Lock device having an improved lock member

A lock device includes a frame which has an opening and a fixed portion internally provided therein. A lid member is hinged to the frame, the lid member being rotatable between an open position and a closed position, the opening of the frame being opened by the lid member at the open position and closed by the lid member at the closed position. A lock member locks the lid member to the frame when the lid member is at the closed position, the lock member including a connecting unit and a rotating unit, the connecting unit configured to be connected to the fixed portion so as to lock the lid member to the frame, the rotating unit configured to be engaged with the connecting unit, the rotating unit actuating the connecting unit so as to connect the connecting unit to the fixed portion when the rotating unit is depressed, the rotating unit actuating the connecting unit so as to lock the lid member to the frame when the rotating unit is rotated, wherein the rotation of the rotating unit is allowed by a disengagement of the rotating unit from the connecting unit caused by the depression of the rotating unit.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
The present invention relates to a lock device which locks a lid member 
hinged to a frame, the lid member being rotatable between an open position 
and a closed position such that an insertion opening of the frame is 
opened by the lid member at the open position and closed by the lid member 
at the closed position. 
(2) Description of the Related Art 
There is an electronic device frame to which an access door is hinged so as 
to open or close an insertion opening of the frame. In order to ensure a 
sealing performance of the frame when the insertion opening is closed, a 
lock device which is provided to lock the access door in the frame is 
known. 
A conventional lock device of the above type includes a rotatable lever 
with a lock plate attached thereto, and a fixed member provided at an 
internal portion of the frame. The rotatable lever is provided on an 
external surface of the access door, and the lock plate is provided inside 
the access door. When the lever on the external surface of the access door 
is rotated to a locked position, the lock plate inside the access door is 
also rotated so that the lock plate is connected to the fixed member. In 
this condition, the conventional lock device locks the access door of the 
frame when the access door is at the closed position. A detailed 
description will be given of a frame to which a conventional lock device 
is applied, with reference to FIG. 12 through FIG. 14D. 
FIG. 12 shows a frame 100 to which a conventional lock device is applied. 
The frame 100 is an enclosure case which accommodates an electronic device 
in which electronic circuits and parts are arranged therein. 
As shown in FIG. 12, the frame 100 generally includes a frame main part 
112, an insertion opening 113, and an access door 118. The access door 118 
is a lid member hinged to the main part 112 by using a pair of hinges 114. 
The access door 118 is rotatable between an open position and a closed 
position so that the insertion opening 113 is opened by the access door 
118 at the open position and closed by the access door 118 at the closed 
position. A lock member 110 is attached to the access door 118. The lock 
member 110 includes a rotatable lever with a lock plate attached thereto, 
which will be described below. 
FIG. 13A and FIG. 13B show a construction of the lock member 110 of the 
conventional lock device of FIG. 12. FIG. 13A is a perspective view of the 
lock member 110, and FIG. 13B is a side view of the lock member 110. 
As shown in FIG. 13A and FIG. 13B, the lock member 110 includes a rotatable 
lever 126, a lock plate 127, and a shaft 130. The shaft 130 is provided in 
the form of a cylindrical slender rod. The lever 126 and the lock plate 
127 are secured to both ends of the shaft 130 such that the lever 126 and 
the lock plate 127 extend in opposite parallel directions from the ends of 
the shaft 130. When the lever 126 is rotated around the shaft 130, the 
lock plate 127 is also rotated around the shaft 130 together with the 
lever 126. 
In the conventional lock device of FIG. 12, in order to close the insertion 
opening 113 of the frame 100, the access door 118 is upwardly rotated on 
the hinges 114 to the closed position which is shown in FIG. 12. On the 
other hand, in order to open the insertion opening 113, the access door 
118 is downwardly rotated on the hinges 114 to the open position which is 
not shown in the drawings. 
FIG. 14A and FIG. 14B show a condition of the conventional lock device of 
FIG. 12 when the rotatable lever is set in an unlocked position. FIG. 14A 
is a front view of the conventional lock device, and FIG. 14B is a 
cross-sectional side view of the conventional lock device. 
As shown in FIG. 14A and FIG. 14B, the access door 118 is set in the closed 
position, and the lever 126 is set in the unlocked position. In order to 
lock the access door 118 at the closed position, the lever 126 is 
downwardly rotated around the shaft 130 to a locked position in a 
direction indicated by the arrow "X" in FIG. 14A. Hereinafter, a condition 
of the lever 126 when it is set in the unlocked position will be called a 
horizontal condition, and a condition of the lever 126 when it is set in 
the locked position will be called an upright condition. 
The conventional lock device includes a fixed member 125 of a thin plate 
material which is provided at an internal upper portion of the main part 
112, as shown in FIG. 14A and FIG. 14B. When the lever 126 is set in the 
unlocked position, the lock plate 127 at the other end of the shaft 130 is 
separated from the fixed member 125 of the main part 112. 
FIG. 14C and FIG. 14D show a condition of the conventional lock device of 
FIG. 12 when the rotatable lever is set in the locked position. FIG. 14C 
is a front view of the conventional lock device, and FIG. 14D is a 
cross-sectional side view of the conventional lock device. 
As shown in FIG. 14C and FIG. 14D, when the lever 126 is set in the locked 
position, the lock plate 127 at the other end of the shaft 130 is 
connected to the fixed member 125 of the main part 112. As the lock plate 
127 of the lock member 110 is connected to the fixed member 125, the 
access door 118 at the closed position is locked by the lock member 110, 
which prevents the access door 118 from being rotated on the hinges 114 to 
the open position. 
However, when the frame 100 is used with the above-described conventional 
lock device, some problems may arise. 
In the conventional lock device of FIG. 12, before the access door 118 is 
rotated on the hinges 114 to the closed position, the lever 126 must be 
set in the unlocked position (or the horizontal condition) so as to avoid 
the interference of the lock plate 127 with the main part 112. After the 
access door 118 is completely rotated to the closed position at which the 
access door 118 and the main part 112 are fitted to each other, the lever 
126 must be set in the locked position (or the upright condition) so as to 
ensure a sealing performance of the frame 100. If the lever 126 is set in 
the upright condition before rotating the access door 118 on the hinges 
114 to the closed position, the lock plate 127 at the other end of the 
shaft 130 may interfere with the main part 112. It is difficult for the 
conventional lock device in such a condition to completely rotate the 
access door 118 on the hinges 114 to the closed position without 
interference. Hence, it is difficult for the conventional lock device in 
such a condition to ensure the sealing performance of the frame 100. 
In the conventional lock device of FIG. 12, when the access door 118 is 
locked by the lock member 110, the rotation of the access door 118 on the 
hinges 114 toward the open position is inhibited by the connection of the 
lock plate 127 and the fixed member 125. In order to maintain the lever 
128 in the locked position or the upright condition, it is necessary that 
an adequate level of a frictional force between the lock plate 127 and the 
fixed member 125 be exerted. If the adequate level of the frictional force 
is not exerted, the lock plate 127 is easily disconnected from the fixed 
member 125 so that the lever 128 is rotated toward the unlocked position 
or the horizontal condition. This causes the access door 118 to be loosely 
rotated on the hinges 114 toward the open position. Hence, it is difficult 
for the conventional lock device in such a condition to ensure the sealing 
performance of the frame 100. 
Further, when the frame 100 is used with the conventional lock device over 
an extended period of time, the relative position of the lock plate 127 to 
the fixed member 125 is likely to deviate from the original position due 
to vibrations or deformations of the frame 100. If the relative position 
of the lock plate 127 to the fixed member 125 deviates such that the lock 
plate 127 interferes with the fixed member 125 when the lever 126 is 
located at an intermediate position between the unlocked position and the 
locked position, it is difficult to rotate the lever 126 to the locked 
position. Hence, it is difficult for the conventional lock device in such 
a condition to ensure the sealing performance of the frame 100. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide an improved lock device in 
which the above-described problems are eliminated. 
Another object of the present invention is to provide a lock device in 
which a locking operation of a lock member to lock a lid member is allowed 
only after an insertion opening of a frame is completely closed by the lid 
member. 
The above-mentioned objects of the present invention are achieved by a lock 
device comprising: a frame which has an opening and a fixed portion 
internally provided therein; a lid member which is hinged to the frame, 
the lid member being rotatable between an open position and a closed 
position, the opening of the frame being opened by the lid member at the 
open position and closed by the lid member at the closed position; and a 
lock member which locks the lid member to the frame when the lid member is 
at the closed position, the lock member including a connecting unit and a 
rotating unit, the connecting unit configured to be connected to the fixed 
portion so as to lock the lid member to the frame, the rotating unit 
configured to be engaged with the connecting unit, the rotating unit 
actuating the connecting unit so as to connect the connecting unit to the 
fixed portion when the rotating unit is depressed, the rotating unit 
actuating the connecting unit so as to lock the lid member to the frame 
when the rotating unit is rotated, wherein the rotation of the rotating 
unit is allowed by a disengagement of the rotating unit from the 
connecting unit caused by the depression of the rotating unit. 
In the lock device of the present invention, when locking the lid member at 
the closed position, an operator successively performs a connecting 
operation of the lever and a rotating operation of the lever. A locking 
operation of the lock member to lock the lid member is allowed only after 
the insertion opening of the frame main part is completely closed by the 
lid member. It is possible for the lock device of the present invention to 
prevent the rotating operation of the lever from being performed before 
the insertion opening is completely closed by the lid member. Further, the 
lock device of the present invention is effective in providing reliability 
when the insertion opening of the frame main part is completely closed by 
the lid member. If the relative position of the connecting unit and the 
frame main part deviates from the original position due to vibrations or 
deformations of the frame main part, the lock device of the present 
invention in such a condition is effective in providing reliability when 
the insertion opening of the frame main part is completely closed by the 
lid member. It is possible for the lock device of the present invention to 
ensure a sealing performance of the frame main part.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A description will now be given of the preferred embodiments of the present 
invention with reference to the accompanying drawings. 
FIG. 1 shows a video tape recorder 1 to which one embodiment of the lock 
device of the present invention is applied. The video tape recorder 1 is 
designed for installation in an aircraft. The video tape recorder 1 
generally has a frame main part 12, a pair of hinges 14, a set of control 
switches 16, an access door 18, and a lock member 10. 
The main part 12 is an enclosure case which accommodates electronic 
circuits and parts arranged within the video tape recorder 1. The main 
part 12 has an insertion opening 13 provided therein. A video tape 
cassette (not shown) can be inserted into or withdrawn from the video tape 
recorder 1 through the insertion opening 13 when the insertion opening 13 
is opened. 
The control switches 16 are provided on a front surface of the main part 
12. The control switches 16 include a power switch, a record switch, a 
play switch, a stop switch, a fast-forward switch, a rewind switch, and 
others. 
Generally, an electronic device installed in an aircraft is devised to 
withstand vibrations or impacts to which electronic circuits and parts of 
the electronic device are subjected. The main part 12 in the present 
embodiment is constructed in a hermetical structure by using a metallic 
material having an adequate stiffness, in order to protect the electronic 
circuits and parts of the video tape recorder 1 against the vibrations or 
the impacts which may be experienced by the aircraft. 
In addition, the main part 12 in the present embodiment is provided with a 
capability of electromagnetic interference prevention so as to protect the 
electronic circuits and parts of the video tape recorder 1 against 
electromagnetic waves which may be experienced by the aircraft. For 
example, the main part 12 is produced by using an aluminum alloy, and a 
copper plating layer is formed on the surface of the main part 12. 
The access door 18 is produced by using a metallic material which is the 
same as the material of the main part 12 of the video tape recorder 1. The 
access door 18 is provided with the capability of electromagnetic 
interference prevention similar to the main part 12. The lock member 10 is 
provided on the access door 18. The access door 18 is a lid member hinged 
to the main part 12 by using the pair of hinges 14. The access door 18 is 
rotatable between an open position and a closed position so that the 
insertion opening 13 is opened by the access door 18 at the open position 
and closed by the access door 18 at the closed position. In addition, a 
pad 24 of an urethane sponge material is attached to the peripheral 
portion of the access door 18 which is fitted to the main part 12 when the 
access door 18 is rotated to the closed position. The pad 24 functions to 
absorb an impact when the access door 18 at the closed position is fitted 
to the main part 12, and to provide an increased sealing of the main part 
12. 
In order to allow a video tape cassette to be inserted into or withdrawn 
from the video tape recorder 1 through the insertion opening 13, the 
access door 18 is downwardly rotated to the open position. When the access 
door 18 is set at the open position, the insertion opening 13 of the main 
part 12 is opened by the access door 18. 
In the lock device of the present embodiment, the lock member 10 includes a 
rotating unit and a connecting unit, and the connecting unit and the 
rotating unit are configured such that the locking operation of the lock 
member 10 to lock the access door 18 is allowed only after the insertion 
opening 13 of the frame main part 12 is completely closed by the access 
door 18. The rotating unit and the connecting unit of the lock member 10 
are provided on the access door 18. 
FIG. 2 shows a rotating unit 20 of the lock member 10 in the lock device of 
FIG. 1. 
As shown in FIG. 2, the rotating unit 20 includes a lever 26, a spring 28, 
a shaft 30, and a cam 32. The shaft 30 is provided in the form of a 
cylindrical slender rod. The cam 32 includes a first disk and a second 
disk which are integrally formed with an interconnecting shaft. A 
configuration of the cam 32 will be described below. The spring 28 is a 
helical compression spring having a coil inside diameter that is slightly 
larger than an outside diameter of the shaft 30. 
FIG. 3A, FIG. 3B and FIG. 3C show a configuration of the cam 32 of the 
rotating unit 20. FIG. 3A is a perspective view of the cam 32, FIG. 3B is 
a front view of the cam 32, and FIG. 3C is a side view of the cam 32. 
As shown in FIG. 3A through FIG. 3C, the cam 32 includes a first disk 32a 
and a second disk 32b which have different diameters and are integrally 
formed with an interconnecting shaft. The first disk 32a and the second 
disk 32b are fixed at their centers to both ends of the shaft. The first 
disk 32a has a diameter that is larger than a diameter of the second disk 
32b. The first disk 32a includes a cut-out portion 33 at a peripheral 
position of the first disk 32a. The first disk 32a includes a stepped 
portion 34 on an internal surface of the first disk 32a adjacent to the 
cut-out portion 33. The stepped portion 34 of the first disk 32a confronts 
an internal surface of the second disk 32b. The first disk 32a includes a 
V-groove 35 on an external surface of the first disk 32a at a peripheral 
position thereof that is almost opposite to the stepped portion 34 with 
respect to the center of the first disk 32a. The V-groove 35 and the 
cut-out portion 33 are spaced from each other by about 90 degrees around 
the center of the first disk 32a. The first disk 32a is provided with a 
slanted wall on the side of the external surface in a region between the 
V-groove 35 and the cut-out portion 33, and the slanted wall of the first 
disk 32a has a thickness that is gradually reduced in the direction from 
the V-groove 35 to the cut-out portion 33. 
Referring back to FIG. 2, the rotating unit 20 is arranged such that the 
lever 26 and the spring 28 are provided on an external surface of the 
access door 18, the cam 32 is provided on an internal surface of the 
access door 18, and the shaft 30 on which the spring 28 is mounted is 
passed through a hole of the access door 18. The lever 26 and the cam 32 
are secured to the ends of the shaft 30. 
In the rotating unit 20 of the lock member 10, the lever 26 and the cam 32 
are secured to the ends of the shaft 30, and the spring 28 is interposed 
between the lever 26 and the external surface of the access door 18. The 
spring 28 exerts an actuating force on the lever 26 so as to separate the 
lever 26 from the access door 18. When no external force acts, the cam 32 
at the opposite end of the shaft 30 is pulled toward the internal surface 
of the access door 18 by the actuating force of the spring 28 on the 
external surface of the access door 18. 
The configuration of the cam 32 shown in FIG. 3A through FIG. 3C is 
described above for the purpose of giving an example. In the lock device 
of the present invention, the configuration of the cam of the rotating 
unit is not limited to this example. 
FIG. 15A, FIG. 15B and FIG. 15C show a configuration of another cam 132 of 
the rotating unit in the lock device of FIG. 1. FIG. 15A is a perspective 
view of the cam 132, FIG. 15B is a front view of the cam 132, and FIG. 15C 
is a side view of the cam 132. 
As shown in FIG. 15A through FIG. 15C, the cam 132 is a variation of the 
cam 32 of FIG. 3A through FIG. 3C. The cam 132 includes a first disk 132a 
and a second disk 132b which have the same diameter and are integrally 
formed with an interconnecting shaft. The first disk 132a includes a 
cut-out portion 133 at a peripheral position of the first disk 132a. The 
first disk 132a includes no stepped portion on the first disk 132a 
adjacent to the cut-out portion 133. The first disk 132a includes a 
radially-extending groove 135 on an external surface of the first disk 
132a at a peripheral position thereof. The groove 135 and the cut-out 
portion 133 are spaced from each other by about 90 degrees around the 
center of the first disk 132a. The first disk 132a is provided with a 
slanted wall on the side of the external surface thereof in a region 
between the groove 135 and the cut-out portion 133, and the slanted wall 
of the first disk 132a has a thickness that is gradually reduced in the 
direction from the groove 135 to the cut-out portion 133. 
It is a matter of course that the cam 132 of FIG. 15A through FIG. 15C may 
be incorporated in the lock device of FIG. 1 in a manner similar to the 
cam 32 of FIG. 3A through FIG. 3C. 
Next, FIG. 4A through FIG. 6 show the elements of the connecting unit of 
the lock member 10 of FIG. 1. The connecting unit 22 in the present 
embodiment includes a supporting base 36 and a cam engaging part 44. 
FIG. 4A is a perspective view of the supporting base 36 of the connecting 
unit 22 in the present embodiment, and FIG. 4B is a top view of the 
supporting base 36 of the connecting unit 22 in the present embodiment. 
The supporting base 36 is secured to the internal surface of the access 
door 18 at a given position. 
As shown in FIG. 4A and FIG. 4B, the supporting base 36 includes a 
rectangular plate 37, a cylindrical stopper 40, a pair of arm portions 38a 
and 38b, and a laterally extending shaft 42. The plate 37 is secured to 
the internal surface of the access door 18 at the given position. The 
stopper 40 is embedded in the plate 37 at a central position of the plate 
37. The stopper 40 projects from an internal surface of the plate 37 in a 
direction parallel to the arm portions 38a and 38b. The arm portions 38a 
and 38b extend from side edges of the plate 37 in directions perpendicular 
to the plate 37. The shaft 42 is laterally provided between end portions 
of the arm portions 38a and 38b and extends in a lateral direction 
parallel to the internal surface of the plate 37. 
A ball 41 is provided at a top of the stopper 40 on the supporting base 36, 
and the ball 41 is engaged with the external surface of the first disk 32a 
of the cam 32 when the cam 32 is rotated around the shaft 30. The ball 41 
is rotatably fitted into the stopper 40 in order to reduce friction 
between the ball 41 and the cam 32 when the cam 32 is rotated. Hence, the 
ball 41 functions as a ball bearing that movably supports the cam 32 when 
the ball 41 is engaged with the cam 32. Further, a screw (not shown) is 
fastened to a threaded base of the stopper 40 on the side opposite to the 
ball 41, and a leading edge of the screw fastened to the stopper 40 is 
brought into contact with the bottom of the ball 41. In the present 
embodiment, a height of the ball 41 that projects from the top of the 
stopper 40 is determined by adjusting the amount of fastening the screw to 
the stopper 40. 
In the present embodiment, the stopper 40 of the supporting base 36 is 
fitted in the cut-out portion 33 of the cam 32 of the rotating unit 20. 
When the stopper 40 is fitted in the cut-out portion 33 of the cam 32, the 
rotation of the cam 32 and the lever 27 around the shaft 30 is inhibited 
by the engagement between the cutout portion 33 of the rotating unit 20 
and the stopper 40 of the connecting unit 22. 
FIG. 5A is a perspective view of the cam engaging part 44 of the connecting 
unit 22 in the present embodiment, and FIG. 5B is a side view of the cam 
engaging part 44 of the connecting unit 22 in the present embodiment. 
As shown in FIG. 5A and FIG. 5B, in the cam engaging part 44, a pair of 
side walls 46a and 46b which extend from side edges of a rectangular base 
plate in directions perpendicular to the base plate are provided. A cam 
engaging shaft 48 is provided between the side walls 46a and 46b, and 
extends in a lateral direction parallel to the base plate. The cam 
engaging shaft 48 is a cylindrical slender rod. The side wall 46a includes 
a hole 50a and a connecting portion 52a, and the side wall 46b includes a 
hole 50b and a connecting portion 52b. 
FIG. 6 shows the connecting unit 22 in which the cam engaging part 44 is 
attached to the supporting base 36. 
As shown in FIG. 6, the shaft 42 of the supporting base 36 is inserted at 
both ends into the holes 50a and 50b of the cam engaging part 44. By the 
connection of the shaft 42 and the holes 50a and 50b, the cam engaging 
part 44 is rotatably supported on the supporting base 36. As indicated by 
the arrow "Y" in FIG. 6, the cam engaging part 44 is rotatable around the 
shaft 42. 
FIG. 7 shows a part of the lock member 10 in which the cam engaging part 44 
of the connecting unit 22 is engaged with the cam 32 of the rotating unit 
20. 
As shown in FIG. 7, when the cam engaging part 44 is engaged with the cam 
32, the cam engaging shaft 48 is fitted in the internal space between the 
first disk 32a and the second disk 32b of the cam 32. A movement of the 
cam 32 in the axial direction of the shaft 30 is transmitted to the cam 
engaging part 44 through the connection of the shaft 48 and the cam 32. 
Next, a description will be given of the operation of the lock device of 
the present embodiment with reference to FIG. 8A through FIG. 11D. 
In the lock device of the present embodiment, in order to lock the access 
door 18 at the closed position, a connecting operation of the lever 26 and 
a rotating operation of the lever 26 are successively performed by an 
operator of the video tape recorder 1. In the present embodiment, a pair 
of fixed portions 54a and 54b are provided at internal upper positions of 
the frame main part 12 (which will be described below). 
When the connecting operation of the lever 26 is performed by the operator, 
the lever 26 on the external surface of the access door 18 is depressed in 
the axial direction of the shaft 30 against the actuating force of the 
spring 28. By the depression of the lever 26, the cam 32 at the other end 
of the shaft 30 is also moved in the axial direction of the shaft 30. This 
movement of the cam 32 is transmitted to the cam engaging part 44 through 
the connection of the shaft 48 and the cam 32. The connecting portions 52a 
and 52b of the cam engaging part 44 mounted on the internal surface of the 
access door 18 are connected to the fixed portions 54a and 54b of the 
frame main part 12 by the engagement of the rotating unit 20 and the 
connecting unit 22. A detailed description of the operation of the lock 
device of the present embodiment when the connecting operation of the 
lever 26 is performed by the operator will be given below. 
When the rotating operation of the lever 26 is performed by the operator 
after the end of the connecting operation, the lever 26, which is 
depressed toward the access door 18, is rotated to the locked position 
around the shaft 30. After the rotating operation is performed, the lock 
member 10 locks the access door 18 at the closed position. A detailed 
description of the operation of the lock device of the present embodiment 
when the rotating operation of the lever 26 is performed by the operator 
will be given below. 
FIG. 8A and FIG. 8B show the lock device of the present embodiment when the 
access door 18 is set in the open position. FIG. 8A is a perspective view 
of the lock device of the present embodiment in this condition, and FIG. 
8B is a side view of the lock device of the present embodiment in this 
condition. 
As shown in FIG. 8A and FIG. 8B, the access door 18 is downwardly rotated 
on the hinges 14 so that the access door 18 is set in the open position. 
The insertion opening 13 of the frame main part 12 is opened by the access 
door 18. The hinges 14 attached to the access door 18 downwardly extend 
from the pivotal points on the frame main part 13. In this condition, a 
video tape cassette (not shown) can be inserted into or withdrawn from the 
video tape recorder 1. The spring 28 exerts the actuating force on the 
lever 26 so as to separate the lever 26 from the external surface of the 
access door 18. The cam 32 at the opposite end of the shaft 30 is pulled 
toward the internal surface of the access door 18 by the actuating force 
of the spring 28 on the external surface of the access door 18. 
FIG. 9A and FIG. 9B show the lock device of the present embodiment when the 
access door 18 is set in the closed position with the lever 26 being set 
in the unlocked position. FIG. 9A is a perspective view of the lock device 
of the present embodiment in this condition, and FIG. 9B is a side view of 
the lock device of the present embodiment in this condition. 
As shown in FIG. 9A and FIG. 9B, the access door 18 is upwardly rotated on 
the hinges 14 so that the access door 18 is set in the closed position. 
The access door 18 in this condition matches with the frame main part 12. 
The insertion opening 13 of the frame main part 12 is closed by the access 
door 18. The spring 28 exerts the actuating force on the lever 26 so as to 
separate the lever 26 from the external surface of the access door 18. The 
cam 32 at the opposite end of the shaft 30 is pulled toward the internal 
surface of the access door 18 by the actuating force of the spring 28 on 
the external surface of the access door 18. In this condition, the 
connecting portions 52a and 52b of the cam engaging part 44 mounted on the 
internal surface of the access door 18 are disconnected from the fixed 
portions 54a and 54b of the frame main part 12 as shown in FIG. 9B. That 
is, the insertion opening 13 of the frame main part 12 is not completely 
closed by the access door 18 in this condition. Further, in this 
condition, the stopper 40 on the supporting base 36 inside the access door 
18 is fitted in the cut-out portion 33 of the cam 32, and the rotation of 
the cam 32 and the lever 26 around the shaft 30 is inhibited by the 
engagement between the cut-out portion 33 of the rotating unit 20 and the 
stopper 40 of the connecting unit 22. That is, the locking operation of 
the lock member 10 to lock the access door 18 is inhibited at this time. 
FIG. 10A and FIG. 10B show the lock device of the present embodiment when 
the access door 18 is set in the closed position and the connecting 
operation of the lever 26 is performed. FIG. 10A is a perspective view of 
the lock device of the present embodiment in this condition, and FIG. 10B 
is a side view of the lock device of the present embodiment in this 
condition. 
As shown in FIG. 10A and FIG. 10B, when the connecting operation of the 
lever 26 is performed by the operator, the lever 26 on the external 
surface of the access door 18 is depressed in the axial direction of the 
shaft 30 against the actuating force of the spring 28. By the depression 
of the lever 26, the cam 32 at the other end of the shaft 30 is also moved 
in the axial direction of the shaft 30 toward the inside of the frame main 
part 12. This movement of the cam 32 is transmitted to the cam engaging 
part 44 through the connection of the shaft 48 and the cam 32. At this 
time, the shaft 48, which is interposed between the first disk 32a and the 
second disk 32b, is moved together with the cam 32 in the axial direction 
of the shaft 30 toward the inside of the frame main part 12. 
As previously described, the shaft 42 of the supporting base 36 on the 
internal surface of the access door 18 is inserted into the holes 50a and 
50b of the cam engaging part 44. By the connection of the shaft 42 and the 
holes 50a and 50b, the cam engaging part 44 is rotatably supported on the 
supporting base 36, and the cam engaging part 44 is rotatable around the 
shaft 42. As the shaft 48 is moved in the axial direction of the shaft 30 
toward the inside of the frame main part 12, the cam engaging part 44 on 
which the shaft 48 is mounted is upwardly rotated around the shaft 42, as 
indicated the arrow "Y" in FIG. 10B. Hence, the connecting portions 52a 
and 52b of the cam engaging part 44 are connected to the fixed portions 
54a and 54b of the frame main part 12 by the engagement of the rotating 
unit 20 and the connecting unit 22. That is, the insertion opening 13 of 
the frame main part 12 is completely closed by the access door 18. 
Further, when the connecting operation of the lever 26 is performed, the 
lever 26 is depressed in the axial direction of the shaft 30, and the cam 
32 is moved in the axial direction of the shaft 30 toward the inside of 
the frame main part 12. By this movement of the cam 32, the cut-out 
portion 33 of the cam 32 is disconnected from the stopper 40 on the 
supporting base 36. At this time, the rotation of the lever 26 and the cam 
32 around the shaft 30 is allowed by the disengagement of the rotating 
unit 20 from the connecting unit 22 (or the disengagement of the cut-out 
portion 33 from the stopper 40). That is, the locking operation of the 
lock member 10 to lock the access door 18 is possible. 
FIG. 11A, FIG. 11B, FIG. 11C and FIG. 11D show the operation of the lock 
member 10 in the lock device of the present embodiment. 
FIG. 11A shows a condition of the lock member 10 when neither the 
connecting operation nor the rotating operation is performed to the lever 
26. FIG. 11B shows a condition of the lock member 10 when the connecting 
operation of the lever 26 is performed. As shown in FIG. 11B, the lever 26 
on the external surface of the access door 18 is depressed in the axial 
direction of the shaft 30 against the actuating force of the spring 28. By 
the depression of the lever 26, the cam 32 at the other end of the shaft 
30 is also moved in the axial direction of the shaft 30 toward the inside 
of the frame main part 12. By this movement of the cam 32, the cut-out 
portion 33 of the cam 32 is disconnected from the stopper 40 on the 
supporting base 36, and the rotation of the lever 26 and the cam 32 around 
the shaft 30 is allowed by the disengagement of the cut-out portion 33 
from the stopper 40. 
FIG. 11C shows a condition of the lock member 10 when the rotating 
operation of the lever 26 is performed after the end of the connecting 
operation. As shown in FIG. 11C, while the lever 26 is depressed toward 
the external surface of the access door 18, the lever 26 is rotated around 
the shaft 30 in a direction indicated by the arrow "Z" in FIG. 11C. 
FIG. 11D shows a condition of the lock member 10 after the rotating 
operation of the lever 26 is performed. As shown in FIG. 11D, the lever 26 
is rotated about 90 degrees around the shaft 30 to the locked position. In 
accordance with the rotation of the lever 26, the cam 32 is rotated around 
the shaft 30, and the V-groove 35 at the peripheral position on the 
external surface of the first disk 32a is fitted to the ball 41 on the top 
of the stopper 40 on the supporting base 36. The rotating operation of the 
lever 26 is stopped by the connection of the V-groove 35 and the ball 41. 
In the present embodiment, the ball 41 is rotatably fitted into the stopper 
40 in order to reduce friction between the ball 41 and the cam 32 when the 
cam 32 is rotated. The ball 41 functions as a ball bearing that movably 
supports the cam 32 when the ball 41 is engaged with the cam 32. Further, 
the screw (not shown) is fastened to the threaded base of the stopper 40 
on the side opposite to the ball 41, and the leading edge of the screw 
fastened to the stopper 40 is brought into contact with the bottom of the 
ball 41. The height of the ball 41 that projects from the top of the 
stopper 40 is determined by adjusting the amount of fastening the screw to 
the stopper 40. Further, the slanted wall of the first disk 32a has a 
thickness that is gradually reduced in the direction from the V-groove 35 
to the cut-out portion 33. Therefore, when the lever 26 is rotated to the 
locked position while the lever 26 is depressed toward the access door 18, 
the cam 32 can be smoothly rotated around the shaft 30 until the V-groove 
35 of the first disk 32a is fitted to the ball 41 on the top of the 
stopper 40. 
As described above, when locking the access door 18 at the closed position 
in the lock device of the present embodiment, the operator successively 
performs the connecting operation of the lever 26 and the rotating 
operation of the lever 26. The locking operation of the lock device of the 
present embodiment to lock the access door 18 is allowed only after the 
insertion opening 13 of the frame main part 12 is completely closed by the 
access door 18. It is possible for the lock device of the present 
embodiment to prevent the rotating operation of the lever 26 from being 
performed before the insertion opening 13 is completely closed by the 
access door 18. 
Further, the first disk 32a of the cam 32, which is engaged with the 
stopper 40, has the slanted wall in the region between the V-groove 35 and 
the cut-out portion 33 on the side of the external surface, and the 
slanted wall of the first disk 32a has a thickness that is gradually 
reduced in the direction from the V-groove 35 to the cut-out portion 33. 
When the lever 26 is rotated to the locked position after the end of the 
connecting operation, the cam 32 can be gradually separated from the 
internal surface of the access door 18 in accordance with the rotation of 
the cam 32 around the shaft 30 from the cut-out portion 33 to the V-groove 
35. The shaft 48, which is interposed between the first disk 32a and the 
second disk 32b, can be gradually moved together with the cam 32 in the 
axial direction of the shaft 30 toward the inside of the frame main part 
12. The cam engaging part 44 on which the shaft 48 is mounted can be 
gradually rotated around the shaft 42 by the gradual movement of the shaft 
48. Hence, the connecting portions 52a and 52b of the cam engaging part 44 
can be smoothly connected to the fixed portions 54a and 54b of the frame 
main part 12 by the engagement of the rotating unit 20 and the connecting 
unit 22. Therefore, the lock device of the present embodiment is effective 
in providing reliability when the insertion opening 13 of the frame main 
part 12 is completely closed by the access door 18. 
When the video tape recorder 1 is used with the lock device of the present 
embodiment over an extended period of time, the relative position of the 
connecting portions 52a and 52b of the connecting unit 22 to the fixed 
portions 54a and 54b of the frame main part 12 is likely to deviate from 
the original position due to vibrations or deformations experienced by the 
video tape recorder 1. If the relative position of the connecting unit 22 
and the frame main part 12 deviates, the lock device of the present 
embodiment in such a condition is effective in providing reliability when 
the insertion opening 13 of the frame main part 12 is completely closed by 
the access door 18. It is possible for the lock device of the present 
embodiment to ensure a sealing performance of the frame main part 12. 
Further, the present invention is not limited to the above-described 
embodiments, and variations and modifications may be made without 
departing from the scope of the present invention.