JPH0312068A - Information signal reproducing device - Google Patents

Abstract

PURPOSE:To contrive the accurate reproducing by outputting a prescribed voltage signal during a prescribed time after instructing the commencement of a reproducing operation and restoring afterward an information signal by using an FM demodulation signal. CONSTITUTION:When the reproducing operation is instructed to start by a control circuit 8, a magnetic head 3 reaches onto a target track, and a switch 26 is connected to the side of B so that a constant voltage 27 is outputted by an FM demodulator 5, and hence the standby state is effective for a prescribed time. Then, after a lapse of the prescribed time, the switch 26 is connected to the side of A by the circuit 8, and a regenerative signal from the head 3 is demodulated by the demodulator 5, and its output is supplied to the circuit 8 via a deemphasis circuit 10 and an A/D converter 11. A control code is detected from this signal by the circuit 8 to discriminate the recording state. By this method, after a DC potential fluctuation of a signal to be supplied from the demodulator 5 to the converter 11 is stabilized, the presence of the control code is decided, and hence the accurate reproducing can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an information signal reproducing device for reproducing information signals from a recording medium on which the information signals are recorded.

[Prior Art] Conventionally, there is an electronic still video system that records still image signals and audio signals on a magnetic disk and reproduces the still image signals and audio signals from the magnetic disk.

In the electronic still video system mentioned above, a still image signal or an audio signal is FM-modulated and recorded on each concentric recording track formed on a magnetic disk along with a code signal for determining the type of signal during playback. .

Regarding still image signals, there are two types of still image signals: a wideband still image signal and a narrowband still image signal.The still image signal is FM-modulated together with a code signal for identifying the type during playback and recorded on a magnetic disk. It is set to be recorded.

In addition, after applying 1-time axis compression processing to the audio signal, the time axis compression rate, the track number where the corresponding still image signal is recorded, the track number where the continuous audio signal is recorded, etc. are required during playback. The information is FM modulated and recorded on a magnetic disk along with a control code indicating various types of information.

[Problems to be Solved by the Invention] However, in the above-mentioned electronic still video system, wideband still image signals, narrowband still image signals, and audio signals are mixedly recorded on the magnetic disk. The signal reproduced from each recording track has a different band and center frequency of the FM modulation signal, and the reproduced signal is
When demodulated, the DC potential differs depending on whether the signal is a wideband still image signal, a narrowband still image signal, an audio signal, or an unrecorded signal.

Then, during playback, when the signal to be played back switches from a wideband still image signal to an audio signal, or from a narrowband still image signal to an audio signal, etc., fluctuations in the DC potential that occur during FM demodulation may occur within the playback circuit. Due to the capacitor installed for AC coupling, the DC potential changes with ripples, and when the audio signal is played back, the control code content is incorrectly detected, causing the audio signal playback to malfunction. I was afraid it would get lost.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an information signal reproducing device that can accurately reproduce information signals recorded on a recording medium.

[Means for Solving the Problems] An information signal reproducing apparatus of the present invention includes a reproducing means for reproducing a recorded signal from a recording medium, an instructing means for instructing the start of a reproducing operation, and an information signal reproducing apparatus for reproducing a signal by the instructing means. FM demodulation means outputs a predetermined voltage signal for a predetermined time after being instructed to start the operation, and after the predetermined time FM demodulates and outputs the signal reproduced by the reproducing means; After a predetermined period of time after the start is instructed, the FM'
4Ii means for restoring the information signal using the signal outputted from the means.

[Operation] According to the above configuration, since the information signal is restored using the FM demodulated signal reproduced from the recording medium after a predetermined period after the start of the reproduction operation is instructed, the erroneous information signal is restored. You will be able to prevent this from happening.

[Example] Hereinafter, the present invention will be explained using examples of the present invention.

FIG. 1 is a diagram showing a schematic configuration of a playback device in an electronic still video system as an embodiment of the present invention.

In 1A, l is a magnetic disk on which various signals are recorded, 2 is a motor for rotating the magnetic disk,
3 is a magnetic head; 4 is the magnetic head 3 connected to the magnetic disk 1;
5 is an FM demodulator that performs FM demodulation of the reproduced signal reproduced by the magnetic head 3; 6 processes the reproduced signal reproduced by the magnetic head 3 and outputs a still image signal. a still image signal reproduction processing circuit; 7 is a display device that displays a still image corresponding to the still image signal output from the still image signal reproduction processing circuit °6;
8 is a control circuit for controlling the operation of the reproducing apparatus shown in FIG. 1; 9 is a memory for storing the recording status of each track on the magnetic disk 1; a de-emphasis circuit that performs de-emphasis processing having characteristics opposite to those of the emphasis processing performed during recording; 11 is an A/D converter; 12 is an A/D converter 11;
13 is a D/A converter; 14 is a low-pass filter (LPF) for removing the clock frequency component in the signal output from the D/A converter 13; ), 15 is a noise reduction circuit that suppresses noise components in the signal output from the LPF 14, and 16 is an audio output device that generates audio corresponding to the audio signal output from the noise reduction circuit 15.

2 and 3 are flowcharts for explaining the operation of the playback device shown in FIG. 1, and the operation of the playback device shown in FIG. 1 will be explained below according to FIGS. 2 and 3. .

First, before starting the playback operation, it is necessary to detect whether a magnetic disk l is loaded in the playback device (S101 in FIG. 2).
), if the magnetic disk l is not loaded, it will be in a standby state until the magnetic disk l is loaded, and the magnetic disk l will be in a standby state until the magnetic disk l is loaded.
If it is loaded, the head moving mechanism 4 moves the magnetic head 3 onto the outermost track on the magnetic disk l (3102 in FIG. 2).

Then, it is determined whether or not the magnetic head 3 moved by the head moving mechanism 4 has reached the target recording track as described above. The magnetic head 3 is moved until the

When the magnetic head 3 reaches the target track, it enters a standby state for a predetermined period of time (S104 in FIG. 2).
, after a predetermined period of time has elapsed, in order to determine the recording status of the target track, the control circuit 8 connects the switch 26 to the A side in the figure, supplies a clock signal to the A/D converter 11, and outputs a clock signal to the magnetic head. The reproduced signal reproduced by 3 is FM demodulated by FM demodulator 5, and de-emphasis circuit
After de-emphasis processing is performed at the A/D converter 11, the signal is converted into a digital signal and sent to the control circuit 8.
is supplied to Furthermore, the reproduced signal reproduced by the magnetic herad 3 is transmitted to a broadband filter 22 and a narrowband filter 24.
The signals that have passed through the filters 22 and 24 are detected by the detection circuits 23 and 25, and then sent to the control circuit 8.
is supplied to

Then, the control circuit 8 detects whether or not a control code exists in the digital signal output from the A/D converter 11, and if the control code exists, an audio signal is recorded on the target track. If the control code is not present, it is determined that the still image signal is recorded or unrecorded. If it is determined that no audio signal is recorded on the target track, it is determined whether a broadband still image signal is recorded on the target track, depending on the level of the detection signal supplied from the detection circuit 23.25. It is determined whether a narrowband still image signal is recorded or nothing is recorded, and the determination result of the recording status of the target track is stored in the memory 9 in FIG. 1 (s tos in FIG. 2).

Next, it is determined whether or not the recording status has been determined for all tracks on the magnetic disk l.
06) If the determination for all tracks has not been completed, the process returns to step S102, the magnetic head 3 is moved to the inner adjacent track on the magnetic disk l, the recording status is determined, and the determination for all tracks is performed. When the determination is completed, the state waits for operation of various operation keys on the operation unit 17 shown in FIG.
In the F state, when the playback start key 19 is turned on, the playback processing routine for playing back the audio signal or still image signal starts (3109 in Figure 2), and when the playback stop key 20 is turned on, the playback operation is ended. (Figure 2 S
ll mouth).

Next, the operation of the reproduction processing routine will be explained.

When the playback processing routine starts, the control circuit 8 first performs the following steps.
Please connect the switch 26 to the B side in the figure.S201 in Figure 3
), the track designation key 18 of the operation unit 17 is used to determine whether or not a playback track is designated (3202 in FIG. 3).
, press playback start key 1 when no playback track is specified.
9 is turned on, the outermost track of the tracks on the magnetic disk 1 on which audio signals are recorded is designated as the designated track (S205 in FIG. 3).

Then, the specified track is set and the playback start key 1 is pressed.
If 9 is turned on, move the magnetic head 3 to the head moving mechanism 4.
It is determined whether the magnetic head 3 has reached the designated track or not, and the magnetic head 3 is moved until on-track (S207 in FIG. 3).
.

When the magnetic head 3 is on track on the designated track, the switch 26 is connected to the A side in the figure (see S in Figure 3).
208), the signal reproduced by the magnetic head 3 is FM
After being FM demodulated in the demodulator 5 and subjected to de-emphasis processing in the de-emphasis circuit 10, the A/
It is digitized by the D converter 11, the audio signal part is stored in the audio storage memory 12, and the control code part is supplied to the control circuit 8 (S209 in FIG. 3).
.

In addition, when the switch 26 is connected to the A side in the figure, it is F.
The output of the M demodulator 5 is supplied to the de-emphasis circuit lO, and when the switch 26 is connected to the B side in the figure, the F
The center frequency signal of the M-modulated audio signal is sent to the FM demodulator 5.
Therefore, the potential at the time of FM demodulation is maintained by the constant voltage source 27.

This means that when the magnetic head 3 is on a track on which a still image signal is recorded or on an unrecorded track, the DC potential output from the FM demodulator 5 is on the magnetic head 3 or on a track on which an audio signal is recorded. Since the DC potential is sometimes different from the DC potential output from the FM demodulator 5, the magnetic head 3 or the track on the magnetic disk l where a still image signal is recorded or an unrecorded track is transferred to a track where an audio signal is recorded. When moving, the difference in the DC potential of the output of the FM demodulator 5 increases the DC voltage of the audio signal input to the A/D converter 11 due to the AC coupling capacitor that exists between the input terminal of the A/D converter 11. In order to prevent the level from fluctuating, the digitized audio signal is stored in the audio storage memory 1.
2, the output signal of the FM demodulator 5 is not supplied to the de-emphasis circuit lO, and the signal at a predetermined potential output from the constant voltage source 27 is sent to the de-emphasis circuit lO.
By supplying the output of the FM demodulator 5 to the de-emphasis circuit 10 only when the digitized audio signal is stored in the audio storage memory 12,
It is possible to prevent the DC potential at the input of the /D converter 11 from fluctuating, to accurately A/D convert the audio signal, and to prevent errors in detecting the control code recorded together with the audio signal. It will be like that.

As described above, the digitized audio signal is stored in the audio storage memory 12, and it is determined whether the audio signal for one track has been stored in the audio storage memory 12 (S210) in FIG. When this is completed, the switch 26 is connected to the B side in the figure (3211 in Figure 3).

Then, in accordance with the detected control code, if there is a recording track on the magnetic disk l in which a still image signal corresponding to the audio signal stored in the audio storage memory 12 is recorded, the control circuit 8 records the recording track. The magnetic head 3 is moved onto the track, the signal recorded on the recording track is reproduced, and the reproduced signal reproduced by the magnetic head 3 is subjected to FM demodulation in the FM demodulator 5, and then the still image signal reproduction processing circuit In step 6, reproduction signal processing is performed to restore the still image signal, and the restored still image signal is supplied to a display device 7, which displays a still image corresponding to the supplied still image signal.

Also, while a still image is being displayed as described above,
The digital audio signal stored in the audio storage memory 12 is read out, and after the read digital audio signal is converted into an analog signal in the D/A converter 13, unnecessary lock frequency components are removed by the low-pass filter 14. Further, noise components are suppressed in the noise reduction circuit 15 and outputted by the audio output device 16.

Furthermore, when there is no recording track on the magnetic disk l on which the corresponding still image signal is recorded, only the audio signal is reproduced and output in the same manner as described above (S212 in Fig. 3).
~S 218).

Then, the playback of the audio signal recorded on the l track ends.1. , if there is a continuing audio recording track on the magnetic disk l, the process returns to step 5206 and the continuing audio recording track is played back, and if there is no continuing audio recording track on the magnetic disk l, the playback process is performed. The operation of the routine ends. (Fig. 3 5219
).

As explained above, in the reproducing apparatus shown in this embodiment, when detecting the recording status for all tracks on the magnetic disk, the magnetic head is on track on the recording track. The A/D converter 11 is kept in a standby state for a predetermined period of time, and after the fluctuation in the DC potential of the signal supplied from the FM demodulator to the A/D converter is stabilized, the signal supplied from the FM demodulator is digitalized. By determining whether or not an audio signal is recorded on a recording track by determining the presence or absence of a control code, it is possible to prevent misjudgment of a track on which an audio signal is recorded. can.

Also, when the audio signal on the magnetic disk is reproduced from the recording track, the signal output from the FM demodulator is supplied to the de-emphasis circuit only when the audio signal is stored in the audio storage memory. By configuring
It is possible to prevent the DC potential of the signal supplied from the FM demodulator to the de-emphasis circuit from fluctuating, and to prevent erroneous detection of audio signals and control codes.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide an information signal reproducing device that can accurately reproduce information signals recorded on a recording medium.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of a playback device in an electronic still video system as an embodiment of the present invention. 2 and 3 are flowcharts for explaining the operation of the reproducing apparatus shown in FIG. 1. 3...Magnetic head 4...Head moving mechanism 5-FM demodulator 8...Control circuit l.-A/D converter 2...Speech storage memory 7...Operation unit 6...・Switch 3... Constant voltage source

Claims (1)

[Scope of Claims] An apparatus for reproducing information signals recorded on a recording medium, comprising: reproducing means for reproducing the recorded signals from the recording medium; instruction means for instructing the start of a reproducing operation; An FM device that outputs a predetermined voltage signal for a predetermined time after the start of the reproducing operation is instructed by the instruction means, and after the predetermined time, performs FM demodulation on the signal reproduced by the reproducing means and outputs the FM signal.
The FM demodulating device is characterized by comprising: demodulating means; and information signal restoring means for restoring the information signal using the signal output from the FM demodulating means after a predetermined period after the start of the reproduction operation is instructed by the instructing means. An information signal reproducing device.