Patent Application
20080055694
Embodiments of a micro-mirror array device according to the present invention will be described below in detail by referring to the accompanying diagrams. However, the present invention is not restricted to these embodiments.
Moreover, same reference numerals are assigned to components which are same in each embodiment described below, and detailed description of such components may be omitted.
As shown in
On the other hand, on the driving circuit board 201, drive electrodes 202 for driving the micro-mirrors 101 by electrostatic force, wires (not shown in the diagram) for passing electricity to the drive electrodes 202 and the micro-mirror array 100A, and pads for connections (not shown in the diagram) are formed.
Moreover, the micro-mirror array 100A is electrically connected to the driving circuit board 201 by the bumps 103 in the connecting areas 110, and the structure is formed such that it is possible to apply a potential difference between the micro-mirrors 101 and the drive electrodes 202.
As the bump 103, solder bump formed of solder, a gold bump formed of a gold wire, and a stud bump can be used.
Accordingly, since the bumps 103 made of a metallic member are disposed, it is possible to connect electrically the micro-mirror array 100A. Moreover, since the bump 103 which is a metallic member is subjected to plastic deformation by external force, it is possible to deform the metallic member appropriately such that the frame area 120 is formed to be flat. Consequently, it is possible to achieve a micro-mirror array device having a high flatness of the frame area 120, in which it is possible to connect electrically to the micro-mirror array.
Moreover, since the connecting areas 110 are disposed separately, independent of the frame area 120 which holds the plurality of micro-mirrors 101, the hinges 104 does not have an effect of heat and stress when the micro-mirror array 100A is electrically connected to the driving circuit board 201 by the bumps 103.
Consequently, a specific hinge 104 does not have an effect of the connecting area 110. It is possible to achieve the micro-mirror array device 100 in which all the mirrors 101 have uniform driving characteristics.
Moreover, since the bumps 103 have electrical conductivity, it is possible to electrically connect the mirror array to a desired part, and to apply a desired electric potential. Therefore, it is possible to let the micro-mirror 101 to be deflectable by electrical driving force. Consequently, it is possible to achieve the micro-mirror array device 100 which can be driven.
By using a semiconductor substrate of a material such as Si for the frame area 120 and the driving circuit board 201, it is possible to form an array structure which is highly densified, and fine. It is needless to mention that it is possible to use various materials which fall within the scope of a concept of the present invention.
Furthermore, by forming the connecting areas 110 and the frame area 120 by the same material, but as separate areas, necessary functions are exhibited. However, it is also useful to select different materials intentionally, and to let to have even stronger effect.
According to the micro-mirror array device according to the first embodiment having the abovementioned structure, since the connecting areas 110 are disposed separately from the frame area 120, the elastic members (hinges) 104 does not have an effect of heat and mechanical stress from the connecting member such as the bumps 103.
In this manner, since the bumps are provided only in the connecting areas on the outer sides of the mirror array, as a distance between the bump and the hinge becomes longer, a range of transmission of heat and a thermal stress is restricted to the connecting areas when the bumps 103 are connected. In other words, since there is no mirror which is specifically close to the bump, there is no mirror having a substantial effect on characteristics of the hinge. Therefore, it is possible to prevent a substantial variation in the driving characteristics of each mirror.
In other words, the specific hinge 104 does not have an effect of the bump 103. It is possible to achieve a micro-mirror array device in which all the micro-mirrors have uniform driving characteristics.
Furthermore, in one-dimensional array, since the frame area 120 has a long and slender structure in a one-dimensional direction, an effect of the connecting member, such as the frame is susceptible to be deformed due to the effect, is particularly substantial. In the first embodiment, since the connecting areas 110 are provided on the outer sides of the frame area 120, the hinges 104 of the mirror 101 do not have an effect easily of the connecting member (bump). Therefore, even in one-dimensional array, the hinges 104 of all mirrors 101 can maintain almost uniform characteristics.
Next, a second embodiment of the present invention will be described below.
The second embodiment, shows an example in which bumps 103a and 103b are disposed as two connecting members, in the connecting areas 110 similar as described by referring to
In the second embodiment, as shown in
The connecting areas 110 are electrically and mechanically connected to the driving circuit board 201 by using the bumps 103a and 103b.
Each of the micro-mirrors 101 is structured to be driven independently by electrostatic force, by the drive electrode 202 on the driving circuit board 201.
Here, for example, a case in which the micro-mirror array 100A is curved in a longitudinal direction (direction of arrangement of the array) can also be taken into consideration. In this case, since a distance from the driving circuit board 201 differs for each micro-mirror 101, the electrostatic force differs, and there is a possibility that respective driving sensitivity changes.
As a result of this, there is a difference in a range in which it can be driven, and a resolution which drives, for each micro-mirror 101, and it may not be possible to achieve a uniform micro-mirror array.
Even in such a case, according to the micro-mirror array device according to the second embodiment, by arranging the plurality of bumps 103a and 103b in the direction of arrangement (direction of a row) of the micro-mirror array 100A, the micro-mirror array 100A can be supported such that a curvature of the micro-mirror array 100A is mechanically corrected. Therefore, it is possible to make constant the distance between the micro-mirror 101 and the drive electrode 202.
In the one-dimensional mirror array, the connecting areas 110 are disposed on outer sides of the direction of arrangement (direction of a row) of the array. In other words, since it is connected by both ends of a long and slender array, and an area near central portion is not constrained, the entire array is susceptible to bending. In the present invention, the plurality of bumps 103a and 103b (connecting members) made of metallic member are disposed in the direction of arrangement of the array. Therefore, it is possible to fix an inclination of the connecting areas 110 substantial parallel to the driving circuit board 201 at a plurality of points to which the metallic member is connected. According to this effect, it is possible to suppress the bending of the entire array. As a result, a gap between the mirror 101 and the electrode becomes uniform for the entire array, and not only the hinge characteristics, but also the driving force also becomes uniform. Consequently, it is possible to achieve a mirror array device in which, the driving characteristics are same for all the mirrors 101.
Next, a third embodiment of the present invention will be described below.
The third embodiment is an example applicable to a two-dimensional array. As shown in
Consequently, even in the third embodiment, it is possible to realize a micro-mirror array device in which all the mirrors have the uniform driving characteristics.
Next, a fourth embodiment of the present invention will be described below.
The fourth embodiment shows an example in which, a metallic member 103A and an adhesive 103B are used as the connecting member. Concretely, it is possible to use a stud bump of gold for example, as the metallic member 103A, and to use an epoxy-based adhesive for electrical mounting (NCP: Non Conductive Paste) for example, as the adhesive 103B.
In the fourth embodiment, since the connecting member is formed by the metallic material 103A and the adhesive 103B, it is possible to let electrical connections to function by electroconductivity of the metallic member 103A, and to let mechanical connections to function by the adhesive 103B.
Consequently, it is possible to achieve a micro-mirror array device having both a high conductivity and a strong connecting power, and which is highly durable.
Next, a fifth embodiment of the present invention will be described below.
In the fifth embodiment, for example, an upper row 100A1 of the micro-mirror array in
In other words, in the fifth embodiment, it is possible to further improve a reliability of the system, in addition to show an action and effect similar as in the first embodiment described above.
In this manner, even when a plurality of rows of one-dimensional array is disposed, since the bump 103 is disposed only in the connecting area 110, the hinge 104 of the mirror 101 does not have an effect of the bump 103. Consequently, it is possible to achieve a micro-mirror array device having a plurality of one-dimensional arrays, with all uniform characteristics. As it has been mentioned above, since each of the one-dimensional arrays has main applications and a back-up at the time of break-down, or can be used for other application, it is possible to achieve a micro-mirror array having a plurality of functions.
Next, a sixth embodiment of the present invention will be described below.
As shown in
The hinges 704 are supported by beams 140 which are connected to the frame 102. In other words, the micro-mirrors 101 are supported integrally by the frame 102 to form the micro-mirror array.
On the other hand, on left and right sides of the frame area 120 similar as described by referring to
As in the sixth embodiment, in the micro-mirror array device 700 provided with the micro-mirrors 101 which are deflected around an axis parallel to the direction of arrangement of the micro-mirror array 700A, when the long frame area is distorted to be curved, it has various inclinations around an axis orthogonal to the axis around which the micro-mirrors 101 are deflected. However, since it is not possible to be deflected around the axis orthogonal to the axis around which the micro-mirrors 101 are deflected, it is not possible to correct the inclination.
In the sixth embodiment, since the connecting member 103 is structured such that the plurality of bumps 103a and 103b are disposed by arranging in the direction of arrangement of the micro-mirrors 101, it is possible to suppress the curve of the frame area 120 to be the minimum.
Consequently, it is possible to achieve a micro-mirror array device which cannot have an undesirable inclination in a direction in which the mirror can not be deflected.
It is possible to structure the connecting member only by bumps, or by the metallic member and the adhesive described in the fourth embodiment. However, in the micro-mirror array device 700 provided with the micro-mirrors 101 which are deflected around the axis parallel to the direction of arrangement of the micro-mirror array 700A in the sixth embodiment, by forming the connecting member 103 by the bumps 103a and 103b, it is possible to make an action and effect even more remarkable.
Moreover, it is also possible to form a plurality of rows of the one-dimensional arrays 700A in the frame area 120.
Next, a seventh embodiment of the present invention will be described below.
In the seventh embodiment, as shown in
As it has been described above, the entire structure in which, an arrangement is made such that the frame area 120 and the micro-mirror 101 are not let to have the effect of the connection by the connecting member in the connecting area 110, by providing the connecting area 110 around the frame area 120 adjacently, is in accordance with a basic concept of the present invention, and it is possible to make various modifications in this structure.
As it has been described above, the micro-mirror array device according to the present invention is useful as a micro-mirror array device in which a high optical quality is sought, and is suitable as a micro-mirror array device used in a WSS.
According to the present invention, it is possible to reduce an effect on a specific elastic member (hinge) due to a connecting member, and to realize a mirror array of almost uniform characteristics, and to provide a micro-mirror array device in which a variation in the driving-sensitivity characteristics of mirrors in the mirror array is suppressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP 2006-235478 | Aug 2006 | JP | national |
