Carriage lock mechanism of a magnetic recording/reproduction apparatus

A carriage lock mechanism is provided with a lock member mounted on a movable member of the carriage mechanism, a lock pawl for engaging with the lock member to lock the carriage mechanism, and a spring for biasing the lock pawl in a direction where the lock pawl engages with the lock member, wherein a sliding surface on which the distal end of the lock pawl slides during the lock operation is formed on the lock member, and the sliding surface has a shape corresponding to a locus of the lock member. If the movable member of the carriage mechanism is to be pivoted about a shaft, the sliding surface consists of an arc surface having the shaft as its center.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
The present invention relates to a carriage lock mechanism of a magnetic 
recording/reproduction apparatus, especially of a hard disk drive and, 
more particularly, to a carriage lock mechanism capable of preventing 
generation of fine dust particles due to friction between the components 
during a locking operation. 
(2) Description of the Prior Art 
A typical conventional hard disk apparatus and its carriage lock mechanism 
will be described below with reference to FIG. 1 and FIGS. 2A, 2B, and 2C. 
This conventional apparatus has magnetic disk 11, as shown in FIG. 1. Disk 
11 is coupled to and rotated by spindle motor 12. 
A carriage mechanism is provided near disk 11. This carriage mechanism 
includes head arm 13 and head arm supporting block 14, and magnetic head 9 
is mounted through suspension 10 to the distal end of arm 13. Head 9 is 
arranged near the upper surface of disk 11. Arm 13 and block 14 are 
supported to be rotatable about pivot shaft 15 in a plane parallel to the 
surface of disk 11. 
A voice coil motor is connected to block 14. This voice coil motor consists 
of coil 16 mounted on block 14 and magnet 17 mounted on a frame. Arm 13 
and block 14 are rotated by the voice coil motor, and head 10, mounted on 
the distal end of arm 13, is moved radially along disk 11 to perform a 
so-called seek operation. Thus, data is written in or read out from disk 
11 by head 9. 
This hard disk drive also has a carriage lock mechanism. When disk 11 is 
not rotated, head 9 is moved to a portion of disk 11 and this portion is 
not used for data recording. Disk 11 is kept fixed at this position by the 
above-mentioned carriage lock mechanism. Therefore, even when an external 
impact acts on the apparatus, damage to head 9 and disk 11 is prevented. 
The carriage lock mechanism has, as shown in FIGS. 2A, 2B, and 2C, lock 
member 18 mounted on block 14 and lock pawl 19 engaging with member 18 to 
perform a locking operation. Pawl 19 is supported by shaft 23, pivoted by 
a pivoting drive mechanism, and engaged with or disengaged from member 18. 
The pivoting drive mechanism for pawl 19 consists of spring 22 which 
biases pawl 19 in an engaging direction, i.e., a direction indicated by 
arrow 24 in FIG. 2A, and solenoid 21, which pivots pawl 19 in a 
disengaging direction, i.e., a direction indicated by arrow 26 in FIG. 2B. 
One end of the plunger inserted in solenoid 21 is connected to pawl 19. 
In such a carriage lock mechanism, upon deenergization of solenoid 21, pawl 
19 is pivoted in a direction of arrow 24 by a biasing force of spring 22, 
and hook 25, at the distal end of pawl 19, is engaged with member 18, 
thereby fixing the above carriage mechanism at a predetermined position, 
as shown in FIG. 2A. When the hard disk drive is in operation, solenoid 21 
is energized, pawl 19 is pivoted in a direction of arrow 26 in FIG. 2B 
against a biasing force of spring 22, and gap Gl is formed between the 
distal ends of pawl 19 and member 18, so that block 14 and arm 13 are 
pivotal. When the hard disk drive is stopped from an operating state, as 
shown in FIG. 2C solenoid 21 is deenergized, and block 14 and arm 13 are 
pivoted to predetermined positions by the voice coil motor. In this case, 
the distal end of pawl 19 abuts against an inclined portion of member 18, 
and when member 18 is pivoted together with block 14, the distal end of 
pawl 19 is pushed upward by a height G2 along the inclined portion of 
member 18 against the biasing force of spring 22. When member 18 is 
pivoted to a predetermined position, its distal end is engaged with pawl 
19. 
In such a magnetic recording/reproduction apparatus, especially in a hard 
disk drive, the magnetic recording density of the magnetic disk is very 
high, and, upon operation, a magnetic head floats above the magnetic disk. 
A gap between a surface of the magnetic disk and the magnetic head is very 
small on the order of, for example, 0.3 to 0.5 .mu.m. For this reason, a 
head crash occurs in the presence of even extremely small dust particles, 
destroying the recording data. In order to prevent the operation failure, 
such a hard disk drive is housed in a clean case having no particles 
therein. 
The above-mentioned carriage mechanism, the carriage lock mechanism, and 
the like are housed in the case. If a lubricant is applied to movable 
portions of these mechanisms, particles of the lubricant are formed in the 
clean case. For this reason, lubricants cannot be used for the mechanisms 
housed in the case. Thus, when the distal end of pawl 19 abuts against and 
slides along the inclined portion of member 18, fine dust particles are 
formed because of direct friction between metals, sometimes resulting in 
an operation failure of the hard disk drive due to these particles. 
Especially in this conventional apparatus, when the distal end of pawl 19 
is pushed upward along the inclined portion of member 18, an excess load 
is produced therebetween creating a large amount of particles. 
In order to eliminate the above drawbacks, the present invention provides a 
carriage lock mechanism capable of completely preventing formation of 
particles during operation. 
SUMMARY OF THE INVENTION 
A carriage lock mechanism according to the present invention comprises a 
lock member mounted on a movable member of a carriage mechanism, such as 
an arm supporting block, and a lock pawl engaging with this lock member. 
The lock pawl is biased by a spring in a direction for causing the pawl to 
engage with the lock member, and is driven by a drive mechanism against 
the above spring in a direction for causing the pawl to disengage from the 
lock member. A sliding surface on which the distal end of the above lock 
pawl slides during the locking operation, and an engaging portion, formed 
on an edge of the sliding portion, for engaging with the distal end of the 
above lock pawl, are formed on the lock member. The above sliding surface 
is formed along a moving locus of the above lock member. 
According to an embodiment of the present invention, the above lock member 
is so arranged as to be pivoted together with the arm supporting block, 
and its sliding surface is formed on a side surface of the lock member 
and, more particularly, on an arc surface having as its center a pivoting 
center of the lock member. Therefore, during the carriage lock operation, 
although the distal end of the lock pawl slides on the sliding surface of 
the lock member, the sliding surface does not push the distal end of the 
lock pawl upward against the biasing force of the spring because of its 
arc shape, so that the load produced during sliding is reduced to prevent 
formation of particles. According to another embodiment of the present 
invention, the sliding surface is formed on a plane parallel to a pivoting 
surface of the lock member. According to still another embodiment, when 
the distal end of the lock member slides on the sliding surface toward the 
engaging portion described above, the sliding surface is formed to incline 
"downward" with respect to the locus of the lock member, so that the lock 
pawl is moved in a direction to reduce the biasing force of the 
above-mentioned spring. 
In addition, in the embodiments of the present invention, the lock member 
and the lock pawl are formed of synthetic resin materials. These synthetic 
resin materials are easily deformed and have a large ductility, thereby 
rarely forming particles when the lock pawl slides against the lock member 
.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 3A to 3C show a carriage lock mechanism according to a first 
embodiment of the present invention. This carriage lock mechanism is used 
for a hard disk drive such as the apparatus disclosed in the conventional 
example described above. 
Reference numeral 14 denotes an arm supporting block which is arranged to 
be pivoted about pivot shaft 15. Lock plate member 30 arranged to be 
pivoted together with block 14 about shaft 15 is mounted on block 14. Lock 
pawl 19 is provided near lock plate member 30. Pawl 19 is pivotally 
supported by shaft 23, and hook 25 is formed at the distal end of pawl 19. 
Engaging portion 30a is formed at the distal end of lock plate member 30, 
with which hook 25 of pawl 19 engages, thereby locking block 14 at a 
predetermined position. 
Spring 22 is connected to pawl 19 to bias it, so that pawl 19 is pivoted in 
a direction in which its hook 25 engages with engaging portion 30a of lock 
plate member 30, i.e., a direction indicated by arrow 24 in FIG. 3A. 
Plunger 20, inserted in solenoid 21, is also connected to pawl 19. 
Solenoid 21 is energized to attract plunger 20, thereby pivoting pawl 19 
in a direction for disengaging, i.e., a direction indicated by arrow 26 in 
FIG. 3B against the biasing force of spring 22. 
Sliding surface 31, at the distal end of lock plate member 30, includes a 
surface along the locus of lock plate member 30, e.g., an arc surface 
having shaft 15 as its center in this embodiment. 
Both lock plate member 30 and pawl 19 are formed of synthetic resin 
materials; for example, lock plate member 30 is formed of a polycarbonate 
resin, and pawl 19 is formed of a polyamide resin. 
According to the first embodiment of the present invention having the above 
arrangement, hook 25 of pawl 19 engages with engaging portion 30a of lock 
plate member 30 in a locking state, as shown in FIG. 3A, thereby locking 
block 14 so as not to be pivoted. 
On the other hand, in an unlocked state, solenoid 21 is energized to 
atrract plunger 20 so that pawl 19 is pivoted against the biasing force of 
spring 22, as shown in FIG. 3B. In this state, gap G3 is formed between 
hook 25 of pawl 19 and distal end face 31 of lock plate member 30 so that 
block 14 is pivotal. 
When the mechanism is operated from unlocked to locked states, solenoid 21 
is deenergized, and block 14 is pivoted to a predetermined locked position 
by a voice coil motor. In this case, as shown in FIG. 3C, hook 25 of pawl 
19 abuts against sliding surface 31 of lock plate member 30 by the biasing 
force of spring 22. In this condition, when lock plate member 30 is 
pivoted together with block 14 and engaging portion 30a of lock plate 
member 30 corresponds to hook 25 of pawl 19, hook 25 engages with engaging 
portion 30a to complete locking by the biasing force of spring 22, as 
shown in FIG. 3A. Since surface 31 is formed along the locus of lock plate 
member 30, i.e., the arc surface having shaft 15 as its center, pawl 19 is 
not pivoted against the biasing force of spring 22 when hook 25 of pawl 19 
slides along surface 31. Thus, the load between hook 25 and surface 31 is 
so small that formation of particles by friction between the materials can 
be prevented. 
In this embodiment, lock plate member 30 and pawl 19 are formed of 
synthetic resin materials. The synthetic resin materials are easily 
deformed and have a large ductility. Even when pawl 19 slides along lock 
plate member 30 without a lubricant therebetween, only a small frictional 
force is generated and dust particles are rarely formed. 
FIG. 4 shows a second embodiment of the present invention. In this 
embodiment, a surface of hook 25 at the distal end of pawl 19, which 
opposes surface 31 of lock plate member 30, is arc surface 25a 
corresponding to surface 31. 
According to this embodiment, surface 31 of lock plate member 30 uniformly 
contacts the entire surface 25a of hook 25 of pawl 19 to generate a low 
pressure therebetween, thereby further preventing friction and formation 
of particles. 
FIG. 5 shows a third embodiment of the present invention. In this 
embodiment, lock pawl 40 is guided and linearly moved by a pair of guides 
43 to engage with and disengage from lock plate member 30. Note that 
arc-shaped sliding surface 41 and step 42 are formed at the distal end of 
pawl 40. Surface 41 abuts against and slides on surface 31 of lock plate 
member 30, and hook 42 engages with engaging portion 30a of lock plate 
member 30. Plunger 20 inserted in solenoid 21 is connected to pawl 40 
which is biased by spring 44 in a direction for causing pawl 40 to engage 
with lock plate member 30. 
FIGS. 6 to 8 show a fourth embodiment of the present invention. In this 
embodiment, an upper surface of lock member 50, mounted on block 14, 
includes sliding surface 56, arranged on a plane parallel to a plane on 
which member 50 rotates about shaft 15. Engaging step 50a is formed at an 
edge of surface 56. Pivot shaft 52 is disposed above surface 56 of member 
50 and is rotatably supported by a pair of bearings 55. Lock pawl 51 is 
mounted on the distal end of shaft 52, and hook step 51a and sliding 
surface 57 are formed at the distal end of lock pawl 51. Lever 53 is 
mounted on the proximal end of shaft 52 and faces downward. Plunger 20 is 
connected to the distal end of lever 53. Shaft 52 is biased by spring 54 
in a direction in which its pawl 51 engages with member 50. 
The operation of this embodiment is as follows. Solenoid 21 is energized 
and plunger 20 is attracted. Upon the interruption of the power supply, 
solenoid 21 is in a non-energized state. Plunger 20 is rotated in a 
direction indicated by arrow 62 and link 53, coupled by pin 60, is rotated 
in a direction indicated by arrow 61. (Shaft 52 is fixed to lever 53 and 
held by bearing 55.) Pawl 51, fixed to the shaft, is rotated in a 
direction of arrow 58, so that the portion of surface 57 is brought into 
engagement with the portion of surface 56 of lock member 50. 
Arm support block 14 is rotated in a direction of arrow 63 simultaneously 
with the interruption of the power supply. Lock member 50, mounted to arm 
support block 14, is also rotated. Lock member 50, while contacting the 
portion of surface 57 of pawl 51, continues its rotation. When step 50a is 
brought to a position corresponding to step 51a of pawl 51, of pawl 51 is 
rotated in the direction of an arrow 58 into locking engagement with step 
50a. 
Note that the present invention is not limited to the above embodiments. It 
is obvious that various changes and modifications can be made by the 
skilled in the art without departing from the spirit and scope of the 
present invention.