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Pickup device for high frequency signal record
3. Detailed Description of the Invention The present invention relates to an apparatus for
reproducing a record in which a very high frequency signal is written, such as a video signal, and
the pick-up needle has a constant needle pressure. It is an object of the present invention to keep
the contact state of the needle tip with the record constant and to prevent the occurrence of the
vertical tracking error. Fang 1 shows the main part of a conventional regenerating apparatus of
this type, and 2 is a cantilever having a pick-up needle 1 fixed at its free end, which is supported
by a pickup arm 4 via a rubber damper 3 . The pick-up needle 1 has a sled-like shape as shown in
FIG. IF2, which contacts the record surface 5 to pick up the signal recorded thereon, but this
record is rotated at high speed, in which case the record is recorded Due to surface nonuniformity, etc., runout occurs. As a result, the pick-up needle 1 is driven up and down, and its
needle pressure changes. Since the contact area of pick-up needle 1 to the record is about 3 ×
10 −7 d and the elastic limit of the record is about 1 × 10′VcI &, the needle pressure of the
limit added to the record is about 11 when using pressure gradient . In actual use, it is selected to
be about 0, 2ψ. By the way, assuming that the displacement of the record surface is up to 200μ
due to the upset of the record, the force required to lift the pick-up needle 1 by one pinch is 7g(even compared to the normal EndPage: 1-audio If it is a small value), 1.4? An increase in needle
pressure occurs, and a pressure exceeding the elastic limit is applied to the record, which
permanently deforms the record. In addition, when the cantilever 2 pivots up and down, the pickup needle 1 moves after chewing as shown by t in FIG. That is, vertical tracking errors occur.
Assuming that the length of the cantilever 2 is 20 battles, the mounting angle θ = 30 °, the
amount of surface deviation h = 200 μ, and the rotational speed of the record is 1800 r, p, m, a
screen bend of about 4 μsec at a diameter of 200 m It will occur. Furthermore, due to the tilting
of the cantilever 2, the contact state of the pick-up needle 1 with the record surface 5 changes
from the state shown in FIG. 2 (5) to the state shown in CB) or (0), A) It will not be enough to
keep it. The present invention is intended to eliminate the three drawbacks as described above,
and the third figure shows an example of the invention shown in JP-A-49-105503 (2), and 2 has
the pick-up needle 1 The support member 7 is supported by the support piece 7 via the rubber
damper 3.
The support piece 7 is fixed to the membrane 8 of rubber M, which is stretched over the opening
of the holding ring 1 o fixed to the lower surface of the pickup-arm 4 and closes the opening.
Then, oil 9 is filled in a space enclosed in a sealed state by the lower surface of the pickup arm 4
and the holding ring 10 and the membrane 8 to constitute an damper. A contact bar 6 made of a
material having a small friction resistance, such as Teflon, is fixed to the support piece 7 and is in
contact with the lever surface 5. When the recording surface 5 moves up and down due to the
surface deviation, the contact rod 6 moves up and down along with it, and moves the support
piece 7 up and down. As a result, the cantilever 2 attached to the support piece 7 is also moved
up and down in parallel. Eventually, the cantilever 2 and the pick-up needle 1 move up and down
with the record surface 5 but do not move relative to the record surface 5. Therefore, the
pressure force or needle pressure on the recording surface 5 of the pick-up needle 1 is kept
constant. The needle pressure can be adjusted by adjusting the length of the contact bar 6.
Further, since the tilt of the cantilever 2 does not change, vertical tracking errors do not occur,
and the contact state of the pick-up needle 1 does not change. Fang 4 (4) and (B) are a side view
and a bottom view showing an embodiment of the fan 2. In this example, the pick-up needle 1 is
fixed to the lower surface of the support piece 11. Two further contact pieces 12 are fixed on the
lower surface of the support piece 11, and they are arranged to form an isosceles triangle with
the pick-up needle 1 at the top. One end of a cantilever 15 is attached to the upper surface of the
support piece 11 via a rubber damper 13, and the other end is attached to the pickup arm 4 via a
rubber damper 14. The attachment position of the cantilever 1 # 5 to the support piece 11 is
selected to be close to the contact piece 12. When the recording surface 5 moves up and down,
its displacement is transmitted to the support piece 11 through the pick-up needle 1 and the two
contact pieces 34, so the support piece 11 moves up and down in parallel. Therefore, even if the
tilt of the cantilever 15 changes, the contact state of the pick-up needle 1 with respect to the
record surface 5 does not change, and vertical tracking error does not occur, and the changed
contact pressure 1 disperses to three points. Since the mounting position of 15 is selected to be
close to the contact piece 12, the change in the contact pressure shared by the pick up needle 1,
that is, the needle pressure is small. As described above, according to the present invention, the
pick-up needle is supported by the translatable support piece, and the support piece is provided
with the contact member, which is brought into contact with the record surface to move the
record surface up and down. Since it is made to translate it up and down in parallel through the
support piece, even if the record surface is displaced up and down, the contact pressure changes
as the pressure on the contact member changes. Stop and keep the needle pressure constant.
In addition, support pick-up needle EndPage: 26, other than the above agent EndPage: 3
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