JPS61129787A - Tape travelling quantity detecting device - Google Patents

Abstract

PURPOSE:To detect a tape travelling quantity with a high accuracy and to confirm always tape travelling direction information by discriminating a phase of the counting of the counter for the second pulse, and changing an anti-loga rithm of the counter in accordance with the fact whether a condensive phase or lagging phase. CONSTITUTION:A roller 20 is installed which rotably contacts to a magnetic tape TP and rotates by travelling of the tape, a rotating detecting device 21 is fitted to this, the first and second rotating pulses with a phase difference of 90 deg. obtained are supplied to a rotating detecting circuit 25, the first pulse and a tape travelling direction detecting signal are obtained corresponding to the front and rear edges of the rotating pulse. By reproducing, with the second pulse generating means 31, a position signal 28 recorded in the length- wise direction to the side end of the tape TP, the second pulse is obtained. A control circuit 10 receives outputs Q2, Q1 and Q0 of a counter 3 and outputs L2, L1 and L0 from a latch circuit 9, discriminates a phase of the counting of the coutner 4 for the second pulse and controls in accordance with the fact whether a condensive phase or a lagging phase. Thus, a correct tape travelling quantity detecting signal can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tape running amount detection device suitable for use in VTRs, audio tape recorders, etc.

[Conventional technology]

Conventional tape running amount detection devices include the following. ■ A roller is provided that contacts the magnetic tape and rotates as the tape runs, a rotation detector is attached to the roller, and the tape travel distance detection pulse from this rotation detector drives a count display to determine the tape travel distance. Display. ■Position signals (CT
L signal) is recorded, the tape is run, this position signal is reproduced by a magnetic head, and a tape running amount detection pulse from the magnetic head drives a counter display to display the tape running amount.

The device described in (2) has the advantage of continuously obtaining highly reliable tape running amount detection pulses, but if there is slippage between the tape and the roller or there is expansion or contraction of the tape, the tape running amount cannot be detected. This has the disadvantage that the pulse detection accuracy is reduced.

Although the device (2) improves the drawbacks of the device (2), if there is a dropout in the reproduction of the position signal, the detection accuracy of the tape travel amount detection pulse still decreases.

Therefore, a tape running amount detection device has been proposed in which the accuracy of the tape running amount detection pulse is improved by combining the devices (1) and (2) (see Japanese Patent Publication No. 5B-9504).

The conventional tape running amount detecting device will be described below with reference to FIG. In the embodiment of the above-mentioned publication, a quinary counter is used, but in order to simplify the explanation, a daily digit counter will be used in this example. (4) is an octal up/down counter, and the clock input terminal is connected to the first counter by mechanical detection of tape running from the input terminal (1).
The pulse of is applied to the up/down switching signal input terminal,
A tape running direction detection signal based on mechanical detection of tape running is supplied from an input terminal (2).

The signals supplied to the input terminals (11, (2)) are obtained as follows: A rotation detector is attached to a roller that is in rolling contact with the magnetic tape and rotates as the tape runs; A rotation pulse having a phase difference of . is supplied to the rotation detection circuit, and both of the above-mentioned signals are obtained from the rotation detection circuit.

(5) is a logic circuit which receives the 22° and 21.2° digit output Q2QiQo from the counter (4) and generates one pulse for each cycle of the counter (4) to display the count display ( 6), and also supplies a gate signal for noise removal to the reset/preset pulse generation circuit (7). Incidentally, the display device (6) also receives a tape running direction detection signal from the input terminal (2). This display (6) displays the amount of tape travel in the format of time 1 minute 1 second and frame (1/30 second).

The reset/preset pulse generation circuit (7) receives the tape running direction detection signal from the input terminal (2) and the tape running direction detection signal from the input terminal (2).
3) receives the second pulse (gated by the above-mentioned gate signal) from the tape running, and supplies a reset and preset pulse to the counter (4) based on this.

The second pulse supplied to the input terminal (3) is a position signal (C
This is the reproduction signal of the TL signal) by the magnetic head.

In this case, the second pulse is a 30 Hz pulse when the tape runs at a constant speed. Therefore, the frequency of the first pulse is 240Hz when the tape is running at a constant speed.
(=30Hz x 8).

Next, the operation of the tape running amount detecting device shown in FIG. 5 will be explained with reference to FIG. 6 as well.

First, consider ignoring the second pulse to be supplied to the input terminal (3). In this way, when the tape runs in the positive direction and the counter (4) counts in the positive direction by the first pulse, the content of the count is expressed as shown in FIG. As shown in , ・ ・ , 0.
1, 2, 3, 4.5, 6, 7°0.1, 2, 3.・
It changes like... Also, the tape runs in the opposite direction,
When the counter (4) counts in the reverse direction by the first pulse, the contents of the count are converted from binary to decimal as shown in FIG. 5.4
, 3.2°1.0, 7.6. It changes like...

The pulse supplied from the logic circuit ffl (51) to the display (6) is generated when the count content of the counter (4) changes from the maximum to the minimum or from the minimum to the maximum.
), the value of the most significant digit output Q2 is "1" - "0" or "0"
- Occurs when the signal changes to "l".

The gate signal (which gates the second pulse) supplied from the logic circuit (5) to the reset/preset pulse generation circuit (7) is applied to the counter (
It is a signal that becomes high level when the count content of 4) is 6-2 or 2-6, and becomes low level otherwise.

Next, consider also the second pulse supplied to the input terminal (3). When the tape is running in the forward direction and the counter (4) is counting in the forward direction by the first pulse as shown in Figure 6, when the count is 7, as shown in Figure 6C. When the second pulse is generated as shown, a reset pulse is supplied from the circuit (7) to the counter (4), and the count content is changed to 0 as shown in Figure 6. From then on, the count content is 1.2, 3. ..., and when the count reaches 0, a second pulse is generated as shown in FIG. 6C, but the count remains unchanged. And the sixth
As shown in the figure, when the count content of the counter (4) changes from 7 to O, a pulse is obtained from the logic circuit (5) and supplied to the count display (6), and the display increases by 1. I am forced to do it.

Further, when the tape runs in the opposite direction and the counter (4) is counted in the opposite direction by the first pulse as shown in FIG. When the second pulse is generated as shown in Figure C, a preset pulse is supplied from the circuit (7) to the counter (4), and the count content is changed to 7 as shown in Figure 6G. 6, 5, 4 degrees, etc., and when the count reaches 7, a second pulse is generated as shown in FIG. 6C, but the count does not change. As shown in FIG. 6H, when the count content of the counter (4) changes from 1 to 7 or from 0 to 7, a pulse is obtained from the logic circuit (5) and the count display (6) are supplied, and their displays are each decremented by one.

[Problem that the invention seeks to solve]

By the way, in the tape running amount detecting device shown in FIG. 5, the count content of the counter (4) that counts the first pulse is
Since it is changed by the pulse of , the tape running amount can be detected with high accuracy. However, on the other hand, with such conventional devices, the continuity of the count of the counter is lost, so
There is a drawback that tape running direction information cannot be obtained from data transitions at minute resolutions.

In view of these points, the present invention seeks to propose a tape running amount detection device that can detect the tape running amount with high precision and can always obtain tape running direction information based on data transitions with minute resolution. .

[Means for solving problems]

The tape running amount detection device according to the present invention includes a first pulse generator 12 (30) that mechanically detects the running of the tape and generates a first pulse, and a first pulse generator 12 (30) that reproduces a position signal recorded on the tape. A second pulse generating means (30) that generates a second pulse, a counter (4) that counts the first pulse, and a latch circuit (4) that latches the counted contents of this counter (4) with the second pulse. 9), and determines the phase of the count of the counter (4) with respect to the second pulse based on the count content of the counter (4) and the latch content of the launch circuit (9), and determines whether this phase is leading or lagging. counter (
4) a control circuit αω for changing the base number.

[Effect]

According to the present invention, an accurate tape running amount detection signal can be obtained based on the output of the counter (4) or the control circuit, and the continuity of counting by the counter (4) is not impaired.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. (4) is an amplifier down counter whose base number can be switched to, for example, ternary, quaternary, and quinary, and the first pulse from the input terminal (1), which is generated by mechanical detection of tape running, is input to the clock input terminal of the amplifier down counter. A tape running direction detection signal based on mechanical detection of tape running is supplied from the input terminal (2) to the up/down switching signal input terminal.

The signal supplied to the input terminal (17, (2)) is obtained from the first pulse generating means (3) shown in FIG.

That is, a roller (20) that is in rolling contact with the magnetic tape TP and rotates as the tape runs is provided, and a rotation detector (a rotating magnet (22) attached to the roller (20) via a shaft) is provided.
and magnetic heads (23) and (24))
(21), and supply the first and second rotation pulses (Fig. 4 A, B) with a phase difference of 90° obtained from this to the rotation detection circuit (25).
), the first pulse (120 Hz) (FIG. 4C) and tape running direction detection signal (FIG. 4D) corresponding to the front and rear edges of the rotation pulses of FIGS. 4A and B are obtained.

(9) is a latch circuit, and the 22°2 from counter (4)
t, 2o digit output Q2 Qt Input Qo D2 DI
It is received as Do and latched with the second pulse from the input terminal (3). As shown in FIG. 3, the position signal (CTL signal) recorded in the longitudinal direction on the side edge of the tape TPO (corresponding to the start position of the odd field of the inclined track) (28) is transmitted to the second pulse ordering means (fixed This second pulse (30 Hz) is obtained by reproducing using the magnetic head (31).

Ql is a control circuit, and the output Q2 of the counter (4) QI
Output L2 LI LO from QO and latch circuit (9)
Based on this, the phase of the count of the counter (4) with respect to the second pulse is determined in consideration of the running direction of the tape TP, and depending on whether the phase is leading or lagging, The base numbers of the counters (4), which are normally in 4 bases, are controlled to become 5 bases or 3 bases, respectively, and to hold the base numbers in 4 bases when they are in phase. The control circuit Qtll has an input terminal (2)
A tape running direction detection signal is also supplied. This tape running direction detection signal is corrected in the control circuit αl based on the change in the count of the counter (4), that is, the detection output of whether it is in an increasing direction or a decreasing direction. This is useful when the running direction of the tape TP changes midway.

Data D2 Dt Do (10
Base 0. 1. 2. 3. (binary number corresponding to 4)
to load. Further, this load signal is supplied to a delay circuit (12) to generate a reset signal, which is then supplied to a latch circuit (9).

Further, a tape running amount detection signal and a tape running direction detection signal are obtained from the control circuit Ql (a counter (4) may also be used) and supplied to the count display (6). This display (6) displays the amount of tape travel in the format of time 1 minute 1 second and frame (1/30 second).

Next, referring to FIG. 2, the operation of the apparatus shown in FIG. 1 will be explained. In Figure 2, for convenience of explanation, Figure 2 A-I
The common times Tl, T2, . . .

Set T1-1. FIG. 2A shows the second pulse from the input terminal (3), which is common to FIG. 2 B-T,
Time T3. Tt, which occurs within T11.

First, a case where the tape TP is running in the forward direction will be described. In this case, when the latch content of the latch circuit (9) is 1, the count of the counter (4) is progressing with respect to the second pulse, and the latch content of the latch circuit (9) is 2.3.
(or 2), the counter (4) for the second pulse
When counting is delayed and the latch content of the launch circuit (9) is 0 (or 3), the counter (
It is assumed that it is determined based on the control number fil that the counts in 4) are in phase. Further, when the count of the counter (4) is O, a tape running amount detection signal is obtained from the control circuit a and is supplied to the count display (6) and counted.

When the control circuit αω determines that the count of the counter (4) is ahead of the second bulk signal, the control circuit Ql
changes the base number of the counter (4) from 4 base to 5 base,
After that, it returns to 4 bases again. Further, when the control circuit (II) determines that the count of the counter (4) is delayed with respect to the second pulse, the control circuit aω changes the base number of the counter (4) from quaternary to ternary, and then When the control circuit Ql determines that the count of the counter (4) is in phase with the second pulse, the control circuit side maintains the decimal number for the counter (4) as a quartal number.

First, the operation when the tape TP runs in the forward direction and the counting phase of the counter (4) lags behind the second pulse will be described. As shown in FIG. 2B, the count content of the counter (4) changes from 0° to 1.2 from time T1 to T3. As shown in FIG. 2A, a second pulse is generated at time T3, and the count content 2 of the counter (4) is changed to the latch circuit (
9), and the latched contents 2 are supplied to the control circuit α1. The control circuit 01 determines that the count of the counter (4) is delayed with respect to the second pulse, and the count of the counter (4) is delayed.
) to immediately change the base number from quaternary to ternary (at time T4, load 0 into counter (4)), then return to the original quaternary (at time T8, load 0 into counter (4)) ), therefore, the count contents of the counter (4) are 0. 1. 2. 3, a second pulse occurs at time T7, and the counter (4)
The count content 3 is latched in the latch circuit (9), and the launch content 3 is supplied to the control circuit α0. Control circuit (1
At 01, it is determined that the count of the counter (4) is in phase with the second pulse, and the base number of the counter (4) is held in 4 bases.

Thus, as shown in FIG. 2C, the time T1. when the count of the counter (4) becomes O. T4. At Ts and TL2, a tape running amount detection signal is obtained from the control circuit aω and supplied to the count display (6).

Next, the operation when the tape TP runs in the forward direction and the counting phase of the counter (4) is ahead of the second pulse will be described. As shown in the second diagram, the count content of the counter (4) changes to 3°OlI from time T1 to T3. As shown in FIG. 2A, a second pulse is generated at time T3', the count content I of the counter (4) is latched in the latch circuit (9), and the latch content 1 is supplied to the control circuit aei. be done. In the #I control circuit α, the counter (4
) is judged to be ahead of the second pulse,
At time T7, load O into the counter (4) to immediately change the base number of the counter (4) from quaternary to quinary.)
, and then returns to the original quaternary system (at time T11, 0 is loaded into the counter (4)). Therefore, counter (4)
The counting contents are 2, 3, 4.0 from time T to T7.
Then, at time T7, a second pulse is generated, the count content 0 of the counter (4) is transferred to the latch circuit (9), and the latch content is supplied to the control circuit α. In the control circuit αΦ, it is determined that the count of the counter (4) is in phase with the second pulse, and the base number of the counter (4) is held in 4 bases.

Thus, as shown in FIG. 2C, at times T2, Tt, and TL'l when the count of the counter (4) becomes O, a tape running amount detection signal is obtained from the control circuit Ql.
It is supplied to the counting display (6).

Next, a case where the tape TP is running in the opposite direction will be explained. In this case, when the latched content of the latch circuit (9) is 1, the count of the counter (4) is delayed with respect to the second pulse, and the latched content of the latch circuit (9) is 2.3.
(or 2), the counter (
When the count of 4) is progressing and the latch content of the latch circuit (9) is 0 (or 3), the control circuit αl determines that the count of the counter (4) is in phase with the second pulse. shall be taken as a thing. Also, the count of the counter (4) reaches the maximum value (2
, 3 or 4), a tape running amount detection signal is obtained from the control circuit αl, and is supplied to the counting display (6) for counting.

When the control circuit a1 determines that the count of the counter (4) is ahead of the second pulse, the control circuit Ql
changes the base number of the counter (4) from 4 base to 5 base,
After that, it returns to 4 bases again. In addition, a counter (4
) is delayed with respect to the second pulse, the control circuit Ql changes the decimal number of the counter (4) from 4 to 3.
Change it to decimal, then change it back to quartal. Control circuit (1
When it is determined that the count of the counter (4) is in phase with the second pulse at m, the base number for the counter (4) by the control circuit aφ is held in 4 base.

First, the operation when the tape TP runs in the opposite direction and the counting phase of the counter (4) lags behind the second pulse will be described. As shown in FIG. 2f, the count of the counter (4) changes to 3°2.1 from time T1 to T3. As shown in FIG. 2A, a second pulse is generated at time T3, and the count content 1 of the counter (4) is changed to the latch circuit (
91, and its latch contents l are sent to the control circuit Q[1
1. In the control circuit error, it is determined that the count of the counter (4) is delayed with respect to the second pulse, and the digit number of the counter (4) is immediately changed from quaternary to ternary at time T5.
At time T8, the counter (4) is loaded with 2), and then returned to the original quaternary system (at time T8, the counter (4) is loaded with 3). Therefore, the count content of the counter (4) changes from 0.2 to 1.0 from time T4 to T7,
A second pulse is generated at time T7, and the count content 0 of the counter (4) is latched by the latch circuit (9), and the latched content 0 is supplied to the control circuit a1. *In the control circuit α4, it is determined that the count of the counter (4) is in phase with the second pulse, and the base number of the counter (4) is held in 4 bases.

Thus, as shown in FIG. 2C, at times TL, T5. Tll.

At T12, the tape running amount detection signal is detected by the control circuit 01.
and is supplied to the counting display (6).

Next, the operation when the tape TP runs in the opposite direction and the counting phase of the counter (4) is ahead of the second pulse will be described. As shown in FIG. 2H, the count of the counter (4) changes to 0°3.2 from time T1 to T3. As shown in FIG. 2A, a second pulse is generated at time T3, and the count value 2 of the counter (4) is changed to the latch circuit (2).
9), and the latched contents 2 are supplied to the control circuit 01. In the control circuit αω, it is determined that the count of the counter (4) is advanced with respect to the second pulse, and the counter (
Immediately change the base number of 4) from 4 base to 5 base (at time T6, load 4 into counter (4)), then return to the original 4 base (at time T11, load 4 into counter (4))
3). Therefore, the count content of the counter (4) changes to 1, 0.4.3 from time T4 to T7, and the second pulse is generated at time T7, and the count content of the counter (4) changes to 1, 0.4.3 from time T4 to T7.
The count content 3 is latched in the latch circuit (9), and the launch content 3 is supplied to the control circuit 0. Control circuit αl
In this case, it is determined that the count of the counter (4) is in phase with the second pulse, and the base number of the counter (4) is held in 4 bases.

Thus, as shown in FIG. 2C, at times T2, Ts, and Tt't when the count content of the counter (4) reaches its maximum value, the tape running amount detection signal is obtained from the control circuit 0ω, and the count is displayed. (6).

In addition, in the above, the control circuit is 0ψ and the counter (4)
When the phase of the count with respect to the second pulse is leading or lagging, the base number of the counter (4) is immediately changed, but one cycle of the count of the counter (4) (from 0 to the maximum value or from the maximum value to the maximum value) O) You may change the base number later.

〔Effect of the invention〕

According to the present invention described above, it is possible to obtain a tape running amount detection device that can detect the tape running amount with high precision and can always obtain tape running direction information by data transfer at minute resolution. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a time chart for explaining the same, FIG. 3 is a layout diagram showing some means of an embodiment of the present invention, and FIG. 4 5 is a block diagram showing a conventional device, and FIG. 6 is a time chart for explaining the same. (4) is a counter, (5) is a logic circuit, (6) is a count display, (9) is a latch circuit, aφ is a control circuit, (3
0) is the first pulse generating means, and (31) is the second pulse generating means. Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] a first pulse generating means that mechanically detects the running of the tape and generates a first pulse; and a second pulse generating means that reproduces a position signal recorded on the tape and generates a second pulse. and a counter that counts the first pass,
a latch circuit that latches the count content of the counter with the second pulse; and a latch circuit that determines the phase of the count of the counter with respect to the second pulse based on the count content of the counter and the latch content of the latch circuit; and a control circuit that changes the digit of the counter depending on whether the phase is leading or lagging, and a tape running amount detection signal is obtained from the counter or the control circuit. Tape travel amount detection device.