JPS60106021A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a special reproduced image which is free from noises by controlling the control voltage to be applied to a piezoelectric drive element so that the signal levels are set at the maximum value at plural points obtained by tracing a recording track by a mobile head and therefore absorbing the displacement of the piezoelectric drive element, the variance of sensitivity of the applied voltage and the nonlinear characteristics. CONSTITUTION:The 1-frame precedig head loci 10-1-10-3 and the new head loci 11-1- 11-3 are equal to the detecting points of the signal levels corresponding to each other. A time point t1 corresponds to the points 10-2 and 11-2, and a time point t2 is equal to the time when a track is tracked. The waveforms obtained between times points 0 and t2 of the drive voltage applied to a piezoelectric drive element 23 are divided into two straight lines of time points 0-t1 and t1-t2. Voltage comparators 17-1-17-3 compare the outputs of sample holding circuits 16-1-16-4 which hold signal levels at plural points. An applied voltage control circuit 21 controls the applied voltage in response to the results of said comparisons. Then the drive voltage approximate to a straight line of folded line is applied to the element 23 so as to set the signals of plural points at maximum levels. As a result, the head can always trace on the recording tracks.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is characterized in that a piezoelectric drive element is attached to a rotary cylinder, and a magnetic head is attached on the IE drive element. The present invention relates to a helical scan type magnetic recording and reproducing device that is capable of performing the above-mentioned heratochi tracing.

Conventional Phosphoric Acid and Its Problems In recent years, helical scan type magnetic recording and reproducing devices are required to produce clear images without noise not only during normal playback, but also during special playback such as static, low-speed, and high-speed playback.

There is a magnetic recording and reproducing device that continuously switches between four heads with different magnetic head widths during static and low-speed reproduction to obtain a noise-free screen, but noise occurs during high-speed reproduction.

In addition, a piezoelectric drive element with a magnetic head mounted on a rotating cylinder is mounted, and a drive voltage that depends on the tape speed is applied to the piezoelectric drive element to move the magnetic head in the width direction of the recording track, making it possible to trace the recording track. There are also some that provide a noise-free screen.

FIG. 1 shows the head trajectory of the above system at 5x speed. (1) is the head trajectory when playing with a head fixed to a rotating cylinder, (2)
is the head trajectory when a voltage corresponding to the track deviation is applied by the head mounted on the piezoelectric drive element, (3
a) to (3e) show track deviations. As shown in the figure, a system in which the head can be moved in one direction along the recording track using a piezoelectric drive element can provide a noise-free screen during any special playback.

FIG. 2 (at (b)) shows an example of a piezoelectric drive element. This is made of a ring-shaped LIE electromagnetic gold plate laminated together, (4a) and (4b) are piezoelectric ceramic plates, ( 5a) (5b)
is the mounting part of the piezoelectric drive element to the rotating cylinder, (6a
) (6b) represents the magnetic head, (7a) and (7b) represent the magnetic head (6a bar 6b) chisel J movement direction. FIG. 3 shows voltage waveforms applied to the piezoelectric driving elements to move the magnetic heads (6a) and (6b), respectively. Note that some piezoelectric drive elements are made by laminating a piezoelectric magnetic thin plate and a metal thin plate.

However, as shown in Figure 4, F: piezoelectric drive elements usually have variations in sensitivity depending on the element, non-linearity in the applied voltage-y position characteristic, and the signal at one point on the recording trunk as shown in Figure 5. In control that detects the level and determines the drive voltage to the piezoelectric drive element, the signal level becomes small at both ends of the recording track, resulting in deterioration of image quality. The figure shows the recorded tape and the head trajectory; (8) is the head trajectory when the sensitivity is calibrated, and (9) is the head trajectory when the sensitivity is not calibrated.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a magnetic recording/reproducing device that can absorb variations in the sensitivity of piezoelectric drive elements, such as I+ linear characteristics, and always provide clear images.

Structure of the Invention The magnetic recording and reproducing apparatus of the present invention includes a piezoelectric drive element υ attached to a rotating cylinder, a magnetic head attached to the movable part of the piezoelectric drive element, and a control chamber It applied to the piezoelectric drive element to generate the The magnetic head is configured to be able to change its position in the width direction of the recording track of the magnetic tape, and includes a detection circuit that detects the signal level at a plurality of points obtained by tracing the recording track with the magnetic head; A sample-and-hold circuit that holds the signal level, a voltage comparator that compares the output of this sample-and-hold circuit, and an applied voltage control circuit that controls the control voltage to the pressure drive element according to the comparison result are provided. 111 Signal level at multiple points) V
The present invention is characterized in that a linear or broken line drive voltage is applied to the drive element so as to maximize the drive voltage, so that the head can always trace the recording track.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will now be described with reference to FIGS. 6 to 9. FIG. 6 shows the trajectory and drive voltage waveform when the signal levels at three points on the recording track are detected. In the same figure, I0υ is 1 frame...1
head trajectory and new head trajectory, (10-1) (10
-2) (10-3) and (11-1) (11-2) (11
-3) are the detection points of corresponding signal levels, tl
is the time corresponding to the detection point (10-2) (11-2), R
2 is the time to trace one track. The time is determined by counting the FG times signal of the frequency corresponding to Schilling's rotational speed JW from 0'' every one track minute.The driving voltage in the figure is set so that the head traces the recording track. , is a polygonal voltage based on two straight lines.

FIG. 7 shows a configuration diagram of a magnetic head drive circuit that can be driven as shown in FIG. 6. Note that the following explanation will focus on the piezoelectric drive element. , l+1-digit magnetic head will be described as a Kanamachi dynamic head. R4 is a movable head configured by being attached to a piezoelectric JIF dynamic element, 1.14 is a high frequency amplifier, circle is a detection circuit, (to) is a 4-circuit switch circuit, (16-1
) to (16-4) are sample and hold circuits, (17-1
) to (17-3) are voltage comparators, (18-1) (18-
2) is a differential amplifier, Ql is a DC control circuit, (7) is a slope control circuit, 娑υ is an applied voltage control circuit, (a) is a speed detection circuit, and R1 and R2 are resistance elements that make the comparison base *WIf. be.

Fig. 8 is the timing chart of Fig. 7, where H8W is the head nuitchinda signal, S1 to S4 are the drive valve switch No. 8 of the switch element of the switch circuit σQ, and CUM 1 to C0M.
3 is pressure comparator (17-1) (17-2) (17-3)
output level) V.

Figure 9 shows the movable head μ relative to the recording trunk on the tape.
4 movement is shown. The shaded area in the figure is proportional to the signal level.

Next, the configuration will be specifically explained with reference to FIGS. 6 to 9.

If Time of the drive voltage applied to the force drive element 0~
I'11. In this example, the waveform at time O~[1 and [
It is divided into two straight lines from 1 to t2. These heavy pressures ■1, V
zbaVz = At (t-tx) + 13...
... (1) Vz = A2 (t-tx) 10B
...... (2) Similar to, in the first and second equations, t is expressed as 0 <: t <tt 1 tl 1 12.

First, the tape speed is detected by the speed detection circuit (a) by counting the FG times signal of the cab scan motor between the control signals on the recording tape. Next, the slopes A1 and A2 of the first and second equations, which are set in advance, and the DC level B are determined based on the speed, and the applied voltage waveform is determined. The head position at that time is the position shown in Figure 9 (2
4-1). The signal level at tl at this time is held by the sample and hold circuit (16-1) by closing the switch SWl of the switch circuit Q5. Next, B is increased by the step pressure determined by ΔB in the following equation by the DC control circuit 4.

B=B±ΔB (3) At this time, the head position <24-2), 1. The signal level in the 4-circuit switch circuit (151 switch SW2
Sample and hold circuit (16-2) by closing
Hold on. Next, the two signals held by the voltage comparator (17-1) are compared, and the result is output COMI.
If it is +lL" level, the DC level is increased as it is, and if it is "H" level, the DC level /l/ is changed in the direction of decrease. What does this is the DC control circuit (to). In the example, the output COM of the voltage comparator (17-1)
Since I is at the "L" level, the DC level is increased by ΔB.Next, the sample and hold circuit (16
-1) holds the next frame signal /<)V and compares it with the output value of the sample bold circuit (16-2) by the voltage comparator (17-1). Since the head position is at position (24-3), the output COM 1 as a comparison result is at the 11" level. In this way, when the output COM 1 is vibrating, the DC level continues to increase. This is due to head tracking. This is a direction that will improve.

However, the head position is (24-6)'! ! : Then, as a result of the signal level comparison at that time, the output COMI will be the same as the level of RQ. The DC control circuit U@ detects this and controls the DC level to decrease. In other words, if the comparison result is oscillating, the DC level should be applied in one direction.
However, when a new signal is held in the sample-and-hold circuit (16-2), the comparison result is ``LIT.'' When the signal reaches the LIT level, the increase or decrease in the DC level is reversed. do.

By this operation, tracking at the position corresponding to time t1 can be performed within a deviation corresponding to ±ΔB. Tip 9 B in the first and second equations is determined.

Next, determine the values around 1 for the first and second equations. When the comparison result output COM 1 becomes constant as shown above, (1
Switches SW3 and SW4k of switch circuit 05 are closed to set the signal levels at times t1' and tl'' corresponding to 0-1 bar 1l-1) and (10-3011-3) to the double hold circuit (16-3816-4). The difference between the output of the sample and hold circuit (16-2), which is the 1st level at 1 point, is calculated by the differential amplifier (1).
8-1) (18-2), and divides the power supply voltage Vcc with resistance elements R1 and R2 to create a voltage V.
S and is compared by voltage comparators (17-2) and (17-3). Within a certain range, if the comparison result outputs C0M2 and C0M3 are at "L" level, they will be at "H" level.
The slopes Al and A2 of the first and second equations are determined by the slope control circuit (20
-1) (20-2) to find the optimum value. However, the slope @A1. The control step ΔA of Az and the step ΔBJ of the DC level are kept small.

Also, in the same way as when determining the DC level at time t1, the applied driving voltage can be determined by determining the optimum DC level /l/B' at time l and t2'.

In the above embodiment, the signal level at time t1 among the three points v'i was used to determine the DC level, and the signal levels at tl' and t1'' were used to determine the slope of the straight line. The slope can be determined by using an arbitrary point among the points and using other points other than this arbitrary point.

In addition, the control in FIG. 6 [! The I signal is a polygonal or linear voltage whose nod and DC level changes depending on the playback speed, and the signal level at multiple points and the signal level at a corresponding point one frame before are compared with the voltage to generate a trace signal. It can also be obtained by determining applied voltage levels at a plurality of points so that the respective levels are maximum, and then determining all applied linear voltages using a straight line connecting the applied voltage levels.

As described in the detailed description of the invention, the magnetic recording/reproducing apparatus of the present invention includes a detection circuit that detects the signal level/L/all at a plurality of points obtained by tracing a recording track with a movable head, and a 1G signal level at the plurality of points. A sample-and-hold circuit that holds the level, a voltage comparator that compares the output of this twin-hold circuit, and an applied voltage control circuit that controls the control voltage to the piezoelectric drive element according to the comparison result t are provided. It is possible to control the voltage applied to the piezoelectric drive element so as to maximize the signal level at the plurality of points, and it is possible to absorb variations in sensitivity and nonlinear characteristics of the displacement-applied voltage of the piezoelectric drive element.
This provides a noise-free special reproduction surface.

[Brief explanation of drawings]

Figure 1 is a diagram of the running trajectory of the fixed head and the 11J' moving head on the tape, Figure 2 is a top view and side view of the laminated piezoelectric drive element, and Figure 3 is the voltage waveform applied to the piezoelectric drive element. Figure 4 is a displacement-applied voltage characteristic diagram of the electric drive element, Figure 5 is a trajectory diagram of the movable head when the sensitivity of the pressure-torque drive element is not corrected, and Figures 6 to 9 are An embodiment of the present invention is shown, and FIG. 6 is a head trajectory and applied voltage waveform diagram when signal level lv at three points is detected, and FIG.
0tsuk diagram, Figure 8 is the timing chart diagram of Figure 7, Figure 9
The figure is an explanatory diagram of the movement of the head on the recording track. Rice cake...movable head, C14...detection circuit, song...
Switch circuit, (16-1) to (16-4)... Sun full hold circuit, (17-L) to (17-3)...
Voltage comparator, (18-1) (18-2)... Differential amplifier, (11... DC control circuit, (20-1) (20-
2)...Inclination control circuit, Nυ...Applied voltage control circuit, (A)...Speed detection circuit, ■...Piezoelectric drive element representative Yoshihiro Morimoto Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. This E
A magnetic head is attached to a movable part of the piezoelectric drive element, and a control voltage is applied to the piezoelectric drive element to change the position of the magnetic head in the width direction of the recording track of the magnetic tape. a detection circuit that detects signal levels at multiple points obtained by tracing a recording track, a sample hold circuit that holds the signal levels at the multiple points, a voltage comparator that compares the output of the sample hold circuit; A magnetic recording and reproducing device is provided with an applied voltage control circuit that controls the piezoelectric drive element (Ill voltage) according to the comparison result. A patent characterized in that the voltage is a polygonal line or a straight line where the DC level changes, and an arbitrary point among the signal levels at multiple points is used to determine the DC level, and signal levels at other points are used to determine the slope of the straight line. Claim 1
The magnetic recording and reproducing device described in . 3. The direct current level of the control voltage is determined so that the trace signal level of the drive voltage of the piezoelectric drive element becomes the maximum based on the comparison result of the trace signal level of the corresponding point one frame before, and the After the DC level that gives the signal level is determined, the electric lth ratio between the No. 18 level and the signal levels at the plurality of points is softened so that the signal level at the other points is maximized. A magnetic recording endogenous device according to claim 2, characterized in that it is configured to determine the nod of the control voltage. 4. The control dragon If to the 1f electric drive element is a polygonal line or a linear voltage whose slope and DC level change according to the endogenous speed, and the number 100 level at multiple points and the corresponding point in one frame n1■ are A patent characterized in that the voltage levels to be applied at multiple points are determined by voltage comparison of signal levels so that each trace signal level becomes maximum, and the applied voltage levels are determined by a straight line connecting the applied voltage levels. Shimizu range 1
The magnetic recording and reproducing device described in .