Device for moving the luminous beam in a projector, in particular a medium or high-powered projector

Abstract: The invention regards a device for moving the luminous beam in a projector; to be included are a hollow shaft (10) secured to the support platform (3) in such as way as to rotate around a first axis (A); the projector body (2) is secured to the shaft (10) in such a way as to rotate relative to this shaft around a second axis (B) that is slanted with respect to axis (A); inside the shaft (10) there is an articulated transmission shaft (20), whose lower end is secured to the support platform (3) and the upper end is secured to the projector body (2).

Description: This present invention regards projectors with a mobile luminous beam on a conical surface, in particular medium and high-powered projectors, which are used, typically but not exclusively, for outdoor advertising or for special effects for discotheques, large concerts, fairs, special events, etc. The aforesaid projectors, single or grouped on a single support platform, include substantially one or more projector bodies that rotate, supported by the platform. The projector body holds the light source and all the necessary elements and accessories for creating the desired luminous beam; for example, the lamp, the lamp-holder element, the parabolic mirror, any cooling devices, the electrical terminal boards, etc. The high-intensity luminous beam is made to rotate around the sky in such a way that its axis goes along a conical surface whose top angle is more or less wide. To obtain this, a curved shaft is currently used that is pivoted to the support platform, and this shaft rotates around a fixed axis that is generally vertical or almost vertical. The projector body, in its turn, is pivoted to the upper end of the curved shaft with the axis in slanted rotation with respect to the first axis; special cylindrical springs connect the projector body to the platform in such a way as to obtain, during the rotation of the curved shaft around the first axis, the simultaneous rotation in the opposite direction of the projector body with respect to the curved shaft so that the projector body, though rotating its own luminous beam, substantially maintains the same orientation, and this because the presence of the electrical supply cables connected to the projector body prevents it from rotating around its own axis. A device of such kind is shown in the patent document US-A-4298911. This technique still presents certain drawbacks that are mainly connected to the presence of the aforesaid springs. These springs, in fact, during rotation, are periodically strained, and this leads to greater strain on the structure of the support and rotation device and more effort needed for effecting the rotation, especially in the case of a group that includes several projector bodies that rotate simultaneously and that simultaneously put a strain on the springs. Consequently, a larger and sturdier structure is necessary as well as a more powerful motor for rotation, and energy consumption is greater. In addition, after much use the springs are subject to breaking with the consequent jolting of the projector body, blows, and possible breakage of the supply cable. The purpose of this present invention is to create a device that is able to make the luminous beam rotate in such a way as to overcome the above-mentioned drawbacks. This purpose is achieved by the invention in question as characterised in the way described in the patent claims. Thanks to this invention, the projector body moves without any particular strain that is not caused by the normal (and insignificant) friction from the bearings. It is thus sufficient to have a less powerful motor, and the structure of the device itself can be less sturdy and heavy. In addition, there are no risks of breakage that could cause the projector body to rotate freely with respect to the shaft that supports it. The invention is described in detail in the following paragraphs, with the aid of the enclosed drawings that illustrate one way to put it into operation. FIG. 1 is a schematic side view of a group of two projectors, both equipped with the device in question, situated on the same support platform. FIG. 2 is an enlarged and partially sectioned detail of FIG. 1, illustrating the device in question. With reference to FIG. 1, each projector includes a projector body 2 of the normal type, that is used to form a luminous beam whose axis is indicated by the letter L. Inside the box that covers the projector body 2 are placed: the lamp that supplies the light source, supported by a lamp-holder element, any lamp cooling means, the parabolic mirror that projects the light within a limited beam, the electrical terminal boards, and all the other normal elements for an apparatus of this type; all of the aforesaid elements are no further illustrated or described in that they are of the usual type. The projector body is supported by a support platform, indicated in all the drawings by the number 3, in which are located the switches for turning the projectors and other elements on. A power supply cable 4 connects the projector body 2 with the platform 3 which is in its turn connected to electrical equipment (not shown) for control and transformation of the electrical current. The device in question includes a rigid hollow shaft 10, secured to the platform 3 in such a way as to be able to rotate around a first fixed axis A. The projector body 2 is secured to the shaft 10 in such a way as to rotate with the shaft around axis A and simultaneously be able to rotate in relation to the shaft around a second axis B which is slanted with respect to axis A. Inside the shaft 10 are fitted the means 20 that are able to transmit the rotary motion around at least two axes slanted to each other. The aftoresaid means 20 are fitted with their axes substantially coinciding with rotating axes A and B; in addition, the lower end of the means 20 is torsionally secured to platform 3 and the upper end is torsionally secured to projector body 2. Other means 40 are included, which are capable of making shaft 10 rotate around axis A. The rotation of shaft 10 produces the simultaneous rotation of axis B, around axis A, which defines a conical surface whose conicity is determined by the angle between axes A and B. Simultaneously, the means 20 keep the body 2 constantly oriented, regarding the rotation around axis A (thus there is a rotation of body 2 with respect to shaft 10, around axis B, equal and opposite to the rotation of shaft 10 around axis A) as is necessary because of the presence of cable 4. The result is that axis L of the luminous beam produced rotates, defining a conical surface that can coincide or differ from the surface defined by axis B; if, for example, axis L coincides substantially with axis B, the two conical surfaces coincide, otherwise they are different. According to the way of putting into operation shown, shaft 10 includes a lower portion 11 that is coaxial with axis A, and an upper portion 12 coaxial with axis B. The means 20 include a first shaft 21 that is coaxial with axis A, solidly bound to the support platform; in detail, shaft 21 fixed into a body 31 that is solidly bound to platform 3. The means 20 also include a second shaft 22, coaxial with axis B, jointly secured to the projector body 2; in detail, shaft 21 is fixed onto a bracket 32 which supports the base of projector body 2, and the screw-locking elements 33 (of the usual type) tighten body 32 onto the upper end of shaft 22. An articulated coupling joint 23, for example a Cardan joint, as shown in FIG. 2, connects the near ends of the two shafts 21 and 22. The lower portion 11 of shaft 10 is connected to shaft 21 in such a way as to form a pin-bearing assembly with this shaft; in the same way, the upper portion 12 is connected to shaft 22 in such a way as to form a pin-bearing assembly with this shaft. In detail, the two portions 11 and 12 are coupled to the respective shafts 21 and 22 by means of suitable pairs of rolling bearings 25 placed between a respective bushing 26, jointly secured to portion 11 and 12 respectively, and shaft 21 and shaft 22 respectively. The means 40 include a gear wheel 41 secured coaxially to the lower portion 11 and connected, using a drive chain 42, to a second gear wheel 43 made to rotate by a geared motor (not shown). The means 40 are housed under a box 34 that covers platform 3. The entire shaft 10 is put into rotation around axis A by means of wheel 41; in the meantime, the articulated shafts 21 and 22 keep body 32 secured, with respect to the rotation around axis A, to platform 3; at the same time, shaft 22 can move with its own axis B which completes one rotation around axis A. Obviously, numerous application variations can be applied to the invention in question; for example, the means 20 can be replaced by other equivalent means, without going away from the invention as described in the patent claims.

Claims: Device for moving the luminous beam in a projector, in particular in a medium or high-powered projector, including a projector body (2) able to supply a luminous beam sustained by a support platform (3) comprising a rigid shaft (10) secured to the support platform (3) in such a way as to be able to rotate around a first axis (A), the aforesaid projector body (2) being secured to the aforesaid shaft (10) in such a way as to rotate jointly with this shaft (10) around aforesaid axis (A) and simultaneously being able to rotate, relative to this shaft (10), around a second axis (B) that is slanted with respect to the first axis (A); characterized in that it comprises means (20) that are able to transmit the rotary motion around at least two axes slanted to each other, aforesaid means of transmission (20), being fitted inside the rigid shaft (10) with its own axes substantially coinciding with aforesaid rotation axes (A) and (B), the lower end of aforesaid means of transmission (20) being torsionally secured to the support platform (3) and the upper end being torsionally secured to the projector body (2), the rigid shaft (10) being a hollow shaft. Device as claimed in claim 1, characterised by the fact that aforesaid hollow shaft (10) includes a lower portion (11) that is coaxial with aforesaid first rotation axis (A) and an upper portion (12) that is coaxial with aforesaid second rotation axis (B). Device as claimed in claim 2, characterised by the fact that aforesaid means (20) of drive transmission include: a first shaft (21) that is coaxial with aforesaid first rotation axis (A), integrally secured to the support platform (3); a second shaft (22) that is coaxial with aforesaid second rotation axis (B), integrally secured to the projector body (2); an articulated coupling joint (23) that connects the aforesaid first and second shafts (21) and (22); the lower portion (11) of the hollow shaft (10) being connected to aforesaid first shaft (21) in such a way as to define a pin-bearing assembly; the upper portion (12) of the hollow shaft (10) being connected to aforesaid second shaft (22) in such a way as to define a pin-bearing assembly.

Inventors: BRUNO BAIARDI C O SPACE CANNON, RENATO PAROLA C O SPACE CANNON, BRUNO, BAIARDI, C/O SPACE CANNON VH S.R.L., RENATO, PAROLA, C/O SPACE CANNON VH S.R.L.
Applicants: SPACE CANNON VH SRL, SPACE CANNON VH S.R.L.
Application year: 1991
Main classification: F21P3
IPC codes: F21S10, F21V21