Patent Publication Number: US-9849398-B2

Title: Toy block

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention is ideally applied to a toy block enabling the creation of various shapes by assembling multiple blocks. 
     Description of the Related Art 
     As illustrated in  FIG. 1 , a toy block, which consists of a base section C 3  having a parallelepiped shape with a hollow bottom and a cylindrical projection C 2  projecting in a cylindrical shape from the base section C 3 , and in which assembly is enabled by interlocking the cylindrical projection C 2  into the hollow portion of the base section C 3 , is conventionally known (see PTL 1, for example). 
     With this toy block, the creation of various shapes is enabled by suitably combining blocks with different numbers of cylindrical projections, and building up blocks from the bottom upwards. 
     PATENT LITERATURE 
     Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. H10-506309 
     SUMMARY OF THE INVENTION 
     With blocks of such a configuration ( FIGS. 1(A) and 1(B) ), there are limits on the shapes that can be formed, since blocks can only be extended in the vertical direction. Also, in the case of wanting to form a complex shape, there has been a problem in that the order of assembly and combinations of blocks must be carefully considered, and there is little freedom of assembly. 
     Being devised in consideration of the above points, the present invention provides a toy block that may improve the freedom of assembly. 
     Solution to Problem 
     In order to solve such problems, a toy block of the present invention is configured to include: a base section configured such that, taking the unit edge length to be 1 and a cube expressed as 1×1×1 to be one unit size, the base section has a parallelepiped shape of size approximately equal to one or more conjoined unit sizes, and is composed of an open, hollow face taken to be the bottom, four lateral walls, and a roof; and cylindrical projections of cylindrical shape provided on the outer face of one or more of the roof and the lateral walls, with a diameter being equal to or greater than 0.4 but less than 0.6 with respect to the unit edge length, and a height being (1−diameter)×(0.4 to 0.5 inclusive); wherein the base section has an interlocking section that is enclosed by the four lateral walls, and by contacting and interlocking with other cylindrical projections of identical shape to the cylindrical projections with respect to at least one of the lateral walls, holds the other cylindrical projections; and the wall thickness near the bottom of the lateral walls is expressed as approximately (1−diameter)×0.5+alpha, where alpha is between −0.05 and 0.03 inclusive. 
     Thus, in the toy block, even in the case where cylindrical projections project in the horizontal direction, cylindrical projections projecting in the vertical direction and the horizontal direction do not collide with each other, and additionally, cylindrical projections projecting in the horizontal direction are able to firmly hold other blocks. 
     Advantageous Effects of Invention 
     According to the present invention, in the toy block, even in the case where cylindrical projections project in the horizontal direction, cylindrical projections projecting in the vertical direction and the horizontal direction do not collide with each other, and additionally, cylindrical projections projecting in the horizontal direction are able to firmly hold other blocks. In this way, the present invention is able to realize a toy block that may improve the freedom of assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram illustrating a configuration of a conventional 1-unit block. (A) is a side view, (B) is a top view, (C) is an illustration of a 1-unit block with a lateral wall projection, (D) is an illustration of a 1-unit block with a lateral wall, and (E) is an illustration of the assembly of a 1-unit block with a lateral wall. 
         FIG. 2  is a schematic diagram illustrating a configuration of a 1-unit block according to the first embodiment. (A) is a perspective view, (B) is a top view, (C) is a side view, (D) is a cross-section view, and (E) is a bottom view. 
         FIG. 3  is a schematic diagram illustrating a configuration of a 1-unit block with a lateral wall projection according to the first embodiment. (A) is a perspective view and (B) is a top view. 
         FIG. 4  is a schematic diagram accompanying a description of the assembly of 1-unit blocks according to the first embodiment. (A) is an illustration of the assembly of a 1-unit block with a lateral wall projection, (B) is an illustration of the assembly of a 1-unit block with a lateral wall hole, and (C) is an illustration of various assembly. 
         FIG. 5  is a schematic diagram illustrating a configuration of a 1-unit block with a lateral wall hole according to the first embodiment. (A) is a perspective view and (B) is a top view. 
         FIG. 6  is a schematic diagram illustrating a configuration of a 2-unit block according to the first embodiment. (A) is a perspective view, (B) is a top view, (C) is a side view ( 1 ), (D) is a side view ( 2 ), and (E) is a bottom view. 
         FIG. 7  is a schematic diagram illustrating a configuration ( 1 ) of a 2-unit block with a lateral wall projection according to the first embodiment. (A) is a perspective view and (B) is a top view. 
         FIG. 8  is a schematic diagram illustrating a configuration ( 2 ) of the 2-unit block with a lateral wall projection according to the first embodiment. (A) is a perspective view and (B) is a top view. 
         FIG. 9  is a schematic diagram illustrating a configuration ( 1 ) of an 8-unit block according to the first embodiment. (A) is a perspective view, (B) is a top view, (C) is a side view, (D) is a front view, and (E) is a bottom view. 
         FIG. 10  is a schematic diagram illustrating a configuration ( 2 ) of the 8-unit block according to the first embodiment. (A) is a bottom view, (B) is a cross-section view along A-A′, (C) is a cross-section view along B-B′, and (D) is a diagram illustrating how interlocking occurs. 
         FIG. 11  is a schematic diagram illustrating a configuration of a 4-unit block according to the first embodiment. (A) is a perspective view, (B) is a top view, (C) is a side view, (D) is a front view, and (E) is a bottom view. 
         FIG. 12  is a schematic diagram illustrating configurations of blocks with lateral wall projections according to the first embodiment. (A) is a perspective view of an 8-unit block with lateral wall projections, (B) is a top view of the 8-unit block with lateral wall projections, (C) is a perspective view of a 4-unit block with lateral wall projections, and (D) is a top view of the 4-unit block with lateral wall projections. 
         FIG. 13  is a schematic diagram illustrating a configuration of an 8-unit block with lateral wall holes according to the first embodiment. (A) is a perspective view, (B) is a side view, and (C) is a top view illustrating the lateral wall holes. 
         FIG. 14  is a schematic diagram illustrating a configuration of a 4-unit block with lateral wall holes according to the first embodiment. (A) is a perspective view and (B) is a top view. 
         FIG. 15  is a schematic diagram illustrating a configuration of a 16-unit block according to the first embodiment. (A) is a top view, (B) is a bottom view ( 1 ), (C) is a bottom view ( 2 ), and (D) is a bottom view ( 3 ). 
         FIG. 16  is a schematic diagram illustrating a configuration ( 1 ) of an 8-unit block according to the second embodiment. (A) is a bottom view, (B) is a cross-section view along A-A′, and (C) is an enlarged cross-section view of the lateral wall bottom. 
         FIG. 17  is a schematic diagram illustrating a configuration ( 2 ) of the 8-unit block according to the second embodiment. (A) is a diagram illustrating how interlocking occurs, (B) is an enlarged view ( 1 ) illustrating how interlocking occurs, and (C) is an enlarged view ( 2 ) illustrating how interlocking occurs. 
         FIG. 18  is a schematic diagram illustrating a configuration of a long wall according to the second embodiment. (A) is a cross-section view along B-B′, (B) is an enlarged cross-section view, and (C) is an enlarged cross-section view of the long wall bottom. 
         FIG. 19  is a schematic diagram illustrating a configuration of a conventional 8-unit block. (A) is a bottom view, (B) is a diagram illustrating assembly, and (C) is a bottom view. 
         FIG. 20  is a schematic diagram illustrating a configuration of an 8-unit block according to the third embodiment. (A) is a bottom view and (B) is a side view. 
         FIG. 21  is a schematic diagram illustrating a configuration of an 8-unit block according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     First Embodiment 
     As illustrated in  FIG. 1(C) , in an ordinary toy block, the base section C 3  is formed in a parallelepiped shape. For example, in the case of a toy block of conventional type such as Diablock (registered trademark), the base section C 3  of a 1-unit block C 1  is formed such that length×width×height=Cd 1 ×Cd 1 ×Cd 2 =4×4×3 (specifically, 8.0×8.0×6.0 mm), and this size is taken to be one unit size. The cylindrical projection C 2  is formed with a diameter Cd 3  of 5.0 mm and a height Cd 4  of 3.5 mm. 
     As illustrated in  FIG. 1(C) , the case of installing a lateral wall cylindrical projection C 2   x  on the lateral wall C 3 B of this 1-unit block C 1  of conventional type will be described. As illustrated in  FIGS. 1(D)  and (E), since the height differs in the horizontal direction and the vertical direction (length and height) of the parallelepiped, if some other block (hereinafter called “another block”) is assembled with respect to the lateral wall cylindrical projection C 2   x , a step is formed between the base sections C 3 . If another block is assembled, a ubiquitous gap is formed between 1-unit blocks C 1  due to the lateral wall cylindrical projection C 2   x  contacting the lateral wall C 3 B of the base section C 3 . 
     Even in the hypothetical case where the shape of the base section is simply taken to be length×width×height=Cd 1 ×Cd 1 ×Cd 2 =1×1×1, the lateral wall cylindrical projection C 2   x  butting into the lateral wall  3 B of the base section C 3  cannot be prevented, and a gap is formed. 
     In addition, the projecting portion of the lateral wall cylindrical projection C 2   x  interlocks inside the lateral walls C 3 B of the base section C 3  of another block. In other words, since the lateral walls C 3 B of the other block&#39;s base section C 3  hang off the lateral wall cylindrical projection C 2   x , simply decreasing size of the lateral wall cylindrical projection C 2   x  leads to the lateral wall cylindrical projection C 2   x  becoming unable to support another block. 
     The Applicant has discovered that by appropriately setting the relationship between the diameter and height of a cylindrical projection versus the wall width of the base section, another block can be made to firmly interlock with a lateral wall cylindrical projection, even in the case where a lateral wall cylindrical projection is provided on the lateral wall of the block. Hereinafter, an example will be described. 
     A toy block of the first through third embodiments comprises combining blocks of various units, such as 1-unit blocks, 2-unit blocks, 4-unit blocks, 8-unit blocks, 16-unit blocks, 32-unit blocks, and 64-unit blocks, and the present invention is applied to each unit block. Note that the units of a block may be a natural number, the value of which is not restricted. Note that the size tolerance is plus or minus 1.0%. 
     Besides such unit blocks, toy blocks may also include unusual blocks with unusual shapes. Note that hereinafter, the respective blocks of unit blocks and unusual blocks will be collectively called toy blocks. Preferably, highly elastic plastic such as ABS (Acrylonitrile-Butadiene-Styrene copolymer) plastic or acrylic plastic is used for all toy blocks. 
       FIG. 2  illustrates an overall configuration of a 1-unit block in the present embodiment. As illustrated in  FIG. 2(A) , the 1-unit block has a base section  3  with a parallelepiped shape overall, and a cylindrical projection  2  with a cylindrical shape that projects from the roof  3 A of the base section  3 . 
     As illustrated in  FIGS. 2(B) and 2(C) , the base section  3  is a cube with length×width×height=1×1×1. The unit edge length D 1  of the base section  3  is 6.0 mm, or in other words, the unit size is 6.0×6.0×6.0 mm. The cylindrical projection  2  has a diameter D 2  that is ½ the unit edge length D 1 , or 3.0 mm, and a projection height D 4  that is ½ the diameter D 2 , or 1.5 mm. The cylindrical projection  2  is chamfered along the edge of the circle on the upper face. Thus, safety is increased as a toy without sharp angles, while in addition, differences in dimension due to tolerances can be absorbed in the case where cylindrical projections  2  are built on in the vertical and horizontal directions. 
     As illustrated in  FIGS. 2(D) and 2(E) , the 1-unit block  1  has a hollow bottom. In other words, the 1-unit block  1  consists of one roof  3 A and four lateral walls  3 B, with the cylindrical projection  2  projecting from the roof  3 A. The cylindrical projection  2  is provided at the center of the roof  3 A, and the distance D 3  from a lateral wall  3 B to the edge of the cylindrical projection  2  is 1.5 mm in all cases. Note that the projection hole section  6  is not necessary. 
     As illustrated in  FIG. 2(D) , inside the base section  3 , the space of an interlocking section  5  formed by the four lateral walls  3 B and a projection hole section  6  are joined. The lateral walls  3 B have an approximately uniform thickness overall, and that thickness T 1  is ¼ the unit edge length D 1 , or 1.5 mm. 
     The horizontal inter-wall distance D 5  of the interlocking section  5  ( FIG. 2(E) ) is ½ the unit edge length D 1  in every horizontal direction, or in other words identical to the diameter D 2  of the cylindrical projection  2 . Consequently, when a cylindrical projection  2  is inserted into the interlocking section  5 , that cylindrical projection  2  makes a 4-point contact on the inner faces of the lateral walls  3 B constituting the interlocking section  5 , and it becomes possible for the base section  3  to hold the cylindrical projection  2 . Note that the size of the interlocking section  5  in the horizontal direction is 3.0 mm×3.0 mm. 
       FIG. 3  illustrates a 1-unit block with a lateral wall projection  101 . The 1-unit block with a lateral wall projection  101  has a lateral wall cylindrical projection  102   x , of identical shape and identical size as the cylindrical projection  102 , on a lateral wall with a projection  103 Ba, which is one of the lateral walls among the four lateral walls  103 B. 
     Consequently, the 1-unit block with a lateral wall projection  101  is able to interlock not only the cylindrical projection  102  on the roof  103 A of another block but also its lateral wall cylindrical projection  102   x  with the interlocking section  5  of another block, making it possible to hold a total of two other blocks. In other words, with the 1-unit block with a lateral wall projection  101 , it becomes possible for the direction of blocks which could only be built upwards in the past to be assembled in two directions, as illustrated in  FIG. 4(A) . 
       FIG. 5  illustrates a 1-unit block with a lateral wall hole  201 . The 1-unit block with a lateral wall hole  201  has a lateral wall hole  209  joined to the space of the interlocking section  205  (not illustrated) on a lateral wall with a hole  203 Bb, which is one of the lateral walls among the four lateral walls  203 B. The diameter D 6  of the lateral wall hole  209  may be appropriately chosen according to material properties or wall thickness, but is nearly identical to the diameter D 2 , preferably plus or minus 3% of the diameter D 2 . In this embodiment, the diameter D 6  is 3.0 mm and equal to the diameter D 2  of the cylindrical projection  102 . Also, the depth of the lateral wall hole  209  is equal to the wall thickness T 1  of the lateral walls  203 B (1.5 mm). 
     Consequently, the 1-unit block with a lateral wall hole  201  is able to accept the insertion of a cylindrical projection on another block at not only its interlocking section  205  (not illustrated), but also its lateral wall hole  209 . In other words, with the 1-unit block with a lateral wall hole  201 , assembly becomes possible in which the direction of blocks, which could only be built in one direction in the past, is changed to a difference direction, as illustrated in  FIG. 4(B) . 
     As illustrated in  FIG. 4(C) , by including a 1-unit block with a lateral wall projection  101  and a 1-unit block with a lateral wall hole  201  in a toy block of this embodiment, the direction of cylindrical projections  2  can be increased and the direction of cylindrical projections  2  can be changed, therefore the freedom of assembly of the toy blocks can be significantly improved. 
     At this point, it is necessary to set the projection height D 4  less than or equal to the distance D 3  from a lateral wall  3 B to the cylindrical projection  2 , in order to keep the cylindrical projection  2  of a 1-unit block  1  inserted into the interlocking section  205  of the 1-unit block with a lateral wall hole  201  from contacting the cylindrical projection  2  of a 1-unit block  1  inserted into the lateral wall hole  209 . 
     Since the distance D 3  is half the distance which subtract the diameter D 2  of the cylindrical projections  2  from the unit edge length D 1  {(unit edge length D 1 −diameter D 2 )/2}, it is necessary that the projection height D 4  be less than or equal to {(unit edge length D 1 −diameter D 2 )/2}. 
     At this point, the 1-unit block with a lateral wall projection  101  will support a 1-unit block engaged in the horizontal direction. The lateral wall cylindrical projection  102  makes linear contact on the inner faces of the lateral walls  3 B of another block. For this reason, at first glance it appears that the holding strength of a 1-unit block engaged in the horizontal direction can be raised by increasing the projection height D 4  (see  FIG. 2(C) ) as much as possible. 
     However, an increase in the projection height D 4  requires an equivalent decrease in the diameter D 2 . If the diameter D 2  is overly decreased, the cylindrical projection  2  becomes needle-like, and the danger of puncturing one&#39;s hand may occur. Also, if the diameter D 2  is decreased, the wall thickness T 1  must be increased, requiring large amounts of material. 
     By having the diameter D 2  with respect to the unit edge length D 1  be 0.4 or greater, the cylindrical projection  2  does not become needle-like, and safety as a toy can be guaranteed. Also, it is further preferable for the diameter D 2  with respect to the unit edge length D 1  to be 0.45 or greater, in order to maintain the external appearance as a toy block. 
     By having the diameter D 2  with respect to the unit edge length D 1  be less than 0.6, a comparatively large wall thickness T 1  can be ensured. For this reason, a cylindrical projection projecting in the horizontal direction can suitably hold another block without the lateral walls  3 B deforming, even in cases where additional weight from the lateral walls  3 B is applied due to their own weight, etc. In order to reduce the material used while sufficiently ensuring the thickness of the wall thickness T 1 , it is further preferable to have the thickness of the wall thickness T 1  be less than 0.55. 
     A 1-unit block  1  of this embodiment is designed such that, for a unit edge length D 1 =1, the diameter D 2  of the cylindrical projection  2  is ½, the projection height D 4  is ¼, and the wall thickness T 1  is ¼. Thus, it is possible to mold a block with excellent proportions in the points of other block holding strength, appearance, safety, and material usage. 
     As illustrated in  FIG. 6 , a 2-unit block  11  has an outward shape like that of two 1-unit blocks  1  lined up. The 2-unit block  11  has a base section  13  with a parallelepiped shape and two cylindrical projections  12 . The cylindrical projections  12  have an identical shape to the cylindrical projection  2  of the 1-unit block  1 . 
     The base section  13  has the size of two conjoined 1-unit sizes, with edges in the one horizontal direction and the height being equal to the unit edge length D 1 , while the edges in the other horizontal direction is twice the unit edge length D 1 . Taking the unit edge length D 1  to be 1, the base section  13  has the size of length×width×height=1×2×1. Specifically, the length×width×height=6.0 mm×12.0 mm×6.0 mm, the wall thickness T 1 =1.5 mm, and the distance D 3 =1.5 mm. 
     As illustrated in  FIG. 6(E) , the 2-unit block  11  has an interlocking section  15  formed by the inner faces of the four lateral walls  13 B. Specifically, the size of the interlocking section  15  in the horizontal direction is 3.0 mm×9.0 mm. If the cylindrical projection of another block is inserted into this 2-unit block  11 , the cylindrical projection and the lateral walls  13 B contact at three points, holding the other block. 
     As illustrated in  FIG. 7 , in a 2-unit block with a lateral wall projection  111 A, a lateral wall cylindrical projection  112   x  is provided on a lateral wall with a projection  113 Ba having the short edge in the horizontal direction from among the four lateral walls  113 B. The shape of the lateral wall cylindrical projection  112   x  is identical to the cylindrical projections  12 . 
     As illustrated in  FIG. 8 , in a 2-unit block with lateral wall projections  111 B, two lateral wall cylindrical projections  112   x  are provided on a lateral wall with projections  113 Ba having the long edge in the horizontal direction from among the four lateral walls  113 B. 
     In addition, although not illustrated, in 2-unit blocks with lateral wall holes  211 A and  211 B, respective lateral wall holes  219  are provided on a lateral wall with holes  213 Bb having the short edge or long edge in the horizontal direction from among the four lateral walls  213 B, similarly to the 2-unit blocks with lateral wall projections  111 A and  111 B. The shapes of the lateral wall holes  219  are identical to the lateral wall hole  209  of the 1-unit block with a lateral wall hole  201 . 
     As illustrated in  FIG. 9 , an 8-unit block  21  has an outward shape of eight 1-unit blocks  1  lined up. The 8-unit block  21  has a base section  23  with a parallelepiped shape and eight cylindrical projections  22 . The cylindrical projections  22  have an identical shape to the cylindrical projection  2  of the 1-unit block  1 . 
     The base section  23  has the size of eight conjoined 1-unit sizes, with edges in the one horizontal direction being equal to twice the unit edge length D 1 , while the other edges in the other horizontal direction is four times the unit edge length D 1 . Taking the unit edge length D 1  to be 1, the base section  23  has the size of length×width×height=2×4×1. Specifically, the length×width×height=12.0 mm×24.0 mm×6.0 mm, the wall thickness T 1 =1.5 mm, and the distance D 3 =1.5 mm. 
     As illustrated in  FIGS. 9(E) and 10(A) , the 8-unit block  21  has an interlocking section  25  formed by the inner faces of the four lateral walls  23 B. Specifically, the size of the interlocking section  25  in the horizontal direction is 21.0 mm×9.0 mm. In the interlocking section  25 , a middle partition  27  that constitutes the interlocking section  25  together with the lateral walls  23 B is formed on the centerline in the longer direction. Insertion of cylindrical projections is made easier by having the middle partition  27  be slightly shorter than the lateral walls  23 B in the height direction. 
     The middle partition  27  is composed of two long walls  27 A in the longer direction, and four short walls  27 B that are orthogonal to the long walls  27 A and join the two long walls  27 A. As illustrated in  FIG. 10(D) , if the cylindrical projections of another block are inserted into this 8-unit block  21 , the four cylindrical projections positioned at the ends in the longer direction and the lateral walls  23 B contact at three points. Meanwhile, the other block is held such that the four cylindrical projections positioned inwardly in the longer direction and the lateral walls  23 B contact at two points. 
     The short walls  27 B are provided at the portions where the cylindrical projections of another block and the long walls  27 A contact, and suppress deformation of the long walls  27 A due to additional weight from those cylindrical projections. In other words, by having the shape of three conjoined hollow rectangles, the middle partition  27  is made to keep its strength as a middle partition  27  while reducing material usage. Note that the long walls  27 A may also be in a state of extending out past the short walls  27 B. 
     As illustrated in  FIG. 11 , a 4-unit block  31  has an outward shape of four 1-unit blocks  1  lined up. The 4-unit block  31  has a base section  33  with a parallelepiped shape and four cylindrical projections  32 . The cylindrical projections  32  have an identical shape to the cylindrical projection  2  of the 1-unit block  1 . 
     In the base section  33 , edges in the horizontal direction are equal to twice the unit edge length D 1 . Taking the unit edge length D 1  to be 1, the base section  33  has the size of length×width×height=2×2×1. Specifically, the length×width×height=12.0 mm×12.0 mm×6.0 mm, the wall thickness T 1 =1.5 mm, and the distance D 3 =1.5 mm. 
     As illustrated in  FIG. 11(E) , the 4-unit block  31  has a middle partition  37  inside the interlocking section  35  formed by the inner faces of the four lateral walls  33 B. The length of the middle partition  37  in the height direction is identical to the middle partition  27  in the 8-unit block  21 . Although the middle partition  37  has an I-shaped construction, it may also be a hollow rectangle similar to the middle partition  27 . 
     As illustrated in  FIG. 12 , in an 8-unit block with lateral wall projections  121 , four lateral wall cylindrical projections  122   x  are provided on a lateral wall with projections  123 Ba having the long edge in the horizontal direction from among the four lateral walls  123 B. The shape of the lateral wall cylindrical projections  122   x  is identical to the cylindrical projections  12 . Furthermore, although not illustrated, two lateral wall cylindrical projections  122   x  may also be provided on a lateral wall with projections  123 Ba having the short edge in the horizontal direction from among the four lateral walls  123 B. The 4-unit block with lateral wall projections  131  is also similar, and two lateral wall cylindrical projections  132   x  may be provided on any lateral wall with projections  133 Ba. 
     In addition, as illustrated in  FIG. 13 , in an 8-unit block with lateral wall holes  221 , four lateral wall holes  229  are provided on a lateral wall with holes  223 Bb having the long edge in the horizontal direction from among the four lateral walls  223 B, similarly to the 8-unit block with lateral wall projections  121 . The shape of the lateral wall holes  229  is identical to the lateral wall hole  209  of the 1-unit block  201 . Furthermore, although not illustrated, two lateral wall holes  229  may also be provided on a lateral wall with holes  223 Bb having the short edge in the horizontal direction from among the four lateral walls  223 B. 
     As illustrated in  FIG. 14 , in a 4-unit block with lateral wall holes  231 , two lateral wall holes  239  are provided on a lateral wall with holes  233 Bb, which is one edge in the horizontal direction from among the four lateral walls  233 B, similarly to the 4-unit block with lateral wall projections  131 . The shape of the lateral wall holes  239  is identical to the lateral wall hole  209  of the 1-unit block  201 . 
     Although lateral wall cylindrical projections may also be formed on two or more lateral walls, they are preferably formed on only one. This is because construction as a toy block cannot become simplistic if lateral wall cylindrical projections are formed on multiple faces. 
     Lateral wall holes are also similar, and although they may be formed on two or more lateral walls, they are preferably formed on only one. This is because the appearance as a toy block can be kept by not outwardly exposing unused lateral wall holes. 
     As illustrated in  FIG. 15 , a 16-unit block  51  has an outward shape of sixteen 1-unit blocks  1  lined up. The 16-unit block  51  has a base section  53  with a parallelepiped shape and sixteen cylindrical projections  52 . The cylindrical projections  52  have an identical shape to the cylindrical projection  2  of the 1-unit block  1 . 
     Middle partitions  57 X may be provided on every row as part of the interlocking section  55 , as illustrated in  FIG. 15(B) , or middle partitions  57 Y may also be partially provided, as illustrated in  FIG. 15(C) . In addition, middle partitions  57 Z may also be configured with just one long wall  57 A, as illustrated in  FIG. 15(D) . These configurations of middle partitions  57  may also be applied to blocks of any units, such as 4-, 8-, and 32-unit blocks. 
     According to the above configuration, the base section  3  of the 1-unit block  1  of the present invention is configured such that, taking the unit edge length D 1  to be 1 and a cube expressed as 1×1×1 to be one unit size, or in other words a 1-unit block  1 , the base section  3  has a parallelepiped shape in which one or multiple unit sizes are conjoined, being composed of an open, hollow face taken to be the bottom, four lateral walls  3 B, and a roof  3 A. 
     The cylindrical projection  2  has a cylindrical shape and is provided on the outer face of one or more of the roof  3 A and lateral walls  3 B, with its diameter D 2  being equal to or greater than 0.4 but less than 0.6 with respect to the unit edge length D 1 , and its height being (1−diameter)×(0.4 to 0.5 inclusive). 
     The interlocking section  5  is enclosed by the four lateral walls  3 B, and by contacting and interlocking with another cylindrical projection X 2  of identical shape to the cylindrical projection  2  with respect to at least one of the lateral walls  3 B, holds that cylindrical projection X 2 . Additionally, of the interlocking section, the wall thickness T 1  near the bottom of a lateral wall  3 B contacting and holding the other cylindrical projection X 2  is expressed as (1−diameter)×0.5+alpha, where alpha is between −0.05 and 0.03 inclusive, and more preferably, alpha is between −0.02 and 0.01 inclusive. Stated differently, the wall thickness T 1  is approximately (1−diameter)×0.5. Note that an alpha may occur in the case of uniformly reducing the dimensions of the base section in each unit block from their unit sizes, or in the case of designing the inter-wall distance D 5  to be less than the diameter D 2 , for example, and in the present embodiment, the alpha is zero. 
     Thus, when the interlocking section  5  of the 1-unit block  1  interlocks with another cylindrical projection X 2  projecting out in the horizontal direction, the other cylindrical projection X 2  can be firmly held by the holding force due to the balance between the diameter D 2  and height D 4  of the other cylindrical projection X 2  as well as the thickness of the wall thickness T 1 , even though the size of the other cylindrical projection X 2  is small due to constraints for projecting cylindrical projections  2  vertically and horizontally. 
     The cylindrical projection  2  has a diameter that is equal to or greater than 0.45 but less than 0.55, and a height that is (1−diameter)×(0.45 to 0.5 inclusive). Thus, the 1-unit block  1  is able to hold another cylindrical projection X 2  much more reliably due to this balance. 
     The parallelepiped shape of the base section  23  consists of a shape of conjoined unit sizes of at least 2×2 or greater, while the interlocking section  25  has a middle partition  27  that contacts other cylindrical projections X 2  in the interlocking section enclosed by the four lateral walls  23 B. Thus, other cylindrical projections X 2  can be reliably held, even in a unit block having two or more rows of cylindrical projections  22  in the shorter direction, such as the 8-unit block  21 , for example. 
     In the 1-unit block with a lateral wall projection  101 , a lateral wall cylindrical projection  102   x  of nearly identical size as the cylindrical projection  102  is provided on at least one of the four lateral walls  103 B. Thus, with the 1-unit block with a lateral wall projection  101 , other blocks can be assembled not just vertically but also horizontally, potentially improving the freedom of assembly. 
     In the 1-unit block with a lateral wall hole  201 , a lateral wall hole  209  of nearly identical size as the cylindrical projection  202  is provided on at least one of the four lateral walls  203 B. Thus, with the 1-unit block with a lateral wall hole  201 , the direction in which cylindrical projections  202  project can be deflected 90 degrees, potentially improving the freedom of assembly. Note in this embodiment, diameter D 2  is slightly smaller than inter-wall distance D 5  preferably, since the interlocking section  5  can hold the cylindrical projection  2  more reliably. 
     Second Embodiment 
       FIGS. 16 to 18  illustrate a second embodiment which differs from the first embodiment illustrated in  FIGS. 2 to 15  in that a step is provided on the inner faces of the lateral walls  1023 B, and in the configuration of the middle partition  1027 . Note that in the second embodiment, signs with 1000 added are attached to portions that correspond to the first embodiment. 
     As illustrated in  FIGS. 16(A) to 16(C) , the lateral walls  1023 B are formed such that the angle between the inner face of a lateral wall  1023 B and a lateral wall bottom  1023 Ba at the bottom is cut out on the inner side of the lateral wall bottom  1023 Ba, and the cross section has a rectangular inner depression  1023 Bb. This inner depression  1023 Bb is provided along the inner side of the four lateral walls  1023 B enclosing the interlocking section  1025 , with one edge being 0.1 to 0.3 mm. Note that the shape of the inner depression  1023 Bb is not restricted, and the cross section may also have a triangular or circular cutout. 
     As illustrated in  FIG. 17(A) , the long walls  1027 A of the middle partition  1027  have outwardly bulging outward protrusions  1027 Ab at each region that does not interlock with the cylindrical projection X 2  of another block, which thereby form depressed interlocking depressions  1027 Ac only in regions where a cylindrical projection X 2  interlocks. 
     As illustrated in  FIG. 17(B) , a boundary line  1027 Aa is taken to be the extension extending parallel to a long wall  1027 A from the region of the long wall  1027 A that is farthest away from the lateral walls  1023 B (in other words, the maximally depressed part of an interlocking depression  1027 Ac). The inter-wall distance D 11  from the boundary line  1027 Aa to the inner face of a lateral wall  1023 B is formed slightly smaller (2.7 mm˜2.9 mm, for example) than the diameter D 2  (3.0 mm) of a cylindrical projection  1022 . The outward protrusions  1027 Ab project approximately 0.5 mm to 2.0 mm from the boundary line  1027 Aa at their maximally protruding part. 
     In addition, the opening distance D 12  from the intersection point of the lateral wall bottom  1023 Ba in the inner depression  1023 Bb ( FIG. 16(C) ) to the boundary line  1027 Aa ( FIG. 17(B) ) is formed equal to the diameter D 2  or slightly larger (3.0 to 3.1 mm, for example) than the diameter D 2 . 
     As illustrated in  FIG. 18 , the outward protrusions  1027 Ab are formed to project slightly from the region farther inward than the boundary line  1027 Aa of a long wall  1027 A (0.1 to 0.3 mm, for example), with their tips being formed at positions identical to or slightly inward (inward by 0.0 mm to 0.1 mm, for example) from the lateral wall bottom  1023 Ba. 
     For this reason, if a user attempts to insert the cylindrical projection X 2  of another block into the interlocking section  1025 , the cylindrical projection X 2  of the other block will be naturally inserted between the maximally projecting lateral walls  1023 B and the outward protrusions  1027 Ab in the bottom of the 8-unit block  1021 . 
     At this point, in the long walls  1027 A of the middle partition  1027 , the distance D 13  from the outward protrusions  1027 Ab to the lateral wall bottom  1023 Ba ( FIG. 17(B) ) is formed smaller than the diameter D 2  of a cylindrical projection X 2 . For this reason, cylindrical projections X 2  naturally fit inside the interlocking depressions  1027 Ac, and are guided to suitable positions inside the interlocking section  1025 . 
     Although cylindrical projections X 2  temporarily catch inside the inner depression  1023 Bb, since the step is small, they are easily inserted deeper past the inner depression  1023 Bb by the user&#39;s pushing action. Since the inter-wall distance D 11  is smaller than the diameter D 2  of a cylindrical projection X 2 , the lateral walls  1023 B continuously push against the cylindrical projections X 2 , firmly holding them. 
     At this point, since the wall thickness T 1  is designed to be sufficiently thick, there is little risk of plastic deformation of the lateral walls  1023 B. Additionally, there is little risk of plastic deformation due to the short walls  1027 B provided at the portions that contact a cylindrical projection X 2  in the middle partition  1027 . 
     The interlocking depressions  1027 Ac are trapezoidal depressions, and the legs of the trapezoid have a gentler slope than the curvature of a cylindrical projection X 2 . For this reason, an interlocking depression  1027 Ac is able to contact a cylindrical projection X 2  only at its maximally depressed point (line) and hold that cylindrical projection X 2 . 
     In other words, taking a contact point W to be the point positioned at the highest point on the page of the cylindrical projection X 2  on the page in  FIG. 17(B) , when the cylindrical projection X 2  moves left or right, the interlocking depression  1027 Ac is configured such that the interlocking depression  1027 Ac begins to slope and the distance between the interlocking depression  1027 Ac and the lateral wall  1023 B shortens before contact is made inside the interlocking depression  1027 Ac at sites other than the contact point W. For this reason, the cylindrical projection X 2  is substantially unable to move left or right, and its contact point with the interlocking depression  1027 Ac becomes just one point. 
     Note that the interlocking depressions  1027 Ac may also be such that the angled portions of the trapezoid are curved as in  FIG. 17(C) , or circular. It is sufficient for the sloped portions to be gentler than the curve of a cylindrical projection X 2 . 
     According to the above configuration, in an 8-unit block  1021 , it is configured such that the outward protrusions  1027 Ab are included on at least one face of the long walls  1027 A. The outward protrusions  1027 Ab acts as a guide mechanism and the position where other cylindrical projections X 2  contact on the boundary line  1027 Aa is maximally depressed. 
     Thus, the 8-unit block  1021  is able to moderately maintain holding force on another interlocked unit block without increasing the contact point between the other cylindrical projections X 2  and the long walls  1027 A and without the other cylindrical projections X 2  becoming misaligned in the horizontal direction. It is also possible to prevent the holding force from becoming excessive due to the increased number of cylindrical projections  1022 . 
     The inter-wall distance D 11  from a lateral wall  1023 B to a long wall  1027 A where one other cylindrical projection should be interlocked is formed slightly smaller than the diameter D 2  of a cylindrical projection  1022 . Thus, the smallness of the contact area with the interlocking section  5  due to the height smallness of the cylindrical projection  1022  is canceled, and another block can be firmly held. Although not illustrated, in this embodiment, the inter-wall distance D 5  between two lateral walls is formed slightly smaller than the diameter D 2  of a cylindrical projection  1022  in the case of a unit block with one row on its shorter edge. 
     Third Embodiment 
       FIGS. 20 and 21  illustrate a third embodiment which differs from the second embodiment illustrated in  FIGS. 16 to 18  in the wall thickness T 1  and the size of the cylindrical projection  2022  and in that the middle partition  2027  lacks short walls. Note that in the third embodiment, signs with 1000 added are attached to portions that correspond to the second embodiment. 
     As illustrated in  FIG. 19(A) , with respective unit blocks in a conventional toy block, no kind of barrier is provided, so that the cylindrical projections CX 22  of other blocks move parallel to the middle partition C 27 . For this reason, as illustrated in  FIG. 19(B) , there has been a problem in that the cylindrical projections C 22  and the cylindrical projections CX 22  of another block become misaligned in the case of assembling with the cylindrical projections C 22  in a shifted state. 
     Also, as illustrated in  FIG. 19(C) , it is known to provide linear guides, being linear protrusions, on the inner sides of the lateral walls C 23 B. However, since cylindrical projections CX 22  stop moving by contacting the linear guides COO, the number of contact points for the cylindrical projections CX 22  increases, and great force is required during removal. Or, when linear guides COO are small not to contact CX 22 , the liner guide COO cannot stop CX 22  moving enough. 
     As illustrated in  FIG. 20(A) , in an 8-unit block  2021  of this embodiment, the middle partition  2027  of the second embodiment is applied to the 8-unit block  2021  of identical configuration as a conventional unit block C 21 . Specifically, the 8-unit block  2021  is formed such that length×width×height=Cd 1 ×Cd 1 ×Cd 2 =4×4×3 (specifically, 8.0×8.0×6.0 mm). The cylindrical projection C 2  is formed with a diameter Cd 3  of 5.0 mm and a height Cd 4  of 3.5 mm, while the wall thickness of the lateral walls  2023 B is 1.5 mm. 
     The middle partition  2027  is configured with two long walls  2027 A only, and lacks short walls. By using plastic with comparatively high flexibility, such as polypropylene plastic or styrene plastic, for example, plastic deformation can be prevented even without short walls. 
     In this way, it is possible to prevent the cylindrical projections  20 X 2  of another block from moving parallel to the middle partition  2027 , even in the case of applying the middle partition  2027  of the second embodiment to a conventional unit block. Applying the middle partition  2027  is particularly effective for unit blocks having cylindrical projections  2022  with a diameter D 2  equal to or greater than 0.4 but less than 0.8, in which horizontal misalignment readily occurs. 
     According to the above configuration, in an 8-unit block  2021  having cylindrical projections  2022  with a diameter D 2  equal to or greater than 0.4 but less than 0.8, the wall thickness T 1  near the bottom of the lateral walls  2023 B is expressed as approximately (1−diameter)×0.5+alpha, where alpha is between −0.05 and 0.03 inclusive. Additionally, the 8-unit block  2021  is provided with outward protrusions  2023 Bb as a guide mechanism on at least one face of the lateral walls  2023 B and the long walls  2027 A constituting the interlocking section  2025 . 
     Thus, the 8-unit block  2021  is able to moderately maintain holding force on another interlocked unit block without the other cylindrical projections  20 X 2  becoming misaligned in the horizontal direction. It is also possible to prevent the holding force from becoming excessive due to the increased number of cylindrical projections  2022 . 
     Other Embodiments 
     Note that according to the second embodiment discussed above, the case of providing outward protrusions  1027 Ab on the 8-unit block  1021  was described. The present invention is not limited thereto, and the outward protrusions  1027 Ab may be applied to all blocks with two or more rows of cylindrical projections, such as 4, 6, 10, 12, 16, and so on. Similarly for the third embodiment, the outward protrusions  2027 Ab may be applied to unit blocks consisting of various numbers. 
     Also, according to the second embodiment discussed above, the case of providing inner depressions  1023 Bb on the 8-unit block  1021  was described. The present invention is not limited thereto, and similar advantages can be obtained by applying the above to respective unit blocks in the first and third embodiments. Also, as illustrated in  FIG. 21 , similar advantages can be obtained even by providing the outward protrusions  1027 Ab on the inner sides of the lateral walls  1023 B. 
     Furthermore, according to the first through third embodiments discussed above, the case of having one unit size be equal to the size of a 1-unit block was described. The present invention is not limited thereto, and is unrestricted insofar as it is within the size range of the present invention. For example, rather than sizes which are a natural number multiple of the 1-unit size, it is also possible to form blocks which are smaller by a given size (0.1 mm, for example) in just the horizontal direction. In other words, a 1-unit block becomes 5.9×5.9×6.0 mm in size, a 2-unit block becomes 5.9×11.9×6.0 mm in size, and a 4-unit block becomes 11.9×11.9×6.0 mm in size. In this case, adjustment is conducted with the wall thickness T 1  rather than the inter-wall distance D 5 , and is reflected in the value of alpha. Thus, it is possible to absorb size differences due to tolerances in the horizontal direction. In this example, the adjustment becomes alpha=(−0.1/6)/2+inter-wall distance D 5  for a 1-unit block. 
     Furthermore, in the third embodiment discussed above, the case of having the 1-unit size be 8.0×8.0×6.0 mm was described. The present invention it not limited thereto, and the present invention is applicable to unit blocks of various other sizes. 
     INDUSTRIAL APPLICABILITY 
     The present invention can be utilized for various toy blocks which can be assembled. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1 : 1-unit block 
               2 ,  12 ,  22 ,  32 ,  52 ,  102 ,  202 ,  1022 : cylindrical projection 
               3 ,  13 ,  23 ,  33 ,  53 ,  103 ,  203 ,  1023 : base section 
               3 B,  13 B,  23 B,  33 B,  53 B,  103 B,  203 B,  1023 B: lateral wall 
               3 A,  13 A,  23 A,  33 A,  53 A,  103 A,  203 A,  1023 A: roof 
             T 1 : wall thickness 
             D 1 : unit edge length 
             D 2 : diameter 
             D 5 : inter-wall distance