JPS6319955B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a tape position display device that displays the tape position of a tape recorder, and more particularly to a tape position display device that measures and displays the tape running position based on the rotation of a tape reel. In such a tape position display device, there is an error in the measured reel rotation period due to uneven winding of the tape on the reel, detection error during rotation detection, etc. It fluctuates with. For this reason, even if tape running position data is obtained based on measured data of the reel rotation period and this data is displayed, the display will fluctuate due to fluctuations in the above-mentioned error, which visually appears as flickering, which is not desirable. do not have. It is also conceivable to average the data such as the reel rotation period and tape position using an arithmetic processing circuit such as a microprocessor, but this would complicate the circuit configuration and become expensive. The present invention has been made in view of these conventional circumstances, and aims to provide a tape position display device that can prevent the above-mentioned flickering of the display using a simple circuit and can be supplied at low cost. Preferred embodiments of the tape position display device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block circuit diagram showing a first embodiment of the present invention, in which a magnetic tape 4 is wound around supply and take-up reels 2 and 3 of a cassette tape 1. As shown in FIG.
In order to detect the rotation of these supply and take-up reels 2 and 3, the rotation shafts 5 and 3 of these reels 2 and 3 are connected to each other.
6 is detected by rotation detection devices 7 and 8. Here, the rotation detection device 7 (the same applies to 8) has various configurations, but for example, k magnetized portions are formed at equal intervals around a rotating disk 9 attached to the reel rotation shaft 5. A detection element 10 such as a magneto-electric conversion element is fixedly arranged opposite to the rotation detection element 10, and k rotation detection pulses are obtained from the detection element 10 in response to one revolution of the supply reel 2. In addition, various other rotation detection devices 7 are known, such as those that perform photoelectric rotation detection or mechanical rotation detection. Next, the rotation detection pulses obtained from each rotation period detection device 7, 8 are sent to a period detection circuit 11 for measuring the rotation period of each reel 2, 3, and the ratio of these rotation periods is determined, for example. The value is sent to the decoder circuit 12 as digital data. The decoder circuit 12 converts tape position data corresponding to the length l _s (remaining amount of tape) of the tape 4 wound on the supply reel 2 into, for example, 4-bit data based on the ratio of the rotation periods of the respective reels. Output as a digital signal. A first timing pulse TP1, which will be described later, is supplied to this decoder circuit 12, and when this timing pulse TP1 is input, the data of the rotation period ratio at that time is decoded and becomes the tape position data. This data is held until the next timing pulse TP1 is input. This digital signal of tape position data is sent to a comparator circuit 13 and a register circuit 14 for temporary storage. The register circuit 14 latches the tape position data in response to a latch pulse supplied to a latch signal input terminal 15. The tape position data signal latched in the register circuit 14 is sent to the comparison circuit 13 and display drive circuit 16. The display drive circuit 16 drives the display device 17 to turn on in response to, for example, 4-bit position data from the register circuit 14. In this embodiment, for example, 16
A bar graph display device 17 having display segments 18 arranged in a line is used, and if the 4-bit tape position data is converted into a binary value, it is possible to display the tape position in 16 steps. In addition, a 7-segment display element may be used to display numbers, and the number to be displayed is often the remaining time when the tape is running at a constant speed, a percentage value of the remaining amount of the tape, etc. Next, the comparison circuit 13 compares the tape position data from the decoder circuit 12 and the tape position data from the register circuit 14, and outputs an "H" signal as a difference signal when these data do not match. For example, four two-input exclusive OR circuits (exclusive OR circuits, hereinafter referred to as Ex.OR circuits), which correspond to the number of bits of data.
21a, 21b, 21c, 21d, and one four-input OR circuit (OR circuit) 22.
Here, four Ex.OR circuits 21a, 21b, 2
1c and 21d are the 4-bit data from the decoder circuit 12 and the exclusive OR of the corresponding bit digit data with the 4-bit data from the register circuit 14.
Outputs from Ex.OR circuits 21a, 21b, 21c, and 21d are sent to a 4-input OR circuit 22. The output from this OR circuit 22 is the AND gate 23
The signal is sent to the set terminal of the flip-flop circuit 24 via the flip-flop circuit 24. This flip-flop circuit 24
The Q output of is sent to the latch signal input terminal 15 of the register circuit 14 through the AND gate 25. The other input terminal of the AND gate 25 receives a second timing pulse TP2, the reset terminal of the flip-flop circuit 24 receives a third timing pulse TP3, and the AND gate 23 receives a second timing pulse TP2.
The other input terminal of the fourth timing pulse
TP4 is supplied respectively. Next, the operation of the tape position display device having such a configuration will be explained. First, the period detection circuit 11 detects a ratio p between the rotation period Ts of the supply reel 2 and the rotation period Tt of the take-up reel 3.
It outputs digital data according to =Ts/Tt, and this ratio p can be easily determined as follows. That is, the number of magnetized parts formed on each of the rotating disks 9, 9 of the rotation detecting devices 7, 8 is equal to each other.
Then, k pulses are obtained for each rotation of each reel 2, 3. The rotation detection pulses from these rotation detection devices 7 and 8 are shown in FIGS. 2A and 2B, and if the pulse in FIG.
is equal to FIG. 2C shows a frequency-divided pulse when k=4, which is a pulse with a pulse width Ts and a repetition period of 2Ts. This frequency division pulse C gates the rotation detection pulse of the other reel in Figure 2B, and only during the period when the frequency division pulse C is H is shown in Figure 2B.
If the number of pulses is taken out and the number of pulses is counted, the value m/k obtained by dividing the count value m at this time by 1/k becomes equal to the above ratio p (=Ts/Tt). Here, the count value m of the rotation detection pulse B is measured once during the repetition period of 2Ts of the gate pulse C, and the tape position data described below is also obtained once during this measurement period of 2Ts. It will be done. Incidentally, since the count value m is directly proportional to the ratio p, this count value m is used as it is in the period detection circuit 1.
1 may be sent to the decoder circuit 12 as a digital output. Furthermore, by changing the frequency division ratio of the pulse shown in FIG. 2A, the repetition period of the gate pulse shown in FIG. 2C can be changed, and the measurement period can be changed. Next, in the decoder circuit 12, based on the rotation period ratio p of each reel, for example, the length l _s (remaining amount of tape) of the tape 4 wound on the supply reel 2 in FIG. Outputs tape position data according to the tape length _lt (tape usage) wound on the tape. In FIG. 3, the outer radius of the supply reel 2 including the tape is Rs, and the outer radius of the take-up reel 3 including the tape is Rt. At this time, if the running speed of the tape 4 is v, then Ts=2πRs/v ∴Rs=vTs/2π...Tt=2πRt/v ∴Rt=vTt/2π... Also, the diameter of the reel hub of each reel 2, 3 is equal to r, and the thickness of the tape 4 is d.
Then, the length of the remaining tape amount l _s and the length of the tape usage amount l _t are as follows: l _s = π/d(Rs ² − r ² )... _lt = π/d(Rt ² − r ² ) ……. These, Rs and Rt in the formula above,
Substituting each expression, l _s = π/d {(vTs/2π) ² −r ² } ... l _t = π/d {(vTt/2π) ² −r ² } ... Here, the total length of the above tape Since L is l _s + l _t ,
, by adding the expressions, L=π/d{v ² /4π ² (Ts ² + Tt ² )−2r ² } …… ∴v ² =4π ² /Ts ² +Tt ² (Ld/π+2r ² ) …… , substituting v in this equation into the above equation, l _s = π/d{Ts ² /Ts ² +Tt ² (Ld/π+2r ² )−r ² } =L+2πr ² /d/1+(Tt/Ts) ² − πr ² /d...
is obtained, and by substituting the formula into the above formula, l _t = π/d {Tt ² /Ts ² +Tt ² (Ld/π+2r ² )−r ² } = L+2πr ² /d/1+(Ts/Tt) ² − πr ² /d...
is obtained. Here, L+2πr ² /d=A, and πr ² /
If d = B, these A and B are constants, so according to the rotation period ratio p (=Ts/Tt),
The formula is l _t =A/1+p ² -B... Therefore, input p can be decoded to obtain l _t . Note that the above equation also becomes l _s =A/1+(1/p) ² −B . . . , and l _s can be easily obtained from the input p. In this case, it is not necessary to directly quantify the above l _t and l _s ; for example, the entire tape length L is divided into 16 parts, and the decoder circuit 12 generates tape position data that represents the 16 divided areas with 4-bit digital values. You can output it from . Next, the tape position data decoded by this decoder circuit 12 is transferred to the first tape position data shown in B in FIG.
is output in response to the first timing pulse TP1, and is held until the next first timing pulse TP1 is input. In FIG. 4, A indicates a clock signal for obtaining the output timings of the first, second, third, and fourth timing pulses.
, correspond to the output timings of these first, second, third, and fourth timing pulses. Repetition period of timing pulse TP1 in Figure 4B
Tm is equal to the time required to measure the count value m explained in conjunction with FIG. 2, and Tm=2Ts. Furthermore, the rotation detection pulse in FIG. 2A can be used as the clock signal in FIG.
Eight clock pulses are included in between. Furthermore, Da and Db in FIG. 4B represent the decoder circuit 12.
For example, when the timing pulse TP1 is input at time _t21 ,
Data has been changed from Da to Db. Next, FIG. 4C shows the tape position data from the register circuit 14. Here, register circuit 1
4 latches the tape position data from the decoder circuit 12 when the latch pulse is input from the AND gate 25, so the Q of the flip-flop circuit 24 is
Under the condition that the output is "H", the above-mentioned latch is performed at the output timing of the second timing pulse TP2. Next, FIG. 4D shows the output from the comparison circuit 13, and shows the period during which the data in FIG. 4B and the data in FIG. 4C do not match, that is, from time t ₂₁ to t ₃₂ in FIG. 4. A difference signal that is "H" is output during the period up to this point. This difference signal is sent to the AND gate 23, where it is ANDed with the fourth timing pulse TP4 at the above timing, and sent to the set terminal of the flip-flop circuit 24, so that the signal in FIG. 4D becomes "H". ” Time t ₂₄ at which timing pulse TP4 is output
At this point, the flip-flop circuit 24 is set and the Q output becomes "H" as shown in FIG. 4F. The reset terminal of this flip-flop circuit 24 is supplied with a third timing pulse _TP3 having a timing as shown in FIG.
At the input time _t33 of TP3, the flip-flop circuit 24 is reset and the Q
The output becomes "L". While the Q output of the flip-flop circuit 24 is at "H", the second timing pulse is
When TP2 is sent to the AND gate 25, a latch pulse as shown in FIG. 4G is sent from the AND gate 25 to the register circuit 14. The output time of this latch pulse is _t32 , and the tape position data from the decoder circuit 12 updated by the first timing pulse TP1 at time _t31 is
It is latched into the register circuit 14 at _t32 .
Here, in FIG. 4, data from the decoder circuit 12 after time t ₃₁ (but up to time t ₄₁ ) is designated as Db (see FIG. 4B), and this Db is latched at time t ₃₂ . , the data from the register circuit 14 after time _t32 becomes Db. That is, for the above measurement period Tm, the decoder circuit 1
The data from the decoder circuit 12 is latched as is in the register circuit 13 at the timing of the cycle in which a difference between the output data of the decoder circuit 2 and the register circuit 14 is detected. Here, the above data Da, Db, etc. are 4-bit data indicating one area obtained by dividing the total length L of the tape into 16, and the tape position shifts from one area to the next as the tape runs. At this time, the data from the decoder circuit 12 fluctuates due to uneven winding of the tape on the reel, errors in counting, and the like. Table 1 shows an example of data fluctuation when the tape position moves from the data Da area to the data Db area.

【table】

Claims (1)

[Claims] 1. A rotation detecting means for detecting the rotation of a reel around which a tape is wound, a tape position measuring means for measuring the running position of the tape based on the output from the rotation detecting means and outputting tape position data, and a tape position measuring means for outputting tape position data. A register circuit to which output data from the measuring means is sent and stores the output data when a latch pulse is input; a display device that displays the tape position according to the output data from the register circuit; and an output from the tape position measuring means. A comparison circuit that compares the data with the output data from the register circuit and outputs a difference signal when these data are different from each other, and a storage means that holds the difference signal from the comparison circuit until the next tape position measurement. and latch pulse output means for sending a latch pulse to the register circuit only when measuring the next tape position in which the difference signal is stored in the storage means.