JP2926907B2 - Information signal reproduction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A Industrial application field B Outline of the invention C Conventional technology D Problem to be solved by the invention E Means for solving the problem F Function G Example H Effect of the invention A Industrial application field The frequency modulation information signal obtained by frequency-modulating the carrier signal of the carrier signal is read from a recording medium on which a recording track formed of an array of a large number of pits, bumps or divided areas is recorded. The present invention relates to an information signal reproducing apparatus that obtains a reproduced information signal by applying a predetermined process to a read frequency modulated information signal.

B. Summary of the Invention According to the present invention, a frequency-modulated information signal obtained by frequency-modulating a carrier signal of a predetermined frequency by an information signal is recorded by forming a recording track composed of an array of a large number of pits, bumps or divided areas. An information signal reproducing apparatus that reads a frequency modulation information signal from a recording medium obtained to obtain a read frequency modulation information signal and obtains a reproduction information signal based on the obtained read frequency modulation information signal; The demodulated output signal obtained cancels the baseband component included in the read frequency modulation information signal, and the demodulated information signal obtained by demodulating the read frequency modulation information signal in which the baseband component has been canceled is subjected to reproduction processing and reproduced. By obtaining the information signal, it is caused by the baseband component included in the read frequency modulation information signal. It is obtained by allowing suppress an adverse effect such as to unwanted signal components or reproduction information signal included in the reproduced information signal.

C Prior Art As a color television system capable of obtaining a higher quality reproduced image as compared with a reproduced image obtained by a current NTSC system or other color television system, it is called a high definition television system. Television broadcasting based on such a high-definition television system has been put to practical use as a method for compressing an extremely wideband television signal into a predetermined bandwidth and transmitting the signal using a broadcasting satellite. I have.

A television signal based on such a high-definition television system, that is, a high-definition television signal (HDTV signal)
For example, the field frequency is 60 Hz, the frame frequency is 30 Hz, and the number of line periods in one frame period is 1125.
Further, the luminance signal frequency band is 20 MHz, and the color signal frequency band is 6 MHz.

For such an HDTV signal, recording on a recording medium and reproduction from the recording medium on which the recording has been performed are considered. In such a case, the HDTV signal is, for example, The luminance signal is sampled twice for each line period, divided into two-channel video signals, recorded on a recording medium, and reproduced from the recording medium. As the recording medium, a magnetic tape, a magnetic disk, an optical disk, or the like is used. For example, when an optical disk is selected as the recording medium, the line period components Y1, Y2 as shown in FIG. ,
, Y8,... Are sequentially continued, and a luminance signal Y having a frequency band of 20 MHz and FIG.
, The line period component P _B1 of the blue color difference signal,
P _B3 , P _B5 , P _B7 ,... And the line period components P _R2 , P _R4 , P _R6 , P _R8 ,. 6MHz frequency band
An HDTV signal composed of a color signal C is sampled so that line period components Y1, Y3, Y5, Y7,... Are extracted from the luminance signal Y, and the extracted line period components are extracted. The time axis for each is 5/3
For the color signal C, the line period component P _B1 of the blue color difference signal, the line period component P _{R2 of} the red color difference signal, the line period component P _B5 of the blue color difference signal, and the red The sampling of the line period components P _R6 ,... Is performed, and the time axis of each of the extracted line period components is reduced by half to increase the time axis by 1/2. 4C obtained by time-divisionally arranging the line period component of the luminance signal Y and the line period component of the blue color difference signal and the line period component of the red color difference signal subjected to time axis compression. As described above, for the divided video signal of the first channel (Ch-1) having a frequency band of 12 MHz and the luminance signal Y, sampling for extracting line period components Y2, Y4, Y6, Y8,. When done Moni, withdrawn the for each of the line period component which time the time axis extension axis and 5/3 times performed, also for the color signal C, the blue color difference signal line period component P _B3 and a red color difference signal The line period component P _R4 , the line period component P _B7 of the blue color difference signal and the line period component P _R8 of the red color difference signal are sampled, and sampling is performed for each of the extracted line period components. The time axis compression is performed by halving the time axis, the line period component of the luminance signal Y subjected to the time axis expansion, the line period component of the blue color difference signal subjected to the time axis compression, and the line of the red color difference signal. A second channel (C) having a frequency band of 12 MHz, as shown in FIG.
h-2).

That is, an HDTV signal composed of a luminance signal Y having a frequency band of 20 MHz and a chrominance signal C having a frequency band of 6 MHz has a vertical sampling frequency of 1 / 2F for the luminance signal Y.
v _L (Fv _L is the vertical sampling frequency of the line period), and two samplings having opposite phases are performed to form divided video signals of the first and second channels having a frequency band of 12 MHz. It is.

Then, a carrier signal of a predetermined frequency is frequency-modulated by each of the divided video signals of the first and second channels to form a frequency-modulated video signal of the first channel and a frequency-modulated video signal of the second channel. The frequency-modulated video signals of the first and second channels are recorded on the optical disk by separately forming recording tracks each having an array of a large number of pits according to the respective frequency modulation states.

Also, in this manner, the HDTV signal is a frequency-modulated video signal of the first and second channels, each of which is recorded on an optical disk having a recording track composed of an array of a large number of pits according to the frequency modulation state. Alternatively, the frequency-modulated video signals of the first and second channels are read from the optical disc duplicated based on the arrangement of a large number of pits forming each recording track, and are frequency-modulated respectively. . Then, the two-channel frequency demodulation output signals are respectively subjected to predetermined reproduction processing and combined to reproduce the HDTV signal.

D Problems to be Solved by the Invention A frequency modulation information signal such as a frequency modulation video signal of the first and second channels based on the HDTV signal described above,
A recording track formed of an array of a large number of pits according to the frequency modulation state is formed and recorded on an optical disk, and a recording track formed of an array of a large number of pits corresponding to a frequency modulation information signal. When the frequency modulation information signal is read from the optical disk recorded with the optical disk or the optical disk duplicated based on the optical disk based on the array of many pits forming the recording track, the optical disk A frequency modulation information signal as a recording signal, which is recorded by forming an array of recording tracks, and a frequency modulation information signal as a reading signal, which is read from an optical disk based on an array of a large number of pits forming a recording track. There is a problem that a difference in pulse signal duty ratio occurs between the two.

For example, when a frequency-modulated information signal having a pulse signal duty ratio as shown in FIG. 5A is used as a recording signal, the optical disk is provided with a high-level portion of the frequency-modulated information signal in accordance with the high-level portion. The arrangement of pits as shown in FIG. 5B is formed, and the frequency modulation information signal is recorded even with a recording track having an arrangement of a large number of pits. At this time, the pits are formed on the optical disk by injecting a light beam intensity-modulated by the frequency modulation information signal, which is a recording signal, into the optical disk. Due to the size of the spot to be formed, the length of each pit is slightly longer before and after the corresponding high-level portion of the frequency modulation information signal. When reading signals from the optical disc, the pits are arranged in accordance with the arrangement of pits as shown in FIG. 5B, for example, each pit has a high-level portion as shown in FIG. 5C. A frequency-modulated information signal having a pulse signal duty ratio is obtained as a read signal. Accordingly, each high-level portion of the frequency-modulated information signal obtained as a read signal is longer before and after the high-level portion of the frequency-modulated information signal corresponding to the recorded signal, and is obtained as a read signal. The pulse signal duty ratio of the frequency-modulated information signal to be obtained differs from the pulse signal duty ratio of the frequency-modulated information signal used as the recording signal. Such a phenomenon is hereinafter referred to as “asymmetry”.

Due to such asymmetry, the pulse signal duty ratio of the frequency modulation information signal obtained as a read signal,
As shown in FIG. 5C, the change in the frequency modulation information signal, which is a recording signal, with respect to the pulse signal duty ratio is such that each high-level portion of the frequency modulation information signal obtained as a read signal has Means that a pulse signal having a predetermined width τ before and after the high-level portion of the information signal is added and obtained,
Therefore, the frequency modulation information signal obtained as a read signal is assumed to include a baseband component.

For example, considering a component having a specific frequency fs in an information signal such as the above-described divided video signals of the first and second channels, the frequency-modulated information signal to be a recording signal is shown in FIG. 6A (horizontal axis: Frequency f, vertical axis: level L)
, A carrier component Po having a frequency fc, and a lower primary sideband component having a frequency fc-fs
P _-1 with respect to what is intended to include the frequency fc + high band side primary sideband component having fs P _+1, the frequency modulated information signal obtained as a read signal, Figure 6 B (horizontal axis: frequency f , Vertical axis: level L), a carrier component Po having a frequency fc, a lower primary sideband component P ₋₁ having a frequency fc−fs, and a higher primary sideband component having a frequency fc + fs. It includes a baseband component Pm having a frequency fs in addition to P _{+ 1} .

When the frequency-modulated information signal obtained as a read signal including a baseband component by asymmetry is frequency-demodulated, for example, FIG. 6C (horizontal axis: frequency f, vertical) An unnecessary signal having a frequency equal to the difference between the carrier frequency and the information signal frequency as shown as a signal Sm having a different frequency fc-fs from the information signal S having the frequency fs at the axis L is included. Therefore, the reproduction information signal obtained by performing the predetermined reproduction process on the demodulated output contains an unnecessary signal component. The unnecessary signal component included in the reproduction information signal in this way has an adverse effect on the reproduction information signal, for example, a DC level fluctuation, and, for example, when the reproduction information signal is a reproduction video signal, "Moire interference" occurs in the reproduced image based on the reproduced video signal.

Such a problem that the frequency modulation information signal obtained as a read signal by the asymmetry includes a baseband component is that the frequency modulation information signal as the read signal is recorded on a recording medium such as an optical disk as described above. Instead of the arrangement of a large number of pits, the same occurs when recording is performed with a recording track having an arrangement of a large number of bumps according to the frequency modulation state or an arrangement of a large number of divided areas.

In view of such a point, the present invention provides a frequency modulation information signal obtained by frequency-modulating a carrier signal of a predetermined frequency by an information signal to form a recording track composed of an array of a large number of pits, bumps or divided areas. Reading a frequency modulation information signal from a recorded recording medium to obtain a read frequency modulation information signal, and obtaining a reproduction information signal based on the obtained read frequency modulation information signal, a baseband component included in the read frequency modulation information signal It is an object of the present invention to provide an information signal reproducing apparatus capable of suppressing unnecessary signal components included in a reproduced information signal or adverse effects on the reproduced information signal due to the above.

E Means for Solving the Problems In order to achieve the above object, an information signal reproducing apparatus according to the present invention provides a frequency modulation information signal obtained by frequency-modulating a carrier signal of a predetermined frequency with an information signal. The read frequency modulation information signal obtained from the reading means is demodulated to the output side of the reading means for reading the frequency modulation information signal from a recording medium on which a recording track formed of an array of pits, bumps or divided areas is formed and recorded. A baseband component canceling means for canceling a baseband component included in the read frequency modulation information signal based on the obtained demodulated output signal is provided, and the read frequency modulation in which the baseband component is canceled by the baseband component canceling means. A demodulation means for demodulating the information signal to obtain a demodulated information signal; and performing a reproduction process on the demodulated information signal to obtain a reproduced information signal. Constructed arranged and a reproduction processing unit.

In the information signal reproducing apparatus according to the present invention configured as described above, the baseband component canceling means for canceling the baseband component included in the read frequency modulation information signal obtained from the reading means is provided, and the baseband component A reproduction information signal is obtained based on a demodulation information signal obtained by demodulating the read frequency modulation information signal from which the baseband component has been canceled by the cancellation means. Therefore, it is caused by the baseband component included in the frequency modulation information signal read from the recording medium. Unnecessary signal components included in the reproduction information signal or adverse effects on the reproduction information signal are effectively suppressed. For example, DC level fluctuation of the reproduction information signal caused by the unnecessary signal component included in the reproduction information signal, or In the case where the reproduced information signal is a reproduced video signal, "moire interference" on a reproduced image based on the reproduced video signal due to an unnecessary signal component included in the reproduced video signal is suppressed.

G Embodiment FIG. 1 shows an example of an information signal reproducing apparatus according to the present invention.

In this example, as shown in FIG. 4C, a first channel digital divided video signal Dv1 having a frequency band of 12 MHz obtained based on an HDTV signal has a first channel.
The digital audio signal Da1 of the first channel is added to form a digital information signal of the first channel, and a carrier signal having a predetermined frequency is converted into a frequency by the first channel information signal Sr1 obtained by converting it into an analog signal. Frequency modulated information signal SM formed by modulation
1 and a digital audio signal Da2 of the second channel to a digital divided video signal Dv2 of the second channel having a frequency band of 12 MHz, also obtained based on the HDTV signal, as shown in FIG. 4D. Is added to form a digital information signal of a second channel, and a carrier signal having a predetermined frequency is frequency-modulated by an information signal Sr2 of the second channel obtained by converting the digital information signal into an analog signal. The information signal SM2 is
An optical disk OD recorded with first and second recording tracks formed by an array of a large number of pits according to each frequency modulation state is mounted.

Then, the light beam from the optical reproducing head unit 40 is applied to the first recording track on the optical disc OD by the objective lens LF.
Through the objective lens LF, the light beam modulated by the first recording track returns to the optical reproducing head unit 40, and the optical reproducing head unit 40 converts the frequency modulation information from the first recording track on the optical disk OD. The signal SM1 is read, and a read frequency modulation information signal SM1 'is obtained. In addition, a light beam is made to enter the second recording track of the optical disk OD from the optical reproducing head unit 41 through the objective lens FL, and the light beam modulated by the second recording track is optically reproduced through the objective lens FL. Returning to the head section 41, the optical modulation head section 41 reads the frequency modulation information signal SM2 from the second recording track on the optical disk OD, and obtains the read frequency modulation information signal SM2 '.

The read frequency modulated information signal SM thus obtained
1 'and SM2' include frequency-modulated information signals SM1 and SM2, respectively, and further include a baseband component based on asymmetry, for example, a baseband component Pm shown in FIG. 6B.

The read frequency modulation information signal SM1 'obtained from the optical reproduction head section 40 and the read frequency modulation information signal SM2' obtained from the optical reproduction head section 41 are respectively a baseband component canceling section 42 and a baseband component canceling section 43. Supplied to The baseband component canceling portions 42 and 43 have the same configuration, and are formed, for example, as shown in FIG.

In the example of the baseband component canceling unit 42 or the baseband component canceling unit 43 shown in FIG.
Read frequency modulation information signal SM1 ′ or SM2 ′ from
The signal is supplied to a subtraction circuit 23 through a delay line (DL) 22 and to a frequency demodulation unit 24. In the frequency demodulation unit 24, the read frequency modulation information signal SM1 'or SM2' is demodulated, and the frequency modulation information signals SM1 and SM2 are demodulated.
A demodulated output signal SB1 'or SB2' including a baseband component based on 2 is obtained and supplied to the level control unit 25 and the synchronous detection unit 26. Such a demodulated output signal SB1 'or SB2' includes not only a baseband component based on the frequency modulation information signals SM1 and SM2, but also a read frequency modulation information signal such as an unnecessary signal Sm shown in FIG. 6C. SM
An unnecessary signal resulting from a baseband component by asymmetry included in 1 ′ and SM2 ′ is also included. The level of this unnecessary signal depends on the read frequency modulation information signals SM1 'and S1.
It is smaller than the level of the baseband component included in M2 '. The level control unit 25 outputs the demodulated output signal SB1 'or S
The level of B2 'is controlled in accordance with the detection output Sd of the synchronous detection unit 26, and the level-controlled demodulation output signal SB1' or SB2 '
Is supplied to the subtraction circuit 23. The delay time in DL22 is
A signal corresponding to a delay time of the level-controlled demodulated output signal SB1 'or SB2' obtained from the level control unit 25 with respect to the baseband component included in the read frequency modulation information signal SM1 'or SM2' from the input terminal 21. Is done.

In the subtraction circuit 23, the demodulated output signal SB1 'or SB2' whose level has been controlled by the level control unit 25 is subtracted from the read frequency modulation information signal SM1 'or SM2' through DL22, whereby the read frequency modulation information signal SM1 '
Alternatively, the baseband component included in the SM2 'by asymmetry is canceled by the baseband component included in the level-controlled demodulated output signal SB1' or SB2 '. At this time, the frequency modulation information signal in the read frequency modulation information signal SM1 'or SM2'
The level of SM1 or SM2 is reduced by the unnecessary signal included in the demodulated output signal SB1 ′ or SB2 ′, but the unnecessary signal included in the demodulated output signal SB1 ′ or SB2 ′ supplied to the subtraction circuit 23 is Is controlled by the level control unit 25 to have a relatively low level. Therefore, the demodulated output signal SB1 'or S1' of the frequency modulation information signal SM1 or SM2 in the subtraction circuit 23 is output.
The reduction of the level by the unnecessary signal included in B2 'does not substantially cause a problem. Then, at the output end of the subtraction circuit 23, the read frequency modulation information signal SM1 ″ or SM2 ″, which is assumed to include the frequency modulation information signal SM1 or SM2 whose baseband component is canceled and whose level is reduced, is obtained. It is led to an output terminal 27 and is a synchronous detector 26.
Supplied to

In the synchronous detector 26, synchronous detection is performed based on the demodulated output signal SB1 'or SB2' for the read frequency modulation information signal SM1 "or SM2" from the subtraction circuit 23, and the detection output Sd becomes the read frequency modulation information signal. SM1 ″ or SM
The detection output Sd is obtained as a detection output for the baseband component remaining in 2 ″. The demodulation output signal SB supplied to the subtraction circuit 23 in the level control unit 25 by the detection output Sd.
The level of 1 'or SB2' is controlled. At this time, the level of the baseband component included in the demodulation output signal SB1 'or SB2' is included such that the detection output Sd from the synchronous detection unit 26 becomes zero, and is included in the demodulation output signal SB1 'or SB2'. Unwanted signal level is read frequency modulated information signal SM
Control is performed so that the level of the frequency modulation information signal SM1 or SM2 included in 1 'or SM2' does not substantially cause a problem. That is, the synchronous detection unit 26 determines that the read frequency modulation information signal SM1 ″ or SM2 ″ obtained from the subtraction circuit 23 does not include a baseband component, and the frequency modulation information signal SM which has a level reduction that does not substantially cause a problem.
1 or SM2, and a read frequency modulation information signal SM1 ″ or SM2 ″ in which the baseband component included in the asymmetry is sufficiently canceled is obtained at the output terminal 27. become.

FIG. 3 shows another example of the baseband component canceling unit 42 or the baseband component canceling unit 43. In this example, parts corresponding to those in the example shown in FIG. Reference numerals are given. Then, in the example shown in FIG. 3, instead of the synchronous detection unit 26 in FIG.
The read frequency modulation information signal SM1 ″ obtained from the subtraction circuit 23
Alternatively, regarding a specific signal in the baseband component remaining in SM2 ″, for example, a sampling output obtained from a signal sampling circuit 28 for extracting a horizontal synchronization pulse of a video signal, a demodulated output signal SB1 ′ or SB2 obtained from a frequency demodulation unit 24. ′
A specific signal therein, for example, a synchronous detection unit 30 that performs synchronous detection based on a sampling output obtained from a signal extraction circuit 29 that extracts a horizontal synchronization pulse of a video signal, and further, a detection from the synchronization detection unit 30 Output Sd 'is a signal sampling circuit
For example, the signal is supplied to the level control unit 25 via a sample and hold circuit 31 which performs sampling at a timing synchronized with a horizontal synchronization pulse of a video signal.

In this example as well, the detection output Sd ′ from the synchronous detection unit 30 is set to zero, that is, the read frequency modulation information signal SM1 ″ or SM2 ″ obtained from the subtraction circuit 23 does not include a baseband component. The read frequency modulated information signal SM1 "or SM2" from which the baseband component included in the asymmetry is sufficiently canceled is obtained at the output terminal 27. The example shown in FIG. 3 is expected to improve the control accuracy as compared with the example shown in FIG.

As described above, the read frequency modulation information signal SM1 ″ obtained from the baseband component canceling unit 42 and in which the baseband component included in the asymmetry has been sufficiently canceled is demodulated in the frequency demodulating unit 44, whereby the frequency An information signal Sr1 of the first channel is obtained from the demodulation unit 44, and a read frequency modulation information signal SM2 ″ obtained from the baseband component canceling unit 43, in which the baseband component included in the asymmetry is sufficiently canceled, is obtained. Demodulation is performed by the demodulation unit 45, whereby the information signal Sr2 of the second channel is obtained from the frequency demodulation unit 45. The information signal Sr1 of the first channel from the frequency demodulation unit 44 is digitized by an analog / digital (A / D) conversion circuit 46, and is supplied to the frame buffer memory 47 as a digital information signal of the first channel. Then, in the frame buffer memory 47, one frame of the digital divided video signal Dv1 of the first channel in the digital information signal of the first channel is accumulated, and the digital divided video signal Dv1 of the first channel is stored. But 1
The video data is supplied from the frame buffer memory 47 to the video decoder 48 every frame formation. Similarly, the information signal Sr2 of the second channel from the frequency demodulation unit 45 is digitized by the A / D conversion circuit 49, and is converted into a digital information signal of the second channel.
And in the frame buffer memory 50,
One frame of the digital divided video signal Dv2 of the second channel in the digital information signal of the second channel is accumulated, and the digital divided video signal Dv2 of the second channel is converted into a frame every one frame. The data is supplied from the buffer memory 50 to the video decoder 48.

In the video decoder 48, based on the digital divided video signals Dv1 and Dv2 of the first and second channels, the digital divided video signal Dv1 of the first channel is output.
Are combined with the line period of the digital luminance signal Dy forming the digital divided video signal Dv2 of the second channel to reproduce the digital luminance signal Dy. The line period of the digital blue color difference signal D _PB forming the digital divided video signal Dv1 of the channel and the line period of the digital blue color difference signal D _PB forming the digital divided video signal Dv2 of the second channel are combined, and It reproduced color difference signals D _PB, a digital red color difference signal for forming a digital division video signal Dv2 line period and the second channel of the digital red color difference signal D _PR to form a digital division video signal Dv1 of the first channel The _DPR line period is combined to reproduce the digital red color difference signal _DPR .

The information signal Sr1 of the first channel obtained from the frequency demodulation unit 44 and the information signal Sr2 of the second channel obtained from the frequency demodulation unit 45 are respectively converted into audio data separation units 51
And 52, the audio data separation unit 51 obtains the digital audio signal Da1 of the first channel based on the information signal Sr1 of the first channel, and the audio data separation unit 52 A digital audio signal Da2 of the second channel is obtained based on the information signal Sr2 of the second channel. The first channel digital audio signal Da1 from the audio data separation unit 51 and the audio data separation unit 52
Second channel digital audio signal from
Each of Da2 is converted into a digital audio signal whose time base is expanded by the audio decoder 53, and is supplied to digital / analog (D / A) conversion circuits 54 and 55. Then, in the D / A conversion circuit 54, the digital audio signal Da1 of the first channel expanded on the time axis.
Is converted into an analog signal, and a reproduced audio signal A1 is obtained.
Also, in the D / A conversion circuit 55, the second
The digital audio signal Da2 of the channel is converted into an analog signal to obtain a reproduced audio signal A2, which is led to the first and second audio signal output terminals 56 and 57, respectively.

On the other hand, the digital luminance signal Dy obtained from the video decoder 48 is converted into a luminance signal Y by analogization in a D / A conversion circuit 63, and this luminance signal Y is derived to a first video signal output terminal 64 as a reproduced luminance signal. Is done. Further, the digital blue color difference signal D _PB reproduced by the video decoder 48 is converted into a blue color difference signal P _B by analogization in the D / A conversion circuit 65, and this blue color difference signal P _B is supplied to a second video signal output terminal. together is derived as reproduced blue color difference signals 66, the digital red color difference signal D _PR which has been reproduced by the video decoder 48, the analog data in the D / a conversion circuit 67 is the red color difference signals P _R, the red color difference signal P _R
Is output to the third video signal output terminal 68 as a reproduced red color difference signal.

As described above, the luminance signal Y as the reproduced luminance signal and the blue color difference signal P _B as the reproduced blue color difference signal are supplied to the first, second, and third video signal output terminals 64, 66, and 68, respectively. , and the red color difference signals P _R as playing a red color difference signal
Are reproduced based on demodulated outputs obtained by demodulating the read frequency modulation information signals SM1 ″ and SM2 ″ in which the baseband components included in the asymmetry have been sufficiently canceled by the baseband component canceling units 42 and 43. The frequency modulation information signal SM read from the optical disk OD.
In 1 ′ and SM2 ′, unnecessary signal components due to the baseband component included by asymmetry are assumed to be sufficiently suppressed, and therefore, the DC level is stabilized, and in the reproduced image based on them, "Moire interference" will be suppressed.

H Advantageous Effects of the Invention As is clear from the above description, according to the information signal reproducing apparatus of the present invention, the frequency modulation information signal obtained by frequency-modulating the carrier signal of the predetermined frequency by the information signal includes a large number of pits, A frequency modulation information signal is read from a recording medium on which a recording track formed of an array of bumps or divided areas is formed to obtain a read frequency modulation information signal, and a reproduction information signal is generated based on the obtained read frequency modulation information signal. In order to obtain the read frequency modulation information signal, the read frequency modulation information signal obtained from the recording medium is provided with a baseband component canceling means for canceling the baseband component included by asymmetry, whereby the baseband component is sufficiently canceled. Is obtained based on the demodulated information signal obtained by demodulating Due to a base band component included in the read frequency modulated information signal, so that the adverse effects such as to unwanted signal components or reproduction information signal included in the reproduced information signal is effectively suppressed. Therefore, the DC level fluctuation of the reproduction information signal caused by the unnecessary signal component included in the reproduction information signal, or the reproduction video signal due to the unnecessary signal component included in the reproduction video signal when the reproduction information signal is the reproduction video signal "Moire interference" or the like for a reproduced image based on the image can be suppressed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of an information signal reproducing apparatus according to the present invention, FIG. 2 is a block diagram showing an example of a specific configuration of a baseband component canceling unit in the example shown in FIG.
FIG. 3 is a block diagram showing another example of the specific configuration of the baseband component canceling unit in the example shown in FIG. 1, and FIG.
FIGS. 5A to 5D are waveform diagrams for explaining the recording process of the HDTV signal, and FIGS. 5A to 5C and 6A to 6C are a conceptual diagram and a characteristic diagram for explaining the asymmetry. In the figure, 23 is a subtraction circuit, 24, 44 and 45 are frequency demodulators, 25
Is a level control section, 26 and 30 are synchronous detection sections, 40 and 41 are optical reproducing head sections, 42 and 43 are baseband component canceling sections,
48 is a video decoder, and OD is an optical disk.

Claims (1)

(57) [Claims] 1. A recording medium on which a frequency-modulated information signal obtained by frequency-modulating a carrier signal of a predetermined frequency by an information signal is recorded by forming a recording track comprising an array of a large number of pits, bumps or divided areas. Reading means for reading the frequency modulation information signal; and a baseband component included in the reading frequency modulation information signal based on a demodulated output signal obtained by demodulating the read frequency modulation information signal obtained from the reading means. Baseband component canceling means for canceling, demodulating means for demodulating the read frequency modulation information signal on which the baseband component has been canceled by the baseband component canceling means to obtain a demodulated information signal, and reproducing the demodulated information signal. And a reproduction processing means for obtaining a reproduction information signal.