JPS6030033B2 - Tape position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape position detection device, such as a linear tape timer of a tape recorder, which detects reel rotation with high precision to determine the current position of the tape.

First, prior to explaining the present invention, a linear tape timer of a tape recorder to which the tape position detecting device of the present invention is applied will be explained with reference to FIG.

In FIG. 1, when the running direction of the magnetic tape 1 is the direction of arrow X, the length (remaining amount of tape) ls of the magnetic tape 1 wound on the supply reel 2, and The length (tape usage or running amount) of the magnetic tape 1 is the same as that of each reel 2.

The time required for the skin to rotate by degrees (n' is a natural number), for example, n
If =1, it can be determined from the rotation periods Ts and Tt. That is, when the outer radius of each reel 2 and 3 (winding radius including the magnetic tape) is dai, rt, the radius of the reel hub is rh, the running speed of the magnetic tape 1 is v, and the thickness of the magnetic tape is 6. ,・S=汀p全一2)
……■ ・t=strokeYtcloud−~2) ……■ becomes.

Here, the ratio P of the tape usage amount lt to the total tape amount ls+lt' is, ,t rt2-rh2
．． ．． ．． ．． ．． ．． ■P in the rain=su・“←However, L=ls ten l
It can be expressed as t.

Here, 2mrs=vt vTS. ．． ．． ．．
．． ．． ■／-rS=;2mrt=VTt・VT
Above......■・-rt=ear; By substituting these ■ and ■ expressions into the above ■ and ■ expressions and adding them, we get L (1S 1t)
= Gei {V2 (TS20M-Koh2}4T2 ..V2 two-party sheep {Baji 2} . . . ■), and substitute this ■ formula and the above ■ formula into the above ■ formula As a result, the following equations are obtained: A = Kotobuki (Gakujyuko h2) B = Vessel rh2.

Here, since A and B are constants, by finding the ratio between the rotation period TS of the supply reel 2 and the rotation period rt of the take-up reel 3, the amount of tape used lt in the total amount of tape L (=ls+lt) can be calculated. The ratio P is calculated. This ratio P
By multiplying by 100, you can display the current tape position as a percentage.Also, if you know the total tape length L and its recording and playback time (one way), you can calculate the above ratio P by multiplying them by , the tape usage amount lt and the tape running time can be displayed as the tape position. In this case, tef. Since the position detection accuracy is determined by the rotation periods Ts and Tt (general analogy: TS/n'Tshi/n), the detection of these rotation periods TS, Tt, etc. It is desirable to improve accuracy. By the way, with cassette tapes, etc., due to uneven tape winding, play in the roll hub, etc., the shape of the outermost periphery of the tape may vary from a perfect circle centered on the central axis of rotation (see the broken line in Figure 2), as shown in Figure 2. It often comes off.

For this reason, the angle to be measured should be as large as possible, for example 3
It is preferable to detect 60 degrees, that is, one rotation, and average out errors caused by uneven winding, backlash, etc. However, as shown in FIG. 3, if measurement is started from the position where the detected part 6 provided on the rotating body 5 of the rotation detector 4 has passed the detection element 7, only one rotation will occur if the rotating body 5 does not make almost one rotation. An eye rotation detection pulse cannot be obtained, and in order to determine the rotation period, it is necessary to perform one more rotation and obtain a second pulse. Therefore, it takes up to two rotations to complete the measurement, and even if the tape position display operation is performed, there is a drawback that it takes a long time until the first display is performed. For example, in an audio cassette tape, it takes approximately 3.4 seconds for one rotation of the reel, so the waiting time until the first rotation detection pulse is obtained is approximately 3.4 seconds at maximum, and the time required until the first display is performed. The maximum value of is about 6
．． It becomes actual sand. In this case, one period is separated to obtain the rotation detection pulse signal, and the period of the divided pulse is determined by the above
If the tape position is detected by substituting it into the formula, the recording time will be shortened, but the detection accuracy will deteriorate because the errors caused by uneven winding and roughness as mentioned above will vary depending on the rotation angle. Undesirable.

Note that if the cassette half, etc., such as a video cassette tape, is finished with high precision and there is little error due to uneven winding, etc., the rotation detection signal may be obtained by dividing 360 degrees into n. However, in order to obtain the desired accuracy, n cannot be made very large, and the device must be rotated by a small angle at most twice the angle of the palm and chin until the first display is made.

The present invention has been made in view of the above circumstances, and it is possible to shorten the maximum time required to obtain the first rotation detection pulse without reducing accuracy, and to reduce the initial display time. An object of the present invention is to provide a tape position detection device that can shorten the time required for detection.

In other words, the tape position detecting device according to the present invention is capable of detecting the tail of the tail coder.

In a tape position detection device having a configuration that detects the time required for rotation of the reel (where n is a natural number) and calculates the current position of the tape based on this time, the rotation detector detects the rotation of the reel. The above.

The present invention is characterized in that it is configured to obtain a number of rotation detection pulses (a natural number equal to or greater than 2) for each body that rotates at a certain degree, and further includes a frequency divider that divides the frequency of the rotation detection pulse into three. It is said that

Therefore, the maximum waiting time until the first rotation detection pulse is obtained at the start of rotation detection can be reduced to 3 times compared to the conventional one, and the time until the first display is obtained after the tape position display side etc. is also shortened. <can.

Also, since the time required for detection is the amount of time it takes for the skin to rotate by several degrees, there is no decrease in detection accuracy. As for the specific configuration of the rotation detector, for example, it is sufficient to provide m detected members such as the rudder and the rotary bar of the rotating body attached to the reel drive shaft.

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

In FIG. 4, a cassette tape 10' has a supply reel 12 and a take-up reel 13, and the magnetic tape 11 runs between these reels 12 and 13 in the direction of arrow X.

Rotation detectors 16 and 17 are arranged on reel drive shafts 14 and 15 that rotate the reels 12 and 13, respectively. The rotation detector 16 includes a rotating body 18 that is attached to the reel drive shaft 14 and rotates in motion with the reel 12;
It also has a detection element 20 fixedly arranged near the rotating body 18. M detected members 19 (where m is a natural number of 2 or more) are provided along the outer periphery of the rotating body 18 at equal intervals. The detection element 20 detects these members 19 to be detected magnetically, photoelectrically, or by other methods. For example, to give an example of detection using a magnetic method, first, a small piece of permanent magnet is used as the member to be detected 19, or the rotating body 18 is made of a magnetic material and is attached at equal intervals, and then the magnetized portion is It may be used as a detection member. Further, as the detection element 20, a general magnetically sensitive element such as a saturable inductance, a magnetic head, a magnetoresistive element, a Hall element, a ferromagnetic metal resistance element, etc. can be used. The rotation detection pulse obtained in this manner is rotated three times by a division period of 211 times. As this frequency divider 21, for example, an m-adic counter that is reset by the first rotation detection pulse may be used, and the period of the pulse obtained by frequency division is equal to the rotation period T of the reel 12. For example, when m=8, the pulses obtained from the arc/rotation detection path A and side and the pulse generator 21 are as shown in FIG. 5B.

Next, the output pulse from this frequency divider 21 is sent to a counter 22.
The first period T is determined as a digital value.

That is, a reference pulse (see FIG. 5D) is sent to this counter 22 from a calculation circuit 23 constructed using a microprocessor or the like. The period t of this reference pulse D is set to be sufficiently shorter than the period T of the pulse B obtained by frequency-dividing the rotation detection pulse A. The counter 22 counts the number of reference pulses included in the period T, which is equal to the period T of the pulse B.
The opening and closing of the reference pulse input gate of the counter 22 is controlled in accordance with the count control pulse C that has a pulse duration of All you have to do is count the number of . Here, the rotation detector 17 on the winding reel 13 side,
The frequency divider 24 and the counter 26 have the same configuration as the rotation detector 16, the frequency divider 21, and the counter 22 on the supply reel 12 side described above, and therefore the description thereof will be omitted. The count value of the reference pulse D obtained in this way is sent to the calculation circuit 23, and the calculation circuit 23 executes the calculation of the above equation (2).

Here, since the above count value is directly proportional to the rotation period T, ■
The above count values may be substituted as they are for TS and Tt in the equation. Through this calculation, the tape position, that is, the ratio P of the tape usage amount lt to the total tape amount L is determined, and this ratio P is displayed on the display device 26. This can be displayed by multiplying P by 100 and displaying it as a percentage, or by subtracting the time required to record and play the entire tape L (one way) to this P, and then calculate the tape running time. may be displayed. As is clear from the above explanation, when the operation button for displaying the tape position is operated, or when the tape recorder starts the tape running operation when the tape position display mode is already activated, the detected member 1 of the rotation detector 16
9 and the detection element 20 (however, the distance along the rotational direction Y of the rotating body 18) is the length between each detected member 19, so the first rotation detection pulse from the start of the tape running operation is Until the ship is shipped, there are a lot of European publications.

This is the time required to rotate one degree.

In other words, the maximum distance can be reduced to three. This is m=8
If we compare the case with the conventional example, the maximum waiting time in the conventional example is about 3.4 seconds, while in this embodiment it is about 0.
The total time will be 429 seconds, which is a reduction of about 3 seconds. In addition,
The conventional example takes approximately 6.5 seconds to complete cycle detection. The parent sand in this example is approximately 3.825 sand. Furthermore, since the frequency divider 21 eliminates shadow skin, one period of tissue is output, so that detection accuracy does not deteriorate.

Desk, - to the history of the boat. The angle of the angle is also the same when detecting the maximum weave, as opposed to the traditional angle.

The time it takes to rotate one degree can be reduced by three degrees, making it difficult to detect problems. The detection accuracy does not deteriorate because the detection is carried out once in a while. Note that the present invention is not limited to the above-mentioned embodiments; for example, in the embodiments, the rotation detector 1
6 shows the use of one detection element 20, but two or more detection elements may be used.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram for explaining the principle of a linear tape timer, Figure 2 is a vague diagram showing the actual state of the tape, Figure 3 is a schematic diagram of a conventional rotation detector, and Figure 4 is a schematic diagram of a conventional rotation detector. A schematic configuration diagram showing an embodiment of the invention, and FIG. 5 is a time chart for explaining the operation of FIG. 4. 10...Cassette tape, 11...Magnetic tape, 12...Supply reel, 13...
Winding roll, 16, 17...Rotation detector, 18
... Rotating body, 19 ... Member to be detected, 2
0...detection element, 21,24...frequency divider, 22,25...counter, 23...
・Calculation circuit, 26...Display device. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. In a tape position detection device having a configuration that detects the time required for a tape reel of a tape recorder to rotate 360/n degrees (where n is a natural number) and calculates the current position of the tape based on this time, the reel a rotation detector that obtains m rotation detection pulses (where m is a natural number of 2 or more) every time the rotation pulse rotates by 360/n degrees, a frequency divider that divides the rotation pulse by 1/m, and a reference pulse. oscillation means for outputting, a counter for counting the number of the reference pulses corresponding between the output pulses from the frequency divider, and a calculation circuit for calculating and outputting the position of the tape based on the output from the counter. A tape position detection device characterized by comprising: