JPS61120388A - Detecting device for traveling quantity of tape - Google Patents

Abstract

PURPOSE:To obtain an accurate detection signal for the quantity of tape traveling which shifts in phase gradually by obtaining the detection signal for the quantity of tape traveling on the basis of a signal showing the difference between the count contents of a counter and the hold contents of a holding circuit. CONSTITUTION:This device is equipped with the 1st pulse generating means 30 which detects the traveling of a tape mechanically and generates the 1st pulse, the 2nd pulse generating means 31 which reproduces a position signal recorded on a tape TP and generates the 2nd pulse, a counter 4 which counts the 1st pulse, holding circuits 9 and 15 which hold correction data on the basis of the 2nd pulse, a subtracter 10 which calculates the difference between the count contents of the counter 4 and the hold contents of the holding circuit 9, and discrimination circuits 11 and 16 which generates discrimination signals according to the value of the difference signal and supply them to the holding circuits 9 and 15. Consequently, the detection signal for the quantity of tape traveling is obtained on the basis of the signal of the difference from the subtracter 10. Therefore, even if the 1st and the 2nd pulsed have a large phase difference, the detecting device generates finally the detection signal for the quantity of tape traveling which shifts in phase gradually.

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 (2) has the advantage of continuously obtaining highly reliable tape travel amount detection pulses, but on the other hand, if there is slippage between the tape and the roller, or if the tape expands or contracts, the tape travel There is a drawback that the detection accuracy of the amount detection pulse is reduced.

The device (■) improves on the drawbacks of the device (■), but if there is a dropout in the reproduction of the position signal, it becomes a problem.

The detection accuracy of the travel distance detection pulse also decreases.

Therefore, a tape running N 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, an octal 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 [1] and (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 .degree. is supplied to a 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°zl, zO digit output Q2 Qt Qo from the counter (4), generates one pulse for each cycle of the counter (4), and displays the count display ( 6), and also supplies a gate signal for noise removal to the reset/preset pulse generation circuit (7). The display (6) also receives the tape running direction detection signal from the input terminal (2).This display (6)
The tape running distance is 1 minute 9 seconds, frame (1/30
seconds) format.

The reset/brisent 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) caused by the tape running, and supplies a reset and recent 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 240) Lz 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. 7 will be explained with reference to FIG. 8 as well.

First, consider ignoring the second bus 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. 8A when the binary number is converted into a decimal number. 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 as shown in FIG. 8F when the binary number is converted into a decimal number. 5.4
．． 3.2゜1, 0. 7. 6. It changes like...

A pulse is supplied from the logic circuit (5) to the display (6) when the count content of the counter (4) changes from the maximum to the minimum or from the minimum to the maximum, that is, the most significant digit output Q2 of the counter (4). The value of “1” = “0” or “0” - “1”
” occurs when the change occurs.

The gate signal (which gates the second pulse) supplied from the logic circuit (5) to the reset/brisent 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 8, when the count is 7, as shown in Figure 8C. When the second pulse is generated as shown in FIG. 8, 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 8. From then on, the count content is 1.2. 3. ..., and when the count reaches O, a second pulse is generated as shown in Figure 8C, but the count remains unchanged.
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 precent pulse is supplied from the circuit (7) to the counter (4), and the count content is changed to 7 as shown in Figure 8G. changes to 6.5.4°... and when the count reaches 7, a second pulse is generated as shown in Figure 8C, but the count remains unchanged. As shown in H, when the count content of the counter (4) changes from 2 to 7 and from O to 7, a pulse is obtained from the logic circuit (5) and supplied to the count display (6), The display is each decremented by one.

[Problem that the invention seeks to solve]

By the way, in the tape running amount detecting device shown in FIG. 7, 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, in such conventional devices, the first pulse obtained by mechanically detecting the running of the tape is different from the second pulse obtained by reproducing the position signal recorded on the tape. The drawback is that it is impossible to know whether you are behind or ahead, and what the difference is.

Furthermore, when the phase difference between the first and second pulses is large, there is a drawback that the phase of the finally obtained tape travel amount detection pulse is drastically changed all at once by the second pulse.

In view of these points, the present invention makes it possible to detect the amount of tape travel with high precision, and to detect the distance of the tape by reproducing the position signal recorded on the tape of the first pulse obtained by mechanically detecting the travel of the tape. It is possible to know the phase difference with respect to the obtained second pulse, and further,
The present invention attempts to propose a tape running amount detection device in which the phase of the finally obtained tape running amount detection signal gradually changes even if the phase difference between the first and second pulses is large.

[Means for solving problems]

The tape running amount detecting device according to the present invention includes a first pulse generating means (30) that mechanically detects the running of the tape and generates a first pulse, and a first pulse generating means (30) that reproduces a position signal recorded on the tape TP. A second pulse generating means (31) that generates a second pulse, and a counter (4) that counts the first pulse.
, a holding circuit (9), (15) that holds the correction data based on the second pulse, and a subtracter that calculates the difference between the counted content of the counter (4) and the held content of the holding circuit (9). , a discriminating surface iis (1
1) and (16), and is characterized in that the tape running amount detection signal is obtained based on the difference signal from the subtracter 11.

[Effect]

According to the present invention, based on the output of subtraction 5aω,
An accurate tape running amount detection signal whose phase is gradually changed can be obtained, and a tape running amount detection signal based only on the first pulse can be obtained based on the output of the counter (4).

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. For example, (4) is an octal amplifier down counter, and the first pulse from the mechanical detection of tape running from the input terminal (1) is input to its clock input terminal, and the amplifier/down switching signal input terminal is input to its clock 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 (1), +2) are obtained from the first pulse generating means (30) 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. 6 A, B) with a phase difference of 90° obtained from this to the rotation detection circuit (25).
), the first pulse (240 Hz) (FIG. 6C) and tape running direction detection signal (FIG. 6D) corresponding to the front and rear edges of the rotation pulses in FIGS. 6A and B are obtained.

(9) is a latch circuit, and the 22°2 from the adder (12)
1.20 digit output 12 It Io input D2D
s Do and launches with the second pulse from input terminal (3). As shown in FIG. 5, a position signal (CTL signal) recorded on the side edge of the tape TP in its longitudinal direction
This second pulse (30k) is obtained by reproducing (28) (corresponding to the start position of the odd field of the PJ diagonal trunk) by the second pulse generating means (fixed magnetic head) (31).

α[ is a subtracter consisting of a full adder, and a counter (4
) 22, 21.2G digit output Di (C2QtQ
o) and the 22.21.20 digit output DC (L2 Lx Lo ) of the latch circuit (9) to subtract the latter from the former.

(11) is a discriminator circuit, and from the subtracter Ql (7) 22.2
'.

20 output Do (C2, Cs, Co) and a tape running direction detection signal from an input terminal (2). When the tape TP is running in the forward direction, the subtractor α
If the output Do of l is one of 1.2.3,
+3-+1 is obtained as the output Du, and the output Do is 4.5
, 6.7, when the phase is slow, the output Du is closed -a-
-1 is obtained, and when the output DO is 0 and there is no lead or lag, O is obtained as the output Du. Further, when the tape TP is running in the opposite direction, the output Do of the subtractor α1 is 1.2.
3, if the phase is advanced, the output Do is +am+
l is obtained, and when the output Do is a lagging phase of either 4.5.6, -2m -1 is obtained as the output Du, and the output Do
When is 0 or 7 and there is no lead or lag, 0 is obtained as the output Du.

Note that a may be 2 or more, and may also be made different depending on the value of the output Do.

(12) is an adder which receives the output Da of the launch circuit (9) and the output Du of the discrimination circuit (11) and outputs an addition output DN.
(12It Io), and this output DN is supplied to the latch circuit (9) and latched by the second pulse from the input terminal (3).

In addition, the subtracter 01, the discrimination circuit (11) and the adder (12)
The whole can be configured by ROM.

(5) is a logic circuit, 22°21 from the subtractor aω
．． Upon receiving the 2° digit output Do (C2Ct Co ) and the tape running direction detection signal from the input terminal (2),
A count display (6) generates a rectangular wave signal having a phase difference of 90' for each cycle of the counter (4).
supply to. This display (6) displays the amount of tape travel in the format of time 1 minute 9 seconds and frame (1/30 second).

Furthermore, (13) is another logic circuit, which is a counter (4).
Directly receiving the output Di (C2Qz Qo) of the counter (4), one 90"
A rectangular wave signal having a phase difference of
) to supply the secondary tape running amount for 1 minute.

Displayed in seconds and frames.

Next, the operation of the tape running amount detecting device shown in FIG. 1 will be explained with reference to the time charts shown in FIGS. 2 and 3.

FIG. 2 shows a time chart when the tape TP is running in the forward direction, of which FIG.
Figure 2 H to N show the case in which the output Do is ahead of the second pulse (this is designated as 22) and the case in which it is behind, respectively. (6
), which are rectangular waves with a duty of 50% in steady state, rising when the signal Do is 3-4 and falling when the signal DO is 7-0.

The other tape running amount detection signal (this is designated as Y) is not shown, but when the tape TP runs in the forward direction, it becomes a signal obtained by advancing the signal X by 90 degrees.

As shown in FIG. 2C and F, when the second pulse P2 is generated when Do=3, the latch circuit (9) causes DH-0.
is latched and an output Dc=0 is obtained, and the subtracter Ql subtracts Dc=O from Di-2, so the output D
o immediately decreases by 1 from 3 to 2.

Next, as shown in FIG. 2 C and F, when Do=2, the second
When the pulse P2 of D is generated, the launch circuit (9)
N-1 is latched to obtain an output Dc-1, and since Dc-1 is subtracted from Di-2 in the subtracter 01, the output Do immediately decreases by 1 from 2 to 1.

Next, as shown in FIG. 2C and F, when Do=1, the second
When the pulse P2 of D is generated, the launch circuit (9)
Since N-2 is latched and output Dc=2 is obtained, and Dc=2 is subtracted from Di-2 on the subtracter side, the output Do immediately decreases by 1 from l to 0 and becomes the second pulse. The phase matches Pa. It goes without saying that even if the second pulse P2 is subsequently generated when Do=O, the output Do=O does not change.

Furthermore, as shown in FIG. 2 J and M, when the second pulse P2 is generated when Do=5, the latch circuit (9)
i-4 is latched to obtain the output Dc-4, and the subtracter (
Since Da-4 is subtracted from Dl-2 in II, the output Do immediately increases by 1 from 5 to 6.

Next, as shown in Figure 2 J and M, the second
When the pulse P2 of D is generated, the launch circuit (9)
H-3 is latched and an output Dc-3 is obtained, and since Dc-3 is subtracted from Di =2 in the subtractor (IllI), the output Do immediately increases by 1 from 6 to 7.

Next, as shown in FIG. 2 J and M, when Do=7, the second
When the pulse P2 of D is generated, the launch circuit (9)
N-"2 is latched and the output Dc=2 is obtained, and 0 cm2 is subtracted from Di=2 in the subtracter α, so the output Do immediately increases by 1 from 7 to 0 and the second pulse The phase matches that of P2.

FIG. 3 shows a time chart when the tape TP is running in the opposite direction.
Figure 3 H-N shows the case where the output Do is leading with respect to the second pulse P2, and the case where it is behind the second pulse P2.X is supplied from the logic circuit (5) to the count display (6) A pair of tape running amount detection signals are shown, which are rectangular waves with a duty of 50% during steady state, rising when the output Do is 0-7, and falling when the output DO is 4-3. Ikekata's tape running amount detection signal Y is not shown, but when the tape TP runs in the opposite direction, it becomes a signal that is delayed by 90 degrees from the signal X.

As shown in FIG. 3C and F, when the second pulse P2 is generated at DO-4, the latch circuit (9) causes DN="
0 is latched and the output Dc=O is obtained, and Dc=0 is subtracted from Di=5 in the subtracter a (to), so
The output Do immediately increases by 1 from 4 to 5.

Next, as shown in FIG. 3C and F, when Do=5, the second
When the pulse P2 of D is generated, the latch circuit (9)
N-7 is latched to obtain an output Dc-7, and since Dc-7 is subtracted from Di =5 in the subtracter θ, the output Do immediately increases by 1 from 5 to 6. .

Next, as shown in FIG. 3C and F, when Do=6, the second
When the pulse P2 of D is generated, the latch circuit (9)
N=6 is latched to obtain the output Dc=6, and the subtracter O
Since Dc=6 is subtracted from Di-5 in 1,
The output Do immediately increases by 1 from 6 to 7 and matches the phase of the second pulse Pa.

Moreover, as shown in FIG. 3 J and M, when the second pulse P2 is generated when Do=2, the launch circuit (9)
"4 is latched to obtain the output Dc-4, and the subtracter al
Since Dc-4 is subtracted from Di=5 at lI, the output Do immediately decreases by 1 from 2 to 1.

Next, as shown in FIG. 3 J and M,
When the pulse P2 of D is generated, the launch circuit (9)
N=5 is launched to obtain the output Dc-5, and the subtractor α
Since Dcm5 is subtracted from Di=5 at ω, the output Do immediately decreases by 1 from 1 to 0 and is in phase with the second pulse Po.

In this way, the output Do of the subtracter 0α and the second pulse P2
Even if the phase difference is large, the phase difference is gradually reduced each time the second pulse P2 arrives.
Even if a tape running amount detection signal having a phase difference of 2 is obtained and this signal is supplied to the count display (6), there is no possibility of malfunction in the count display. Incidentally, 2 with a phase difference of 90° including direction information
This type of count/display device (6) that receives two rectangular wave signals and displays the count may malfunction if the phase of the tape travel amount detection signal changes significantly.

Furthermore, even if noise is mixed into the second pulse, the subtracter O1
Since the output does not change significantly, such a device is less susceptible to malfunctions due to noise.

Next, another embodiment of the present invention will be described with reference to FIG. 4, but portions in FIG. 4 that correspond to those in FIG. .

(15) is another counter, and its 2', 2'', 2° digit output DC (P2 PIPo) is supplied to the subtracter 01ll, and the output Di (C2QI Q
(16) is a discriminator circuit that calculates the phase-inverted signal C2CI Co -K (K2 KL
KO) and converts it into a reference signal J (J2 JI JO
)(="100"-4). In addition, K Hani-Do
It becomes +4.

Then, the input terminal (
3) controls an up/down counter (15) that counts the second pulses from 3). That is, when J<K, the downter is caused to stop counting, and when J-, the counting is stopped.

Next, the operation of the tape running amount detecting device shown in FIG. 4 will be explained with reference also to the above-mentioned FIGS. 2 and 3.

However, the output of the counter (4) is D11, the output of the counter (15) is Dc, and the output of the subtracter O1 is Do.

First, the operation when the tape TP is running in the forward direction will be explained. As shown in FIGS. 2C and F, when the second pulse P2 occurs when Do=3, the counter (15) goes up because it is K-7, and the output Dc of the counter (15) changes from 7 to 0. Di-2 in the subtractor Ql
Since Dc=0 is subtracted from , the output Do becomes 3 immediately.
decreases by 1 from 2 to 2.

Next, as shown in FIG. 2 C and F, when Do=2, the second
When pulse P2 is generated, the counter (15) becomes an amplifier since it is K-6, and the output Dc
changes from O to 1, and Dc-1 is subtracted from Di=2 in the subtractor α, so the output Do immediately decreases by 1 from 2 to 1.

Next, as shown in FIG. 2C and F, when Do=1, the second
When pulse P2 is generated, since K=5, the counter (15) becomes an amplifier, and the output D of the counter (15)
c changes from 1 to 2, and in the subtractor αω, Di = 2
Since Dc=2 is subtracted from , the output DO becomes 1 immediately.
It decreases by 1 from 0 to 0, and the phase matches that of the second pulse P2. Note that even if the second pulse P2 is subsequently generated when Do=O, the output Dc of the counter (15) does not change at K-4, so the output Do=0 also does not change.

Also, as shown in FIG. 2 J and M, when the second pulse P2 is generated at Do-5, since K=1, the counter (
15) goes down, the output Dc of the counter (15) changes from 5 to 4, and Dc=4 is subtracted from Di=2 in the reducer aO1, so the output Do immediately changes from 5 to 6 by 1. increase

Next, as shown in FIG. 2 J and M, when Do=6, the second
When pulse P2 is generated, the counter (15) goes down because it is K-2, and the output Dc of the counter (15)
changes from 4 to 3, and Dc-3 is subtracted from Di =2 in the subtractor α, so the output Do immediately increases by 1 from 6 to 7.

Next, as shown in Fig. 2 J and M, the second
When path P2 occurs, the counter (
15) goes down, the output Dc of the counter (15) changes from 3 to 2, and in the subtraction BQ[l, Dc-2 is subtracted from Di = 2, so the output Do immediately changes from 7 to 0 by 1. The pulse increases and the phase matches that of the second pulse P2. .

Next, the operation when the tapes T and P are running in opposite directions will be explained. D, as shown in Figures 3C and F.

-4, when the second pulse P2 is generated, the counter (15) goes down because it is K-0;
) changes from 1 to O, and the subtracter α1 subtracts Dc-0 from Di-5, so the output Do immediately increases by 1 from 4 to 5.

Next, as shown in FIG. 3C and F, when Do=5, the second
When pulse P2 is generated, since K=1, the counter (
15) goes down, the output Dc of the counter (15) changes from 0 to 7, and the subtracter On subtracts Dc = 7 from Di = 5, so the output Do immediately increases by 1 from 5 to 6. do.

Next, as shown in FIG. 3C and F, when Do=6, the second
When pulse P2 is generated, the counter (15) goes down because it is K-2, and the output Dc of the counter (115)
changes from 7 to 6, and Dc-6 is subtracted from Di = 5 in the subtracter Ql, so the output Do immediately increases by 1 from 6 to 7 and is in phase with the second pulse P2.

Also, as shown in FIG. 3 J and M, when the second pulse P2 is generated when Do=2, the counter (
15) goes up, the output Dc of the counter (15) changes from 3 to 4, and the subtracter Ql subtracts Dcx4 from Di=5, so the output Do immediately decreases by 1 from 2 to 1.

Next, as shown in FIG. 3 J and M, when DO=1, the second
When pulse P2 is generated, the counter (15) goes up because K=5, and the output Dc of the counter (15)
changes from 4 to 5, and Dc=6 is subtracted from Di=5 in the subtracter On, so the output Do immediately decreases by 1 from 1 to O, and matches the phase of the second pulse P2.

In addition, in FIG. 4, the counter (15) is assumed to be a 24-decimal counter, and the output Pt of the 23rd, 22nd, 21st, and 20th digits is
P2 PI Output of the upper 3 digits of PG P3Pzl't
(Dc) may be supplied to the subtractor O1, so that even if the second pulse of the counter (15) is supplied, as long as two pulses are not supplied, the output P3
Since P2 PL does not change, the phase change of the output Do of the subtractor α becomes even more gradual. In addition, the counter (
If the base number of 15) is set to 26 or more and the output of the upper three digits is supplied to subtractor 00, the output DO of subtractor 0 will be
The phase change becomes even more gradual.

〔Effect of the invention〕

According to the present invention described above, the amount of tape travel can be detected with high accuracy, and the distance of the first pulse obtained by mechanically detecting the tape travel can be detected by reproducing the position signal recorded on the tape. It is possible to know the phase difference with respect to the obtained East 2 pulse, and furthermore,
Even if the phase difference between the first and second pulses is large, it is possible to obtain a tape running amount detection device in which the phase of the finally obtained tape running amount detection signal gradually changes.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIGS. 2 and 3 are time charts for explaining the same, and FIG. 4 is a block diagram showing another embodiment of the present invention. FIG. 5 is a layout diagram showing some means of the embodiment of the present invention, FIG. 6 is a time chart for explaining the same, and FIG.
The figure is a block diagram showing a conventional device, and FIG. 8 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 launch circuit (holding circuit), αψ is a subtracter, (11) and (16) are discrimination circuits, (15) )
is a counter (holding circuit), (30) is a first pulse generating means, and (31) is a second pulse generating means. Figure 5 t! Fig. 6 [) xi mini-Gyakuman-hyaku- Fig. 8

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 holding circuit that holds correction data based on the second pulse; a subtracter that calculates the difference between the counted contents of the counter and the held contents of the holding circuit; 1. A tape running amount detecting device, comprising: a discrimination circuit for generating a signal and supplying it to the holding circuit, and obtaining a tape running amount detection signal based on a difference signal from the subtracter.