CN113531324A

CN113531324A - Combined display screen system

Info

Publication number: CN113531324A
Application number: CN202110795750.2A
Authority: CN
Inventors: 余朝亮; 艾骏
Original assignee: Shenzhen Divoom Technology Co ltd
Current assignee: Shenzhen Divoom Technology Co ltd
Priority date: 2021-07-14
Filing date: 2021-07-14
Publication date: 2021-10-22
Anticipated expiration: 2041-07-14
Also published as: CN113531324B

Abstract

The utility model relates to a combined display screen system, it includes a plurality of installing supports, the lateral wall that installing support is close to each other is opened there is the connecting hole, the installing support splices into whole mutually, be fixed with a plurality of display module on the installing support, work as the back is assembled mutually to the installing support, display module is complete plane, display module includes host computer module and auxiliary engine module, be connected with the connecting block between the display module, be equipped with connecting circuit board in the connecting block, be equipped with control circuit board in the display module, it is adjacent control circuit board in the display module passes through connecting circuit board and links to each other. This application has the effect of the more convenient transportation of display screen.

Description

Combined display screen system

Technical Field

The application relates to the field of display screens, in particular to a combined display screen system.

Background

In public places such as large squares, in order to show advertisement contents more prominently, a large display screen is usually arranged on a building or a square open space to play advertisements, so as to achieve a better showing effect.

The display screen system comprises a mounting bracket fixed on a wall or on the open ground, the display screen is fixedly connected onto the mounting bracket, when the display screen system needs to be mounted, the mounting bracket is fixed on the wall or the open ground, then the display screen is mounted on the mounting bracket, and the display screen is controlled by a circuit inside the display screen, so that the advertisement content is displayed.

In view of the above-mentioned related art, the inventor believes that the display screen has the defects of large volume and inconvenient transportation.

Disclosure of Invention

In order to make the display screen more convenient to transport, this application provides a combination display screen system.

The application provides a combination display screen system adopts following technical scheme:

the utility model provides a combined display screen system, includes a plurality of installing supports, the lateral wall that the installing support is close to each other is opened there is the connecting hole, the installing support splices into whole mutually, be fixed with a plurality of display module on the installing support, work as the installing support is spliced the back mutually, display module is complete plane, display module includes host computer module and auxiliary engine module, be connected with the connecting block between the display module, be equipped with connecting circuit board in the connecting block, be equipped with control circuit board in the display module, it is adjacent control circuit board in the display module passes through connecting circuit board and links to each other.

Through adopting above-mentioned technical scheme, after passing through the connecting block concatenation with display module, on installing another installing support with same group display module again, install the installing support again on the wall in proper order at last again to accomplish the installation of display screen. The setting of connecting block, make the split become the display screen of a plurality of display module need not on the basis of physical connection when connecting, the rethread electric wire connection realizes the signal of telecommunication intercommunication, make display module assemble more easily, and the display screen shell split becomes the polylith, make the display screen shell transport after the split, make the transportation of display screen more convenient, and when display screen part wearing and tearing need to be changed, only need to change wherein partial display module can, and need not to maintain or change whole display screen, be favorable to reducing cost of maintenance, make the display screen maintain more easily.

Preferably, the display module comprises an installation shell, the control circuit board is fixed in the installation box, an installation groove for inserting the connecting block is formed in the back face of the installation shell, the connecting column is arranged in the installation groove, and when the connecting block is inserted in the installation groove, the upper surface of the connecting block is flush with the back face of the installation shell.

Through adopting above-mentioned technical scheme for the display screen after the concatenation is more approached to whole, makes the back of the display screen after the concatenation more level and smooth, is favorable to reducing the protruding part and cuts the condition of hindering the people, and smooth surface is installed with the installing support laminating more easily.

Preferably, the connecting block inside wall is equipped with inlet post and outlet post, locate main stopper and vice stopper in the mounting groove respectively, inlet post and one of them display module main stopper grafting chucking, outlet post and adjacent display module vice stopper grafting chucking.

Through adopting above-mentioned technical scheme for the connecting block is pegged graft in the mounting groove more firmly, is favorable to reducing the connecting block and breaks away from the circumstances that leads to the whole circuit board steadiness after assembling to reduce with the installation shell.

Preferably, the connecting hole is in a notch shape, and the length direction of the connecting hole is consistent with that of the mounting bracket.

Through adopting above-mentioned technical scheme, when needs transport the installing support, thereby can pass the connecting hole with the hand and grip the installing support for the installing support is carried more easily.

Preferably, the both ends of installing support edge length direction are fixedly connected with bottom plate respectively, bottom plate fixedly connected with intermediate plate, the setting of intermediate plate perpendicular to bottom plate, one side fixedly connected with that the intermediate plate is kept away from the bottom plate can with the butt board of wall laminating butt, the bottom plate is seted up with the screw hole on the wall just right third screw hole.

Through adopting above-mentioned technical scheme, be favorable to increasing the area of contact of installing support and wall to improve the installation stability of installing support.

Preferably, a first through hole penetrates through the bottom plate, a second through hole penetrates through the middle plate, and the first through hole is opposite to the third threaded hole.

Through adopting above-mentioned technical scheme, be favorable to reducing the panel that consumes when making the installing support, simultaneously, when needs run through the third screw hole with the bolt, can install through first through-hole for the installing support is fixed on the wall more easily.

Preferably, the bottom plate runs through the fourth threaded hole that is used for connecting the display module frame and links to each other, the butt joint board has seted up the hole of stepping down, the hole of stepping down with the fourth threaded hole is just right.

Through adopting above-mentioned technical scheme, the setting in hole of stepping down is favorable to alleviateing the weight of installing support, and can pass the hole of stepping down and operate when twisting the bolt into third screw hole for display module's frame is fixed more easily.

Preferably, the two sides of the mounting bracket along the width direction are respectively provided with a positioning column and a positioning hole, when the adjacent mounting brackets are assembled, the side walls of the mounting brackets are abutted, and the positioning columns are inserted into the positioning holes of the adjacent mounting brackets.

Through adopting above-mentioned technical scheme, peg graft the reference column in the locating hole of adjacent installing support for adjacent installing support aligns more easily assembling the in-process, is favorable to assembling into a whole with display module, makes the display screen assemble more easily.

Preferably, the mounting bracket comprises a mounting plate, a mounting hole for the display module to be inserted is formed in the mounting plate, and the back face of the mounting plate is fixedly connected with the longitudinal partition plate and the transverse partition plate.

Through adopting above-mentioned technical scheme, the strengthening rib of mounting panel can be regarded as to vertical partition board and cross slab, strengthens the intensity of mounting panel for display module is more firm installs on the installing support.

Preferably, the two ends of the bottom plate along the length direction are respectively and fixedly connected with a first side plate and a second side plate, and the ends, far away from the bottom plate, of the first side plate and the second side plate are connected with the butt joint plate.

Through adopting above-mentioned technical scheme, first curb plate and second curb plate can support the butt joint board to as the connection structure of bottom plate and butt joint board, improve the intensity of butt joint board and bottom plate, reduce the condition that the butt joint board takes place deformation.

In summary, the present application includes at least one of the following beneficial technical effects:

1. the display screen shell is split into a plurality of pieces, so that the display screen shell is transported after being split, the transportation of the display screen is more convenient, when the display screen is partially worn and needs to be replaced, only part of the display modules are needed to be replaced, the whole display screen does not need to be maintained or replaced, the maintenance cost is favorably reduced, and the display screen is easier to maintain;

2. the spliced display screen is closer to the whole, so that the back of the spliced display screen is smoother, the situation that the protruding part hurts people is reduced, and the smooth surface is easier to be attached to and mounted on the mounting bracket;

3. the setting of first through-hole is favorable to reducing the panel that consumes when making the installing support, simultaneously, when needs run through the third screw hole with the bolt, can install through first through-hole for the installing support is fixed on the wall more easily.

Drawings

FIG. 1 is a schematic diagram of the overall structure of a combined display screen system according to the present application;

FIG. 2 is a schematic view of a disassembled structure of a single mounting bracket and a display module;

fig. 3 is a schematic structural view of a display module and a connection block.

Description of reference numerals: 1. mounting a bracket; 2. a display module; 3. mounting a shell; 4. a control circuit board; 5. a light-transmitting plate; 6. mounting holes; 7. connecting holes; 8. a longitudinal partition plate; 9. a diaphragm plate; 10. a first through hole; 11. a card slot; 12. a first threaded hole; 13. a side dam; 14. a connecting beam; 15. a mounting frame; 16. a second through hole; 17. a third threaded hole; 18. a hole of abdication; 19. a first side plate; 20. a second side plate; 21. a positioning column; 22. positioning holes; 23. a second threaded hole; 24. mounting grooves; 25. a main interface; 26. connecting blocks; 27. a tightening strip; 28. a butt joint plate; 29. inserting the column; 30. an inlet post; 31. an outlet post; 32. a main limiting block; 33. a skew prevention column; 34. an auxiliary limiting block; 35. a primary exit identity; 36. a primary import designation; 37. a reinforcing groove; 38. a middle plate; 39. a third through hole; 41. a secondary import identity; 42. a secondary exit identity; 43. a base plate.

Detailed Description

The present application is described in further detail below with reference to figures 1-3.

The embodiment of the application discloses a combined display screen system.

Referring to fig. 1, a combined display screen system includes a plurality of installing supports 1, 14 display modules 2 are fixedly connected to the installing supports 1, the installing supports 1 are mutually assembled to form an integral fixing frame, and the display modules 2 are assembled to form a complete display screen on the installing supports 1.

Referring to fig. 2 and 3, the display module 2 includes a mounting shell 3, the mounting shell 3 is hollow and has an opening on one side, a control circuit board 4 and a light-transmitting plate 5 inserted into the opening are mounted inside the mounting shell 3, and the light-transmitting plate 5 is a light-transmitting frosted plastic plate.

Referring to fig. 2 and 3, the mounting shell 3 is rectangular, and a circular clamping groove 11 is formed on one side of the mounting shell 3 away from the opening, so that the back of the mounting shell 3 forms a step shape.

Referring to fig. 1, installing support 1 includes the mounting panel and fixes vertical partition 8 and the cross slab 9 at the mounting panel back, and 14 partial shipment holes have been seted up to the mounting panel and have been supplied display module 2 to insert the installation, and after display module 2 installed on installing support 1, the lateral wall butt of each other that adjacent display module 2 is close to, and the perisporium in partial shipment hole is pegged graft in draw-in groove 11 to the degree of depth that restriction installation shell 3 inserted installing support 1.

Referring to fig. 2, the longitudinal partition plate 8 is provided with one, the transverse partition plate 9 is provided with 6, the longitudinal partition plate 8 and the transverse partition plate 9 divide the back of the mounting plate into 2 × 7 squares together, and the longitudinal partition plate 8 and the transverse partition plate 9 are perpendicular to the mounting plate, so that the strength of the mounting plate is increased as a reinforcing rib of the mounting plate, and the bending deformation of the mounting plate is reduced. The diapire of installation shell 3 runs through there are four second screw holes 23, and the mounting panel runs through have with the second screw hole 23 of installation shell 3 just right first screw hole 12, when needs fix display module 2 on installing support 1, aim at second screw hole 23 with first screw hole 12 to can fixed mounting shell 3 through the bolt.

Referring to fig. 2, two sides of the mounting bracket 1 along the width direction are respectively and fixedly connected with a side baffle 13, the side baffle 13 penetrates through two connecting holes 7 along the thickness direction, the two connecting holes 7 are located at two ends of the side baffle 13 along the length direction, the connecting holes 7 are in a notch shape, and the length direction of the connecting holes 7 is consistent with the length direction of the side baffle 13. After the side baffles 13 of the two adjacent mounting brackets 1 are attached and abutted, the two mounting brackets 1 are clamped and fixed through the matching of the bolts and the nuts, so that the adjacent mounting brackets 1 are spliced more easily, and meanwhile, when the mounting brackets 1 need to be moved, hands can pass through the connecting holes 7 to lift the mounting brackets 1, so that the mounting brackets 1 are carried more easily.

Referring to fig. 2, the both ends of mounting panel along length direction are respectively an organic whole to be connected with tie-beam 14, the length direction of tie-beam 14 is unanimous with the length direction of mounting panel, the one end fixedly connected with mounting bracket 15 of mounting panel is kept away from to tie-beam 14, mounting bracket 15 includes bottom plate 43 with tie-beam 14 fixed connection, bottom plate 43 is parallel with tie-beam 14, bottom plate 43 vertical fixation has intermediate plate 38, intermediate plate 38 is perpendicular to bottom plate 43, one side fixedly connected with that intermediate plate 38 keeps away from bottom plate 43 can with the butt plate 28 of wall laminating butt, butt plate 28 runs through there is third screw hole 17, when needs fixed mounting support 1, aim at the screw hole on the wall with third screw hole 17, and can fix installing support 1 on the wall through the bolt, increase the connection area with the wall simultaneously.

Referring to fig. 2, the bottom plate 43 has two first through holes 10 therethrough, the middle plate 38 has two second through holes 16 therethrough, the first through holes 10 and the second through holes 16 are square holes, the first through holes 10 communicate with the second through holes 16, and the first through holes 10 are aligned with the third threaded holes 17, so that the mounting bracket 1 can be more easily fixed on the wall by operating through the first through holes 10 when the bolts are screwed into the third threaded holes 17.

Referring to fig. 2, the two first through holes 10 are located at both ends of the bottom plate 43 along the length direction, and the bottom plate 43 has two fourth threaded holes penetrating therethrough, and the fourth threaded holes penetrate through bolts for fixing the outer frame of the display module 2. The abutting plate 28 is provided with a yielding hole 18, and the yielding hole 18 is opposite to the fourth threaded hole, so that the bolt can be fixed in the fourth threaded hole more easily.

Referring to fig. 2, two ends of the mounting plate along the length direction are respectively fixedly connected with a first side plate 19 and a second side plate 20, the first side plate 19 and the second side plate 20 are parallel to each other, the first side plate 19 and the second side plate 20 are both perpendicular to the middle plate 38, and one sides of the first side plate 19 and the second side plate 20 far away from the bottom plate 43 are both fixedly connected with the abutting plate 28. One side fixedly connected with reference column 21 that second curb plate 20 was kept away from to first curb plate 19, second curb plate 20 runs through to have and supplies reference column 21 to peg graft there is locating hole 22, when installation installing support 1, pegs graft adjacent reference column 21 in locating hole 22, can install again on the wall after a plurality of installing support 1 splices for display module 2 connects more easily.

Referring to fig. 2 and 3, a connecting groove is formed in one side, away from the light transmission plate 5, of the mounting shell 3, the connecting groove is a square groove, a main interface 25 is inserted into the connecting groove, a pin of the main interface 25 is welded to the control circuit board 4, and a socket of the main interface 25 protrudes into the connecting groove. The spread groove is established to four and is located four edges of installation shell 3 respectively.

Referring to fig. 1 and 3, a connecting block 26 is inserted in the connecting groove, a control circuit board 4 is arranged in the connecting block 26, two sides of the connecting block 26 are symmetrically inserted in the connecting groove of the adjacent mounting shell 3, the connecting block 26 is a square block, the peripheral wall of the connecting block 26 is integrally connected with a plurality of abutting strips 27, the abutting strips 27 are rectangular strips, and the connecting block 26 abuts against the side wall of the connecting groove through the abutting strips 27.

Referring to fig. 1 and 2, the connection block 26 is a casing with an opening at one side in the thickness direction, the connection block 26 is fixedly connected with a connection circuit board on the inner side wall opposite to the opening, the connection circuit board is fixedly connected with an auxiliary interface, and when the connection block 26 is inserted into the connection groove, the pins of the auxiliary interface are inserted into the sockets of the main interface 25.

Referring to fig. 1 and 3, the bottom wall of the connecting groove is further integrally connected with a plug column 29, the plug column 29 penetrates through a jack along the height direction to connect the main interface 25 and the auxiliary interface, the inner bottom wall of the connecting block 26 is integrally connected with an inlet column 30 and an outlet column 31 which are respectively used for being plugged in the periphery of the plug column 29 of the adjacent connecting block 26, the hollow auxiliary interface of the input end of the connecting circuit board penetrates out of the inlet column 30, the hollow auxiliary interface of the output end of the connecting circuit board penetrates out of the outlet column 31, the plug column 29 is in a hollow cylindrical shape, and the inner peripheries of the inlet column 30 and the outlet column 31 are both provided with abutting strips 27, so that the inner peripheries of the inlet column 30 and the outlet column 31 can abut against the outer periphery of the plug column 29.

Referring to fig. 1 and 3, the inserting column 29 is slot-shaped, wherein the three inserting columns 29 are used for the inlet column 30 to insert, the peripheral wall of the three inserting columns 29 used for the inlet column 30 to insert is fixedly connected with a main limiting block 32, the main limiting block 32 is located at one end of the inserting column 29 along the length direction, the peripheral wall of the outlet column 31 is opened for the main limiting block 32 to be clamped and inserted, so that the outlet column 31 is easier to align with the periphery of the inserting column 29 to insert with the inserting column 29.

Referring to fig. 1 and 2, the bottom walls of the inlet column 30 and the outlet column 31 are integrally connected with an anti-skew column 33, the anti-skew column 33 is hollow for the auxiliary interface to penetrate out, when the main interface 25 is communicated with the auxiliary interface, part of the outer peripheral wall of the main interface 25 extending into the connecting groove is abutted against the inner peripheral wall of the anti-skew column 33, so that the auxiliary interface pin is not prone to tilt in the process of inserting the main interface 25 into the main interface 25 and is difficult to align the pin with the socket for insertion, the process of mutually inserting the main interface 25 and the auxiliary interface is smoother, and the condition that the pin is bent due to the tilting of the interfaces is favorably reduced.

Referring to fig. 1 and 2, an auxiliary limiting block 34 is fixedly connected to the inner periphery of the insertion column 29 for inserting the outlet column 31, a gap is reserved on the peripheral wall of the skew-preventing column 33 for inserting and clamping the auxiliary limiting block 34, the auxiliary limiting block 34 is located at one end of the insertion column 29 in the length direction, and the outlet column 31 and the inlet column 30 are more easily distinguished through the arrangement of the main limiting block 32 and the auxiliary limiting block 34.

Referring to fig. 1 and 2, the bottom walls of three of the connecting grooves are marked with a main outlet mark 35, and the bottom wall of the other connecting groove is marked with a main inlet mark 36. Connecting block 26's back is carved with vice export sign 42 and vice import sign 41, vice import sign 41 and import post 30 are just setting up in connecting block 26 along the both sides of thickness direction, vice export sign 42 is just setting up in connecting block 26 along the both sides of thickness direction with export post 31, in this embodiment, vice import sign 41 and main export sign 35 are the circle form, vice export sign 42 and main import sign 36 are square form, because control circuit board 4 installs inside installation shell 3, be difficult to judge the direction of different interfaces when connecting block 26, make connecting block 26 install in the spread groove more easily.

Referring to fig. 1, reinforcing groove 37 has still been opened at the back of installation shell 3, and reinforcing groove 37 corresponds the spread groove and is equipped with four, and reinforcing groove 37 includes the trisection groove, divides the groove to be rectangular groove, and the trisection groove links to each other and forms the trapezoidal that surrounds the spread groove with the side of installation shell 3, is favorable to increasing the intensity of installation shell 3, reduces the condition that installation shell 3 was crushed.

Referring to fig. 2, the arrangement of the connection grooves forms a protrusion inside the mounting case 3, and the protrusion supports the control circuit board 4. The diapire is equipped with a plurality of fixed columns in the installation shell 3, and fixed column cavity and cavity inner wall are equipped with the screw thread, and control circuit board 4 has third through hole 39 along thickness direction running through, and control circuit board 4 utilizes protruding support control circuit board 4 through the bolt fastening with fixed column internal perisporium threaded connection, is favorable to reducing the condition that 4 warp of in-process control circuit board of the fixed control circuit board 4 of application of force.

The implementation principle of a combined display screen system in the embodiment of the application is as follows: when the display modules 2 need to be assembled, the inlet column 30 of the connecting block 26 is connected with one of the plug-in columns 29 of the mounting shell 3, which is provided with the main limiting block 32, in a plug-in manner, and then the outlet column 31 is connected with the plug-in column 29 of the other mounting shell 3, which is provided with the auxiliary limiting block 34, in a plug-in manner, so that the control circuit boards 4 in the two mounting shells 3 are in signal communication, and the physical connection and the electrical connection between the adjacent display modules 2 are realized. Then, penetrating the bolt through the first threaded hole 12 and the second threaded hole 23 simultaneously so as to sequentially mount the display module 2 on the mounting bracket 1, and penetrating the bolt through the third threaded hole 17 and in threaded connection with a threaded hole on the wall so as to fix the mounting bracket 1 on the wall; inserting the reference column 21 in the locating hole 22 of adjacent installing support 1 next, thereby splice installing support 1, make installing support 1 align more easily and assemble, pass the connecting hole 7 that the first curb plate 19 and the second curb plate 20 intercommunication of laminating mutually simultaneously with the bolt again, through screwing up the nut, nut and bolt cooperation take-up adjacent installing support 1, and fix installing support 1 on the wall through the bolt that runs through third screw hole 17 again, be favorable to reducing and install display module 2 in proper order at the wall, thereby lead to the condition that high altitude construction time becomes long, be favorable to shortening installation time, improve the efficiency of installation.

The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims

1. A combined display screen system is characterized in that: including a plurality of installing supports (1), the lateral wall that installing support (1) is close to each other is opened there is connecting hole (7), installing support (1) splices into whole mutually, be fixed with a plurality of display module (2) on installing support (1), works as installing support (1) assembles the back mutually, display module (2) are complete plane, display module (2) include host computer module and auxiliary engine module, be connected with connecting block (26) between display module (2), be equipped with connecting circuit board in connecting block (26), be equipped with control circuit board (4) in display module (2), it is adjacent control circuit board (4) in display module (2) link to each other through connecting circuit board.

2. The combination display screen system of claim 1, wherein: display module (2) is including installation shell (3), control circuit board (4) are fixed in the mounting box, mounting groove (24) that supply connecting block (26) to peg graft are opened at the back of installation shell (3), the spliced pole sets up in mounting groove (24), works as when connecting block (26) are pegged graft in mounting groove (24), connecting block (26) upper surface flushes with installation shell (3) back.

3. The combination display screen system of claim 2, wherein: connecting block (26) inside wall is equipped with inlet post (30) and export post (31), locate main stopper (32) and vice stopper (34) respectively in mounting groove (24), inlet post (30) and one of them display module (2) main stopper (32) chucking of pegging graft, export post (31) and adjacent display module (2) vice stopper (34) chucking of pegging graft.

4. The combination display screen system of claim 1, wherein: the connecting hole (7) is in a notch shape, and the length direction of the connecting hole (7) is consistent with that of the mounting bracket (1).

5. The combination display screen system of claim 1, wherein: installing support (1) is along length direction's both ends fixedly connected with bottom plate (43) respectively, bottom plate (43) fixedly connected with intermediate lamella (38), intermediate lamella (38) perpendicular to bottom plate (43) set up, one side fixedly connected with that bottom plate (43) are kept away from in intermediate lamella (38) can with butt board (28) of wall laminating butt, bottom plate (43) offer with the just right third screw hole (17) of screw hole on the wall.

6. The combination display screen system of claim 5, wherein: the bottom plate (43) penetrates through a first through hole (10), the middle plate (38) penetrates through a second through hole (16), and the first through hole (10) is opposite to the third threaded hole (17).

7. The combination display screen system of claim 5, wherein: the bottom plate (43) runs through the connected fourth threaded hole for connecting the outer frame of the display module (2), the abutting plate (28) is provided with the yielding hole (18), and the yielding hole (18) is just opposite to the fourth threaded hole.

8. The combination display screen system of claim 1, wherein: the mounting support is characterized in that positioning columns (21) and positioning holes (22) are respectively arranged on two sides of the mounting support (1) in the width direction, when the mounting support (1) is adjacent to the mounting support in an assembled mode, the side walls of the mounting support (1) are abutted in an attached mode, and the positioning columns (21) are inserted into the positioning holes (22) of the adjacent mounting support (1).

9. The combination display screen system of claim 1, wherein: the mounting bracket (1) comprises a mounting plate, a mounting hole (6) for the display module (2) to be spliced is formed in the mounting plate, and a longitudinal partition plate (8) and a transverse partition plate (9) are fixedly connected to the back of the mounting plate.

10. The combination display screen system of claim 5, wherein: bottom plate (43) are along length direction's both ends respectively fixedly connected with first curb plate (19) and second curb plate (20), the one end that bottom plate (43) were kept away from to first curb plate (19) and second curb plate (20) all links to each other with butt board (28).