US2319278A - Display board construction - Google Patents

Description

May 18 1943 L. F. uRBAlN 2,319,278

DISPLAY BOARD CONSTRUCTION INVENTOR.

ATTORNEYA May 18, 1943 L F.l URBAIN 2,319,278

' DISPLAY BOARD CO-NSTRUGTION Filed Oct. 18, 1.9259l 3 Sheets-Sheet 2 May 18, 1943 1. F. URBAIN 2,319,278

DISPLAY BOARD CONSTRUCTION M I Filed oct. 18. 19.39 :s sheets-sheet s ATTORNEY-5,

Patented May 18, 1943 i UNITED STATES PATENT OFFICEV DISPLAY BOARD CONSTRUCTION Leon F. Urbain, Chicago, Ill. Application october 1s, 1939, sena1N0.299,925

18 Claims.

The present invention relates to a display board construction and particularly to `a supporting frameconstruction and to certain elements and combinations of elements comprising the frame construction for display boards, blackboards, bulletin board, card panels and the like.

The present invention contemplates providing a display board supporting frame construction for mounting blackboards and similar construction elements adjacent ithe sub-surface of a supporting Wall or partition.

The structural arrangement of relatively extensive but thin slabs of slate and other blackboard materials presents serious problems, both in respect to fthe original facility Of assembly and mounting, as Well as the adequacy and permanence of support. It has hitherto been the practice to provide a supporting layer or series of contact points of some suitable plaster in back of the blackboard element per se, and then to apply a retaining trim. Various'gripping means have been used to engage adjacent the periphery of each blackboard slab, While being rigidly fixed to suitable ground strips. In each instance considerable diioulty is encountered in the initial assembly steps, Whereas dis-assembly for purposes of repair orreplalcement is even more difficult. So, also, the normal variation in'thickness of the blackboard slabs inherent in the slatesplitting Operations has necessitated extensive modifications in the prior prefabricated supporting elements where the outer surfaceof the board must be aligned in a carefully predetermined plane.

lit is `an important object of the present invention to Overcome the foregoing difficulties lby providing a blackboard frame construction readily applicable to any suitable Wall or partition surface and which freely receives a blackboard or bulletin slab for holding the slab positively [by means of resilient pressure.

It is la yet more specific object of the present invention to provide a gro-und or frame construction such as the above adapted to be received preferably flush with the outer surface of a iinished Wall, the ground Ibeing provided with uniformly distributed yielding or springmembers to peripherally receive the black-board unit as Well as retaining keys freely insertable into position to hold the board uniformly against the yielding spring cushions. In accordance with this arrangement, therefore, it will be apparent that having constructed the supporting ground the blackboard slab is finally mounted lby merely disposing it in the recess provided therefor and slipping the retaining keys into position.

It is a yet further object ofthe present inventionto provide an improved ground or framing vmemberconstructed for carrying out the' foregoing function and particularly such a construction unit adapted to receive plaster to conceal its points of attachment with the partition or wall. The present invention further contemplates the provision of outer trim members resilienltly engageable With retaining clips formed so as to internally grip adjacent Opposed lateral portions Off the trim at all times. 1` l Among other important objects of the present 'invention are to provide a combination Of yieldable slab supporting and backing members With a ground strip such that the spring members are 'positively located by virtue of their yieldable engagement with the ground strip; to providel a blackboard `ground construction which, While holding the blackboard slab as above, is so constructed as to provide separate mqldmg '01- trim 'strips free from any holding or retaining function; and to provide a construction' eliminating Wall condensation, particularly at localized areas. Yet other and further objects Will be more apparent from the following detailed description When-.considered in connection with the acom- Fig. 4 is a detailed perspective View of` a corner of the blackboard of Fig. 3 illustrating one method of joining the head trim with a jamb.

Fig. 5 is a detailed, sectional View taken on line 5-5 of Fig. 3.

Fig. 6 is a perspective vieW of a spring clip for retaining the trim or molding strip. Fig. '7 is a sectional, detailed View taken on line 'l-l vertically through the blackboard of Fig. 3.

Fig. 8 is a detailed, perspective View of the blackboard of Fig. 3, portions of the surface having been'freely broken away to show in detail the internal construction and arrangement of the parts.

Fig.9 is a sectional vieW taken in a similar location as Fig. 7, but showing a modified form of supporting channel.

Fig.'10 is a detailed, sectional view taken horizontally on line lil- I of Fig. 7 to show the detailed construction and arrangement of the yielding spring supports for the blackboard slab.

Fig. 11 is a perspective, detailed view of the end of the chalk tray showing in particular the construction of the end stop.

Fig. 12 is a perspective view of the end stop shown in dis-assembled relationship.

Fig. 13 is a sectio-nal view taken vertically on line I3--I3 of Fig. 11 to illustrate the means for joining the end stop to the tray.

Figs. 14, 15, 16 and 17 are perspective views of a map or supporting rail and slide construction which may be substituted for that shown in Fig. 8.

Figs. 18 and 19 are sectional views taken vertically through the rail and slide constructions shown in Fig. 17 on line I8-I8 thereof.

Fig. 19 further illustrates the removability of the slide.

Fig. 20 is a sectional, detailed view taken on line 20-20 of Fig. 16.

Fig. 21 is a sectional view taken centrally through an alternative form of trim strip.

Referring more particularly to the drawings wherein the present invention is illustrated more in detail, Figs. 1 and 2 disclose one preferred form of display board construction comprising a ground or supporting frame I0 receiving a blackboard slab I2 and also supporting a chalk tray I4 and an appropriate trim or mold strip construction I6. The ground is mounted upon any suitable wall or partition I8 by means of any Isuitable fastener 20. As shown in Fig. 2, the ground frame I 0 is preferably mounted upon the surface of a sub-Wall or partition just below the plaster surface 22 so that the outer surface of the ground is ultimately iiush with the surface of the plaster. With this construction the surface of the blackboard slab falls into co-planar disposition with respect to the associated wall for the sake of. a more pleasing aesthetic appearance, as will hereinafter more fully appear, and the trim strip alone projects outwardly of this plane.

Particular attention is directed to the construction of the so-called ground or frame and the structure of the strip material employed, for which purpose reference may be made to Fig. 8,.

which, while relating to an alternative embodiment of blackboard construction, nevertheless is formed from upper and lower ground strips of identical construction. It will be noted that these ground members have a central channel section provided by a flat, vertical wall surface 24 and spaced, laterally extending walls 26 and 28, terminating in a vertical flange parallel with the wall 24, and, therefore, parallel with the final wall surface and with the plane of the blackboard. While the flange 30 may be apertured to receive fasteners 32 for engagement with the sub-wall or partition, its function is primarily to support a plurality of yieldable springrnem.- bers 3S disposedv regularly therealong. One'. of the spring members 35 (see Fig. 10) is composed of a resilient, yieldable leaf gently and regularly curved at its central portions and terminating in oppositely curved contact sections 38. To receive the yieldable spring supports 36 the flange 30 is struck out as at 4d to shift a predetermined tongue of metal laterally into parallel spaced relation while remaining integrally connected with the flange 36 along one side edge only. Particular attention is directed to the fact that the formation of the struckv out portion results in an opposed recess or aperture 42 adapted to receive the central, curved portion of the spring leaf 36. It will be accordingly obvious that when the spring leaf is yieldably urged behind the struck out tongue 40 its central part springs into the aperture 42 and positively retains the parts in the position shown, whereas the curved portions 38 project outwardly t0 receive the blackboard slate, as will hereinafter more fully appear.

The upper, lateral ange 25 of the ground strip Ill terminates in a vertical attachment flange 44, similarly apertured to receive wall attachment fasteners 20. Here again it is important to note that the flange 25 forms an acute angle with the wall surface 24 which, in combination with the provision of a plurality of elongated apertures 48 at the juncture with flanges 26, provides for the inter-locking reception of the nal plaster surface 22.

The present ground strip construction provides simple and improved means for the positive retention of the blackboard slab against the yieldable cushioning springs in the form of a plurality of spaced locking keys or plates 50. Each of the keys or plates 50 in the present embodiment comprises a flat sheet member beveled at its lower corners as at 52 to facilitate entry into an engaging sheath or keeper 54 on the ground strip, and has at its upper extremity, as Viewed in the upper portion of Fig. 8, laterally projecting ears or stops 56. rEhe engaging sheath 54 is formed by striking out a portion of the area of the ground strip wall 24 to a parallel plane sufficiently spaced to receive the thickness of the retaining plate 59. The struck out strap 54 remains integral with the wall 24 at itslongitudinal extremities 58. It should be particularly noted that each of the embracing straps 54 is disposed in longitudinal alignment with one of the foregoing yieldable spring units in such position that the extremity of the keeper or plate 5D projects opposite the flange 30, as is clearly shown in Figs. 2 and 8. The foregoing cooperating elements confine, restrain and completely support the blackboard slab I2. Only the simplest of assembly operations are involved in arranging the periphery of the slab I2 against the regularly disposed yielding supports 33, shifting the blackboard rearwardly and then locking it in place by merely slipping the keeper ngers 50 through their retaining sheaths and into engagement with the front surface of the board.

The foregoing strip construction which I provide in accordance with the present invention may be arranged in the form of a rectangular ground by cutting head, base and jamb pieces of the proper length and fastening these to the partition in the rectangular arrangement shown. The corners may be mitered, as shown in Fig. 1, or may be alternatively joined by any suitable connecting coupling block or insert. Upon completion of plastering the ground thus formed provides a rectangular recess for the reception of the rectangular slab i2. rihere is provided, in accordance with the construction shown in Fig. 1, an insulating and preferably sound-proof layer 68 which, in accordance with my observations, eliminates condensation and drumming. While any suitable insulating and cushioning or soundproof board may be employed, I prefer the use of any of the well-known insulating quilts, such as those made of wool shoddy or other layers known as Capots quilt. It is preferred that the quilt be so disposed as to exert no 'urge the feather edge 93 intoi pressure line conappreciable pressure against the surface of the blackboard.

The trim construction I6 is formed of a plurality of strips having a channeled section with oppositely inturned edges 62, as shown in Fig. 2, embracing the opposite extremities of a retaining clip 64. The clip v64, shown in detail in Fig. 6, has a bowed central portion and opposite lateral margins conflgurated with rounded,

beaded sections 66. A central slot'68 permits vattachment to the central wall or web 24 of the ground strip by means of any self-threading fastener 1I). It is` vimportant to lnote, as clearly shown in Fig. 2, that the trim strip, when pressed over the clip 64 resiliently engages both of the resilient beads 66. At all times, therefore,

'the beads exert an opposite yieldable, internal pressure against the trim strip so that loosening or vibration is impossible.

- -The trim strip is cutin lengths corresponding to the jambs and headstrip of the ground, and the corners may be mitered, as shown in Fig. 1, or else brought into abutting inter-engagement with a corner block 'I2 co-extensive in sectional proportions with the trim strip and having projecting rails or lugs 'I4 receivable within the central, longitudinal recess thereof.

In the embodiment shown in Figs. 1 and 2, the lower trim function is effected by the chalk trough I4. ,The details of construction of this .trough appear more particularly in Figs. 2, 5, 8, 11, 12 and 13, to which reference is now made. -With the exception of a pair of end stops 16, the trough is composed of a continuous length of extruded material having a uniform section, indicated in Fig. 2.

It is to be particularly noted that the trough I4 has an upper supporting surface I8 which is inclined outwardly at a substantial angle sufficient so that chalk dust will gravitate downwardly or to the right,as viewed in Fig. 2. The surface is provided with a plurality of serrations or ridges 86, the lowermost serration defining a chalk groove 82 together with an upwardly extending loop portion of the rail section designated at 84. Attention is particularly directed 4to the fact that the loop or abutment section 84 extends reversely with respect to the downward inclination of the upper supporting surface to provide a stop or abutment for the eraser, as

lower portion. The upper extremity of the' trough similarly has a substantially vertical flange portion 92 which, due to the inclination of the supporting surface, forms a sharp, acuteA A section of the trough angle therewith. Particular attention is directedjV to the fact that the rear surface of the flange 92 makes an angle with the vertical exemplified in Fig. 5 by the letter B. A so-called feather edge 93 is thus provided for making a line pressure tact with the' surface of the board I2, while the lower bead 66 engages'behind flange extremity 90. For assembly purposes the flange 92 isy merely engaged behind the spring 96 and the flange 90 clipped over the bead 66. The end stops 'I6 shown in Figs. 11, 12 and 13 comprise a vertical end wall 98 having laterally extending margins projecting into congruity with the walls of the chalk trough. As more clearly shown in Figs. 11 and 13, the laterally extendingupper surface portion continuous with the supporting surface of the trough is recessed slightly as at |60 to provide a guideway or spout configuration for dust pro- `jected longitudinally across the extremityv of the trough. The facility with which the dust in the trough may be removed is evidenced by the fact that the cleaning device may be moved longitudinally in the lower groove 82 to direct the dust over the end stop into a suitable receptacle.

The end stops are provided with a plurality of lugs |62 engageable interiorly of the walls of the trough and adapted to receive fastenings |04.

Where the lower trim or mold is desired in addition to the trough, a compound base-ground construction is provided, as shown in Fig, 5, in which a second ground strip |06 is located above the ordinary base strip and provided with struck out lugs 40 mounting pressure clips 36 identical to those hitherto described. Strip |96 is otherwise provided with an outer, central wall 24a and a lateral wall 28a, the latter terminating in a vertical ange 30a which mounts the tongue and clip spring construction. It is to be noted that the lower flange 26a defines the lateral margin of the strip to facilitate nesting with the lower ground strip I0, as clearly shown in Fig. 5. Vertical alignment of the compound base-ground construction is positively maintained by a pin which may be an ordinary nail or driven fastener |98 disposed in vertically aligned apertures in the flanges 26a and lateral wall 28a and extending into a longitudinal slot III) in the upper lateral flange of the base ground strip. In accordance with this construction, the spring clip 94 supports the chalk trough upon the upper base ground |36 whereasthe lower ground mounts the spaced clips E4 which retain the lower trim strip IB. It will be seen that the lower, horizontal surface portion 88 of the trough thus cooperates with the upper, flat surface of the trim strip to reside in flatwise abutment. 'A

I have shown in Figs. '7 and 8.a modified form of board construction` embodying an indicia re ceiving slab I2 and in combination therewith a bulletin board I|2 for receiving posted bulletins, The boards or slabs are spacedby a horizontal ground strip I I4 equivalent in configuration with the foregoing strip I0 but havingupper and lower inner, vertical flanges 39a mounting pressure clips 36 in struck out tongues .40.. The board slabs are retained-against the pressure clip foundation by an outer display rail I IB secured to the ground I I4 by thread forming or tapping fasteners I I8. The rail is of simple channel configuration, as shown, having in-turned, marginal flanges I2!) to retain a plurality of slidable display fixtures or blocks |22.

The interengagement of the vblocks with the supporting rail is shown in detail in Fig. 18 wherein it will be noted that to the rear of a chamfered outer periphery |24 each block is provided with horizontal upper and Alower grooves or slots |26 and |28, respectively, (see Fig. 19) which grooves receive the in-turned flanges |26 of thev guide rail. The lower groove |28y is rendered relatively shallow by relieving as at |30 a portion of the rearward Wall defining the slot I 28. Each block, while thus slidably interengaged with the guide rail, is freely removable, as shown in Fig. 19, when shifted upwardly to dislocate the lower ange from the groove |28.

The slidable fittings |22 shown in Figs. 17, 18 and 19 are centrally apertured and counter-bored to receive a central plug or insert |32 which may be formed of cork or similar soft material for lreceiving such a fastener 'as a thumb tack. It is to be noted that the rearward faces of each of the blocks are relieved by a horizontally-extending groove |34 to permit the blocks to clear any projecting portions of the fasteners 0.

In accordance with the modied construction shown in Fig. i4, the blocks |22 are provided with hooks |36 projecting outwardly to suspend maps.

In a yet further modified embodiment, shown in Fig; l5, the blocks |22 are provided with spring clips |38 comprising base strips |40 fixed rigidly upon the block. In using these clips the upper edges of papers or maps may be suspended by clipping them under the yieldable portions |33. It will be evident that in each instance any number of sliding blocks |22 may be provided longitudinally at will to provide the desired number of supporting points.

A further modification which I have shown for illustrative purposes in Figs. 16 and 17 comprehends the provision of adjustable supports for a roller suitable for mounting and supporting roller mounted maps and the like. In accordance with this construction, each of the blocks |22 is provided with brackets |44 for receiving the roller |46. Each bracket is rigidly held in each block |22 by fasteners |48 (see Fig. 20). I have discovered that it is desirable and sometimes important to positively determine the spacing of each pair of brackets when supporting a roller. To this end I supply for each block |22 a knurled thumb screw |50 threadedly received in the block and bracket for frictional engagement with the rear face of the guide rail or channel H5. While the thumb screw is normally rotationally retracted to permit sliding adjustment of the blocks when arranged in the desired position, the screw may be tightened to locate the unit in position.

It will be evident from the foregoing that my guide rail IE6 may be substituted for the upper or head trim I6 in any of the foregoing embodiments where elevated bulletin means are desired and I have shown in Fig. 9 a modification adapted peculiarly for this purpose and designated by reference numeral |54. It will be seen that the rail |54 is conigurated adjacent its rearward portions substantially identically with the trim I6 for engagement upon retaining clip 64. In accordance with the present embodiment, the forward portion of the rail is provided with a pair of spaced channel sections ISE and |58 separated by a central partition wall |00 terminating in a transverse, oppositely extending flange |62. The lower guideway or channel may receive any suitable blocks |22, as hereinbefore mentioned, while the upper channel may be, and is in the embodiment shown, caused to embrace a strip of cork or similar material adapted to receive tacks for fastening.

I have disclosed in Fig. 2l one illustrative modification of the trim strip to clearly illustrate and exemplify some of the Awide variations possible in'accordance with the practical and aesthetic demands. In general, the trim shown in section in Fig. 1 differs from the trim strip I6 in providing a curved, outer wall |52.

Where a bulletin receiving or posting board H2 is employed, it is supported by pressure springs 36. In accordance with the illustrated embodiment of Fig. 8, it is preferred that some rigid backing be provided in any conventional manner.

Throughout the specification and claims it will be evident that the term display board or blackboard slab is intended to be used to cover not only surfaces adapted to receive indicia by marking, but also other supporting boards, particularly those adapted for wall display purposes. In other words, the term includes blackboards, bulletin boards and screens of various types such as are employed in class rooms, markets and the like.

From the foregoing it will be evident that the present invention provides for the rapid assembly and erection of such blackboard units from stock parts which may be cut to length for any particular job. After the erection of the ground by merely fastening four marginal ground strips to the sub-wall, permanent mounting of the board is eiTected by urging the display board against the yieldable, peripheral spring seats in the recess thus provided and associating the latches or keys 50 within each sheath provided therefor. The board is at this time positively aligned in iiush relation with the outer plane of the ground and accordingly with the outer surface of the finished Wall. At this time the clips 64 are applied and the trim strips snap into position to completely conceal underlying supports.

It is thought obvious from the foregoing that the present construction provides substantially theoretically ideal conditions for mounting slabs having the peculiarities characteristic of blackboards. Thus the slab, While positively positioned, is, nevertheless, held by a carefully predetermined pressure at points regularly peripherally spaced. Compensation is thus made for the unavoidable and usual variations in the thickness of the slab or any changes which may occur, and the element is ideally supported for yresistance to shock or vibration. As pointed out previously, the present invention provides an insulation which solves the structural problems known as wall condensation and drumming.

It is further important to note that the present chalk trough assembly positively accumulates chalk dust which normally might settle Within internal crevices by directing these particles on to the downwardly inclined receiving surface of the trough and to a receiving groove provided therefor. The eraser in spaced relation to the receiving groove thus rests upon a supporting surface relatively clean and free of dust.

Of even greater importance, however, is the fact that the chalk trough, because of its inclined position, presents the eraser at all times facing the student who, being normally in front of the blackboard, directs his attention toward the eraser trough at a downward angle. Thus the eraser is not only in plain view and more easily accessible but, at the same time, is spaced and located a substantial distance from the blackboard. It will be realized that this is of great practical significance in view of the objectionability of contacting the lingers and particularly the finger nails with a slate or similar surface or with associated molding, as has hitherto been `the `frequent case.

With the present construction the eraser will always gravitate downwardly to the abutment rail 84 in a position where it is instantly accessible and free from inadvertent undesirable contact with the blackboard.

It is further of great importance to note that the foregoing knife edge lip construction 93 making a line contact with the blackboard provides an integral dust deflector whereby all falling and settling chalk dust is directed downwardly into the receiving groove 82 provided therefor. This provides a clean, sanitary constructi-on as opposed to those prior constructions wherein the objectionable and pathologically harmful dust particles were normally permitted to collect within or adjacent the trim or other portions of the blackboard assembly, either internally or externally, wherein they could not be cleaned away and removed.

Another important new result iiowing from the inclined supporting surface configuration of the foregoing chalk trough resides in the facility with which this surface may be abuttingly associated with the trim `and other strips. Thus it should be noted that the angle of the eraser supporting or dust deecting surface is equal to 45 degrees. Therefore, when assembling blackboard constructions, such as shown in Fig. 1, in which the side trim strips abut the chalk trough at their lower extremities, it is merely necessary to cut or miter the lower extremity of each of the side strips to 45 degrees, as shown in Fig, 2, in order to secure a perfect t. Thus the side trim strips may be cut to size on any ordinary miter box equipment, having the conventional means for cutting a 45 degree angle.

It i-s thought that the invention `and numerous of its attendant advantages will be understood from the foregoing description and it is obvious that numerous changes may be made in the form, construction and 'arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein described being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. A building construction for supporting a display board or the like, comprising a ground strip defining a wall recess, said ground strip mountingva display board in said recess, peripherally-spaced pressure means interiorly of said recess, and means operatively mounted for movement in the plane of said display board and transversely to the said ground strip and being constrained for shiftable movement in said path to extend across said recess for holding a display board against said pressure means in predetermined relationship thereto.

2. A building construction for supporting a display board or the like comprising a ground strip defining a wall recess, said ground strip having flange portions extending into said recess and permanently mounting yieldable, outwardly-projecting pressure members at spaced, peripheral points, means for retaining a display board positively within said recess andin pressure engagement with said peripheral pressure means, said retaining means comprising a holding member operatively mounted on said ground strip for movement in a fixed predetermined path in the plane of said display board and in a direction transversely of said strip, said hold-A ing member being constrained against movement in all other directions in said path, said hold- Ying member having a portion adapted to extend outwardly from the strip and across the vrecess in one position of the holding member to overlie the outer face of the display board.

3. A building construction for supporting a display board or the like comprising a ground construction dening a wall recess and comprising a plurality of marginally arranged strips, at least one of said strips having an outer portion, guide means associated with the outer portion and extending transversely of said strip, a Aholding member constrained for sliding movement within said guide means in a direction transversely with respect to said strip and having an extension operative in one position to extend across the margin of said recess to retain a display board located therein, and yieldable pressure means within said recess for applying to a display board retained by said keeper means.

4. A construction element comprising an elongated ground strip having an outer surface, a lateral wall associated with said outer surface and supporting an inner flange in spaced, generally parallel relationship to said outer surface, resilient, freely-yieldable pressure means mounted on said liange for applying a yieldable pressure to the inner periphery of a display board, and a laterally extending guideway in association with said outer Wall and extending transversely of the strip substantially in the plane of the outer wall for slidably accommodating a holding member.

5. A construction element comprising an elongated ground strip having an outer surface, a lateral wall associated with said outer surface and supporting an inner flange in spaced, generally parallel relationship to said outer wall, resilient, freely-yieldable pressure means mounted on said flange for applying a yieldable pressure to the inner periphery of a display board, and a lateral guideway in association with said outer wall and extending transversely of the strip substantially in the plane of the outer wall for slidably accommodating a holding member, said guide means and pressure means being disposed in substantially longitudinal alignment along the strip.

l 6. A construction element for use in the assembly of a display board ground comprising an outer wall, an inner wall laterally offset from said outer wall, and means on said inner wall for receiving a pressure spring, said means comprising a tongue laterally offset in a spaced, parallel plane yand providing an aperture in Said inner Wall opposite said tongue for receiving the central portion of' said spring.

7. An elongated construction element for use in the assembly of a display board ground comprising an outer wall, an inner wall laterally offset from said outer Wall, a pressure spring receiving means on said inner wall and comprising a tongue struck out of said wall and laterally disposed in a spaced, parallel plane and providing an aperture in said inner wall opposite said tongue for receiving the central portion of said spring, said struck out portion being integral with said last-named wall adjacent one side edge only whereby a yieldable pressure spring is yieldably disposable within said recess.

8. An elongated construction element for use in the assembly of a display board ground comprising an outer Wall, an inner wall laterally offset from said outer wall, a pressure spring receiving means on said inner wall and comprising a tongue struck out of said wall and laterally disposed in a spaced, parallel plane and providing an aperture in said inner Wall opposite said tongue for receiving the central portion of said spring, and yieldable pressure means comprising a leaf spring having a curved, central portion disposed beneath said struck out portion and extending within said recess, and yieldable extensions projecting outwardly away from said last-named wall and yieldable toward said wall under predetermined pressures, said yieldable extensions being formed to resiliently engage side margins of the tongue to hold the spring in operative position when initially assembled.

9, An elongated construction element for use in the assembly of a display board ground comprising an outer wall, an inner wall laterally oiTset from said outer wall, a pressure spring receiving means on said inner wall and comprising atongue struck out of said wall and laterally disposed in a spaced, parallel plane and providing an aperture in said inner wall opposite said tongue for receiving the central portion of said spring, and a struck out keeper portion formed on said outer wall and integral with said outer wall along longitudinally disposed sides for freely, slidably guiding a latching member in spaced relation to said tongue.

10. A construction element for use in the assembly of a display board ground upon a supporting partition and comprising an elongated, outer Wall adapted to be disposed substantially in the plane of the outer surface of said partition, a marginal attachment iiange inwardly disposed with respect to said outer surface, and a lateral wall joining said attachment flange and outer wall, said lateral Wall being disposed in a plane inclined inwardly of said margin of the outer wall and making an acute angle with said outer wall for interlocking engagement with a plaster coat.

11. A construction element for use in the assembly of a display board ground upon a sup,- porting partition and comprising an elongated, outer wall adapted to be disposed substantially in the plane of the outer surface of said partition, a marginal attachment flange inwardly disposed with respect to said outer surface, and a lateral wall joining said attachment iange and outer wall, said lateral wall being disposed in a plane inclined inwardly of said margin of the` outer wall and making an acute angle with said outer wall for interlocking engagement with a plaster coat, said lateral wall being provided with longitudinally disposed, plaster receiving apertures.

12. A retaining abutment member adapted to positively position a display board with respect to a ground comprising a substantially flat plate vhaving spaced generally .parallel laterali side margins, converging adjacent one extremity to, facilitate entry within a guideway and having lateral projections projecting outwardly of said side margins opposite the other extremity to locate the plate with respect to the guide, and a ground member for attachment to a supporting wall, said ground member having an outer face disposed generally in the plane of said wall and a guideway formed thereon and extending transversely of the ground member in said plane for complementarily receiving the abutment member, said guideway and abutment member being proportioned and arranged to provide a section adapted in one position of the across the .margin thereof to overlie the outer face of an adjacently positioned display board.

13. In combination, an elongated structural element adapted for assembly upon a supporting partition to provide a display board ground, said structural element having an outer wall and extending transversely of said elongated member in the plane of said wall, a guideway on said wall, and a display board retaining member adapted to be slidably received in said guideway, said guideway positively guiding said retaining member in said transverse direction, said retaining member being constrained against movement in all other directions while received by the guideway, said retaining member having a portion adapted to extend outwardly from the strip and beyond a lateral side margin of said outer Wall to overlie the outer face or" a display board.

14. In combination, an elongated structural element adapted for assembly upon a supporting partition to provide display board ground, said structural element having an outer Wall and extending transversely of said elongated member in the plane of said wail, a guideway on said wall, and a display board retaining member adapted to be slidably received in said guideway, said guideway positively guiding said retaining member in said transverse direction, said retaining member being constrained against movement in all other directions while received by the guideway, said retaining member in one slidable position extending substantially beyond the margin of said outer Wall, and a marginal flange substantially inwardly disposed with respect to said outer wall and supporting, yieldable pressure means in juxtaposition to said extremity of said retaining keeper.

15. An elongated construction unit adapted to provide a compound ground structure for supporting a chalk trough in juxtaposition to a trim, said elongated construction element comprising an outer, wall surface arranged in a substantially flat plane, lateral, marginal flange portions disposed longitudinally of said outer, :dat wall surface, and extending on one side, of the plane of said surface, one of said ilanges supporting an attachment flange in spaced relationship to the plane of said outer wall, the other lateral, marginal iiange extending toward but terminating short of the plane of said attachment flange, and apertures in said lateral flanges and aligned in a plane parallel to the plane of said outer wall for receiving a locating pin.

i6. In a display board construction comprising a ground mounted upon a supporting Wall and defining a recess, a display board in said recess, yieldable pressure means peripherally located in sail recess for urging said board outwardly, and a continuous uninterrupted layer of insulating material located between said display board and the supporting partition.y

1'7. A resilient spring clip for releasably securing trim strips to a display board ground construction, comprising a central portion arranged in a laterally curved plane having a convex side and a concave side, said clip terminating in free lateral side margins formed with longitudinally extending bead congurations, said bead configurations projecting` inwardly toward the convex face of said clip for engagement byreversely extending margins of a trim'strip, and means,

being relatively deep, said recesses being spaced so that the upper rib occupiesonly a portion of the depth of the upper recess and provides an additional portion therebelow at least equivalent to the depth of the lower recess, said block being shiftable upwardly with respect to said rail lto a position Where the lower recess is disposed beyond said lower lip and freely disengageable therefrom whereby the block is separable from said lower recess being relatively shallow with 1G said rail.

respect to the lower lip and said upper recess LEON F. URBAIN.

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