This application is based upon and claims the benefit of priority from Japanese patent application No. 2021-093575, filed on Jun. 3, 2021, the disclosure of which is incorporated herein in its entirety by reference.
The present disclosure relates to a board-to-board connector.
As shown in
The receptacle fixing plate 102 includes a fixing leg 104 and a receptacle contact part 105. In the receptacle contact part 105, a contact piece 106A and a contact piece 106B are formed by cutting and bending.
In the case where a hold-down is provided with an elastic piece having a contact part, there is a possibility that elastic displacement of the contact part is hindered by the housing. Further, it is necessary to prevent curling deformation of an elastic piece.
An object of the present disclosure is to provide a technique to achieve a structure in which a contact part of an elastic piece provided in a hold-down is easily elastically displaceable and prevent curling deformation of the elastic piece.
According to an aspect of the present invention, there is provided a board-to-board connector to be mounted on a first board and interposed between the first board and a second board to electrically connect a plurality of pads of the first board to a plurality of pads of the second board, including a flat-plate housing; a plurality of contacts held on the housing; and a hold-down made of metal, wherein the housing includes a housing lower surface to be opposed to the first board when the board-to-board connector is mounted on the first board and a housing upper surface being an opposite of the housing lower surface, a hold-down accommodation recess is formed on the housing upper surface, the hold-down includes a flat-plate reinforcing plate part to be accommodated in the hold-down accommodation recess and cover an inner bottom surface of the hold-down accommodation recess; a solder leg projecting downward from the reinforcing plate part; and a hold-down elastic piece supported like a cantilever beam by the reinforcing plate part, the hold-down elastic piece includes, sequentially from a base to an end of the hold-down elastic piece, an elastic piece body; a contact part projecting upward beyond the housing upper surface; and a displacement restriction part to restrict upward displacement of the contact part, and the housing is formed in such a way that the contact part does not come into contact with the housing when the contact part is displaced downward and no longer projects upward beyond the housing upper surface.
The present disclosure achieves a structure in which a contact part of an elastic piece provided in a hold-down is easily elastically displaceable and prevents curling deformation of the elastic piece.
The above and other objects, features and advantages of the present disclosure will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present disclosure.
A first embodiment is described hereinafter with reference to
The CPU board 2 and the input/output board 4 are rigid boards such as a paper phenolic board or a glass epoxy board, for example.
The plurality of signal pad rows 6 extend parallel to one another. Each of the signal pad rows 6 includes a plurality of signal pads 10. The longitudinal direction of each signal pad row 6 is referred to as a pitch direction. Further, the direction orthogonal to the pitch direction is defined as a width direction. The plurality of signal pad rows 6 are arranged in the width direction. The thickness direction of the CPU board 2 is orthogonal to the pitch direction and the width direction, and it is referred to hereinafter as a vertical direction. The vertical direction includes downward which the connector opposed surface 2A faces, and upward opposite to downward. Note that the vertical direction, the upward direction, and the downward direction are directions used by way of illustration only and should not be interpreted as limiting the posture of the information processing device 1 and the connector 3 when they are actually used.
The plurality of bolt fastening holes 8 are disposed separately from each other in the pitch direction. The plurality of bolt fastening holes 8 include a first bolt fastening hole 8A, a second bolt fastening hole 8B, and a third bolt fastening hole 8C. The first bolt fastening hole 8A, the second bolt fastening hole 8B, and the third bolt fastening hole 8C are arranged in this recited order.
The plurality of positioning holes 9 include a first positioning hole 9P and a second positioning hole 9Q. The first positioning hole 9P and the second positioning hole 9Q are disposed separately from each other in the width direction. The first positioning hole 9P and the second positioning hole 9Q are disposed in such a way that the first bolt fastening hole 8A is interposed therebetween in the width direction.
The plurality of power supply pads 7 include a high voltage side electrode pad 7P, a high voltage side electrode pad 7Q, a low voltage side electrode pad 7R, and a low voltage side electrode pad 7S. Any of the plurality of power supply pads 7 may serve as a high voltage side or a low voltage side.
The high voltage side electrode pad 7P and the high voltage side electrode pad 7Q are disposed separately from each other in the width direction. The high voltage side electrode pad 7P and the high voltage side electrode pad 7Q are disposed in such a way that the first bolt fastening hole 8A is interposed therebetween in the width direction. The high voltage side electrode pad 7P is disposed between the first bolt fastening hole 8A and the first positioning hole 9P in the width direction. The high voltage side electrode pad 7Q is disposed between the first bolt fastening hole 8A and the second positioning hole 9Q in the width direction. Note that, however, the pattern shapes and positions of the high voltage side electrode pad 7P and the high voltage side electrode pad 7Q are arbitrary, and the high voltage side electrode pad 7P and the high voltage side electrode pad 7Q may be formed in a ring to surround the first positioning hole 9P and the second positioning hole 9Q, respectively.
The low voltage side electrode pad 7R and the low voltage side electrode pad 7S are disposed separately from each other in the width direction. The low voltage side electrode pad 7R and the low voltage side electrode pad 7S are disposed in such a way that the third bolt fastening hole 8C is interposed therebetween in the width direction. Note that, however, the pattern shapes and positions of the low voltage side electrode pad 7R and the low voltage side electrode pad 7S are arbitrary.
Referring back to
The plurality of signal pad rows 11 extend parallel to one another. The plurality of signal pad rows 11 are arranged in the width direction. Each of the signal pad rows 11 includes a plurality of signal pads 15.
The plurality of bolt fastening holes 13 are disposed separately from each other in the pitch direction. The plurality of bolt fastening holes 13 include a first bolt fastening hole 13A, a second bolt fastening hole 13B, and a third bolt fastening hole 13C. The first bolt fastening hole 13A, the second bolt fastening hole 13B, and the third bolt fastening hole 13C are arranged in this recited order.
The plurality of positioning holes 14 include a first positioning hole 14P and a second positioning hole 14Q. The first positioning hole 14P and the second positioning hole 14Q are disposed separately from each other in the width direction. The first positioning hole 14P and the second positioning hole 14Q are disposed in such a way that the first bolt fastening hole 13A is interposed therebetween in the width direction.
The plurality of power supply pads 12 include a pair of high voltage side electrode pads 12P, a pair of high voltage side electrode pads 12Q, a pair of low voltage side electrode pads 12R, and a pair of low voltage side electrode pads 12S.
The pair of high voltage side electrode pads 12P are disposed in such a way that one of them is adjacent to the first positioning hole 14P in the pitch direction, and the other one is adjacent to the first positioning hole 14P in the width direction. The pair of high voltage side electrode pads 12Q are disposed in such a way that one of them is adjacent to the second positioning hole 14Q in the pitch direction, and the other one is adjacent to the second positioning hole 14Q in the width direction. The pair of low voltage side electrode pads 12R and the pair of low voltage side electrode pads 12S are disposed in such a way that the third bolt fastening hole 13C is interposed therebetween in the width direction. Thus, the pair of low voltage side electrode pads 12R, the third bolt fastening hole 13C, and the pair of low voltage side electrode pads 12S are disposed in this recited order in the width direction.
The support board 5 is typically a part of a casing that accommodates the CPU board 2, the connector 3, and the input/output board 4, and it is made of aluminum or aluminum alloy, for example. The support board 5 includes a flat-plate board main body 20, a plurality of nuts 21, and a plurality of cylindrical positioning pins 22. The plurality of nuts 21 and the plurality of positioning pins 22 project upward from the board main body 20.
The plurality of nuts 21 include a first nut 21A, a second nut 21B, and a third nut 21C. The first nut 21A, the second nut 21B, and the third nut 21C are disposed to correspond to the first bolt fastening hole 13A, the second bolt fastening hole 13B, and the third bolt fastening hole 13C of the input/output board 4, respectively.
The plurality of positioning pins 22 include a first positioning pin 22P and a second positioning pin 22Q. The first positioning pin 22P and the second positioning pin 22Q are disposed to correspond to the first positioning hole 14P and the second positioning hole 14Q of the input/output board 4, respectively.
The connector 3 is mountable on the connector opposed surface 4A of the input/output board 4.
The plurality of contact rows 31 extend parallel to one another. The plurality of contact rows 31 are arranged in the width direction. The plurality of contact rows 31 extend in the pitch direction. Each contact row 31 includes a plurality of contacts 33 made of metal. Each contact 33 is formed by punching and bending a metal plate formed by plating copper or copper alloy, for example.
The plurality of hold-downs 32 include a high voltage side hold-down 32P, a high voltage side hold-down 32Q, a low voltage side hold-down 32R, and a low voltage side hold-down 32S. As shown in
Referring back to
First, the connector 3 is mounted on the input/output board 4. To be specific, the plurality of contact rows 31 are respectively soldered to the plurality of corresponding signal pad rows 11, and further the plurality of hold-downs 32 are respectively soldered to the plurality of corresponding power supply pads 12.
Next, the input/output board 4 on which the connector 3 is mounted is attached to the support board 5. At this time, the first nut 21A, the second nut 21B, and the third nut 21C of the support board 5 penetrate the first bolt fastening hole 13A, the second bolt fastening hole 13B, and the third bolt fastening hole 13C of the input/output board 4, respectively. Likewise, the first positioning pin 22P penetrates the first positioning hole 14P of the input/output board 4 and the first positioning hole 34P of the connector 3 in this recited order, and the second positioning pin 22Q penetrates the second positioning hole 14Q of the input/output board 4 and the second positioning hole 34Q of the connector 3 in this recited order.
Then, the CPU board 2 is attached to the support board 5 in such a way that the CPU board 2 overlaps the connector 3. At this time, the first positioning pin 22P and the second positioning pin 22Q penetrate the first positioning hole 9P and the second positioning hole 9Q of the CPU board 2, respectively. In this state, a first bolt 40A is fastened to the first nut 21A through the first bolt fastening hole 8A and the first bolt fastening hole 13A, a second bolt 40B is fastened to the second nut 21B through the second bolt fastening hole 8B and the second bolt fastening hole 13B, and a third bolt 40C is fastened to the third nut 21C through the third bolt fastening hole 8C and the third bolt fastening hole 13C. In this manner, the connector 3 is interposed between the CPU board 2 and the input/output board 4, and thereby the plurality of signal pads 15 of the input/output board 4 and the plurality of signal pads 10 of the CPU board 2 shown in
Further, the first positioning pin 22P is inserted into the first positioning hole 34P of the connector 3 and the first positioning hole 9P of the CPU board 2, and the second positioning pin 22Q is inserted into the second positioning hole 34Q of the connector 3 and the second positioning hole 9Q of the CPU board 2, and thereby highly accurate positioning of the CPU board 2 with respect to the connector 3 is achieved.
The connector 3 is described hereinafter in further detail.
As shown in
The housing 30 further includes a first corner part 60P, a second corner part 60Q, a third corner part 60R, and a fourth corner part 60S. The first corner part 60P is a corner at which the first pitch side surface 50 and the first width side surface 52 intersect. The second corner part 60Q is a corner at which the first pitch side surface 50 and the second width side surface 53 intersect. The third corner part 60R is a corner at which the second pitch side surface 51 and the first width side surface 52 intersect. The fourth corner part 60S is a corner at which the second pitch side surface 51 and the second width side surface 53 intersect. Thus, the first corner part 60P and the fourth corner part 60S are located at diagonal positions of the rectangular housing 30 when viewed from above. Likewise, the second corner part 60Q and the third corner part 60R are located at diagonal positions of the rectangular housing 30 when viewed from above. The above-described first positioning hole 34P is formed at the first corner part 60P. The second positioning hole 34Q is formed at the second corner part 60Q. The housing 30 has only two positioning holes, i.e., the first positioning hole 34P and the second positioning hole 34Q, as positioning holes to be used for positioning of the CPU board 2 with respect to the connector 3.
On the first pitch side surface 50, a press-fit groove 61P, a nut notch 50V, and a press-fit groove 61Q are formed in this recited order from the first width side surface 52 to the second width side surface 53.
On the second pitch side surface 51, a press-fit groove 61R, a nut notch 51V, and a press-fit groove 61S are formed in this recited order from the first width side surface 52 to the second width side surface 53.
On the CPU board opposed surface 30A, a hold-down accommodation recess 62P, a hold-down accommodation recess 62Q, a hold-down accommodation recess 62R, and a hold-down accommodation recess 62S are formed.
On the housing 30, a plurality of contact accommodation parts 63 and a nut penetrating hole 64 are further formed.
As shown in
The nut notch 50V is a notch for avoiding the physical interference between the first nut 21A shown in
Referring back to
The hold-down accommodation recess 62P includes an inner bottom surface 62P1. The hold-down accommodation recess 62P is formed to surround the first positioning hole 34P. Thus, the first positioning hole 34P is formed on the inner bottom surface 62P1 of the hold-down accommodation recess 62P. The inner bottom surface 62P1 of the hold-down accommodation recess 62P further has an insertion hole 62P2 that penetrates it in the vertical direction. The insertion hole 62P2 is formed apart from the first positioning hole 34P in the width direction.
The hold-down accommodation recess 62Q includes an inner bottom surface 62Q1. The hold-down accommodation recess 62Q is formed to surround the second positioning hole 34Q. Thus, the second positioning hole 34Q is formed on the inner bottom surface 62Q1 of the hold-down accommodation recess 62Q. The inner bottom surface 62Q1 of the hold-down accommodation recess 62Q further has an insertion hole 62Q2 that penetrates it in the vertical direction. The insertion hole 62Q2 is formed apart from the second positioning hole 34Q in the width direction.
The inner bottom surface 62P1 of the hold-down accommodation recess 62P and the inner bottom surface 62Q1 of the hold-down accommodation recess 62Q are planes that are parallel to the CPU board opposed surface 30A and located lower than the CPU board opposed surface 30A.
Each of the contact accommodation parts 63 is a part that accommodates each of the contacts 33. Each of the contact accommodation parts 63 is formed to penetrate the housing 30 in the vertical direction.
Likewise, the press-fit groove 61R and the like are formed on the second pitch side surface 51. Thus, the second pitch side surface 51 exists in a discontinuous manner in the width direction. For the following description, a part of the second pitch side surface 51 which is missing due to the formation of the press-fit groove 61R or the like is indicated by a chain double-dashed line, and the second pitch side surface 51 is specified by drawing a leader line of the second pitch side surface 51 from this chain double-dashed line.
As shown in
The first positioning hole 34P, the second positioning hole 34Q, the high voltage side hold-down 32P, the high voltage side hold-down 32Q, the low voltage side hold-down 32R, and the low voltage side hold-down 32S are hereinafter described in further detail with reference to
As shown in
The high voltage side hold-down 32P includes a reinforcing plate part 70, two solder legs 71, and a hold-down elastic piece 72.
The reinforcing plate part 70 is flat-plate shaped, and it is accommodated in the hold-down accommodation recess 62P and coverts the inner bottom surface 62P1 of the hold-down accommodation recess 62P. The reinforcing plate part 70 has a positioning penetrating hole 73 and an elastic piece insertion hole 74.
The reinforcing plate part 70 covers the inner bottom surface 62P1 of the hold-down accommodation recess 62P around the first positioning hole 34P. To be specific, the reinforcing plate part 70 is formed not to cover the inner edge 34PE of the first positioning hole 34P. Specifically, the inner edge 34PE of the first positioning hole 34P is located inside an inner edge 73A of the positioning penetrating hole 73 of the reinforcing plate part 70 when viewed from above. The reinforcing plate part 70 made of metal thereby does not hinder the positioning function of the inner edge 34PE of the first positioning hole 34P and the first positioning pin 22P. Further, the reinforcing plate part 70 made of metal reduces the amount of deformation when the first positioning hole 34P is deformed outward in the radial direction due to contact with the first positioning pin 22P, which avoids a significant decrease in positioning accuracy by the positioning function.
Each of the two solder legs 71 projects downward from the reinforcing plate part 70 toward the input/output board 4 and is soldered to the corresponding power supply pad 12 of the input/output board 4 shown in
The hold-down elastic piece 72 is supported like a cantilever beam by the reinforcing plate part 70. The hold-down elastic piece 72 is accommodated in the insertion hole 62P2 of the hold-down accommodation recess 62P. The hold-down elastic piece 72 is located below the reinforcing plate part 70. The details of the hold-down elastic piece 72 are described later.
As shown in
The high voltage side hold-down 32Q includes a reinforcing plate part 70, two solder legs 71, and a hold-down elastic piece 72, just like the high voltage side hold-down 32P.
The reinforcing plate part 70 is flat-plate shaped, and it is accommodated in the hold-down accommodation recess 62Q and coverts the inner bottom surface 62Q1 of the hold-down accommodation recess 62Q. The reinforcing plate part 70 has a positioning penetrating hole 73 and an elastic piece insertion hole 74.
The reinforcing plate part 70 is disposed to cover the inner bottom surface 62Q1 of the hold-down accommodation recess 62Q around the second positioning hole 34Q. To be specific, the reinforcing plate part 70 is formed not to cover the inner edge 34QE of the second positioning hole 34Q. Specifically, the inner edge 34QE of the second positioning hole 34Q is located inside an inner edge 73A of the positioning penetrating hole 73 of the reinforcing plate part 70 when viewed from above. The reinforcing plate part 70 made of metal thereby does not hinder the positioning function of the inner edge 34QE of the second positioning hole 34Q and the second positioning pin 22Q. Further, the reinforcing plate part 70 made of metal reduces the amount of deformation when the second positioning hole 34Q is deformed outward in the radial direction due to contact with the second positioning pin 22Q, which avoids a significant decrease in positioning accuracy by the positioning function.
Each of the two solder legs 71 projects downward from the reinforcing plate part 70 toward the input/output board 4 and is soldered to the corresponding power supply pad 12 of the input/output board 4 shown in
The hold-down elastic piece 72 is supported like a cantilever beam by the reinforcing plate part 70. The hold-down elastic piece 72 is accommodated in the insertion hole 62Q2 of the hold-down accommodation recess 62Q. The hold-down elastic piece 72 is located below the reinforcing plate part 70. The details of the hold-down elastic piece 72 are described later.
The low voltage side hold-down 32R and the low voltage side hold-down 32S shown in
The hold-down elastic piece 72 is described hereinafter in detail with reference to
As shown in
The elastic piece body 80 couples the contact part 81 to the reinforcing plate part 70 so as to allow elastic displacement of the contact part 81 in the vertical direction. The elastic piece body 80 extends from an end part 70A of the reinforcing plate part 70 in the pitch direction. The elastic piece body 80 extends from the end part 70A of the reinforcing plate part 70 in the pitch direction to come down into a lower space 70B of the reinforcing plate part 70. The elastic piece body 80 includes a curve part 80A and an extension part 80B sequentially from the end part 70A of the reinforcing plate part 70 to the contact part 81. The curve part 80A extends downward from the end part 70A of the reinforcing plate part 70 and also curved in a semicircular arc that is convex toward the pitch direction. The extension part 80B extends linearly in the pitch direction from the curve part 80A. The extension part 80B may extend parallel to the pitch direction or may be slightly tilted from the pitch direction. The extension part 80B extends in the lower space 70B of the reinforcing plate part 70 indicated by a chain double-dashed line.
The contact part 81 is a part that comes into contact with the power supply pad 7 of the connector opposed surface 2A of the CPU board 2 shown in
The displacement restriction part 82 restricts upward elastic displacement of the contact part 81. In this embodiment, the displacement restriction part 82 restricts upward displacement of the contact part 81 that exceeds a predetermined value of displacement. As shown in
When the CPU board 2 is pressed against the connector 3, the contact part 81 comes into contact with the corresponding power supply pad 7 of the connector opposed surface 2A of the CPU board 2 shown in
As a result that the contact part 81 is elastically displaced downward, the contact part 81 no longer projects upward beyond the CPU board opposed surface 30A, and thereby the contact part 81 does not come into contact with the housing 30. This is because the hold-down accommodation recess 62Q has the insertion hole 62Q2, and the hold-down elastic piece 72 is accommodated in the insertion hole 62Q2 as shown in
Although the displacement restriction part 82 includes the pair of projecting parts 83, one of the pair of projecting parts 83 may be omitted. Further, although the pair of projecting parts 83 project in the width direction from the contact part 81, the pair of projecting parts 83 may project in the pitch direction from the contact part 81.
Further, the pair of projecting parts 83 that constitute the displacement restriction part 82 may be not opposed to the lower surface 70C of the reinforcing plate part 70 in the vertical direction when no load is imposed on the hold-down elastic piece 72. Specifically, the displacement restriction part 82 may be opposed to the lower surface 70C of the reinforcing plate part 70 in the vertical direction only after the contact part 81 is drawn upward.
Further, the pair of projecting parts 83 that constitute the displacement restriction part 82 may be already in contact with the lower surface 70C of the reinforcing plate part 70 before assembly of the information processing device 1.
Each of the contacts 33 and each of the contact accommodation parts 63 are described hereinafter with reference to
As shown in
The press-fitting space 301 is formed as a penetrating hole that penetrates the housing 30 in the vertical direction. Specifically, the press-fitting space 301 is open to the CPU board opposed surface 30A and the input/output board opposed surface 30B. The housing 30 includes, for each press-fitting space 301, two pitch partition surfaces 304 that partition the press-fitting space 301 in the pitch direction.
Referring back to
The separating wall 303 is a wall that spatially separates the press-fitting space 301 and the solder connection checking hole 302 as described above, and it is formed between the press-fitting space 301 and the solder connection checking hole 302. As shown in
The press-fit part 320 is a part to be press-fit into the press-fitting space 301 shown in
The soldering part 321 is a part to be soldered to the corresponding signal pad 15 of the input/output board 4 shown in
The electrical contact spring piece 322 is a part that functions as an electrical contact point of the CPU board 2 shown in
The spring piece joining part 325 extends downward from the upper end of the press-fit part 320.
The easily elastically deformable part 326 extends from the lower end of the spring piece joining part 325 and is formed in a U-shape that is convex in the width direction. Specifically, the easily elastically deformable part 326 includes a lower straight part 326A, a curve part 326B, and an upper straight part 326C. The lower straight part 326A, the curve part 326B, and the upper straight part 326C are continuously formed in this recited order. The lower straight part 326A and the upper straight part 326C are opposed to each other in the vertical direction. The lower straight part 326A and the upper straight part 326C are joined through the curve part 326B.
The contact part 327 is a part that can come into electrical contact with the corresponding signal pad 10 of the CPU board 2 shown in
Referring back to
In this embodiment, the separating wall 303 that separates the press-fitting space 301 and the solder connection checking hole 302 is formed as described above. The presence of the separating wall 303 prevents shavings of the housing 30, which can be generated when press-fitting the press-fit part 320 into the press-fitting space 301, from moving into the solder connection checking hole 302. This allows checking the solder fillet 330 from above through the solder connection checking hole 302 with no problem.
The first embodiment is described above, and the above-described embodiment has the following features.
As shown in
The displacement restriction part 82 restricts upward displacement of the contact part 81 that exceeds a predetermined value of displacement. In this structure, no load is imposed on the hold-down elastic piece 72 before use of the connector 3.
The displacement restriction part 82 restricts upward displacement of the contact part 81 by coming into contact with the reinforcing plate part 70. In this structure, the displacement restriction part 82 restricts upward displacement of the contact part 81 more reliably compared with the case of restricting upward displacement of the contact part 81 by coming into contact with the housing 30.
The displacement restriction part 82 restricts upward displacement of the contact part 81 by coming into contact with the lower surface 70C of the reinforcing plate part 70 shown in
The displacement restriction part 82 is opposed to the lower surface 70C of the reinforcing plate part 70 in the vertical direction. In this structure, the displacement restriction part 82 reliably comes into contact with the lower surface 70C of the reinforcing plate part 70 when the contact part 81 is displaced upward.
The displacement restriction part 82 includes the projecting part 83 that projects in the width direction, which is the direction orthogonal to the longitudinal direction of the contact part 81. The projecting part 83 is opposed to the lower surface 70C of the reinforcing plate part 70 in the vertical direction. In this structure, the displacement restriction part 82 more reliably comes into contact with the lower surface 70C of the reinforcing plate part 70 when the contact part 81 is displaced upward.
As shown in
As shown in
As shown in
As shown in
As shown in
Although the first embodiment is described above, the first embodiment can be modified as follows.
Although the connector 3 includes the four hold-downs 32, the connector 3 may include only two hold-downs 32 or one hold-down 32.
Although the connector 3 includes the plurality of contacts 33, the connector 3 may include only one contact 33.
A second embodiment is described hereinafter with reference to
In the above-described first embodiment, as shown in
In this embodiment, as shown in
A third embodiment is described hereinafter with reference to
In the above-described embodiment, as shown in
In this embodiment, as shown in
A fourth embodiment is described hereinafter with reference to
In the above-described first embodiment, as shown in
In this embodiment, as shown in
The first through forth embodiments can be combined as desirable by one of ordinary skill in the art.
From the disclosure thus described, it will be obvious that the embodiments of the disclosure may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure, and all such modifications as would be obvious to one skilled in the art are intended for inclusion within the scope of the following claims.
Number | Date | Country | Kind |
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2021-093575 | Jun 2021 | JP | national |