PROJECTOR DEVICE WITH LINEAR REFLECTOR

Abstract: In the projector device (50) the projector (10) comprises a light source (14) and a reflector (12). This latter (12) has a surface obtained by causing a suitable plane line to translate such that the surface thus obtained is able to generate a light beam having a substantially rectangular cross section, a dimension of which decreases in receding from the reflector (12) until it becomes reduced to a strip (16), this dimension then increasing on continuing to recede from the reflector (12). Optical devices such as colour filters, colour changer means (20A, 20B, 22A, 22B, 24A, 24B), filters for converting the colour temperature, mechanical dimmers (18) and obscurers can be located at or in the vicinity of that position (16) in which the cross section of the light beam has minimum width. Optical prisms, lenses and diffusers can also be provided. A control unit (52) can also be provided, possibly comprising electronic dimmers, and actuator means (60) for executing the functions of the projector (10) and for moving it.

Description: PROJECTOR DEVICE WITH LINEAR REFLECTOR This invention relates to projectors of the type used to illuminate large buildings, monuments or open-air areas, and in particular to so-called colour changer projectors. Projectors of this type are already known. They comprise a reflector consisting of part of the surface of a solid of revolution obtained by rotating a suitable plane line having a focus. The solids of revolution used are normally ellipsoids or paraboloids. The ellipsoid, obtained by rotating an ellipse about its major axis, is cut with a plane perpendicular to its major axis and is positioned such that the lamp lies at the focus. In this case the luminous flux is concentrated at a point (in reality a small circular area) at the second focus of the ellipsoid, in the vicinity of which smal -dimension coloration or dimming systems can be inserted. As a first approximation the solid of revolution used can also be a spherical mirror (a spherical cap) utilized in an elliptical configuration (ie the lamp is not positioned at the centre of the sphere but at a point coinciding with the ellipsoid to which the spherical cap approximates. With this type of reflector it is not advantageous to use long arc discharge or linear halogen lamps. With the parabolic configuration the lamp is positioned at the focus of the paraboloid and hence the light rays emerge virtually parallel to its axis. Very often (again as a first approximation) a spherical mirror is used but in a parabolic configuration, ie the lamp being positioned at half the radius, so that the 2 behaviour of the spherical cap is equivalent substantially to that of the paraboloid to which it approximates. In this case obviously the area involved is always circular but of considerable dimensions. Consequently small-dimension coloration devices cannot be used. Again, with this type of reflector it is not advantageous to use long arc discharge or linear halogen lamps. Furthermore, because the light sources usable in this type of projector have usually to be of small dimensions, they necessary have a relatively low power. Common linear reflectors are also much used because they enable long arc discharge or linear halogen lamps to be utilized. However in this case the area involved by the luminous flux is rectangular but of large dimensions, hence the coloration systems are complicated, bulky and of low efficiency. The object of this invention is to obviate the aforesaid drawbacks of known colour changer projectors. This object is attained by the projector device of the invention, characterised in that the reflector has a surface obtained by causing a suitable plane line to translate such that the surface thus obtained is able to generate a light beam having a substantially rectangular cross-section, a dimension of this cross-section decreasing in receding from the reflector until it becomes reduced to a strip having a width considerably less than the relative length, this dimension then increasing on continuing to recede from the reflector. Hereinafter the aforedefined reflector will be indicated by the term "linear" reflector and the relative light source by "linear" source (which can consist of a discharge halogen, linear halogen or stroboscopic lamp). The term "linear light source" also means 3 a light source formed from a series of aligned, (theoretically) point-shaped light sources (consisting for example of a series of lamp bulbs arranged as close as possible to each other along a rectilinear path). Preferably the plane line which on translation generates the aforedefined linear reflector surface is a portion of an ellipse or an arc of a circle approximating to an ellipse, although other lines which deviate slightly from the aforesaid lines enable the luminous flux to be concentrated into a strip of sufficiently small width for the aforesaid objects. Inter alia, a broken line consisting for example of rectilinear portions and/or circumferential arcs approximating to the pattern of said ellipse can enable an acceptable result to be obtained (ie of concentrating the luminous flux into a strip of sufficiently small width) . Conveniently the projector of the invention can be completed by a flat or internally concave reflector which closes each of the two ends of the linear reflector, this enabling the end luminous flux (ie that luminous flux which would emerge through the two ends of the linear reflector if it were open) to be recovered. Again conveniently, the linear projector can be provided with an additional linear reflector of circular section positioned on each of the two sides of the main linear reflector, these additional reflectors enabling part of the luminous flux not intercepted by the main linear reflector to be recovered, in particular that part of the luminous flux which is not intercepted by the main linear reflector and which passes close but external to the sides of this latter. The projector of this invention can be of monochromatic type or of the so-called colour changer type, ie provided with a device of known type which can be of greater or lesser complexity and comprise one or more colour filters, but with the significant advantage that the dimensions of the relative filters are 4 extremely small compared with those of the filters of known colour changer projectors, to the extent of being able to be reduced in the limit to the dimensions of said strip into which the light beam can be concentrated. The projector can also be provided with a known colour-subtractive synthesis device, a known filter for converting the colour temperature of the luminous flux, a conventional mechanical dimmer, ie a device consisting of pairs of panels which can be moved towards each other to reduce the luminous flux emerging from the projector, or a conventional optical device comprising filters, diffusers and/or lenses and/or optical prisms. The projector device of the invention can comprise a control unit for the projector operation. The control unit can also be of the type which enables the projector operation to be programmed and can also comprise electronic dimmers, actuator means for executing the various functions and, if the projector is of the moving head type, for driving this latter, and auxiliary remote controls. The invention will be more apparent from the ensuing description of one embodiment thereof. In this description reference is made to the accompanying drawing, on which: Figure 1 is a schematic perspective view of a projector according to the invention; Figure 2 is a generic cross-section therethrough; Figure 3 is a block scheme of the projector device comprising the projector of Figures 1 and 2 and a control unit therefor; Figure 4 shows the pattern of the cross-section of the projector linear reflector when the theoretical elliptical pattern of the reflector is to be approximated by circular arcs; Figure 5 is similar to Figure 4 but with the difference that the theoretical elliptical pattern is approximated by a central circular arc with rectilinear portions towards its ends; Figure 6 is similar to the two preceding figures but with the difference that the theoretical elliptical pattern is approximated 5 by a broken line; and Figure 7 is similar to the three preceding figures but shows a further variant of the reflector profile. As can be seen from Figures 1 and 2, the projector device of the invention can either consist of the projector 10 alone if of the colour changer type, or otherwise comprise this projector. The projector 10 comprises a linear reflector indicated by 12. As can be seen from Figure 2, the plane line used to generate the reflector 12 by translation consists of a part of an ellipse which is symmetrical about the major axis of the ellipse. As can be seen from the figures, a lamp 14, providing a light source of suitable length, is positioned at that of the two foci of the infinite ellipses forming the linear reflector 12 which is closer to this latter. This enables the luminous flux generated by the lamp 14 (which for the purpose of the invention can be considered a linear light source) to be concentrated into a strip 16 of sufficiently small width for the purpose of the invention (in the purely theoretical case of a linear light source acting on an ideal optical device, this width would be zero). A circular arc can be used as a first approximation as the plane line for generating the linear reflector, with the linear light source positioned at a suitable point along the axis of symmetry of the circular arc, intermediate between the centre of the circle and a point distant from the centre of the circle by one half the circle radius, ie coinciding with the focus of the ellipse which is to be approximated. As already stated, reasonable and acceptable results (in terms of the width of the strip into which the luminous flux is concentrated) can also be obtained by approximating said ellipse part by means of several circular arcs (Figure 4) or of rectilinear portions (Figure 6) or of circular arcs and rectilinear portions (Figure 5). Obviously the shorter these rectilinear portions the better the approximation. In practice, shorter rectilinear portions can be used to approximate those curve regions of greater curvature, and longer rectilinear 6 portions for those of lesser curvature. In Figure 4 the theoretical ellipse pattern (for that part of interest to the invention) is approximated by the line 12A formed by three circular arcs, namely the central circular arc 12A.1 and two equal and symmetrical lateral circular arcs 12A.2. In Figure 5 the line 12B which approximates to the theoretical ellipse pattern is obtained by a central circular arc 12B.1 and two equal and symmetrical lateral rectilinear portions 12B.2 and 12B.3. In Figure 6 the line 12C which approximates to the theoretical ellipse pattern is obtained by a broken line formed from a central rectilinear portion 12C.1 and two symmetrical lateral rectilinear portions. In the variant of the invention shown in Figure 7, the projector reflector can have a cross-section formed from portions of different ellipses all however having the same two foci. In this respect, in gradually receding from the axis joining the common foci L and F, the reflector profile 12D continues along ever more internal ellipse portions 12D.2, 12D.3, ...12D.6 having the same foci L and F in common. This enables a reflector (and hence a projector) to be obtained which is of smaller width than the aforedescribed. It is apparent that, by analogous criteria, the aforesaid ellipse portions, if appropriate, could instead of pertaining to ellipses increasingly more inner in receding from the axis LF, pertain to increasingly more outer ellipses, giving however a reflector of greater width. As can be seen from Figures 1 and 2, in the illustrated example the projector 10 is provided with a conventional mechanical dimmer, substantially consisting of two non-transparent panels 18A 7 and 18B which can be moved towards each other to intercept the luminous flux emerging from the reflector 12, to hence reduce the luminous flux until it has been completely obscured. Again from Figures 1 and 2 it can be seen that the projector 10 is also provided with a colour changer device comprising three conventional colour filters each consisting essentially of a pair of flat elements, respectively 20A and 20B of light blue colour (C), 22A and 22B of magenta colour (M), and 24A and 24B of yellow colour (Y), the flat elements of each pair being movable towards each other to increase colour saturation. These three filters enable so-called subtractive synthesis, well known to the expert of the art, to be achieved. It should however be noted that some or all the aforesaid filters can be dispensed with, this depending on the specific requirements and the results to be achieved. Although not included in the case of the projector 10 (for which reason it does not appear in the figure), the projector can also be provided with a conventional filter for converting the colour temperature of the luminous flux. The projector 10 also comprises a conventional optical device (indicated schematically in the figures by a rectangle 26) which can comprise diffusers and/or lenses and/or optical prisms, these elements not being shown as they are well known to the expert of the art. The dimmer 18A, 18B, and the filters 20A and 20B, 22A and 22B, 24A and 24B, including the colour temperature conversion filter (not shown in the figures), are positioned as close as possible to the strip 16 into which the luminous flux is concentrated, this enabling the dimensions of the afore! isted devices to be reduced to a minimum. From Figure 1 it can be seen that at each end of the linear reflector 12 the projector 10 is provided with a flat reflector (but it could also be internally concave, possibly formed from 8 several flat or curved surfaces), 28 and 30 respectively. These two reflectors (which in the illustrated example are slightly diverging) allow recovery of the luminous flux which would otherwise emerge from the two corresponding ends of the linear reflector 12. From Figures 1 and 2 it can be seen that the projector 10 is also provided, along each of the two sides of the reflector 12, with a respective linear reflector 32, 34 of circular cross-section (which could however also be formed from several flat or curved surfaces). The two additional reflectors 32 and 34 enable the luminous flux relative to the angles a1 and a2 to be recovered (Figure 2), and which would otherwise be lost. This invention makes it possible to obtain a high-power projector by virtue of usually using linear light sources (long arc discharge lamps, linear halogen lamps and stroboscopic lamps), which can have very high power, generally greater than point- shaped light sources. In particular, long arc discharge lamps are of relatively low cost and have a very long average life, considerably greater than that of short arc discharge lamps. Moreover the emerging light beam is rectangular, a shape which is normally more suitable for the external illumination of monuments, buildings and the like. Finally, the projector of the invention is provided with very efficient coloration and colour changer devices, mechanical dimmers and obscurers of truly small dimensions. As a ready stated, according to one embodiment of the invention (Figure 3) the projector device 50 can comprise not only the projector 10 but also a control unit 52 for the projector operation. In the illustrated example the unit 52 comprises a control interface 54 connected to a microprocessor 56 for controlling the control members, indicated overall by 58, for operating the stepping motors 60 for executing the various functions and for any required horizontal and/or vertical movement. The unit 52 also comprises a power unit 62 connected 9 (as indicated by the arrow 64) to a source of electricity (such as the electric mains). The unit 52 also comprises a remote control means 66 connected via cables, infrared rays or radio to a reception interface 68 for the signals emitted by the remote control means 66. Consequently the control unit 52 can be remotely operated to program and/or control the switching on and/or off of the projector, its dimming, its colour changes, the changing of the light beam dimensions and its horizontal and/or vertical movement.

Claims: 10 Cl ai ms : 1. A projector device (50) in which the projector (10) comprises a light source (14) and a reflector (12), characterised in that the reflector (12) has a surface obtained by causing a suitable plane line to translate such that the surface thus obtained is able to generate a light beam having a substantially rectangular cross-section, a dimension of this cross-section decreasing in receding from the reflector (12) until it becomes reduced to a strip (16) having a width considerably less than the relative length, this dimension then increasing on continuing to recede from the reflector (12). 2. A projector device (50) as claimed in claim 1, wherein the plane line which on being translated generates the surface of the reflector (12) is a portion of an ellipse (12) or of a line (12A, 12B, 12C) which approximates to an ellipse, said portion being symmetrical about the ellipse axis, the linear light source (14) being located at that ellipse focus positioned closer to the reflector (12). 3. A projector device as claimed in claim 2, wherein the line which approximates to an ellipse is a broken line (12B; 12C). 4. A projector device as claimed in claim 3, wherein the broken line (12B) is formed from rectilinear portions (12B.2, 12B.3) and/or curvilinear portions (12A; 12B.1). 5. A projector device as claimed in claim 4, wherein the broken line portions (12C) are rectilinear and have a greater length in those regions in which the ellipse portion which is approximated has lesser curvature, and vice versa. 6. A projector device as claimed in claim 1, wherein the plane line (12D) which on being translated generates the surface of the reflector (12) comprises portions of different ellipses, all however having the same two foci (L and F), the portions of 11 said plane line (12D), in gradually receding from the axis joining the common foci L and F, pertaining to gradually more inner or more outer ellipses. 7. A projector device (50) as claimed in claim 1, wherein the projector (10) also comprises a flat or internally concave reflector (28, 30) which closes each of the two ends of the linear reflector (12). 8. A projector device (50) as claimed in claim 1, wherein the projector (10) also comprises an additional linear reflector (32, 34) of circular cross-section formed from several flat or curved surfaces, and located on each of the two sides of the main linear reflector (12) to recover part of the luminous flux not intercepted by the main linear reflector (12). 9. A projector device (50) as claimed in claim 1, wherein the projector (10) comprises colour filters (20, 22, 24) located at or in the vicinity of that position (16) in which the cross-section of the light beam has minimum width. 10. A projector device (50) as claimed in claim 1, wherein the projector (10) comprises a colour changer device (20A, 20B, 22A, 22B, 24A, 24B) of colour-subtractive synthesis type located at or in the vicinity of that cross-section position (16) in which the light beam has minimum width. 11. A projector device (50) as claimed in claim 10, wherein the colour changer device of the projector (10) comprises three colour filters (20A, 20B, 22A, 22B, 24A, 24B), each comprising a pair of flat elements, of light blue, magenta and yellow colour respectively, which can be moved towards each other to increase colour saturation. 12. A projector device (50) as claimed in claim 1, comprising a filter for converting the colour temperature of the luminous flux, located at or in the vicinity of that cross-section position 12 in which the light beam has minimum width. 13. A projector device (50) as claimed in claim 1, wherein the projector (10) comprises a mechanical dimmer (18) for varying the luminous flux emerging from the projector (10), the dimmer being located at or in the vicinity of that position (16) in which the cross-section of the light beam has minimum width. 14. A projector device (50) as claimed in claim 13, wherein the mechanical dimmer of the ellipse (10) comprises two non- transparent panels (18A, 18B) which can be moved towards each other to intercept the luminous flux emerging from the reflector (12) in order to reduce the luminous flux until it has been completely obscured. 15. A projector device (50) as claimed in claim 1, wherein additional filters, diffusers and/or optical elements and/or prisms are provided in the projector (10). 16. A projector device (50) as claimed in claim 1, comprising a possibly programmable control unit (52) for the operation of the projector (10). 17. A projector device (50) as claimed in claim 16, wherein the control unit (52) comprises a control interface (54) connected to a microprocessor (56) for controlling the driver circuits (58) of the stepping motors (60) for executing the functions and the movement of the projector (10). 18. A projector device as claimed in claim 16, wherein the control unit (52) comprises electronic circuits for regulating the electric power to the lamp (14). 19. A projector device (50) as claimed in claim 16, wherein the control unit (52) comprises a remote control means (66) connected to a reception interface (68) for the signals emitted by the remote control means (66).

Inventors: BERTINI FRANCO, BERTINI, FRANCO
Applicants: BERTINI FRANCO, STUDIO DUE LIGHT DIVISION S R, BERTINI, FRANCO, STUDIO DUE LIGHT DIVISION S.R.L.
Application year: 1998
Main classification: F21P3
IPC codes: F21S10, F21V7, F21V9, F21V13, F21V23