IT201800005392A1 - PROJECTOR - Google Patents

Description

DESCRIPTION

of the patent for industrial invention entitled:

"PROJECTOR"

TECHNIQUE SECTOR

The present invention relates to a projector, preferably for stage.

ANTERIOR ART

In the entertainment sector, projectors configured to obtain scenic effects through light beams are known. Projectors of this type are generally used in professional environments such as theaters, television studios, discos, stages for live events, shopping centers and much more.

A typical stage projector comprises at least one lighting device and an optical output element arranged in a casing.

In recent years there has been a significant increase in the use of lighting devices with LED type light sources.

The LEDs most used in projectors are white LEDs as they allow the creation of stage projectors with limited dimensions and high efficiency in terms of brightness.

In projectors of this type, color filters are used to obtain beams having colors other than white.

Projectors with color LEDs are less common. This mainly depends on the fact that, with color LEDs, it is necessary to adopt complex optical solutions in order to obtain a uniformity of colors suitable for market demands. However, these complex optical solutions lead to a lowering of the luminous flux and efficiency of the projector.

DESCRIPTION OF THE INVENTION

The purpose of the present invention is to provide a projector, preferably for stage, which is easy and economical to manufacture and which can also be equipped with color LEDs without affecting the quality and intensity of the emitted light beam.

In accordance with this purpose, the present invention relates to a projector, preferably for stage, comprising a source unit configured to emit one or more light beams along an emission direction; a reflector element configured to reflect one or more light beams emitted by the source group and provided with an outlet opening; a diffuser element coupled to the reflector element substantially at the exit opening and shaped in such a way that the light beams exiting the reflector element pass through the diffuser element.

The projector according to the present invention has a very simple structure and, at the same time, allows to obtain a high homogeneity of the beam and a high efficiency.

In accordance with a preferred embodiment of the present invention, the diffuser element is shaped so as to substantially cover the outlet opening.

This allows the diffuser element to collect all the light beams coming out of the reflector element.

In accordance with a preferred embodiment of the present invention, at least a part of the diffuser element is housed in the reflector element, in particular allowing an effective coupling between the diffuser element and the reflector element.

In accordance with a preferred embodiment of the present invention, the diffuser element is shaped so as to close the reflector element at the outlet opening. This solution prevents any unwanted contaminants from entering the reflector element through the outlet opening.

In accordance with a preferred embodiment of the present invention, the reflector element is provided with a trailing edge delimiting the exit opening and the diffuser element is provided with a peripheral portion, which comprises a recess in which it is housed the trailing edge. The insertion of the trailing edge into the recess makes it possible to simplify the coupling between the reflector element and the diffuser element. Moreover, this coupling is stable even during the rapid and sudden movements to which the projector is subjected during use.

In accordance with a preferred embodiment of the present invention, the diffuser element is made in a single piece. In this way, the diffuser element, in addition to being simple to make, is also more reliable (less tendency to break / detach during projector operation).

In accordance with a preferred embodiment of the present invention, the diffuser element is made of a material comprising at least a first mixture of polymeric material, preferably silicone.

This allows a simple realization of the diffuser element.

In accordance with a preferred embodiment of the present invention, the diffuser element comprises at least a first zone made of a material comprising the first mixture of polymeric material and at least a second zone made of a material comprising a second mixture of polymeric material different from first mixture of polymeric material.

This allows to diversify the optical and mechanical properties of the diffuser element according to the needs.

In accordance with a preferred embodiment of the present invention, the reflector element comprises an active surface at least partially reflective, which is configured to receive, in use, one or more light beams. According to a first variant, the whole active surface is reflective. According to a second variant, the active surface also comprises at least one zone having diffusive properties. According to a further variant, the whole active surface is reflective but made of a material such that the light beams are reflected partially by specular reflection and partially by diffusion (in particular, without distinction of reflecting area and diffusive area).

In this way, the reflector element is able to improve the mixing of colors.

In accordance with a preferred embodiment of the present invention, the source group comprises a plurality of sources configured to emit a plurality of light beams; the sources are arranged on a substrate and the reflector element is arranged near the substrate and includes an inlet opening to receive the light beams; the entrance opening being shaped in such a way as to collect as many light beams as possible.

This realization allows to optimize the efficiency of the projector.

In accordance with a preferred embodiment of the present invention, the plurality of sources defines an emission surface of the light beams and the inlet opening defines an inlet passage which has an area which is at least equal to the area of the light beam. issue. Through this solution, a further increase in the efficiency of the projector is obtained.

In accordance with a preferred embodiment of the present invention, the projector also comprises a condenser unit arranged downstream of the diffuser element along the emission direction. The condenser group is configured to concentrate the light beam or light beams, preferably on an opening delimited by an optical output element positioned downstream of the condenser group, and thus increase the optical efficiency (luminous flux output) of the projector.

In accordance with a preferred embodiment of the present invention, the condenser group is coupled to the diffuser element. Preferably, the condenser group is coupled to the diffuser element in such a way that one face of the condenser group adheres to a face of the diffuser element.

This allows to avoid an air gap between the condenser unit and the diffuser element to minimize Fresnel optical losses and to reduce the risks of absorption of contamination and / or condensation of moisture.

In accordance with a preferred embodiment of the present invention, the projector also comprises a casing extending along a longitudinal axis having an open end and an optical output element arranged at said open end; the source group, the reflector element and the diffuser element being arranged inside the casing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the attached drawings relating to non-limiting examples of embodiment, in which:

Figure 1 schematically illustrates a side view, with parts removed for clarity, of a projector according to the present invention;

Figure 2 schematically illustrates, in exploded form and with parts removed for clarity, a first detail of the projector of Figure 1;

Figure 3 schematically illustrates a second detail of the projector of Figure 1 with parts removed for clarity; And

- Figure 4 schematically illustrates a side view, with parts removed for clarity, of a projector according to a second embodiment of the present invention.

PREFERRED FORMS OF IMPLEMENTATION OF THE INVENTION

With reference to Figure 1, the number 1 indicates as a whole a projector, preferably for a stage, configured to generate at least one light beam. In particular, the projector 1 extends along a longitudinal axis B.

The projector 1 comprises at least one lighting device 2, at least an optical output element 3, and a casing 4, which extends along the axis B.

Preferably, the lighting device 2 is housed, at least in part, in the casing 4.

Preferably, the casing 4 is provided with at least one open end in correspondence with which the optical output element 3 is arranged.

In greater detail, the lighting device 2 is configured to generate at least one light beam Preferably, the lighting device 2 extends along a longitudinal axis C, in particular parallel to the axis B.

In a preferred embodiment not shown, the projector 1 further comprises at least one anchoring element (not shown) for fixing and / or mounting the casing 4 to support structures (for example walls, support frames, support bars and more).

Preferably, the projector 1 is also equipped with movement means (not shown) to move the casing 4 according to the scene requirements.

Preferably, the output optical element 3 is positioned so as to be the last optical element that intercepts the light beam emitted by the lighting device 2.

Preferably, the output optical element 3 is a Fresnel type, pebble type or plane-convex type lens.

With particular reference to Figure 1, the lighting device 2 comprises at least one source unit 6 configured to emit one or more light beams in an emission direction D1 and a mixing unit 7 arranged downstream of the source unit 6 along the emission direction D1 . Preferably, the source group 6 is configured to emit a plurality of light beams having different emission spectral bands.

In other words, the source group 6 is of the multicolored type.

With particular reference to Figures 1 and 3, the source assembly 6 comprises a plurality of sources 11, preferably of the LED type. In particular, each source 11 is configured to emit a respective light beam having a determined emission spectral band.

Preferably, the sources 11 are configured to emit light beams with at least two different emission bands (in other words, of two different colors).

Preferably the sources 11 are configured to emit beams having at least four different emission bands, even more preferably at least six different emission bands.

In a preferred but non-limiting embodiment, the source group 6 also comprises a substrate 12 on which the sources 11 are arranged.

Preferably, the source unit 6 also comprises a protective layer (not illustrated in the attached figures), in particular made of glassy material, arranged on the sources. More preferably, the protective layer comprises an anti-reflective coating.

Preferably, the sources 11 as a whole define an emission surface for the light beams which preferably can have a circular, square, elliptical, hexagonal, polygonal cross section or any other shape.

Preferably, the sources 11 are coupled to the substrate 12 by chip-on-board (COB) technology.

Alternatively, the sources 11 can be coupled to the substrate 12 by means of surface mount technology (SMT). In this case, the substrate 12 is preferably a printed circuit.

In the preferred and non-limiting embodiment, the sources 11 are coupled to the substrate 12 so as to form a matrix.

Preferably, the sources 11 are connected to each other, in pairs, by means of connecting wires (not shown).

With particular reference to Figures 1 to 3, the mixer unit 7 comprises a reflector element 13, a diffuser element 17 and, preferably, at least one condenser unit 18.

In greater detail, the condenser group 18 is arranged downstream of the diffuser element 17 along the emission direction D1.

Preferably, the reflector element 13, the diffuser element 17 and, in particular also the condenser group 18, are arranged coaxially. Preferably, the source group 6 is also coaxial with the mixer group 7.

Preferably, the reflector element 13 is configured to reflect one or more light beams emitted by the source group 6 and is provided with at least one outlet opening 16, in particular it includes the outlet opening 16.

In particular, the reflector element 13 is also provided with an inlet opening 14 opposite the outlet opening 16 along the direction D1.

In particular, the reflector element 13 is arranged with respect to the source group 6 in such a way that one or more light beams emitted by the source group 6 first pass through the inlet opening 14 and then the outlet opening 16. In other words, the reflector element 13 is arranged in such a way that the outlet opening 16 is downstream of the inlet opening 14 along the emission direction D1.

Preferably, the source group 6 is arranged substantially at the inlet opening 14.

Preferably, the outlet opening 16 has a passage section greater than the passage section of the inlet opening 14.

In the non-limiting example described and illustrated here, the reflector element 13 is substantially defined by a truncated conical element associated with the source group 6.

In particular, the reflector element 13 also includes an active (internal) surface 15, preferably to reflect (and / or direct) at least a part of the light beam or beams towards the outlet opening 16.

More specifically, the reflector element 13 also includes a passive (external) surface, opposite to the active surface 15, which, in use, does not receive the light beam or beams.

In a preferred but non-limiting embodiment, the reflector element 13 is defined by a tubular wall 19, preferably frusto-conical, in particular extending around an axis C. In the illustrated non-limiting example, the axis C coincides with axis B.

In the embodiment illustrated, the tubular wall 19 has a truncated cone shape. However, in alternative embodiments, the tubular wall 19 can have different shapes such as a truncated cube shape or others.

The tubular wall 19 comprises the active surface 15 (defined by at least a portion of the internal surface of the tubular wall 19) and the passive surface (defined by the external surface of the tubular wall 19).

The tubular wall 19 defines an internal space 20 into which the active surface 15 faces.

Preferably, the outlet opening 16 is arranged at a first end of the tubular wall 19 and the inlet opening 14 is arranged at a second end of the tubular wall 19 opposite the first end.

In the embodiment illustrated, the reflector element 13, in particular the tubular wall 19, is provided with (includes) a (peripheral) trailing edge 25 delimiting the exit opening 16.

Preferably, the reflector element 13 comprises a base wall 26 on which the inlet opening 14. More preferably, the base wall 26 is connected to the tubular wall 19 at the second end of the tubular wall 19 and, in particular is oriented transversely to the tubular wall 19.

In a preferred but non-limiting embodiment, the tubular wall 19 is inclined with respect to the axis C. In particular, the tubular wall 19 and the axis C define an opening angle 22 which preferably varies between about 20 ° and about 50 °, preferably between about 29 ° and about 45 °.

In a preferred embodiment, the active surface 15 has at least one reflecting area.

In a preferred non-limiting embodiment, the reflecting area covers the entire active surface 15 (in other words, the entire active surface 15 is reflective).

Preferably, at least the reflecting zone is configured to reflect, in particular it comprises a material configured to reflect, the light beams in a partially specular and partially diffusive way.

In a further non-limiting embodiment, all the active surface 15 is reflective and comprises a material made in such a way that the light beams incident on it are reflected partially by specular reflection and partially by diffusion.

In an alternative non-limiting embodiment, the active surface 15 includes at least the reflecting area and at least one diffusive area. Preferably, the active surface 15 comprises a plurality of reflecting zones and diffusive zones which alternate with each other.

Preferably, the active surface 15 has, in particular the reflecting areas, a reflectivity of at least about 90%, preferably of at least about 95%.

In a preferred embodiment, the reflector element 13 is made of metallic material, preferably of aluminum treated with particular processes of anodization or physical vapor deposition (PVD) such as to ensure high total reflection values (in particular, both specular which spread).

Alternatively, the reflector element 13 can be made of a polymeric material resistant to operating temperatures, such as for example polybutylene terephthalate (PBI).

Preferably, the reflector element 13 is arranged in proximity of the substrate 12, in particular downstream of the substrate 12 along the direction D1. More preferably, the reflector element 13 is spaced from the substrate 12 in such a way as to avoid electrical contact with conductive portions of the substrate 12 and / or sources 11.

Preferably, the reflector element 13 is arranged in such a way that the distances between the sources 11 arranged externally on the substrate 12 and the reflector element 13 are substantially the same.

Preferably, the inlet opening 14 is shaped in such a way as to collect as many light beams as possible. In other words, the inlet opening 14 is shaped in such a way that it can be crossed by all the beams emitted by the sources 11.

In particular, the entrance opening 14 defines an entrance passage that has an area at least equal to an area of the emission surface.

More specifically, the extension of the inlet passage is greater than the extension of the emission surface of the source group 6.

Preferably, the inlet opening 14 is shaped in such a way as to substantially surround the sources 11.

Preferably, the shape of the inlet passage of the inlet opening 14 is chosen according to the shape of the emission surface of the source assembly 6, which for example can have a circular, square, elliptical, hexagonal, polygonal or any other shape. .

In the specific case described, the inlet opening 14 has a circular cross section having a diameter chosen from about 12 mm to about 22 mm, preferably between about 15 mm and about 19 mm.

Preferably, the (transversal) dimension of the exit aperture 16 can be sized according to the focal length of the optical output element 3 and the minimum width of the light beam exiting the projector 1, preferably measured in degrees. In a non-limiting form of implementation, the minimum amplitude is defined for example as FWHM - or beam width at half height of the light intensity distribution (also called Beam Angle). In an alternative non-limiting form of implementation, the minimum amplitude is defined by the beam amplitude at 10% of the maximum light intensity value (also called Field Angle).

In the specific case described, the outlet opening 16 has a circular cross section having a diameter between about 30 mm and about 44 mm, more preferably between about 35 mm and about 39 mm.

Preferably, the longitudinal distance (length) along the C axis between the inlet opening 14 and the outlet opening 16 is dimensioned in such a way as to limit the losses of the light beams caused by the reflections in the reflector element 13 while simultaneously maintaining the uniformity of colors, taking into account that both the losses and the uniformity of the colors increase with increasing longitudinal distance.

Preferably, the longitudinal distance can be comprised between about 6 mm and about 22 mm, preferably between about 10 mm and about 18 mm.

With particular reference to Figures 1 to 3, the diffuser element 17 is coupled to the reflector element 13 in correspondence with the outlet opening 16 and is preferably shaped in such a way that the light beams leaving the reflector element 13 pass through the diffuser element 17.

The diffuser element 17 is shaped in such a way as to exhibit diffusive optical properties. In other words, the diffuser element 17 is configured in such a way as to deflect the incoming light beams in a disorderly, ie random, manner so as to mix them and thus conveniently generate a mixed and homogeneous light beam at the output.

Preferably, the diffuser element 17 is shaped / shaped in such a way as to cover (substantially) the outlet opening 16.

In particular, the diffuser element 17 is arranged, at least in part, in contact with (at least a contact portion of) the active surface 15 of the reflector element 13.

In one embodiment, the diffuser element 17 is shaped to close, preferably seal, the reflector element 13 at the outlet opening 16, in particular to prevent contamination such as dust from entering the reflector element 13 through the outlet opening 16.

Preferably, the diffuser element 17 comprises at least one interaction portion 27 configured to adhere to the contact portion of the active surface 15. In particular, the interaction portion 27 is complementary to the reflector element 13, in particular the tubular wall 19, in correspondence with the outlet opening 16.

In a preferred but non-limiting embodiment, the diffuser element 17 comprises a peripheral portion 28 comprising a recess 29 in which the trailing edge 25 is housed (at least in part). Conveniently, the recess 29 is shaped in such a way such as to perform the function of closing / sealing gasket of the outlet opening 16 of the reflector element 13.

Preferably, the recess 29 has an annular shape.

In the illustrated non-limiting embodiment, the diffuser element 17 is made in a single piece.

Preferably, the diffuser element 17 is made of a material comprising at least a first mixture of polymeric material, comprising in turn for example silicone, polycarbonate (PC), polymethyl methacrylate (PMMA), polymethacrylate methylimide (PMMI), cyclic olefin copolymers (COC ) or other similar substances.

In a preferred but non-limiting embodiment, the diffuser element 17 comprises at least a first zone made of a material having the first mixture of polymeric material and at least a second zone made in turn of a material comprising a second mixture of material polymeric different from the first mixture of polymeric material. Preferably, the second area corresponds to the peripheral portion 28 and, in particular, the first area corresponds to a central portion 30 of the diffuser element 17.

Preferably, the diffuser element 17 can comprise additives, in particular diffuser additives and / or reflective additives, able to at least partially define the optical properties of the diffuser element 17.

More specifically, the first and / or second mixture of polymeric material may comprise / comprise the additives. In particular, the first and second mixture of polymeric material can have concentrations and / or types of additives which are variable and / or different from each other.

Preferably, the additives used in the first and / or in the second mixture of polymeric material can optionally comprise: particles of titanium dioxide and / or alumina.

The diffuser element 17 comprises an inlet surface 31 of the light beam or beams, in particular facing the reflector element 13, more particularly towards the internal space 20, and an outlet surface 32 of the light beam or beams of opposite base. to the inlet surface 31. In other words, preferably the outlet surface 32 is arranged on the opposite side with respect to the reflector element 13, in particular with respect to the internal space 20 so as to be separated from them. According to what is shown in the exemplary embodiment shown in the accompanying Figures, the outlet surface 32 is arranged downstream of the inlet surface 31 along the direction D1. Preferably, the outlet surface 32 has a size such as to ensure that the outlet 16 is closed / covered by the diffuser element 17.

With particular reference to Figures 1 and 3, the condenser unit 18 is configured to concentrate the light beam or beams. Preferably, the condenser group 18 is configured to collect the light beam or light beams coming out of the diffuser element 17 and concentrate them on the opening defined by the optical output element 3.

With particular reference to figures 1 to 3, the condenser group 18 is coupled to the diffuser element 17. Preferably, the condenser group 18 adheres to the diffuser element 17.

Preferably, the condenser group 18 is coupled to the diffuser element 17 in such a way that one face of the condenser group 18 adheres to a face of the diffuser element 17.

In a preferred but non-limiting embodiment, the condenser group 18 comprises at least one condenser lens 33, preferably coupled, more preferably arranged in such a way as to be adherent to the diffuser element 17.

In the non-limiting example described and illustrated here, the condenser assembly 18 comprises a condenser lens, in particular of the flat convex type.

A variant not illustrated provides that the condenser group 18 is defined by a group of lenses coupled together.

Preferably, the condenser lens 33 and the diffuser element 17 can be connected to each other in such a way as to be mutually adherent, for example through a processing process chosen from dispensing, hardening, overmoulding or gluing.

Preferably, the lens 33 comprises a respective input surface 34, preferably being in contact with the output surface 32, and a respective output surface 35, in particular opposite to the input surface 34.

In the embodiment illustrated, the inlet surface 34 is planar. In an alternative embodiment, the input surface 34 can be curved to increase the optical power of the lens.

Preferably, the output surface 35 is curved, in particular convex towards the optical output element 3. Alternatively, the output surface 35 can be of the Fresnel type to conveniently reduce the weight.

In a preferred but non-limiting embodiment, the lens 33 is made of glass.

In figure 4, the number 1 'illustrates a projector according to an alternative embodiment in accordance with the present invention. Projector 1 'is similar to projector 1 and for this reason it is described below limitedly to the differences with respect to projector 1 itself, indicating with the same reference numbers parts that are the same or equivalent to parts already described for projector 1.

The projector 1 'differs from the projector 1 in that the lighting device includes a diffuser element 17' instead of the diffuser element 17.

The diffuser element 17 'is similar to the diffuser element 17 and for this reason it is described hereinafter limitedly to the differences with respect to the diffuser element 17 itself, indicating with the same reference numbers parts that are the same or equivalent to parts already described for the element diffuser 17.

In particular, the diffuser element 17 'differs from the diffuser element 17 in that the peripheral portion 28 is devoid of the recess 29.

In particular, at least part of the diffuser element 17 'is housed in the reflector element 13, in particular to close, more particularly to seal, the reflector element 13 at the outlet opening 16.

With reference to the exemplary embodiment shown in Figure 4, the diffuser element 17 'can be coupled to the reflector element 13 in such a way as to present the flat annular peripheral portion 28 placed against the trailing edge 25 of the reflector element 13 and the interacting portion 27 which is engaged on the outlet opening 16 of the reflector element 13 in such a way as to close and / or seal it.

From an examination of the characteristics of the projector 1 and / or the projector 1 'according to the present invention, the advantages that the latter allows to obtain are evident.

In particular, projectors 1 and 1 'have good characteristics of efficiency and color homogeneity and are easy to make.

Furthermore, it is possible to realize a projector 1 which can operate with LED light sources of various colors without the need to use a complicated optical system.

Finally, it is clear that the projectors 1 and 1 'described and illustrated here may be subject to modifications and variations that do not go beyond the scope of protection defined by the claims.

Claims (14)

CLAIMS 1.- Projector (1, 1 '), preferably for stage, comprising: - at least one source group (6) configured to emit one or more light beams along an emission direction (D1); - at least one reflector element (13) configured to reflect one or more light beams emitted by the source unit (6) and provided with an outlet opening (16); and - at least one diffuser element (17, 17 ') coupled to the reflector element (13) substantially in correspondence with the outlet opening (16) and shaped in such a way that the light beams leaving the reflector element (13) pass through the diffuser element (17, 17 '). 2.- Projector according to claim 1, in which the diffuser element (17, 17 ') is shaped so as to substantially cover the outlet opening (16). 3.- Projector according to claim 1 or 2, in which at least a part of the diffuser element (17, 17 ') is housed in the reflector element (13). 4.- Projector according to one of the previous claims, in which the diffuser element (17, 17 ') is shaped so as to close the reflector element (13) at the outlet opening (16). 5.- Projector according to any of the preceding claims, in which the reflector element (13) is provided with a trailing edge (25) delimiting the exit opening (16); the diffuser element (17, 17 ') being provided with a peripheral portion (28), which includes a recess (29) in which the trailing edge (25) is housed, at least in part. 6.- Projector according to any of the preceding claims, in which the diffuser element (17, 17 ') is made in a single piece. 7.- Projector according to any of the preceding claims, in which the diffuser element (17, 17 ') is made of a material comprising at least a first mixture of polymeric material, preferably silicone. 8.- Projector according to claim 7, wherein the diffuser element (17, 17 ') comprises at least a first zone made of a material comprising the first mixture of polymeric material and at least a second zone made of a material comprising a second mixture of polymeric material different from the first mixture of polymeric material. 9.- Projector according to any of the preceding claims, in which the reflector element (13) comprises an active surface (15) which includes at least one reflecting area and / or at least one diffusing area. 10.- Projector according to any one of the preceding claims, wherein the source group (6) comprises a substrate (12) and a plurality of sources (11), which are arranged on the substrate and are configured in such a way as to emit respective beams bright; in which the reflector element (13) is arranged near the substrate (12) and includes an entrance opening (14) to receive the light beams, which is shaped in such a way as to collect as many light beams as possible. 11.- Projector according to Claim 10, wherein the plurality of sources (11) defines an emission surface of the light beams and the inlet opening (14) defines an inlet passage which has a respective area which is at least equal to a respective area of the emitting surface. 12.- Projector according to any of the preceding claims, comprising at least one condenser group (18) arranged downstream of the diffuser element (17, 17 ') along the emission direction (D1). 13. Projector according to claim 12, in which the condenser group (18) is coupled to the diffuser element (17, 17 '). 14. Headlamp according to claim 13, wherein the condenser group (18) is coupled to the diffuser element (17, 17 ') in such a way that one face (34) of the condenser group (18) adheres to a face (32) of the diffuser element (17, 17 '). 15. A projector according to any one of the preceding claims, further comprising; - at least one casing (4) extending along a longitudinal axis (B) having an open end; and - at least one optical output element (3) arranged at said open end; the source group (6), the reflector element (13) and the diffuser element (17, 17 ') being arranged inside the casing (4).