hub drive shaft 101 rotates at a high speed to rewind the tape or fast forward the tape.

Now, if the hub drive shaft 101 rotates, the pulse generator 10
2. The number of pulses Pa, P proportional to the rotation amount ζ
b are generated, and these are input to the rotation direction determination circuit 103. The rotation direction discrimination circuit 103 discriminates the phases of the pulses Pa and Pb, and if the rotation is normal (fast forwarding), one set of pulses P is detected.
One positive pulse Pf is output for each pulse a and Pb, and one negative pulse -P is output for each set of pulses Pa and Pb if rewinding is performed. Note that the frequencies of the plus pulse 10P and the minus pulse -P are equal to the frequencies of the pulses Pa and Pb. The plus pulse +P or the minus pulse -P is the first counter 104a, respectively.
A carry pulse (6-1 buffflow pulse) OFF and a carry pulse (borrow pulse) BRP are input to the addition terminal and subtraction terminal of the second counter and are reversibly counted, and output from the first counter 104a. is applied to the subtraction terminal and is reversibly counted. Now, since the capacity iM of the first counter 104a is equal to the number of pulses generated from the direction determining circuit 103 when the hub axle 101 makes one rotation, the first counter 104a
A carry pulse OFF or a carry down pulse BRP is generated depending on the #4 rotation direction every rotation of the second counter 104b.
The total number of revolutions n of the knob shaft from the rewinding position to the current tape running position is stored in the second counter in real time.

During fast forwarding and rewinding, the processing device 107a calculates the remaining tape amount R by calculating the formulas (1) and (2) at regular intervals, and sends the result to the display drive circuit 1 via the switching circuit 108.
06 and displayed on the display unit 105.

Note that the point that the tape running length is calculated by equation (1) will be explained with reference to FIG.

Now, if the tape 202 is wound n times around the take-up hub 201, and if the hub radius is r and the tape thickness is t, then the length of the tape wound on the take-up hub 201 (referred to as tape running length) is It is determined by the following formula. (Solving equation 41 yields L-1yrn(r+-Hn), which matches equation (1).

By the way, the tape running length determined by equation (1) depends on the tape thickness t. The tape thickness t differs depending on each manufacturer, although it is slightly different from the powder type. Therefore, the remaining tape amount R calculated by equations (1) and (2) has an error of about 10 seconds. However, since it is not necessary to display the remaining time with such high accuracy during fast forwarding or rewinding, there is no problem in practical use.

The above is a method for calculating the remaining tape amount R during stop, fast forwarding, and rewinding, but a different calculation method is used during recording or playback. Of course, (1).

The remaining time of the tape during recording and playback may be determined from equation (2), but as described above, some errors occur.

Now, during recording or playback, the processing device 107a
Instead of formula (1), the tape running length is calculated using formula I3). Note that the method for deriving equation (3) is as follows.

If the take-up hub 201 (hub drive shaft 101) takes one rotation time when the tape is wound n times on the take-up hub 201, T (seconds), then the number of times the take-up hub 201 (hub drive shaft 101) moves for ↑ (seconds) is ↑ (seconds). The tape length Lo is calculated by the following formula % (5) or by the following formula % (%) using the playback (recording) speed V (constant).

Therefore, from equations (5) and (6), 2π(r+nt)-v-T (7) is established, so from equations (1) and (7), the length of the tape wound on the winding hub 201 ( tape running length) L is Lmn[-
;-T+πr], and formula (3) is derived. Since the tape running length calculated by this equation (3) does not depend on the tape thickness, it is possible to calculate the remaining tape time with high accuracy from equations (2) and 13).

Now, when the hub axle 101 rotates once, the carry pulse is turned OFF from the first counter 104a according to the rotation direction as described above.
Alternatively, a carry down pulse BRP is generated. These carry pulses and carry down pulses are applied to the second counter 104b) and are also applied to a J- type flip-flop 110 via an OR gate 109, and the J- type flip-flop (referred to as FF) 110 outputs an OR gate output. Set/reset alternately. When the FF 110 is set, the timer 111 measures the time T required for the hub shaft 101 to rotate once from that point until the FF 110 is reset. The timer 111 measures and outputs the time T by counting high-speed clock pulses while the FF 110 is set.

During recording and playback, the processing device 107a records the total number of rotations n of the hub shaft (contents of the second counter 104b), the time T (output of 47-111), and the parameter memory 10.
Using the hub radius r and tape speed vf stored in 7d, calculate the tape running length from the formula number in (3), and then use the maximum recording time Rml stored in general register 107a' to enter parameter memo 1J107d. Maximum tape length L for one side from the stored Rm-Lm table
m is calculated, the remaining tape time R is calculated from equation (2) using L, Lm, and Rm, and the remaining tape time R is calculated from the switching circuit 1.
08 to the display drive circuit 106, and the display unit 10
Displayed on 5.

FIG. 4 is a processing flow diagram of the processing device 1[) 7a.

The total number of rotations of the hub shaft n stored in the reversible counter 104 is stored in the RAM 107c corresponding to the cassette tape set on the deck after play is finished or at a predetermined period.
is stored in the storage area of

By the way, the above is the total hub shaft rotation speed n and the maximum recording time R.
This is a case where m is stored in the storage area of the RAM 107C corresponding to each cassette tape, but n is not necessarily stored.

There is no need to memorize Rm. That is, after Rm is calculated, n may be calculated from equation (7), and the result of the calculation may be set in the reversible counter 104. However, in this method, since n depends on the thickness, a slight error occurs in displaying the remaining amount of tape. Note that from equation (7), the hub shaft rotation speed n can be found as n-(,7,-T-,-)(s). Therefore, by calculating and storing -(=A) and 7(-B) in the parameter memory 107d in advance, the hub shaft rotational speed n can be easily calculated using the following formula (9).

As described above, according to the present invention, the remaining tape time can be displayed by providing only one detection device (rotation detector of the winding hub), which is advantageous in terms of cost. Further, according to the present invention, the remaining tape time can be displayed simply by setting the cassette on the deck and inputting the cassette name without rotating the hub, so the operability is good. Furthermore, according to the present invention, the remaining time on the tape during recording or playback is obtained from an arithmetic expression that does not depend on the thickness of the tape, so that the remaining time can be displayed with high accuracy.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the memory contents of the RAM used in FIG. is a flowchart of processing according to the present invention. 101... Hub drive shaft, 102... Pulse generator,
103...Rotation direction discrimination circuit, 104...Reversible counter, 105...Display section, 108...Switching circuit, 1
11...Timer, 112...Operation panel, 1
12P... Counter button, 112q... Remaining amount display button

Claims (3)

[Claims] (1) In a method for calculating the remaining amount of tape on a cassette tape in a cassette device that records signals on the cassette tape and plays back the recorded signals, each cassette tape is given a name and stored in correspondence with each cassette tape. A storage area is provided, each storage area stores the number of hub revolutions from the rewind position of the cassette tape corresponding to the storage area, and the name of the cassette tape attached to the deck number is input or identified to correspond to the cassette tape. Read the hub rotation speed from the storage area, update the hub rotation speed n based on the hub rotation, calculate the tape length Lt from the hub rotation speed n, the tape thickness t, and the hub outer diameter r, and A method for calculating the remaining tape amount, which is characterized in that the remaining tape amount time R is calculated from the tape length, the maximum recording time Rm on one side, and the maximum tape length Lm on one side using the following formula % formula % (). (2) The tape length is calculated by the following formula % formula %().
) method for calculating remaining tape amount. (3) Let the tape feed speed be V, find the time T required for one revolution of the hub, and convert the above equation (a) into L = n (
The tape remaining amount calculation method according to claim (2), characterized in that L is calculated by transforming it into T-Txr) (C).