JPS6168758A - Recording or reproducing device - Google Patents

Abstract

PURPOSE:To stop a tape accurately to a desired position by driving a capstan by a required number of drive pulses in order to stop the tape to the desired position. CONSTITUTION:A reproduced tracking error signal from a terminal 21 is processed by a comparator 26 to which a reference voltage is fed and a differentiation circuit comprising a capacitor C1 and a resistor R5, and an on-track signal is fed to a clock terminal CK of a D FF35. The FF35 is set by a head switching rotary drum phase signal from a terminal 22 via D FF32, 33 and a Q output with a prescribed with is generated as a gate pulse. An AND gate 36 to which a still command signal is fed is opened for a prescribed period by the gate pulse, a drive pulse from the D FF34 is fed to capstan motor for a prescribed number, a tape is stopped accurately at a track start position by on-track and excellent still reproduction is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a recording or reproducing apparatus, and particularly to control of transport of a tape-shaped recording medium when stopping the medium at a desired stop position.

<Description of Prior Art> An example of a device that performs such tape-shaped recording medium stop control is a video tape recorder (VTR) that records and plays back video signals. Tape stop control during playback will be explained.

When playing still images (still playback) on a VTR,
To stop the tape, there is a difference in slope between the video track on the tape and the trace trajectory of the rotating head.

Therefore, points at which the playback signal level drops appear at regular intervals, and these points become noise par on the playback screen.

FIG. 1 is a diagram showing the relationship between the trace locus of a rotary head and recording tracks in a VTR. In Figure 1, L
A, 2A, 3A are recording tracks by the first rotary head, 1'E, 2B, 3B are recording tracks by the second rotary head, 4 is a magnetic tape, and track IA
, 2A, 3A and tracks IB, 2B, 3B have different magnetization directions.

In FIG. 1, LS is an ideal trace trajectory when the first rotary head and the second rotary head alternately trace the magnetic tape 4 to reproduce still images.

IS indicates an ideal trace locus when a still image is reproduced by tracing the magnetic tape 4 alternately with a first rotating head and a head having the same magnetization direction as the head.

FIG. 2 is a diagram showing an envelope waveform of a reproduced video signal during still image reproduction. Figure 2(a) shows a 30Hz rectangular wave signal (30PG) synchronized with the rotation of the rotary head, and the rising and falling edges of 30PG in the figure indicate the timing at which tracing of a track by the rotary head starts or ends. It shows. That is, for example, the first rotary head traces the track during 1/80 seconds when 30PG(a) is at high level (H).

When a still image (frame still) is being played back based on the trace trajectory of LS, the first rotary head is alternately reproducing track LA and the second rotary head is reproducing track 2A, and the reproduction signal is The envelope waveform is as shown in FIG. 2(b). Now, if the trace trajectory of the head during frame still deviates from the ideal trace trajectory shown in LS, the playback envelope waveform will be as shown in Figure 2 (b'), for example, and the signal degradation portion indicated by X in the figure will occur. This appears as horizontal line noise on the playback screen.

On the other hand, when still image playback (field still) is performed using the IS trace trajectory, track 3A is repeatedly played back by the first rotating head and a head with the same magnetization direction, and the playback signal is The envelope waveform is as shown in FIG. 2(C). On the other hand, if the trace trajectories of these heads deviate significantly from the ideal track trajectories shown in Is, the envelope waveform becomes, for example, as shown in FIG. It appears as band-like noise.

In order to match the trace locus of the head with the ideal trace locus as described above, it is necessary to accurately determine the tape stop position. In conventional VTRs, for example, the tape is driven at low speed, a control signal (CTL) recorded in the longitudinal direction at the end of the tape is reproduced, and the brake is applied in accordance with a timing signal obtained using this control signal. The tape was stopped.

However, in this case, due to variations in the characteristics of the brake, capstan motor, etc., the desired stopping position 5, for example, IS
It was difficult to accurately stop the vehicle at the ideal stopping position as shown in , LS.

<Object of the Invention> The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to provide a recording or reproducing device that can extremely accurately stop a tape-shaped recording medium at a desired stopping position. shall be.

<Explanation based on examples> An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a diagram showing a schematic configuration of a VTR as an embodiment of the present invention. In Figure 3, 4 is a magnetic tape,
It is wound around the rotating drum 6 over an angular range of 180° or more. Heads 5a and 5b having different magnetization directions with a phase difference of about 1806 are attached to the drum 6. Further, a head 5c having the same magnetization direction as the head 5a is attached adjacent to the head 5b. The signals picked up from these heads are sent to the head switching circuit (
It is made into a continuous signal at H5W)9.

The continuous signal obtained by H5W9 is supplied to the video signal processing circuit 14, restored to the original signal form, and output. At this time, in the VTR of this embodiment, the reproduction signals obtained from the heads 5a and 5b are used during normal reproduction, and the reproduction signals obtained from the heads 5a are used during still reproduction.

It is assumed that a reproduced signal obtained from Hella F' 5 c is used.

The ATF signal generation circuit 15 generates a tracking error signal that continuously indicates a tracking error between the head 5a or the head 5b and the video track using the reproduced signals from the heads 5a and 5b. The method is the well-known 4-frequency (
It shall be obtained by the viroft signal) method. What is the 4-frequency power method?' is a method in which four types of pilot signals with different frequencies are sequentially recorded for each track during recording, and the signals are obtained from both adjacent tracks of the trunk being mainly traced by the playback head. The pilot signal level comparison output is used as a tracking error signal, or furthermore, as an ATF signal.

The ATF signal obtained by the ATF signal regeneration circuit 15 is supplied to the capstan motor control circuit 8.

The capstan 6 is controlled via a capstan motor drive circuit 7. Generally, the capstan motor control circuit 8 has a phase control loop based on this ATF signal and a speed control loop that detects the rotation of the capstan 6 and keeps the rotation speed constant, but a detailed explanation will be omitted here.

On the other hand, a drum PG of 30 Hz indicating the rotational phase of the drum 6 is obtained via a detector 12 and a generator 13, and the switching timing of H3W9 is controlled by this drum PG. Further, a high frequency pulse signal (drum FG) for detecting the rotational speed of the drum 6 is obtained by a detector 10 and a generator 11.

17 is a still playback control circuit, and when a playback command is issued by the system controller 18, the above-mentioned tram P
The capstan 6 is controlled via the capstan motor control circuit 8 using G, ATF signals, etc. from when a still reproduction command is issued until when still reproduction is actually performed.

The operation of the still playback control circuit 17 will be explained in detail below. Figure 4 shows the still playback control circuit 17 in Figure 3.
It is a figure which shows one specific example. In Figure 4, 21 is AT
A terminal to which the F signal is supplied, 22 a terminal to which the drum PG is supplied, 30 a terminal to which the drum FC described above is supplied, 3
Reference numeral 1 denotes a terminal to which a control signal instructing still playback is supplied from the system controller 16. Further, 26 is a comparator, 32, 33, 34, and 35 are D-type flip-flops (DFF), 36 is an ant gate, and 37 is an output terminal for a capstan driving signal.

FIGS. 5(A) to 5(J) are timing charts showing the waveforms of each part of FIGS. 4(A) to 4(J), and the operation of each part during still playback will be explained below using these charts.

First, a control signal is supplied to the capstan motor control circuit 8 at the same time as a still playback command from the system controller 16, and the capstan motor control circuit 8 performs normal playback control, that is, speed control and phase control using the ATF signal. , the control is switched to a capstan drive signal obtained from the still playback control circuit 17.

Next, the operation of generating a capstan driving signal by the still reproduction control circuit 17 will be described. The ATF signal inputted from the terminal 21 in FIG. 4 is supplied to a comparator 26 and compared with a voltage indicating on-track. This voltage is obtained by dividing the power supply voltage Vcc by resistors R1 and R2. The output of the comparator 26 is supplied to a differentiating circuit consisting of a capacitor C1 and a resistor R5 via an inverting circuit consisting of a transistor Tl and resistors R3 and R4. The output signal of this inversion circuit is shown in FIG.

The output signals of the differentiating circuits are shown in FIG. 5(G).

The output signal (g) of the differentiating circuit is supplied to the CK terminal of the DFF 35.

On the other hand, 30PG input from terminal 22 is supplied to a monomulti including DFF32, capacitor C2, and resistors R6 and R7, where a pulse signal (d) having a pulse width to stop the tape at a desired stop position is obtained. . The pulse width of this pulse signal (d) can be adjusted by variable resistor R6.
is triggered, and this DFF33 is connected to capacitor C3 and resistor R.
8 and operates as a monomulti, and obtains a periodic signal as shown in FIG. 5(e) as its Q output.

The DFF 35 is triggered by the rising edge of the output of the differentiating circuit described above, and is reset by the Q output (E) of the DFF 33. The output signal (H) of this DFF 35 is supplied to an AND gate 36, which opens the AND gate when a still playback command is issued. signal) is supplied to the capstan motor control circuit 8 via an AND gate 36 and from a terminal 37 as a capstan drive signal (nu).

Now, it is assumed that field still is performed using heads 5a and 5c, and the ATF signal is transmitted to heads 5a and 5c.
Suppose that it is obtained from the reproduced signal of b. At this time, head 5a
If the on-trunk timing (the timing at which an upward pulse is generated in the wI output (g)) during playback matches the midpoint of the /\I level part of the 30PG for head switching (as shown in Figure 5 J). As is clear from FIG. 2, the trace loci of the heads 5a and 5b become the ideal trace locus IS.

In the above-described embodiment, the on-track timing deviates from the ideal timing by the period indicated by t2 in FIG. However, the period during which the driving pulse signal (b) is gated is the period Ll, which is longer than the period 73. In reality, even if the capstan 6 is driven by the driving pulse (b) for the period t3, the capstan 6 will not be driven, that is, the minimum required to drive the capstan during the period L2 corresponding to the phase difference. By adding the period E3, the gate period t1 is obtained. As a result, the on-track timing matches J,
The spatula l'' 5a and 5c trace on the ideal trace locus Is.

According to the VTR configured as described above, the head 5a.

Since the tape 5C can be repeatedly driven until it traces the ideal trace locus IS and minutely driven by the drive pulse, it is possible to accurately set the tape stop position to the desired stop position. Furthermore, starting the capstan, which has conventionally been an obstacle in performing such driving, can be solved by gating the drive pulse for the period necessary for starting.

In the above-described embodiment, the ATF signal obtained from the reproduced signals of the heads 5a and 5b was used when performing field still with the heads 5a and 5c. Similar operational functions can be achieved using the ATF signal obtained from the reproduced signal of 5c. It goes without saying that it can be similarly applied to a VTR that performs frame stills.For example, the pulse width of the output signal (d) of the i-no-multi including the DFF32 may be increased by l/120 seconds. Although the above description has been made regarding still playback of a VTR, it goes without saying that the present invention is also effective when it is necessary to accurately stop a tape-shaped recording medium at a desired stop position for other purposes.

Description of Effects> As explained above, according to the present invention, it was possible to obtain a recording or reproducing apparatus that can extremely accurately stop a tape-shaped recording medium at a desired stopping position.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between a recording track and a head trace locus in a VTR, and FIG. 2 is a diagram showing an envelope waveform of a reproduction signal during still image reproduction. FIG. 3 is a diagram showing a schematic configuration of a VTR as an embodiment of the present invention. FIG. 4 is a diagram showing a specific example of a still playback control circuit. FIG. 5 is a timing chart showing the waveform of the numbered part in FIG. 4 is a magnetic tape as a tape-like recording medium, 6 is a capstan, 12 is a drum rotation phase detector, and 13 is a drum P.
G generator, 15 is an ATF signal generation circuit, 17 is a still playback control circuit, 26 is a comparator, 32, 33, 34
．． 35 is a DFF, 36 is an AND gate, tl is a drive pulse generation period, and t2 is a period corresponding to the required transfer amount. t3 is a period required for starting the capstan.

Claims (1)

[Claims] A device that stops a tape-shaped recording medium at a desired stop position and performs recording or reproduction, when the medium is transported to the desired stop position by a capstan for transporting the medium in its longitudinal direction. , a record characterized in that a required transfer amount is repeatedly detected, and a number of driving pulses corresponding to the transfer amount plus a number necessary to start the capstan are repeatedly supplied to the capstan. Or playback equipment.