METHODE ET DISPOSITIF D'INDICATION DU TYPE ET DE LA DUREE D'ENREGISTREMENT RESTANTE D'UNE BANDE MAGNETIQUE

METHOD OF AND APPARATUS FOR INDICATING A TYPE AND REMAINING RECORDING CAPACITY OF A RECORDING TAPE

Abrégé anglais

SO1183
METHOD OF AND APPARATUS FOR INDICATING A TYPE AND REMAINING
RECORDING CAPACITY OF A RECORDING TAPE
ABSTRACT OF THE DISCLOSURE
A method and apparatus for indicating the type,such
as in terms of overall recording capacity, and remaining
recording capacity of a recording tape. The tape is transported
at a predetermined speed from a supply reel to a take-up reel.
The rotations of the respective reels are sensed and the rota-
tional periods Ts and Tt of the supply and take-up reels, respec-
tively, are determined. Based upon these determined rotational
periods, predetermined characteristics, such as the overall
recording capacity, of the recording tape are indicated, irre-
spective of the arbitrary amount of tape which, initially, is
wound upon the take-up reel. For example, a set of character-
istics is stored for each value of <IMG>; and the one set
which is associated with the determined value <IMG> is
selected. Also, the determined rotational periods Ts and Tt
are combined with certain of said characteristics to indicate
the amount of tape which remains upon the supply reel when that
amount initially is unknown. The latter operation is carried
out in accordance with the expression <IMG>, wherein
TR represents the recording capacity of the taps which remains
on the supply reel, <IMG>, and P and Q are constant
values associated with the type of tape which is used and are
determined by the diameter of the supply (or take-up) reel hub,
the total length of recording tape, the thickness of the tape,
and the speed at which the tape is driven.
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Revendications

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. In apparatus for recording and/or reproducing
information on recording tape transported between supply and take-
up reels, the combination comprising tape drive means for driving
said tape from one to the other of said reels at a predetermined
speed; sensing means for sensing the rotational periods of said
supply and take-up reels while said tape is driven at said predeter-
mined speed, the rotational period of said supply reel being repre-
sented as Ts and the rotational period of said take-up reel being
represented as Tt; means for determining the overall length of said
recording tape as a function of said sensed rotational periods;
means for storing particular identifying characteristics associated
with tapes of different lengths; and means for indicating selected
ones of said stored characteristics in accordance with said sensed
rotational periods.
2. The apparatus of claim 1 wherein said means for
determining comprises means for obtaining a signal representing
Ts2 + Tt2, means for storing representations of different tape
lengths, each stored representation being associated with a respect-
ive signal representing Ts2 + Tt2, and means for indicating the
stored representation of tape length which is associated with the
signal which is obtained.
3. The apparatus of claim 1 wherein said means for
determining comprises central processing means including an arith-
metic section for obtaining a signal representing Ts2 + Tt2,
memory means for storing representations of different tape lengths,
each stored representation being associated with a respective signal
representing Ts2 + Tt2, and comparison means for comparing said
obtained signal to said stored representations.
4. The apparatus of claim 3 wherein each stored
representation is representative of
26

<IMG> ,
wherein Dm represents the maximum diameter of the supply or take-up
reel when all of said recording tape is wound thereon, Do represents
the minimum diameter of the supply or take-up reel when none of said
recording tape is wound thereon, and V represents the predetermined
speed at which said tape is driven.
5. The apparatus of claim 1 further comprising means
for indicating the amount of recording tape remaining on said supply
reel as a function of said sensed rotational periods and at least
selected ones of said particular characteristics.
6. The apparatus of claim 1 further comprising means
for indicating the amount of recording tape wound on said take-up
reel as a function of said sensed rotational periods and at least
selected ones of said particular characteristics.
7. In apparatus for recording and/or reproducing
information on recording tape transported between supply and take-up
reels, the combination comprising tape drive means for driving said
tape from one to the other of said reels at a predetermined speed,
sensing means for sensing the rotational periods of said supply and
take-up reels while said tape is driven at said predetermined speed,
the rotational period of said supply reel being represented as Ts
and the rotational period of said take-up reel being represented as
Tt; means for storing predetermined constants associated with
respectively different types of tapes; means for reading out
selected ones of said stored constants as a function of said sensed
rotational periods; and means for indicating the amount of tape
wound upon one of said reels as a function of said sensed rotational
periods and said read out constants.
8. The apparatus of claim 7 wherein said means for
indicating comprises means for obtaining a signal .alpha.2 representing
27

(Tt/Ts)2, and means for deriving the signal TR=P/(1+.alpha.2) + Q,
wherein P and Q-are constant values determined by the minimum
diameter of the supply or take-up reel when none of said recording
tape is wound thereon, by the total length of said recording tape,
and by the predetermined speed at which said tape is driven, and
wherein TR represents the remaining amount of said tape wound on
said supply reel.
9. The apparatus of claim 8 wherein said means for
deriving comprises central processing means including an arithmetic
section programmed to add unity to the signal .alpha.2 to produce the signal
1 + .alpha.2, to divide a signal P by said signal (1 + .alpha.2), and to add a
signal Q to the quotient P/(1+.alpha.2); and memory means for storing the
signals P and Q associated with the tape being used.
10. The apparatus of claim 9 wherein said stored signal
P represents (.beta.2 + 1)/(.beta.2-1)K, wherein
<IMG>
and K = L/V, and said stored signal Q represents K/.beta.2 - 1; Do being
the minimum diameter of said supply or take-up reel when none of
said recording tape is wound thereon, .delta. being twice the thickness
of said recording tape, L being the total length of said recording
tape and V being the predetermined speed at which said tape is
driven.
11. The apparatus of claim 1 or 7 wherein said sensing
means comprises respective indicia means rotatable with said supply
and take-up reels; and detecting means disposed at respective refer-
ence positions for detecting said rotatable indicia means.
12. The apparatus of claim 11 wherein each indicia
means comprises a rotatable member and a plurality of magnetic
elements spaced uniformly in a circular array about said rotatable
28

member; and wherein said detecting means comprises a respective
magnetic sensor for generating a pulse signal in response to each
magnetic element which rotates therepast.
13. The apparatus of claim 8 wherein said means for
reading out selected ones of said stored constants comprises means
for obtaining a signal representing <IMG>, and means for using
said signal representing <IMG> to read out the stored constants
P and Q from a location in said storing means associated with said
signal representing <IMG>.
14. The apparatus of claim 7 wherein said means for
indicating the amount of tape wound upon one of said reels indicates
the amount of recording time remaining on said recording tape; and
further comprising presettable time indicating means for indicating
a preset desired amount of recording time, comparison means for
comparing the preset time to said remaining time, and alarm means
for providing an alarm indication when said preset time exceeds said
remaining time.
15. The apparatus of claim 7 further comprising display
means for displaying said indicated amount of tape wound upon said
one reel.
16. In apparatus for recording and/or reproducing
information on recording tape transported between supply and take-up
reels of equal reel hub diameter, the combination comprising tape
drive means for driving said tape from one to the other of said
reels at a predetermined speed; sensing means for sensing the
rotational periods of said supply and take-up reels while said tape
is driven at said predetermined speed, the rotational speed of said
supply reel being represented as Ts and the rotational period of
said take-up reel being represented as Tt; means for obtaining a
signal representing <IMG>; means for indicating predetermined
identifying characteristics of said recording tape, including the
total overall length therof, as a function of said signal represent-
ing <IMG>; means for obtaining a signal .alpha.2 representing
29

<IMG>; and means for indicating the remaining amount of tape
wound upon said supply reel as a function of said signal a2 and
selected ones of said indicated predetermined identifying character-
istics.
17. The apparatus of claim 6 wherein said means for
indicating predetermined identifying characteristics of said
recording tape comprises memory means having a plurality of
storage sections each associated with a respective signal represent-
ing <IMG>, each storage section storing a representation of
total overall length, a signal P and a signal Q, wherein the signal
P represents (.beta.2 + 1)/(.beta.2 - 1)K and the signal Q represents K/.beta.2 - 1,
with
<IMG>
K = (L/V), Do is said reel hub diameter, .delta. is twice the thickness
of said recording tape, L is the total length of said recording
tape and V is the predetermined speed at which said tape is driven;
and means for addressing the storage section associated with the
signal representing <IMG>.
18. The apparatus of claim 17 wherein said means for
indicating the remaining amount of tape wound upon said supply reel
comprises arithmetic means for deriving the signal <IMG>,
wherein P and Q are read from the storage location addressed by
said signal representing <IMG> and TR represents the remaining
length of said tape.
19. The apparatus of claim 17 further comprising
display means for displaying the total overall length read from
the storage section addressed by said signal representing <IMG>.

20. The apparatus of claim 18 further comprising display
means for displaying the derived signal TR.
21. A method of displaying the total overall length of a
recording tape that is transportable from a supply reel to a take-up
reel, comprising the steps of driving said tape at a constant speed
for a predetermined time duration irrespective of the amount of tape
that is wound upon said take-up reel; sensing the respective rotations
of said supply and take-up reels; determining the rotational period
Ts of said supply reel in response to the sensed rotation thereof and
determining the rotational period Tt of said take-up reel in response
to the sensed rotation thereof; storing respective indications of the
total overall lengths of different recording tapes on the basis of
the determined rotational periods Ts and Tt of the supply and take-
up reels for said different recording tapes, and displaying the
indication of total overall length that is associated with rotational
periods Ts and Tt which have been determined.
22. A method of displaying the unknown amount of
recording tape which is wound upon a supply reel, comprising the
steps of driving said tape at a constant speed from said supply
reel to a take-up reel for a predetermined time duration; sensing
the respective rotations of said supply and take-up reels; determining
the rotational period Ts of said supply reel in response to the
sensed rotation thereof and determining the rotational speed Tt of
said take-up reel in response to the sensed rotation thereof;
producing a signal .alpha.2, wherein <IMG>; storing constant
signals P and Q, wherein P is a function of the hub diameter of
said supply reel, the thickness of said tape, the overall length
of said tape, and the constant speed at which said tape is driven,
and Q is a predetermined fraction of P, comprising the steps of
storing a plurality of groups of P and Q signals, each group being
formed of a single P signal and a single Q signal associated with
a corresponding value <IMG>, selecting the one group of P and
Q signals which is associated with the determined rotational periods
Ts and Tt; and displaying a signal TR, wherein <IMG>.
31

Description

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3~2
BACKGROUND O~ THF~ INVENTION
This invention relates to a method and apparatus for
determining predetermined characteristics of a reel-to-reel
recording tape, such as the total overall recording capacity
of that tape, and also for determining the remaining recording
capacity of that tape even i~ an unknown quantity of tape already
has been transported from its supply reel to its take-up reel.
In many types of recording/reproducing devices, such
:
as video tape recorders-(VTRIs), audio tape recorders, and the
like, various types of recording tapes can be used therewith.
Typically, such tapes are housed wi`thin a cartridge and are.
transported, duri.ng a record~ng/reproduci~ng operation, from a
supply reel to a take-up reel~ Usually, when a tape cassette
first is loaded onto the recording/reproducing device, the user
is cognizant of the overall recording capacity of that tape
(e.g. thirty minutes, one hour, two hours, three hours, and the
like), and often the tape is fully rewound onto its supply reel
before using. As recording/reproducing proceeds, an indicator,
such as a digital counter, prov~des an ind~cation as to the
amount of tape whi`ch has ~een transported to the ~ake-up reel
or, alternatively, the.amount of tape which rema;~ns on the supply
reel. These indicat~ons provide the user ~ith useful in.~ormation,
for example, as to wh.ether there is sufficient tape remaining
to complete the desired recording operation
There are, however, instances wherein an unknown tape
cassette is loaded onto the recording~reproducing devi~ce~ I~
the user wishes to know the type o~ cassette which has been
loaded into the device, that is, if the user wishes to know the
total overall recording capacity of that cassette, it is necessary
to unload the cassette from the recording/reproducing device~
.

~ ~3~
In ~ome applications, it may be preferred not to unload the cas-
sette, determine its type and then re-load the cassette backinto
the device. For example, in a VTR of the type which withdraws a
length of tape from the cassette and deploys that withdrawn tape
about a recording drum, the exact location of the tape which is
5 positioned ~or recording may not be the same following the re-
load operation as was previously positioned. This may be partic-
ularly detrimental during an edit operation.
Furthermore, if a tape cassette that has been partially
usedr that is, some amount of tape already has been used for re-
0 cordi`ng/reproducing, i6 loaded into the device, an accurate in-
dication of the amount of tape remaining on the supply reel, or
the amount that already has been wound upon the take-up reel,
cannot be readily obtained. It may be necessary first to rewind
the tape completely to its initiall start position, and then to
15 advance the tape to the location at which it had been loaded in-
to the device. ~he usual digital counter, if reset after the
tape had been fully rewound, then wil;L indicate either theamount
of tape which remains ~or recording or the amount of tape which
has been used. It is appreciated that this is a time-consu~ing
20 and annoying task. Nevertheless, it often is the only technique
by which a user can be apprised of the amount of tape which re-
mains for recordingO
It has been proposed, in United States Patent No.
4,232,371, Issued November 4, 1980, ~o indicate the amount of
25 tape which remains on a supply reel in a cassette used in a VTR,
even if an unknown quantity of tape already has been used. How-
ever, in this proposal, the determination of the amount of re-
maining tape is based upon sensing the angular velocity of the
supply reel as that reel rotates when tape is withdrawn from the
30 cassette and loaded onto
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~,

~33~2
the VTR recording apparatus. During this tape-loading operation,
which is to be distinguished from a tape transporting operation
wherein tape is driven from the supply reel to the take-up reel,
the take-up reel is held stationary. Also, in this proposed
technique, there is no su~gestion of determining automatically
the type of cassette which is used, that is, the total overall
recording capacity of that cassette.
OBJEC~S OF THE INVENT ION
Therefore, it is an object of the present invention
to provide an improved method and apparatus for indicating auto-
matically predetermined characteristics, such as the total overall
recording capacity, of a recording tape, regardless of the amount,
if any, of tape which has been wound from its supply reel to its
take-up reel.
Another object of this invention is to provide a method
and apparatus for indicating automatically the amount of tape
which remains for a recording operation regardless of the arbi-
; trary quantity o~ tape which already may have been wound fxom
the supply reel to the take-up reel thereof.
Yet another object of this invention is to provide an
improved method and apparatus for indicating predetermined charac-
teristics of a reel-to-reel tape, and for indicating the amount of
such tape which remains for a recording/reproducing operation,
regardless of the arbitrary quantity of tape which already may
have been usedO
A still further object of this invention is to provide
an improved method and apparatus for indicating the type and quan-
tity of tape which is used in a recorder/reproducer, which over-
comes those problems and disadvantages mentioned hereinabove.

~ ~33~
A still further object of this invention is to provide
a method and apparatus for indicating the amount of tape which
remains for a recording/reproducing operation, even if particular
characteristics of the tape, such as its total overall recording
capacity, are not known.
Another object of this invention is to provide apparatus
for use in a recorder/reproducer of the type wherein tape is trans-
ported from a supply reel to a take-up reel, to indicate automati-
cally the total overall recordi`ng capacity of that tape and,
moreover, to indicate the quantity of tape which remains available
for recording/reproducing during an initial, or preliminary opexa-
tion of the recorder/reproducer.
Various other objects, advantages and features of the
present invention will become readily apparent from the ensuing
detailed description, and the novel features will be particularly
pointed out in the appended claims.
.. .. : . ....
SUMM~RY OF THE INVENT ION
In accordance with this invention, a method and
apparatus are provided for indicating predetermined characteris-
tics, such as the tatal overall capacity, of a recording tapewhich is transportahle at a predetermined speed from a supply
reel to a take-up reel. The respective rotati`ons of the supply
and take-up reels are sensed, and the rotational periods Ts and Tt
of the supply and take-up reels, respect~vely, are determined.
Predetermined characteristics of the recordi~ng tape are indi~cated
as a function of the determi`ned rotational periods. For example,
representations of different recordi`ng capaci:ties are stored,
each stored represen-tation being associated with a respecti~e
signal representing Ts2 -~ Tt2. The stored representa~ion which
is associated with the determined rotational periods Ts and ~t
--4--

~33~Z
i~ selected and displayed. In accordance with anokher aspect
of this invention, the amount of tape wound upo~ ~he supply
; (or take-up) reel is indicated as a unction of the determined
rotational periods Ts and Tt and also selected characteristics
which are inherent in thç tape. ~n this regard, ~he r~maining
recording capacity TR f the tape wound on the supply reel is
determined in accordance with the expression TR = ~-~a~2 ~ Q~
wherein P and Q are constant values associated with the tape
which is used, these values being determined by the diameter
of the hub of the supply reel, the total length of khe recording
tape, the thickness of ~he tape and the predetermined speed at
which the tape is driven; and c~2 c (T~/TS)2. Sign~ls represent-
i~g P and Q associated wi~h each value ~TS2 + Tt2) are stored,
and the proper P and Q signals are se:Lected for use in the a~ove
equation as a function of the detesmined rotational periods of
th~ supply and take-up reels. The s~nal representing TR may be
d~splayed.
More particularly, there is provided:
In apparatus for recording and/or reproducing
information on recording tape transported between supply and take-
up reels, the combination comprising tape drive means for driving
; said tape from one to the other of said reels at a predetermined
speed; sensing means for sensing the rotational periods of said
supply and take-up reels while said tape is driven at said predeter-
mined speed, the rotational period of said supply reel being repre-
sented as Ts and the rotational period of said take-up reel being
represented as Tt; means for determining the overall length of said
recording tape as a function of said sensed rotational periods;
means for storing particular identifying characteristics associated
with tapes of different lengths; and means for indicating selected
ones of said stored characteristics in accordance with said sensed
rotational periods.
. s '~ ,?
~ ` 5-

~333L~Z
There is also provided:
In apparatus for recording and/or reproducing
information on recording tape transported between supply and take-up
reels, the combination comprising tape drive means for driving said
tape from one to the other of said reels at a predetermined speed;
sensing means for sensing the rotational periods of said supply and
take-up reels while said tape is driven at said predetermined speed,
the rotational period of said supply reel being represented as Ts
and the rotational period of said take-up reel being represented as
T~; means for storing predetermined constants associated with
respectively different types of tapes; means for reading out
selected ones of said stored constants as a function of said sensed
rotational periods; and means for indicating the amount of tape
wound upon one of said reels as a function of said sensed rotational
periods and said read out constants.
There is also provided:
In apparatus for recording and/or reproducing
in~ormation on recording tape transported between supply ahd take up
reels of equal reel hub diameter, the combination comprising tape
drive means for driving said tape from one to the other of said
reel~ at a predetermined speed; sensing means for sensing the
rotational periods of said supply and take-up reels while said tape
is driven at said predetermined speed, the rotational speed of said
supply reel being represented as Ts and the rotational period of
said take-up reel being represented as Tt; means for obtaining a
signal representing Ts2 + Tt2; means for indicating predetermined
identifying characteristics of said recording tape, including the
total overall length therof, as a function of said signal represent-
ing TS2 + T~2; means for obtaining a signal ~2 representing
3~ ~Tt/TS)2; and means for indicating the remaining amount of tapewound upon said supply reel as a function of said signal a2 and
selected ones of said indicated predetermined identifying character-
istics.
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~33~
There is urther provided:
A method of displaying the total overall length of a
recording tape that is transportable from a supply reel to a take-up
reel, comprising the steps of driving said tape at a constant speed
for a predetermined time duration irrespective of the amount of tape
that is wound upon said take-up reel; sensing the respective rctations
of said supply and take-up reels; determining the rotational period
Ts of said supply reel in response to the sensed rotation thereof and
determining the rotational period Tt of said take-up reel in response
to the sensed rotation thereof; storing respective indications of the
total ~verall lengths of different recording tapes on the basis of
the determined rotational periods Ts and Tt of the supply and take- -
up reels for said different recording tapes, and displaying the
indication of total overall length that is associated with rotational
periods Ts and Tt which have been determined.
BRIEF DESCRIPTION ~F THE DRAWIMGS
.
The following detailed descrip~ion, given by way of
example, will best be understood in conjunction with the accom-
21 panying drawings in which;
FIG. 1 illustrates one application of the preseninvention in the environment of a VTR;
FIG. 2 represent~ the manner in which the present
invention is us~d either i~ a VTR or in an audio recording systcm;
2~ FIGS. 3 and 4 are useful in explaining t~e underlying
principle of the presen invention;
FIG. 5 is a graphi~al representation which i5 useful
in under~tanding the present invention; and
, .
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:~"~

~3~
FIG. 6 is a flow diagram representing the manner in
which indications as to type and availa~le capacity of the
recording tape are determined.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
-
As will become apparent from the following detailed
description, the present invention ~inds ready application either
in a video tape recorder of the type in which a loop of magnetic
recording tape is withdrawn from a cassette housing and deployed
about a recording~reproducing drum/ or in an audio tape recorder
wherein recording tape merely is transported from a supply reel
to a take-up reel past a recording/reproducing head. In both
types of recorders, the tape is driven at a substantially constant
speed by the combination of a capstan and pinch roller, as is
well known~ Depending upon the type of recorder, this transport
speed is fixed and constant. Furthermore, in the following dis-
cussion, it is assumed that the tape is housed within a cassette.
Alternatively, in both the VTR and audio recorder applications,
the tape may be transported in simple reel-to-reel arrangements
in the absence of a cassette or cartridge.
Turning now to FI~. 1, there is illustrated a t~pical
embodiment of a VTR in which the present invention can be used.
This VTR includes a guide drum 10 adapted to receive a portion
of magnetic tape 4 deployed thereabout and having a pair of
rotary transducers, or heads 15, 16 for scanning successive
parallel tracks across the tape which is deployed about the
drum. The VTR is adapted to receive a tape cartridge 1 which
contains a supply reel 2 and a take-up reel 3 for transporting
tape 4 therebetween. The VTR further includes a tape-loading
mechanism schematically illustrated as comprising a circular
support ring 5 which extends around drum 10 and which is supported

3~L~2
for rotation on various guide rollers. The VTR further includes
a tape-loading mechanism comprised of a pivotal arm 7 and a tape-
engaging pin 8, as well as various pins or rollers 6 which extend
upwardly from support ring 5. Pins or rollers 6 are adapted to
move with the support r;ng during a loadin~ and unloading operation
so as to guide tape 4 about guide drum 10O
When cartridge, or cassette 1 first is positioned, or
loaded, into the VTR, pivota]. arm 7 is dis~osed in the position
represented by the ~roken lines such that tape guiding pin 8
th~reon extends upwardly into an opening normally provided on
the housing of cassette 1 so as to be positioned within the
housing and behind the run of tape 4. When a loading operation
is carried out, pivotal arm 7 pivots to the pOSItiOn represented
by the solid lines, thereby withdrawing a portion of tape 4
from cassette 1. This portion of w.ithdrawn tape also engages
an adjacent pin or roller 6 which is proximate pivotal arm 7.
Then, support ring 5 rotates in the counterclockwise direction
so as to pull tape 4 from cassette 1 and then to deploy this
withdrawn tape about a portion o~ the periphery o~ ~uide drum 10.
20 . A pinch.roller 14 is rotatably mounted on support ring 5; and
when this- support ring IS fully rota~ed to its loadea position,
as illustrated in ~'IG. 1, the pinch roller is brought into contact
with a capstan 13, the latter being ixedly supported in the ~TR.
Hence, capstan 13 and pinch roller 14 capture tape 4 therebetween
such that as the capstan is dri~en, tape 4 is transported at a
constant speed in the direction indicated by the arrows. The run
~ollowed by tape 4 in response to the operation of capstan 13
and pinch roller 14 traverses an erasing head 9, an aud~o erasing
head 11 and an audio recording/playback head 12. Thus, erasing
head 9 serves to erase video signals from tape 4, erasing 11
--7--

~3L33:~L2~
serves to erase audio signals from the tape and head 12 serves
to record or play back audio signals during a recording or
reproducing mode, respectively. As tape 4 is driven in the
direction indicated by the arrows about the loop from supply
reel 2 to take-up reel 3, gulde drum lO rotates in the direction
indicated ~y the arrow such that heads 15 a~d 16 scan successive,
parallel, skewed trac~s across the width of tape 4. During a
recording operation, heads 15 and 16 serve to record video signals
on the tape. During a reproducing operation, previously recorded
video signals are played back.
In accordance with one aspect of the present invention,
if cassette 1 is loaded into the VTR, but the type of cassette
is not known, that is, the total overall recording capacity of
that cassette has not been ascertai~ned, such total overall
recording capacity can, nevertheless, be indicated automatically.
This indication is prov;ded regardless oE whether a fresh cassette
is loaded into the VTR, that is, regardless of whether all of
tape 4 is wound initially on supply reel 2, or whether an unknown
quantity of tape aiready has been transported and wound onto take-
up reel 3. In accordance wit~`another aspect of t~is invention,even if an arbîtrary amount of tape is wound upon take-up reel 3,
the recording capacity o~ the remainin~ amount of tape that is
wound on supply reel 2 can be indicated automati`cally.
Referring now to FIG. 2, the elements which are used
to indicate the type o~ tape and the amount or recordin~ capacity
thereof are illustrated~ FIG. 2 merely shows tape 4 transported
from supply reel 2 to take-up reel 3 v~a the combination of
capstan 13 and pinch roller 14. This tape transport apparatus
therefore may be included in the VTR arrangement shown in FIG. 1
or, alternatively, may be included in an audio recorder/reproducer

~33~2Z
of conventional type. In either em~odiment, the type of cassette
which is used, that is, the total overall recording capacity of
that cassette, as well as the remaining amount of tape w~ich is
wound upon supply reel 2, are indicated automatically.
The illustrated apparatus includes a central processing
unit (CPU) 22, which may comprise a microprocessor, a micro-
computer, or the like, that is supplied with pulses which repre-
sent the rotational periods of the supply and take-up reels,
respectively. CPU 22 is adapted to process t~ese pulses and,
based thereon~ to determine the type (e.g. total overall recording
capacity) of tape which has been loaded onto the VTR (or the audio
recorder/reproducer) and also to determine the remaining recording
capacity of that tape. CPU 22 is coupled to a display de~ice 29
which is adapted to display t~e determ;ned type and remainln~
recording capacity of tape 4. The CPU additionally includes
another input connected to a presettable timer 21, the latter
being adapted to be preset to represent the requi~site recording
time for completing a parti~cular recording task. CPU 22 is
adapted to compare this preset rec~rd;ng time to the determined
remaining recording capacity of tape 4 to ascertain whether there
is sufficient recording capacity to complete the desired operation.
The output of CPU 22 is connected to an alarm device 30 which is
operated, or triggered, in the event that the determined remaining
recording capacity is less than the desired capacity, as represented
by preset timer 21.
The aforementioned pulses which are supplied to CPU 2Z
to repres~ent the rotational periods of supply reel 2 and take-up
reel 3 are generated by detecti`ng arrangements 23 and 24. Detect-
ing arrangement 23 is comprised of a rotatable member, such as
disc 19, secured to reel mount 17 of supply reel 2. Rotatable

~33~LZ~
member 19 thus is rotatably dri~en when supply reel 2 rotates
to pay out tape 4. A circular array of magnetic elements 25
is provided on the periphery of rotatable member 19. A pick-up
sensor 26, such as a magnetic pick-up head, is fixedly positioned
relative to rotatable member 19 so as to detect each magnetic
element 25 as that element rotates therepast. Sensor 26 generates
a pulse in response to the passage of each magnetic element 25.
Sensing arrangement 24 is of similar construction and
is comprised of a rotatable member, or d~sc 20, that is secured
to reel mount 18 of take-up reel 3. A circular array of magnetic
elements 27 is provided on the periphery oE rotatable member 20;
and a pick-up sensing head 28 i`s positioned so as to detect each
magnetic element that rotates therepast and to generate a corre-
sponding-pulse. The pulses generated by pick-up sensors 26 and
28 are supplied to CPU 22.
It may be appreciated that, if desired, rotatable
members 19 and 20 may be ~echanically coupled to supply and
take-up reels 2 and 3, respect;`~ely, by other suitable trans-
missions so as to be rotatable w~th these reels.
2Q ~f each rotatable member 19, 2Q is provided with, for
example, eight individual magnetic elements 25, pick-up sensor
26, 28 generates eight pulses for each single rotation of the
rotatable member. The rotational speed of supply reel 2 or take-
up reel 3 can be determined by div~din~ the number of pulses
which are generated by pick up sensor 26, 2~ by the time duration
during which tape 4 is driven. For example, if forty pulses are
generated during a two second inter~al, then the frequency of
these pulses is equal to twenty-pulses per second. Since eight
pulses are generated during each rotation, the an~ular velocity
of the rotatable member is seen to be 20/8=2.5 rotations per second.
--10--

~33~2~
Of course, the rotational period of the disc is the reciprocal
of the angular velociky thereof which, in the present example,
is equal to 1/2.5 = 0.4, or 400 msec. CPU 22 functions in a
manner that ls clearly appreciated by one of ordinary skill in
the art to determine the rotational periods Ts and Tt of supply
reel 2 and take-up reel 3, respectively, in response to the
pulses which are generated by pick-up sensors 26 and 28.
In operation, let it ~e assumed that the cassette is
properly loaded onto the VTR or audio recorder~reproducer with
which tape 4 is to be used. This means that, for the application
of the present invention to a VTR, tape 4 is deployed about the
VTR guide drum in the manner illustrated in F~G. 1. Once the
cassette is properly loaded, the tape transport mechanism (not
shown) is operated for a predetermined time duration, on the
order of a few seconds. ~ence, during this time duration, tape 4
is driven by the combination of capstan 13 and pinch roller 14
~rom supply reel 2 to take-up reel 3. As the tape ~s driven in
this manner, supply reel 2 rotates to pay out the tape; and take-
up reel 3 also rotates to wind up the tape. Rotatable members
19 and 20 rotate w~th supply and take-up reels 2 and 3, thereby
moving magnetic elements 25 and Z7 past pick-up sensors 26 and
28, respectively. Consequently, pulses are supplied to CPU 22
from pick-up sensors 26 and 28, the respecti~e frequencies o
these pulses being a function of t~e rotational velocity, or
speed, of the supply and take-up reels. CPU 22 processes these
pulses to produce signals, such as digital signals, representing
the rotational period Ts of supply reel 2 and the rotational period
Tt of take-up reel 3. These signals representing the rotational
periods of the supply and take up reels are used to determined
the total overall length, or recording capacity, of tape 4.
--11--

~L33~2~
This overall length, or recording capacity, is determined
irrespective of the arbitary amount of tape which may have
been wound upon take-up reel 3 at the time that the cassette
was loaded onto the VTR or audio recorder/reproducer. For
example, if twenty m;nutes worth of tape initially had been
wound upon take-up reel 3, and if the total overall recording
capacity, or length, of tape 4 is equal ~Q three hours, CPU 22
will determine that, during the initial transport ~f tape 4 rom
supply reel 2 to take-up reel 3/ the tape has an o~erall length
capable of recording up to three hours. That is, CPU 22 will
determine that tape 4 is a so-called three-hour recording tape,
even though twenty minutes of recording time has been used. CPU
22 also will determine the amount of tape remaining on supply
reel 2. In a prefexred emhodiment, CPU 22 will control display
device 29 to display that two hours, forty minutes of tape remains
on supply reel 2. This display is provided even though, initially,
the quantity of tape which had Been wound upon take-up reel 3 had
not been known~
Let i~ be further assumed that, initially, although
the user had not been cognizant of the amount of tape remaining
on supply reel 2, tlmer 21 had ~een preset to, for example, two
hours, forty~five minutes. In the presently assumed ~xample, CPU
22 determines that only two hours, orty minutes of tape is wound
upon supply reel 2. Hence, since the preset time entered into
timer 21 exceeds the actual amount of tape remain~ng on supply
reel 2, CPU 22 triggers alarm 30 to indicate this situation.
After the predetermined time duration has expired,
that is, the duration during which tape 4 is transported from
supply reel 2 to take-up reel 3 so that CPU 22 can determined
the characteristic type of tape which is used, and also can

:
33L~2
determine the amount of tape remaining on supply reel 2, that
portion of tape which had been payed out from the supply reel
is rewound thereon. Thus, following the initial operation during
which the type and available quantity of tape are determined,
the tape is returned to its init.ial position so that a recording
or reproducing operation then can proceed. Thus, tape is not
"wasted" during this initial operation. That is, the useful
quantity of tape which is available ~s not reduced by reason
of this initial operation.
.10 The manner in which the characteristic type of tape 4
can be determined mathematically now will be described with refer-
ence to FIGS. 3 and 4. Let it ~e assumed that th.e diameter of
the hub of supply reel 2 is equal to the diameter of the hub o~
take-up reel 3, and is represented as Do. Let it be further
assumed that when all of tape 4 is wound upon, for example, supply
reel 2, the total diameter o~ the outer coil o~ tape wound thereon
is represented as Dm. Now, if the total, over~ll Length.of tape
4 is equal to L, and i~ t~e thickness of the tape is represented
: as ~/2, then the amount of tape which is wound upon a fully-
loaded supply reel can be expressed as:
1r m - ~ o = L
Dm2 = Do2 + 2~ L/~
If tape 4 then runs from supply reel 2, in its fully loaded
condition, to take-up reel 3, after some amount of time, a
quantity of tape is wound upon the take-up reel~ as illustrated
in FIG. 4. For the condition shown in FIG. 4, it is assumed that
the diameter of the outermost coil of tape wound upon supply
reel 2 is represented as Ds, and the diameter of the outermost
-13-

~L3~
coil of tape wound upon take-up reel 3 is repres.ented as Dt..
Of course, as is known, the angular velocity of each reel is a
function of its reel diameter. Nevertheless, since ît is assumed
that tape 4 is driven ~y a capstan, the velocity V of the tape is
constant, as determined by the capstan speed. The rotational
period of, for example, take up reel 3 is equal to the time required
for one rotation thereof. Duri`n~ this period, tape 4 is, of
course, driven at the linear velocity V, and the length of tape
which is wound upon the take-up reel is equal to the circumference
thereof. Hence, the rotational period Tt of take-up reel 3 can
be expressed aso ~D
Tt V (2)
Similarly, the rotational period Ts of supply reel 2 can ~e
expressed as:
s V (~3)
Let it be assumed that m turns, or coils, of tape 4
are withdrawn from supply reel 2, and that n turns, or co~l.s,
of tape are wound upon ta~e-up reel 3 in the arbitrary example
shown in FIG. 4. With respect to t~e ta~e-up reel, t~e diameter
of the first turn thereon ;s~ equal to Do/ the diameter of the
: take-up reel hub. The d~ameter of the second turn.i~s equal to
Do + ~ , the diameter of the take-up reel hub plus twice the
thickness of the tape. The d;ameter o~ the th;~rd turn is equal
to Do + 2 ~ . Therefore, it can be appreciated that the diameter
of the nth tur~ is equal to
Dt = Do + (n-l)~ (4)
With.respect to supply reel 2, i~ no turn had been wlthdrawn
therefrom, the diameter of the supply reel would be equal to Dm.
If one turn is withdrawn, the diameter of the supply reel is equal
to Dm ~ S ~ If two turns have been withdrawn, the di~ameter of
~14-

~33~:~2
the supply reel is equal to Dm ~ 2 ~ . If m turns are withdrawn
from the supply reel,then lts diameter can be expressed as
Ds = Dm ~ m ~ (5)
Since the entire length L of tape 4 is not changed/ the diameters
Ds and Dt of the supply and take up reels exhibit the following
relationship with respect to the maximum and minimum diameters
Dm and D~:
Ds + Dt = Dm ~ Do (6)
The expression Dm2 ~ Do2 is constant and is dependent
solely upon the characteristics of the particular tape cassette
which is used. That is, this expression depends upon the diameter
of the supply (or take-up) reel hub and the diameter of the fully-
loaded supply (or take-up) reel, the latter being dependent upon
the thickn~ss and length of the tape which is used. Thus, from
equation (6), it is seen that, regardless o the amount of tape
which is wound upon the supply and take-up reels, the expression
D 2 + Dt2 is fixed and is constant for the particular cassette
s r--
which is used. FIG. 5 represents the locus of ~ Ds ~ Dt as
the values for DS and D~ ~ary between maximum diameter Dm and
the minimum diameter Do. If the a~scissa in the graphical depic-
tion of FIG. 5 represents the diameter ~s of the supply reel, and
- if the ordinate represents the diameter Dt of the take-up reel,
then this locus moves in the counterclockwise direction from the
point where Ds = Dm to the point where Dt = Dm. That is, this
locus advances in the counterclockwise direction as tape 4 is
transported from supply reel 2 to take-up reel 3.
It is, of course, appreciated from equation (6) that
= ~ The radius of the circular arc,
shown in FIG. 5, thus is constant for a particular cassette.
Preferably, the different types o cassettes which can ~e used

~L~3~ 2
with the recording/reproducin~ apparatus (i.e., the YTR or the
recorder/reproducer) are standarized as to the diameter of the
supply (or take-up) reel hub, the thickness of the tape, the
length of the tape and the maximum diameter of a fully wound
reel. For convenience, Table I below identifies four different
types of cassettes. It should be readily appreciated that, if
desired, additional types of cassettes may be employed, each
additional type having specified characteristics, that is, a
specified reel hub diameter, tape th~ckness,tape length and
maximum reel diameter:
Ta~le I
Tape CassetteDO~mm) S/2(~ m)L(m) Dm(mm) ~Dm ~Do
Type I 51.8 Z042 61.3 80.3
Type II 51.8 2078 68.3 85.7
Type III 30.0 20150 68.7 75.0
Type IV 30.0 14222 69.7 75.9
It should be recognized that, once the values of Ds and Dt are
determined, regardless of the amount of tape whi ~ ound
on the supply or take-up reels, the expression ~ Ds2 ~ Dt2 .is
established. Since thi.s expression is equal to the expression
Dm2 + Do~, it is seen that the type of cassette which has
:~ been loaded into the recording/reproducing apparatus can be
identified. As an example, CPU 22 may include a memory device
having a plurality of addressable storage compartments, each
: 20 storage compartment having stored therein the particular charac-
: teristics of a corresponding type of cassette. For example,
storage compartment I may store information concerning the reel
hub diameter Do~ tape width, tape length and maximum diameter Dm
associated with cassette Type I, as specified in Table I. The
address of this storage compartment is identified by the
-16-

expression ~ Dm ~ Do associated with cassette Type I. Similarly,
let it be assu~ed that sto.rage compartment II has stored therein
information as to the particular characteristics associated with
cassette Type II, as indicated in Table I. This storage compart-
ment is addressed by the appropriate value of ~ Theremaining storage compartments likewise have stored therein in-
formation relating to the particular characteristics of the other
types of cassettes. Thus, when the values Ds and Dt are determined
by CPU 22, the appropriate.storage compartment is addressed and
the characteristi.cs of the.type of cassette which is associated
with the determined Ds and Dt are read out. Thus, after tape.4
has been transported for some predetermined time duration from
supply reel 2 to take-up reel 3, the pulses supplied to CPU 22
from pick-up sensors 26 and 28 resul~ in the reading out and
display either of the type of cassette which is being used or,
at least, the overall tape length or recording capacity of that
cassette.
It now w~Ll be 2escri~ea how the type o~ cassettet or
particular characteristics associated with that type.j can be
indicated directly ~rom the determined rotational periods Ts and
Tt o the suppl~ and take-up reels, respectively, without first
de~ermining ~he diameters thereof~ Equat~on (6) can be rewritten
as:
Ds {1 + (Dt~Ds~ ~ =`Dm + Do (7
and let it be further assumed that
Dt~DS =~ (8)
If equation (8) is subst~tuted into equation (7), the.result is
written as
Ds (l~c~ 1 = Dm + Do (9)
-17-

i
331~2
wikh the result that
__
¦D 2 + D
+ ~< ( 10 )
In a similar manner, equations (6) and (8) can be combined to
find the expresslon for the diameter Dt of the take-up reel as
~ollows:
Dt2 ~1 + c~l2) = Dm2 + Do2 (11)
D 2 (1 +C~2) = c~2 (D 2 ~ Do ) ~12)
Dt ~ (13)
If equations (2) and (3) are used in equation (9), the result
appears as:
Dm + Do = Ds (l+C~ r ) Ts (l+C~ )
( V )2 (T 2 +c~2 Ts ) (14)
From equations (2), (3) and (8), the term o~2 TS2 may be rewritten
as c~2 TS2 = Tt2 Thus, equation (14) may be expressed as:
Dm + Do = (~r) ~TS2 -~ Tt ) (15)
and,
2 2 r~ D (16)
It is seen from the foregoing equation that the expression TS2 ~ Tt2
~ is a constant value that is determined only by the specific type
; o tape cassette which is used. This is because the tape speed V
is fixed and, depending upon the type of cassette, as set out in
Table I above, the maximum and minimum reel diameters Dm and Do,
respectively, are fixed.
-18-

~33~Z
Since the rotational periods Ts and Tt may be obtained
directly by CPU 22 in response to the pulses supplied thereto by
pick-up sensors 26 and 28, the expression T 2 ~ Tt2 may be deter-
mined easily. From equation (I6), the determination of khis
expression is indicative of the type of cassette which is used.
Hencef the particular characteristics associated w-ith each type
of cassette, as se-t out in ~able I, may be stored in storage
compartments which are addressed by the determination of TS2 + Tt
That is, once the rotational periods of the supply and take-up
raels are obtained, the type o~ cassette, an~ thus the particular
characteristics of that cassette, is identified. The.expression
TS2 + Tt2 can be used as an address to retrie~e., or read-out,
the particular characteristics whi`ch are inherent in the tape
cassette whose type is ~dent~fied b~ this address.
The mathematical der~vation for indicating the amount
of tape which remains wound on supply reel 2, regardless of the
arbitrary quantity of tape whi`ch.may be wound upon take-up reel 3,
: now will he discussed~. Let .it be ass~ned that this arbitrary
quantity of tape which. is wound upon. take~:up reel 3 ~s represented
as X. This length X is equal to the c~rcumference o~ the ~rst,
or innermost, turn of tape wound upon the take-up reel, plus the
circumference of the second turn, plus the circ~nference of the
third turn, and so on up to the circumference.o~ the nth turn.
It is recalled that -the diameter of the nth turn is equal to
Do + (n~ . Therefore, the amount of tape X which. is wound
upon tak.e-up reel 3 may be expressed as:
X =~ D + ~ (Do+ ~ ) + ~r(Do + 2S ) + ~ + ~Do ( 1)~
- ~ ~nD + n(n~ } (17)
Of course, the amount of tape X which is wound upon the take-up
reel is equal to the amount of tape which has been withdrawn from
-l9-

~3~ ~2
the supply reel. This length of tape which had been withdrawn
from the supply reel is equal to the circumference of the first
outermost turn which had been wound thereon, plus the circumfer-
ence of the next outermost turn, plus the circumerence of the
next turn, and so on, up to the circumference of the mth turn
which had been wound thereon. ~he diameter of the first turn
is equal to Dm ~ J , and the diameter of the mth turn is equal
to Dm ~ m 3 Hence, the length of tape X which had been with-
drawn from supply reel 2 may be expressed as:
X = ~r(Dm ~ ~) f ~ (Dm - 2 ~ ) ~ ~~~~~ + ~ (Dm ~ m ~)
= ~ ¦mD~ ~ ( 2 - sj (18)
From equations (2) and (3), it is known that Dt/Tt = DS/Ts.
Dt thus may be written as
T
Dt = T Ds CX Ds (l9)
The term n may be obtained from equation (4) as
n ~ (20)
and the term m may be obtained from equation (5) as
D - D
m _ m ~ s (21)
Now, since equations (17) and (18) are equal, they specify the
following identity:
n(n-l) ) m(m+l)
~r ~nDO f 2 ~3 ~ ~mDm ~ (22)
If equations (l9), (20) and (21) are substituted into equation
(22), the result appears as
:
2) D 2 + ~1-~ ) S Ds + Do(~ Do) m ~ m (23)
In equation (23), the terms ~ and Ds are not constant. Never-
theless, eauation (23) can be simplified i~ it is assumed that:
_20-

~L~3~2
2 -_ A
(1 -~)~ = B
Do( ~ - Do) t Dm (d Dm)
With these assumptions, equation (23) can be sol~ed for Ps as
; -B + ~s2 _ 4AC
s 2A (24
If the expression for m defined by equation (21) is
substituted into equation (18), the result can be rewritten as:
X = ~S (Dm ~ Ds)(Dm + Ds ~ ) (25)
Of course, Dm ~>S and Ds>~S . Equation (25) thus can be
simplified to
X = 2 (Dm ~ Ds ) (26)
From the foregoin~ assumptions for A, B and C, a close approxima-
tion of equation (24) will be xealized if it is assumed that
B = 0. With this assumption,equation (24) can be rewritten as:
DS2 = -C = O m (27)
Now, if equation (27) is substituted into equation
(Z6), the res~llt appears as:
:
2~ ~ ~ D 2 ~ 2 (28)
In equation (28), ~ is defined as:
~ 2 (Dm)2 Do . ~ ~ (29)
wherein Dm is defined by equation (1).
The time required to transport the entire length L of
tape 4 from the supply reel to the take-up reel is fixed, and is
a function of the constant tape speed V. Let this time be repre-
sented as K wherein
-21-

~L~3~
K = V (30)
Now, the time required to transport that portion of tape 4
which remains on supply reel 2 is referred to as the remaining
time TR, and is indicative of the recording capacity of that
portion of tape 4 which remainsO This remaining time TR ma~ be
expressed as:
T - L-X = K(l- -) (31)
The term X is defined by equation (28) and the term L is defined
by equation (29). When equations (28) and (29) are substituted
into equation (31), this equation is rewritten as:
T { K ~ {1 + ~ (32)
From the foregoing discussion, it is appreciated that ~ and K
are constant values which are established by the particular type
of cassette which is used. Hence, the only variable in equation
~ 15 (32) is the term c~ . In equation (32), let it be assumed that
; ~ K = P; and 2K - Q. With this assumption,
equation (32) may be rewritten as:
T = - P _ Q (33)
R 1 +o~2
Thus, since P and Q are values which are constant for a particular
type of cassette, once the type of cassette is determined, as
discussed above, and once the term d is obtained, the remaining
time TR, that is, the available recording capacity of the tape
which remains on the supply reel, can be indica~ed from equation
(33). This equation can, of course, be implemented in the arith-
metic section of CPU 22.
From equation (8), c~= Dt/DS. From equations (2) and
(3), Dt = VTt/~ , and Ds = VTS/ ~ . Accordingly, e~ may be
expressed as:
Tt
s (34)
-22-

~133~ 2
Of course, CPU 22 readily determines the rotational periods
s and Tt in response to the pulses supplied thereto by pic~-up
sensors 26 and 28, respectively. Hence, in response to these.
pulses, CPU 22 derives the address TS2 + Tt2 o-f equation (16)
from which the particular type.of cassette which is loaded onto
; the recorder/reproducer is determi`ned. Once the type of cassette
is determined, the characteristics inherent in that cassette
likewise are determined'. That is-, the values P and Q, which are
associated with that type of cassette,' are ascertained. CPU 22
calculates the term G~, and retrieves the'stored values o P
and Q which are associated with the cassette that is being used,
the type of this cassette havin~ ~een determined ~y the.calculated
expression TS2 + Tt2. CPU 22 then carrles out the.arithmetical
operation of equation t33) ~o indicate the rema-~nin~ time TR of
tape ~. The determined type of cassette and the calculated remain-
lng time are dIsplayed on display device 29. Furthermore, if
timer 21 had been preset by~-the'user, the preset time is compared
by CPU 22 with the~calculated remaining time rrR. If the remaining
time.~R is less than the:'~esired, preset time, alaxm 30 is ener-
gized.
FIG. 6 illustrates a flow chart representin.g the opera-
tion of CPU 22.. Pulses~which are gen'erated by detectors 23 and
24 are'supplied to the CPU, and the rotat;.onal periods Ts and Tt
are aetermined by the CPU in response to these pulses. The
determinea rotational periods Ts and Tt are square.d to produGe
TS2 and Tt2, and these squared rotational pexiods~are summed to
produce a signal representing t.~e expression TS2 ~ Tt The type
of cassette then LS det'ermined in response to th;~s expression,
as by addres~sing a particular storage compartment which. is asso-
ciated with'this expression. The characteristics stored in. the
-23-

~33~Z~
addressed storage compartment, as ~epresented by, for example,
the characteristics set out in Ta~le I, may be read ou-t;- and
one or more of such characteristics, such as the total overall
length, or recording capacity, is displaved. Also, the addressed
storage compartment may store'signals representing the expressions
P and Q which are associated with the determined type of cassetke.
CPU 22 also determines' the term ~ in response to the
;calculated rotational periods Tt and Ts. This term o~ then is
squared and is summed with'unity. The'arithmetic section of CPU
22 then obtains the quotient of p/(o~2 + l). The value Q is
subtracted from this quotient, resulting in an indication of
the remaining time TR. Th~s indication is displayed on display
device 29 and, moreover, is compared to the preset time that
the user may enter into timer 21. As mentioned abo~er if the
preset time exceeds the remaining time TR, alarm 31 is energized.
` While the present ~nvent~on has been particularly shown
- and described with reference to a preferred embodiment, it should
be readily apparent to those of ordinary skill in the art that
~arious changes and modificati~ons- ~n form and deta~ls may be
made without depart;`ng from the spirit and scope of the invention.
For example, this inVentIon need not be limited sQlely for use
in a reel-to-reel tape cassette.' It is contemplated that the
invention disclosed' h~rein can be used to indicate particular
character~stics and remaining recording capacity of a so-called
open-reel tape. Also, although a VTR has been illustrated, it
is appreciated that this- invention also can be used in an audio
recorder~reproducer to ~dentiv the type of tape which is used
therewith, selected characteristics of that tape and the amount
of recording capacity which'remains. These indications are pro-
v:ided irrespective of the arbitrary amount of tape which may be
_~4_

3~2
wound on the take-up reel at the.timç th.at th.e tape is loaded
into the recorder~reproducer. Also, the manner in which.the
rotation of the supply and take-up reels is detected need not
be limited solely to the magnetic sensing devices illustrated
herein. As an alternative, optical devices, electrostatic
devices, and the like may be used to generate pulses correspond-
ing to the angular velocities of the supply and take-up reels.
It is, therefore, intended that.the appended claims be interpreted
as including the foregoing as well as varlous other such changes
and modifications.
'