JPS60219682A - Picture reproducing device - Google Patents

Abstract

PURPOSE:To obtain a picture with high quality by controlling the circuit that a reproducing head output at the former and latter period of a displacement period has nearly the same time when the output is less than a prescribed time. CONSTITUTION:When the displacement center of the reproducing head 5 is located at the center of the 1st and 2nd tracks 3, 4, the time when the output of the reproducing head 5 at the first and latter half of the period moving from one track to the other is lower than the output of a reference value generating circuit 10 is nearly the same for the both. Then an output value of a u/D circuit 10 when a latch pulse 19 is generated is the same as the initial value of the u/D circuit 16. When the center of displacement is shifted in the direction of the 1st track 3, since much output of the comparator circuit 9 is generated in the period of (u) of the u/D signal 17, the output of a gate circuit 23 is positive to the initial value of the u/D circuit 16 and the center of the displacement is corrected in the direction of the 2nd track 4. Thus, no jitter is produced in the reproducing and the reproducing head outputs from the two tracks are nearly the same and a picture with high quality is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a reproducing device using a recording/reproducing medium such as a magnetic sheet, and in particular, it continuously reproduces still images recorded on two adjacent trunks of a plurality of concentric recording tracks. The present invention relates to an image reproducing device that reproduces images.

Conventional structure and its problems A recording/reproducing medium having a plurality of concentric recording tracks (
When one image signal recorded on two adjacent tracks of a sheet (hereinafter referred to as "sheet") is alternately played back from both tracks by displacing the position of the playback head in a pulse-like manner for each rotation of the sheet, the playback head output is In the process of performing demodulation and other processing to convert into an image signal, if the playback head outputs between the two tracks differ, flickering will occur in the reproduced image signal, so the playback head outputs from the two tracks are almost the same. things are desirable.

Therefore, conventional devices are currently configured so that the playback head traces the track correctly using opening control, etc., but in this case, the playback head is vibrated at several 1001-lx, which causes jitter in the playback image signal. There was a problem that occurred.

There is also a method of controlling the center of displacement in which the position of the reproducing head is displaced in a pulse-like manner so that the magnitudes of the reproduction outputs from the two trunks are compared and the two outputs are approximately the same. However, in this method, while comparing the sizes, the playback head output decreases even if the position shifts toward the outer circumference of the sheet or toward the inner circumference of the sheet relative to the track position. It is necessary to vibrate. Therefore, as with the conventional method, there is a problem that jitter occurs in the reproduced image signal.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an image reproducing apparatus that is equipped with a control system that makes the reproducing head outputs from two tracks the same without causing jitter in the reproduced image signal, and that can obtain high-quality images.

Structure of the Invention The present invention takes advantage of the fact that the playback head output decreases during the period in which the position of the playback head is displaced from one track position to the other trunk position. The center of displacement of the reproducing head is controlled in a pulse-like manner so that the two times become approximately the same by comparing the time during which the value falls below a predetermined value.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 is a block diagram of an image reproducing apparatus according to an embodiment of the present invention. In the figure, a seat 2 rotated by a seat motor 1 has a plurality of concentric recording tracks, and adjacent first trunks 3. The image signal recorded on the second track 4 is transmitted to the reproducing head 6 by alternately displacing the position of the reproducing head 6 between the first track 3 position and the second track 4 position for each rotation of the sheet 2. The output of the preamplifier circuit 6
After being amplified, the signal passes through a demodulation circuit 7 and is reproduced.

The output of the preamplifier circuit 6 is subjected to envelope detection in a detection circuit 8, and is compared with the output of a reference value generation circuit 10 in a comparator circuit 9. The output is inputted to a first clock signal 12 outputted from a pulse generation circuit 11. It is used as a control signal for the first gate circuit 13.

The output of the first gate circuit 13 is a control signal that controls the first pulse signal 14 that is output during the period when the reproducing head 6 moves from the first track 3 position to the second track 4 position and during the period when it moves in the opposite direction. The output is input to the clock terminal of the addition/V subtraction (hereinafter referred to as u/D) circuit 16. Also u/D circuit 1
The playback head 6 is connected to the u/D terminal of 6 for the first track, 3
The first half of the period of movement from the position to the second track 4 position (inner circumferential direction) is addition (hereinafter referred to as U), the second half is subtraction (hereinafter referred to as below), and the movement is in the opposite direction (outer circumferential direction). The u/D signal 17 switches to D in the first half and to U in the second half.
is input. In addition, the initial value setting (hereinafter referred to as P) terminal contains the u/D circuit 1 before the playback head 6 starts moving.
A P signal 18 for setting the initial value of 6 is input. The output of the U/D circuit 16 is latched into the latch circuit 20 by the launch pulse 19 generated when the reproducing head 6 completes moving from one track to the other track.

Therefore, the latch output of the latch circuit 2o is
The preamplifier circuit 6 and the detection circuit 8 amplify and detect the output of the reproducing head 6 in the first and second half of the period in which the signal moves from one track to the other, and the output is the output of the reference value generation circuit 1o. A value corresponding to the difference in period that is smaller than that becomes the value added or subtracted from the initial value of the u/D circuit 16.

The output of this latch circuit 2o is converted into an analog value by a D-AX conversion circuit 21, and is converted into an analog value by a low-pass circuit 22. It passes through the third gate circuit 23 and is added to the second pulse signal 25 corresponding to the position of the reproducing head 6 which is displaced for each rotation of the sheet 2 from the pulse generating circuit 11 in the adding circuit 24, and its output is The signal is amplified by an electro-mechanical transducer (hereinafter referred to as bimorph) drive circuit 26 and applied to a bimorph 27 that displaces the position of the reproducing head 6 . The bimorph 27 is used when the position of the playback head 5 is slightly displaced to the extent of pinching an adjacent trunk, and the motor 28 is used when the position of the playback head 5 is to be greatly displaced.

Further, the rotational position detection element 29 detects leakage magnetic flux of the magnet 30 rotating together with the seat 2, and its output is inputted to the pulse generation circuit 11 as a synchronization signal.

Note that the system control circuit 31 has a function of controlling the entire device.

FIG. 2 is a waveform diagram of each part of Ω when the center of displacement of the reproducing head 6 of the image reproducing apparatus of FIG. 1 is located at the center of the first track 23 position and the second track 4 position.

In this case, the time during which the output of the reproducing head 6 falls below the 1° output of the reference value generation circuit in the first half and the second half of the period in which the reproducing head 6 moves from one track to the other track is approximately the same. Therefore, when latch pulse 19 occurs, u/
The output value of the D circuit 16 becomes the same as the initial value of the u/D circuit 16. Therefore, the signal input from the gate circuit 23 to the adder circuit 24 indicates that the initial value of the U/D circuit 16, that is, the center where the reproducing head 6 alternately shifts to both track positions, is not corrected.

Here, if the center of this transition shifts in the direction of the first track 3 position, the output of the comparator circuit 9 will have a large amount of the u/D signal 17 generated during the period U, so the output of the gate circuit 23 will change to the u/D signal 17. The value is in the positive direction with respect to the initial value of the /D circuit 16, and the center of displacement is corrected in the direction of the second track 4.

Therefore, if there is a shift in the opposite direction, it is natural that it is corrected in the direction of the first trunk 3.

In FIG. 1, a signal is created using the U/D circuit 16, etc., comparing the first and second periods when the playback head 6 shifts and the period during which the output of the playback head 6 at K is lower than the output of the reference value generation circuit 1o. However, in other methods, for example, in the period in which the output of the comparator circuit 9 in Fig. 2 is generated, when the u/D signal 17 is U, it is positive, when it is D, it is negative, and in other periods it is zero. A similar signal can be obtained using a method of creating a signal.

Further, similar functions can be obtained in other systems in which the output of the reference value generating circuit 10 is varied in accordance with the output of the reproducing head 6 during a period in which the reproducing head 6 is not performing a displacement operation.

Effects of the Invention According to the present invention, there is no jitter in the reproduced signal, the reproduction head outputs from the two tracks are approximately the same, and a high quality image can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an image reproducing apparatus according to an embodiment of the present invention, and FIG. 2 is a waveform diagram of each part thereof. 1... Seat motor, 2... Seat, 3
...First track, 4...Second track, 6:...Playback head, 8...Detection circuit, 9...Comparison Circuit, 1°...Reference value generation circuit, 11...Pulse generation circuit, 16...
... u/D circuit, 17... u/D signal, 19
...D-A conversion circuit, 24 ... Addition circuit, 26
. . . Second pulse signal, 26 . . . Bimorph drive circuit, 27 . . . Bimorph.

Claims (1)

[Claims] (1) The reproducing head position is alternately displaced to two adjacent track positions of a recording/reproducing medium having a plurality of concentric tracks, and the above-mentioned operation is performed in the first half and the second half of the period in which the head moves between the tracks. An image reproducing device characterized in that information on a difference in time at which the output of the head decreases by a predetermined value is used as a control signal for correcting the center of the displacement in the track width direction. (b) The image reproducing apparatus according to claim 1, wherein the predetermined value is set according to the output of the reproducing head.