JPS6059520A - Recording or reproducing device - Google Patents

Abstract

PURPOSE:To uniform the displaced variables of two electromechanical conversion elements at the switching of a mode and to attain fine recording and reproducing by shifting the switching timing of pattern signals for controlling impressed voltages by a period corresponding to a phase difference. CONSTITUTION:Respective heads 4, 5 are fitted and two electromechanical conversion elements 2, 3 having residual displacement characteristics are displaced to execute recording or reproducing. When the elements 2, 3 are switched between two modes in accordance with the same or similar prescribed pattern signals having a phase difference with each other, the switching timing of the pattern signals controlling the voltages to be impressed to the elements 2, 3 respectively are shifted by a period corresponding to the phase difference at least in one mode. Consequently, the displaced variables of the elements 2, 3 can be uniformed and fine recording and reproducing can be attained.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a recording or reproducing device, and more particularly to a device that performs recording or reproducing using a head attached to each of two electro-mechanical transducers having residual displacement characteristics. .

<Description of the Prior Art> In recent years, in the field of magnetic recording, a magnetic head is attached to an electro-mechanical transducer, and the position of the magnetic head is changed by driving the electro-mechanical transducer, thereby achieving a desired position on a recording medium. Nowadays, it has become common to record or play back.

As the electro-mechanical conversion element mentioned above, for example, a bimorph type piezoelectric ceramic element (hereinafter simply referred to as bimorph) is used. Such elements generally have residual displacement characteristics. This residual displacement characteristic will be briefly explained below. FIG. 1 is a diagram showing the characteristics of the voltage applied to the bimorph and the amount of displacement corresponding thereto. As is clear from the characteristic diagram of FIG. 1, for example, even if the same applied voltage is applied to the bimorph, the amount of displacement of the bimorph will vary depending on the previous movement of the bimorph by an amount corresponding to the characteristics. Due to this residual displacement characteristic, bimorphs etc.
In a magnetic recording or reproducing device using a mechanical transducer, the following problems occur.

The problems caused by the above-mentioned residual displacement characteristics will be explained below by taking a rotating two-handed helical scan type magnetic recording and reproducing apparatus (hereinafter referred to as VTR) as an example.

FIGS. 2A to 2C are diagrams for explaining problems caused by residual displacement characteristics of electromechanical transducers in conventional VTRs. FIG. 2(A) is a diagram showing the structure of a rotating head drum in a VTR. In Figure 2 (A), l
is a rotating drum, 2 and 3 are bimorphs, 4.5 is a head mounted on the bimorphs 2 and 3, respectively, and 6 and 7 are arrows indicating the displacement direction of the heads 4 and 5, respectively. At this time, it is assumed that when the displacement amounts of the bimorphs 2 and 3 are equal, the heads 4 and 5 are configured to rotate on the same plane. It is also assumed that the heads 4.5 have the same magnetization direction.

In FIG. 2(B), 13 is an arrow indicating the running direction of the magnetic tape 8. During normal recording, the tape is run at a predetermined speed in the direction of the arrow 13, and the magnetic tape is moved in the direction shown by the solid line 9. A trace line 9 of the heads 4 and 5 indicates the center line of the recording track. If the tape 8 is stopped now, the head 4.5 will race in the direction shown by the dashed line lO, and if the tape is run at four times the normal recording speed, the head 4.5 will The trajectory to be traced is in the direction shown by the two-dot chain line 11.

When performing a so-called high-speed search or still playback by making the running speed of the tape different from that during normal playback, a noise-free playback screen can be obtained by controlling the bimorph and displacing the head as shown by arrow 12. It is something that can be done. FIG. 2(C) is a timing chart showing the timing of applying the voltage to the bimorphs 2 and 3 during the quadruple speed search in such a case. Figure 2 (
The waveform shown in (a) of C) is a signal related to the rotation of the drum l, and when it is at a low level (period indicated by A in FIG. It is assumed that during the period indicated by B in FIG. 2(C), the heads 5 are respectively traversing the magnetic tape. In addition, (b) in FIG. 2(C) shows the voltage applied to the bimorph 2 to displace the head 4;
(C) in FIG. 2(C) is a voltage applied to the bimorph 3 to displace the head 5. However, in (b) and (C) of FIG. 2 (G), when the heads 4 and 5 are actually tracing on the magnetic tape 8, the part that controls the heads 4 and 5 is the part on the lower right. This is the waveform of

Now, suppose that there is an instruction to return from quadruple speed search to normal playback at the moment indicated by tl in the second IN (C). At this time, the displacement amounts of the bimorphs 2 and 3 must be made equal, and the positions of the heads 4 and 5 in the directions of arrows 6 and 7 (hereinafter simply referred to as head heights) must be made equal. However, as shown in FIG. 2(C), the re-applied voltage is set to zero from the next zero-crossing point of the re-applied voltage, or 1. If the reapplied voltage is set to zero at the instant of , bimorph 2 will move from point A to point A' shown in
, Bimorph 3 changes its state from point B to point B', so the head height cannot be adjusted, resulting in the deviation shown at 21b in Figure 1. Therefore, even during normal playback, the head is always There is a height discrepancy, making it impossible to trace the track well.

Conventionally, in order to eliminate the influence of this residual displacement characteristic, it has been considered to apply an alternating voltage applied to the bimorph that gradually attenuates so that the state of the bimorph converges to the zero point in FIG. 1. However, according to this method, it is necessary to create an applied voltage that gradually attenuates, resulting in a complicated circuit configuration. Furthermore, this method takes too much time to eliminate the effects of residual displacement characteristics. In other words, if we try to converge the state of both bimorphs from the state shown at point A or B in Figure 1 to the zero point, it will take a certain amount of time. It was impossible to equalize the amount of displacement. Considering the example of FIG. 2, this means that when switching from high-speed search playback to normal playback, the head becomes completely useless for a while, making it impossible to obtain a good playback screen.

<Object of the Invention> In view of the two drawbacks, the present invention provides a recording or reproducing device that can instantaneously equalize the displacement amount of two electro-mechanical conversion elements having residual displacement characteristics when switching modes. The purpose is to

<Description of Examples> The present invention will be described in detail below using Examples. Third
The figure is a diagram showing the circuit configuration of a bimorph control system of a VTR as an embodiment of the present invention, and FIG. 4 is similar to FIG. 3(a).
-(i) It is a waveform diagram showing the waveform of each part. In FIG. 3, numerals 2 and 3 are bimorphs arranged as shown in FIG. 2(A), and numerals 4 and 5 are magnetic heads arranged as shown in FIG. 2(A). 20 is a mode selector consisting of an operation button, etc.; 21, 22 is a circuit that generates a triangular pattern of applied voltage to be supplied to the bimorphs 2 and 3 according to the mode selector 20; 23, 24, 25; and 26 are shown in the figure, respectively. An analog switch 27 is turned on and off by input to a control terminal indicated by an arrow, and 27 is a drum 21 shown in FIG. 2(A).
30Hz square wave signal (hereinafter referred to as 30PG) according to the rotation of
28 is a mono multi-vib break that forms a 60Hz rectangular wave signal as shown in FIG.
31 are AND gates, 32 and 33 are D-type flip-flops (DFF), 34 and 35 are low-pass filters (LPF), and 36 and 37 are amplifiers. It is assumed that the recording/reproducing circuit is provided separately.

Below, when performing normal playback on this VTR, 4
The operation of each part when performing double-speed high-speed search and then returning to normal playback will be explained. An, Bn (n
It is assumed that the periods indicated by (integers) are the periods during which the heads 4'EI and 5 are tracing the magnetic tape.

When the mode selector 20 issues a command to start the high-speed search reproduction mode at the moment of τl shown in FIG. 4, the output (e) of the mode selector 20 changes to a high level. By the way, 30' and 31 are the DFF outputs of the mono multi 28 when the 30PG is at low level and high level, respectively.
32 and 33 clock input terminals. The output of the AND gate 31 is shown in FIG. 4(C), and the output of the AND gate 30 is shown in FIG. 4(D). Each of the DFFs 32 and 33 sets the Q output to high level at the first set timing (indicated by τ3 and τ2 in the figure) after the output (e) of the mode selector 20 changes to high level. Therefore, the switch 23 is turned on at τ2, and the switch 24 is turned on at τ3. On the other hand, according to this, switch 2 at τ2
5, the switches 26 are turned off at τ3.

If τ1 is at the timing shown in FIG. 4, first, at τ2, the potential at point (h) changes from O[V] to the output voltage of the triangular pattern generation circuit 21. At this time, since the head 4 is not tracing on the tape, no image disturbance occurs due to this switching. Further, at τ3, 1/80 second later, the phase difference between both triangular patterns is reached and the potential at the (+) point changes from O[V] to the output voltage of the triangular pattern generating circuit 22.

In this case as well, the head 5 is not tracing the tape.

Therefore, the changes in the applied voltages supplied to the bimorphs 2 and 3 always have exactly the same pattern, with only a difference in phase. In other words, considering the states of both bimorphs even during high-speed search playback, the state of one bimorph always tracks that of the other bimorph on the characteristic diagram in Figure 1, and the two bimorphs Since they move in exactly the same way, the displacement amounts of the two heads can always be made equal with a certain phase difference, and good high-speed search and playback can be performed.

Next, when the mode selector 20 cancels the high-speed search playback mode and commands the normal playback mode at the moment indicated by τ4, both the D inputs of the DFFs 32 and 33 turn to low level. DFF33 is τ.

The Q output is changed to low level at the first set timing 5, and the DFF 32 also changes the Q output to low level at the first set timing τ6 from τ4. At this time also τ5. τ
The time difference of 6 corresponds to the phase difference between both triangular patterns. τ5
At this point, the output of the DFF 33 also changes to high level, the switch 23 is turned off, the switch 25 is turned on, and the potential at point (h) is fixed at 0 [V]. Further, at τ6, the output of the DFF 32 changes to a high level, so the switch 24 is turned off and the switch 26 is turned on, so that the potential at point (i) is fixed at O[V]. As mentioned above, 5. Even at τ6, the heads 4 and 5 do not trace the magnetic tape, so there is no adverse effect on the reproduced image.

As mentioned above, when switching from the high-speed search reproduction mode to the normal reproduction mode, the change in the applied voltage supplied to the bimorph 2.3 only differs in phase, and the pattern can always be exactly the same. Therefore, the relative head heights of the two heads can always be made the same during high-speed search playback and normal playback after mode cutting, and good high-speed search playback and normal playback can be performed.

FIG. 5 is a diagram showing the head configuration of a VTR as another embodiment of the present invention. In FIG. 5, reference numerals 41 and 42 indicate magnetic heads, which have azimuth angles different from each other by 1 as shown, and are mounted on a rotating cylinder (not shown) with a phase difference of 180'. Also, 43.44 are bimorphs, with heads 41.42 and 43.44, respectively.
is held.

Let us consider variable speed playback in a VTR with such a configuration. Figure 6 is a diagram showing how the head traces on the tape when performing high-speed search playback in the VTR whose head configuration is shown in Figure 5. In FIG. 6, 45 is the center line of the track recorded by the head 41 or a head having the same azimuth angle as the head 41, and 46 is the center line of the track recorded by the head 42.
Alternatively, it is the center line of a track recorded by a head having the same azimuth angle as head 42. 47 is the voltage applied to the bimorph 43 during 4x search playback.
V] The center line of the scanning trajectory of the head 41 when 48
is the center line of the scanning locus of the head 42 when the voltage applied to the bimorph 44 is 0 [V].

FIG. 7 is a diagram showing the voltage pattern signal 2 applied to the bimorphs 43 and 44 during quadruple speed search in this VTR. In Figure 7, 51 is bimorph 4
Voltage pattern signal applied to 3, 52 is bimorph 44
The voltage pattern signal to be applied to is shown. Also, A is head 4
1 indicates a period in which a reproduced signal is obtained, and B indicates a period in which a reproduced signal is obtained from a spatula 42, respectively. In other words, the actually necessary applied voltage pattern is from point p to point q and from point r to point S. However, by using the applied voltage pattern as shown in FIG. 7, the direct current component becomes zero, and aging of the bimorphs 43 and 44 can be prevented. Furthermore, the present invention can be applied as follows.

FIG. 8 is a diagram showing a circuit configuration of a bimorph control system of a VTR as another embodiment of the present invention corresponding to the head configuration shown in FIG. 5. Components similar to those in FIG. 3 are given the same numbers. In FIG. 8, 53 and 54 are level comparison circuits, 55 and 56 are DFFs, and 57 is a three-man OR gate.

The following describes the operation of each part when this VTR performs a 4x speed search during normal playback and then returns to normal playback. Figure 9 shows Figures 8 (a) to (k).
5 is a timing chart showing waveforms of various parts.

When the mode selector 2° commands the start of the high-speed search reproduction mode at time tl shown in FIG. 9, the output (b) of the mode selector 2o changes to a high level. Further, from the moment tl, the triangular pattern generating circuits 21 and 22 begin to generate outputs as shown in FIG. 7, 51 and 52, respectively. The level comparison circuits 53 and 54 compare the output voltages of the triangular pattern generating circuits 21 and 22 with the 0 level, and
The structure is such that when the output voltage of 1.22 becomes smaller than O[V], a high level output is output.

Therefore, the DFFs 55 and 56 are the triangular pattern generating circuits 21.
The input will be sampled when the output voltage of 22 changes from negative to positive.

In this way, at the moment shown at t2 in FIG. 9, the Q output (g) of the DFF 55 changes to high level, and the distortion output changes to low level. Therefore, at this moment, the switch 23 is turned on and the switch 25 is turned off, and the Noveimorph 43 has the LPF 34,
A triangular pattern voltage begins to be supplied via amplifier 36. Since the radar 41 is not tracing on the tape at this time, no image disturbance occurs due to this switching. The next moment when tracing the tape begins (9th
(as shown in FIG. E3), the tape running speed is switched.

By doing so, the timing of switching the tape running speed and the timing of switching to driving the bimorph in a triangular pattern completely coincide.

Next, at the moment when the output of the triangular pattern generating circuit 22 exceeds 0 [V] (indicated by t4 in FIG. 9), the output of the 0FF56 is inverted, and from this moment on, the output voltage of the triangular pattern is also applied to the bimorph 44. start. Of course, at this time, the head 44 is not tracing the tape 2, and no image disturbance occurs.

In this way, when switching from normal playback mode to high-speed search playback mode, the displacement state of one head can be made equal to the displacement state of the other head with a certain phase difference even in the five-head configuration shown in FIG. Therefore, there is no relative height deviation of the head, and good high-speed search and playback can be performed.

Next, at the moment shown at t5, when a command is issued by the mode selector 20 to cancel the high-speed search mode and enter the normal reproduction mode, the D inputs of the DFFs 55 and 56 both turn to low level. At the next sampling of DFF55 (9th
t6), the Q output of the DFF 55 changes to a low level, and the supply of the triangular pattern for high-speed search and reproduction to the bimorph 43 ends. At this moment, the head 42 is tracing the tape, but when the head 42 finishes tracing, the tape running speed is returned to the normal speed by a servo circuit (not shown). (The moment shown at E7 in FIG. 9) Immediately after t7, the head 41 performs normal playback tracing, and at the time of the next sampling of the DFF 56 (shown at 70 in FIG. 9), the triangular pattern voltage is also supplied to the bimorph 44. will be stopped. Also, at t8, the Q output (g) of DFF55, DFF56
Since the Q output (h) of the mode selector 20 and the output (b) of the mode selector 20 are all at low level, the output (i
) also changes to low level and the triangular pattern generation circuit 21.22
It also stops the generation of triangular patterns.

As mentioned above, even in a VTR with a head configuration as shown in FIG. 5, the bimorph displacement pattern is the same, so the head height is always the same during normal playback.
Moreover, the range of change in head height and the average height can be made equal during high-speed search reproduction, and good reproduction can be performed.

It should be noted that VTRs with head configurations other than those shown in the above two embodiments
The present invention can also be applied to. For example, recording is performed by sequentially forming adjacent tracks using two heads with different azimuth angles, and for reproduction, two heads with the same azimuth angle as one of the recording heads are used, and these heads are connected to a bimorph L. The present invention can also be applied to a type of VTR that performs special playback by tracing only the tracks formed by one of the recording heads. In this case as well, the triangular patterns applied to the two bimorphs may be the same or similar, and the switching timing of the triangular patterns may be shifted in accordance with the phase difference.

In addition, although the above embodiment describes switching between high-speed search playback mode and normal playback mode, switching between high-speed search playback mode and slow motion playback mode,
Alternatively, when switching between slow motion playback mode and normal playback mode, by applying the present invention and making the application state of the triangular pattern the same before and after switching, the head height can be kept the same during normal playback. Furthermore, during variable speed playback, the displacement patterns of the bimorphs can be made the same. However, when switching between the high-speed search playback mode and the slow-motion playback mode, the phase difference between the triangular patterns applied to the two heads in both modes often differs from each other.

In this case, a predetermined voltage (for example, Ov) may be applied to one of the bimorphs for a predetermined period of time.

<Description of Effects> As explained below using the L embodiment, according to the present invention, switching between two modes in which the electro-mechanical transducer is operated by two electromechanical transducer pattern signals in at least one mode is performed. Since the two electromechanical transducers can be driven in the same state even after the recording or reproducing operation, good recording or reproduction can be performed.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the applied voltage to the bimorph and the characteristics of the displacement amount in response to it. Figures 2 (A) to (C) show the problems caused by the residual displacement characteristics of the electro-mechanical conversion element in conventional VTRs. Figure 3 is a diagram showing the circuit configuration of a bimorph control system of a VTR as an embodiment of the present invention, Figure 4 is a timing chart showing the waveform of the numbered part in Figure 3, and Figure 5 is a diagram for explanation. FIG. 6 is a diagram showing the head configuration of a VTR9 as another embodiment of the present invention. FIG. 7 is a diagram showing a voltage pattern applied to the bimorph during 4x speed search, and FIG. 8 is a diagram showing bimorph control of a VTR as another embodiment of the present invention corresponding to the head configuration shown in FIG. 5. A diagram showing the circuit configuration of the system. FIG. 9 is a timing chart showing the waveform of the part numbered in FIG. 8. 2.3 is a bimorph as an electro-mechanical conversion element,
4 and 5 are heads, 20 is a mode selector, 21.2
2 are triangular pattern generation circuits, 23.24.25.2
6 is an analog switch, 28 is a mono multi, 29 is an inverter, 30.31 is an AND gate, 32.3
3 is each DFF, 41.42 is each head, 43.44
are bimorphs, 53 and 54 are level comparison circuits, and 55
．． 56 is OFF, and 57 is OR gate 0.

Claims (1)

[Claims] 1) A device that performs recording or reproduction by displacing two electromechanical transducers each having a head attached thereto and having a residual displacement characteristic, and in at least one mode, the above-mentioned two
When switching between two modes in which each of the two electromechanical transducers is operated in response to the same or similar predetermined pattern signals having a phase difference from each other, the two electromechanical transducers are switched between two modes.
A recording or reproducing device characterized in that the switching timing of the pattern signal that controls the voltage applied to each of the mechanical transducer elements is shifted by a period according to the phase difference.