JPS63268161A - Recording presence of absence detector for magnetic disk - Google Patents

Abstract

PURPOSE:To exactly detect the presence or absence of a recording signal without necessitating a complicated and highly accurate circuit by using a special comparison reference at the time of executing said detection even track of a magnetic disk such as a floppy disk, etc. CONSTITUTION:A reproduced signal from a floppy disk 11 is supplied to a DC implementation circuit 15 through a reproducing amplifier 13 and an AC amplifier 14. An output from the circuit 15 is inputted to an A/D converter 18. The converter 18 converts the output from the circuit 15 into a digital value by using a reference voltage from a reference power supply circuit 19. The resulting conversion output is taken in by a system controller 20 to decide on the presence or absence of a recorded signal. For this operation, the controller 20 uses a reproduced output from a part of the disk 11 other than the disk's signal-recorded track extent or that at a time when the disk 11 is stationary as a comparison reference. In such a way, the detection can be executed exactly without a need for making the circuitry complicated and highly accurate.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a detection device for detecting whether or not a signal is recorded on a magnetic disk such as a floppy disk.

Background of the Invention - Floppy disks are used as signal storage media in various devices. For example, in a still video system, a still video camera captures an image of a subject on an image sensor.
By modulating this read signal and supplying it to the recording head, it is recorded as a frame image signal for each track on the floppy disk. Then, the recorded images on the floppy disk are read out by a still video player or the like, and reproduced on a monitor television or printed as a hard copy using a printer.

In this system, when reproducing a recorded signal on a floppy disk, the presence or absence of a signal recorded on each track is detected, and reproduction control is performed only on the track on which a signal has been recorded.

'As mentioned above, in the playback control of magnetic disks such as floppy disks, the presence or absence of signal recording is often detected, and a conventional device for this detection is shown in FIG.

The track position of a reproduction head 12 is controlled with respect to the floppy disk 11, and a read signal from the reproduction head 12 is amplified by a reproduction amplifier 13. This reproduction amplifier 13
In addition to being taken out to a demodulation and video signal processing circuit (not shown) to obtain a reproduced image, the output of It is input to the comparison circuit 17 and compared with the comparison reference voltage VREF in the comparison circuit 17 to determine whether or not a signal is recorded. Also, the comparison circuit 17
Instead, there is also a system that converts the output of the DC amplifier 16 into a digital signal using an A/D converter and compares it with comparison reference data using a system controller or the like.

Problems to be Solved by the Invention - Conventional detection devices have a problem that makes stable detection difficult. This will be explained in detail below.

In the conventional device, when the playback disk 12 is tracked in the radial direction of the floppy disk 11, the waveforms at various parts become as shown in FIG. The output of the AC amplifier 14 (
In a), since the frequency of the reproduced signal is high, it is not possible to increase the degree of amplification in consideration of the influence on other circuits, resulting in a low level signal.

Therefore, the output (b) of the DC conversion circuit 15 is a rectification of the low level input, and the difference between the level of the signal recorded track and the level of the signal unrecorded track becomes small.

If this signal is used as the comparison input of the comparator 17, the comparator 17
This makes it difficult to set comparison standards and requires high resolution. Moreover, there is a possibility that erroneous judgments may occur. Therefore, DC amplification is performed by the DC amplifier 16, and the output (C) is compared with a large difference in signal level between the recorded track and the non-recorded track.

However, when the output of the DC amplifier 16 is used as a detection signal for tracking servo, the signal is limited to an extent that does not saturate, and there are also variations in the amplification degree of the amplifier 16 and differences in the read signal from the floppy disk 11. The amplification degree of the amplifier 16 is limited due to the variation. For this reason, the DC potential and comparison reference potential of the amplifier 16 require a circuit configuration that reduces changes due to external conditions such as temperature and aging, and while using high-precision circuit elements such as resistors, the amplification level and This has the problem of requiring fine adjustments to the comparison standard level, resulting in a complex and expensive detection device. This problem also occurs when the output of the amplifier 16 is A/D converted and detected by a system controller or the like, and for example, it is necessary to make the circuit such as the reference voltage of the A/D converter highly accurate.

An object of the present invention is to provide a detection device that can perform reliable detection without making the detection circuit complicated and highly accurate.

Means and Effects for Solving Problems In order to achieve the above-mentioned object, the present invention provides an apparatus for detecting the presence or absence of signal recording for each track from the playback output of a magnetic disk such as a floppy disk. The system is configured to detect the presence or absence of signal recording for each track using the portion of the disc that is outside the signal recording track range or the playback output when the disc is stationary as a comparison standard, and compares fluctuations in signal level due to variations in circuits and floppy disks. Compensate for standard fluctuations.

One Embodiment - FIG. 1 is a block diagram showing one embodiment of the present invention, in which a playback signal from a floppy disk 11 is converted into a DC signal, showing a case where a signal recording track is detected by A/D converting a detection signal. The part obtained by the circuit 15 is the same as the conventional one, and the output of the DC converting circuit 15 is used as the conversion input of the A/D converter 18. A/D converter 18 converts reference voltage to reference power supply circuit 19
The output of the DC conversion circuit 15 is converted into a digital value using this voltage as a reference. The converted output of the A/D converter 18 is received by the system controller 20 and a determination is made as to whether or not the signal should be recorded.

The system controller 20 determines the presence or absence of signal recording according to the control flow shown in FIG. The system controller 20 detects the setting of the floppy disk 11 (
In step S1), the playback head 12 is controlled to move to the position of track number 0 on the floppy disk (step S2). Here, track number O of the floppy disk 11 is an unrecorded portion outside the signal recording track range. In this state, the system controller 20ii takes in the conversion output of the A/D converter 18, and stores the signal Vs obtained by adding the margin VC to this signal VO as a comparison reference signal (step 53).Next, the system controller 20 inputs the track number N is set to 0 (step S4), the track number N is set to N+1 (step S5), and the track number N is set to N+1 (step S5).
This signal VN is compared in magnitude with the comparison reference signal VS (step S7).
. In this comparison, if VN>Vs, it is determined that the track with the track number N has been recorded (step S8). Further, if VN≦VS, the track with the track number N is determined to be unrecorded (step S9). After this, it is determined whether the track number N is the final track or not (step 5IO).
If it is not the last track, the process returns to step S5 and restarts the determination of the presence or absence of signal recording for the next track.

Therefore, in determining whether a signal has been recorded on each track of the floppy disk, the comparison standard VS is determined from the reproduction signal level of the unrecorded track of the floppy disk. This comparison reference voltage VS is designed to compensate for variations in the floppy disk 11, variations in the amplification level from the reproduction head 12 to the DC conversion circuit 15, variations in the reference voltage of the A/D converter 18, and temperature variations in each part. This changes along with the reproduced signal of the track, and the determination compensates for these variations and fluctuations. Along with this compensation, the degree of amplification of the reproduced signal necessary for determination can be reduced, making the conventional DC amplifier 16 unnecessary, and reducing the accuracy of the circuit elements constituting each part, including the conversion accuracy of the A/D converter. Eliminate the need for high-precision devices.

In addition, in the embodiment, the comparison of detection signals is not limited to the determination by the system controller using A/D conversion, but the same effect can be obtained by using a configuration in which analog signals are determined by a comparator. In addition, in order to obtain a signal outside the signal recording track range, it is also possible to use a reproduced signal from a portion outside the last track of the floppy disk. By reconfirming the judgment, the judgment can be made even more certain. Furthermore, a similar effect can be obtained by using a configuration in which the comparison reference signal VS is obtained when the Florapeela disk is at rest. Furthermore, when there is little variation in the floppy disk and the reproducing head, it is also possible to obtain a comparison reference signal VS by grounding the input of the reproducing amplifier 13. In this case, control for moving the reproducing head out of the range of the signal recording track becomes unnecessary.

Effects of the Invention As described above, the present invention is configured to detect the presence or absence of signal recording for each track using the playback output of the portion outside the signal recording track range of the magnetic disk as a comparison standard, so that the detection circuit This has the effect of ensuring detection while reducing the requirements for each part and simplifying its configuration.

[Brief explanation of the drawing]

' Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a control flowchart of the system controller in Fig. 1, Fig. 3 is a conventional block diagram, and Fig. 4 is a conventional waveform diagram of each part. . 11... Floppy disk, 12... Playback head, 13... Playback amplifier, 14... AC amplifier, 15
...DC converter circuit, 18...A/D converter, 20...
・System controller.

Claims (1)

[Claims] 1) In a device for detecting the presence or absence of signal recording for each track based on the playback output of a magnetic disk such as a floppy disk, a portion of the magnetic disk that is outside the signal recording track range or a stationary portion of the magnetic disk 1. A recording presence/absence detection device for a magnetic disk, characterized in that the presence/absence of signal recording for each track is detected using the reproduction output at a time as a comparison standard.