CA1082358A - Device for recording or reproducing a video signal - Google Patents
Device for recording or reproducing a video signalInfo
- Publication number
- CA1082358A CA1082358A CA263,903A CA263903A CA1082358A CA 1082358 A CA1082358 A CA 1082358A CA 263903 A CA263903 A CA 263903A CA 1082358 A CA1082358 A CA 1082358A
- Authority
- CA
- Canada
- Prior art keywords
- track
- diameter
- filter
- amplitude
- lowering
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/22—Signal processing not specific to the method of recording or reproducing; Circuits therefor for reducing distortions
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B3/00—Recording by mechanical cutting, deforming or pressing, e.g. of grooves or pits; Reproducing by mechanical sensing; Record carriers therefor
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/76—Television signal recording
- H04N5/91—Television signal processing therefor
- H04N5/93—Regeneration of the television signal or of selected parts thereof
- H04N5/931—Regeneration of the television signal or of selected parts thereof for restoring the level of the reproduced signal
- H04N5/9315—Regeneration of the television signal or of selected parts thereof for restoring the level of the reproduced signal the level control being frequency dependent
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Multimedia (AREA)
- Optical Recording Or Reproduction (AREA)
Abstract
Abstract of the Disclosure A device for recording or reproducing a video signal in the form of a frequency modulated carrier on the spiral track of a video disc comprising a transducer used for recording or reproduction whose output amplitude reduces as the recorded wavelength drops and a frequency selective filter for lowering the amplitude of the lower side band of the carrier to a larger extent as the diameter of the track decreases.
Description
~823S8 It i~ known to record a video ~i~nal, e.g. a televi~ion signal, along a s~iral track of a round recording carrier, a ~o-called video di~c. l~ecording and reproduction thu~ take place at a con~tant rotational speed for example 15~0 rpm during reproduction. At such a constant rotational speed the relative ~peed betw~en the disc and the recording or reproducing element i~ not constant. T~lis speed becomes smaller a~ the diameter of the track decrease~, thu~ towards the inside of the disc. The recorded waveleng$h tllU9 decreases towards the centre of the disc for ~ pre~etermined recording fre4uency. ~mis wffuld not be any disadva~tage in it~elf if the tran~ducers operated independently of the 15 respective wavelen~th. !~
In practi e howev`er the tran~ducer has a charucter-i~tic curve according to which its outpu~amplitude ~ :
- . ~ -decreases as the wavelength drops.~ When recording, this ~: : mean~ that the mechanical~mo~ement~amplitude for a cutting proce9s wlth a dropping waveleDgt~:is ~maller with a : :
con~bant eontrol voltage ~or the tran8ducer. It i~ al~o po~sible that, in:fact, the mecbanical de~leotion ampli-tude-re~in~ the same yet the amplitude of the ~ignal cut into the disc decrease3 as the wavelength drop~, becau~e there i~ a lack~of:sharpnes~ of the cutting ~tylu~
~uring repro~uction, the output amplitude of the electrical signal supplied by the, for example mechanical-electrical, tra~sducer drops accordingly a~ ~
~ ~, :
t~; ' ', ~ 8Z3SI!~
the wav~lengtll dro~
l~ecording of th~ vid~o si~nul takes place ~enerully in the rorm of a fre~uency mo~ulated carrier. As fairly large wavelengths, i.e. low frequencie~, have u higher output amplitude according to the ~tated curve of the tran~ducer than ~mall wavelengths, i.e. high fre~uencie~, then there is a rise in the lower side band of the fre~uency modulated carrier. 'l'hereLore it is nece~ury to lower the lower ~ide band of the frequency modulated carrier with a filter according to the characteristic curve. The upper ~id0 band will not be considered in greater detail below becau~e in genarnl only the lower side band is utilized duri~g reproduction and the uppar side band is omitted.
In practice, it has been proved that when there is this type o~ correction, given a large track diameter, i~e. at the outer edge of the video di~c where the a~erage wavelengths are large, the ~harpne~ o~ the image reproduced is poor and the ~ignal to noise ratio is relatively smallO On the other hand with a small track diameter, i~e. at the~inner edge of the di~c the sharpness is relatively good ~hil~`~h~ ~nter~erence ~pacing is ~all. ~ mus ~harpnes~and interference . . .
spacing are not constant o~er the entire length of the recording track.
The invention seeks to provide means by which the sharpne~s ~and signal to noise ratio may be made as independent as pos`sible of the respective track diameter 1t~8~358 90 that th~y r~main substuntially unch~ed during playing of a disc.
l~ccording to tl~e invention, there is provided a device for recording or re~roducing a video signal in the form of a frequency modulated carrier on a spiral ; 5 track of u video disc comprising a tr~nsduc~r used during recording or reproduction nnd having an output signul whose ~mplitude decreases as the re¢ordèd wave-length drops and a fre~uency selective filter for lowering the amplitude of the lower side band of the : carrier.to an increasing extent as the di~meter of the track decreases.
Further according:to the in~entlon, there i~
provided a device for recordin~ or reproducing a video signal along a spiral tr~ck of a video di~c in the ~orm of a ~requency modulated carrier, wherein the amplitude of the output signal of the transducer used durlng recording or reproductio~ decreases~:as the recorded wavelength drop~ ~nd a fre~uency selective filter is provld~d ~or lowering the amplitude 4f.~the lower side band - 20 ~ ~ of the carrier with rospect to the;carrier, characterized : ~ in-that't'he curve of the ~ilter i~ dependent o~ the re~pective diameter of the track ~uch tha~t the~lowering increa8e~ as the diameter of the track decreases.
~ .
A video dlsc~player~is known (German O~fen-legungsschrift No. 2,503,944) in which,~when there is spiral scanning, the change in the transmlssion function (dependence of the amplitude of the ~canned signal on the fre4uency3 is taken into account by means of a filter as , : ~
th~ ~iumet~r of tll~ truck ~ecr~u~es, s~ ilter lying in the prlt~l of tlle scanned fre~uency Ino~ulate~
curri~r. ~itll this circuit, however, the wllplitude o~ a ~)ilot sigrnal recorde~ at constant umplitude is evaluuted ,md the pass region of the filter i~
changed in dependence ther~on. ~irect control of the decrease in am~litude of the lower side b~nd of the scu~ned fre~uency modulated currier is not provided in depend~nce on the respective scanning radius. The filter does not cause any variable lowering in amplitude of the lower side band and the res~ective position of the scanner radially to the vldeo disc is ulso not directly evaluated. 'l'his ~rrangement does not deal with holding the shar~ness and interference spacing as constant as possible over the length o~
the track, is not dealt wlth here.
'~hu~ 7 the varying gradient of the stated curve of the transducer is taken into consideration witl large and small wavelengths, so that~ correction is matched in each case to the re~uireme~ts of a certain track diameterr 'l'he correction which takes place and is dependent on the radius, may be used basically when recording or reproducing or both simultaneously. ~orrection during recording ~ay also :
take the distortion brought about by the transducer curve during reproductio~ into consider~tion eith~r completely or partially. ~orrection during reproduction may also either completely or partially balance out .
~ .
~' ' . . ~ ' J 0l~il23SI~
distortion which has occurred as a resul-t of the t.ransducer curve during recording.
The invention is preferably used with so-called pressure scanning, as is described in our Canadian Patent No.
923,046 issued March 20, 1973 and our Canadian Patent No.
942,682 issued February 26, 1974. It is not however restricted to a certain recording method but may be used generally for a spiral recording having different relative speeds between the scanner and the disc. The lowering of the lower side band is generally less during recording than during reproduction.
The invention will now be described in greater detail by way of example with reference to the drawings in which:
Figure 1 shows a general circuit diagram of the arrangement;
Figure 2 shows characteristic curves of the scanner :
for the purpose of illustrating the mode of operation;
Figures 3 and 4 show embodiments for the filters . used; .
Figure 5 shows a group of curves for the decrease in accordance with the invention, which decrease is dependent on radius;
Figure 6 shows the dependence of the decrease on the radius of the video disc at a frequency of 1 MHz;
=:~
. . .
lilZ358 I~'igure 7 Silo~S a furtller group o~ curves ~or reproduction, and ~`igure 8 shows u curve for recording for the lowermost side band fre~luency of approximately 1 ~lz~
ln Fi6ure 1 a video disc having u drive dog is coupled to a shaft 3 of a drive motor 4. 'l'he video disc 1 rotates above a fixed support 5 on an air cushion 6. Sc~nning take~ place by : 10 means of a scanner 7 whioh i~ fixed to a carriage 8. 'l'he carriage 8 is pas~ed over the vldeo disc 1 in a radial direction by means of a drive 10 throu~h - a cord 9, according to the gradient of the spiral 4.' recording track~ '~he exact guidance of the scanner takes place by means of the mechanically cut groove and by means of d resilient mounting of the scanner 7 on`the carriage 8. lrhe signals are recorded mechanically on the Yideo disc~1 ln the : :~
form of a fre~uency modulated car~ler for scanning 20 ~ according to the pressure scanning prin~iple. 'l~e drive 10 is also controlled by the motor 4 as is indicated by the broken llne 11. T~le signal remo~ed by the scanner 7 in the form of a carrier 17 frequency modulated with the video signal is suppled ~ia a line "~
12 to a fllter 13 acting as a correction network. I~
an FM demodulator 14 a video signal 16 is obtained : at a terminal 15~ e filter 13 serves to raise the .
lower side band of the carrier 17 in order to correct . :
1', . ~ ~ - ,. ;
.. . . , . , . ~ . ~ ~, .. .. ... . .. ... . . . .. . . .
~0~ 358 th~ ~r~(luency re~pons~ of tlle sc~nner~
'l'he frequency curve of the filter 13, i.e. the lowering of the lower side~band is changed in dependence on the respect1ve diameter,oL the track i.e. the respective position of the scunner 7 on a radius ~,, of the video disc ~, us indicated by the variable resistor 21 in the filter 13. 'l~lis change i~ caused by the drive 10 via a mechànism indicated by the broken line 18~ ln addition the variable resi~tor 21 of the filter 13 for example is mechanically coupled to the radial feed of the carriage 8. 'l'he resistor .!' .
21 may be a potentiometer the axle of which is : coupled to the drive of the cord 9. '~le change in , : correction may also take place via an element otherthan a variable ohmic re~istor~ Ba~ically the use of a variable inductance or capacitance (Varicap diode) is po~sible in an appropriate network.
,,1,.
~ Figure 2 ~how~ the curve of the scanner 7, i.e~
: , the amplitude of the outpu~ signal ~ in dependence on .' ., I " . ~ .
the recorded wavelength, in a ~tandard view for S. When . there is a constant frequency deviation in the recorded .. . ... .
carrier, the frequency deviation range 19 shown as a hatched area occurs at the outer end of the track as a .....
re~ult of the:lowering relative ~peed towards the inner part of the disc and the fre~uency deviation range 2U
shown as a hatched area occur~ atl.the inner end of the track . 'lhese ra~ges are e~ual to one another. ~tarting frolll tll~ deviation range ~, ir ~ ectr~l line of the frelIuency Inodulated carrier :is con9idered ~t a ~paci~g i~ fro~n the centre fre(Iuency toward~ tI~e lower side band then ~llere is a ri~e in tll~ lower side bund by the amount ~. 'l'Ilus tIIe filter 13 woul~ IIave to lower the lower ~ide band by tIIis uMount ~t this spectral line. At the fre~uency deviation 1~, thu~ ut the outer diameter o~
the track when there is an e-lual ~pacing A of the sp~ctral line from the centre frecIuency, there is only a rise in the lower side ban~,by the amount ~'. lt can be seen th~t ~' < B. 'rhus, at ,tlie outer diameter of the track ~ smaller lowering of:.the lower side band is .. .;~
neces~ary. This matching of~the lowerlng of the lower side band in accordance with the respective diameter of the trar,k durin~,,scanning is carried out by tlle filter 13 in Figure 1, controlled by the drive 10.
e rise in the,lower side band means a rise in high fre~uency emphusi~. '~1iS emphasi~ must not be made ~: resettable,but rather the difference in the rise is resettable. ~ constant rise,can be com~letely desirable, Fi~ure 3 show~ ~a practical development of the filter i3. The re~istor 21'~hich i~ varied in dependence on the radiu~ causes a lowering of the lower side band dependent on radius. The fre~Iuency modulated carrier ; ~
17 is supplied to the terminal 22 by the scanner 7 while ~ :
~, the output terminal 25 in Figure 1 is connected to the demodulator 14.
Figure 4 shows another development o~the filter 13.
'. .
~Ol~Z35t~
~ ur~ 5 sllows u ~rou~ of curve~ and in fuct lowerin~ of the lower side band of the frequency modul~ted ci~rrier 17 with ,tlle respective disc radius r i~S a paramet~r. It muy be se~n that t~le loweringo~
tlle lower side band increases as the rudius 'become smaller, thus toward~ the inn~r part of the disc.
Figure 6 shows the dep~ndence of lowering of the lower end of ~he lower side band and in ~'act at a fre~uenicy of approximately~l MUlz in dependence on the respec~ive radius as is pro~iuced from Figure 5. It may be seen that lowering at the inner edge of the recording track initially changes to ~ v~ry large ~ extent and at the outer edge it change~ to a les~er , , '~ extent. This may be obtai~ed by means of special dimensioning of the filter,',,13, e.g. by means of a 'i¢y ;~ logarithmic potentiometer',~
..
~'igure~7 shows a further;group o~ curves for the lowering during reproduction which 18 simi;lar ln principle ' to that in ~i~igure 5.
~ Figure 8 ~how~ a curve for recordlng and in fa~t shows the lowering o~the lowermost side band :
fre~uency (0.5 - 1 MH~) in dependence on the respective radiu~ of the recording trackO It may be seen that th~re the lowering is smaller than during reproduction.
In princlple the filters according to Flgures 3 and 4 may also be used for the lowering during recording.
.
, ., . .: .. 7, , ... :.. , .. __ .,~_ .. , _. _ ._ .. ,. _ .. _.. , .. _ , . . . ..
- :
In practi e howev`er the tran~ducer has a charucter-i~tic curve according to which its outpu~amplitude ~ :
- . ~ -decreases as the wavelength drops.~ When recording, this ~: : mean~ that the mechanical~mo~ement~amplitude for a cutting proce9s wlth a dropping waveleDgt~:is ~maller with a : :
con~bant eontrol voltage ~or the tran8ducer. It i~ al~o po~sible that, in:fact, the mecbanical de~leotion ampli-tude-re~in~ the same yet the amplitude of the ~ignal cut into the disc decrease3 as the wavelength drop~, becau~e there i~ a lack~of:sharpnes~ of the cutting ~tylu~
~uring repro~uction, the output amplitude of the electrical signal supplied by the, for example mechanical-electrical, tra~sducer drops accordingly a~ ~
~ ~, :
t~; ' ', ~ 8Z3SI!~
the wav~lengtll dro~
l~ecording of th~ vid~o si~nul takes place ~enerully in the rorm of a fre~uency mo~ulated carrier. As fairly large wavelengths, i.e. low frequencie~, have u higher output amplitude according to the ~tated curve of the tran~ducer than ~mall wavelengths, i.e. high fre~uencie~, then there is a rise in the lower side band of the fre~uency modulated carrier. 'l'hereLore it is nece~ury to lower the lower ~ide band of the frequency modulated carrier with a filter according to the characteristic curve. The upper ~id0 band will not be considered in greater detail below becau~e in genarnl only the lower side band is utilized duri~g reproduction and the uppar side band is omitted.
In practice, it has been proved that when there is this type o~ correction, given a large track diameter, i~e. at the outer edge of the video di~c where the a~erage wavelengths are large, the ~harpne~ o~ the image reproduced is poor and the ~ignal to noise ratio is relatively smallO On the other hand with a small track diameter, i~e. at the~inner edge of the di~c the sharpness is relatively good ~hil~`~h~ ~nter~erence ~pacing is ~all. ~ mus ~harpnes~and interference . . .
spacing are not constant o~er the entire length of the recording track.
The invention seeks to provide means by which the sharpne~s ~and signal to noise ratio may be made as independent as pos`sible of the respective track diameter 1t~8~358 90 that th~y r~main substuntially unch~ed during playing of a disc.
l~ccording to tl~e invention, there is provided a device for recording or re~roducing a video signal in the form of a frequency modulated carrier on a spiral ; 5 track of u video disc comprising a tr~nsduc~r used during recording or reproduction nnd having an output signul whose ~mplitude decreases as the re¢ordèd wave-length drops and a fre~uency selective filter for lowering the amplitude of the lower side band of the : carrier.to an increasing extent as the di~meter of the track decreases.
Further according:to the in~entlon, there i~
provided a device for recordin~ or reproducing a video signal along a spiral tr~ck of a video di~c in the ~orm of a ~requency modulated carrier, wherein the amplitude of the output signal of the transducer used durlng recording or reproductio~ decreases~:as the recorded wavelength drop~ ~nd a fre~uency selective filter is provld~d ~or lowering the amplitude 4f.~the lower side band - 20 ~ ~ of the carrier with rospect to the;carrier, characterized : ~ in-that't'he curve of the ~ilter i~ dependent o~ the re~pective diameter of the track ~uch tha~t the~lowering increa8e~ as the diameter of the track decreases.
~ .
A video dlsc~player~is known (German O~fen-legungsschrift No. 2,503,944) in which,~when there is spiral scanning, the change in the transmlssion function (dependence of the amplitude of the ~canned signal on the fre4uency3 is taken into account by means of a filter as , : ~
th~ ~iumet~r of tll~ truck ~ecr~u~es, s~ ilter lying in the prlt~l of tlle scanned fre~uency Ino~ulate~
curri~r. ~itll this circuit, however, the wllplitude o~ a ~)ilot sigrnal recorde~ at constant umplitude is evaluuted ,md the pass region of the filter i~
changed in dependence ther~on. ~irect control of the decrease in am~litude of the lower side b~nd of the scu~ned fre~uency modulated currier is not provided in depend~nce on the respective scanning radius. The filter does not cause any variable lowering in amplitude of the lower side band and the res~ective position of the scanner radially to the vldeo disc is ulso not directly evaluated. 'l'his ~rrangement does not deal with holding the shar~ness and interference spacing as constant as possible over the length o~
the track, is not dealt wlth here.
'~hu~ 7 the varying gradient of the stated curve of the transducer is taken into consideration witl large and small wavelengths, so that~ correction is matched in each case to the re~uireme~ts of a certain track diameterr 'l'he correction which takes place and is dependent on the radius, may be used basically when recording or reproducing or both simultaneously. ~orrection during recording ~ay also :
take the distortion brought about by the transducer curve during reproductio~ into consider~tion eith~r completely or partially. ~orrection during reproduction may also either completely or partially balance out .
~ .
~' ' . . ~ ' J 0l~il23SI~
distortion which has occurred as a resul-t of the t.ransducer curve during recording.
The invention is preferably used with so-called pressure scanning, as is described in our Canadian Patent No.
923,046 issued March 20, 1973 and our Canadian Patent No.
942,682 issued February 26, 1974. It is not however restricted to a certain recording method but may be used generally for a spiral recording having different relative speeds between the scanner and the disc. The lowering of the lower side band is generally less during recording than during reproduction.
The invention will now be described in greater detail by way of example with reference to the drawings in which:
Figure 1 shows a general circuit diagram of the arrangement;
Figure 2 shows characteristic curves of the scanner :
for the purpose of illustrating the mode of operation;
Figures 3 and 4 show embodiments for the filters . used; .
Figure 5 shows a group of curves for the decrease in accordance with the invention, which decrease is dependent on radius;
Figure 6 shows the dependence of the decrease on the radius of the video disc at a frequency of 1 MHz;
=:~
. . .
lilZ358 I~'igure 7 Silo~S a furtller group o~ curves ~or reproduction, and ~`igure 8 shows u curve for recording for the lowermost side band fre~luency of approximately 1 ~lz~
ln Fi6ure 1 a video disc having u drive dog is coupled to a shaft 3 of a drive motor 4. 'l'he video disc 1 rotates above a fixed support 5 on an air cushion 6. Sc~nning take~ place by : 10 means of a scanner 7 whioh i~ fixed to a carriage 8. 'l'he carriage 8 is pas~ed over the vldeo disc 1 in a radial direction by means of a drive 10 throu~h - a cord 9, according to the gradient of the spiral 4.' recording track~ '~he exact guidance of the scanner takes place by means of the mechanically cut groove and by means of d resilient mounting of the scanner 7 on`the carriage 8. lrhe signals are recorded mechanically on the Yideo disc~1 ln the : :~
form of a fre~uency modulated car~ler for scanning 20 ~ according to the pressure scanning prin~iple. 'l~e drive 10 is also controlled by the motor 4 as is indicated by the broken llne 11. T~le signal remo~ed by the scanner 7 in the form of a carrier 17 frequency modulated with the video signal is suppled ~ia a line "~
12 to a fllter 13 acting as a correction network. I~
an FM demodulator 14 a video signal 16 is obtained : at a terminal 15~ e filter 13 serves to raise the .
lower side band of the carrier 17 in order to correct . :
1', . ~ ~ - ,. ;
.. . . , . , . ~ . ~ ~, .. .. ... . .. ... . . . .. . . .
~0~ 358 th~ ~r~(luency re~pons~ of tlle sc~nner~
'l'he frequency curve of the filter 13, i.e. the lowering of the lower side~band is changed in dependence on the respect1ve diameter,oL the track i.e. the respective position of the scunner 7 on a radius ~,, of the video disc ~, us indicated by the variable resistor 21 in the filter 13. 'l~lis change i~ caused by the drive 10 via a mechànism indicated by the broken line 18~ ln addition the variable resi~tor 21 of the filter 13 for example is mechanically coupled to the radial feed of the carriage 8. 'l'he resistor .!' .
21 may be a potentiometer the axle of which is : coupled to the drive of the cord 9. '~le change in , : correction may also take place via an element otherthan a variable ohmic re~istor~ Ba~ically the use of a variable inductance or capacitance (Varicap diode) is po~sible in an appropriate network.
,,1,.
~ Figure 2 ~how~ the curve of the scanner 7, i.e~
: , the amplitude of the outpu~ signal ~ in dependence on .' ., I " . ~ .
the recorded wavelength, in a ~tandard view for S. When . there is a constant frequency deviation in the recorded .. . ... .
carrier, the frequency deviation range 19 shown as a hatched area occurs at the outer end of the track as a .....
re~ult of the:lowering relative ~peed towards the inner part of the disc and the fre~uency deviation range 2U
shown as a hatched area occur~ atl.the inner end of the track . 'lhese ra~ges are e~ual to one another. ~tarting frolll tll~ deviation range ~, ir ~ ectr~l line of the frelIuency Inodulated carrier :is con9idered ~t a ~paci~g i~ fro~n the centre fre(Iuency toward~ tI~e lower side band then ~llere is a ri~e in tll~ lower side bund by the amount ~. 'l'Ilus tIIe filter 13 woul~ IIave to lower the lower ~ide band by tIIis uMount ~t this spectral line. At the fre~uency deviation 1~, thu~ ut the outer diameter o~
the track when there is an e-lual ~pacing A of the sp~ctral line from the centre frecIuency, there is only a rise in the lower side ban~,by the amount ~'. lt can be seen th~t ~' < B. 'rhus, at ,tlie outer diameter of the track ~ smaller lowering of:.the lower side band is .. .;~
neces~ary. This matching of~the lowerlng of the lower side band in accordance with the respective diameter of the trar,k durin~,,scanning is carried out by tlle filter 13 in Figure 1, controlled by the drive 10.
e rise in the,lower side band means a rise in high fre~uency emphusi~. '~1iS emphasi~ must not be made ~: resettable,but rather the difference in the rise is resettable. ~ constant rise,can be com~letely desirable, Fi~ure 3 show~ ~a practical development of the filter i3. The re~istor 21'~hich i~ varied in dependence on the radiu~ causes a lowering of the lower side band dependent on radius. The fre~Iuency modulated carrier ; ~
17 is supplied to the terminal 22 by the scanner 7 while ~ :
~, the output terminal 25 in Figure 1 is connected to the demodulator 14.
Figure 4 shows another development o~the filter 13.
'. .
~Ol~Z35t~
~ ur~ 5 sllows u ~rou~ of curve~ and in fuct lowerin~ of the lower side band of the frequency modul~ted ci~rrier 17 with ,tlle respective disc radius r i~S a paramet~r. It muy be se~n that t~le loweringo~
tlle lower side band increases as the rudius 'become smaller, thus toward~ the inn~r part of the disc.
Figure 6 shows the dep~ndence of lowering of the lower end of ~he lower side band and in ~'act at a fre~uenicy of approximately~l MUlz in dependence on the respec~ive radius as is pro~iuced from Figure 5. It may be seen that lowering at the inner edge of the recording track initially changes to ~ v~ry large ~ extent and at the outer edge it change~ to a les~er , , '~ extent. This may be obtai~ed by means of special dimensioning of the filter,',,13, e.g. by means of a 'i¢y ;~ logarithmic potentiometer',~
..
~'igure~7 shows a further;group o~ curves for the lowering during reproduction which 18 simi;lar ln principle ' to that in ~i~igure 5.
~ Figure 8 ~how~ a curve for recordlng and in fa~t shows the lowering o~the lowermost side band :
fre~uency (0.5 - 1 MH~) in dependence on the respective radiu~ of the recording trackO It may be seen that th~re the lowering is smaller than during reproduction.
In princlple the filters according to Flgures 3 and 4 may also be used for the lowering during recording.
.
, ., . .: .. 7, , ... :.. , .. __ .,~_ .. , _. _ ._ .. ,. _ .. _.. , .. _ , . . . ..
- :
Claims (12)
1. A device for recording or reproducing a video signal along a spiral track of a video disc in the form of a frequency modulated carrier, wherein the amplitude of the output signal of the transducer used during recording or reproduction decreases as the recorded wavelength drops and a frequency selective filter is provided for lowering the amplitude of the lower side band of the carrier with respect to the carrier, characterized in that the curve of the filter is dependent on the respective diameter of the track such that the lowering increases as the diameter of the track decreases.
2. A device as defined in Claim 1, and comprising a variable component in said filter having a variable displaceable part coupled to the drive of a carriage for moving said transducer radially with respect to said video disc.
3. A device as defined in Claim 2, wherein said displaceable component comprising a potentionmeter with its axis is coupled to the drive of said carriage.
4. A device as defined in Claim 1, wherein said filter includes a series circuit of a parallel RC
element and an inductance in its longitudinal path.
element and an inductance in its longitudinal path.
5. A device as defined in Claim 1, wherein said filter includes a parallel RC element in its longitudinal path and a series circuit of an inductance and a resistor in a cross-wise path connected after the parallel RC element.
6. A device as defined in Claim 4 wherein said resistor of said RC element is variable in dependence on the diameter of the track.
7. A device as defined in Claim 5 wherein said resistor of said RC element is variable in dependence on the diameter of the track.
8. A device as defined in Claim 1 wherein said frequency responsive filter comprises a filter with a drop at the lower boundary of the lower side band changing, during reproduction, approximately by 12-20 db when the track diameter varies from 105-45 mm.
9. A device as defined in Claim 1, wherein said curve of said filter has a curve whose gradient increases as the diameter of the track decreases and represents a lowering of the side ban amplitude in dependence on the diameter of the track at a certain side band frequency.
10. A device as defined in Claim 1, wherein, when recording, lowering of the amplitude of the lowermost side band frequency (0.5 - 1 MHz) changes from the outer to the inner diameter of the track by approximately 6db.
11. A device as defined in Claim 10, wherein said lowering of said amplitude of said lower side band changes in linear manner with the respective radius of said track.
12. A device for recording or reproducing a video signal in the form of a frequency modulated carrier on a spiral track of a video disc comprising a transducer used during recording or reproduction having an output signal whose amplitude decreases as the recorded wavelength drops and a frequency selective filter for lowering the amplitude of the lower side band of the carrier to an increasing extent as the diameter of the track decreases.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2547431A DE2547431C3 (en) | 1975-10-23 | 1975-10-23 | Device for recording or playing back a video signal |
| DEP2547431.1-31 | 1975-10-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1082358A true CA1082358A (en) | 1980-07-22 |
Family
ID=5959866
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA263,903A Expired CA1082358A (en) | 1975-10-23 | 1976-10-21 | Device for recording or reproducing a video signal |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS5278310A (en) |
| AT (1) | AT348037B (en) |
| AU (1) | AU502757B2 (en) |
| BE (1) | BE847455A (en) |
| CA (1) | CA1082358A (en) |
| CH (1) | CH601953A5 (en) |
| DD (1) | DD129382A5 (en) |
| DE (1) | DE2547431C3 (en) |
| FR (1) | FR2329122A1 (en) |
| GB (1) | GB1565233A (en) |
| IT (1) | IT1068865B (en) |
| NL (1) | NL7611552A (en) |
| SE (1) | SE416257B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5948447B2 (en) * | 1977-07-20 | 1984-11-27 | ソニー株式会社 | Gain compensation circuit for signal regenerator |
| GB2035760B (en) * | 1978-10-16 | 1983-05-11 | Rca Corp | Playback apparatus with nonlinear correction |
| JPS6171470A (en) * | 1984-09-14 | 1986-04-12 | Olympus Optical Co Ltd | Waveform equalization circuit |
| IE883775L (en) * | 1988-12-19 | 1990-06-19 | Ocorralk Ltd | Signal wave form converting circuit |
| JPH03201264A (en) * | 1989-12-27 | 1991-09-03 | Sony Corp | Optical disk device |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3229048A (en) * | 1962-07-24 | 1966-01-11 | Rca Corp | Recording system |
| NL7402078A (en) * | 1974-02-15 | 1975-08-19 | Philips Nv | DEVICE FOR READING A DISK-SHAPED REGISTRATION CARRIER. |
-
1975
- 1975-10-23 DE DE2547431A patent/DE2547431C3/en not_active Expired
-
1976
- 1976-10-05 IT IT28006/76A patent/IT1068865B/en active
- 1976-10-05 CH CH1260076A patent/CH601953A5/xx not_active IP Right Cessation
- 1976-10-14 GB GB42788/76A patent/GB1565233A/en not_active Expired
- 1976-10-18 AU AU18772/76A patent/AU502757B2/en not_active Expired
- 1976-10-19 NL NL7611552A patent/NL7611552A/en not_active Application Discontinuation
- 1976-10-20 BE BE171646A patent/BE847455A/en unknown
- 1976-10-20 SE SE7611653A patent/SE416257B/en unknown
- 1976-10-21 CA CA263,903A patent/CA1082358A/en not_active Expired
- 1976-10-22 FR FR7631924A patent/FR2329122A1/en active Granted
- 1976-10-22 JP JP51127129A patent/JPS5278310A/en active Pending
- 1976-10-22 DD DD7600195410A patent/DD129382A5/en unknown
- 1976-10-22 AT AT789376A patent/AT348037B/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| ATA789376A (en) | 1978-06-15 |
| CH601953A5 (en) | 1978-07-14 |
| SE416257B (en) | 1980-12-08 |
| AU1877276A (en) | 1978-04-27 |
| SE7611653L (en) | 1977-04-24 |
| DE2547431A1 (en) | 1977-04-28 |
| JPS5278310A (en) | 1977-07-01 |
| IT1068865B (en) | 1985-03-21 |
| DD129382A5 (en) | 1978-01-11 |
| BE847455A (en) | 1977-02-14 |
| FR2329122A1 (en) | 1977-05-20 |
| DE2547431C3 (en) | 1978-04-06 |
| NL7611552A (en) | 1977-04-26 |
| AT348037B (en) | 1979-01-25 |
| FR2329122B1 (en) | 1983-02-04 |
| AU502757B2 (en) | 1979-08-09 |
| DE2547431B2 (en) | 1977-08-18 |
| GB1565233A (en) | 1980-04-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |