Display apparatus

Abstract: Display apparatus comprises an inner picture frame (2) supported by magnetic means within an outer frame (1). The magnetic means uses a solenoid coil (3) operatively associated with magnet (5) and controlled through a position sensor (4) with permanent stabilising magnets (6) and (10). Impulse generating means comprising sensor (9) electromagnet (8) and magnet (7) effect rotation of the frame (2) by application of periodic magnetic force induced by the pulses. The apparatus is used to display pictures, art work or objects.

Description: This invention relates to display apparatus and is primarily, but not essentially, concerned with an apparatus for displaying printed matter particularly art work. In GB 2217503 a photograph frame in the form of a cube is magnetically attracted upwards and stabilised by a filament connecting the frame to a base. The frame is not truly freely suspended nor stabilised and in particular the frame cannot be rotated to an unlimited extent by virtue of the filament forming a tether. GB 2107085 describes a means for suspending a sphere using magnetic means but the disclosure does not reveal any means for controlled rotation. An object of this invention is to provide an apparatus for holding or framing art work in free suspension to allow unlimited rotation under control. In accordance with this invention there is provided a display apparatus comprising a stationary part and a freely movable floating part which is supported by magnetic means relative to the stationary part and spatially positioned using control means to detect the relative positions of the parts and to effect control of the magnetic means to maintain a predefined spacing between the parts, the apparatus being characterised by the stationery part comprising an outer frame member and the floating part comprising an inner frame member adapted to receive art work or the like, cooperating magnetic means being provided in the outer and inner frame members whereby the inner frame member is held suspended relative to and within the confines of the outer frame member by such magnetic means the apparatus being further characterised by a means to impart a rotational force to the inner frame member. The apparatus preferably includes means to impart a steady controlled rotation to the inner frame advantageously using magnetic means and more particularly by impulse-wise energy to maintain steady rotation. In a preferred construction the outer frame has at least a U-shaped form with opposed and spaced sides between which the inner frame member is suspended by the magnetic means. As will be appreciated, the inner frame is supported and suspended without mechanical connection and by virtue of such suspension it is free to rotate, preferably about a vertical axis. This construction would enable the inner frame to have two or more sides which can be viewed by rotating same either through application of mechanical or manual force or by applying an electromagnetic rotational component of force between the two frames preferably by using pulsed means. In a particular realisation of the invention the inner frame includes a permanent magnet mounted on a top part and centrally which cooperates with an electromagnetic means mounted in a central top part of the outer fixed frame. The magnet in the fixed frame would be arranged at the centre of gravity which may or may not coincide with the geometric centre. Control means are included together with a sensor whereby a substantially constant spacing is maintained between the cooperating electromagnetic means on the outer frame and the permanent magnet on the inner frame. The position sensor is preferably mounted in a lower part of the fixed frame coincident with the vertical axis through the electromagnetic means and the permanent magnet. Control means provides appropriate adjustment to the electromagnetic means in order to maintain the inner frame suspended in a fixed position. The outer frame may comprise a generally rectangular structure formed by spaced top and bottom horizontal members supported by side frame members or columns. The base may include the sensor and control means and forms a frame for standing on a support surface. A power supply means may be provided in the base of the outer frame and this may be connected through a lead to a suitable power source. In one construction a permanent magnet is mounted on the top of the inner picture frame such that the centre of the magnet coincides with a vertical axis through the centre of gravity of the picture frame. The picture frame is positioned within an outer fixed framework. An electromagnet is mounted on the top of the fixed framework such that the centre of the electromagnet coincides with the vertical axis. To achieve nearly periodic rotation of the picture frame, an additional set of electromagnets on the outer fixed frame and an additional permanent magnet on the picture frame is employed. The invention will be described further and better understood from the following description when read in conjunction with the accompanying drawings, which show embodiments by way of examples only. In the drawings:- Figure 1 shows a schematic diagram of a display apparatus, Figure 2 shows a block diagram of the electronic control means, and Figures 3 and 4 show two constructions according to this invention. Referring to the drawings, Figure 1 illustrates the display apparatus which comprises an outer fixed frame (1) wherein the picture frame (2) levitates and rotates. A permanent magnet (5) is mounted on the top part of the picture frame (2) such that the centre of the permanent magnet (5) coincides with a vertical axis through the centre of gravity of the picture frame (2). A solenoidal electromagnet (3) is mounted on the top part of the outer fixed frame (1) such that its centre also coincides with the vertical axis. A position sensor (4) consisting of a coil and a permanent magnet at the bottom of the outer fixed frame (1) detects the levitating position of the picture (2) and provides an electrical feedback to a proportional and integral servo-controller that regulates a MOSFET amplifier supplying current to the electromagnet (3). The centre of the position sensor (4) coincides with the vertical axis. A permanent magnet (6) is mounted in the bottom part of the picture frame (2) such that its centre coincides with the vertical axis to trigger the position sensor (4). The permanent magnet (10) inside the position sensor (4) improves the stability of levitation. The gap between the electromagnet (3) and the permanent magnet (5) on top of the picture frame is a stable but adjustable value between 0.5 cm and 2.5 cm. The position sensor (4) may alternatively be an infrared sensor responsive to radiation for emitters reflected from the picture frame and mounted at the top or bottom of the outer fixed frame. The position sensor (4) may also alternatively be a Hall effect semiconductor chip in place of the coil at the bottom. The picture frame (2) may also be made to rotate nearly periodically about the vertical axis through the centre of gravity. For this purpose, a permanent magnet (7) is mounted on one of the sides of the picture frame (2). An electromagnet (8) and a magnetic sensor switch (9) are mounted on the outer fixed frame (1) at a position opposing the side mounted permanent magnet (7). The magnetic sensor switch (9) detects the rotational movement of the picture frame and activates the electromagnet (8) with a repulsive impulse that kicks on the side mounted permanent magnet (7). Depending on the shape of picture frame (2) there may be more than one position opposing the electromagnet (8) and the sensor switch. Hence a plurality of permanent magnets may be similarly installed on the picture frame (2). The direction and rate of rotation may be adjusted for visual presentation between 5 sec per revolution and 30 sec per revolution by known electronic control mechanisms (11), such as a synchro-drive controller. The picture frame (2) may also be used as a multi-purpose display frame. The photograph or print may be replaced by other small objects. The shape of the picture frame may be adjusted to hold such small objects, otherwise the construction of the multi-purpose display frame remains identical to the picture frame (2). It is even conceivable for an actual article itself to have embedded therein an appropriate magnet whereby the article is suspended and comprises itself the inner frame. Figure 2 of the drawings illustrates schematically the electronic control circuit having a power supply 20 which could be a battery or mains driven supply which leads the servo-controller 21 to which is connected the position sensor 4 and amplifier 22 which controls the power fed to the electromagnet 3. In addition and also connected to the power supply 20, is the rotational drive controller 23 which feeds appropriate impulses to the electromagnet 8 to achieve rotation and is in turn synchronised by the magnetic sensor switch 9. Figures 3 and 4 of the drawings show two practical constructions of the invention and in Figure 3 the outer frame comprises a base 30 which houses the power supply 20 together with the electronic control circuitry shown in Figure 2 which has two vertical columns 31, 32 which support a top frame member 33. The top frame member 33 includes a housing 34 which contains the electromagnet 3 and the base member 30 has a housing 35 which contains the sensor and stabilising magnet 4 and 10. In this example the inner frame 2 has a conventional picture frame construction which is capable of supporting two items of art work 36 in back to back relationship. The construction shown in Figure 4 is of generally similar design but here the outer frame 1 is more in the nature of a window and like parts have the same references as in Figure 3.

Claims: A display apparatus comprising a stationary part and a freely movable floating part which is supported by magnetic means relative to the stationary part and spatially positioned using control means to detect the relative positions of the parts and to effect control of the magnetic means to maintain a predefined spacing between the parts, the apparatus being characterised by the stationery part comprising an outer frame (1) member and the floating part comprising an inner frame member (2) adapted to receive art work or the like, cooperating magnetic means (3,5) being provided in the outer and inner frame members whereby the inner frame member is held suspended relative to and within the confines of the outer frame member by such magnetic means the apparatus being further characterised by a means (8,9) to impart a rotational force to the inner frame member (2). Display apparatus according to Claim 1, charaterised in that the outer frame (1) has at least a U-shaped form with opposed and spaced sides (31,32) between which the inner frame member (2) is suspended by the magnetic means (3,5,34). Display apparatus according to Claim 1 or 2, characterised in that the inner frame (2) includes a permanent magnet (5) mounted on a top part and centrally and which cooperates with an electromagnetic means (3) mounted in a central top part of the outer fixed frame (1). Display apparatus according to Claim 3, characterised in that control means (21,22,23) are included together with a sensor (4) whereby a substantially constant spacing is maintained between the cooperating electromagnetic means (3) on the outer frame (1) and the permanent magnet (5) on the inner frame (2), by controlling the electromagnetic means (3). Display apparatus according to Claim 4, characterised in that the position sensor (4) is mounted in a lower part (11) of the fixed frame (1) coincident with the vertical axis through the electromagnetic means (3) and the permanent magnet (5), the sensor comprising a magnetic, optical, infra-red or Hall effect device. Display apparatus according to Claim 4 or 5, characterised in that the outer frame (1) comprises a generally rectangular structure formed by spaced top (33) and bottom (30) horizontal members supported by side frame members or columns (31,32). Display apparatus according to Claim 6, characterised in that the bottom horizontal member (30) comprises a base which includes the sensor (4) and control means (21,22,23) and forms a frame for standing on a support surface with a power supply means (20) provided in the base (30) of the outer frame (1) connected through a lead to a suitable power source. Display apparatus according to any preceding claim charaterised in that a permanent magnet (5) is mounted on the top of the inner picture frame (2) such that the centre of the magnet coincides with a vertical axis through the centre of gravity of the picture frame, the picture frame being positioned within an outer fixed framework (1) with an electromagnet (3) mounted on the top of the fixed framework such that the centre of the electromagnet coincides with the vertical axis Display apparatus according to any preceding claim characterised in that the means to impart a rotational force to the inner frame (1) is a magnetic means (8,9), said means preferably operating pulse-wise to impart a steady rotation. Display apparatus according to any preceding Claim 3 to 9, chacaterised in that an air gap is provided between the top mounted electromagnet (3) of the outer fixed frame (1) and the top mounted permanent magnet (5) of the picture frame (2) of between 0.5cm to 2.5cm. Display apparatus in accordance with any preceding claim, characterised by:- a permanent magnet (7) mounted on one of the sides of the inner frame (2) and an electromagnet (8) with a magnetic sensor (9) mounted on the outer fixed frame (1) at a position opposing the said side mounted permanent magnet (17) and supplying an impulse to sustain rotation of the inner frame. Display apparatus according to Claim 11 charaterised in that a sensor with a servo-control and feedback circuit is provided in the outer frame (1) to control the direction and rate of rotation to between 5 seconds per revolution and 30 seconds per revolution. Display apparatus according to Claim 11 or 12, charaterised in that a plurality of permanent magnets (7) are mounted on the sides of the picture frame (2) opposing the electromagnet (8) mounted on the outer fixed frame (1). Display apparatus according to any preceding Claim 3 to 13 charaterised in that stabilising cooperating magnetic means (6,10) are provided on the bottom of the inner frame (2) and the bottom of the outer frame (1).

Inventors: TANG SING HAI, TANG, SING HAI
Applicants: TANG SING HAI, TANG, SING HAI
Application year: 1996
Main classification: G09F19
IPC codes: G09F19