Optical disk player

In an optical disk player according to this invention, a movable chassis mounted with an optical pickup, a turntable and the like is supported by springs joined with respective positions of a frame, and in this optical disk player, dampers are inserted between the frame and the movable chassis to absorb the energy of vibrations of the movable chassis. At the same time, a correcting means such as a coiled spring is so arranged as to be capable of changing the biasing force for biasing the movable chassis in a neutral condition with respect to the frame by adjustment operation. With the above arrangement, the slope of Q-value of the resonance region becomes moderate enough at the leading edge of the slope, and thus the vibration isolation characteristic is improved, so that sound omissions tend not to occur. The degradation of the vibration isolation characteristic of the damper that usually occurs on tilt of the chassis is effectively prevented. At the same time, a collision between the frame and the movable chassis can be prevented without increasing the movable range of the movable chassis with respect to the frame.

TECHNICAL FIELD 
The present invention relates to an optical disk player having an improved 
vibration isolation characteristic and suitable for use in a moving 
object, such as an automobile, an aircraft or the like. 
BACKGROUND ART 
In the conventional cassette tape player for cars using magnetic tapes, no 
vibration isolation mechanism has been substantially provided although the 
performance of the player falls due to wow and flutter caused by the 
vibration of the car, because the degradation of the performance is not 
reagarded as very serious problem. 
However, when an optical disk player for scanning and reproducing 
high-density signals recorded on a disk by the use of an optical pickup is 
mounted in the moving object, such as the automobile, the aircraft or the 
like, sound omissions tend to occur due to vibrations of the moving 
object. Therefore, the principal part of the player is placed on a player 
frame through rubber cushions so as to be insulated from the vibration. 
But quality factor Q of the resonance region of the vibration generated in 
the principal part of the player tends to be inevitably large, so that it 
is often difficult to have the player operated normally. In addition, the 
frequency band of the vibrations caused under various severe conditions 
with which the car is met, normally includes the above resonance region. 
Therefore, if the optical disk player for cars is isolated from the 
vibrations only by rubber cushions, sound omissions occur, and it becomes 
difficult to enable the optical disk player to be normally operated. 
Hence, the following mechanism is proposed as the vibration isolation 
mechanism of the optical disk player for cars instead of rubber cushions. 
In the mechanism, a movable chassis (on which an optical pick-up, a 
turntable and the like are mounted) is suspended by suspension coiled 
springs in several positions of a frame such as a stationary chassis or a 
cabinet, and dampers which prevent the movable chassis from vibrating are 
inserted between the frame and the movable chassis so that the movable 
chassis can be floated with respect to the frame. Thus, resonance 
frequency f.sub.O in the lateral (horizontal) direction of the vibration 
system is decreased. Hence, by adoption of the above vibration isolation 
mechanisum, the slope of Q-value of the resonance region becomes moderate 
enough at the leading edge of the slope in comparison with the case in 
which the rubber cushion is adopted, so that the noted sound omission does 
not occur, and the vibration isolation characteristic is greatly improved. 
However, if the optical disk player having the vibration isolation 
mechanism as described above is mounted on the car, the following further 
trouble arises. 
When the frame is mounted in the player mounting position of the car at a 
given angle with the horizontal plane of the car, the direction of the 
gravity acting on the movable chassis changes, so that the movable chassis 
tends to be displaced from a neutral equilibrium position with respect to 
the frame. 
The movable chassis is displaced from the neutral equilibrium position with 
respect to the frame until the dampers are elastically deformed to 
re-establish an equilibrium state. Thereby, the vibration isolation 
characteristic of the damper is degraded. In addition, as the movable 
chassis deviates from the neutral equilibrium position with respect to the 
frame, the distance between the movable chassis and the frame in the 
displacement direction of the movable chassis is decreased, so that the 
movable range in the displacement direction of the movable chassis is 
decreased with respect to the frame. 
DISCLOSURE OF INVENTION 
In order to solve the above problems, there is disclosed an optical disk 
player of the present invention, in which a movable chassis is mounted 
with an optical pickup, a turntable and the like, and so supported by 
coiled springs joined with a frame in several positions as to be floated 
with, respect to the player. The optical disk player frame further 
comprises dampers inserted between the frame and the movable chassis to 
absorb the energy of vibrations of the movable chassis, and biasing means 
for correction capable of varying a biasing force to enable the movable 
chassis to be biased with respect to the frame by adjustment operation, 
and also inserted between the frame and the movable chassis, whereby the 
positional deviation of the movable chassis due to the setting angle of 
the frame from a neutral equilibrium position with respect to the frame is 
corrected by changing the biasing force by adjustment operation, and the 
movable chassis is kept in the neutral equilibrium position regardless of 
the setting angle. 
With the above arrangement, the increase in Q-value of the resonance region 
can be prevented, so that the vibration isolation characteristics are 
improved and sound omissions tend not to occur. The degradation of the 
vibration isolation characteristic of the damper can be effectively 
prevented, and at the same time, a collision between the frame and the 
movable chassis can be prevented without increasing the movable range of 
the movable chassis with respect to the frame.

BEST MODE OF CARRYING OUT THE INVENTION 
An embodiment in which the present invention is applied to an optical disk 
player for cars will be described with reference to the accompanying 
drawings. FIGS. 1 to 11 show the embodiment and firstly, a state of a 
principal part 2 of the player mounted on a frame 1, that is, a stationary 
chassis will be described with reference to FIGS. 1 to 3. 
The principal part 2 of the player comprises a movable chassis 2a, an 
optical pickup 6 which is movable along a guide groove (not shown) formed 
in the movable chassis 2a, and a turntable 3a on which an optical disk 
(not shown) as a recording medium is to be placed. On the movable chassis 
2a, there are also mounted a motor 3 and the like. The disk (not shown) is 
turned by the turntable 3a driven by the motor 3. The disk inserted in the 
direction of arrow A in FIG. 1 is chucked by a disk chuck 4 rotatably 
mounted on the free end of a chucking arm 5 which is vertically swingable. 
The frame 1 accommodated in a cabinet 30 (see FIG. 4) and mounted in a 
player mounting position (not shown) of the car comprises a pair of side 
plates 7 and a connecting member 8 which connects the side plates 7 with 
each other. The movable chassis 2a is suspended from the frame 1 through 
four suspension coiled springs 10. Four dampers 11 are inserted between 
the movable chassis 2a and the side plates 7 of the frame 1 near the 
respective suspension coiled springs 10 so as to absorb the energy of 
vibrations of the principal part 2 of the player. Therefore, the principal 
part 2 of the player is kept in a floating state with respect to the frame 
1. 
A mounting state correction mechanism 12 is disposed between the connecting 
member 8 of the frame 1 and an upper plate 9 of the movable chassis 2a so 
as to change an equilibrium position of the principal part 2 of the player 
with respect to the frame 1 when the frame 1 is so secured as to have a 
given angle with the horizontal plane H of the car (see FIGS. 10 and 11). 
The mounting state correction mechanism 12 will be described later with 
reference to FIGS. 7 and 8. 
Accommodated in the cabinet 30 shown in FIG. 4 is the frame 1 to which the 
principal part 2 of the player and the like are secured as shown in FIG. 
1. When a lid 31 is swung on a screw 32, with which the lid 31 is attached 
to the upper wall of the cabinet 30, an adjustment-operation opening 33 
formed in the upper wall of the cabinet 30 is opened or closed, so that an 
eccentric cam 18 of the mcunting state correction mechanism 12 can be 
turned with a screw-driver (not shown) inserted through the opening 33. 
The constitution and function of the damper 11 will be described with 
reference to FIGS. 5 to 6D. 
The damper 11 comprises a vessel 11a mounted on the side plate 7 of the 
frame 1, and a rod 11b fixedly fitted in a mounting hole 45 of the movable 
chassis 2a. 
The vessel 11a is made of an elastic material such as rubber and defines a 
space 40 in which a viscous fluid is sealed. A movable member 41 is so 
disposed as to project into the substantially central portion of the space 
40. The movable member 41 is of a quadrangular prism, on the outer 
periphery of which projections 42 are disposed so as to increase viscous 
drag of the movable member 41 in the viscous fluid, and into a hole 43 
forming the inner periphery of which the rod 11b is press-fitted. The 
space 40 is defined by four walls which are in opposed relation to the 
outer periphery of the movable member 41, so that the space 40 has a 
substantially square cross-secton. The rod 11b may comprise a rod body 
with a cylindrical body of rubber mounted on the rod body. 
The vessel 11a has a lid 48 at the outer side thereof and a stopper 44 of a 
thick ring-like flange at the inner side thereof. Between the movable 
member 41 and the stopper 44, there is disposed a film-like connecting 
member 49 which protrudes more than the stopper 44 like a donut. Between 
the stopper 44 and the connecting member 49, there is an anuular groove 50 
of a substantially triangular shape in section, the width of which 
gradually decreases towards its bottom. A groove 46 is formed in the outer 
periphery of the stopper 44 and is engaged with the rim of a hole 28 
formed in the side plate 7 of the frame 1. A pair of projections 47 formed 
in the groove 46 are engaged with recesses (not shown) formed in the rim 
of the hole 28 in order to determine the setting angle of the vessel 11a 
in the side plate 7. 
In this embodiment, silicone oil (12,000 cS) fills the space 40 formed in 
the body of the vessel 11a made of butyl rubber, and then the lid 48 of 
butyl rubber is attached to the vessel body so as to enclose the oil. The 
vessel 11a is mounted in the side plate 7 of the frame 1 in such a way 
that the pair of projections 47 of the vessel 11a are aligned with each 
other along the horizontal line. 
If the frame 1 is vertically moved, for example, moved downward with 
respect to the movable chassis 2a, the vessel 11a is also moved downward, 
that is, in a direction perpendicular to the axial direction thereof as 
shown in FIG. 6C, and the rod 11b fixedly fitted in the mounting hole 45 
of the movable chassis 2a is also to be moved downward together with the 
vessel 11a, but due to elastic deformation of the connecting member 49 
made of the film, the rod 11b with the movable member 41 is relatively 
moved in the space 40 in three dimensional direction. In other words, the 
rod 11b is not substantially moved and as shown in FIG. 6C, the vessel 11a 
is so deformed as to move downward only the outer portion of the vessel 
11a, such as the stopper 44 and the like. Therefore, the viscous drag is 
generated between the silicone oil and the movable member 41 since the 
silicone oil in the vessel 11a is moved from the lower position to the 
upper position of the movable member 41, so that the movable chassis 2a is 
prevented from assuming the vibration of the frame 1, because the energy 
of the vibration is absorbed by the viscous drag. 
When the frame 1 vibrates in the back-and-forth direction (in the 
right-and-left direction in FIG. 3) with respect to the movable chassis 
2a, the vessel 11a is deformed in a similar way as indicated in FIG. 6C. 
The Vibration from the frame 1 to the movable chassis 2a is sufficiently 
attenuated as the vertical vibration is. 
If the frame 1 vibrates in the right-and-left direction in FIG. 2 with 
respect to the movable chassis 2a, the vessel 11a is so moved as to 
approach the movable chassis 2a as indicated in FIG. 6D, so that the 
vibration from the frame 1 to the movable chassis 2a is sufficiently 
attenuated due to the deformation of the vessel 11a shown in FIG. 6D, and 
the same may be said of the vessel 11a moved away from the movable chassis 
2a. 
The stopper 44 and lid 48 of the vessel 11a function as stoppers and impact 
absorbers when the vessel 11a is overrun in the axial direction of the 
damper 11 due to the vibration of the frame 1. That is, when the stopper 
44 of the vessel 11a comes closer to the movable chassis 2a from the state 
shown in FIG. 6D, the movable chassis 2a is elastically brought into 
contact with the side surface of the stopper 44. At the same time, the 
flat distal end of the movable member 41 is elastically brought into 
contact with the inner side of the lid 48. Therefore, the impact energy 
can be absorbed and further movement of the frame 7 toward the movable 
chassis 2a can be prevented. 
The projections 42 of the movable member 41 function as stoppers and impact 
absorbers when the frame 1 vibrates in the vertical or back-and-forth 
direction thereof with respect to the movable chassis 2a. That is, as 
indicated in chain-dotted lines in FIG. 6B, when the movable member 41 
vibrates and relatively comes close to the upper wall of the space 40, the 
upper projection 42 is elastically brought into contact with the upper 
wall. As a result, the impact energy can be absorbed, and further 
displacement of the rod 11b relative to the vessel 11a can be prevented. 
Differing from the conventional damper whose vessel has two spaces, the 
vessel 11a of the damper 11 comprises only one space 40 as mentioned 
above, and the vibration energy is dissipated due to the movement of the 
movable member 41 against the viscous fluid in the space 40. As the 
projection 42 protrudes from each of the four outer surfaces of the 
movable member 41 of the quadrangular prism, the surface of the movable 
member 41 is uneven, so that the energy dissipation due to the movement of 
the movable member 41 becomes larger, because the surface area of the 
movable member 41 immersed in the viscous fluid is effectively increased. 
Furthermore, since the vessel 11a is made of the butyl rubber, the vessel 
11a deforms repeatedly as the frame 1 vibrates with respect to the movable 
chassis 2a, so that the vibration energy is dissipated in the butyl 
rubber. Therefore, the vessel 11a, in other words, the damper 11, has a 
large energy absorbing capacity although it is rather small. 
As shown in FIGS. 7 to 9, the mounting state correction mechanism 12 
comprises a rectangular frame 13, two pairs of guide hooks 14 formed on 
the connecting member 8 of the frame 1 in order to have the rectangular 
frame 13 slid along the guide hooks 14, an eccentric cam 18 for causing 
the rectangular frame 13 to be slid along the guide hooks 14, and a coiled 
spring 17 which joins engaging holes 16 and 15, respectively formed in the 
rectangular frame 13 and the upper plate 9 of the movable chassis 2a. The 
coiled spring 17 can give a biasing force a predetermined magnitude to the 
movable chassis 2a so as to correct a positional deviation of the movable 
chassis 2a from the neutral equilibrium position with respect to the frame 
1 when the frame 1 is mounted at a given angle with the horizontal plane. 
However, the coiled spring 17 has such a low spring constant as it 
scarcely gives any influence to the vibration system which comprises the 
frame 1, the principal part 2 of the player, the suspension coiled springs 
10 and the dampers 11, (whose frequency f.sub.0 in the lateral 
(horizontal) direction is generally low). 
The mounting state correction mechanism 12 is so arranged between the frame 
1 and the movable chassis 2a as to have its central line, by which the 
mechanism 12 is symmetrically bisected in right and left portions, 
substantially included in the perpendicular plane including the center of 
gravity G of the principal part 2 of the player. The direction of the 
biasing force of the coiled spring 17 acting on the movable chassis 2a is 
always within the perpendicular plane, and the positional deviation of the 
movable chassis 2a from the neutral equilibrium position with respect to 
the frame 1 is substantially kept in parallel with the perpendicular 
plane. In this embodiment, the coiled spring 17 is arranged at an angle of 
about 10.degree. with the bottom surface of the movable chassis 2a, which 
is the reference surface of the principal part 2 of the player, when the 
principal part 2 of the player is held in the neutral equilibrium 
position. 
Formed in the head of the eccentric cam 18 is a notch which is to be 
engaged with the screwdriver. A screw hole 20 is formed in the bottom of 
the eccentric cam 18. A locking projection 21 is formed near the outer 
edge of the bottom surface. As is apparent from FIG. 9, the eccentric cam 
18 is secured with a screw 24, on which a washer 23 and a biasing spring 
22 are mounted. Thus, the eccentric cam 18 is pressed against the 
connecting member 8 with the biasing spring 22, so that the locking 
projection 21 of the eccentric cam 18 is selectively engaged with one of a 
plurality of radial grooves formed around a hole 25 formed in the frame 1. 
Therefore, the eccentric cam 18 is held at a desired adjusted angular 
position. 
The function of the mounting state correction mechanism 12 at the time when 
the frame 1 is mounted in the player mounting position of the car in 
parallel with, or at a given angle with the horizontal plane H of the car, 
will be described with reference to FIGS. 3, 10, and 11. 
When the frame 1 is mounted in the player mounting position of the car in 
parallel with the horizontal plane H of the car, the principal part 2 of 
the player is held by the suspension coiled springs 10 and the correcting 
coiled spring 17 and the dampers 11 is in the neutral equilibrium position 
as shown in FIG. 3. Therefore, no force is transmitted from the movable 
chassis 2a to the dampers 11. 
If the frame 1 is mounted in the player mounting position at a given angle 
with the horizontal plane H of the car with adjusting the coiled spring 17 
of the mounting state correction mechanism 12, the direction of gravity of 
the principal part 2 of the player acting on the bottom surface of the 
movable chassis 2a changes, so that the force from the movable chassis 2a 
is transmitted to the dampers 11 and then, the dampers 11 deform as shown 
in FIG. 10. Thus, the movable chassis 2a deviates from the neutral 
equilibrium position with respect to the frame 1. 
Therefore, if the eccentric cam 18 is turned with the screwdriver (not 
shown) inserted through the adjustment operation opening 33 so as to 
operate the mounting state correction mechanism 12 shown in FIG. 7, the 
eccentric cam 18 and the rectangular frame 13 are moved from the position 
inicated in the solid lines to the position indicated in chain-dotted 
lines in FIG. 7, and thereby, the biasing force of the coiled spring 17 
increases and the movable chassis 2a is moved from the position indicated 
in solid lines to the position indicated in chain-dotted lines in FIG. 7. 
Therefore, by means of properly adjusting the angular displacement of the 
eccentric cam 18 of the mounting state corection mechanism 12, it is easy 
to return the movable chassis 2a from the position shown in FIG. 10 to the 
neutral equilibrium position shown in FIG. 11. 
FIGS. 12 and 13 show another embodiment of the mounting state correction 
mechanism 12 shown in FIG. 1. In this embodiment, one end of the coiled 
spring 17 is hooked in one of a plurality of engaging holes 34 formed in a 
line in the connecting member 8 of the frame 1. By selectively hooking one 
end of the coiled spring 17 in one of the engaging holes 34, the biasing 
force of the coiled spring 17 can be changed like the mechanism 
illustrated in FIGS. 7 and 8. 
If the arrangements shown in FIGS. 12 and 7 are compared, it is apparent 
that the mounting state correction mechanism 12 shown in FIGS. 12 and 13 
is not only simpler in construction than the one shown in FIGS. 1 to 11, 
but also has the coiled spring 17 the capable of being changed larger than 
that of the mechanism 12 shown in FIGS. 1 to 11. Therefore, the mounting 
state correction mechanism 12 shown in FIGS. 12 and 13 is more suitable 
for the optical disk player for cars which is mounted in the player 
mounting position sometimes in parallel with and sometimes at a given 
angle with the horizontal plane of the car. 
The present invention is exemplified by the above embodiments. However, 
various changes and modifications may be made without departing from the 
spirit and scope of the invention. For example, in the embodiment shown in 
FIGS. 12 and 13, the end of the coiled spring 17 may be engaged with the 
intermediate one of three or more engaging holes 34 arranged in a line at 
the time when the frame 1 is mounted at a given angle with the horizontal 
plane and the biasing force of the coiled spring 17 properly acts on the 
movable chassis 2a so as to hold the movable chassis 2a in the neutral 
equilibrium position. Thus, if the frame 1 is mounted in the player 
mounting position at an angle which is in a reverse relation with the 
angle shown in FIG. 10, and the movable chassis 2a is displaced from the 
neutral equilibrium position not in the direction shown in FIG. 10 but in 
the reverse direction, the adjustment can be performed by means of having 
the one end of the coiled spring 17 engaged the engaging hole 34 not far 
from, as shown in FIG. 12, but near to the upper plate 9 of the movable 
chassis 2a. With this adjustment, the biasing force of the coiled spring 
17 is decreased, so that the movable chassis 2a is moved from the position 
indicated in chain-dotted lines to the position indicated in solid lines 
in FIG. 12 with respect to the frame 1. Therefore, the positional 
deviation of the movable chassis 2a from the neutral equilibrium position 
with respect to the frame 1, which is in the reverse relation with the 
displacement shown in FIG. 10, can be corrected. And it is apparent that 
the operation reverse to that mentioned above will be enough to correct 
the position of the movable chassis 2a when the frame 1 is inclined 
further to the same side as that shown in FIG. 10. In other words, the 
correcting operation can be performed with only one mounting state 
correction mechanism 12, even if the frame 1 is mounted in the player 
mounting position sometimes at the normal angle with and sometimes at the 
reverse angle with the horizontal plane of the car. 
Industrial Applicability 
According to the present invention, a movable chassis mounted with an 
optical pickup, a turntable and the like is supported with a plurality of 
coiled springs which are joined with the respective positions of a frame, 
and at the same time, connected with the frame by a plurality of dampers 
so as to absorb the energy of vibrations of the movable chassis. 
Therefore, the slope of Q-value of the resonance region becomes small at 
the leading edge of the slope as compared with the conventional optical 
disk player only supported with rubber cushions, and the vibration 
isolation characteristic is improved, so that sound omissions tend not to 
occur. 
Furthermore, even if the optical disk player is mounted at any angle with 
the horizontal plane of the car, the principal part of the player, (that 
is, the movable chassis mounted with an optical pickup, a turntable and 
the like) can be always kept in the neutral equilibrium position, so that 
degradation of the vibration isolation characteristic of the dampers can 
be effectively prevented, and in addition, the collision between the frame 
and the movable chassis can be prevented without increasing the movable 
range of the movable chassis with respect to the frame.