# Patent

## Title
Latch device requiring no movable operating member that is operated from the exterior

## Abstract

In order to latch an object member that is movable in a predetermined direction, a latch device has a heart cam that follows movement of the object member, and a latch member that is movable between a first position where it does not engage the object member and a second position where it engages the object member in the predetermined direction. A cam follower engaging the heart cam and the latch member urges the latch member toward one of the first and second positions following movement of the heart cam. However, actual movement of the latch member is controlled by a control mechanism that operates depending on the shape and the number of times of movement of the heart cam.

## Background
This application claims priority to prior Japanese patent application JP2004-222052, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
This invention relates to a latch device for latching an object member that is movable in a predetermined direction.
Recently, it has been proposed to use, as an object member that is loadable and unloadable into and from an information processing device, a module in the form of a case and a CD, CD-ROM, DVD, HD, or the like that is accommodated in the case (hereinafter referred to simply as a “module”). In order to enable the use of the module, the information processing device has a housing formed with an insertion hole. The module is inserted into the insertion hole depending on necessity. When the module is replaced with another or becomes unnecessary, it is removed from the insertion hole.
The information processing device is provided with a latch device that serves to lock the module in the state where it is inserted in the insertion hole. The latch device of this type normally has a release mechanism for releasing the module. The release mechanism has a movable operating member to be operated from the exterior and releases the module depending on an operation of the operating member. The released module can be easily removed from the information processing device.
However, since the conventional latch device requires the movable operating member to be operated from the exterior, the number of parts increases and the structure thereof is complicated.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a latch device that makes unnecessary a movable operating member to be operated from the exterior.
It is another object of the present invention to provide a latch device that enables not only an insert operation of an object member such as a module but also a remove operation thereof by pushing the object member.
It is still another object of the present invention to provide a small-size information processing device having a latch device of a simple structure for latching a module.
Other object of the present invention will become clear as the description proceeds.
According to an aspect of the present invention, there is provided a latch device for latching an object member that is movable in a predetermined direction, the latch device comprising a heart cam that follows movement of the object member, a latch member movable between a first position where the latch member does not engage the object member and a second position where the latch member engages the object member in the predetermined direction, a cam follower engaging the heart cam and the latch member to urge the latch member toward one of the first and second directions following movement of the heart cam, and a control mechanism that controls movement of the latch member depending on a shape and the number of times of movement of the heart cam.



BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic perspective view showing the overall appearance of an information processing device according to an embodiment of the present invention;
FIG. 2 is an explanatory diagram showing, on an enlarged scale, the main part of the information processing device of FIG. 1 along with a module;
FIG. 3A is a front view of a latch device used in the information processing device of FIG. 1;
FIG. 3B is a left-side view of the latch device shown in FIG. 3A;
FIG. 3C is a bottom view of the latch device shown in FIG. 3A;
FIG. 4 is a front view showing, on an enlarged scale, the latch device of FIGS. 3A to 3C in the state where a cover member is detached;
FIG. 5 is a front view of an assembly formed by a base member, a cam member, and a return spring which are included in the latch device of FIGS. 3A to 3C;
FIG. 6 is a bottom view of an assembly formed by a latch member and a rod spring which are included in the latch device of FIGS. 3A to 3C;
FIG. 7A is a front view of the base member included in the latch device of FIGS. 3A to 3C;
FIG. 7B is a plan view of the base member shown in FIG. 7A;
FIG. 8A is a front view of the cam member included in the latch device of FIGS. 3A to 3C;
FIG. 8B is a bottom view of the cam member shown in FIG. 8A;
FIG. 9A is a front view of the latch member included in the latch device of FIGS. 3A to 3C;
FIG. 9B is a left-side view of the latch member shown in FIG. 9A;
FIG. 10A is a front view of the rod spring included in the latch device of FIGS. 3A to 3C;
FIG. 10B is a bottom view of the rod spring shown in FIG. 10A;
FIG. 11 is an explanatory diagram for explaining operation of a heart cam formed on the cam member of FIGS. 8A and 8B;
FIG. 12A is a front view like FIG. 4, showing the state where the cam member has slightly slid;
FIG. 12B is a front view like FIG. 4, showing the state where the cam member has further slid but a latch operation is not obtained; and
FIG. 12C is a front view like FIG. 4, showing the state where the cam member has further slid and the latch operation is obtained.



DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, description will be given of an information processing device according to an embodiment of the present invention.
The illustrated information processing device is designated by a reference numeral 1 and is, for example, a laptop personal computer and comprises a body portion 2 and a cover portion 3 attached to the body portion 2 so as to be openable and closable. The cover portion 3 has a display 4. The body portion 2 is provided with an operating portion 5 such as a keyboard.
A housing of the body portion 2 is formed with an insertion hole 6 for enabling use of a module of a flat plate shape as an object member. The module is inserted into the insertion hole 6 depending on necessity. When the module is replaced with another or becomes unnecessary, it is removed from the insertion hole 6 and separated from the information processing device 1.
Referring also to FIG. 2, a module 7 is being inserted into the insertion hole 6. Inside the body portion 2, a passage 8 is formed so as to extend in a horizontal first direction (predetermined direction) A1 following the insertion hole 6. Therefore, the module 7 inserted into the insertion hole 6 is located in the passage 8. The module 7 has a projected portion 7a and a recessed portion 7b formed on a side surface thereof.
A latch device 10 is disposed on a lateral side of the passage 8 in a horizontal second direction A2 perpendicular to the first direction A1. The latch device 10 serves to latch the module 7 in the inserted state. The latch device 10 is firmly fixed to the housing of the body portion 2.
Referring also to FIGS. 3A to 12C, description will be given of a structure of the latch device 10.
In FIGS. 3A to 3C, the latch device 10 comprises a base member 11 and a cover member 12 coupled to the base member 11. The base member 11 is made of an insulating material or a metal material. The cover member 12 is formed by a metal plate and fixedly engaged with the base member 11.
As seen from FIG. 4 where the cover member 12 is detached, a cam member 13, a latch member 14, a rod spring 15, and a return spring 16 are disposed between the base member 11 and the cover member 12. The cam member 13 and the latch member 14 are each made of an insulating resin or a metal material. On the other hand, the rod spring 15 and the return spring 16 are each formed by a metal member having springiness. For convenience of illustration, the return spring 16 is exemplarily illustrated.
In FIG. 5, the base member 11 has guide rails 11a and 11b on an upper surface thereof. The cam member 13 is attached to the base member 11 so as to be slidable only in the first directions A1 along the guide rails 11a and 11b. The cam member 13 may be called a sliding member. The return spring 16 is a tension coil spring having opposite ends connected to the base member 11 and the cam member 13, respectively, and urges the cam member 13 toward the side of the insertion hole 6 in the first direction A1. Part of the cam member 13 protrudes into the passage 8 as an operating projection 13a. 
On an upper surface of the cam member 13 is formed a heart cam 17 in the form of a generally heart-shaped groove that is substantially parallel to a predetermined plane spreading in the first and second directions A1 and A2. A specific shape of the heart cam 17 will be described in detail later.
The base member 11 further has a recessed portion 11c and a projected portion 11d near the return spring 16. As shown in FIG. 4, the latch member 14 is mounted on the upper side of the cam member 13. In that event, an end portion 14a of the latch member 14 is disposed in the recessed portion 11c. Then, a shaft hole 14b of the latch member 14 is fittingly engaged with the projected portion 11d. The end portion 14a of the latch member 14 is made slightly smaller than the recessed portion 11c so that the latch member 14 is swingable about the projected portion 11d as a fulcrum along the predetermined plane only in a certain angle range.
The latch member 14 has an engaging portion 14c formed at the other end portion thereof, i.e. a free end thereof. The engaging portion 14c can protrude into the passage 8 from the base member 11 and the cover member 12 substantially in the second direction A2 depending on a swing angle of the latch member 14. In other words, the latch member 14 is movable between a first position where the engaging portion 14c does not engage the module 7 and a second position where the engaging portion 14c engages the module 7 in the first direction A1.
In FIGS. 4 and 6, the latch member 14 has a small hole 14d near the shaft hole 14b. The rod spring 15 has an intermediate portion 15a extending between the cam member 13 and the latch member 14, a first end portion 15b that is bent perpendicularly from one end of the intermediate portion 15a and inserted into the small hole 14d so as to engage the latch member 14 in its swing direction, and a second end portion 15c that is bent from the other end of the intermediate portion 15a in a third direction (direction perpendicular to the sheet surface in FIG. 4 or FIG. 6) perpendicular to the first and second directions A1 and A2 so as to engage the heart cam 17 shown in FIG. 5.
In FIGS. 4 to 6, when the module 7 is inserted into the passage 8, the projected portion 7a of the module 7 engages the operating projection 13a in the first direction A1 to thereby move the cam member 13 against the biasing force of the return spring 16. According to the movement of the cam member 13, the second end portion 15c of the rod spring 15 moves following the heart cam 17. That is, the second end portion 15c of the rod spring 15 is moved by the heart cam 17. Therefore, the rod spring 15 is herein also called a cam follower.
When the second end portion 15c is moved by the heart cam 17, the rod spring 15 urges the latch member 14 toward one of the first and second positions through the first end portion 15b. Specifically, when the cam member 13 starts moving, the rod spring 15 urges the latch member 14 toward the second position. However, actual movement of the latch member 14 is controlled by a control mechanism.
Details of the base member 11, the cam member 13, the latch member 14, and the rod spring 15 are shown in FIGS. 7A and 7B, FIGS. 8A and 8B, FIGS. 9A and 9B, and FIGS. 10A and 10B, respectively. The cam member 13 has a projected portion 13b formed on the upper surface thereof near the heart cam 17. On the other hand, on a lower surface of the latch member 14 is formed a projected wall 14e that engages the projected portion 13b. The latch member 14 is provided, near the free end thereof, with a lacking portion 14f where the projected wall 14e is not formed. Further, the latch member 14 is formed with a window portion 14g passing therethrough. A combination of the projected portion 13b, the projected wall 14e, the lacking portion 14f, the window portion 14g, and the heart cam 17 is referred to as the control mechanism.
Now, referring also to FIGS. 11 to 12C, description will be given of the operation of the latch device 10 and the operation of the control mechanism.
In FIG. 11, the heart cam 17 is hatched so as to be distinguished from other portions. When the module 7 is not inserted in the passage 8, the second end portion 15c of the rod spring 15 is located at a point a, i.e. a normal position, of the heart cam 17 and the latch member 14 is in the first position.
First, description will be given of a case where the module 7 is set in the information processing device 1. When an operator inserts the module 7 into the passage 8, the projected portion 7a of the module 7 engages the operating projection 13a of the cam member 13 in the first direction A1. When the module 7 is pushed, the cam member 13 moves. As a result, the second end portion 15c of the rod spring 15 moves along the heart cam 17 to reach a point b. During this movement, the rod spring 15 urges the latch member 14 toward the second position. However, since the projected portion 13b of the cam member 13 is in engagement with the projected wall 14e of the latch member 14, the latch member 14 is retained in the first position. Therefore, the rod spring 15 gradually increases elastic bending to store energy during the movement. Herein, a combination of the projected portion 13b and the projected wall 14e will be referred to as a first engaging mechanism.
At the groove bottom of the heat cam 17, there is formed, from the point b to a point c, a steep ramp 17a that gradually raises the second end portion 15c of the rod spring 15 following the sliding movement of the cam member 13. Further, from the point c to a point d of the heart cam 17, there is formed a large height difference 17b that rapidly lowers the second end portion 15c of the rod spring 15. In this manner, a protuberant portion is defined at part of the heart cam 17 by the steep ramp 17a and the large height difference 17b. 
When the cam member 13 is further moved by the module 7, the second end portion 15c of the rod spring 15 gets on the protuberant portion along the heart cam 17 to reach the point c. In this event, the intermediate portion 15a of the rod spring 15 is inserted into the window portion 14g of the latch member 14. Simultaneously with or immediately after this, the projected portion 13b and the projected wall 14e disengage from each other. That is, the projected portion 13b reaches a position confronting the lacking portion 14f. However, an edge of the window portion 14g of the latch member 14 is locked by the intermediate portion 15a of the rod spring 15 in this event, the latch member 14 continues to be retained at the first position or near that position. Therefore, the rod spring 15 maintains the large stored energy. Herein, the projected portion 13b and the edge of the window portion 14g cooperatively constitute an engaging portion or a second engaging mechanism. Further, a combination of the steep ramp 17a and the lacking portion 14f will be referred to as an engagement switching mechanism that switches from the first engaging mechanism to the second engaging mechanism following the movement of the heart cam 17.
When the cam member 13 is further moved by the module 7, the second end portion 15c of the rod spring 15 passes through the large height difference 17b of the heart cam 17 to reach the point d. The second end portion 15c is rapidly lowered upon passing through the large height difference 17b so that the intermediate portion 15a of the rod spring 15 disengages from the window portion 14g of the latch member 14. Then, the latch member 14 is completely released and therefore rapidly moves toward the second position by the stored energy of the rod spring 15. Herein, the large height difference 17b of the heart cam 17 serves as an engagement release mechanism that releases the operation of the foregoing second engaging mechanism.
As a result, the engaging portion 14c of the latch member 14 protrudes into the passage 8 and is inserted into the recessed portion 7b of the module 7. Therefore, the module 7 is disposed at a predetermined position of the information processing device 1 and locked by the latch member 14 so as to be prevented from detachment.
Upon the disengagement of the intermediate portion 15a of the rod spring 15 from the window portion 14g of the latch member 14, the second end portion 15c of the rod spring 15 is urged to move in a direction opposite to the latch member 14 by the stored energy of the rod spring 15. However, the movement thereof is restricted due to its collision with a wall portion of the cam member 13 at a point h of the heart cam 17.
When the module 7 is locked by the latch member 14, the insertion force of the module 7 may be released. When the insertion force of the module 7 is released, the cam member 13 is slightly returned by the return spring 16 so that the second end portion 15c of the rod spring 15 is stopped in the state where it is located at a point e. In addition, the projected portion 13b of the cam member 13 confronts the projected wall 14e of the latch member 14 in the second direction A2. Therefore, the latch member 14 is prevented from returning to the first position from the second position.
Now, description will be given of a case where the module 7 is removed from the information processing device 1. In this case, the operator slightly pushes the module 7. Then, the second end portion 15c of the rod spring 15 moves to a point f. In that event, the latch member 14 is pushed by the second end portion 15c of the rod spring 15 so as to be moved and returned to the first position. As a result, the projected portion 13b of the cam member 13 enters the lacking portion 14f of the latch member 14.
When the pushing force to the module 7 is released, the second end portion 15c of the rod spring 15 moves to a point g. From this point, the projected portion 13b of the cam member 13 engages the projected wall 14e to provide the state where the first engaging mechanism is operated. Thereafter, the cam member 13 is returned to the initial position by the return spring 16. Therefore, the module 7 is pushed out of the passage 8 by the operating projection 13a of the cam member 13. In this event, the second end portion 15c of the rod spring 15 is returned to the point a, i.e. the normal position.
In order to prevent backward movement of the second end portion 15c of the rod spring 15, the heart cam 17 is formed with low stepped portions 17c and 17d, a gentle ramp 17e, and so on at several portions.
The rod spring 15 also has a function as an elastic member to urge and move the latch member 14 in the direction crossing the slide direction (A1) of the cam member 13.
While the present invention has thus far been described in connection with a single embodiment thereof, it will readily be possible for those skilled in the art to put this invention into practice in various other manners. For example, it may be designed such that when the module 7 is inserted, an insertion end thereof, instead of the projected portion 7a thereof, engages the operating projection 13a of the cam member 13. Further, the latch member 14 may be formed with a non-through recessed portion instead of the through window portion 14g. Further, the generally heart-shaped groove forming the heart cam 17 may be inclined with respect to the foregoing predetermined plane. In addition, the present invention is applicable not only to an information processing device such as a computer, but also to various devices or apparatuses each required to latch a movable object member.

## Claims

1. A latch device for latching a member that is movable in a predetermined direction, said latch device comprising:
a base member;
a latch member mounted on said base member and having an engaging portion for engaging with said member in said predetermined direction, said latch member being swingable about a fulcrum at one end thereof in a predetermined plane between a first position where said engaging portion engages said member in said predetermined direction;
a cam member disposed between said latch member and said base member and attached to said base member so as to be slidable in said predetermined direction, said cam member having a heart cam and an operating projection which is operated by said member to make said cam member follow movement of said member in said predetermined direction;
a cam follower engaging said heart cam and said latch member to urge said latch member toward one of said first and second positions following movement of said heart cam, said cam follower comprising a rod spring having a first end portion locked by said latch member and a second end portion locked by said heart cam; and
a control mechanism that controls movement of said latch member depending on a shape and the number of times of movement of said heart cam, said control mechanism comprising a latch locking mechanism for forcibly locking said latch member at said first position and a latch release mechanism for releasing operation of said latch locking mechanism depending on the movement of said heart cam.

2. The latch device according to claim 1, wherein said rod spring comprises:
an intermediate portion extending in said predetermined direction;
a first end portion located at one end of said intermediate portion and engaging said latch member; and
a second end portion that is bent perpendicularly from the other end of said intermediate portion so as to engage said heart cam.

3. The latch device according to claim 2, wherein said control mechanism comprises:
a first engaging mechanism coupled to said cam member and said latch member for retaining said latch member at said first position by engagement between said latch member and said cam member;
a second engaging mechanism coupled to said latch member and said intermediate portion for retaining said latch member at said first position by engagement between said latch member and said intermediate portion;
an engagement switching mechanism coupled to said first and said second engaging mechanisms and said hear cam for switching from said first engaging mechanism to said second engaging mechanism following the movement of said heart cam; and
an engagement release mechanism coupled to said engaging mechanism and said heart cam for releasing operation of said engaging mechanism following the movement of said heart cam.

4. The latch device according to claim 2, wherein said heart cam has a generally heart-shaped groove formed on said cam member, said generally heart-shaped groove has a protuberant portion defined by a ramp that gradually raises said second end portion following sliding movement of said cam member and by a step that rapidly lowers said second end portion, and said latch member has an engaging portion that engages said intermediate portion when said second end portion is placed on said protuberant portion, to thereby retain said latch member at said first position.

5. The latch device according to claim 1 further comprising a cover member coupled to said base member, wherein said cam member, said latch member, said rod spring, and said return spring are disposed between said base member and said cover member.

6. An information processing device comprising:
a housing defining therein a passage that enables insertion and removal of a module; and
the latch device according to claim 1 which is disposed adjacent to said passage and fixed to said housing.

7. An information processing device comprising:
a housing defining therein a passage that enables insertion and removal of a member in a predetermined direction; and
a latch device assembled as a unit separated from said housing and disposed adjacent to said passage, wherein said latch device comprises:
a base member fixed to said housing;
a latch member mounted on said base member and having an engaging portion for engaging with said member in said predetermined direction, said latch member being movable between a first position where said engaging portion protruded in said passage and a second position where said engaging portion retracted from said passage;
a cam mechanism coupled to said latch member and base member, and having an operating projection which project into said passage and is movable in said predetermined direction following said object member;
a control mechanism coupled to said latch member and said cam mechanism for controlling movement of said latch member in response to movement of said operating projection; and
a cover coupled to said base member to cover said latch member, said cam mechanism, and said control mechanism.