JPH0524715B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention provides an image signal of a first field recorded in a first recording area of a recording medium;
By sequentially reproducing from the recording medium the image signals of the second field recorded in the second recording area which is independent from the recording area of , one frame is made up of the reproduced image signals of two fields. This invention relates to an image signal reproducing device that obtains a reproduced image signal for 10 minutes.

(Prior Art) In recent years, electrophotographic systems have been devised in which still images are recorded using a rotating magnetic sheet as a medium, and the still images are reproduced and viewed on a television monitor or directly printed out using a printer.

In such a device, when a still image is recorded on a rotating magnetic sheet, the rotating magnetic sheet is rotated at a constant number of revolutions, and one field of one frame of the TV signal is formed on one track formed on concentric circles. There are two different types of signals:
There are two tracks each recording one field of signal. In the former case, a 1/2H delay line is used during reproduction, and one frame of reproduced signal is obtained from one field of signal. In the latter case, field signals obtained from two different tracks are sequentially reproduced to obtain a reproduced signal of one frame as a whole. FIG. 1 shows a conventional example.
H ₁ and H ₃ are playback heads, which are placed on different tracks. Reproduction amplifiers 1 and 2 amplify weak signals obtained from the reproduction heads 1 and 2. 3 is a changeover switch, which controls the playback head.
Connected to H ₁ and H ₂ for selective switching. 4 is a signal processing circuit which connects the reproduction head H ₁ ,
This is a circuit that demodulates and processes the signal obtained by _H2 . 5 is a CRT display which receives signals from the signal processing circuit 4 and monitors reproduced images. Reference numeral 6 denotes a magnetic sheet driving motor that drives the magnetic sheet 7 at a constant rotation speed. 8 is PG
It is a detection head and detects the rotational phase of the magnetic sheet.

In the above configuration, two field signals recorded on two different tracks are sent to each playback head.
Regenerated by H ₁ and H ₂ . At this time, the drive motor 6 is driving the magnetic sheet 7 at a constant rotation speed, and the PG detection head 8 receives a pulse once per rotation to detect the rotational phase of the magnetic sheet 7.

On the other hand, field signals reproduced by the reproduction heads H ₁ and H ₂ are amplified by reproduction amplifiers 1 and 2 and supplied to a changeover switch 3. The changeover switch 3 receives the signal from the PG detection head 8, and is switched every rotation of the magnetic sheet, and the signals from the playback heads _H1 and _H2 are sequentially supplied to the signal processing circuit 4 and displayed on the CRT display 5. It is then monitored.

In the conventional playback method configured as above,
There is no problem if the field signals recorded on both tracks are reliably recorded and reliably reproduced by the playback head during playback, but if one track is recorded due to instability of the head touch during recording, etc. If one track is not recorded or the other track is not reproduced in the same way, the signal recorded on the other track will not be reproduced satisfactorily, resulting in a distorted image on the CRT display.

(Objective) The present invention aims to eliminate the drawbacks of the above-mentioned conventional example.

(Embodiment) FIG. 2 shows an embodiment of the present invention, in which the same reference numerals as in FIG. 1 are the same as in the first embodiment. 9 is an open/close switch, which is normally closed. Reference numeral 10 denotes a changeover switch, which switches between the frame mode signal processing circuits 4' and 11 as necessary. Reference numeral 11 denotes a field mode signal processing circuit, which is a signal processing circuit for synthesizing frame signals when the signal from the reproduction head is for only one field. The changeover switch 10 is normally connected to the circuit 4'. 12,
13 is an on/off switch. Envelope detection circuits 14 and 15 are connected to the outputs from the reproduction amplifiers 1 and 2, respectively. Comparators 16 and 17 compare the outputs of the envelope detection circuits 14 and 15 with the reference level 18. comparator 16,
The output of R-S flip-flop 19,2
Connected to the 0 set terminal. Reference numeral 21 denotes a reset signal connected to a reset terminal, and is configured to be generated in conjunction with, for example, movement of the head. The outputs of flip-flops 19 and 20 are both connected to an OR circuit 22 and an OR circuit 23, respectively. 24 is a display means. Open/close switch 1
2 is switched by the output of the flip-flop 19, the on-off switch 13 is switched by the output of the flip-flop 20, and the on-off switch 9 and changeover switch 10 are switched by the output of the OR circuit 23.

In the above configuration, the signals reproduced by the reproduction heads H ₁ and H ₂ are amplified by the reproduction amplifiers 1 and 2,
Envelope detection circuits 14, 15 and switch 3
supplied to

The outputs from the detection circuits 14 and 15 are sent to comparators 16,
At this time, when both reproduction outputs are higher than the reference level, the outputs of the comparators 16 and 17 become "Low" level, and the R-S flip-flop 1
The outputs of 9 and 20 also become "Low" level. Then, the on/off switches 12 and 13 remain open. Also, the output of the OR circuit 22 is "Low", and the display circuit indicates that the playback output status of both heads is OK.
.

On the other hand, the output of the OR circuit 23 also becomes "Low" level, the on/off switch 9 is closed and the changeover switch 10 is connected to 10a. Therefore, when both head outputs are above the reference level, both playback outputs are set by changeover switch 3 in the same way as in Figure 1.
The signal is sequentially switched by the PG detection head 8 and is supplied to the frame mode signal processing circuit 4' via the open/close switch 9 and the changeover switch 10, and is reproduced on the CRT display 5.

Next, if one of the two playback outputs does not reach the reference level or higher due to a bad head touch during recording or playback, for example, if the output of playback head 2 is like that, the comparator 17 The output of the R-S flip-flop 20 becomes a "High" level, and accordingly, the output of the R-S flip-flop 20 also becomes a "High" level. On the other hand, since the output of the reproduction head 1 has reached the reference level or higher, the output of the flip-flop 19 is at the "Low" level as described above. Switch 12 is therefore closed by the output of flip-flop 20, and switch 13 remains open by the output of flip-flop 19. The output of the OR circuit 22 becomes "High" level, and the display 24 indicates that the output state of the head is abnormal. The output of the OR circuit 23 also becomes a "High" level, so that the open/close switch 9 is in the open state, and the changeover switch 10 is in the "high" level.
Switch to b. Therefore, the output of the reproduction head _H2 is cut off by the on/off switches 9 and 13, and only the output of the reproduction head _H1 is supplied to the field mode signal processing circuit 11 via the switches 12 and 10 and reproduced on the display 5. Ru.

Although the above example shows the case where the output of the reproducing head _H2 is below the reference level, the same applies to the reproducing head _H1 , and only the states of the switches 12 and 13 are interchanged.

Next, Figure 3 shows the field mode signal processing circuit 1.
1 is a diagram showing a configuration example of No. 1; FIG.

In the figure, 25 is a switch circuit, 26 is an H/2 delay circuit for skew correction, and 27 is a mixing circuit. The switch 25 is switched for each field by the PG pulse from the head 8. 28 is a reproduced signal processing circuit which converts the signal passed through the mixing circuit 27 into a signal suitable for display on the monitor 5.

With this configuration, the field signals obtained from one reproduction head (H ₁ or H ₂ ) in two consecutive field periods are divided by H/2 from each other.
By shifting the signal and supplying it to the reproduction signal processing circuit 28, a reproduced image without skew distortion can be obtained.

Note that other known interpolation circuits that form interpolation signals may be used as the field mode signal processing circuit.

According to the above configuration, when the playback outputs of both playback heads are above the reference level, the outputs of both heads are sequentially switched for playback, and when the playback output of one is below the reference level, playback is performed using only the playback output of the other head. I can do it.

In this embodiment, envelope detection is performed as a method for determining whether the reproduced signal is good or bad, but it may also be configured to detect the reproduced output through a high-pass filter that extracts high-frequency components of the reproduced signal, for example. In this way, a frame signal can be formed from other field signals when the high frequency characteristics are degraded.

(Effects) As explained above, according to the present invention, the image signal of the first field recorded in the first recording area of the recording medium and the second field independent of the first recording area The image signal of the second field recorded in the recording area is different from the recording medium.
In a playback device that sequentially plays back data using two playback heads, the quality of the playback output from the two playback heads is detected, and the playback image is played back from one recording area by one playback head according to the detection result. Since the reproduced image signal for one frame is formed by replacing the signal with the reproduced image signal reproduced from the recording medium by the other reproduction head, deterioration of the reproduced screen can be prevented and the information once recorded can be This has the effect that it can be used effectively.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional example, FIG. 2 is a block diagram of an embodiment according to the present invention, and FIG. 3 is a diagram showing an example of the configuration of a signal processing circuit 11. H ₁ and H ₂ are playback heads, 1 and 2 are playback amplifiers, 3 and 10 are selector switches, 4, 4', and 11 are signal processing circuits, 5 is a display, 6 is a magnetic sheet drive motor, 7 is a magnetic sheet, 8 is a PG detection head, 9, 12, 13 are open/close switches, 14, 15 are envelope detection circuits, 16, 17 are comparators, 19, 20 are R-S flip-flops, 22, 23 are OR circuits, 24 is a display It is.

Claims (1)

[Claims] 1. An image signal of a first field recorded in a first recording area of a recording medium and an image signal recorded in a second recording area independent of the first recording area. In an image signal reproducing apparatus that obtains one frame's worth of reproduced image signal constituted by the reproduced image signals of two fields by sequentially reproducing the image signal of the second field from the recording medium, detection means for respectively detecting the quality of the reproduced image signals for two fields reproduced from each recording area; and according to the detection result of the detection means, the reproduced image signal reproduced from one recording area is transferred to the other recording area. 1. An image signal reproducing apparatus comprising: a frame reproduced image signal forming means for forming a reproduced image signal for one frame by replacing the image signal with a reproduced image signal reproduced from a frame.