lZ~4;Z10 I BACKGROUND OF THE INVENTION
The present invention generally relates to recording and~or reproducing apparatuses for carrying out recording and/or reproduction wlth respect to a hollow and substantially cylindrical-shaped recording medium, and more particularly to a recording and/or reproducing apparatus constructed in a form of ¦ a so-called electron~c camera so that recording and~or ¦ reproduction can be suitably carried out with respect to a ¦ video signal obtalned by lmage-pickup.
) Recently, in additlon to efforts for reducing the size of a video signal magnetic recording and reproducing apparatus (so-called video tape recorder, and hereinafter simply referred to as a VTR), attempts have been made to reduce the size of an image pickup camera by combining a solid-state pickup element such as a charge coupled device (CCD) with integrated circuit (IC) technology. That is, a compact and light-weight apparatus referred to as an electronic 8 mm device, unitarily comprising the VTR and the camera, has been proposed.
; The above electronic 8 mm device has an advantage over the so-called conventional 8 mm movie camera using an optical 8 mm film, in that the picked up and recorded information can be reproduced on a television receiver immediately after the recording. In addition, the above electronic 8 mm device employs a magnetic tape using a metal-particle type magnetic material formed by a new magnetic layer forming technique, and a metal type head, to realize a greater recording density compared to the recording density of the conventional VTR, and the overall size of the whole device is reduced. The electronic 8 mm device essentially employs the i^``` lZ04Z10 1 recording and reproducing principle of a helical scan type VTR
! using a magnetic tape and rotary heads. Accordingly, although the electronic 8 mm device can carry out uninterrupted recording of moving pictures, without replacing once loaded 1 roll of medium, longer than that of the 8 mm movie camera, the electronic 8 mm device has the following disadvantages.
1) Normal recording of the moving pictures can be carried ¦ out, but a so-called still-picture-frame recording in units of l fields or frames cannot be carried out.
2) In relation to paragraph 1) above, recording in terms of picture frames wherein some randomly selected frames are replaced by new frames, and a random access reproduction, cannot be carried out.
l 3) A rotary drum provided with video heads, a tape ¦ loading mechanism for drawing out the tape from a tape cassette and loading the tape unto a predetermined tape path, a tape l travel driving mechanism for causing the tape to travel through ¦ the predetermined tape path, and the like, are essential to the l electronic 8 mm device, and it is difficult to achieve
0 ¦ substantial reduction in size and weight of the mechanical structure.
¦ 4~ The limit of the track pitch upon high density recording is in the order of 20 ~m from the practical point of l view because the tape slightly deviates upwards and downwards
5 ¦ while traveling on the tape path, and there is a limit in the size reduction of the electronic 8 mm device due to the fact ¦ that fine quality recording and reproduction cannot be I maintained if the track pitch is further reduced.
; ¦ 5) It is difficult to obtain tracking by swinging ¦ technology of the rotary heads, because the track pitch is I
l . .... ...
.~,~ ,, lZ~4210 1 I narrow as de~cribed above.
On the other hand, a so-called electronic camera which records the video signal onto a single side of a flexible I magnetic disc, has been propo6ed as a potential replacement of 1 the still picture camera using an optical 35 mm film. In this ¦ electronic camera, a magnetlc di~c having a diameter in the ¦ order of ~5 mm, for example, is rotated at a rotational speed ¦ of 3600 rpm within a main camera body having a size in the , range of a n~rmal 35 mm single-lens reflex camera. The video ~ignal obtained by pic~ing up an image by a solid-state pickup element such as a CCD is recorded magnetically onto the magnetic disc by a magnetic head. The magnetic head carries out recording in terms of one field for one revolution of the ¦ magnetic disc, and i8 successively mo~ed along the radial direction of the magnet~c disc. However, this electronic camera also suffers the following disadvantages.
a) Because the magnetic di~c is used as a recording medium and the picture of one picture frame is recorded for one l revolution of the magnetic disc, the magnetic disc is rotated ¦ at a constant angular speed. Hence, the relative linear ~peed between the magnetic head and the magnetic disc becomes smaller towards the inner periphery of the magnetic disc. Thus, in order to carry out recording in a normal manner, the central Il area of the magnetic disc is unusable and wasted, and the 25 il recording range i~ accordingly limited. On the other hand, i there is a limit to the diameter of the magnetic disc because the size of the main camera body i5 limited. Therefore, the effective recording area of the magnetic disc cannot be made large, and the recording capacity thus cannot be made large.
b) In relation to paragraph a) above, the picture quality lZ04Z10 1 'I of the recorded picture becomes poor towards lnnermost part of the disc whereat the relative linear speed between the magnetic ¦ head and the magnetic disc is small.
¦ c) A standing wave is likely to be introduced at the ¦ outermost periphery of the rotating magnetic disc because the ¦ magnetic disc comprises a flexible magnetic sheet such as a ¦ floppy disc. Hence, a flutter phenomenon may be observed on the magnetic disc due to the above standing wave, and the l magnetic head cannot make stable contact with the magnetic ¦ disc. As a result, the outermost peripheral part of the disc which i8 mo~t usable. whereat the relative linear speed between the magnetic head and the magnetic disc becomes large, cannot be utilized.
l On the other hand, a concept was conventionally known lS ¦ to construct a recording a,nd reproducing apparatus which uses a ¦ cylindrical-shaped rotary magnetic drum as a magnetic recording ¦ medium. In this apparatus which uses the magnetic drum, the ¦ relative linear speed between the magnetic head and the ¦ magnetic drum is constant regardless of the position of the ¦ magnetic hesd. However, the size of the recording and ¦ reproducing apparatus becomes large, because the recording ¦ capacity of the magnetic drum is not as large as the magnetic ¦ tape, and the size and volume of the magnetic drum is large.
¦ In addition, the handling of the magnetic drum is troublesome ¦ since the entire cylindrical surface of the magnetic drum is ¦ magnetic. Moreover, it i5 difficult to manufacture a magnetic ¦ drum compri~ing a good quality uniform magnetic surface.
Therefore, the magnetic recording and reproducing apparatus using the magnetic drum was not reduced to practice, for the above described reasons.
12~4Z10 1 ~' SU~RY OF THE INVENTION
Accordingly, it i8 a general obiect of the present ~ invention to provide a novel and useful recording and/or ¦ reproducing apparatus in which the above described ¦ disadvantages have been overcome.
¦ Another and more specific ob~ect of the present invention is to provide a so-called electronic camera type ¦ image pickup recording and/or reproducing apparatus. The ~ apparatus according to the present invention carrie~ out 1 recoxding and/or reproduction with xespect to a recording medium having a hollow and s~bstant~ally cylindrical-~hape opening at one end thereof, and a driving motor of the image l pickup recording and/or reproducing apparatus relatively enters ¦ within the hollow part of the recording med~um when the l recording medlum is loaded into the apparatusO ~ence, the overall ~ize of the recording and/or reproducing apparatu~ can be reduced, and the main apparatus body can be constructed to a ¦ size in the range of a conventional 35 mm single-lens reflex I , camera, so that the above hollow and substantially , cylindrical-shaped recor~ing medium can be easily loaded into the apparatus and used. In addition, the relative linear speed ¦ between a recording and reproducing transducer and the ! recording medium is substantially constant regardless of the position of the recording and reproducing transducer on the ¦ recording medium. Thus, the recording and/or reproduction can Il be carried out so that a reproduced picture of the same picture ¦¦ quality can be maintained throughout the entire recording ¦ surface of the recording medium.
¦ Still another object of the present invention is to ~30 ¦ provide an image pickup recording and/or reproducing apparatus 12~4;210 l which carries out recording and/or reproduction with respect to ¦ a magnetic drum when loaded with a recording medium which ls of ¦ a cartridge type wherein the hollow and substantially ¦ cylindrical-shaped magnetic drum ha~ing an opening at one end ~ thereof is accommodated within a hollow and substantially ¦ cylindrical-shaped case having an opening at one end thereof.
¦ The image pickup recording and/or reproducing apparatus ¦ according to the present invention is suited for constructing an apparatus of a portable type, since the magnetic surface of ~ the recording medium is p~otec~ed by the case, and the handling of the recording medium is fac~litated ~n that there is no need for special care upon handling.
Another object of the present invention is to provide an image pickup recording and/or reproducing apparatus which is ~ capabl~ of recording an image picked-up signal onto a hollow and substantially cylindrical-shaped recording medium, and l supplying a signal reproduced from the recording medium to a I television receiver through an adapter to reproduce the signal from the recording medium as a reproduced picture.
Other objects and further features of the present i invention will become apparent from the following deta~led description when read in conjunction with the accompanying , drawings. - l i BRIEF DESCRIPTION OF THE DRAWINGS
~5 1 FIG.l i~ a perspective view showing a first ¦ embodiment of an image pic~up recording and/or reproducing apparatus according to the present invention~ ! -FIG.2 is a perspective view, with a part cut away, showing a magnetic drum part of a first embodiment of a 12~gz~L0 1 1I recording medium used w~th respect to the apparatus according to the present invention;
FIG.3 is a perspective view showing an embodiment of a cartridge accommodating the magnetic drum shown in FIG.2 5 ¦ within a case;
¦FIG.4 is a perspective view from the bottom, with a part cut away, showing the cartridge shown in FIG.3t FIG.5 is a perspective view, with a part cut away, show~ ng a drive assembly within the apparatus ~hown in FIG. 1 s FIG.6 is a perspective view showing another example of a case of the magnetic drum cartridge7 FIG.7 is a side view in vertical cross section, showing a state where the magnetic drum cartridge shown in lFIGS.3 and 4 is loaded within the drive assembly shown in 1 FIG.5;
~FIG.8 is a perspective view, with a part cut away, ¦showing an embodiment of a magnetic head device within the apparatus shown in FIG.ls FIG.9 is a systematic block diagram showing an l embodiment of a signal system of the apparatus shown in FIG.15 : FIGS.lO(A) through lO(F) are graphs, respectively showing signal waveforms at each part of the block system ~hown Il in FIG.9;
¦!FIGS.ll(A) through ll(E) are graphs, respectively showing signal waveforms at other parts of the block system shown in FIG.9s FIG~12 shows a frequency~spectrum of a signal which is recordeds ~FIG.13 is a partially enlarged view showing an ¦ exa~ple of a recording pattern on the recording mediums 'i1 .
1 I FIGS.14~A~ through 14(F) are graphs showing signal~
¦ for explaining the operation of a reproducing system within the ~ block system shown ln FIG.9~
¦ FIG.15 ls a perspective view showing a second I embodiment of a recording medium used with respect to the apparatu~ according to the present invention3 .
FIG.16 is a perspective view, with a part cut away, ¦ showing a third embodiment of a recording medium~
FIG. 17 i5 an elevatlon in vertical cross section alon~ a line XVII-XVII in FIG.16;
FIG.18 is a view in vertical cross sect~on showing an example of a molding apparatus for molding the recording medium l shown in FIGS.16 and 17~
: FIG.l9 is a view in vertical cross section showing a ! state where the recording medium shown in FIGS.16 and 17 is loaded into a drive assembly;
: I FIG.20 is a perspective view, with a part cut away, , showing a ~econd embodiment of a cartridge accommodating a l~ magnetic drum within a case~
I FIG.21 is a view in vertical cross section along B
l~ne XXI-XXI in FIG.20~
FIG.22 ~s a perspective view, with a part cut away, ¦ showing a drive assembly which is loaded with the cartridge ~ shown in FIGS.20 and 21J
I FIG.23 is a view in vertical cross section showing a ~tate where the cartridge shown in FIGS.20 and 21 is loaded lnto the drive assembly shown in FIG.22 I FIG.24 i8 a view in vertical cross section showing a ¦ magnetic drum cartridge provided with another modification of a rotational phase detecting means and the loaded state of the _ g_ I~ l lZ~:)4Z10 1l 1 1 drive assembly;
FIG.25 is a partial view in vertical cross section ! showing another embodiment of a connection between a rotary I plate fixed to a rotary shaft of a motor and an upper end ¦ surface part of a magnetic drum;
FIG.26 is a perspective view showing an embodiment of ~ a magnetic head;
! FIG.27 is a perspective view showing another l embodiment of a magnetic headt 10 ~ FIG.28 is a view in vertical cxoss section showing another embodiment of a cartridge case;
~ IGS.29A and 29B are views in vertical cross section respecti~ely showing still another embodiment of a cartridge l case in an unoperated state and an operated state;
15 1 FIG.30 is a view in vertical cross section showing a further embodiment of a cartridge caseS
¦ FIG.31 is a view in vertical cross section showing 1 another embodiment of a drive assembly in a state where a . i cartridge is loaded thereins 20 l'' FIG.32 is a view in vertica~ cross section showing a fourth embodiment of a recording medium;
FIG.33 i8 a view in vertical cross section showing a i fifth embodiment of a recording medium;
Il FIG.34 is a general perspective view showing a second 25 ll embodiment of a recording and/or reproducing apparatus according to the present invention, together with devices which cooperate therewiths FIG.35A is a systematic block diagram showing a circuit of the recording and/or reproducing apparatus shown in ¦ FIG.34t and I 12~4210 .
1 1 FIG.35B is a systematic block diagram showing a circuit of an adapter within the apparatus shown in FIG.34.
1 First, general description will be given with respect ¦ to an embodiment of an image pickup recording and/or ¦ reproducing apparatus according to the present invention. An ¦ image pickup recording and/or reproducing apparatus 10 comprises an external frame 11 which has a shBpe generally ¦ similar to a 35 mm single-lens reflex camera. Although the external ~rame ll is shown in a perspective view as a transpaxent frame for convenience' sake in order to explain the inner construction thereof, the external frame 11 i8 actually l opaque. Light from an o~ject (not shown) which is to be image ¦ picked up and recorded passe~ through a lens system 12 and a ¦ hal~ mirror 13, and is then projected to a solid-s~ate pickup ¦ element 14 comprising a CCD, for exa~ple. The light thus ¦ projected to the pickup element 14 i5 converted into a video signal. A part of the light which is passed through the lens I system 12 is reflected at the half mirror 13 to reach a view finder 16 after being further reflected at a mirror 15. A
battery 17 is a power source to a printed circuit device 18 l provided with the image pickup element 14, a motor 24 which I will be described hereinafter, and the like. Similarly as in a 1 normal camera, a shutter button 19, a release button 20, and an operation switch 21 are provided on the upper surface of the external frame ll. ~ ¦
A magnetic drum cartridge 22 is loaded into or ¦-unloaded from a drive assembly 40 within the apparatus lO, by ¦ opening a lid 23. The cartridge 22 is hollow, and the motor 24 Il , 4Z~O
1 ll is relatively inserted within the cartridge 22 in its loaded state, as will be described hereinafter. A feed screw 25 is ¦ rotated by the motor 24 by way of a belt 26. A feed nut 27 is ¦ screwed onto the feed screw 25, and a magnet~c head device 28 ¦ is mounted on the nut 27. The magnetic head device 28 moves ¦ upwards or downwards as the feed screw 25 rotates.
¦ The above cartridge 22 has a shape shown in FIGS.3 and 4, for example. A first embodiment of a magnetic drum 30 ! within the cartridge 2~ has a shape shown in FIG.2, The 1 magnetic drum 30 i8 of a hollow cylindrical-shape comprising a hollow part 30a which has an open lower end. A magnetic layer covers the outer peripheral surface of the magnetic drum 30, to form a magnetic surface 31. A mounting hole 32 is provided at l the central upper surface of the magnetic drum 30. A
1 ring-shaped projection 33 having a diameter greater than that of the mounting hole 32, is formed at the upper surface of the magnetic drum 30. A small diametral part 34 having a diameter slightly smaller than the outer diameter of the magnetic surface 31, is provided on the outer surface of the magnetic I drum 30 at the lower end part thereof, to provide a step part.
In addition, a tapered surface 35 is formed on the inner ! surface of the magnetic drum 30 at the lower end part thereof.
¦ As shown in FIGS.3 and 4, the above magnetic drum 30 Il is accommodated within a case 36, to constitute the magnetic 1 drum cartridge 22. The ~agnetic drum 30 is loaded and unloaded with respect to the apparatus 10 in a state accommodated within the case 36, and thus, there is no direct contact between the operator's hands and the magnetic surface 31, and dust ll particles and the like are prevented from adhering onto the ¦ magnetic ~urfaco 31. A window 37 ls formod along the l, 1 ~Z042~0 1 ll longitudinal direct~on of the case 36, that is, along a direct~on parallel to the axial core of the magnetic drum 30.
Ribs 38a and 38b are formed on the outer surface of the case l 36, along the longitudinal direction theresf. A holding cap 39 is provided on the inner periphery at the upper end of the case ¦ 36. A flange part 36a bent towards the inner peripheral ¦ direction, is formed on the lower end part of the case 36.
When assembling the cartridge 33, the magnetic drum 30 is ~ inserted into the case 36 from above in a state where the holding cap 39 is r~moved 80 that the magnetic drum 30 is ¦ accommodated within the cartridge 22, and the holding cap 39 ls ¦ thereafter mounted. The magnetic drum 30 is prevented from ~ slipping upwards out of the cartridge 22 by the holding cap 39, ¦ and prevented from slipping downwards out of the cartridge 22 ~15 ¦ by the engagement with the step part formed by the small diametral part 34 and the flange part 36a of the case 36.
When the cartridge 22 operates in a state loaded into the drive assembly 40 as will be described hereinafter, the l case 36 remai~ stat~onary and only the magnetic drum 30 20 1 rotates. Thus, the outer diameter and length of the magnet~c drum 30 are set smaller than those of the case 36. Hence, by taking into account the error introduced ln positioning the magnetic drum 30 along the radial direction and the thrust ¦ direction upon loading, there is play between the magnetic drum 30 and the case 36. However, in order to prevent damage to the magnetic surfa~e 31 of the magnetic drum 30 upon handling of the cartridge 22, the above play ~etween the magnetic drum 30 ¦ and the case 36 must be selected so that there is no contact ~ between the magnetic surface 31 and the inner peripheral surface of the case 36.
lZ~4Z10 1 ¦ The present inventor has devised possible means for:
(1) preventing rotation or play in the magnetic drum 30 by engaging a cam-shaped finger with the magnetic drum 30 or providing a pushing spring with respect to the magnetic drum 30~ (2) providing a suitable cushion member at the inner ¦ ~urface of the case 36; (3) shaping the magnetic drum 30 so ¦ that the magnetic surface 31 does not make direct contact with ¦ the case 36; and the like, in a state where the cartridge 22 is not loaded into the drive assembly ~0. The means ~3~ is ¦ employed in the above descri~ed embodiment, by taking lnto ~ account the manufacturing ease, the manufacturing cost, and the ¦ like. That is, the movement of the magnetic drum 30 in the ¦ radial direction is rPstricted by the contact between the small diametral part 34 and the flange part 36a, and the contact between the ring-shaped projection 33 and the holding cap 39.
The magnetic surface 31 of the magnetic drum 30 ls accordingly l separated from the inner peripheral surface of the case 36, due i to the above structure. Accordingly, the magnetic surface 31 l does not make rubbing contact with the case 36. In addition, 1 the play in the magnetic drum 30 along the thru~t direction is restricted by the above construction which prevents the magnetic drum 30 from slipping out of the case ~6 in the upward ~¦ and downward directions.
ll As shown in FIG.5, the drive assembly 40 of the apparatus 10 generally compri~es the motor 24, a drum holder ¦ 41, and a hollow cylindrical-shaped case holder 42. When ¦ loading the cartridge 22 into the drive assembly 40, the dxum ¦ holder 41 is relatively inserted within the hollow part 30a of ¦ the magnetic drum 30. Moreover, the case 36 i8 inserted within the case holder 42 in a state wh-re the projections 38a and 38b Il l lZ~)4Z10 1 ' on the case 36 engage with guide grooves 43a and 43b of the case holder 42, as the case 36 is inserted within the hollow ¦ part of the case holder 42 together with the lnsertion of the cartridge 22 into the drive assembly 40 from above the drive assembly 40. A set ~crew 44 which fits within the mountlng hole 32 of the magnetic drum 30, projects from the central ¦ upper surface of the drum holder 41~ ~ tapered surface 45 i8 formed on the lower part of the drum holder 41.
A part of the case holder 42 is cut out along the longitudinal direction (~ direction parallel to the axial core) to form a cutout 47, and the magnetic head 46 of the magnetic head device 28 is positioned opposing a cuto~t 47. The case 36 is ~nserted ln a direction so that the window 37 opposes the magnetic head 46 through the cutout 47, by the positioning prov~ded ~y the projections 38a and 38b and the guide grooves 43a and 43b. It is not essential to provide two pairs of these projections and guide grooves, and it i5 sufficient to provide only one pair of projection and guide groove. I~hen providing two pairs of pro~ections and guide grooves as in the above described embodiment, it is desirable to provide the projectlons and guide grooves at positions deviated from diametrical positions in order to prevent insertion of the case 36 in the reverse direction. The relationship between the . above projections and guide grooves may be opposite, that is, ¦ the pro~ections may be provided on the case holder 42 and the guide grooves may be provided in the case 36.
As will be described hereinafter, the magnetic drum ¦ 30 of the cartridge 22 loaded into the drive assembly 40, iæ
~ rotated together with the drum holder 41 by the motor 24. The ¦ magnetic head 46 of the magnetic head device 28 is f~d I . '.
~Z~4Z10 1 continuously or intermittently by the feed screw 25 and the feed nut 27. As a result, an informatlon signal such a~ the video signal i~ recorded and reproduced with respect to the ¦ magnetic surface 41 by the magnetic head 46 on spiral or ¦ concentric tracks.
¦ Next, description will be given with respect to an ¦ embodiment showing practical size and rotational speed of the ¦ magnetic drum 30.
When taking into consideration the fact that the ~ize ! of the external frame of the apparatus 10 shown in FIG.l is to be in the range of the existing 35 ~m optical camera it is desirable for the size of the magnetic drum 30 to be in the range of a patronat of the existing 35 mm film (47 mm in length l and 25 mm in diameter) or in the range of a patronat case which ¦ accommodates the above patronat (53 mm in length, 31 mm in case l d~ameter~ and 34 mm in cap diameter).
: ¦ On the other hand, in the portable type VTR for home ¦ use which is presently most popular throughout the world, the ¦ diameter of a drum provided with two rotary heads is selected ¦ to 62 mm, and the rotational speed of the drum is selected to 30 rps. Thus, the relative linear speed between the magnetic tape and the heads i5 selected to 5.8 m/sec. Fine quality recording and reproductlon of the video signal is realized by ¦ selecting the relative linear speed between the magnetic 1 recording medium and the heads to the above value.
As a preferable embodiment, if the relative linear speed between the magnetic surface .31 of the magnetic drum 30 and the magnetic head 46 is selected to 5.8 m/sec, the diameter ~ ¦ and the rotational speed of the magnetic drum 30 are ;30 ¦ respectively set to 31 mm and 60 rps. In addition, if the Il lZ~4;2iO
1 , length of the magnetic drum 30 is selected in the range of 50 mm, the slze as a whole can be set to a size substant~ally the 11l same as that of the patronat case of the 35 mm film.
Il Next, description will be given with respect to the il features of the magnetic drum 30, in comparison with the magnet~c disc used in the previously described electronic camera. If the diameter and rotational speed of the magnetic l drum 30 are respectively selected ~o 31 mm and 60 rps (3600 I rpm), the relative linear speed of 5r 8 m/sec i~ obtained 1 between the magnetic drum 30 and the magnet~c head 46. ~hu6, one field of the television video signal which is picked up, can be recorded for one revolution of the magnetic drum 30.
Moreover, because the diameter of the magnetic drum 30 iB
substantially the same throughout the entire length of the magnetic surface 31 ~50 mm of length in the above example), the j relative linear speed is maintained same0 and the recording and i reproduction can effectively be carried out with the same performance characteristic throughout the entire length of the il magnetic surface 31. If an electronic tracking technique ~s ¦ applied with respect to the magnetic head 46, the recording and reproduction may be carried out on a narrow track wherein the track width is 3~m and the guard band iæ 1.5 ~m (track pitch of 4.5 ~m), for example. Accordingly, if the moving range of the I magnetic head 46 with respect to the magnetic surface 31 having 1 25 ~ a length of ~0 mm is selected to 48.6 ~m, for example, 4B.6 mm/4.5 ~m - 10800 tracks can be ~ormed on the magnetic drum 30.
Therefore, when recording and reproducing still pictures, more than 10,000 picture frames of still pictures can be recorded and reproduced. On the other hand, when continuously recording and reproducing motion pictures to carry out normal recording Il I .
j, ~Z~4~0 I I and reproduction, 10,800/60 x 60 = 3, that is, three minutes of full-field normal recording and reproduction can be carried out. If a so-called field-skip recording is carried out wherein the recording is carried out for every second field, 5 I si~ minutes of recording and reproduction can be carried out because there are thirty picture frames per second in this ~ case.
,1 In the conventional 8 mm film camera, there are sixteen picture frames per second, and the pickup time or playback duration of one roll of film is three minutes. Hence, according to the above recording medium , an information quantity twice that of the 8 mm film can be recorded for a given time or duration even if the field-skip recording is carried out. Furthermore, the recording duration becomes twice that of the 8 mm film. Accordingly, the above recording medium may not only be used instead of the conventional 35 mm still picture camera, but may even replace the conventional 8 mm film camera.
¦ On the other hand, if a performance equivalent to the performance OL the magnetic drum used with respect to the ¦ apparatus according to the present invention was demanded with ¦ respect to the magnetic disc of the previously described ¦ electronic camera, the diameter at the above innermost ¦ peripheral position on the magnetic disc would become eq~al to l 31 mm in order to obtain a relative linear speed of 5.8 m/sec ¦ between the magnetic disc and the magnetic head. Thus, in ¦ order to obtain the above recording capacity by starting the ¦ recording from the innermost peripheral position on the ¦ magnetic disc, a recording range of 50 mm along the radial ~ direction of the magnetic disc would be required from the I ~ - 18 -~1 lZ~4210 1 innermost peripheral position, and the diameter at the ¦ outermost peripheral position would be equal to 131 mm as a result. However, it is impossible to accommodate a magnetic disc having such a large diameter within a frame body having a size in the range of the 35 mm camera. Conversely, if the size of the magnetic disc is selected so that the magnetic disc can ¦ be accommodated within the frame body having the size in the ¦ range of the 35 mm camera, the relative linear speed between the magnetic disc and the magnetic head is reduced, and great 10 ¦ reduction is introduced in the recording capacity as compared to the magnetic drum. It can be clearly under tood from the above description that the above magnetic drum is superior when carrying out the recording and reproduction in a state where l the magnetic drum is accommodated within the frame body having a size in the range of the 35 mm camera.
It is not essential for the case of the magnetic drum I cartridge to have a cylindrical-shape as long as the magnetic I drum 30 can rotate therein, and a substantially parallelepiped-I ¦ shaped case 50 shown in FIG.6 may be used. In this case, a 1 window 51 similar to the above window 37 is provided in the I case 50, and a cutout 52 is provided at one corner part of the case 50, for positioning. A case holder of a drive assembly which is loaded with a magnetic drum cartridge 53 having the I above construction, is formed in a hollow substantially parallelepiped-shape so that the case 50 can be inserted l therein.
¦ FIG.7 is an enlarged vie~ in cross section showing a state where the cartridge 22 is loaded into the drive assembly l 40. A~ described above, in the state where the cartridge 22 is 1 aded into the drlve assembly 40, the case 36 rects on and ic ll lZ~4210 1 ll supported by a step part 42a of the case holder 42. Further, the tapered surface 35 at the lower end of the magnetic drum 30 ~ rests on the tapered surface 45 of the drum holder 41. The set ¦ screw 44 penetrates through the mounting hole 32 in the ¦ magnet~c drum 30, and the magnetic drum 30 is mounted onto the ¦ drum holder 41 by a nut 60. In th-s state, the magnetic drum ¦ 30 does not make contact with the case 36, that is, separated ¦ from the inner peripheral surface of the case 36, and ~s rotatable therein together with the drum holder 41. Here, even if the magnetic drum 30 is given a certain thickness for mechanical strength, the inner diameter of the hollow part 30a of the magnetic drum 30 can still be 20 mm when the diameter of the magnetic surface 31 is set to 31 mm, and further, the length of the hollow part 30a can be in the range of 45 mm.
15 ¦ The motor 24 is provided within the drum holder 41.
D.C. motors such as an inner rotor motor, outer rotor motor, a : I cup motor, Hall element motor, print motor, and brushless ¦ motor, may be used as the motor 24. The motor 24 comprises a ¦ rotor (armature) 62 accommodated within a motor casing 61, a ¦ field magnet 63, a commutator 64, a brush 65, and a rotary ~ shaft 66 mounted with the rotor 62. The rotary shaft 66 i9 ¦ axially supported by bearings 67 and 68 which are mounted on ¦ the motor casing 61, and the upper end of the rotary shaft 66 Il is em~eddedly fixed to the drum holder 41. Accordingly, the drum holder 41 is rotated with the rotary sha~t 66.
¦ A gear 69 is fixed to the lower end of the rotary ¦ shaft 66. The rotary shaft 66 ro~ates a shaft 74, through gears 69 and 70, a shaft 71, and gears 72 and 73. The above ¦ gears 69, 70, 72, and 73 constitute a speed reduction mechani~m ~ 84. The shaft 74 rotates an output shaft 76 through an I 1, Il .
! I I
lZC~4210 , 1 electromagnetic clutch 75. A belt is stretched across between the output shaft 76 and a pulley 77 which ~s provided on the lower end of the feed screw 2S. .
. A pickup head 78 of a frequency generator is provided at a position opposing the gear 69, and an output signal generated by the rotation of the gear 69 i~ obtained through a terminal 79. This output signal is used for rotational control. A driving voltage from a terminal 80 is supplied to the brush 65 of the motor 24, and a driving vol~age from a terminal 81 is supplied to the electromagnetic clutch 75. In addition, a recording signal is supplied to the magnetic head 46 from a terminal 82, and a reproduced signal is obtained ~rom this magnetic head 46.
When the driving voltage from the terminal 80 is ~15 supplied to the brush 65 to energize the motor 24, the rotary shaft 66 rotates, and the magnetic drum 30 rotates unitarily ¦ with the drum holder 41 at a rotational speed of 60 rps ~3600 ¦ rpm). The recording and/or reproduction with respect to the ¦ magnetic surface 31 i8 carried out by the magnetic head 46.
¦ Further, when the electromagnetic clutch 75 is activated by ¦ supplying the driving voltage from the terminal 81 thereto, the ¦ rotational speed of the rotary shaft 66 is reduced to 1/1000 ¦ the original speed by the above speed reduction mechanism, and ¦ the feed screw 25 is rotated by way of the belt 26. The ¦ magnetic head device 28 i5 thus moved upwards or downwards unitarily with the feed n~t 27, due to the rotation of the feed ; screw ~5. The speed reducing rat~o of the speed reduction ¦ mechanism 84, the rotation transmitting ratio with respect to ¦ the pulley 77, the screw pitch of the feed screw 25, and the like, are set so that the magnetic head 46 is fed by one track ~ 2~4Z10 1 ¦I pitch for one revolution of the magnetic drum 30, When continuously recording and reproducing moving ¦ pictures, the feed screw 25 is rotated continuously if the l electromagnetic clutch 75 is operated continuously, and the ¦ magnetic head 46 is accordingly moved continuously. Hence, at ¦ this point, the video signal i~ continuously recorded onto or reproduced from a spiral track on the magnetic surface 31 of the magnetic drum 30. In addition, when carrying out a still-pict~re-frame record~ng or reproduction, the above ¦ electromagnetic clutch 75 i5 activated intermittently. If the construction is such that the recording is carried out during the de-activated state of the electromagnetic clutch 7S, concentric track~ are formed on the magnetic surface 31, and l the spiral track is formed on the magnetic surface 31 if the ¦ construction is such that the recording is carried out during i the activated state of the electromagnetic clutch 75.
Limit switches 83a and 83b which make contact with the feed nut 27, are provided on the feed screw 25 so as to limit the feeding range limit of the magnetic head device 28.
i When the magnetic head device 28 is fed upwards from a ~ower position while carrying out recording or reproduction and ¦ reaches an upper limit position of the feeding range, the limit ¦ switch 83b i8 operated by the feed nut 27, and the magnetic ¦ head device 28 is returned to the lower position. The downward ¦ feeding of the magnetic head device 28 is stopped when the ¦limit switch 83a is operated by the feed nut 27.
¦If there is a possibility of leakage magnetic field ¦from the field magnet 63 to the magnetic drum 30 by using the lmotor shown in FIG.7 having the fleld magnet 63 as the motor 24 soft-iron and the like may be used for the motor casing 61 I- 22 _ ~/
1 ~ and/or the drum holder 41 to block the magnetic field.
However, according to the experimental results obtained by the present inventor for a trial manufacture, no problems were ~ observed from the practical polnt of ~iew even if a non-~ magnetic aluminum was used for the motor casing 61 and the drum holder 41.
¦ As an embodiment of a manufacturing method of the magnetic drum 30, aluminum or plastic is ~olded and the center axial line of the hollow part assumes the center line of 1 rotation to abrasively finish the outer peripheral surface with h~gh accuracy to form a magnetic drum base. A thin magnet$c layer of metal, alloy, ox~de, permalloy, amorphous, and the like is deposited onto the outer peripheral sur~ace of the magnetic drum base by vacuum deposition, and the magnetic surface 31 is formed by ion-plating, sputtering, electro-plating, or electroless plating.
When the magnetic drum 30 having a hollow l cylindrical-shape open on one end (lower end) is loaded into I the drive assembly 40, the construction is such that the drum ¦ driving mechanism comprising the motor 24, the drum holder 41, ~¦ and the like enter within the hollow part 30a of the magneti~
,¦ drum 30. For this reason, the size of the apparatus as a whole ¦ can be made considerably compact.
Next, description will be given with respect to an ¦ embodiment of the magnetic head device 28 by referring to FIG.8. A frame member 90 is formed by bending a magnetic materia~ into a substantially U-shape. Permanent magnets 91 and 92 are fixed to inner sides of arm portions of the frame member 90, and a U-shaped yoke 93 is fixed onto the base part ¦ of the frame member 90 between the permanent magnets 91 and 92.
lZ~4210 . ` , 1 ll A moving body 94 comprises a pair of coils 95 and 96 wound in a I rectangular form. Each of the coils 95 and 96 respectively are adjacent to a stiff support plate 97 and are fixed thereto. A
¦ leaf spring 98 made of phosphor bronze, ~or example, is provided across between tip ends of the arm portions of t~e frame member 90, in a state where both ends of the leaf spring ¦ 98 are respectively supported by rubber supports 99 and 100.
Pivot bearings 101 and 102 respectively having one end thereof fixed to the support plate 9 7, penetrate through a pair c~f ~ openings provided in the leaf spring 98. V-shaped grooves lOla and 102a are formed in the other end of the respective pivot bearings 101 and 102.
The magnetic head 46 is provided at the tip end of a 1~ cantilever 103. The cantilever 103 comprises two long and 1I narrow rods 104 and 105 fixed at the tip end thereof in a il V-shape. Conical-shaped pivots 104a and 105a of made of a hard material are provided at respective legs of the rods 104 and ,~ 105. A cubical rubber block 106 is provided at a central part ,i of the support plate 97, in a state where one surface thereof 'i is adhered to the support plate 97 and another surface thereof is adhered to the leaf spring 98.
A stylus pressure applying member 107 ~s made of rubber haYing a truncated conical-shape, and is fixed to a central position of the leaf spring 98. A connecting force ,, apply~ng member 108 made of rubber plate is fixed to the tip li end of the ~tylus pressure applying member 107. The rods 104 1l and 105 penetrate respective ends ,of the mem~er 108, and are ~, fixed to the member 108 at these penetrating points. In i; addition, the member 108 is forcibly bent in a substantially V-shape. Hence, the cantilever 103 receives a force ur~ing ., ~,,~,.
`` 1204Z10 ,1 ~
1 ~ displacement towards the moving body 94 due to a resilient ¦ restoration force exerted by the bent member 108. Moreover, ¦ the pivots 104a and 105a are in pressing contact with ¦ respective V-shaped grooves lOla and 102a. Further, a ¦ predetermined contacting pressure is applied to the magnetic ¦ drum 30 from the magnetic head 46, by a resilient force of the ¦ member 107 obtained through the member 108 and the cantilever 103.
The displacement of the movi~g body 94 due to a ¦ control signal current is faithfully transmitted to the cantilever 103, through the pivot bearings 101 and 102 and the pivots 104a and 105a. Accordingly, the magnetic head 46 is displaced in the direction of an arrow X and a tracking control ¦ operation is accurately performed. There is no need for the ~ above members 107 and 108 to be independent members, and these members 107 and 108 may be formed unitarily.
¦ The magnetic head device 28 is mounted onto the feed nut 27, 90 that the ~eeding direction of the magnetic head l device 28 coincides with a substantially longitudinal direction ¦ of the cantilever 103, that is, the direction of the arrow X.
The magnetic head 46 can be fed firmly because the mechanical strength of the cantilever 103 along its longitudinal direction is high.
l A metal piece 109 is attracted to the member 108.
¦ Although shown separately in FIG.8, an electromagnet 85 comprising a coil 87 wound around a core 86, is provided adjacent to the metal piece lO9, separately of the magnetic head device 28. The coil 87 is connected to the battery 17 l through a switch 88. The switch 88 is provided adjacent to the ¦ lid 23 of the apparatus 10, and is open while the lid 23 is I
1 ~Z~4Zl~ , 1 closed and closes when the lid 23 is opened. ~ence, if the lid 23 is opened in order to load or unload the cartridge 22 into or from the apparatus 10, the switch 88 closes and the electromagnet 85 is magnetized. Hence, the metal piece 109 is attracted to the electromagnet 85, an~ the magnetic head 46 is raised upwards along the direction of the arrow Z and away from ¦ the magnetic drum 30, to escape out o~ the cartridge 22.
Therefore, the loading and unloading of the cartr~dge 22 can be l carried out without disturbing the magnetic head 46.
¦ Next, description will be given with respect to an embodiment of a recording system and a reproducing system of the image picXup recording and/or reproducing apparatus 10 according to the present invention, by referring to a block ¦ system shown in FIG.9. In FIG.9, those parts which are the ¦ same a~ those corresponding parts in FIG~7 are designated by ¦ the same reference numerals.
A color video signal shown in FIG.101~) or ll~A) which is picked up by the solid-state image pickup element 14 and produced from the circuit including the printed circuit 1~, 1 is supplied to a recording signal producing circuit 112 and a ¦ chrominance signal processing circuit 113 from an output I terminal 110. Similarly, a synchronizing signal generated by ¦ the above circuit is supplied to a control circuit 114 through Il an output terminal 111. A control panel 115 is an operation panel including the operation switch 21 for setting the ¦ operation mode. An output of the control panel 115 is supplied to the control clrcuit 114. The control circuit 114 causes th~ I
motor 24 which drive~ the magnetic drum 30 to undergo 1-¦ synchronous rotation at the rotational speed of 3600 rpm as ¦ de~ rlbed before, through a drum ~ervo circuit 116. In I
lZ04Z10 1 addition, the control circuit 114 supplies a control signal ~n ; accordance with the operation mode to the electromagnetic ~ clutch 75 which causes a reduced rotational speed of 3. 6 rpm of ¦ the output shaft 76 by the speed reduction gear mechanism 83, through the terminal 81, to control the operation of the electromasnetic clutch 75.
The carrier chrominance signal within the above color video signal thus picked up, is frequency-converted into a low-band-converted carrier chrominance signal having a subcarrier frequency fsc ~629 kHz, for example) at the chrominance signal processing circuit 113. The resulting low-band-converted carrier chrominance signal is then supplied to the recording signal producing circuit 112. The recording signal producing circuit 112 separates the luminance signal within the above lS color video signal, and frequency-modulates the separated I ¦ luminance signal. The frequency-modulated luminance signal is ¦ subjected to frequency-division multiplexing with the low-band-¦ converted carrier chrominance signal from the chrominance signal processing circuit 113, and produces a recording I information signal. The frequency spectrum of this recording information signal is shown in FIG.12. In FIG.12, a band I
indicates the frequency-modulated luminance signal, and a band II indicates the frequency-converted carrier chrominance I signal. It is possible to also record an audio signal. In ¦ this case, an audio signal of the sound picked up by a microphone (not ~hown) of the apparatus 10 shown in FIG.l is frequency-modulated (the carrier frequency of the audio signal i8 fA) to occupy a band III ~hown in FIG.12.
¦ The above recording information signal is supplied to a switching c~rcuit 117. The recording information signal iB
~ ' 1~4;~10 1 passed through the switching circuit 117 only during even field I periods and blocked during odd field periods, for example, that is, the recording information signal is only passed through ~ during either one of the odd and even field periods, ~y a ¦ switching pulse shown in FIG.lOtC) having a 2-field period which is obtained from an input terminal 118. As a result, ¦ only the recording information ~ignal of the even field periods is passed from the switching circuit 117 during every other l field period (that is, a so-called field-skip is performed), ~ and supplied to a mixer 119. An output of a flip-flop (not ~. shown) triggered by a vertical synchronizing pul~e 6hown in . FIG.lO(B) which is separated from the input color video signal, ¦ may be used as the above switching pulse.
l A tracking signal generator 120 generates first and I second tracking control reference signals (hereinafter simply ¦ referred to as tracking signals) fpl and fp2 which exist within the band II of the above low-band-converted carrier chrominance signal as shown in FIG.12 and have mutually different . frequencies. A set of gate pulses respectively shown ln I FIGS.lO(D) and lO(E), each having a repetition frequency of 30 ~ z, which is a half of that of the abov~ switchlng pulse, of l, which the positive polarity period is a 1 field period in phase .I synchronism with the negative polarity period of the above l, switching pulse, and the relative phases of the two gate pulses ,I differ by 2-field period in time, are generated ~y a circuit ,¦ within the tracking signal generator 120. As a result, the first tracking signal fpl is supplied to the mixer 119 during 11 the positive polarity period of the gate pulse shown in j~
1 FIG.lO(D), and the second tracking signal fp2 is supplied to 30 1l the mixer 119 during the positive polarity period of the gate J
12(~42:10 1 ! pulse shown in FIG.lO(E).
In the present embodiment, in order to prevent beat ~ interference with respect to the recording information s$gnal ¦ in the magnetic recording and reproducing transmitting system ¦ and carry out the recording and reproduction at a suitable ¦ level with a high signal-to-noise (S/N) ratio, the tracking ¦ signals fpl and fp2 are generated in a form of tone burst existing only within intervals corresponding to horizontal l blanking periods avoiding the video period and the color burst 1 period of the input color video signal shown in FIG.ll~A~ as shown in FIGS.ll~C) and ll~E~ by the switching pulses shown in FIGS.ll(B) and ll~D). In addition, as clearly seen from FIGS.ll(A) through ll(E), the first and second tracking signals ~ fpl and fp2 are generated for every second lH (H indicate~ a ~ horizontal scanning period) for a 2H period, for reasons which l will be described hereinafter. Furthermore, as will be I described hereinafter, two kinds of tracking signals fpl and fp2 are recorded on adjacent tracks having therebetween one ' information signal recording track on the recording track ~ pattern, with l~ shift in an alternate manner.
Accordingly, only the first tracking signal fpl is ! produced from the mixer ll9 in a burst manner during a certain field (for example, odd field) period and a frequency-division `I multiplexed recorded signal FM ~Fel) of a succeeding field I ~even field) period is produced during that succeeding field period, as shown in FIG.lO(F). Further, during a succeeding odd field period, only the second tracking signal fp2 is produced in a burst manner, and dur~ng a succeeding even field l period, a recorded signal FM (Fe2) of that succeeding even field is produced. ~hus, a time-sequential multiplexed signal ll - 29 -I . ~ .
I~ 12~4210 I is obtained by similarly repeating the above described production of signals. The time-sequential multiplexed signal is amplified to a suitable level at a recording amplifier 121.
' The amplified signal from the recording amplifier 121 passes I through a switching circuit 122 which is connected to a terminal R by a recording mode signal from a recording mode terminal 123, and is supplied to the magnetic head 46 from the terminal 82. The signal hence supplied to the magnetic head 46 l is recorded on the spiral or concentric track formed on the magnetic surface 31 of the magnetic drum 30.
As described above, the first and second tracking signals fpl and fp2 exist within the band II of the low-band-converted carrier chrominance signal in the frequency spectrum.
ll However, timewise, these tracking signals fpl and fp2 are time-sequentially transmitted within a period different from ¦ the transmission period of the low-band- converted carrier chrominance signal. In addition, because the tracking signals fpl and fp2 are transmitted within the horizontal blanking l period avoiding the color burst signal period as shown in l FIGS.ll(A) through ll(E), the recording and reproduction can be carried out with high S/N ratio without beat interference therebetween.
Next, description will be given with respect to the l recording pattern on the magnetic drum 30. In the present ¦ embodiment, if the track width of the gap of the magnetic head 46 is set to 3.5 ~m and the track pitch is set to 2 ~ m, the time-sequential multiplexed signal shown in FIG.lO(F) is l recorded on the magnetic drum 30 with a track pattern shown in ¦ FIG.13. Because the magnetic drum 30 is driven to undergo ~ synchronous rotation at 3600 rpm under servo control, if a l ~ - 30 -l \
1 125)4210 1 1 position SP ls assumed to be the recording position of the vertical ~ynchronizing pulse, the vertical synchronizing pulses and the horizontal synchronizing pulses are recorded in a state aligned along the head feeding direction ~the direction of an 1 arrow A).
Each of the tracks tl, t2, t3, t4, --, t7, -- are formed by the magnetic head 46 for every one revolution of the magnetic drum 30. During t~e first revolution of the magnet~c l drum 30, the track tl is formed. In this track tl, the fir~t ¦ tracking signal fpl i8 recorded with a 2-field period from a position of the second horizontal ~lanking per~od after the l vertical ~ynchronizing pulse. The information signal recording ! track t2 is formed during the next one revolution of the l magnetic drum 30. The informatlon signal of the even field ~ period obtained from the above fiwitching circuit 117, is recorded in this track t2. Further, the track t3 1 5 formed during the next one revolution of the magnetic drum 30. In this track t3, the second tracking signal fp2 is recorded with l a 2-field period from a posit~on of the first horizontal ¦ blanking period after the vertical synchronizing pulse.
In the present embodiment, the track width indicated l by TW in FIG.13 is selected to a value larger than the track ; ¦ pitch indicated by TP, as ~escribed above. For this reason, . ¦ overlap recording i8 carried out between a certain track and a ¦ succeeding track which is recorded and formed following that ¦ certain track, by a length corresponding to the difference between the tracX width and the track pitch tl.5 ~ m in this case). A part of the track which i~ subjected to the overlap ¦ recording of another following track, is demagnetized at the 30 ¦ overlapping recording part. Similarly thereafter, the 12~42~0 1 ll recording position SP of the vertical synchronizing pulse assumes the starting point and the terminal point of the recording for every one revolution of the magnetic drum 30, and ¦ the tracking signal fpl or fp2 and the information signal are ¦ alternately recorded. Hence, on tracks formed on both sides of ¦ the information signal recording tracks t2, t4, t6, -¦ indicated by hatching in FIG.13, the first tracking signal fpl is recorded at positions indicated by solid lines on one track l and the second tracking signal fp2 is recorded at positions indicated by dotted lines on the other track. Accordingly, a track pattern is formed wherein the tracking signals fpl and fp2 are recorded overlapping over the information signal recording track by a length corresponding to the difference l between the track width TW and the track pitch TP. In ¦ addition, the recording positions of the first tracking signal fpl and the second tracking signal fp2 are shifted by 1~ as shown in FIG.13.
The principle of the tracking ~ontrol performed by ~ use of the first and second tracking signals fpl and fp2 is similar to that disclosed in a Canadian Patent No.1130456 although the recording medium is a disc in this ¦ patent.
¦ Description will now be given with respect to a ¦ reproducing system, by returning to FIG.9. During the ¦ reproduction, the switching circuit 122 is connected to a ¦ terminal P by a reproduction mode signal from the terminal 123.
The magnetic head 46 reproduces the information signal from recording tracks t2, t4, t6, ''- on the magnetic drum 30.
Because the track pitch TP is smaller than the track width TW, ¦ three kinds of signals, that is, the information signal and the lZ~Z10 Ij 1 ~ first and second tracking signals fpl and fp2 from the adjacent trac~s on both sides of the intended reproduc~ng track, are ¦ reproduced simultaneously. The reproduced signal passes ~ through the ~witching circuit 122 and is amplified t~ a ¦ suitable level at a preamplifier 124. The amplified signal is supplied to a H/2-delay circuit 125, a chrominance signal processing circuit 128, and an automatic gain control (AGC) ¦ circuit 132. The chrominance signal processiny circuit 128 l separates and filters the low-band-converted carrier ! chrominance signal from within the reproduced signal, and ¦ frequency-converts the low-band- converted carrier chro~inance signal back into its original band to obtain a reproduced carrier chrominance signal. This reproduced carrier l chrominance signal is supplied to a demodulating circuit 127 l through a H/2-delay circuit 129.
The de~odulating circuit 127 frequency-demodulates ¦ the frequency-modulated luminance signal from within the reproduced signal from the delay circuit 125. The demodulated l luminance signal is multiplexed with the reproduced carrier 20chrominance signal from the delay circuit 129. As a result, a ¦ color televLsion signal in accordance with the standard television system is produced. The output signal of the !~ demodulating circult 127 is fed to an output terminal 131, and ~ is also supplied to a synchronizing signal separating circuit 25¦ 137 and the control circuit 114. The vertical synchronizing ! pulse separated at the synchronizing signal separating circuit 137 is supplied to a switching pulge generator 138, and used as ¦ a reference when generating the switching pulse.
The delay circuits 125 and 129 repeat operations in 30which the input signal is delayed by H/2 for a certain field I ~, i i! lZ~4;~10 1 and not delayed for a field succeeding that certain field, according to respective control signals from terminals 126 and 130. Because the video signal which is recorded and reprod~ced ~ is a video signal of every second fields, that is, a video ¦ signal of either one of the odd or even fields, the above delay ¦ of H/2 for every second field is necessary to achieve an ¦ interlace.
The level deviation in the signal from the l preamplifier 124 due to causes other than the track shift, i~
¦ controlled to become constant at the AGC circuit 132. The output of the AGC circuit 132 is supplied to bandpass filters 133 and 134 wherein the first and second tracking signals fpl and fp2 within the reproduced signal are respectively l separated. Outputs of the above bandpass filters 133 and 134 lS ¦ are supplied to a switching circuit 135. The switching circuit 135 is switched by the switching pulse from the switching pulse ¦ generator 138, and alternately supplies the first and second ¦ tracking signals fpl and fp2 to input terminals 136a and 136b of a tracking servo circuit 136. The switching circuit 135 doe~ not perform switching duxing a slow-motion reproduction mode, and performs the switching only during the normal reproduction for every one revolution of the magnetic drum 30.
l, The tracking servo circuit 136 detects envelopes of the i tracking signals fpl and fp2, and produces a track~ng error ~25 ~ signal through a differential amplifier. The tracking error 1 signal i8 converted into a predetermined driving voltage, and ¦ supplied to the magnetic head d~vice 28. Accordingly, the ~agnetic head 46 is displaced along the track width direction of the recording track, and the tracking control i~ performed so that the trac~ing signals fpl and fp2 are constantly - 34 _ 1~4Z10 1reproduced with equal and the same constant reproducing level, ¦ that is, so that the le~el of the FN ~ignal within the ¦ reproduced information signal is maintained con~tantlY maximum.
l If a still-picture reproduction i~ to be carried out ¦ by repeatedly reproducing the same track, for example, the l Switchinq pulse i8 not generated from the switching pulse ¦ generator 138 (or the polarity of the ~witching pul~e is ¦ maintained to a constant level), and the tracking polarity is l constantly kept to the same polarity. When reproducing the l track t4 shown in FIG.13, for example, a track scanning locus of the magnetic head 46 is shifted towards the track t6 if the level of the first tracking signal fpl is greater than that of the second tracking s~gnal fp2. On the other hand, a track l scanning locus of the magnetic head 46 is shifted towards the ¦ track t2 if the level of the first tracking signal fpl is less than that of the second tracking signal fp2. Hence, the ¦ magnetic head 46 is displaced by a fine increment towards the l track t2 in the former case and towards the track t6 in the ; ¦ latter case, and the tracking control i8 performed ~o that the ¦ magnetic head 46 constantly scans over the center line of the l track t4.
¦However, when reproduction of the track tS is started from the pos~tion SP indicated in FIG.13 which is the terminal J
l position of reproduction of the track t4, the first tracking ,~
l signal fpl from the track t5 is reproduced with the maximum ¦
le~el, Thusr the magnetic head 46 is rapidly and t~
instantaneously displaced towards,the track t2, because the tracking polarity upon still-picture reproduction is maintained to the tracking polarity upon 8canning of the track t4. As a result, the magnetic head 4~ is drawn back so as to constantly . ~
lZ04Z10 1 I reproduce the track t4 even at discontinuous track parts where the recording posltion SP of the vertical synchronizing pulse ¦ is shifted, so that the reproducing levels of the tracking ¦ signals fpl and fp2 become balanced. Therefore, in this case, ¦ the still reproduction picture in terms of fields, can be ¦ performed by repeatedly reproducing only the track t4.
¦ Next, during normal reproduction, the magnetic head device 28 is fed contînuously along the axial di~ectlon of the magnetic drum 30 at a predetermined speed similar to that upon recording. Each track on the magne~ic drum 30 must ~e scanned and reproduced twice, because the so-called field-skip recording is carried out and the signal is recorded on the magnetic drum 30 for only every second fields as descri~ed above. In this case, after the magnetic head 46 scans over the track t2 shown in FIG.13 twice, for example, the magnetic head 46 must be rapidly moved to a position immediately after the position SP of the track t4 from a position of the track t2 ¦ immediately preceding the recording position SP of the vertical ¦ synchronizing signal. In this case, the polarity of the output 20 ¦ switching pulse of the switching pulse generator 138 is ¦ reversed so as to reverse the tracking polarity from the position SP. Accordingly, conversely as upon scanning of the track t2, the magnetic head 46 is displaced along the track ! width direction, towards the track t2 if the detected envelope of the tracking signal ~pl is larger than that of the tracking signal fp2, and towards the track t6 if the detected envelope of the tracking signal fpl is smaller than that of the tracking signal fp2. That is, tracking control is performed so that the magnetic head 46 scans and reproduces the track t4.
Thereafter, a symmetrical square wave ~n phase lZ~)4Z10 1 'I synchronism with the vertical synchronizing pul~e and having a 4-fleld period, is similarly generated by the switching pulse generator 138 and supplied to the switch~ng circuit 135.
~ Accordingly, the magnetic head 46 repeatedly reproduces each of 1 the information signal recording tracks twice, to obtain the normal reproduction picture.
FI~.14(A) shows an input reproduced signal waveform to the prea~plifier 124 during the above normal reproduction.
~ Signal waveform in fields Fel', Fe2', and Fe3' respectively ~ indicate signal waveforms obtained when the signals in the fields Fel, Fe2, and Fe3 are reproduced for the second time.
Moreover, during this normal reproduction, the tracking signal fpl shown in FIG.14(B) is obtained from the reproduced signal l at the bandpas~ filter 133, and the tracking signal fp2 shown ~ in FIG.14~C) is obtained from the reproduced signal at the bandpass filter 134. FIG.14(D) show~ the output switching l pulse of the switching pulse generator 138 durlng the normal ; I reproduction. Furthermore, FIGS.14(E) and 14(F) respectively I show input tracking signals to the input terminals 136a and 1 136b of the tracking servo circuit 136.
In the above embodiment, the video signal and the tracking signals are alternately recorded on each track on the magnetic drum 30 by the magnetic head 46. Hence, the so-called ¦ field-s~ip of every other field (only the evcn fields are l recorded, for example) is carried out upon recording with ¦ respect to the video signal. For this reason, if a microphone ¦ is provided in the apparatus 10 and an attempt is made to ¦ record the audlo signal picked up by the microphone together ¦ with the video signal by inserting the audio fiignal into the ¦ band III in FIG.12, the audio information will be missing for ~4210 1 ll the every other field by the above fiel~-skip recording.
Accordingly, in order to continuously record all fields of the video signal and continuously record the audio signal without missing the audio signal, two magnetic head devices 28 are provided separated from each other. The feeding range is limited so that one magnetic head device carries out recording and/or reproduction of an upper hal~ of the magnetic drum 30, and the other magnetic head device carr~es out l recording andJor reproduction of a lower half of the magnetic ¦ drum 30. Further, measures are taken so that one magnetic head records the tracking signals while the other magnetic head records the information signal comprising the video signal of l the odd fields, for example, and the audio signal, and the i above one magnetic head records the information signal lS ¦ comprising the video signal of the even fields and the audio ! signal while the above other magnetic head records the tracking signals. These operations are repeated thereafter. As a result, the video signal and the audio signal can be recorded l continuously, ~y alternately recording the information signal 1 and the tracking signals by the two magnetic heads.
In the above described embodiment~ the tracking signals fpl and fp2 are alternately recorded in succession, but ¦ the tracking signals may be recorded in a state multiplexed ¦ with the information signal, or example. Further, the track ¦ width and the ~uard band between the tracks may be made larger ¦ than in the above em~odiment, to omit the electronic tracking ¦ control circuit. In this case~ the construction of the ¦ apparatus 10 is simplified and the cost of the apparatus is ¦ reduced, although the recording capacity is reduced.
~ ~he window 37 on the case 36 o~ the cartridge 22 can 12t:~42~L0 1 ~ be made to close in the state where the cartridge 22 is not loaded into the drive ~ssem~ly 40 of the apparatus lO, and open when the cartridge 22 is loaded into the apparatus lO.
I In addition, in the above embodiment, the case 36 is S ¦ in a state loaded within the drive assembly 40 together with the magnetic drum 30, even in the state where the cartridge 22 is loaded within the drive assembly 40. ~owever, the construction is not limited to this construction. That is, the construction may be such that the magnetic drum iB accommodated 10within the case in the state where the cartridge is not loaded into the drive assembly, and the case is disengaged from the magnetic drum after the cartridge is loaded into the drive I assembly so that only the case is withdrawn leaving the ; ¦ magnetic drum w~thin the drive a~sembly. In this case, when ¦ the magnetic drum is to be retrieved from the apparatus lO, the case is inserted within the drive assembly to connect the case ¦ with the magnetic drum. Thereafter, the case and the magnetic ¦ drum is unitarily retrieved as the cartridge.
¦ Further, it is not essential to provide the mechanism ¦ for swin~ing the head upon loading and unloading of the cartridge 22. In relation with the cartridge loading mechanism, the magnetic head may be kept stationary (but mounted by way of a suitable resilient member) during the ~ loading and unloading of the cartridge 22, and the cartridge ¦ may be loaded and unloaded in an inclined state to avoid disturbing the magnetic head.
l In order to form the magnetic surface 31 of the above ¦ magnetic drum 30 into a perfect cylindrical-shape, the outer l peripheral surface of the main body of the magnetic drum 30 is ¦ machined to a perfect cylindrical-shape, and the surface is 12~4Zl~
1 ll subjected to precision lapping. The magnetic surface 31 is formed by applying the magnetic layer onto the surface thus formed by lapping, as described above.
Instead of forming the above magnetic surface 31 by ¦ the formation of the magnetic layer, a magnetic surface 141 can be formed on a magnetic drum 140 as shown in FIG.15. Thi3 magnetic surface 141 is formed by ~rapping a wide magnetic tape 142 around the main body of the magnetic drum in a spiral manner. In addition, although illustration thereo~ is omitted, a flexible plastic film (polyethylene terephthalate film~ for example) applied with the magnetic layer may be be formed into a cylindrical-shape, to obtain the magnetic drum by adhering both end~ of the plastic film.
The magnetic drum with such a machined and lapped body has an advantage of having a perfectly straight cylinder so that the scanning speed of the magnetic head with respect to the magnetic drum can be ideally constant as the diameter of the drum is constant throughout the full recording and/or reproducing range. ~owever, because of the complex manufacturing process of machining and lapping, the ,¦ manufacturing cost for such magnetic drums would be very 'I expensive. This suggests that such machined and lapped body I magnetic drum would only be suitable for industrial and '~ institutional applications where high performance ¦ characteristics are demanded, and not for consumer use.
And, in this regard, manufacturing such perfectly ¦ straight drums by plastic molding for cost saving purpose, 18 not praatical because the molded piece will not ~e removed from l the mold even if attempted.
The magnetic drum using the magnetic tape or the .
~l l l, ~2~4210 1 ~ magnetic fil~ can be manufactured at low co~t, and it i8 ¦ possible to mass produce ~uch a magnetic drum. However, there ¦ is a problem in that dropout i~ introduced in the recording and ¦ reproducing signal when the magnetic head scans over the ¦ boundary of the magnetic tape or the magnetic film which are ¦ adhered together.
Thu~, description will be given with respect to another embodiment of a recording medium, in which the above l problem ha~ been overcome.
10 1 A third embodiment of a recording medium is shown in FIGS.16 and 17. A magnetic drum 150 comprise~ a main drum body 151 molded from plastic having its outer peripheral surface made to a mirror-like finish, and a magnetic layer 152 applied I and fonmcd on the outer peripheral surface of the main drum body 151. ~he main drum body 151 has an outer form of a right I I circular truncated conical-shape obtained by cutting a right ~ circular cone along a plane parallel to the bottom surface ¦ thereof. The main drum body 151 is a hollow thin plastlc l molded piece, comprising a hollow part 151a. An opening 153 is ¦ prov~ded at the lower end of the main drum body 151, and a hole ¦ 155 is provided at the center of an upper end surface part 154.
A connecting part 156 made of a ferromagnetic material such as ¦ soft iron, for example, is embeddedly provided at the upper end ¦ surface part 154 in a state exposed to the lower surface of the ¦ upper end surface part 154. A hole 157 used as a mark part i6 ¦ formed at the lower ena of the ma~n drum body 151. This mark part may be provided at a position~ in the vicinity of the upper end of the main dru~ body 151.
If the imaginary vertex ~ngle of the r~ght circular conical-shaped main drum body 151 is assumed to be 2~, thi~
1~2~42:10 1 ~ angle 2~ is actually in the range of 1 to 4 although the ¦ angle 2~ is shown magnified in the f1gures as if this angle is I a larger angle. The main drum body 151 assume5 the right ¦ circular conical-shape in order to facilitate the molded main ~ drum body removing from the mold when this main drum body 151 ¦ is molded ~rom plastic, as will be described hereinafter-A molding apparatus 160 shown in FIG.18 i~ used~ for example, when molding the maln drum body from plasti~- The moldin~ apparatus 160 compr~se~ a convex mold die 161 and a concave mold die 162 hav~ng an in~ecting hole 163. The outer peripheral surface of the dl~ 161 and the inner peripheral surface of the die 162 respectively have the shape of a right circular cone having an imaginary vertex angle 23. First, in a state where the die 162 i8 separated from the die 161, a center hole of the connecting member 156 is fit over a central projection 164 of the die 161. Next, the die 162 and the die 161 are assembled in a state shown in FIG.18. Melted synthetic resin is injected into a gap 165 between the dies 161 and 162 through the injecting hole 163, in the state shown in FIG.18.
Thereafter, the dies 161 and 162 are cooled before these dies 161 and 162 are separated. A~ a result, the main drum body 151 molded from plastic, in which the connecting member 156 is embeddedly fixed thereto, is obtained. When removing the l molded main drum body 151 from the dies 161 and 162, the molded main drum body 151 can be removed with ease because the taper o~ the vertex angle 2~ is provided.
If the above vertex anglç 2~ is large, the diameter of the magnetic surface will differ a3 the magnetic head travels. As a result, the relative linear speed between the magnetic drum and the magnetic head will vary. Accordingly, it . 1~
lZ04Z10 1 is desirable for the vertex angle 2~ to assume a small angle, and the vertex angle 2~ is selected to a minimum value within a range in which the plastic molding is possible.
In order to apply and form the magneti~ layer on the outer peripheral surface of the main drum body 151 without subjecting t~e surface of the main drum body 151 to lapping process, the outer peripheral surface of the molded main drum body 151 must already be of a mirror-like fini~h. For this reason, the inner peripheral ~urface of the dle 162 must be of a mirror-like finish. For example, an amorphous material (silica glass, for example) having a mirror-like finish such that the surface roughness i8 in the range of 0.01 ~m, for example, by subjecting the amorphous material to optical polishing process, is used for the inner peripheral surface of ~15 the die 162.
A resin such as polycarbonate, acrylonitrile, butadiene, styrene copolymer resin (ABS), and acrylic resin which are superior in terms of heat-resistance, shock resistance, stiffness, and surface hardness, or a resin which is suited for molding process, is used for the synthetic resin material for the above molding.
The surface roughness of the outer peripheral surface of the molded main dxum body 151 is in the range of 0.01 ~ m, l and the magnetic layer is applied and formed on the outer ¦ peripheral surface by deposition, sputtering, electroles~ ¦
¦ plating, and the like. The magnetic drum 150 is completed by ¦ providing the hole 157 which act~ as the mark part, at a l predetermined posi~ion in the main drum body 151. As an 1 ~1 ¦ embodiment of a method of applying and form~ng the magnetic la er, there i~ a method in which a thin layer o~ cobalt, I
I . !
lZ~)4Z10 1~ 1 1 ¦ nickel, or phosphor alloy, for example, of a thickness in the ¦ range of approximately 0.1 ~m to 0.2 ~m is applied to the outer ¦ peripheral surface of th~ main drum body 151 by eletroless ¦ plating, and a protective layer of SiO2 having a thickness of ¦ 0.01 ~m is applied thereon.
In an embodiment of practical dimensions of the main drum body 151, the diameter of the upper end surface part 154 is 2S mm~ the diameter of the lower end part is 27 mm~ the I length of the generatr~x is 54 mm~ the vertex angle 2~ is 2~
¦ and the thickness of the peripheral side wall is 1.5 mm. In this example of the dimensions of the main drum body 151, the circumferential difference between the lower end part and the ¦ upper end surface part of the main drum body is approximately ¦ 7%. Accordingly, there approximately is a 7% difference in the ¦ relative linear speed between the ~agnetic head and the ¦ magnetic surface 152, at the lower end part and the upper end ¦ surface part of the main drum body. However, even if there is ¦ a difference in the relative linear speed to this extent, no ¦ problems are introduced ~n the actual magnetic recording and ¦ reproduclng characteristics from the practical point of view.
¦ A state where the magnetic drum 150 is loaded into a ¦ drive assembly 17~, is shown in FIG.19. In the drive assembly 170, a motor 171 is a coreless motor and is supported on a ¦ support 173 which is provided on a base 173. The motor 171 1 constructed so that a coil 175 rotates with respect to a fixed magnet 174. A rotary shaft 177 is supported by bearings 176a ¦ and 176b, ana rotates together w~th the coil 175. A rotary ¦ plate 178 is f~xed to the upper end part of the rotary shaft 177. Further, a ring-shaped permanent magnet 179 is provided on the upper surface of the rotary plate 178.
_ 44 _ ~Z~4Z10 1 The magnetic drum 150 i8 loaded into the drive assembly 170 from above, so that the motor 171 relatively enters within the hollow part 151a of the magnetic drum 150.
In addition, the upper end part of the rotary shaft 177 ¦fitted into the hole 155. When the upper end surface part 154 ¦ of the magnetic drum 150 is placed onto the rotary plate 178, ¦ the connecting member 156 embeddedly provided in the upper end ¦ surface part 154 ~s attracted by the permanent magnet 179 of ¦ the rotary plate 178, and the connecting member 156 and the ¦ permanent magnet 179 connect unitarily. Hence, when the motor ¦ 171 is rotated by supplying a voltage through a lead wire 182, the magnetic drum 150 is rotated unitarily with the rotary ¦ plate 178.
¦ A light emitting element 180 and a photosensitive 1 element 181 are respectively provided on the base 172 and the support 173, at height positions opposing the mark part 157 of the magnetic drum 150. As the magnetic drum 150 rotates, the ¦ photosensitive element 181 receives the light from the light-¦ emitting element 180 every time the mark part 157 passes ~0 ¦ between the photosensitive element 181 and the light-emitting ; ¦ element 180, and produces a signal indicating the rotat~onal ¦ phase of the magnetic drum 150. The recording and/or ¦ reproducing apparatus can constantly carry out the recording ¦ and/or reproduction with a constant phase relationship by using ¦ the above rotational phase signal, regardless of the phase ¦ relationship of the magnetic drum 150 with respect to the ¦ magne~ic head, with which the magnetic drum 150 is loaded into ¦ the drive assembly 170. Ac~ordingly, 1~ is possible to carry ¦ out the recording andlor reproduction so that the vertical ¦ synchronizing signal positions for each field are aligned on . ~
12~42~0 1 the genera~rix of the magnetic drum 150.
l A second embodiment of a magnetic drum cartridge in ¦ which a magnetic drum i8 accommodated within a case, is shown ¦ in FIGS.20 and 21. A magnetic drum cartridge 190 comprises a I magnetic drum 191 and a case 192. The magnetic drum 191 comprises a main drum body 193 and a magnetic layer 152 which i8 applied and formed on the outer peripheral surface of the ¦ main drum body 193. SimilarlY as in the case of the magnetic i drum 150, the hole 155 is provided on the upper end surface 1 part of the main drum body 193, and the connectlng member 156 ¦ is also embeddedly formsd in the upper end surface part. A
¦ plurality of or a r~ng~shaped projection 194 is unitarily ¦ formed on the outer peripheral edge part at the lower end of ¦ the main drum ~ody 193 The case 192 comprises an external wall part 195 of a hollow cylindrical-shape which is open at the lower end thereof, and an inner wall part 196 which engages with the i lower end part of the external wall part 195 being coaxially ~ assembled inside a hollow part 193a of the main drum body 193.
1 A lower half of the magnetic drum 191 resides within a gap ¦ between the outer and inner wall parts 195 and 196, separated ¦ from these outer and inner wall part~ 195 and 196. Upon assembly, the upper end surface part of the magnetlc drum 191 is inserted into the outer wall part 195 of the case 192 up to the tip end thereof, and the inner wall part 196 is inserted into the hollow part 193a thereafter, to engage the inner wall part 196 to the outer wall part 195 at an engaging part 197. A
plurality of or a ring-shaped projection 204 is formed on the inner peripheral surface of the outer wall part 195 of the case ¦ 192. The magnetic drum 191 ~s restricted of its movement in 12(-4210 i .', the horizontal direction within the outer wall part 195 by the projectiong 194 and ~04, and the magnetic layer is prevented from being damaged due to contact between the inner periphera surface of the outer wall part 195. The outer and inner wall parts 195 and 196 are molded from plastic, for example. Light transmitting holes 198 and 199 are respectively provided at the lower end parts of the outer and inner wall parts 195 and 196, at positions opposing the hole 157 provided at the lower end part of the magnetic drum 190 as a mark part. ;~
10 l A window 200 for permltting the magnetic head to make t, contact with the magnetic layer of the magnetic drum 191, is provided on the outer wall part 195 of the case along the generatrix direction thereof. A guide projection 201 is formed at the outer peripheral part of the window 200. The guiding pro~ection 201 fits into a groove (not shown) provided on the drive assembly when the cartridge 190 i~ loaded into the drive ~;
assembly of the recording and/or reproducing apparatus~ to J
restrict the facing direction of the case to a predetermined ~}
direction. Accordingly, the window 200 of the case 192 always opposes the magnetic head in the loaded state. A guiding projection 202 comprising a hole 203, is provided at a predetermined position on the inner peripheral surface of the inner wall part 196.
A drive assembly loaded with the above magnetic drum cartridge 190, i8 shown ln FIG.22. In FIG.22, those parts which are the same as those corresponding parts in FIGS.7 and 19 are designated by the same reference numerals, and their ¦
description will be omitted. ¦-A cartridge holder 211 which externally covers amotor similar to the motor 171 shown in FIG.1~, is fixed to a ,l 12~42~V
1 base. The cartr~dge 190 1~ loaded into a drive assembly 210, 50 that the holder 211 relatively enters withln the cartridge 190 from the lower end opening of the cartridge 190. In thi8 l state, the guide projection 201 engages with the groove in the 1 drive assembly, and further, guiding pro~ection 202 engages with and i8 guided by a guiding groove 212 of the holder 211, to restrict the loading direction of the ca~e 192. When the cartridge 190 is loaded unto a final position, a projection provided at the guide groove Z12 engages with the hole 203 in the guiding projection 202 of the inner wall part 196, and the cartridge 190 is accordingly positioned. A ball applied with an urging force of a spring, for example, may be used instead of the above projection 213.
The feed screw 25 i9 rotated by a motor 214 which is a motor independently provided in addition to the motor 171 for driving the magnetic drum. The feed n~t 27 is guided by a guide bar 215 so as not to rotate, and moves linearly as the feed screw 25 rotates. The feed screw 25 and the guide bar 215 are provided obliquely with respect to the rotary shaft 177 of the motor 171 so a~ to form an angle ~ with the rotary shaft 177, so that the feed screw 25 and the guide bar 215 become parallel to the magnetic surface of the magnetic drum.
FIG.23 shows a view in vertical cross section of a Y
state where the cartridge 190 shown in FIGS.20 and 21 ~ 8 loaded into the drive assembly 210 shown in FIG.22. By the guidance and po~itioning provided by the above gu~ding projection 201 and the groove, and the guiding projection 202 and the guiding ~5 groove 212, the window 200 assumes a position oppo~ing the -~
magnetic head 46. In addition t the holes 198 and 199 ~n the ,`
outer and inner wall parts 195 and 196 of the cartridge 190, - 48 - ~`
~Z~4210 ll 1 1 are respectively posi~ioned opposing the respective light-emitting element 180 and the photosensitive element 181.
The rotational phase detectin~ means is not limited to the comblnation of the hole 157, the light-emitting element 180, and the photosensitive element 181. For example, as shown in FIG.24, a permanent magnet piece 220 may be embeddedly provided at the position of the hole 157 acting as the mark part, and a pickup head 221 may be provide~ at a position opposlng the permanent magnet piece 220. Further, rotational phase detecting means which detects the rotational phase accordlng to variation in electrostatic capacitance may be used.
Another embodiment of the connection between the rotary plate ixed to the rotary shaft of the motor and the upper end surface part of the magnetic drum, is shown in FIG.25. In this embodiment, a ring-shaped connecting plate 230 made of soft iron, is embeddedly provided in the lower surface of the upper end surface part 154 of the magnetic drum 150. A
projection 231 which ~its into the hole 155 ln the magnetic drum 150, ~ 8 unltarily provided at the center of the rotary plate 178. A ring 232 made of a ferromagnetic material i8 provided on the outer peripheral surface of the rotary plate l 178, for shieldin~ the leakage magnetic flux from the permanent ¦ magnet 179. A depression is formed in the upper surface of the l rotary plate 178, excluding the outer peripheral edge part and the center projection 231, so that the magnetic drum 150 is supported by the outer peripheral edge part of the rotary plate 178.
Embodiments of the magnetlc head 46, are shown ~n ~ ¦FIGS.26 and 27. In a magnetic head 46a shown in FIG.26, a thin r ~ ` ~ 49 -~ 4210 I I layer 240 made of an alloy is sandwiched between polycrystal ferrite plates 241 and 242, to constitute a magnetic path. The tip end part of the thin alloy layer 240 is sandwiched between I ceramic plates 243 and 24~ having a high resistivity against frictional wear, and a gap 245 is formed at the center of the thin alloy layer 240 and the ceramic plates 243 and 244. Coils 246 and 247 are wound around parts in the vicinity of the tip l end parts of the respective ferrite plates 241 and 242. The I curvature of a curved concave surface 248 including the gap ~ 245, is slightly smaller than the minimum curvature of the magnetic drum (the maximum diameter part).
A magnetic head 46b shown in FIG.27 comprises a pair of head cores 250 and 251 made of single crystal ferrite.
~ Glass bondings 253 are adhered in the vicinity of a gap 252. A
curved concave surface 254 including the gap 252, is formed at the tip ends of the head cores 250 and 251.
lNext, description will be given with respect to I Iembodiments of a case which accommodates a magnetic drum and lconstitutes a cartridge, by referring to FIGS.28 through 31.
¦A case 260 shown in FIG.28 comprises the outer wall ¦ part 195 having a similar shape as that shown in FIGS.20 and ¦ 21, and a ring member 261 engaging with the open end of the ¦ outer wall part 195. The ring member 261 prevents the magnetic ; ¦ drum 191 from slipping out of the case 260, and also acts as a ¦ guide upon loading into the drive assembly.
¦ A case 270 shown in FIG.29A comprises a leaf spring ¦ 272 at the center of the ceiling surface of an upper plate part ¦ 271. The leaf spring 272 pushes a ball 273 agalnst the center ¦ top of the magnetic drum 191. In a non-operated state of the ~ cartridge, the magnetic drum 191 is pushed by the leaf spring I
42~0 I 1 272, and the lower end edge part of the magnetic drum 191 makes contact with the ring mem~er 261. Accordingly, undesirable ~ rotation and play is prevented during the non-operated state of ¦ the magnetic drum 191. Next, when the cartridge is loaded into I the drive assembly, the upper end part of the rotary shaft 177 of the motor engages with a depression provided at the center on the lower surface of the upper end surface part of the magnetic drum 191, as shown in FIG.29B. In addition, a rotary plate 275 fixed to the upper part of the rotary shaft 177 makes i contact with the ceiling surface of the upper end surface part of the magnetic drum, to lift the magnetic drum. Hence, the lower edge part of the magnetic drum 191 separates from the ring member 261, and assumes a state rotatable together with the rotary plate 275.
A hole 282 is provided at the center of an upper plate part 281, in a case 280 shown in FIG.30. When this cartridge i5 loaded into the drive assembly, the magnetic drum 191 is lifted by the rotary plate 275, and also pushed i downwards by a pushing member 283 comprising a ball 284. As a ¦ result, the ceiling surface of the upper end surface part of ¦ the magnetic drum 191 makes pressing contact with the rotary ¦ plate 275, to ensure fine transmission of the rotation. The ¦ pushing member 283 is provided on the lower surface of the lid ¦ 23 of the apparatus 10, for example.
~5 ¦ Still another embodiment of a drive assembly is shown ¦ in FIG.31. In each of the above embodiments, the magnetic drum ¦ is coupled to the upper part of the rotary shaft of the motor, by means such as the screw 44 and the nut 60, the magnet 179 of the rotary plate 178 and the connecting part 156, and the like.
~0 For this reason, if there is fluctuation in the axis of the ,, .~ :...
lZ04210 1 rotary shaft, the fluctuation at the lower end of the magnetic drum becomes amplified compared to the fluctuation at the upper part of the magnetic drum. ~he present embodiment hag eliminated this problem.
A bearing 290 is provided at the outer periphery of the motor sup~ort 173. A ring-shaped receiving member 291 i8 :~
provided at the outerlace of the bearing 290. When the magnetic drum 191 is loaded into the ~rive assembly, the ;
connecting part 156 is attracted by the permanent magnet 179 of the rotary plate 178, and the upper end surface part lS4 of the .
magnetic drum iR placed onto the rotary plate 178, the inner peripheral surface at the lower end part of the magnetic drum 191 closely fits over the the outer periphery of the receiving member 291. Hence, the magnetic drum 191 iB supported at two positions, that ~s, at the upper and lower end part~ thereof.
When the motor 171 is operated and the rotary shaft ~ I
177 rotates, the magnetic drum 191 is rotated by the rotary plate 178. In this state, the receiving member 291 which i9 .i~
axially supported by the bearlng 290 due to the friction ~etween the magnetic drum 191, is also rotated. Becau~e tha magnetic drum 191 is also received by the receiving member 291 in this state, fluctuation in the axis is hardly introduced even at the lower end part of thereof upon rotation. ~
l The receiving member 291 may be embeddedly provlded ¦ in the bearing 290. Moreover, the outerlace of the bearing 290 ~i~
itself may be used as the receiving member 291.
I Further embodiments of the magnetic drum is shown in J,~
¦ FIGS.32 and 33. In the above described e~bodiments, the hollow ¦ main magnetic drum body comprises the hollow part which has one ~7 end e~ and the other end closed by the upper end surface 12~4Z~Lo \
1 part. However, in the embodiments described hereinafter, both the upper and lower ends of the hollow main magnetic drum body ~;
I are open.
¦ In the embodiment shown in FIG.32, a magnetlc drum 5 ¦ 300 comprises a hollow and substantially cylindrical-shaped ¦ main body 301, and a magnetic surface 302 applied and formed on ¦ the cylindrical peripheral ~urface of the main body 301. The ¦ main body 301 compri~e~ a partitioning wall part 303 at a center part thereof. The hollow part within the main body 301 l is partitioned into hollow parts 304 and 305 respectively having opening~ 304a and 305a, by the partitioning wall part 303. 3,'~
The connecting me~ber 156 i9 embeddedly provided at l the lower surface of the wall part 303. When the magnetic drum ~ 300 is loaded into a drive a~sembly comprising the motor 171, the motor 171 relatively enters within the hollow part 305 from the opening 305a. The rotary shaft 177 fits in~o a center hole 306 in the wall part 303, and the magnet 179 attracts the I connecting me~ber 156. Thus, the wall part 303 rest~ on the ¦ rotary plate 178. In this state, a part of the motor 171 may be exposed outside the magnetic drum 300.
According to the present embodiment the magnetlc drum 300 is driven in rotat~on in a state where the center part l thereof along the longitudinal direction is supported. Thus, ¦ the fluctuation in the axi~ at the upper and lower ends of the magneti~ drum 300 due to fluctuation~ in the axes of the rotary shaft 177 and the rotary plate 178, becomes one-half the ~luctuation in the axi~ at the lower end part of a magnetic rum of a type which is rotationally driven at the upper end surface thereof as shown in F~GS.19, 23, and 24, for example.
. i Il ~2~4210 1 ¦ In the embodiment shown in FIG.33, a magnetic drum 310 comprises a hollow substant~ally cyl~ndrical-shaped main ¦ body 311 open on both the upper and lower ends thereof, and a ¦ magnetic surface 312 appl~ed and formed on the cylindrical ¦ peripheral surface of the main body 311. The main body 311 comprises tapered parts 313 and 314 at upper and lower ends on ¦ the inner peripheral surface thereof. When the magnetic drum 310 is loaded into a drive assembly comprising the motor 24, ¦ the lower end tapered part 313 rests on the tapered part 45 of ¦ the drum holder 41. Then, a holding plate 315 is placed onto ¦ the magnetic drum 310 in a state where the set screw 44 of the ¦ drum holder 41 is inserted through a hole 316 of the holding ¦ plate 315. In this state, a tapered part 317 of the holding ¦ part 315 fit~ along the upper end tapered part 314 of the ¦ magnetic drum 310. Next, the nut 60 i8 firmly screwed onto the ¦ set screw 44. As a result, the magnetic drum 310 becomes ¦ supported at two positions, that i8, at the upper position at ¦ the tapered part 45 of the drum holder 41 and the lower ¦ position at the tapered part 317 of the holding plate 315, and ¦ the magnetic drum 310 is accordingly driven by the motor 24 and ¦ rotated unitarily with the drum holder 41.
¦ ~ext, description will be given with respect to a second embodiment of an image pickup recording and/or ¦ reproducing apparatus according to the present invention, by ¦ re~erring to FIG.34. In FIG.34, those part~ which are the same ¦ as those corresponding parts in FIG.l are designated by the ¦ same reference numerals, and their description will be omitted.
¦ An image pickup recording andtor reproducing ¦ apparatus 320 has a construction substantially similar to the ¦ abov described apparatus 10, and a ma~or difference between - 5~ -lZU4210 1 the two apparatuseg 10 and 320 :Ls in that the apparatus 320 has ¦ a connector 321 which is connected to a connector 331 of an ¦ adapter 330 which will be described hereinafter. The connectors 321 and 331 constitute a connector part 322. A lid 323 for holding down the magnetic drum cartridge, has a spring ¦ 324 at a central part thereof, and ~s provided in a manner free ¦ to open and close~ The aforementioned switch 88 is provided at ¦ a position so that the switch 88 is closed and opened as ¦ described before by the opening and closing of the lid 323.
The adapter 330 has a plug 332 which is connected to a commercial power outlet, and an ON/OFF s~itch 334, a fast-backward switch 335, a fast-forward switch 336, a still -shift switch 337, and a play switch 338 are provided on a l manipulation panel 333. The adapter 330 comprises a ¦ reproducing circuit as will be described hereinafter. The adapter 330 is connected to a televiRion receiver 340 through a cord 339.
When using the apparatus 320 for image pickup l recording, the connectors 321 and 331 are not connected, and ¦ the apparatus 320 is used independently. On the other hand, when reproducing the picture just subjected to the image pickup recording or a magnetic drum which is already subjected to the image pickup recording, the connectors 321 and 331 are l connected to constitute the connector part 322 to connect the ¦ apparatus 320 to the adapter 330. In addition, ~he adapter 330 and the television receiver 340 are connected by the cord 339.
Then, the plug 332 is connected to the power source, and when predetermined operations described hereinaftex are carried out, the signal reproduced from the magnetic drum at the apparatus ¦ 320 i5 supplied to the televig~on receiver 340 through the '~ . ~
_ _ _ _ ~4Z10 1 adapter 330, and the reproduced signal is reproduced as a reproduced picture on the television receivex 340.
l A block system of a circuit of the above apparatus ¦ 320 ls shown in FIG.35A, and a bl~ck system of a circuit of the ¦ adapter ~30 is shown in FIG.35B. In FIGS.35A and 35B, those parts which are the same as those corresponding ~arts in FIG.9 are designated by the same reference numeralg, and their ¦ description will be omitted.
During the image pickup recording mode, the connectors 331 and 321 are not connected, and the apparatus 320 i8 used indepen~ently. A switch 351 of the apparatus 320 shown in FIG.35A, is connected to a contac~ R which ls connected to the battery 17. When the apparatus 320 i~ not used, a knob of the operation switch 21 i8 in the ~OFF~ positlon, and a switch 352 is connected to a contact a. Prior to starting the image pickup recording, the knob of the operation switch 21 is first slid to the "READY~ position. ~y this opsratlon, the switch 352 is switched over and connected to a contact b, and the ; voltage from the battery 17 is supplied to each clrcuit through the switches 351 and 352 and a terminal 353. A driving signal is supplied to a servo circuit 361 from a control circuit 354 including the switching pulse generator, and the motor 171 accordingly ~tarts rotating.
A composite synchronizing Eignal from the terminal 111 i9 supplied to a synchronizing signal separating circuit 358 wherein the horizontal synchronizing signal and the vertical synchronizing signal are separatad. The separated horizontal and vertical synchronizing signals are respectively supplied to the control circuit 354. The separated vertical synchronizing signal is also supplied to a servo circuit 359 1! ~2~42~0 ~
1 I and the servo circuit 361. The rotational phase detect ¦ output from the pickup head 221 is supplied to the servO ; , ¦ circ~it 361. Hence, the motor 171 rotates at a rotationa ¦ speea of 3600 rpm, in synchronism with the vert~cal ¦ synchronizing signal of the video signal.
The shutter button 19 is pushed and a shutter switch l9a is closed, in order to start the image pickup recording.
The shutter switch l9a remains closed while the shutter button l 19 iis being pushed, and a cont~nuously mov~ng picture i~
¦ recorded as will be described hereinafter. When the shutter switch l9a is closed, the control circuit 354 supplies the switching signal shown in FIG.lO(C) to the switching circuit 117. Thus, the ~witching circuit 117 passes the video signal l of the even fields, for example, for every other field.
¦ Further, the control circuit 354 suppl~es the switching s~gnals shown in FIGS.lO~D) and lO(E) to a switching circuit 362. The switching circuit 362 alternately passes the tracking signals fpl and fp2 from a tracking signal generator 355 for every l other field ~for every two fields), that is, passes one l tracking signal for every fourth field (for every four fields).
Accordingly, the recording information signal shown $n FIG.lOIF) is obtained from the mixer 119. This infor~ation signal i9 applied to the magnetic head 46, through the I recording amplifier 121 and the switch 122 connected to the ¦ terminal R.
During the interval in which the shutter switch l9a is closed, a driving signal is supplied to the servo circuit 'l~
359 from the control circuit 354, and the feed motor 214 i8 l thus rotated, The rotational phase of the motor 214 ~s detected by a known rotational phase detecting means 360 - 5~ -l . . .~ ~
comprising a permanent magnet provided on a rotary plate and a magnetic pickup head, for example. An output of this rotational phase detecting mean~ 360 is supplied to the servo circult 359. The motor 214 is a geared motor having a speed reduction gear mechanism, for example, and rotates the feed screw 25 by the rotational output of a reduced speed. In this case, the rotary body of the rotational phase detecting means 360 is rotated with a rotational output which is not reduced of the speed. As a result, the motor 214 rotate~ in synchronism with the vertical synchronizing signal from the synchronizing signal separating circuit 358. The magnetic head device 28 is fed towards the left side in FIG.35A, for example, due to the rotation of the motor 214, and the above information 6ignal is recorded onto the spiral track on the magnetic surface of the i I magnetic drum 191 by the magnetic head 46. In this state, the motor 214 is already started and ls rotating at a predetermined rotational speed.
While the shutter button 19 is being pushed, the I above operation is continuously performed, and the recording of I I the moving picture is continuously carried out although the recording is a field-skip recording. When the recording by the magnetic head 46 extends to one recording range limit position ¦ on the magnetic drum 191, the feed nut 27 pushes and activates l the limit switch 83b. The signal from the limit switch 83b is i supplied to the control circuit 354 through a terminal 356. As a result, th~ control circuit 354 stops producing and supplying the switching signals to the switching c~rcuits 117 and 362 so that the switching circuits 117 and 362 stops producing signals, and further, the control circuit 354 supplies a reverse polarity driving signal to the ~ervo circuit 359 to Il .
l;~U4210 1 l rotate the motor 214 in the reverse direction at a high rotational speed. The magnetic head device 28 is rapidly l returned towards the right side in FIG.35A due to the reverse I rotation of the motor 214. When the magnetlc head 46 iB
¦ returned to the other recording range limit position on the ¦ magnetic drum 191, the feed nut 27 pushes and activates the ¦ limit switch 83a. The signal from the limit switch 83a is supplied to the control circuit 354 through the terminal 356, ¦ and the the control circuit 35~ stops supplying the driving signal to the servo circuit 359. The motor 214 is hence stopped from rotating.
If the shutter button 19 is released from being pushed before the magnetic head reaches the above one recording range limit position, the driving signals from the control circuit 354 are stopped from being supplied to the servo l circuits 359 and 361, and the motors 171 and 214 are l accordingly stopped from rotating. When the shutter button 19 I is thereafter pushed for the second time, the magnetic head 46 l starts to carry out recording from that position.
ll In the abo~e embodiment, description was given with respect to the recording of moving picture, in order to simplify the explanation. However, if still pictures are to be recorded, a n STILL~ position is further provided on the I operation switch 21, so that the video signal of one field is recorded on one track turn of the magnetic drum 191 when the shutter button 19 is pushed.
As described above, during the reproducing mode in which the signal subjected to the image pickup recording i~
~ reproduced, the connector 331 of the adapter 330 is connected to the connector 321 to constitu~e the connector part 322. The ~ _ 59 _ ~42~
1 ~I cord 339 of the adapter 33Q is connected to the television f receiver 340. The plug 332 of the adapter 330 i8 plugged into a power source device 350 as shown in FIG.35B. The power ~ source device 350 is a device for reducing the voltage of the I commercial power source into a predetermined rated voltage and producin~ a DC voltage by rectifying and smoothing the reduced ¦ voltage. However, an arbitrary power source such as a battery ¦ power source of an automobile may be used as the power source device 350.
10~ The switch 351 shown in FIG.35A is mechanically switched over and connected to a contact P from the contact R
¦ by a connector pin, when the connector 331 is connected to the connector 321. As a result, the supply o~ power from the battery 17 i~ interrupted, and the voltage from the power 15source device 350 is supplied to each circuit through a connector terminal 322a and the terminal 353.
Upon starting of the reproduction, the ON/OFF switch 334 of the operation panel 333 of the adapter 330 shown in l FIG.35B is put into the ON state. An ON signal ~rom the ON/OFF
I switch 334 is then supplied to the control circuit 354 through a connector 322b. Thus, the control circuit 354 produces and supplies a switching signal to the sw~tch 122, to switch over and connect the switch 122 to the contact P from the contact R.
In addition, the control circuit 354 supplies a driving signal 11 to the servo circuit 361, to drive and rotate the motor 171.
If a normal reproduction is to be carried out, for ~xample, the play switch 338 is p~shed. Accordingly, a play ¦ signal is supplied to the control circuit 354, and the control l circuit 354 supplies a driving signal to the servo circuit 359 ¦ to rotate the motor ~14. The magnetic head device 28 ~s fed 12~4210 I l due to the rotation of the motor 214, and the signal reproduced from the magnetic drum 191 by the magnetic head 46 is supplied to the preamplifier 124 of the adapter 330, through the switch 122, a preamplifier 363, and a connector terminal 322h. The I composite video signal obtained from the demodulating circuit 127 is obtained through an output terminal 357, by similar ~ circuit and operation as those described in conjunction with ¦ the bloc]c system shown in FIG.9. The composite video signal ¦ thus obtained, is supplied to the television receiver 34~
0 through the cord 339, and the moving picture is accordingly reproduced on the screen of the television receiver 340. The delaying or non-delaying operations of the H/2-delay circuits 125 and 129 for every one field, are controlled by a control ~ signal from the control circuit 354 obtained through a 15 ~ connector terminal 322f.
Moreover, the vertical synchronizing signal from the ¦ synchronizing signal separating circuit 137 is supplied to the control circuit 354 and the servo circuit 361 through a ¦ connector terminal 322c, and used instead of the vertical 20 ¦ synchronizing signal from the synchronizing signal separating circuit 358 obtained upon recording mode. The output tracking control signal of the tracking servo circuit 136 is supplied to ¦ the tracking coil of the magnetic head device 28 through a l connector terminal 322g, and the tracking control is performed 25 ¦ so that the magnetic head 46 accurately scans over the information signal track. Furthermore, the output signal of the tracking servo circuit 136 is also supplied to the servo circuit 359 through a connector terminal 322e, to control the rotation of the motor 214. Because the recording is carried ~0 out with respect to the magnetic drum 191 according to the I
lZ04Z10 1 ¦ above field-skip system a~ described before in conjunction with ¦ the block system shown in FIG.9, each track must be reproduced ¦ twice~ Hence, a signal is supplied to the switching pul~e ¦ generator 138 from the control circuit 354, through a connector 5 ¦ terminal 322d, so that the polarity of the output switching ¦ pulse of the switching pulse generator 138 is reversed when the ¦ magnetic head 46 reaches the position SP shown in FIG.13.
The still-shift switch 337 is pushed to carry out the l still-picture reproduction. When the still-shift switch 337 is 1 pushed, a still signal is supplied to the control circuit 3~4.
In this state, the motor 171 remains to rota~e, but the motor 214 is stopped from rotating, and the same track is repeatedly reproduced by the magnetic head 46. As a result, the l still-picture reproduction is carried out. In the above state, a stop signal is applied to the switching pulse generator 138 ~ rom the control circuit 354, through the connector terminal ¦ 322d, so that the switching circuit 135 does not perform a switching operation.
~ If the still-picture reproduction is to be carried ¦ out with respect to the next field, the still-shift switch 337 I is pushed for the second time. When the still-shift switch 337 ¦ is pushed for the second time~ a signal i8 again supplied to the control circuit 354 from the switch 337, and the motor 214 ¦ is rotated. As a result, the magnetic head device 28 is fed by ¦ one track, and still-picture reproduction is carried out with I respect to the next track by the magnetic head 46.
If the magnetic head 46- is to be rapidly fed to a predetermined track position by advancing or moving back the magnetic head 46 so as to reproduce the picture of a desired content, the fast-forward switch 336 or the fast-backward 12~42~0 1ll switch 335 is pushed. When the swltch ~36 or 335 is pushed, I the control circuit 354 supplies a fast forward or rewind ¦ signal to the servo circuit 359, and the motor 214 is ¦ accordingly rotated at a high speed in the forward or reverse 5~ direction. While the switch 336 or 335 is being pushed, the magnetic head 46 advanc~s or moves back at a high speed, and ¦ the search for the position of the above desired picture I content can be completed ~uickly. The play switch 338 or the still-shift switch 337 is pushed after the above search is ¦ completed, to carry out the normal reproduction or the still-picture reproduction.
The information signal which is recorded onto and reproduced from the magnetic drum is not limited to the video l signal, and may be a pulse code modulated (PCM) audio signal.
¦ In addition, the above recording medium may also be used as a ll terminal memory of a computer in place of the existing floppy I disc.
Further, the present invention i6 not limited to , these e~bodiments, but various variations and modifications may ' be made without departing from the scope of the present l~ invention.
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