JPH0423271A - Recording state detector for track of magnetic disk - Google Patents

Abstract

PURPOSE:To accurately detect the recording state of a track in spite of the position of the track by comparing a signal to be decided outputted by reproducing the track with a prescribed reference value, and deciding whether or not the track is already recorded. CONSTITUTION:A track position detecting means 1 detects the track position of a magnetic disk D, and a reference value setting means 2 sets a small reference value, smaller toward the further inner peripheral side of the magnetic disk D the position of the track is located at. Also, an output means 3 for signal to be decided outputs the signal to be decided by reproducing the track, and a decision means 4 decides whether or not the track is already recorded by comparing the signal to be decided with the reference value. By employing such constitution, it is possible to accurately detect the recording state of the track in spite of the track position, and to prevent the presence/absence of records on the tracks at the inner and outer peripheral sides of the magnetic disk D from being judged erroneously.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for detecting the recording state of a track in a magnetic disk used, for example, in an electronic still camera.

[Conventional technology]

Electronic still cameras use magnetic disks as recording media. A magnetic disk usually has 5 recordable tracks.
There are 0 tracks, and images and the like are recorded on empty tracks, and cannot be recorded over previously recorded tracks. Therefore, when newly recording on a magnetic disk, an empty track is detected in advance, and a video or the like is recorded on the empty track. Such a detection operation of the recording state of a track is performed by performing envelope detection on a signal obtained by reproducing a track, and determining whether the voltage level thereof is larger than a reference value.

Since the relative speed between the magnetic disk and the magnetic head becomes slower on the inner circumference side of the magnetic disk, the wavelength of the signal recorded on the track becomes shorter on the inner circumference side of the magnetic disk. Therefore, even if the conditions such as the recording current supplied to the magnetic head are the same, the voltage value of the reproduced signal becomes smaller on the inner circumferential side of the magnetic disk, that is, the voltage value of the envelope detection output becomes smaller. To explain this with reference to Fig. 6, the envelope detection output (solid line Ll) on the recorded track increases as the track number increases.
In other words, the inner circumferential side of the magnetic disk becomes smaller, and similarly, the envelope detection output (
The dotted line L2) also becomes smaller on the inner peripheral side of the magnetic disk. Therefore, conventionally, the reference value (-Fish 1JsL3) is set to a constant value having a size intermediate between the maximum value of the envelope detection output of the unrecorded track and the envelope detection output of the recorded track.

[Problem to be solved by the invention]

However, when the envelope detection output increases due to noise in the reproduced signal, the envelope detection output (
The dotted line L5) becomes larger than the reference value (-point $j[L6), and as a result, an unrecorded track is erroneously recognized as a recorded track. If the reference value is set large to prevent such errors, the symbol Q in FIG.
As shown in , on the inner circumferential side of the magnetic disk, the envelope detection output (solid line L4) of the recorded track becomes smaller than the reference value (-dotted chain line L6), and the recorded track is mistakenly recognized as an unrecorded track. It ends up.

Conventionally, it has been difficult to set a reference value for determining whether or not a track has been recorded, and as a result, it has been erroneous to determine whether or not there is recording on the inner and outer tracks of the magnetic disk. There was a risk that the disk device would malfunction.

The present invention was made in order to solve such conventional problems, and an object of the present invention is to provide a device that can accurately detect the recording state of a track regardless of the track position of a magnetic disk. It is said that

[Means for Solving the Problem] As shown in the block diagram of the invention in FIG. 1, the magnetic disk track recorded state detection device according to the present invention includes means 1 for detecting the position of the track on the magnetic disk D; , means 2 for setting a smaller reference value as the position of the track is closer to the inner circumference of the magnetic disk D; means 3 for reproducing the track and outputting the determined signal; and means 3 for outputting the determined signal and the reference value. The present invention is characterized by comprising means 4 for determining whether or not the track has been recorded by comparison.

〔Example〕

The present invention will be explained below with reference to illustrated embodiments.

FIG. 2 shows a control circuit built into an electronic still camera to which an embodiment of the present invention is applied. The system control circuit 11 is a conventionally known microcomputer that controls the entire camera. An image of the subject is formed on an image sensor 13 by a lens 12 . The image sensor 13 is connected to a video processing circuit 15 via an imaging circuit 14, and the video formed on the image sensor 13 is transmitted to the imaging circuit 14.
The signal is input to the video processing circuit 15 via. In this video processing circuit 15, the video signal input from the imaging circuit 14 is divided into a color difference signal and a luminance signal, and the two color difference signals (R-Y, B-Y) are separated every IH (horizontal scanning period). arranged alternately. The video processing circuit 15 is connected to a video output terminal, and the video can be viewed by connecting a playback device (not shown) to this video output terminal.

In the disk drive, the magnetic hend 21 is configured to be displaced in the radial direction of the magnetic disk D by a tracking motor 22.

This motor 22 is driven and controlled by a tracking motor drive circuit 23. The magnetic disk D is rotationally driven by a spindle motor 24, and this motor 24 is driven and controlled by a spindle motor drive circuit 25. The PC coil 26 is provided to detect the rotational angular position of the magnetic disk D, and is connected to a spindle servo circuit 27 that controls the spindle motor drive circuit 25. Further, a frequency generator 28 provided in the spindle motor 24 is also connected to the spindle servo circuit 27. The trunking motor drive circuit 23 and the spindle servo circuit 27 are connected to and controlled by the system controller 11.

The luminance signal and two color difference signals of the video signal are each FM modulated and multiplex recorded on the same recording track.

Therefore, the video processing circuit 15 includes an FM modulation circuit 31 and an F.
An M demodulation circuit 32 is connected thereto. The FM modulation circuit 31 is connected to the magnetic head 21 of the disk device via a recording amplifier 33 and a switch 34. The FM demodulation circuit 32 connects the magnetic head 2 via a reproduction amplifier 35 and a switch 34.
Connected to 1.

The switch 34 is controlled by the system controller 11 and is configured to be selectively switched between the FM modulation circuit 31 side and the FM demodulation circuit 32 side. That is, when recording video data on the magnetic disk D, the switch 34 connects the FM modulation circuit 31 and the recording amplifier 33 to the magnetic head 21, whereby the video signal is FM modulated and recorded on the magnetic disk D. On the other hand, when reproducing the video signal stored on the magnetic disk D, the switch 34
connects the FM demodulation circuit 32 and the reproducing amplifier 35 to the magnetic head 21. Thereby, the video signal is FM demodulated and input to the video signal processing circuit 15, subjected to predetermined processing, and output to the video output terminal side.

An envelope detection circuit 41 is connected between the FM demodulation circuit 32 and the reproduction amplifier 35. Envelope detection circuit 4
1 is provided for envelope detection of the reproduced signal,
The envelope-detected output signal is sent to the A/D converter 42.
A/D converted by the system control circuit 1
1 is input.

FIG. 3 shows a magnetic disk D. This magnetic disk D is a 2-inch type and has 52 tracks. The 1st to 50th tracks from the outside are recording tracks for recording video, etc., the 51st track has nothing recorded on it, and the 52nd track is a cue track for recording so-called cue signals. It is. Among the recording tracks, the outermost one, that is, the recording track DI with track number "1" is 2On+m from the center of the magnetic disk.
The innermost recording track D2, that is, the recording track D2 with track number "50" is located 15.1 mm from the center of the magnetic disk. Therefore, as described above, the relative speed between the magnetic disk D and the magnetic head 21 differs greatly between the outer circumferential side and the inner circumferential side of the magnetic disk D, and therefore, the envelope detection output of the reproduced signal differs greatly depending on the track position. come.

This will be explained using FIGS. 4(a) to 4(e).

Each track on the magnetic disk has a vertical synchronization signal (VSyn
c) is recorded, so that one pulse signal P is output for one rotation of the disk.

That is, the interval between two pulse signals P corresponds to one track of video signals. As shown in FIGS. 4(b) and 4(c), the reproduced signal from the tracks on the outer circumferential side of the magnetic disk has a large amplitude, and therefore the envelope detection output is also large. On the other hand, as shown in FIGS. 4(d) and (e), the amplitude of the reproduction signal of the inner track is small, and the envelope detection output is small.

In response to such a difference in the envelope detection output with respect to the track position, in this embodiment, the reference value for determining whether or not a track is recorded is changed depending on the track position. FIG. 5 shows reference values (voltage values) for track numbers, ie, track positions, in this embodiment. The envelope detection output (solid line M1) on the recorded track becomes smaller toward the inner circumference of the magnetic disk, and the envelope detection output (dotted line M2) on the unrecorded track also becomes smaller toward the inner circumference. Therefore, the reference value (-dotted chain line M3) is set to be as small as possible on the inner circumferential side of the magnetic disk so that it is always between the envelope detection outputs of the recorded track and the unrecorded track, regardless of the track position. This standard value is: Standard value = 2-3 x track number / 100 (1)
is set by the formula. The unit of this standard value is ■
It is.

In other words, the reference value in this embodiment is determined to decrease linearly by 1 as the distance from the center of the magnetic disk of the track decreases, but it is not limited to this, and may be changed as necessary. It may be set to change in a curved line shape or a polygonal line shape.

As described above, in this embodiment, the reference value is always set between the envelope detection outputs of the recorded track and the unrecorded track. Therefore, Figures 6 and 7
Unlike the prior art described above with reference to the figures, the reference value never becomes smaller than the envelope detection output of an unrecorded track or larger than the envelope detection output of a recorded track. Therefore, even if the difference in the output of the reproduced signal between the inner and outer tracks of the magnetic disk is large, there is no error in determining whether or not a track is recorded.

FIGS. 8 and 9 are flowcharts of a program that sets the reference value (-dotted chain line M3) shown in FIG. 5 to determine whether or not a track is recorded, that is, a program that searches for an empty track.

In step 101, a value obtained by adding 1 to the track number of the currently reproduced track is determined as a new trunk number. In step 102, it is determined whether the new trunk number has reached "51", that is, whether the detection of empty tracks has already been completed up to the innermost track. Here, if the new track number has reached "51", this program ends; however, if the new track number has not reached "51", step 103~
Execute step 107 to obtain the envelope detection output and reference voltage S.
(standard value).

First, in step 103, the magnetic head is moved to a track with a new track number, and in step 104, reproduction processing of this track is started. In step 105, the envelope detection output E of the reproduced signal is A/D converted. In step 106, the reference voltage S is determined by calculation according to the reference voltage setting program shown in FIG. Next, in step 107, it is determined whether the envelope detection output E obtained in step 105 is greater than or equal to the reference voltage S.

If the envelope detection output E is equal to or higher than the reference voltage S, this track is a recorded trunk, so the process returns to step 101, and steps 101 to 107 are executed again to determine the recording state of the next track. On the other hand,
If it is determined in step 107 that the envelope detection output E is smaller than the reference voltage S, this track is an unrecorded track, so the process proceeds to step 108, where the disk device is switched from the play mode to the record mode. As a result, the electronic still camera can record images, etc. on this empty track.

In the reference voltage setting program, steps 111-1
14, the reference voltage S (reference value) is calculated according to equation (1) above.
Set. In step 111, the track number of the currently reproduced track is multiplied by three, and in step 112, the product obtained in step 111 is divided by 100. Then, in step 113, the quotient obtained in step 113 is subtracted from 2, and this result is set as the reference voltage S in step 114.

Note that the arithmetic expression (1) for determining the reference voltage is merely an example, and it goes without saying that it can be determined appropriately depending on the magnitude of the envelope detection output of the recorded track and the unrecorded track.

[Effects of the Invention] As described above, according to the present invention, the recording state of a track can be accurately detected regardless of the track position, and recording can be performed on the inner and outer tracks of the magnetic disk. This prevents erroneous determination of the presence or absence of

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention; FIG. 2 is a diagram showing a control circuit of an electronic still camera using an embodiment of the present invention; FIG. 3 is a plan view showing a magnetic disk; (a) is a diagram showing the vertical synchronization signal, Figure 4 (b) is a diagram showing the reproduced signal of the outer track, and Figure 4 (C) is a diagram showing the envelope detection output of the reproduced signal of the outer track. , FIG. 4(d) is a diagram showing the reproduced signal of the trunk on the inner circumferential side, FIG. 4(e) is a diagram showing the envelope detection output of the reproduced signal of the trunk on the inner circumferential side, and FIG. FIG. 6 and FIG. 7 are diagrams showing a conventional reference value and envelope detection output, FIG. 8 is a flowchart of an empty track detection program, and FIG. 9 is a diagram showing a reference value and envelope detection output in one embodiment. 3 is a flowchart of a reference voltage calculation program. D...Magnetic disk

Claims (2)

[Claims] (1) means for detecting the position of a track on a magnetic disk; means for setting a smaller reference value as the position of the track is closer to the inner circumference of the magnetic disk; and means for reproducing the track and outputting a signal to be determined. An apparatus for detecting a recorded state of a track of a magnetic disk, comprising: means for determining whether or not the track has been recorded by comparing the determined signal with a reference value. (2) The recording state detection device according to claim 1, wherein the reference value decreases linearly as the distance of the track from the center of the magnetic disk decreases.