JPH03283149A - Track feed control method - Google Patents

Abstract

PURPOSE:To speedily reproduce a frame image even by a field head by performing no ATF control when the head is moved from a track where the head is positioned under ATF control to an adjacent track. CONSTITUTION:The ATF control is not performed when the head is moved from the track where the head is positioned under the ATF control to the adjacent track. Namely, when images of frame recording are reproduced by the field head, track feeding for the reproduction of a 1st field is performed under the ATF control and its reproduction output is sent to a memory. Then when the head is moved to the adjacent track for the reproduction of a 2nd field, the ATF control is omitted and a reproduced image is outputted. Consequently, the images of the frame recording can be reproduced speedily by the field head.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a track advance control method, and more specifically to a track advance control method for reproducing frame recorded images by a field head.

[Prior Art] In a still video system, frame images are recorded as two field images on separate adjacent tracks, and when a frame recorded image is played back by a field head, two adjacent field images are recorded on separate adjacent tracks. The head was sent to each track in turn to read the signals. In order to position the head on each track, so-called ATF control is performed. ATF control positions the reproducing head so that the reproducing head output is maximized, and has the advantage that a stable high reproduction output can be obtained even if the head feeding mechanism has poor feeding accuracy to some extent.

FIG. 2 is an explanatory diagram of the ATF control operation, in which the horizontal axis shows the head feed position and the vertical axis shows the head output.

For example, consider a case where you want to move the head from one track to another. At this time, it is assumed that the head is first sent to position A near the target track (maximum output position). The output at position A is stored, and then the head is advanced by a minute amount, and the output is compared with the previously stored output. This operation is repeated in the order of A→BCD→E until the head output becomes smaller than the previous output, and the head output is reproduced at the position just before that. It takes at least one rotation of the disk (IV) to move the head minutely and obtain the head output, and it takes IV to read the recorded signal, so in the example shown in Figure 2, it takes 8 seconds to obtain the playback output. become.

Furthermore, as shown in Fig. 3, even if the head reaches the position where the output is maximum in the first head movement,
Due to the head movement of D, 6V will be applied.

[Problems to be Solved by the Invention] In such a head feeding and positioning mechanism, when attempting to reproduce a frame image using the field head,
ATF must be performed twice, and it takes a very long time to obtain a reproduced image.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a track advance control method that can quickly reproduce frame images even with a field head.

[Means for Solving the Problems] The track feed control method according to the present invention is characterized in that ATF control is not performed when moving the head to an adjacent track from a track in which the head has been positioned by ATF control. .

[Operation] Since the time required for ATF control is omitted once, the reproduced output can be obtained earlier.

Since the movement is limited to adjacent tracks, the head output will not drop to an insufficient level.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is an operational flowchart of an embodiment of the present invention. Track feed mechanisms that can feed the head steplessly use cams and lead screws, but the feed accuracy must be considered. FIG. 4 shows the tracking accuracy of a common cam feeding device. As shown in FIG. 4, the curve representing the track feed accuracy is continuous, and if the cam surface is smooth, the curve will be smooth.

In FIG. 4, P is the overall track accuracy and Q is the pitch between adjacent tracks. In this way, the pitch between adjacent tracks is considered to be sufficiently good compared to the overall track accuracy. Therefore, it seems that there is no problem even if ATF control is omitted when moving the head to an adjacent track.

However, no matter how good the accuracy of the pitch between adjacent tracks is, as long as it contains errors, if the head is moved repeatedly without ATF control, the errors will accumulate and the accuracy will deteriorate. In order to prevent errors from accumulating, it is necessary to cancel the previous errors immediately before feeding a track for which ATF control is omitted. This can be solved by limiting the problem to tracks adjacent to the track where the process was performed.

As shown in FIG. 1, in this embodiment, as shown in FIG.
Then, perform ATF control (s2) and transfer the playback output to the memory (s3). When moving the head to an adjacent track for playing the second field, the ATF
The control is omitted (s4), and the reproduced image is output (s5).

[Effects of the Invention] As can be easily understood from the above explanation, according to the present invention, a frame recorded image can be quickly reproduced by a field head.

[Brief explanation of the drawing]

FIG. 1 is a flowchart of an embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams of the operation of ATF control, and FIG. 4 is a diagram showing the tracking accuracy of a general feeding device using a cam.

Claims (1)

[Claims] ATF is used when moving the head from a track where the head has been positioned by ATF control to an adjacent track.
A track feed control method characterized in that no control is performed.