Title of Invention

VIDEO CASSETTE RECORDER

Abstract A video cassette recorder comprises a pair of pole base assemblies each of which includes a guide roller for guiding a running magnetic tape to help maintain a proper contact with a head drum having at least one video head, a base and a post for supporting the guide roller, and a lever for selectively vertically moving the posts depending on operation modes. The post is mounted to the base and movable vertically, and the guide roller is rotatably fixed to top of the post. The lever is provided with a pair of stepped portions, is mounted under a deck, and horizontally moves depending on the operation modes so that the stepped portions selectively contact and move the posts by a desired height to tilt the tape between the guide rollers at an angle, thereby allowing the video head of the head drum to correctly read tracks recorded on the magnetic tape.
Full Text Field of the Invention
The present invention relates to a video cassette
recorder ("VCR"); and, more particularly, to a VCR capable of
allowing a video head to correctly read video tracks recorded
on a magnetic tape during a special reproduction mode wherein
the tape travels at a different speed from a standard speed.
Description of the Prior Art
There is shown in Fig. 1 a schematic top view of a deck
10 of a conventional VCR. In the VCR, a magnetic tape T in a
tape cassette CS is drawn toward a head drum 4 and disposed
around a periphery thereof by a pair of pole base assemblies
1 moving along a pair of slots (not shown) on the deck 10.
Each of the pole base assemblies 1 is provided with a guide
roller 2 for guiding the running tape T and helping it to
maintain a proper contact with the head drum 4. The tape T
runs longitudinally between a supply reel 11 and a take-up
reel 12, passing through an audio/control head assembly 5.
Since the head drum 4 is inclined with respect to the
longitudinal direction of the tape T, a pair of video heads of
the drum 4 rotates at a constant speed and alternately
transcribes paths, or tracks, along the tape T that are

disposed at an angle relative to the longitudinal direction of
the tape T. Therefore, during a recording mode wherein the
tape T is transported at a predetermined standard speed,
successive adjacent video tracks Ta, an audio track Tb and a
control tracks Tc are formed on the tape, as shown in Fig. 2.
Furthermore, during a normal reproduction mode, the tape T is
transported at the standard speed, the rotating heads
successively read the video tracks Ta in the order in which
they were recorded, and an audio head and a control head of
the audio/control head assembly 5 read the audio and the
control tracks Tb, Tc, rspectively. However, during a fast
forward reproduction mode wherein the tape T is transported at
a speed faster than the standard speed, the rotating video
heads alternately scan the video tracks Ta, forming an angle
a with respect to a video track Ta to be read, as shown in
Fig. 3; during a fast reverse reproduction mode wherein the
tape is transported in a reverse direction at a speed faster
than the standard speed, the video heads alternately scan the
tracks, forming an angle /3 with respect to a video track Ta to
be read, as shown in Fig. 4; and during a still or slow
reproduction mode wherein the tape is still or travels at a
speed slower than the standard speed, the rotating heads
alternately scan the video tracks, forming an angle y with
respect to a video track to be read, as shown in Fig. 5.
Therefore, during the special reproduction modes in the
conventional VCR, as a result of the tape travelling at a
different speed from the standard speed while the video heads
rotate at the constant speed, there are produced noises on a
screen.
Summary of the Invention
It is, therefore, a primary object of the invention to
provide a VCR capable of allowing a video head of a head drum
to correctly read the tracks recorded on a magnetic tape
during a special reproduction mode wherein the tape travels at
a different speed from a standard speed, thereby reducing the
noises on the screen.
In accordance with one aspect of the present invention,
there is provided a video cassette recorder comprising: a pair
of pole base assemblies each of which includes a guide roller
for guiding a running magnetic tape to help maintain a proper
contact with a head drum having at least one video head, a
base and a post for supporting the guide roller, wherein the
post is mounted to the base and movable vertically and the
guide roller is rotatably fised to top of the post; and means
for selectively vertically moving the posts and the guide
rollers depending on operation modes, thereby allowing the
video head of the head drum to correctly read video tracks
recorded on the magnetic tape.
Brief Description of the Drawings
The above and other objects and features of the present
invention will become apparent from the following description
of preferred embodiments taken in conjunction with the
accompanying drawings, in which:
Fig. 1 shows a schematic top view of a deck of a
conventional VCR;
Fig. 2 illustrates a view of a magnetic tape on which
video tracks, an audio track and a control track are recorded;
Figs. 3 to 5 set forth views of the magnetic tape,
showing various paths of a head scanning the tracks recorded
on the magnetic tape during a fast forward, a fast reverse,
and a still or slow reproduction modes, respectively, in the
conventional VCR;
Fig. 6 shows a schematic top view of a deck of a VCR of
the present invention;
Fig. 7 represents a cross-sectional view of an inventive
pole base assembly of the VCR of the present invention;
Fig. 8 represents a partial sectional view of the VCR in
Fig. 6, showing the pole base assemblies and the lever;
Fig. 9 represents a schematic view of the VCR in Fig. 6,
showing an interaction of the pole base assemblies and the
lever during a fast forward reproduction mode;
Fig. 10 represents a schematic view of the VCR in Fig. 6,
showing another interaction of the pole base assemblies and
the lever during a fast reverse reproduction mode; and
Fig. 11 represents a schematic view of the VCR in Fig. 6,
showing another interaction of the pole base assemblies and
the lever during a still or slow reproduction mode.
Detailed Description of the Preferred Embodiment
Referring to Figs. 6 to 8, a VCR in accordance with a
preferred embodiment of the present invention comprises a pair
of pole base assemblies 30, each of which includes a guide
roller 40 for guiding a running magnetic tape T to help
maintain a proper contact with a head drum 4 having a pair of
video heads, a base 31 and a post 60 for supporting the guide
roller 40; a lever 80 for selectively vertically moving the
post 60 and hence the guide roller 40 depending on operation
modes thereof; and an audio/control head assembly 50 having a
main and a sub control heads 54, 53.
The post 60 is provided with an upper flange 61, a lower
flange 63, a central hole 64 longitudinally passing
therethrough and a tapped portion 65 formed at top thereof.
The post 60 is mounted to the base 31 and movable vertically
relative thereto. The upper and the lower flanges 61, 6 3 are
disposed above and below the base 31, restricting the downward
and upward movement of the post 60, respectively. The guide
roller 40 is rotatably mounted to a shaft 41 having a screw
member 42 fitted in the tapped portion 65 of the post 60. An
elastic member 70 is interposed between the base 31 and the
lower flange 63, biasing the post 60 downwardly and allowing
the guide roller 40 to resiliently guide the running tape T.
The lever 80 is provided with first and second stepped
portions 81, 82, a plurality of elongated guide holes 83 and
a boss 84 disposed at one end thereof. The lever 80 is
disposed under the deck 10 and held by a plurality of guide
holders 13 which downwardly protrudes from a bottom surface of
the deck 10 and fit through the elongated guide holes 83,
respectively. The boss 84 is inserted in a trace groove 21
formed on a bottom surface of a cam 20 rotated by a driving
motor 100, moving along the trace groove 21 while the cam 20
rotates depending on the operation modes so that the lever 80
is horizontally displaced and the stepped portions 81, 82
selectively vertically move the posts 60 and hence the guide
roller 40 depending on the operation modes.
The audio/control head assembly 50 is disposed between
the head drum 4 and a take-up reel 12, recording an audio and
a control tracks on the magnetic tape T or reading the audio
and the control tracks recorded thereon.
Operation of the VCR of the present invention will now be
described with reference to Figs. 3 to 11.
First, upon a loading of a tape cassette, the pole base
assemblies 30 move along a pair of guide slots (not shown) on
the deck 10, drawing the magnetic tape T in a tape cassette CS
loaded in the VCR and bringing it into a contact with the head
drum 4. At this time, the posts 60 becomes disposed above the
lever 80, as shown in Fig. 8 and the VCR performs a normal
reproduction mode wherein the tape runs at a standard speed
under the above condition.
Then, upon a fast forward reproduction mode wherein the
magnetic tape T travels in a forward direction at a speed
faster than the standard speed, the lever is moved to the
right in Fig. 8 so that, as shown in Fig. 9, the first stepped
portion 81 thereof contacts and upwardly moves the right post
60 and hence the right guide roller 40 by a certain height to
tilt the tape between the guide rollers 40 at an angle a (see
Fig. 3), thereby allowing the video heads of the head drum 4
to correctly read the video tracks on the tape T during the
fast forward reproduction mode.
Upon a fast reverse reproduction mode wherein the
magnetic tape travels in a reverse direction at a speed faster
than the standard speed, the lever is moved to the left in
Fig. 8 so that, as shown in Fig. 10, the second stepped
portion thereof contacts and upwardly moves the left post 60
and hence the guide roller 40 by a certain height to tilt the
tape between the guide rollers 40 by an angle j3 (see Fig. 4),
thereby allowing the video heads to correctly follow the video
tracks on the tape T during the fast reverse reproduction
mode.
Furthermore, upon a still or slow reproduction mode
wherein the magnetic tape is still or travels at a speed
slower that the standard speed, the lever is moved to the left
in Fig. 8 so that, as shown in Fig. 11, the second stepped
portion thereof contacts and upwardly moves the left post 60
and hence the left guide rollers 40 to tilt the tape between
the posts 60 by an angle y (see Fig. 5), thereby allowing the
video heads to correctly follow the video tracks on the tape
T during the still or slow reproduction mode.
On the other hand, as a result of the rising of the tape
passing through the audio/control head assembly 50 during the
fast forward reproduction mode, the main control head 54 of
the audio/control head assembly 50 may not read the control
track recorded on the tape faithfully. However, the sub
control head 54 disposed above the main control head 54 is
activated and the main and the sub control heads 54, 53
cooperate to read the control track recorded on the tape T
during the fast forward reproduction mode, thereby making it
possible to faithfully read the control track even when the
height of the running tape is raised. Since the sub control
head 53 is deactivated during the other operation modes, it
does not influence the video tracks on the tape.
As described above, according to the VCR of the present
invention, even during a special reproduction mode wherein the
tape travels at a different speed from the standard speed, the
video heads can correctly read the video tracks recorded on
the tape, thereby reducing noises on a screen.
Although the invention has been shown and described with
respect to the preferred embodiments, it will be understood by
those skilled in the art that various changes and
modifications may be made without departing from the spirit
and scope of the invention as defined in the following claims.
WE CLAIM :
1. A video cassette recorder comprising:
a pair of pole base assemblies each of which includes a
guide roller for guiding a running magnetic tape to help
maintain a proper contact with a head drum having at least one
video head, a base and a post for supporting the guide roller,
wherein the post is mounted to the base and movable vertically
and the guide roller is rotatably fised to top of the post;
and
means for selectively vertically moving the posts and the
guide rollers depending on operation modes, thereby allowing
the video head of the head drum to correctly read video tracks
recorded on the magnetic tape.
2. The recorder of claim 1, wherein said post moving means
includes a lever provided with a pair of stepped portions, the
lever being mounted under a deck and horizontally moving
depending on the operation modes so that the stepped portions
selectively contact and move the posts to tilt the tape
between the guide rollers at an angle.
3. The recorder of claim 2, wherein the lever is further
provided with a plurality of elongated guide holes and a boss
disposed at one end, the lever being held by a plurality of
guide holders which downwardly protrudes from a bottom surface
of the deck and fit through the elongated guide holes,
respectively, the boss being inserted in a trace groove formed
on a cam and moving along the trace groove of the cam while
the cam rotates depending on the operation modes so that the
lever is horizontally moved.
4. The recorder of claim 1, wherein the post is provided
with an upper flange and a lower flange which are disposed
above and below the base, restricting the downward and upward
movement of the post, respectively.
5. The recorder of claim 4, wherein an elastic member is
interposed between the base and the lower flange, biasing the
post downwardly.
6. The recorder of claim 4, wherein the post is further
provided with a tapped portion formed at top thereof, and the
guide roller is rotatably mounted to a shaft having a screw
member fitted in the tapped portion.
7. The recorder of claim 1, further comprising an
audio/control head assembly provided with a main control head
and a sub control head disposed above the main control head,
the main and the sub control heads being activated and
cooperating to faithfully read a control track recorded on the
tape during a fast forward reproduction mode.
Dated this 24th day of December, 1996


A video cassette recorder comprises a pair of pole base
assemblies each of which includes a guide roller for guiding
a running magnetic tape to help maintain a proper contact with
a head drum having at least one video head, a base and a post
for supporting the guide roller, and a lever for selectively
vertically moving the posts depending on operation modes. The
post is mounted to the base and movable vertically, and the
guide roller is rotatably fixed to top of the post. The lever
is provided with a pair of stepped portions, is mounted under
a deck, and horizontally moves depending on the operation
modes so that the stepped portions selectively contact and
move the posts by a desired height to tilt the tape between
the guide rollers at an angle, thereby allowing the video head
of the head drum to correctly read tracks recorded on the
magnetic tape.

Documents:

2233-cal-1996-abstract.pdf

2233-cal-1996-assignment.pdf

2233-cal-1996-assignment1.1.pdf

2233-cal-1996-claims.pdf

2233-cal-1996-correspondence.pdf

2233-cal-1996-correspondence1.1.pdf

2233-cal-1996-description (complete).pdf

2233-cal-1996-drawings.pdf

2233-cal-1996-form 1.pdf

2233-cal-1996-form 2.pdf

2233-cal-1996-form 3.1.pdf

2233-cal-1996-form 3.pdf

2233-cal-1996-form 5.1.pdf

2233-cal-1996-form 5.pdf

2233-cal-1996-form 6.1.pdf

2233-cal-1996-form 6.pdf

2233-cal-1996-gpa.pdf

2233-cal-1996-gpa1.1.pdf

2233-cal-1996-granted-abstract.pdf

2233-cal-1996-granted-claims.pdf

2233-cal-1996-granted-description (complete).pdf

2233-cal-1996-granted-drawings.pdf

2233-cal-1996-granted-form 1.pdf

2233-cal-1996-granted-form 2.1.pdf

2233-cal-1996-granted-form 2.pdf

2233-cal-1996-granted-specification.pdf

2233-cal-1996-others.pdf

2233-cal-1996-pa.pdf

2233-cal-1996-priority document.pdf

2233-cal-1996-priority document1.1.pdf

2233-cal-1996-reply to examination report.pdf

2233-cal-1996-reply to examination report1.1.pdf

2233-cal-1996-specification.pdf

2233-cal-1996-translated copy of priority document.pdf

2233-cal-1996-translated copy of priority document1.1.pdf


Patent Number 244069
Indian Patent Application Number 2233/CAL/1996
PG Journal Number 47/2010
Publication Date 19-Nov-2010
Grant Date 16-Nov-2010
Date of Filing 24-Dec-1996
Name of Patentee DAEWOO ELECTRONICS CO. LTD.
Applicant Address 541, 5-GA, NAMDAEMOON-RO, JUNG-KU, SEOUL
Inventors:
# Inventor's Name Inventor's Address
1 GWANG JUN VIDEO RESEARCH CENTER, DAEWOO ELECTRONICS CO., LTD. 541, 5-GA, NAMDAEMOON-RO, JUNG-KU, SEOUL
PCT International Classification Number N/A
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 95-56876 1995-12-26 Republic of Korea
2 95-56868 1995-12-26 Republic of Korea
3 95-56877 1995-12-26 Republic of Korea