BACKGROUND OF THE INVENTION
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Conventional easels usually comprise a tripod or similar arrangement of legs comprised of telescoped tubes or foldable struts which may be extended linearly to a desired height and which have a display support platform across one or more of the tubes or struts. The tubes or struts are usually held in extended position by means of a thumb or set screw or screw collar or similar fastening means locking one tube or strut to the adjacent tube or strut. To collapse the tubes or struts, the thumb screw or screw collar is turned-and one tube is telescoped into an adjacent tube, or the struts are pivotally folded together. Likewise, the display platform may be adjustable along the tubes or struts and conventionally secured at a desired height by conventional fastening means. Frequently, it is necessary to remove the display support platform from the legs or to fold this support or move the support out of its desired display supporting position when collapsing the easel legs, and to reverse the procedure when setting up the easel. Often the display-supporting platform must be moved to a selected height when the easel is again set up for use. To adjust the angle between the front face of the easel and ground all the three legs of the conventional collapsed easel must be readjust the heights. It is purpose of the current application to provide an easel that is easy to adjust the angle between the front canvas mounting face and the ground.
DESCRIPTION OF THE PRIOR ARTS
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U.S. Pat. No. 6,820,844 to Tiffen, et al. illustrates a miniature tripod is mounted in a hollow handle of a main tripod for joint use therewith for increased versatility, as well as for removal therefrom for individual use.
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U.S. Pat. No. 6,305,653 to Oldham, et al. illustrates a portable tripod support beneath a portable notebook computer for a seated computer user. The support comprises a platform with spider-like foldable support arms having relatively folded parallel and unfolded flat coplanar positions.
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U.S. Pat. No. 6,202,974 to Rellinger illustrates a portable easel with adjustable board support which has a plurality of legs pivotally joined together by a head, the legs of which may be selectively spread apart when set up as an easel and folded together when collapsed, each leg composed of multiple interlocked sections biased together when in extended position but which may be manipulated for separation and folding into a bundle one section against another section for storage and transport, and a board support mounted on at least one leg which may be selectively adjustably moved to a desired position on any of the sections and moved against the leg on which it is mounted for storage and transport and extended away from the leg for holding a display on the easel when set up.
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U.S. Pat. No. 6,135,413 to Glebe illustrates a tripod easel support device comprising a pair of relatively inwardly inclining bracing elements each joined together at one end at an apex, the apex including a leg-receiving recessed portion conforming to the rear leg profile to receive the rear leg of a tripod easel and further having a pair of inwardly projecting detent surfaces formed to project inwardly of the side surfaces of the rear leg to retain the leg within the recess.
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U.S. Pat. No. 4,609,174 to Nakatani illustrates a folding easel that has three telescoping legs, leg locks for locking each of the legs at arbitrarily extended positions, two tie-bars each hinged at one end to an axle supported on a corresponding leg lock, one tie-bar being snap-engageable to an axle on a third leg lock, the remaining tie-bar being snap-engageable to an intermediate point of the first tie-bar to form a T tie-bar arrangement for maintaining the three legs in fixed spaced apart relationship and usable as a shelf for paint boxes or the like, the tie-bars being readily disengageable without removal of fasteners for folding together of the three.
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U.S. Pat. No. 4,196,881 to Davidson illustrates an improved tripod mount for cameras or the like and embodying the feature of simplified raised or lowered adjustment of camera height, as well as the feature of adjustably spreading and/or collapsing the legs in a single unitary motion which can add the convenience of floor rollability when desired.
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U.S. Pat. No. 4,171,116 to Carver, et al. illustrates an adjustable and collapsible easel having a plurality inner and outer telescoping leg sections. The upper ends of the outer leg sections are connected to a common connecting member for articulated movement between fully spread and fully folded positions. The outer ends of a plurality of foldable brace members are connected to respective ones of the outer leg sections and the inner ends of the brace members are connected to a common fitting. The brace members reinforce and hold the legs in an operative, spread position.
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None of the prior art illustrates an easel that leans back wards to adjust the angle between the front mooting surface and the ground.
SUMMARY OF THE INVENTION
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A portable easel with adjustable board support angle to the ground is provided. Three sets of telescopic legs are pivotally connected together at one head of an isosceles triangular shape. The isosceles triangular head has one long side and two short sides. Two legs are connected to the long side of the head forming a straight line when stretched. One crossing bar, upwardly folding in the middle thereof, connects the two front legs and determines the maximum angle between the two front legs. One leg, rear leg, is connected to the rear angle point of the isosceles triangular head. One end of a telescopic connector is pivotally connected to the rear leg and the other end thereof is connected to a pivotal connector that receives the upwardly folding crossing bar. The pivotal connector is engaged to a rail that is fixed to the triangular head vertically between the two front legs. A horizontal platform for supporting a canvas or the like is engaged to the rail to move up and downward smoothly. By adjusting the length of the telescopic connector, the angle of the front surface of the easel, which is formed by the two front legs, to the ground is adjusted.
BRIEF DESCRIPTION OF THE DRAWINGS
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FIG. 1 is a perspective view of the easel of the first embodiment of the current application showing the easel as it is being set up by unfolding of its sections.
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FIG. 2 is a perspective view of the easel of the second embodiment of the current application showing the easel as it is being set up by unfolding of its sections.
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FIG. 3 is a perspective view of the easel of the current application showing how the easel is folded.
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FIG. 4-a is a detailed view showing the interlocking mechanism of the telescopic clamp marked as ‘A’ in FIG. 1 and FIG. 2 when the clamp is released.
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FIG. 4-b is a detailed view showing the interlocking mechanism of the telescopic clamp marked as ‘A’ in FIG. 1 and FIG. 2 when the clamp is locked.
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FIG. 5 is an exploded view of connecting mechanism of the rail and canvas supporting platform.
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FIG. 6 is a schematic drawing showing relative size of the rail groove and the washer pin.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
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With reference to the accompanying drawings, and particularly to FIGS. 1, the portable easel (100) with its adjustable board support (124) embodying the present invention comprises an isosceles triangular tripod head (101) which has one long front side (101-1) and two short sides (101-2) and (101-3). Among three telescopic legs (112, 113, and 114), two legs (112) and (113) are connected to the front side (101-1) to form a planar front face (101-4). One leg, rear leg (114), is connected to the rear angle point (1014) of the isosceles triangular head.
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The two legs (112) and (113) are connected each other via a slide (133) and two links (128) and (129). The slide (133) moves upward along a rail (122) that is fixed to the inside of the long front side (101-1) of the triangular tripod head (101). Three links of (128), (129) and (130) are pivotally connected to the slide (133). The two legs (122), (113), the two links (128), (129), the slide (133) and the rail (122) are aligned on the front face (101-4).
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A link (130) connects the rear leg (114) to the slide (133). That link (130) is telescopically foldable and is comprised of clamp (132) and two square pipe (131) and (131-1) of different size. Square pipe (131) is smaller one and (131-1) is a larger one. By adjusting the relative position of the two square pipes of (131) and (131-1), a user can adjust the angle between the front face (101-4) and the ground. A canvas support (124) is slidably engaged to the rail (122) via a nut (135). The rest part of the telescopic legs (116), (116′), (117), (117′), (118), (118′) are connected to the legs (112), (113), and (114) via clamps of (119), (119′), (120), (120′) and (121), (121′) respectively.
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FIG. 2 is a perspective view of the easel of the second embodiment of the current application showing the easel as it is being set up by unfolding of its sections. The second embodiment has additional clamps (280) and (281) on the links of (228) and (229) which connects the two front legs (213) and (212). These additional clamps (280) and (281) allow a user to adjust the angle between the rail (122) and the ground along the front face (101-4).
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FIG. 3 is a perspective view of the easel of the current application showing how the easel (100) is folded. As the slide (133) moves up along the trail (122), the links (128), (129), and (130) draw the three legs (122), (113) and (114) close to the rail (122). After the three legs are (112), (113), and (114) are folded, the canvas support (124) is rotated to parallel to the rail (122) by releasing and fastening the nut (135). Then the easel becomes compact.
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FIG. 4-a and FIG. 4-b are detailed view showing the interlocking mechanism of the telescopic clamp (132) and (232) marked as ‘A’ in FIG. 1 and FIG. 2. When the clamp (132) is positioned in a released mode, a big hump side (132-a) of the clamp (132) is exposed to the outer side of the square pipes (131) and (131-1). And there is a gap between the inner surface of the smaller square pipe (131) and a smaller hump (132-b) as show in FIG. 4-a. Then, the two square pipes (131) and (131-1) moves freely along each other.
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When a position is selected, turn the clamp (132) to the other end. Then the big hump (132-a) meets the inner surface of the smaller square pipe (131) and fix the relative positions of the two pipes(131) and (131-1).
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FIG. 5 is an exploded view of connecting mechanism of the rail (122) and a canvas supporting platform (124).A screw bolt (137) is engaged in a groove (122-1) of the rail (122). The screw bolt (137) moves along the groove (122-1) inside thereof. A canvas support (124) is engaged to the bolt (137) through a bolt hole (138). A washer pin (136) is engaged to the bolt (137) through a hole (136-1) and to the canvas support (124) through two slits (139). Finally, a nut (135) is coupled to the bolt (137).
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FIG. 6 is a schematic drawing showing relative size of the rail groove (122-1) and the washer pin (136). The width of the washer pin (136) is slightly narrower than that of the groove.
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Due to the shape of the washer pin (136), position of the two slits (139) on the canvas support, and the groove (122-1) on the rail (122), the canvas support (124) can be positioned rectangular to the rail and parallel to the horizontal ground. By the mechanism described above, the easel of the current application can provide an easel that can adjust the angle between the front face, a canvas is placed thereon, and the ground by simply adjust the length of the rear link. A canvas is placed in a horizontal position by adjusting the length of the side links that are introduced in the second embodiment of the current application.
