 |
Claims  |
|
|
What is claimed is:
1. Apparatus for determining the amount of recording time available on a
videotape cassette; said cassette comprising a casing having interior
confines; first and second reels having floating hubs and being captured
for rotation within said confines; and a length of video recording tape
mounted for transportation between said reels and having respective
portions wound about said hubs; and said apparatus comprising:
a first transparent disc;
a second transparent disc;
a fastener securing said first and second discs in parallel superposed
relationship for rotation of said second disc about an axis relative to
said first disc;
an alignment guide for visually establishing a known reference location of
said first disc relative to one of said hubs, independent of variations of
position of said one of said hubs within said confines;
an index located on a first one of said first and second discs;
a time scale located on a first other of said first and second discs;
a reference line provided on a second one of said first and second discs;
and
a spiral provided on a second other of said first and second discs, said
spiral expanding radially, circumferentially about said axis;
said index, time scale, reference line and spiral being relatively
dimensioned and configured so that rotating said second disc about said
axis relative to said first disc with said known reference location
established, until intersection of said spiral with said reference line
matches an outside edge of an outermost layer of said portion of tape
wound about said one of said hubs, will align said index with said time
scale to indicate the amount of recording time available.
2. Apparatus for determining the amount of recording time available on a
videotape cassette; said cassette comprising a casing having interior
confines; first and second reels having floating hubs and being captured
for rotation within said confines; and a length of video recording tape
mounted for transportation between said reels and having respective
portions wound about said hubs; and said apparatus comprising;
a body member;
a pointer;
a fastener securing said body member and pointer in superposed relationship
for rotation of said pointer about an axis relative to said body member;
an alignment guide for visually establishing a known reference location of
said body member relative to one of said hubs, independent of variations
of position of said one of said hubs within said confines;
an index located on a first one of said body member and pointer;
an incremental scale located on a first other of said body member and
pointer;
a reference indicator provided on a second one of said body member and
pointer; and
a spiral provided on a second other of said body member and pointer, said
spiral expanding radially, circumferentially about said axis;
said index, incremental scale, reference indicator and spiral being
relatively dimensioned and configured so that rotating said pointer about
said axis relative to said body member with said known reference location
established, until intersection of said spiral with said reference
indicator matches an outside edge of an outermost layer of said portion of
tape wound about said one of said hubs, will align said index with said
incremental scale to indicate the amount of recording time available.
3. Apparatus as in claim 2, wherein said body member comprises a first
planar element; said pointer comprises a second planar element; and said
fastener secures said first and second planar elements in parallel
relationship.
4. Apparatus as in claim 3, wherein said first planar element comprises a
first disc; said second planar element comprises a second disc; and said
fastener secures said first and second discs in coaxial relationship.
5. Apparatus as in claim 2, wherein said body member has a first axial
central bore; said pointer has a second axial central bore; and said
fastener comprises means passing through said first and second bores.
6. Apparatus as in claim 2, wherein said alignment guide comprises a
circular visual reference having a center coincident with said axis.
7. Apparatus as in claim 2, wherein said index comprises a reference line
extending radially of said axis; and said scale extends circumferentially
of said axis.
8. Apparatus as in claim 7, wherein said scale comprises a plurality of
markings corresponding to respective increments of available recording
time associated with different radial positions of said outside edge of
said wound portion of tape.
9. Apparatus as in claim 1, wherein said scale comprises a plurality of
scales, each including a plurality of markings corresponding to respective
increments of available recording time associated with said different
radial positions at a different video recording speed.
10. Apparatus as in claim 2, wherein said spiral expands radially,
circumferentially of said axis from an inner point to an outer point; and
said index comprises a first line extending radially of said axis in
radial alignment with said spiral inner point.
11. Apparatus as in claim 10, wherein said alignment guide comprises a
circular visual reference having a center coincident with said axis; and
said spiral inner point is coincident with said circular visual reference.
12. Apparatus as in claim 2, further comprising an enlargement provided on
said body member or pointer to act as a platform for holding said
apparatus on said cassette.
13. Apparatus for determining the amount of recording time available on a
videotape cassette; said cassette comprising a casing having interior
confines; first and second reels having floating hubs and being captured
for rotation within said confines; and a length of video recording tape
mounted for transportation between said reels and having respective
portions wound about said hubs; and said apparatus comprising:
a first planar element;
a second planar element;
a fastener securing said first and second planar elements in parallel
superposed relationship for rotation of said second element about an axis
relative to said first element;
an alignment guide for visually establishing a known reference location of
said first element relative to one of said hubs, independent of variations
of position of said one of said hubs within said confines;
an index located on said second element;
an incremental scale located on said first element and extending
circumferentially of said axis;
a reference line provided on one of said first and second elements and
extending radially of said axis; and
a spiral provided on the other of said first and second elements, said
spiral extending radially, circumferentially about said axis;
said index, incremental scale, reference line and spiral being relatively
dimensioned and configured so that rotating said second element about said
axis relative to said first element with said known reference location
established, until intersection of said spiral with said reference line
matches an outside edge of an outermost layer of said portion of tape
wound about said one of said hubs, will align said index with said
incremental scale to indicate the amount of recording time available.
14. Apparatus as in claim 13, wherein said scale comprises a plurality of
markings corresponding to respective increments of available recording
time associated with different radial positions of said outside edge of
said wound portion of tape.
15. Apparatus as in claim 14, wherein said spiral extends radially,
circumferentially of said axis from an inner point to an outer point; and
said index comprises a first line extending radially of said axis in
radial alignment with said spiral inner point.
16. Apparatus as in claim 15, wherein said alignment guide comprises a
circular visual reference having a center coincident with said axis; and
said spiral inner point is coincident with said circular visual reference.
17. Apparatus as in claim 16, wherein said first and second elements are
first and second discs; and said fastener secures said first and second
discs in coaxial relationship.
18. Apparatus as in claim 17, wherein said scale is provided
circumferentially marginally about said first or second disc corresponding
to said one of said first and second elements; and said scale comprises a
plurality of scales, each including a plurality of markings corresponding
to respective increments of available recording time associated with said
different radial positions at a different recording speed.
19. Apparatus as in claim 18, wherein said one of said first and second
elements is said first disc and said other of said first and second
elements is said second disc.
20. Apparatus as in claim 19, wherein said first or second disc includes a
triangular enlargement provided in a plane of the disc to act as a
platform for holding said apparatus by a thumb on said cassette. |
|
 |
|
 |
Claims |
|
|
|
Description |
|
|
BACKGROUND OF THE INVENTION
This invention relates to a method and apparatus for determining the
recording time available on a videotape cassette; and, in particular, to
an apparatus for determining the remaining recording time on a partially
recorded videotape cassette.
Conventional videotape cassettes, such as VHS format cassettes available
commercially for time-displacement recording of television programs in the
home, comprise rectangular casings within which are protectively housed
fixed lengths of magnetic video recording tape mounted for transportation
between supply and take-up reels, across a video cassette recorder (VCR)
read-write recording head. Such tapes come in T30, T60, T120, T130 and
T160 different tape sizes, respectively corresponding to different 30, 60,
120, 130 and 160 minutes of nominally available recording time. The actual
recording time available on a particular tape is a multiple of the nominal
recording time determined by the recording speed (SP, LP or EP).
There is a problem when you want to record several long programs, such as
full-length movies, on a single tape. If the tape is already partially
recorded, there may not be enough recording time left to get the whole
program. So, either the end will be missed, or the tape will rewind
automatically and begin recording over the first program, depending on the
type of VCR you use. One way to guard against this is to use a new tape
each time you record; but, this wastes tape. Another way is to set the
counter on the VCR and keep track of used and unused tape that way. That
is cumbersome and it is easy to forget to reset the tape counter. A more
convenient way is to be able to determine how much recording time is left,
just by measuring the amount of unrecorded tape left on the supply reel,
or amount of recorded tape taken up on the take-up reel.
Existing ways for measuring the amount of tape on the supply or take-up
reel are unsatisfactory. The cassette housing itself has see-through
viewing ports windows above the reels with markings at radially-spaced
increments, but these are hard to see and do not include time
identifications. Moreover, because the reels are merely captured and not
fixed against translational movement within the cassette housing,
considerable float exists between the reel hubs and the markings, making
such readings inaccurate. Stickers, such as shown in U.S. Pat. No.
4,501,396, can be applied to the windows to improve readability; however,
they do not accommodate the float. Rulers, such as shown in U.S. Pat. No.
4,893,414, exist that can be placed over a window and lined up with the
hub. Such rulers have markings identified by increments of
unrecorded/recorded time associated with corresponding different radii of
tape loaded on the hub. The linear scales on such direct reading devices
are, however, too crowded to be useful in a close case.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method and apparatus
for determining, simply and inexpensively, in a visually, readily
discernable manner, the remaining recording time available on a partially
recorded videotape cassette, based on the amount of unrecorded tape left
on the cassette tape supply reel, or amount of recorded tape taken up on
the cassette tape take-up reel.
In accordance with the invention, apparatus for determining the available
recording time comprises a body member, a pointer movably mounted on the
body member, means for establishing a known reference location of the body
member relative to the hub of a reel of the videotape cassette, and means
for indicating the amount of available recording time in response to
positioning of the pointer to mark the location of the outside layer of
tape then wrapped around the hub on the reel.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is illustrated with reference to the accompanying drawings,
wherein:
FIG. 1 is an exploded view of an embodiment of the apparatus, in accordance
with the principles of the invention, for determining the available
recording time on a videotape cassette; and
FIG. 2 is a top plan view of the apparatus of FIG. 1.
Throughout the drawings, like elements are referred to by like numerals.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 shows apparatus 10, in accordance with the invention, being placed
on a T120 or T130 videotape cassette 11 in a position suitable for
determining the amount of time available for recording on a magnetic video
recording tape 12 mounted on a supply reel having a floating hub 14
captured for rotation within the protective confines of a cassette housing
15. The housing 15, in conventional manner, includes a see-through window
16 through which the amount of tape wrapped around reel 14 can be viewed.
The apparatus 10 comprises a body member in the form of a first transparent
circular disc 17 having an axial central bore 18 and a divided cutout area
20 bisected by a radially-directed linear strip 21 on which is marked a
radial reference line 23. A pointer in the form of a second transparent
circular disc 24 includes an axial central bore 25, and is joined in
coaxial parallel superposed relationship to first disc 17 by a rivet 26
passing through aligned bores 18, 25. Such connection fixes the relative
radial positions of discs 17, 24, while enabling relative rotational
movement about an axis 28.
In accordance with the principles of the invention, apparatus 10 has an
alignment guide for establishing a known fixed positional relationship
between body member 17 and the hub 14. For the embodiment illustrated in
FIGS. 1 and 2, the guide is furnished in the form of a circular visual
reference line 30 having a diameter matching the outside diameter of hub
14 visible through window 16. Line 30 is shown located on disc 24 with its
center coincident with the center of disc 24. Aligning circle 30 with hub
14 will set a positional relationship of body member 17 relative to hub
14, independent of variations of the position of hub 14 within the
cassette 11 relative to window 16. Cutout 20 makes it possible to view hub
14 through only one, rather than two, thicknesses of transparent disc
material. The inner contour of cutout 20 preferably includes a circular
portion 32 viewable within the interior of circle 30 and, preferably,
matching the diameter of one of the inside circular flanges typically
found on the usual hub 14. In this manner, as shown in FIG. 2, alignment
of apparatus 10 with hub 14 can be achieved by aligning the part of hub 14
viewable through cutout 20, annularly between the contour 32 of disc 17
and the circle 30 of disc 24.
For setting the position of pointer 24 relative to body member 17, to
correspond with the radial position of the outside layer 33 of tape 12
relative to hub 14, a spiral line 34 is provided on the face of disc 24.
Spiral 34 expands radially, circumferentially of disc 24 from an inner
point 35 coincident with circle 30 to an outer point 36 coincident with
the circular perimeter of disc 24. The illustrated spiral 34 is configured
so that rotating disc 24 about axis 28, with axis 28 held coincident with
the center of hub 14, will cause the intersection (when viewed from above,
as seen in FIG. 2) of spiral 34 and radial reference line 23 to move
continuously radially outward from intersection at point 35 to
intersection at point 36. In this arrangement, each point of intersection
in the radial progression from point 35 to point 36 will correspond to a
different progressive angular orientation for one revolution of disc 24.
An index 38 established on one of discs 17, 24 will, thus, be
correspondingly moved progressively along a time scale 39 established on
the other of discs 17, 24.
A suitable arrangement provides a radially directed arrow-shaped projection
40 peripherally of disc 24 to constitute the index 38. Projection 40
includes a radial reference line 41 in radial alignment with spiral inner
point 35. Disc 24 is made with an outside diameter less than the outside
diameter of disc 17 to provide scale 39 circumferentially marginally about
disc 17 in an annular region of non-overlap of discs 17, 24. Scale 39
suitably includes three concentric time lines 43, 44, 45, each associated
with a different video recording speed. Each time line 43, 44, 45 includes
markings corresponding to respective increments of time (either time
recorded or unrecorded) associated with different radial positions of the
outer layer 33 of tape 12. To prevent the device 10 from sliding on the
surface of cassette 11 while measurements are being made, a triangular
enlargement 37 is provided in the plane of disc 17 to act as a platform
for holding apparatus 10 by the thumb.
The radius of the unused tape on the hub 14 of supply reel (or of used tape
on the take-up reel) changes in a definite, repeatable way as the length
of tape 12 is unwound from the reel at a particular given recording speed.
Each different radius represents a corresponding different amount of
recording time left (or recording time used). This known relationship is
mapped into the time lines 43, 44, 45 of scale 39, taking into account the
change in angular positioning of the pointer disc 24 that occurs for the
corresponding change in the intersection of spiral 34 and reference line
23 to match the position of the outside tape layer 33. Different tape
recording speeds are accommodated by providing different sets of numerical
character indicia on time lines 43, 44, 45. The described spiral
arrangement functions to couple position of the outside layer 33 along
reference line 23 with position of index 38 along time scale 39, so that a
small change in the radial direction along line 23 produces a large change
in the circumferential direction along scale 39. Such coupling enables the
size of the scale 39 carrying the time lines 43, 44, 45 to be large enough
to dimension and space the time increments in a visually, readily
discernable way. This offers a great advantage over conventional, directly
read rulers, which omit some readings and crowd other readings too closely
together. It will be appreciated that the period of spiral 34 can be
varied to change the relationship between the radial travel of the
intersection of spiral 34 with line 23 and the angular travel of disc 24.
For instance, spiral 34 could be configured to have two turns around
circle 30, rather than one, so that disc 24 will rotate twice, rather than
once, in moving the point of intersection from inner point 35 to outer
point 36. Index 38 will, thus, travel twice around scale 39, providing
even more spacing for listing time increments. Differentiation between
readings for the first and second revolutions could, for example, be made
using different colors.
In operation, the apparatus 10 is set down on top of a cassette 11 so that
the circle alignment guide 18 lines up over the tape reel hub 14 visible
through window 16. The thumb is placed down over enlargement 37 to
maintain alignment during measurement. Disc 24 is then rotated relative to
disc 17 about axis 28, until the intersection of spiral 34 on disc 24 with
radial reference line 23 on disc 17 matches the outside edge of the
outermost layer 33 of tape 12 wrapped around hub 14 viewable through
window 16. Rotation of disc 24, besides moving the point of intersection
radially of line 23, will simultaneously cause index 38 to move
circumferentially along scale 39 by a time differential corresponding to
the recording time represented by the amount of radial displacement of the
point of intersection along line 23. The content and spacing of time
representative indicia along time lines 43, 44, 45 are selected so that
the unused recording time represented by the amount of tape 12 left on hub
14 can be determined by reading the time indicated by the indicia of time
lines 43, 44 or 45 in alignment with the reference line indicator 41 of
the arrow-shaped projection 40. Which line 43, 44 or 45 is read depends on
which recording speed is being used, each line to be marked in accordance
with time increments corresponding to a respective different one of the
recording speeds.
Those skilled in the art to which the invention relates will appreciate
that, while the depicted implementation determines available recording
time from the decreasing radius of unrecorded tape wrapped around the hub
of the supply reel, the same principles can be applied to determine the
same information from the expanding radius of the take-up reel. Likewise,
the same can be used to determine the time already recorded, rather than
the time available. Likewise, it should be understood that there are yet
other substitutions and modifications, beyond those described above, that
can also be made to the described embodiment without departing from the
spirit and scope of the invention as described by the claims below. And,
it is intended that those claims cover all such equivalent arrangements.
* * * * *
|
|
|
|
|
|
|
Description |
|
