Note: Descriptions are shown in the official language in which they were submitted.
s
IMAGE ST(:I~AGE AND
~RETRIlEVAL APPAlE~ATUS
E~ackgr~und of the In~rent~o~
This invention r~lates gcnerally to all ~age storage
and retrieval apparatus and more pa~icularly relates to a~
S apparatus ~or storing m~re than 2000 still color video images
on a storage medium, such as a magnetic disk, a~d r~trieving
~e images for display and lpr~cessillg.
~rre~t digital record~ng with its atte~da~t cnst has
prevented high density storage of ~till color video images ~d
high speed random acce3s wil:h ~rasability. The problem
VVAth stora~e of color images i~ digital form is the
tremendous ~nou~t of storage ca~ity requi~ed, typically
500+ ~ilobyte~ of storage pet ~age. (~tical discs9 while
pro~iding high deDsity storage, a~ ot erasable at r~ able
cos~.
I~ video recordi~g, ~he lulminance and eolor
component~, of a video signal a~ ei~er recorded toge~er on
a si~gle magnetic tra~k or are recorded separa~ely on two or
more tracks. Predictably, ther~ are adval~tages alld
drawbacks to each app~oach. Sil~gle track recording
requires less recording media spa~e and ~ereby illcreases the
llumber of images ~a~ caII be placed on a giveII magnetic
media. Recording the video sign~l components on two or
more tracks usually improves ~e image quality, but severely
~;
complicates ~e appara~s and reduces ~e storage capa~ity of
a given media by one half or more.
Early Yideo disk recorders for ~plays were
pio~eered by ~mpex and othe~s in the 1960's and used bo~
S rigid and floppy disk mag~etic media for storage of images.
~ese systems typically used a narrow band FM recording of
d~e modulated analog signal and s~ored a single video frame
with eac~ rotation of ~e disk. AI~Lough p~oviding ~he user
with some excellent advantages, such as a high image storage
density and quick access times, these units we~e suff~cie~ltly
expe~sive to limit their use to high priced systems iII
broadcasting and medical ima~g. Fur~er, ~ese early uI~its
we~e limited by ~e irregularities in and o~ the surface o~ the
recording media. This led researchers at that timc to
discover t~t frequency modulation, Yersus amplitllde
modulation, was a more ef~ective way to e~ode ~e video
signal. These systems also required a high head-te)-media
relative velocity of 1,00~ to 2,000 i~ches per second~ due to
head gap lengths, short video wave lengths required, alld
high signal-to-noise requirements. In ~e floppy disk
~ersions of ~ese systems where the heads were in co~sta~t
con~t w;th ~e media, the u~eful li~ ~as limited, usually
less ~ 0 hou~. Irl the rigid disk ~ersio~s~ useful li~e
migh~ approa~h 2,500 hours prolonged by the air space
between ~he heads and media, but limited due to
~ u~ach~ring impe~feotions, wear from occasional head-to-
media contact, a~d o~er ~actors.
Image storage technology today is c~aractetized by
~e mo~rement from ~llm and slides to videotape a~d video
disk to digitized images in digital mass storage. This recent
tech~ology has taken two directions: ~e ~Irst is a irend
toward digita~ ~tideo disk or CD-ROM (Compact Disk - Read
Only Memory); the second, a trend toward WORM (Write
Once, Read Ma~y) storage. Both of these tech~ologi~s have
signifi1cant drawbacks in ~at ~ey are not erasable and suffer
69
~om high media ~torage capacity reqllirements. The market
today has seen ~e i~troduction of lower cost, high quality
digitizetl storage of ima~es. However, ~e problem as
p~eviollsly l~oted wi~ storage ~ color ~mages in digital ~orm
is ~at it takes a tremendous arnount of info~mation storage
c~acity9 typically soo~ kilobytes of sto~age per Image.
The need for a compact, ine3cpe~ive, to~ly self-
contained image recorder, ~torage unit, playback and
moni~ori~g dev;ce ~or storLng large ~umbe rs ~f hi~ ~uality
lo s~ill color images is apparent in ~everal fields: secunty ~d
sur~eillance, entry access system~ computer penph~rals,
training devices, and pictu~e archiving ~y~tems~ d as a
replacement for color slide p~jecto~, to name oI~y a few.
lS Summary of the In~vention
It is ~erefore an object o~ ~e preseslt inve~tion to
provide an ~mage storage and re~ie~al apparatus capable of
storing a large ~umber of high quality 5till color images a~d
retrievi~g those image~ rapidly for di~play and fur~er
processing.
It i~ fur~er asl obj~ct of ~e pre~ent invention eO
provide mean~ ~or corrgcting ~omalies ~ ~e time base of
the video signal~ whiçh anomalies l~sult ~rom storage and/or
~triev~l of ~e sdll color images.
It is likewi~e an object of the prese~t inventioll to
:- p~ovide an image storage and retlieval apparab~s having an
au~iliary memory for storing corrc~ponding data such as
. time of day, da~e, c~era lens i~ormatio~, time base er~or
information, etc., correspo~ding to each of ~e stored still
color images.
It is also a:~ object of ~he prese~t invention to
provide mea~ for huldi~g a first image rebrieved ~rom the
: ~ storage medium dunn~ ~e subseque~t retricval of a second
image from the storage medium so ~at ~e two images may
be ~issolved, blended, overlaid, or ompared in other
fashions.
l[t is likewise a:ll object of ~e prese~lt inven~ion to
provide an ~age storage and re~ieval appa~atus in which
the s~orag~ medium is erasable so ~at image~ may be s~ored
or ~placed by o~er i~nag¢s as desi re~.
III order to a~tain ~he foregoing objec~iv s, ~e
~age storage and retrieval apparatus stores aIld retrieves a
~umber of still images from a storage medium. The
apparatus comprises a ~to~lge medium7 prefer~bly a high
speed magnetic hard disk, a servo~coII~olled motor îor
rotating ~e disk at a presekcted speed, read/~te !heads and
circuitry ~or selectively positio~g ~e read/~te: he~d~ to
select aIly olle of a nu~nber of circul~r tracks on ~e ~torage
disk. A secord ci~cuit proceses a ~onventio~al composite
video sig~al and produce~ an analog sig~al which ls
connected directly to dle read/write hea~ recorded on
one tracl~ of th~ ~torage dis~. A play~k c~rcuit re~ieves
~e analog signal ~om one of ~e selected tlacks of ~e video
- 20 disk v;a ~e ~eadJwnte head and ~eco~stitut~s ~e composite
~: ~ video signal. Control means, a microprocessor, respvnds to
~: ext r~ structio~s, ~ucb as ~ keyboard, a computer port
ir~put, or similar con~ol input, selects ~e particular ci~cular
~rack on the storage disk, and selects ~e storage tnode or
re~rieval mode fo~ ~e ~pparat~
^ ~ The record circ~ of the pre$en~ inveIItion
separates a co~ventional composite video ~ignal into i~s
lumi~ance alld chroma compo~ent~, dowII-converts the
chroma comporlent by a reference frequency, preferably
about 4 MlHz, freque~cy modulates the luminance
colmponent, ~ecombine~ ~e modulated lumina~ce and down-
converted chroma compunents to produce aIl analog signai
for storage on ~e disk via o~e of ~e readJwnte ~eads. The
;;: playback circuit upon receivi~g ~e analog sig~al from the
read/write head separates the luminance and chroma
'~
~ ~35~,9
compone~ts7 de3nodulates and delay~ the luminance
componellt, up~o~verts ~e chroma component lback to its
origi~al frequency in a conventional video sig~al and
subsequelltly recom~ine3 ~e ~omponen~s to reco~er ~e
S composite video signal ~or dislslay on a standard video
monitor.
In order to assure cle~ re-record3ng of substitute
images7 an e~9e circuit is proYided whi~h may be either a
high i~reque~cy oscillator or a dccreasi~g reversing d.c.
current switch. The micr~processor for ~e app~ratus upon
receivirlg a command to record an image9 filrst i~itiates an
erase sequence which9 in one emotiment, co~ects thc high
~requency oscillator to ~e ~eadlwrite head to rec:ord the
erase freque~cy for 2 predetermi~ed time. In another
embodiment, tlhe microproce~sor connects a decreasing
reverse d.c. GUrreD~ switclbi to ~e read/write head so t~t each
pass of ~he read/wnte head over ~e circular track has a
decreasing ~nt density. Co~equently9 ~e track is totally
degaus~ed prior ~o reco~d~ the ~e~t ~till color image on the
particularly selected ~ircula~ trac~.
The image sto~ge and retrieval apparatus of the
prese~t in~entio~ assures high quality image storage and
re~ieval by compensati~g for jitter ~at irlevitably occurs in
~h~ speed of ~e spinning ~torage disk~ I~ o~e a~pect of ~e
2S invention, an en~oder connected to ~e spin~le of ~e~ seorage
di~ produces a rota~ion sig~al which, during dle storage
mod~, is cons~tly compared in a pha~e lock loop to ~e
videv sync signal from ~e incom~g eoDQpo~ite ~ideo signal
~n order to control ~e seno-motor which drives ~c storage
disk. In a~o~er as~ect o~ ~e pre~ent in~re~tion, ~e ou,hput of
~e encoder produces ~e refer~nce frequency which is used
to bo~ dvw~o~vert ~e c~oma signal in th~ ~cor~ circuit
and up~onvert ~e chroma signal in ~e playback circuit. In
a~o~er aspect of ~e p~sent inyention, the encoder produces
a rcference signal which is ul~ed in a signal processor to
3~ )9
modwlate the primary red, green, and blue si~als prior to
pr~ducin~ ~e conventional composite video signal wi~ the
lum~aance znd ch~ma composent$.
~n another a~pect of the present inve~ion, an
S a~iliary addressable digital naemory is prwided which h~ a
number of data ba~k~ each correspo~d~ng to a single
3~cordl~g track o~ ~e ~torage disk and a ~umber of words
wi~in each bank. The au~ili~y memory is addressed by ~e
miGroproCeSSor SimUl~aneQUSly YVith addr~ssing the sto~$e
lo disk, alld ~he e~coder produce~ a word count wi~n each
memrry bank so ~at as the storage dlisk spi~s, the digital
memory under cont~ol of ~e e~coder steps along ~ ~e
storage disk. Therefore, correspondil~g data can be stored
in the auxiliary memory, and upon ~etrieval of ~e Istill image
fr~m ~e s~orage disk, ~e auxilia~y memory, steppiag ~long
with ~e storage disk, can output ~e auxiliary i~olmation to
a display or to be used for ~ur~er con~ol.
Also, in accordance with the same auxiliary
memory, ~e ~fonn~tio~ stored can be in~ormation relating
to the jitter experienced by the storage disk during the
storage mode. Upo~ retrieva~ Ihat s~oled e~T~r in~ormati~n
ca~ be re~rievedl a~d u~ed to compensate ~e rgcoYered
analog signal and re~Ye the e~ects of ~e ~ime base errors
~at occllr du~ng storage and re~iev~.
In ano~her aspect of the pre~nt inventio~9 a digital
frame memory is provided to hold a single f~e or image
while the ne~tt image is retrieved from ~e storage disk so
that the two images c~ be mi~ed widl eaGh o~e~ to p~duce
special e~fects such as dissolving, overlayin~, ble~ding, or
~e iike.
Other o~ects and adva~atage~ of the present
Lnvention will become apparent upon reading ~e following
detailed descripdon ar~d upon re~er~a~e to ~e drawings.
6~3
Brief Descriptlosl o~ the Dra~ng~
lE~igure 1 is a bl~k diagr~ showing the ~mag
storage and r~ieval apparatu~ ~ the present iIlventio~;
Fig. 2 i~ a bl~k diagr~ of ~he ~co~d ci~ of
~e present invention;
Fig. 3 is a block dia~dlm of ~e pla~ack circuit oî
~e p~ese~t i~ention;
Fig. 4 is a block diagram o~F ~e e~e ci~uit of ~e
pre~en~ inveD~ion;
Fig. S is a blocl~ diagraln of ~e servo~on~ol
Ci~llit of the present i2lve~ion;
lFig. 6 is a block diagram show~g one me~s of
àme base compensation ~uring ~e s~rage mode;
Fig. 7 is a bl~ diagram ~howi~g o~e ~aeans of
t~e ba~e compensa~on d~g the retrieval mode;
Flg. B is a block diagIam showing ano~her mea~s of
~ne base compensation during ~e storage mode;
Fig. 9 is a block diagr~ showing a modified
record circuit;
Fig. 10 is a block diagram showing a modified
pl~yback circuit;
Fig. 11 i~ a block diagram showing an addres~able
digital au~tilia~y memory which "wallcs along" wi~ the
~age di~k;
Fig.12 i~ a block diag~ showing one mea~s of
using ~e auxili~y memory to provide time base co~rection
during dle retIieYal modey a~d
Fig. 13 is a block diagram showi~g a digi~al single
image di~ital memory for mixi~g two images during t~e
re~ieval mode.
Detailed De~cription of ~he Ill~e~ion
While ~e inventio~ wiil be described ~ connec~ion
with preferred embodime~t, it will lbe under~tood that I do
3s not intend to limit ~e invention to ~at embodiment. On the
~ A 2 ~3 5 5 ~ 9
con~ry, I intend to eover all alternatives, modificatiorls,
and equivalent~ as m~y b~ included within the spin~ and
scope of the invention as de~ d by ~e ~ppended cl~s.
Turning to Pi~use 1, ~here is ~hown the image
s storage and retrieval appa~tus 10 s3f t!he present invention.
~e apparatu~ include~ a rnain storage med;um or disk drive
11. The sto~age medi~ cludes a set of mag~etic dis~s 12
a~d 14 mounted Oll a spindle 16 w}lich spindle i~ rota~ed by a
servo-controlled mo~or 18 at a preselected speed. ~n
0 e~od~r 20 is a~so attached to ~d rota~es with the spindle 16.
The storage medium ll al~o i~cludc~ a readlwri$e head
a~semlbly 22 which includes a re~d/write heacl 24 ~at is
mounted adjace~t to d~e top sur~ace 13 oî ~e disk 12, a
readJ~te head 26 wlhich i~ mou;~ted adjacen~ to the boKom
surPace 15 of the disk 12, a read write head 28 whieh is
mou~ed adjacent ~o ~e top surface 17 of ~e disk 14, and a
.~ read/write head 30 which i8 mouIlted adiacent to ~e b~ttom
surface 19 of ~e disk 140 The rçad/wnte head assembly 22
simultaneously move~ ~e heads 24, 26, 28, and 30 radially
; ~ 20 across ~e disks 12 ~d 14 u~der co~trol of a head drive
means 32.
he disk~ 12 ~d 14 are divided in~o a number of
collce:utric tracks on e~ch of ~he four sur~es, such as tracks
34 and 36 on the top sur~ace 13 of di~k 12 and radially
:: 25 aligned co~pondi~g tracks 35 a~d 37 on the top surface 17
of disk 14. ~e tracks 34 and 35 toge~her (along widl two
similar radially aligned tIac~ o~ the bot~om sul~aces 15 ~nd
- 19 of dislcs 12 and 14) define a~ imaginary cyli~der. In
order to record (write~ i~formatio~ onto ~e traclcs 34 ~d
35 in the storage mode or to 3ense (read) information
recorded on ~acks 34 and 35 in ~e retrieval mode, ~e head
drive means 32 positio~ ~e head assembly 22 so ~a~ d~e
heads 24 and 28 are located above tracks 34 and 35
respectively. By moving ~e read/write heads 24, 26, 28, and
~: 35 30 radially toge~her to a particular selected cylinder and by
:
69
selecting one of the four heads as will be descnbed in greater
detaal, a palticular t~c~c on any one of ~e four disk surfaces
can be selected for recording or for playback.
The storage snedium 11 also has a disk drive
S micropr~essor 38, wh~ch by means of output 40, contsols
the he~d drive 32 a~d ~erefore selects the desi~ed tracks by
positio~ing readlwrite heads 24, 26, '28, and 3(). The output
sig~al on line 42 controls dle speed of the motor 18~ A
sensor 44 is mounted adj~cent the encoder disk 20 and sen~es
dle rotativn of ~e spindle and pr~vides ~at in~ormation to
dle microprocessor 38 by means of input line 46 so that the
mic~oprocessor 38, via output 42~ can control ~e æpeed of
~e spindle as required.
The storage medium 11 including the disks 12
~nd 14, motor lB, encode~ 20, head assembly Z2, head dAve
32, and ~e microprocess~, 38 ar~ pre~erably implemented
by use of a La Pine Ti~ 20 Disk Drive available from La
Pine Technology, ~ilpitas~ California Su~ a disk drive, is
typically used ;n connection with providing additional
storage for digital information Ior persoD~l computers.
1~ addition to ~e disk drive 11, the Pv~rieval and
storage apparatus of the present invention comprises a
record circuit 50, a playback circuit 52, and con~o~ means
~: 80. The ~eco~d cir~uit S0 receives a conYentional composite
video sig~al at its i~put 54, processes ~at signalS and
transmits ~e processed video signal to head multiplexing
cir~uit 56 via record ou~put 58, isolatio~ switc:h 6n, a~d
t~ansmission line 62. 'llh~ p~cessed video signal on line 58 is
an a~alog s~g~al which is co~ected ~rough the head
multiplex circui~ 56 to any one of the four output lines 64,
66, 68, and 70 which are connected respectively to
read/wri~e heads 24, 26, 28, and 30 for storing the analog
sign~l onto one of the four selected tracks on one of the two
disks.
1~
Alterna~ively, in the retrieval mode, the
information se~sed by o~e of ~e four readl~te heads 24,
~6, 28, a~d 30 is co~nected via ~e head multiplex circuit 56
to the t~nsmission line 62, through isolation switch 6n, and
s to illput 72 of the playback cir~uit 52. The playback circuit
52 receives ~e analog signal on line 72 and reconstitutes the
composite video sigllal on its output 7~ ~vhic~ is connected to
- moni~or 76 and t:o awciliary output 7~. The record circuit 50
and playback cir~uit 52 will be Idescribed in greatcr detail
below ~ connee~on with Figs. 2 and 3.
The image storage and reb~eval appa~tus lû is
operated under ~e control of co~trol means 80 which is a
microprocessor. The micropro~essor 8û ~eives c:ommands
f~om any appropriat~ input means such as keyboard 92 or
RS-232 computer port ~4. l'he RS-232 port 94 l~fers to a
s~ndard port with de~ned pin connec~ions, signal levels, and
the like promulgated by the Electronics Industries
Association of Washingto~; D.C., denoted as RS-232-C
(August 1969~ a~d en~itled "Interf~ce Betwee~ Data
Terminal Equipment a~d Data CommuDications Equipment
Employing Serial Bi~ary Data Interc}lange". The
microprocessor also provides an indication on line 96 of the
particular image being stored or retrieved w~ich status is
the~ displayed o~ display 98~ Ths microprocessor 80 is
2s pre~errably a Zilog Z8 manufactured by Zilog, Inc. of
Cupertino, Califon~ia.
The microprocessor 80 by means of` output 84
instructs ~e disk driYe microprocessor 3B to move ~e head
assembly 22 radially in or out, and ~e output on li~e 82 tells
microprocessor 38 how far the head assembly 22 should be
moved radially. Upo~ receipt of ~e direction and step
instructions on lines 84 and 82, the micr~processor 38
instructs head drive 32 to move the head æsembly 22 so that
the read/write heads 24, 26, 28, and 30 are adjacent a
.~ ,... .
.3
11
p~cular seles:ted cylinder and the four circular traeks on
the disks ~at define ~at oyl~nder.
C)nce the microprocessor 30 has caused the
microprocessor 38 to select a particular cyli~der, the
s microprocessor 80 selec~s one ~f the read/write heads 24,
26, 28, or 30 by mea~s oï a multiple~ ins~ctio~ OD. line 86
which controls multiple~ ei~suit 56 and sallses multiple~
circuit 56 to select o~e of i~ signal lines 64, 66, 68, and 70.
The microp~ocessor 8Q also ~e~ect3 the storage
0 mode or the retrieva3i mode ~r ~e apparatu~ 10. If ~e
storage mode is selected~ the microp~essor 80 first selects
the track and headl and the~ ccordance with ano~er
aspect of the present inve~gio~, ~he microprocessor 80 via
ou~:put line 102 activates e~e circuit 100. lhe erase circuit
100 co~ec~s an erase signal to transmis~io~ e 62 via erase
output 10~ and ~e~ to ~e seiectgd head ~ ~e disk drive via
~e multiplexer 56. While ~e erase s~que~ce i~ enabled, ~e
microproce~sor also is~es a command on OlltpUt 108 to open
i~olatinn switch 60 which a~su~es ~hat ~e erase signal on li~e
104 is not connected back into ~e r¢co~d circuit 50 or the
. playback circuit S2. The erase circuit is selected for
predetermined amou~t of time to assure ~a~ ~he sel~c~ed
~rack has been appropriately erased and deg~us~ed. The
erase cir~uit will be described in greater detail lbelow i~
co~ec~ion wi~ Pig. ~.
S:)nce ~e era~e s~uence has ended, isolatio~ swit~h
60 is closed9 and ~e microproce~sor 8~ by means of output
li~e 106 ~elects record circuit 50 and disabtes playback
circuit 52. With ~e reeord circ~it 50 enalbled, the standard
~: 30 composite video signal on line 54 is p~ocessed a~ connectedvia lines 58 and 62 and multiple~ circuit 56 to ~e elected
read/write head.
-~ Qnce the storage seq~ence has e~ded, and an
~: . instructio~ for retrieval ha~ been received lby the
3s microprocessor 80, ~e microprocessor, after se~ec~ing the
.
~.2~ 9
desired track andl head, issues a command on line 106 to
disable the record circuit 50 and to enable the playback
circuit 52. The piayb~ck ei~cuie 52 receives the recorded
- analog signal and reproduees ~e original composlte video
signal.
In opgration ~e apparatus 10 comes up in the
re~rieval mode when ~rlled on. An ~utomatic initialization
seque~ce in disk dAve microproce~sor 38 oscurs which
places ~e head stack a~sembly at tracks 000, ~e outermost
0 ~ack and gives an indic~ion to mic~opr~cessor 80 of the 000
ps:~sition on line 88. The main con~ol microproces~or 80
~en takes co~ol ~F all aspects of ~e operation of the ~t
including updating ~e display 98 with the current image
number a~d monltori~g the keyboard 92 for ~perator input.
1S If one desires to view or record a di~erent image other than
~e one curre~tly bei~g viewed, ~e glumber is e~ltered
through keybQard, calculatioDs are made wi~in main control
m;croprocessor 80, a~d the appropriate direction and step
signals are sent to the pro~essor 38 via lines 82 and 84 ~o
move ~e head assembly 22 to ~e appropriate cylinder and
traeks. In addition the microprocessor 80 selec~ the
appropria~ read/w~ite head by mean~ of cont~ol line 86 and
:~ ~nultiple~er S6.
While o~er track and ~age notation schemes can
2s be u~ilized by ~he apparatlls depending on the particular
- application, the notatio~ standard used for ~he presentinvention is one i~ whi~h ~e outermost cylinder contain ~e
lowest numbered tracks. S~ing at ~e top surface 13 and
~e outside track, dle surfa~es are numbered #0~ t2, and
#3 (top to bottom) on ~he first cylindler, cylinder #0. l[he
rst image, ima~e #0, is therefore on the topmost sur~aces 13
~- of disk 12. It is very simple to dete~ine cylinder and
sur~ace number for any given video image. One simply
divides ~e number of the desired image by 4 (~e number of
33 surfaces). The quotient is ~e number of d~e cylinder, and
~ . .
:, .
13
the rem~inder i~ ~e sur~ace number. For example, to
determine the l~ation of ~age ~1733, dividing 1733 by 4
gi~e~ a result o~ 433 wi~ a remainder of 1. Therefore,
image 1733 is l~ated on ~ d~r #433~ surfa~e #1.
Re~rrin~ to Fig. 2, ~h~re is shown a block dia~ram
for ~e record ci~cuit 50O The r~olrd circuit S0 includes a
lumiIIance/chroma separator circuit 120, a lu~:ninance ~M
- modlllator 1229 a mixer 124, an enable switch 126~ a
~terodyne ~requency conver~er 128, a refere~ce o~illator
0 130, and a low pass fflter 144.
A st~da~d composite video ~ignal is connected to
input ~4 of ~e ~cor~ ci~t 50. ~e composite video signal
on ~put 54 is fed to lum~ee/chroma sep~rator 120 where,
using convention~l separation ~ech~iques, ~e lumin~ce
- 15 signal is separated and m~de ~vaii~le on liLle 132, ~e
chroma signal i~ ~eparat~d a~d made available on line 134,
and ~e video ~ync ~ sepa~a~d a~d made ~vailable OQ
line 136~ The h~nallce signal on line 132 is fed to ~e
luminallce FM modulator 122 where it iB modulated in
conventional ~as~ion, a~d the FM modulated luminance
signal appea~, o~ 138.
l~e ~oma ~ignal on li~e 134 is csnnected to
heterodyne freque~cy conv~r~er 128 wher~ ~e chroma
sigD~l is beat wi~ a first re~e~ence ~requency on input 140
2s ~rom the refere~ce oscillator 130. Particula~ly, the
re~re~ce frequenc~ is 4.268 MHz which, w~n heterodyned
wi~h ~e 3.58 MHz ch~ma sign31 o~ line 1 3D" p~oduces sum
;: and di~feren~e f~uencies o~ output litle 142. 1~ low pæs
: filter 144 elLminate~ ~e hi~h freque~cy produced by ~e sumof ~e reference frequency and the chroma signal and passes
~e low frequency di~er0nce signal to its output 146. l[~e
signal on output line 146 from ~e low pass filter has a
~ii frequency of approxim~tely 688 KHz. The down-converted
chroma signal on line 146 is then mixed with the F~l
3S modulated luminance signal on line 138 by mixer 124 to
14
produce a compositc processed analog video signal on line
148. If the apparatus 10 is in the storage mode, the
microprocessor 80 p~oduces a~ en~ble signal on line 106
which closes enalble switch 126 to connect the proce~sed
a~alog video sigaal oa line 148 to the outpu~ 58 of the record
circui~ 50. T~ p~ocessed analog video 5i~ C~ le 58 iS
the~ co~ec~ed ~hrough i~lation ~witch 60 s to tr~smission
line ~2, to multiplexer 56, and ~ d~e selected he2d.
Turning t~ Fig. 3, ~here ~s shown a bl~ di~8~
- 10 of ~e playback cir~uit S2 which compri~es a disable switch
150, a high pass îiltcr 152, an amplifier clipper 154, a
lum~a~ce FM demodulator 156, a dela~ line 158, a mixer
160, a low pass ~llter 162, an automatic gain con~ol 164, a
re~ence oscillator circuit 166, and a heterodyne fhquency
conYe~er 186.
The playbaclc circuit 52 receives thg a~alog video
si~al from ~e ~ead O11 ~nput IjQC 72. If ~e retrieval mode
~as been selected by ~he microp~ocessor 80, disa~le switch
1 Sû is closed by a sigIIal 031 line 106 from the
micr~proce~sor~ and ~e analog video sig~al o~ line 72 is
co~nccted to line 170. ~18 ~Og SigI~al 011 li~e 170 haS ~e
~e frequency compo~itio~ as ~e si~al produced by ~e
~ecord cirG~it on line 58. The ~a}og video sig~al o~ line
170 i~ connectet to ~e high pa~s ~ilter 152 which separate~
~e high frequenGy component, which i~ ~e lumi~ance
comLponent, and connects ~e luminance cornponent to line
172. The luminallce compone~t on line 172 is amplifled, and
~e peaks are clipped L~ c~ve~tio~al fa~hion by ampli~ler
clipper 154. The output o~ e 174 is conneclted to dle
luminance FM demodulator 156, and the luminance
component of the original video ~ig~al is re60vered on line
176. The lu~nmance component îs then delayed for a
predetermined arnount o~ time by a delay line 158, and ~e
delayed ~uminance componen~ appears at line 178 which is
3s ~e input to mixer 160.
,~f~5q3~3
A~ the same time, the low pass filter 162 extracts
~he ch~oma compo~e~t from the processed analog video
sig~al on line 170 and feeds ~e chroma component to ~e
automa~ic gain control circui~ 164 via line 1~0. The
au~oma~ic gain control adju~ts the gain of the chroma
compone~ The c~roma com~nent on 1~ 182 at dle output
of ~e a~t~ma~ g~ cont~ol ha~ a ch~teristic frequency
of 688 ~Hz wi~ di~k ~itter ~rrors superimposed ~ereon.
The chroma component o~ e 182 is cosnected to up-
co~verter modulator lgO which sums the fr~que~ he
shroma signal (688 k~Hz with ji~e~ erro~ wi~ a refere~ce
~r~uency of 3.58 MHz on line 1843 the output olF ogsi~lator
1~6~ Oscillator 186 also produces a 3.58 P~Iz sign~l on its
o~er output 188. The up co~ertgs mo~ula~or 190 produces
1~ a~ its outpu~ 192 the sum o~ ~e ~reque~cy on li~e 184 (3.58
~Hz) and the chroma sig~al on l?~e 182 (6B8 ~IZ`J. The sum
~ig~a~ on line 192 ha~ a ~re~ue~y of 4.268 MHz and is
connected to p~e loek lcop 194 where it is compared t~ the
output of up-~conv~rter :modul~or 196 on line 198. The
outp~ o~ the pbase loc~c IQOP on l~ 20~ con~ols ~e voltage
controlled oscillator 202 to a ~equenGy of 6B8 klEIz which
~ppear~ at it~ output on li~e 204. The 688 kH2 output o~ line
204 is up~onver~d by the 358 MHz ~efernce frequency on
~ e 18~ by mean~ of up-conYerter modulator 196. The
rewlting output on line 2~6 ha~ a relatively stabilized
~uency of 4.268 MHz which i~ con~e~ted t~ ~e fre~uency
conve~er 168. The fre~ue~cy converter 168 up-con~erts
~e ch~oma ~ignal (688 kHz) by means of ~le reference
fre~uellcy o~ line 206 (fl.268 MHz) to a signal on li~e 208
having a frequerlcy of 3.58 M~Iz. The up~onYerted chroma
compoIlent on l~e 20R i~ coDnected to ~ mixer 160 w}lere it
is combined with delayed lumina~ce compo~e~t on line 178
to reproduce the staIIdard video signal on line 74.
Turning to Fig. 4, ~ere is ~own a block diagram
of ~he era~e circuit 100. The erase eircuit 100 include~ a flip-
~ q~ 9
1~
flop 212, counter 214, alld decreasin~ current switch 216.
When ~e microprocessor 80 initiates an era~e sequence, it
enables ~ rase ci~ui~ 1~0 by rneans of a~ erase command
on input 102 which sets flip-f~op 212 produsing a logic "1"
s on il:s Q output 218. The logic "1" on line 218 enables
counter 214 which begi~s coumting with each ~ucccssive
index pulse o~ line 210. The in~e~ pulses on line 210 are
produ ed by the microprocessor 8û each time ~e
microprocessor 38 far t~he di~k drive determi~s that a
single revolution of ~e disk ha$ occlllTed. ~e index pulses
are ~ed from microprocessor 3$ to microprocessor 8~ by
means Qf li~e 90, and ~ ~de~ pulses on li~ 90 a~ the~
passed by microprocessor 80 to ~e e~e c~it o~ line 210.
The count 214 sequentially puts a lo~ic "1" v~ ea~h of it~
ou~puts 220, 222~ 224, 226, ~28, 230, and 232. Wi~ each
logic "1" an outpu~ 220-232 ~e curre~t swith 216
p~oduces a reverse d.c. current on its output 104 which is
connected ~rough tran~is~ion line 62 and ~ultiplexer ~6 to
~Le selected head. When ~e first lin~ 220 is a logic " 1", ~e
reve~ing cllITe~t switch 216 prodllce~ a ~gh d.c. current on
~: its output 104. Wi~ each successive lo~i~ "1" on lines 224,
~269 22~, and 230, the reversc cur~nt 3witc~ produces
::~ lower a~d lower d.c. ~e~t le~el~ at its output 104. Oncethe count has reached N wi~ a logic " ln o~ line 230, ~e
2~ reYerse curre~t switch produces ~he lowest cwre~t, and wi~
- ~he ncxt cou~ counter 214 produce~ a logic, "1" at its
~utpu$ 232 which r~sets flip-flop 212 and d;sables coullter
;: 214. ~ce tlhe colmter 214 ha~ counted ~ugh its sequence
~om 1 to N and ha~ been disabled, ~he erase sequence e~ds.
Alternatively, ~e reverse current switch 216 may
be replaeed by a high frequency osoillator which produces a
12 MHz to 16 MHz o~tp~t at li~e 104. The oscillator is
enabled until the counter 214 has cou~ted to N + 1. lhe erase
sequence assures that the trac~ is totally erased of a prior
3s image and appropxiate1y degaussed so ~at storage on tha~
.
17
track will not be af~ected lby re~idual e~ects o~ ~e previous
~g~-.
Another im po~tant aspect of the present invention
i5 ~he ability to compe~sate for time base errors in ~e
S sto~ge and retIiçval of images ~at re~ult from ~he inevitable
jitter in the speed of the spi~ ing mag~etic disks.
Particularly, wi~ refere~ce to Fig. 5, ~ere i~ ~hown a serv~
control circuit 250 compri~ing a phase l~k loop 252 and a
voltage controlled o~cillator 2540 In accordaaace with
conven~ional practice, the mic~oprocessor 38 o~ ~e di~k
dnve 11 a ha~ stable oscillator which providles a timing
re~ere~ce for the microprocesso~ to use ~ co~l~o~ g the
speed of t~e spi~lile 16. The mic~processor 38 se~ds a
co~ol signal on Ii~e 42 to motor amplifier 258 which in
turn controls ~e speed of the moe~r 18. The speed of the
spindle 16 is seDsed by meaas of ~h¢ encoder 20 alld sensor
44, a:~d ~e encoder ~ al is connected bac~ via Iine 46 to t~e
mieropr~cessor 38 to p~vide adjustment of ~e speed of ~e
motor accordingly
In a~cordaDce wi~ ~e pres~ inveIltio~, line 46 is
connected to ~he phase lock loop 252 through
microprocessor 38 and mic~op~essor 80. ~e phase lock
loop ~Lso receive~ ~e Yideo sy~c si~nal on li~ 256 from ~e
reco~ c~i~ 50. The phase lo~k loop c~mp~ ~e speed of
2s the ~otor represented by ~h~ enc~der si~ o~ line 46 to ~e
- video sync ~igIIal on line 256 ~Dd prod~ce~ a dif~erence
~: signsl Oll tin~ ~60 ~he diff~r~e sig~al on line 260 ~hen` :~ serve~ t~ c~n~ol the voltage co~t~olted os~illator 254 which
: ~ produces a timing refet~ce o~ i~s o~lqpu~ ~62. Th~ ~o~tage
controlled oscillator 254 thereby replaces the stable
oscillator previously described which p~ovided ~he timing to
- ~ ~e microprocessor 38. Conseque~tly, the seno-control
cireuit 250 co~trols the speed of the motor 18 in
synehronization wi~ ~he video sy~c sign~l, While the servo-
control circuit 250 cannot eliminate jitter from ~e speed of
,
,,''''
;
.~s~35g3
1~
dle disks, it does assure ~at, iZl a gros~ scDse at least~ ~e disks
are r~tating once for ea~h complete video ~age.
Turning to Fi8. ~, and i~ co~ection wi~ another
important aspect of ~e present inve~ion, there i~ shown a
s reîerence frequency c;rcuit 270 which comprises the
encoder 20, its sensor 44, a3~d a freque~cy co~verter 272.
Figure 6 also show~ ~e record cia~ 50 which receives ~e
composite video si~nal at its iDpUt S4 a~d produces the
processed analog video sig~lal at its outp~t 58 as previously
o described. The processed analog ~ideo si~al at ou~ut S$ i$
connected ~rough isola~don ~tch 60 a~d multiple~cer S6 to
one of ~e four ~eads 249 26, 28, a~d 30. The reference
frequency circuit 270 sen~es ~e s~eed ~ ~e spiDdle 16 by
means of encoder 20 and se~sor 44. ~he encoder signal on
line 46, which is pr~portio~al in ~quell~y to ~e speed of
~e spindle7 is co~ne~ed to t3he f~equency comerter 27~ (as
wel~ as to ~e micr~oc~s~or 38) where it i~ convertcd to a
reference frequency of 4.26$ MHz o~ line 274 ~or the
~ominal rotational speed of ~e di~ks. The reference
frequen~y on line 274 ~es in ~regue~cy in ~cordance wi~
~; ~e v~ations in ~e speed of t3he spindle lG. Therefore,
whe~ ~he refePvnce freque~cy on line 274 i5 co~e ted to
heterodylle frequency converter 128 of ~e lecor~ clrcuit S0,
~e rcslllti~g freque~cies ~rom ~e he~er~dy~e frcquency
converter 128 asd ~re~ore from ~e mixer 1~4 Yary in
` ~ acco~dance wi~ ~he variation~ in ~e gpeed of ~he disk.
Co~equently, ~e frequen~ o~ ~e sign21 on lini: 58 at the
output of ~e r~ord circllit .is ~lme ba~e compeDsatcd whe~ it
as recorded onto dle dis~c. It should ~e appreciated ~at ~e
reference sig~al could al50 be produced by providing a
prerecorded re~rence sig~al on ~e magne~ic disk and that
~e term encoder as used herei~ refers ~ bo~ a separate
encoder such as 20 and the disk itself wi~ a reference
frequency recorded ~ereon.
~ ~35~39
In connection wi~h ~etrieval of t3he analog vid~o
signal g~om ~e disk and wi~ reference to Fig 7, ~ere is
provided a ~ference frequency circuit 2~ comprising ~e
same elements as ~e reference ~reque~cy circuit 270.
s During retrieval7 ehe 4,268 ~Hz signal at ~e output 274 of
~e freQuency co~verte~ 272 i~ ~:onnec~ed t~ lhe ~re~,uency
conve~ter 168 of ~e playb~k c~cui~ 52. Cons~uent~r, if
jitter resul~s i~ ~e speed of ~e disks du~g re~rieval9 that
ji~ter also appears is~ ~ ~equency OD~ e 274 so ~at when
lo ~e chroma compone~t is being up-converted, the jitt~ at ~e
input 72 to the playba~ ci~ui~ 52 is compe~s~ed by an
offsetti~g jitter in t~e frequensy on li~e at 274.
Consequent1y, ~ ~ference frequency circuits 2'70 and 280
together provide c~mp~ete time base compel~sation ~or ~e
- 15 video signa~s bo~ d~g storage and re~ieYal.
In ascordance wi~ another asp~ct of ~e prese~t
e~ioll, it is pos~ible to provide time base compensa~ion
: ~: both in connectio~ wi~ ~e frequency c~ver~ion~ of ~e
ehroma ~ignal or at a~ earlier s~age in connt~ction widl
gene~a~ng ~e 3.58 MlHz C~¢OMa SigDaL II1 ~a~ connection
- and with refere~ce to Figure 8, there is shown a signal
proce~sor 300 whic~ i~cludes a ma~rix c~rcuit 302, a red-
` ~ minus-luminance modulator 304, a blue-minus-luminance
modulator 306, a phase shif~ circui~ 308; and a combining
- ~ 25 amplifier 310. 'rhe outputs 132 ~d 134 of the signal
processor 300 are connected to the record circuit 50 at lines
132 and 134 as ~own in Fig. 2. Consgque:ntly, in ~he
~: modified versioIl of ~ record circ~ 50 includi~lg ~e signal
processor 3ûO, ~e Y/C sepa~ator 120 may be elimina$ed.
C)~herwise, the lumi~ance sig~al OB ~ 132 and~ the ehroma
signal on l~ne 134 ~re plocessed for recording ~ ~he same
- fashion a~ previously de~cribed in coDnection wi~ record
eireuit 50.
In connection with ~e signal processor 300, an
3s image 312 is recorded by a vide~ camera 314 in con~ention~l
~
~a~hion to produce a red ~;gnal on ~ine 3169 a ~re n signal on
line 318, and blu~ signal on li~s 320~ Th¢ camer~ 3~4 also
h~ an o~cillator whi~ producs~ a sync Sig~ on l;ne 136.
lhe red, green, and blue sig~als ~e connected to ma~rix
cixcui~ 30~ whi~ produce~ a hlm~ce signal on lins 132, a
red-millus-lusn~ e signal on line 322, ~d a blue-minus-
l~in~e signal a~ e 324. ~ color compon~ s on ~ineS
322 ~d 324 a~ modulated wi~ a 3.58 ~Iz re~rence signal
on li~e 326. Th~ 3.~8 ~A[Hz signal on li~e 326 is derived
from ehe ~reque3lcy ~o~verter 272 shown in Fig. 6 and 7 aIId
varies i:~ ~cco~ance with any v~iation i~ the spee~ of ~e
disk drlve. The 3.58 MHz re~erence sig~al on li~e 32,6 i~
cosnected to ~d-mi~us~luminance modulator 304 alld to
blue-millus-lumin~ce modu31ator 3~6 ~ough 90 phase
lS ~hift ~i~uit 308. The output 328 and 330 of ~he red-minus-
lumi~aace modutator 304 a~d ~e blue-minus-lumi~ance
modulator 306 re~pecti~e~y are co~ected to combining
amp~ifier 310 w~i~ comb~es ~e two color ~omponent~ int~
~e 3.58 MH2 chroma sig~l o~ e 134.
Because the r~ere~e signal on line 326 varies in
accor~ce wi~ the jit~er of ~e dislc drive, ~e chroma ~ig~al
~: is compensated at ~he ~ne it is modul~ted to 3.58 ~z andagain when it is down~o~ve~ted to 688 ~ in the conYerter
128 (~ig. 2). It should also be a~preciated ~hat ~e 113minance
2s sign~ on lil~e 132 ~d ~he ch~oma ~ignal on l~e 134 could be
recorded on ~o separa~e ~acks on ~he disks ~or later
- ~pa~ate retrieval a~d p~ocessi~g.
In ac ord~e wi~ a~oth~r aspect of the prese~t
~ventio~, it m~y be d~sirable in co~ection wi~ p~o~iding
very high quali~y color pictures to record ~e red sig~al,
gr~e~ signal, and blue sig~al ea~h on a separate ~ack on the
magne~ic disks. With refere~ce to Figo 9~ ~e record circllit
50 of ~ig. 2 is replaced by a modified record circuit 360
which includes FM modulasors 362, 364, and 366 wi~h
3s output~ 368, 370, and 372 respec~ively. The video camera
-
314 generates separate red sig~al 3169 gr~en signal~ 318, and
blue ~ignal 320. Each ~ eparately FM modulated by
modlllator3 362, 364, and 366 which are co~ve~tiolla~ i~
nature. The output~ of ~e FM rnodulators are co~nected
di~ctly to recordia~lg head~ 24, 26, al~d 28, respectively,
through appropriate i~olation switche~ ~uch as ~8.
Consequently, e~h of the recording heads 24, 26 and 28
separa~ely ~cord~ the red, green~ or blue ~ignal o~ ~ree
sep2~ate ~k3 of ~e disks.
With ~e modi~1ed ~co~l cir~uit 360 sho~ in Pig.
9, it is ~ecessary upo~ retrieval to modify ~he playback
circuit to receive ~d process the individual recorded ~hree
color compone~ts. Tu~ng to Fig. 10, there is sho~ an
al~e~native playback circuit 380 which can be used where
ea~h co~or component, red, gre~, ~d blue, i5 recordPd on
a~ individual t~ck. The pl~y~ack ci~ui~ 380 comp~ises F M
demodulator~ 382, 384, a~d 386, mat~ix circuit 388,red-
minus-lumi~ance modulat0r 390, blue-lninus-lumi~ance
modulator 392, phase shiR c~uit 394, combi~ng amplifier
396, and combini~g arnplifier 398.
lC)uring retrieval, dle analog sig~ r~m heads ~4,
2~ d 28 are receiYed on i~t line 400 for r~d, 4û2 for
green, ~nd 404 for blue. The color compo~ent signals are
demodulate~ by ~ demo~ulators 382, 3~4, and 386, and ~e
2s demodul~ed sig~als are connected to ~e ma~ Ci~Uit 388.
The matri~ circuit 399 arithmetically combine~ the
~' demodula~ed color components to produce a luminance
si~al o~ line 406, a~d red~minus-lum~ce signal~ o~ line
408, a~d a blue-m~nus-luminance signal on line 410. The
two color comp~nent ~ignal on line 408 and 410 are
modula~d by mo~ulat~r~ 3~0 and 392 to ~e ~equency oi
3.58 MHz widl ea~h modulat~d color componeat bein8 90
out of pbase from the o~er. The resulti~g modu}ated color
compon~nts are combined by combining amplifier 396 to
- ~ 3s produce a single chroma 5i~1al OII line 412. 17he chroma
" .:
,'''
: .~
22
signal on line 412 a~d the lumi~ance sig~al on line 406 are
the~ combined by combining amplifier 39g to produce a
sta~da~ composite vid&o signal on line 74 which is ~en,
wi~ reîerence ~o Fi~ure 1, coanected to monitor 76 and to
s au~iliary ou~pu~ 78.
ln acco~an~e wi~ ano~her aspect Qf ~e present
inve~tion, it may upon occasion be desi~able to record
certain information digitally concerning ~e ~ature of ~he
image such as t~me, dlate, lens se~ g, or other pertinerl~
i~ormation at the time thc image i~ ~ecor~ed on the disk. II1
~at regard and with re~erence to Fig. 11, there is shown ar~
au~iliary digital memoly 420 having a memory a~ay 425,
w~ich is divided into N n~mb0r of memory banks 426 with
each banl~ h~ g M ~umber of w~rds 428. The 'ba~ are
selected by a bi~ary cou~ter 430, a~d ~e wor~is an~ selected
by a bin~ry counter 4320 The au~iliary memory 420 has a
data inpu~ 4229 a ~ata o~tput 424, a sloc~c input 350, and
address lines ~2, 84, a~d 86. The au~ciliary memory 420 is
addressed by ~e microp~ocessor $0 so that each bank
cor}espo~ds to a single circular trac~ on l~e disks. The
Sigllal5 on line 82 and 84 by mea~s o~ a b~ cou~ter 430
select a group of four banks co~esponding to the radial
position of ~e head assembly ~, and ~e sig~al on ~ine 86
abas~ wi~in ~e elected g~up which co~responds to
2~ o~e ~P the ~our heads which has been selected ~or storage ~r
retri@val. - -
A~ ~e disk~ rotate, ~e e~coder 20, ~e sensor 44,
and ~he frequency converter 272 produce a synch~onized
cl~k oll line 350. The cloc~ on line 3S0 con~ols ~e b~nary
counter 432 which continuously colmts from 1 to M number
of wor~ ea~h bank. Consequently, wi~ ~he ban~Ls seleeted
by ~he address fr~m ~2 processor 80, the au~ilia~y memory
420 cycles ~om word 1 to word M and repeats in
~ synchro~i~atio~ with the disk making one full revollltion.
;.
There~ore, it c~ be said ~at ~e words L~ each memory bank
"walls ~long" wi~ ~ i~orm~ti~ on ~e disk~.
C)ne pa~icularly advan~ageous purpose of the
~u~cilia~y memory 420 is to store ~i~ae base e~ror~ which
s ~cur during storage of ~e images o~ the disks. T~g to
Fig. 12, there is showII a ~eheme ~or using the au~iliary
mPmory 420 ~or ~a~ purpose. A tim e ba~e c~ction circuit
soo compnses a compa~LbDr 502~ a stablc ~me b2~e oscillat~r
504, a ~witch 506, ~ m~g cirwit 508, a~d t~e base
'!' 10 co~rector 510. Particularly, d~e compara~ receive~ at its
input 46 the sig~al from t:he erL~oder 20 ~d ~ensor 44 ~d
receives the output ~ ~e s~ble oscillator 405 at i~put 512.
The eompara~or produçe~ a digital error signal on ~e S14
which is proportional to the variation ~tween ~he ~lpeed of
S ~e ~pindle 16 (line 46~ and ~he fr~uency of the stabl~ time
base oscillat~r 504 (line 51~).
During the storage mode) switch 506 is co~nected
to input 422 of ~e auxiliary memory 420, and ~h~ di~tized
errvr ~i~nal on line S14 rel~t~B to the jitte~ is stored i~ the
memory 420 as the dis~ make~ on one revolution. Upon
eompletion of ~e storage mod~, s~ch ~ is to~led to line
516~ a~d ~e all~iliary memory 420 begi~s reading out ~e
digi~zed error i~ormatio~ onto its ~utput 424. Duri~g the
retrieval mode, ~e comparator co~tinues to produee digital
2s ~me base error i~formatiQ~ on Imc 514 (~d ~herefo~ lin~
516~ w~ich i~ summed wi~h ~e time ba~e error is~omlation
Pf~m ~e ~wciliary memory 42~ by ~umming c~ui~ 508. By
cornp~nng the tlme ba~e erro~ in~ormation stored in
auxiliary memory 420 dunng ~e storage mode to ehe time
base error information produced during ~e retrieval mode,
a time base correctio~ signal is produced by ~e summing
ci~r~uit 508 o~ line 518. The tim~ base correctio~l signal o~
line 518 is connected to ~he time base corrector ci~cuit input
S10 where it controls dle delay of ~e signal on output 74 of
35~ j9
24
~e playback circuit 52 tQ produce a time base corrector
video output si&nal on line 520.
Fu~er i~ ~ccordance with ~he present i~ve~ion
and wi~h re~erence to lE;ig. 13, ~ere is provided a single
S frame memo~y circuit 60~ whi~ cooperat~s wi~ the s~orage
and retrieval apparatus of ~e present L~vention to allow for
tra~sitioIl betwee~ images during playbaclc ~uch as
dissolving, ov rlay, fade, and other ~pecial ef~ects.
P~icularly, ~e frame memo~ c~it compris$~ a digital
0 memory ~02, an~log-t~digital (A/D) co~verter 604, digital-
to-analog converter (DlA) 606, a~d ~er 608. I~ o~der to
provide the special ef~ec~s of the îrame memory ~Oû, the
p~oces~or 80 f~rst instmct~ the fr~e memory 602 via li~e
614 to store the image that is lbeing ~trieved ~ri~g ~he
~etAeval mode. That is accomplished by fe~ding the video
signal on line 74 f~om ~e playb~ck ci~uit S2 to the A/D
co~verter 604 via input 610. The ~ con-~erter 604
digitizes ~he video signal form ~he pl~ack cir~uit and feeds
the digitized image to ~he frame memory 6û2 via line 612.
t)nce the digital image ha~ be~n stored in ~rame memory
602, the main procsssor 80 call~ for ~ llext image to be
retrieved ~rom the storage medium 11 as has been previously
desc~bed. At the s~e timel t~e microprocessor B0
: ~ commands ~e f~e memo~y 602 via line ~14 to OUtpllt the
2~ st~d image in digital ~rm ontQ its outp~l: 616. Ihe image
~epresen~ed by ~e signal on line 616 is convelted from
digi~l to analog by D/A con~rter 6~6, a~d aII analog video
signal result~ on li~e 618. ~e playback circuit ~2 produces
a composite video s ~ OII it~ output 74. The sig~al on line
61B represents the fir~t image, and ~he sig~al on line 74
presellts ~e next image. The two image~ ~e~, in allccordance
wi~ c~n rentional mixing ~echniques ca~ied out by a mL~er
circuit 608, carl be dissolved9 overl~d, faded one to the
:~ other, or merged to provide a composite output on line 62G.
.:
~ ~ .
5~9
l~e pre~ t i~ve~ltion may al~o i~hlde additional
- ~eaturgs which eDha~ee it~ use~ gs~. ~or e~ample, the
microproce~or ~0 may b~ cont~lled by a remote control
622 much in ~e ~as~ion of the remote cs~trol of a
s co~ven~ional slide projector. The micl~rocessor may also
select image~ er ~e Coll~ol o a audio t~pe device ~24
wbicla can provide a time sequencc o~ image retrieval all in
rela~onsbip to ~e audio being prese~ted.
