Light guide and associated electrical device

Abstract

Light guide and associated electrical apparatus This light guide (110) comprises a body (120) having a substantially planar output surface (112) and an input surface (122) configured to capture an incident light flux (F106) emitted by a light-emitting diode (106). The input surface (122) comprises a central face (124) straddling a median plane (M120) and, on each side of the median plane (M120), a first lateral face (131) and a second lateral face (132), such that the incident light flux (F106) is divided into three separate light fluxes. The body (120) also comprises external reflection faces, which are each configured to reflect the light fluxes associated with each lateral face towards the output surface (112). Figure for abstract: Figure 4

Description

Title of the invention: Light guide and associated electrical device

[0001] The invention relates to a light guide for an electrical device, as well as to an electrical device comprising such a light guide.

[0002] The subject of interest here is electrical or electronic devices comprising a light indicator illuminated by one or more LEDs, the English acronym for light-emitting diodes. The indicator is located on a front face of the electrical device, so as to indicate to the user operating states of the electrical device. The LED(s) are generally arranged on an electronic card, the electronic card being housed in an insulating case of the electrical device, so as to guarantee a minimum insulation distance between the electrified components of the electrical device and the user.

[0003] It is known to use a light guide made of an electrically insulating material, so as to guide the light emitted by the LED to the front face of the electrical appliance. An input surface of the light guide is located opposite the LED, while an output surface of the light guide forms the indicator light. The output surface is generally orthogonal to an axis of light guide length. The input surface is arranged opposite the LED, so as to capture a flow of light emitted by the LED, while the output surface is distant from the LED - and by extension distant from the input surface - by a minimum distance. For example, the standard IEC 947-1:2019 - tables 13 and 15 - defines insulation classes, which correspond to minimum distances to be respected between the electrified points - or likely to be electrified - and the user.The insulation distances depend in particular on the insulation class sought, and the electrical voltage under which the electrical circuit breaker operates. In the context of this description, two electrical voltage intervals are mainly considered, with a first interval corresponding to a voltage less than or equal to 690V, and a second interval corresponding to a voltage strictly greater than 690V. For a voltage greater than 690V, insulation class 1 requires a clearance in the air greater than 7 mm, and creepage distances greater than 10 mm. Insulation class 2 doubles these distances. For a voltage less than 690 V, insulation class 2 requires a clearance in the air greater than 10 mm.

[0004] Particular interest is given to LEDs having an elongated shape, for example an oblong shape. Thus, the output surface has an elongated shape along a width axis. It is known to arrange several LEDs next to each other along the width axis to form such an elongated LED, however this configuration results in high electrical energy consumption. For reasons of limitation power consumption, we are trying to limit as much as possible the number of LEDs used to form an elongated indicator light, preferably with a single LED.

[0005] It is known to use a light guide having a generally trapezoidal shape, the input surface and the output surface being parallel to each other, the input surface being shorter than the output surface along the width axis. In a known manner, the longer the light guide, the more homogeneous the output flux, thanks in particular to the multiple reflections of the light rays on the side walls of the light guide. For example, it is considered that the output flux is substantially homogeneous when the height of the light guide is greater than 2.5 times the width of the output surface. Such a light guide is however relatively bulky, which is impractical.

[0006] It is known to add dispersing materials, for example in powder form, to the light guide material. However, the intensity of the output flux is attenuated as soon as the light guide has a height greater than a few millimeters, which is not desirable, in particular when the light source is limited to a single LED.

[0007] It is these problems that the invention more particularly intends to address, by proposing a light guide having an elongated output surface, having a relatively homogeneous output flux, with little light loss, from a single LED.

[0008] For this purpose, the invention relates to a light guide for an electrical appliance, the light guide comprising a body, which is made of an electrically insulating material, the material comprising a matrix having an optical index of between 1.4 and 1.6 and a light transmission coefficient greater than 90% per millimeter, the body having overall a prism shape extending along a thickness axis, the body having, in projection in a plane transverse to the thickness axis, a section comprising: - an output surface, which is geometrically supported by a plane orthogonal to a height axis and which has an elongated shape along a width axis, the width axis being orthogonal to the height axis, the thickness axis, the width axis and the height axis together forming an orthogonal reference frame, - an input surface, which is configured to capture an incident light flux emitted by a light-emitting diode when the light-emitting diode is located opposite the input surface, the input surface being aligned with the output surface along the height axis, so that the captured light flux mainly emerges through the output surface, - the body has a generally symmetrical shape with respect to a median plane of the light guide, the median plane being orthogonal to the width axis,

[0009] in which: - the entrance area includes: • a central face, which is located astride the median plane, the central face having two opposite lateral edges, which are parallel to the thickness axis, and • on each side of the median plane, several lateral faces, which extend the central face from the lateral edge located on the same side of the median plane, the lateral faces including a first lateral face and a second lateral face, the first lateral face being interposed between the central face and the second lateral face, - on each side of the median plane, and in projection in the transverse plane, the central face, the first lateral face and the second lateral face form angles between them configured so that the incident light flux, emitted by the light-emitting diode and passing through the entry surface, is divided, by refraction upon passing through the entry surface, into three distinct light fluxes, the three light fluxes including: • a central flux, which corresponds to the portion of the incident light flux refracted upon passing the corresponding portion of the central face, the body being configured so that the central flux opens onto a central portion of the exit surface, forming a central outgoing flux, • a first flux, which corresponds to the portion of the incident luminous flux refracted upon passing the first lateral face, • a second flux, which corresponds to the portion of the incident luminous flux refracted when passing the second lateral face, - the body also comprises, on each side of the median plane, external reflection faces, which are interposed between the exit surface and the entry surface, each external face being associated with a respective lateral face and being configured to reflect the portion of the luminous flux associated with the corresponding lateral face towards the exit surface, the external reflection faces including: • a first external reflection face, which is associated with the first lateral face, and which is configured to reflect the first flux inside the light guide, so that the first flux thus reflected opens onto a first portion of the output surface, forming a first outgoing flux, • a second external reflection face, which is associated with the second lateral face, and which is configured to reflect the second flux inside the light guide, so that the second flux thus reflected opens onto a second portion of the exit surface, forming a second outgoing flux, - the central outgoing flow, the first outgoing flow and the second outgoing flow together form an outgoing flow from the outlet surface, - on the exit surface, the second portion is interposed between the first portion and the central portion.

[0010] Thanks to the invention, the light guide makes it possible to capture the luminous flux of an LED and to distribute the luminous flux thus captured over the output surface significantly longer than the LED, with a substantially homogeneous luminous intensity for the user. The use of a material with a high transmission coefficient, in other words with good transparency, allows the use of a single LED, which is energy-saving.

[0011] According to advantageous but not obligatory aspects of the invention, such a control unit may incorporate one or more of the following features taken in isolation or in any technically admissible combination: - A vector orthogonal to each external reflection face forms, with an axis orthogonal to the associated lateral face, an angle, greater than the limit angle Olim of reflection defined by the formula:

[0012] Ibn = S*11'1 ( '

[0013] where N120 is the optical index of the material of the light guide body. - The first lateral face forms, with the central face, an angle between 110° and 130°, while the second lateral face forms, with the first lateral face, an angle between 150° and 180°. - The body is made of a heat-injectable synthetic polymer material, preferably polycarbonate or polymethyl methacrylate acrylic. - The body has a front face and a rear face, which are parallel to the transverse plane and which are oriented opposite each other, the outlet face connecting the front face to the rear face,

[0014] while at least on one side of the median plane, the body has a pair of recesses, which are formed in hollows on the front face and on the rear face and which are arranged symmetrically with respect to the transverse plane,

[0015] and that each recess has, in projection onto the transverse plane, a profile defining three main sides, which include: • a first side, which is delimited by the first flow after reflection on the first external face, • a second side, which is delimited by the second flow after reflection on the second external face, and • a third side, which is delimited by the central flow between the central face and the exit surface. • The recesses of the same pair create a thinned portion of the body between them, whereas the thinned portion has a thickness, measured along the thickness axis, of between 20 and 50% of a total thickness of the body, preferably of between 30 and 40%, more preferably substantially equal to 33%. • The recesses are through and connect the front face to the rear face, through the body. • The first side of each recess is polished, so as to reflect the first flow after reflection on the first external reflection.

[0016] The invention also relates to an electrical apparatus, which comprises: - a case, which is made of an insulating material and which has a front face, - a light-emitting diode, which is received in the housing, - a light guide as defined previously, the output surface opening onto the front face of the case, while the input surface is located opposite the light-emitting diode.

[0017] Advantageously: - the electrical device is a control unit of an electrical circuit breaker, the front face being configured to be oriented towards the user when the control unit is in a normal operating configuration.

[0018] The invention also relates to an electrical circuit breaker, which comprises: - a cut-off unit, comprising at least one cut-off device and an actuator, the cut-off device being triggerable by means of the actuator, - the electrical device as defined previously,

[0019] in which: - the cut-off unit has a receptacle, which opens onto a front face of the cut-off unit, • the control unit is received in the receptacle of the cut-off unit, so that the front face of the control unit is substantially aligned with the front face of the cut-off unit.

[0020] The invention will be better understood, and other advantages thereof will appear more clearly in the light of the following description of an embodiment of a light guide, of an electrical device and of an electrical circuit breaker, in accordance with its principle, given solely as an example and made with reference to the attached drawings, in which:

[0021] - [Fig.l] [Fig.l] represents respectively, on two inserts a) and b), a view in perspective and a partially exploded perspective view of an electrical circuit breaker according to the invention, the electrical circuit breaker comprising a control unit, also according to the invention;

[0022] - [Fig.2] [Fig.2] is a perspective view of the control unit of [Fig.l], the control unit comprising a light guide according to a first embodiment of the invention;

[0023] - [Fig.3] [Fig.3] is a perspective view of the light guide of [Fig.2] and of a electronic card of the control unit;

[0024] - [Fig.4] [Fig.4] represents, on two inserts a) and b), a side view of the guide light of [Fig.2];

[0025] - [Fig.5] [Fig.5] represents, on three inserts a), b) and c), a section of the light guide of [Fig.2] and light guides according to other embodiments of the invention, and

[0026] - [Fig.6] [Fig.6] is a perspective view of a light guide conforming to another embodiment of the invention.

[0027] An electrical circuit breaker 10 is shown in [Fig.l]. The electrical circuit breaker 10, also simply called circuit breaker 10, is here a multi-pole circuit breaker, in particular a three-pole circuit breaker. The number of poles is not limiting. In a known manner, a multi-pole electrical circuit breaker comprises, for each electrical pole, input and output power terminals, which are respectively connected or electrically isolated from each other by a circuit breaker cut-off device. The cut-off device comprises, for example, separable movable contacts, which are received in a cut-off chamber of the electrical circuit breaker 10 and whose movements are controlled by an actuator. Thus, the cut-off device can be triggered by the actuator. The cut-off chambers are here materialized by three grids 12 visible on an upper face of the circuit breaker 10, the other elements of the cut-off device not being shown.

[0028] The electrical circuit breaker 10 is intended to be used within an electrical installation, for example to control the power supply of a machine tool. In a normal configuration of use, the electrical circuit breaker 10 is generally placed within an electrical cabinet, the electrical circuit breaker 10 having a front face 14, which is oriented towards the user standing in front of the electrical cabinet. The electrical cabinet is not shown.

[0029] The electrical circuit breaker 10 comprises a cut-off unit 16, which in particular comprises each of the cut-off chambers, as well as the cut-off device and the associated actuator.

[0030] The electrical circuit breaker 10 advantageously comprises a faceplate 18, which is removable from the rest of the cut-off unit 16. The faceplate 18 is made of an electrically insulating material and extends generally along a front plane P14, which defines a portion of the front face 14 of the electrical circuit breaker 10, and by extension of the cut-off unit 16. The faceplate 18 thus serves to protect the user of the cut-off unit 16. In [Fig.l] a), the faceplate 18 is shown assembled to the cut-off unit 16, which corresponds to a normal usage configuration of the circuit breaker 10. In [Fig.l] b), the faceplate 18 is distant from the cut-off unit 16, this configuration being found for example during maintenance of the cut-off unit 16

[0031] The electrical circuit breaker 10 also comprises a control unit 20. The control unit 10 is configured to analyze states of the cut-off unit 16 and is configured to trigger the actuator according to the results of these analyses, thus separating the separable contacts.

[0032] The control unit 20 comprising a front face 22. The front face 22 has a generally planar shape and is geometrically carried by a front plane P22, which is orthogonal to a depth axis A22 of the control unit 20. The front face 22 is oriented towards the user when the control unit 20 is in a normal configuration of use. The front face 22 thus defines a front direction D22, which is parallel to the depth axis A22. The front direction D22 is represented by an arrow. The concepts of directions such as “front”, “back”, “up”, “down”, etc., are defined in relation to the elements as represented in the drawings, knowing that it may be otherwise in reality.

[0033] The front panel 18 comprises a window 19, through which the front face 22 of the cutting unit 20 is visible. The window 19 is preferably closed by a transparent flap. The flap is not shown.

[0034] The control unit 10 is assembled to the cut-off unit 16 in a reversible manner. In the example of figures 1a) and 1b), the control unit 20 is shown in the configuration assembled to the cut-off unit 16. The control unit 20 is shown in isolation in [Fig.2].

[0035] The cut-off unit 16 provides a receptacle, which opens onto a front face 14 of the cut-off unit 16 and in which the control unit 20 is received, so that the front face 22 of the control unit 20 is substantially aligned with the front face 14 of the cut-off unit 16, as illustrated in particular in [Fig.l] a). The receptacle is not shown.

[0036] The control unit 20 is now described. The control unit 20 comprises a housing 30, which is made of an insulating material and which forms a volume for receiving various components of the control unit 10, as detailed later.

[0037] The housing 30 includes a front subassembly 100. By extension, the subassembly 100 belongs to the control unit 20. The front subassembly 100 comprises a central portion 102, which is generally planar, which has a front side 102A and a rear side opposite the front side 102A.

[0038] The central portion 102 is here configured to receive at least one human-machine interface element 104. The front side 102A of the central portion 102 is preferably oriented in the front direction D22. A human-machine interface is also designated by its acronym HMI, or MHI in English. The human-machine interface elements 104 are also simply noted “HMI elements” 104. In the illustrated example, the central portion 102 comprises several HMI elements 104. The HMI elements 104 here include several indicator lights 104A, a transparent portion 104B, through which a screen can be observed, and several buttons 104C. These examples are not limiting, the type, number and arrangement of the HMI elements 104 can be changed during the design of the front subassembly 100.

[0039] The front subassembly 100 is assembled to the rest of the control unit 20, in particular to the housing 30, in a reversible manner. It is thus possible to replace the front subassembly 100 in the event of a malfunction. The central portion 102 thus forms a portion of the front face 22 of the control unit 120.

[0040] The control unit 20 comprises an electronic card 32, which is housed in the housing 30. In [Fig. 3], the housing 30 is shown in transparency, an outline of the housing 30 being shown schematically in dotted lines. The electronic card 32 comprises a printed circuit and several electronic components such as a microprocessor, one or more light-emitting diodes, etc. With reference to [Fig. 3], each of the indicator lights 104A is here obtained by means of a light-emitting diode 106, which is mounted on the electronic card 32, which generates a luminous flux and whose luminous flux is guided, to the surface 22 of the control unit 20, by a respective light guide 108. Each light guide 108 comprises an output surface 110, through which the luminous flux emitted by the corresponding diode 106 exits, thus forming the corresponding indicator light 104A. 108 light-emitting diodes are also referred to by their acronym DEL - or LED in English -.In the context of the present description, the light-emitting diodes are also simply called “diodes”. In the illustrated example, the electronic card 32 comprises three diodes 106, which are each associated with a respective light guide 108.

[0041] The light guides 108 include an elongated light guide 110, which has an elongated exit surface 112. The elongated light guide 110, also simply called elongated guide 110, is here located between the two other light guides 108.

[0042] The elongated guide 110 is now described.

[0043] The elongated light guide 110 comprises a body 120, which is made of an electrically insulating material, the material comprising a matrix having an optical index nl20 of between 1.4 and 1.6 and a light transmission coefficient greater than 90% per millimeter. Optionally, other components may be added to the material, for example fillers, in powder form, to assist in the manufacture of the body 120 and / or modify the optical properties of the material of the body 120. The material of the body 120 is thus considered to be optically homogeneous and transparent.

[0044] The body 120 is advantageously made of a synthetic polymer material that can be injected hot. Preferred examples of such materials include polycarbonate, denoted PC, or polymethyl methacrylate acrylic, denoted PMMA. Polycarbonate has, for example, an optical index of the order of 1.6, while PMMA has an optical index of the order of 1.4. Air is considered to have an optical index of 1. The body 120 is advantageously made by hot injection, in an injection mold.

[0045] In a variant not illustrated, the body 120 is made of a mineral material, in particular mineral glass. The light guides thus obtained are of good quality but are more expensive to manufacture.

[0046] The body 120 thus comprises the exit surface 112. The exit surface 112 is preferably generally planar, a normal to the exit surface 112 defining an axis of height H120 of the body 120. The exit surface here has a substantially rectangular shape, the small sides of the rectangle being parallel to an axis of thickness X120 of the body 120, while the large sides of the rectangle are parallel to an axis of width Y120 of the body 120. In the example illustrated, the exit surface 112 has a first dimension, measured along the axis of width Y120 of the body 120, equal to 14 mm, and a second dimension, measured along the axis of thickness XI20, equal to 3.2 mm.

[0047] In a variant not illustrated, the output surface 112 has an oblong, or even elliptical, shape, etc. The thickness axis X120, the width axis Y120 and the height axis H120 together form an orthogonal reference frame.

[0048] The body 120 advantageously has a shape that is generally symmetrical with respect to a median plane M120 of the light guide, the median plane M120 being a plane orthogonal to the width axis Y120.

[0049] The body 120 here generally has a prism shape extending along the thickness axis X120, the body 120 having, in projection in a transverse plane T120 orthogonal to the thickness axis X120, a transverse section with a substantially constant profile.

[0050] The body 120 has a front face 114 and a rear face 115, which are parallel to the transverse plane T120 and which are oriented opposite each other, the outlet face 112 connecting the front face 114 to the rear face 115.

[0051] The cross-section of the body 120 thus comprising the outlet surface 112, as well as an inlet surface 122, which is different from the inlet surface and which is aligned with the outlet surface 112 along the height axis H120.

[0052] In normal usage configuration, one of the light-emitting diodes 106 of the electronic card 32 is located opposite the input surface 122, as illustrated in [Fig.3]#a) or in [Fig.4]. Schematically, a light-emitting diode of the type of diode 106 considered here is configured to generate a light flux F106 of substantially conical shape, characterized by an apex angle. In the context of the present invention, the light flux F106 preferably has an apex angle of the order of 120°. The input surface 122 is configured to capture most of the light flux F106 emitted by the light-emitting diode 106 located opposite. Thus the light flux F106 is an incident flux, which is captured by the input face 122 and then exits mainly via the output surface 112, as explained below.

[0053] Schematically, it is considered that the luminous flux F106 is emitted by a central point 107A located on an upper face 107B of the light-emitting diode. The upper face 107B of the diode 106 is arranged orthogonally to the height axis H120, the central point 107A being aligned with the height axis H120. It is considered here that the upper face 107B of the diode 106 is generally planar, knowing that it may be otherwise in reality. The upper face 107B is thus geometrically carried by an upper plane P107, which is orthogonal to the height axis H120.

[0054] The entry surface 122 comprises several faces, which are here each planar faces and which together form the entry surface 112. Two successive faces of the entry surface 122 form a non-zero angle between them and are arranged in such a way that the entry surface 122 is generally concave, when observed from outside the body 120.

[0055] The inlet surface 122 here comprises a central face 124, which is situated astride the median plane M120. The central face 124 has two opposite lateral edges 126, which are parallel to the axis of thickness X120. On each side of the median plane M120, the inlet surface 120 comprises several lateral faces 128, which extend the central face 124 from the lateral edge 126 located on the same side of the median plane M120. The central face 124 here has a rectangular, or even substantially square, shape, with sides each having a length of approximately 2.5 mm. An upper surface of the diode 106 is here located approximately 3 mm from the central face 124.

[0056] The lateral faces 128 here include, on each side of the median plane M120, a first lateral face 131 and a second lateral face 132, the first lateral face 131 being interposed between the central face 124 and the second lateral face 132.

[0057] On each side of the median plane M120, and in projection in the transverse plane T120, the central face 124, the first lateral face 131 and the second lateral face 132 form angles between them configured so that the incident light flux F106, emitted by the diode 106 and passing through the entry surface 122, is divided, by refraction upon passing through the entry surface 122, into three light fluxes, the three light fluxes including: - a central flux F124, which corresponds to the portion of the incident light flux F106 refracted upon passing the corresponding portion of the central face 124, the body 120 being configured so that the central flux F124 opens onto a central portion of the exit surface 112, forming a central outgoing flux F140, - a first flux F131, which corresponds to the portion of the incident luminous flux F106 refracted upon passing the first lateral face 131, and - a second flux F132, which corresponds to the portion of the incident luminous flux F106 refracted upon passing the second lateral face 132.

[0058] The central flow F124, the first flow F131 and the second flow F132 are shown schematically in [Fig.4] b) by several optical paths represented in dot-dash lines.

[0059] Due to the concavity of the entrance face 122, whereas before the passage of the entrance surface 122, the incident light flux F160 is considered to be continuous, after the passage of the entrance surface 122, the central flux F124 and the first flux F131 diverge from each other, while the first flux F131 and the second flux F132 diverge from each other. By "two diverging fluxes" is meant that the optical paths of each of the two fluxes tend to move away from each other.

[0060] The first lateral face 131 forms, with the central face 124, a first angle al of between 110° and 130°, preferably of between 115° and 125°. In the example illustrated, the first angle al is equal to 120°. The first lateral face 131 here has, in projection onto the transverse plane T160, a length substantially equal to 1.1 mm.

[0061] The second lateral face 132 forms, with the first lateral face 131, a second angle a2 of between 150° and 180°, preferably of between 160° and 170°. In the example illustrated, the second angle a2 is equal to 164°. The second lateral face 132 presents here, in projection on the transverse plane T160, a length substantially equal to 1.3 mm. It is understood that the overall shape of the input face can be adjusted in particular as a function of the size of the diode 106, its distance, etc.

[0062] The body 120 also comprises, on each side of the median plane M120, external reflection faces, which are interposed between the exit surface 112 and the entry surface 122, each external face being associated with a respective lateral face and being configured to reflect the portion of the luminous flux associated with the corresponding lateral face towards the exit surface.The external reflection faces thus include: - a first external reflection face 141, which is associated with the first lateral face 131, and which is configured to reflect the first flux F131 inside the light guide 110, so that the first flux F131 thus reflected essentially opens onto a first portion of the exit surface, forming a first outgoing flux F141, - a second external reflection face 142, which is associated with the second lateral face 132, and which is configured to reflect the second flux F132 inside the light guide 120, so that the first flux F131 thus reflected essentially opens onto a second portion of the exit surface 112, forming a second outgoing flux F142.

[0063] The central outgoing flow F140, the first outgoing flow F141 and the second outgoing flow F142 together form an outgoing flow F112 from the outlet surface 112.

[0064] On the outlet surface 112, the second portion is interposed between the first portion and the central portion, so that the outgoing flow F112 from the outlet surface 112 is substantially homogeneous, as schematically illustrated in [Fig.4] a). In reality, it is advantageous for the central outgoing flow F140, the first outgoing flow F141 and the second outgoing flow F142 to overlap, so as to promote the apparent homogeneity of the outgoing flow F12.

[0065] Advantageously, the outlet face 112, the outlet surface, has a roughness Ra of the order of 1.6 pm, so as to improve the impression of homogeneity of the outgoing flow Fl 12 from the outlet surface 112. The body 120 is here manufactured by hot injection. Each surface of the body 120 thus has a surface condition - in particular a roughness - which is substantially identical to a surface condition of the mold. The roughness of the mold surfaces is evaluated according to a “VDI 3400” scale - acronym for the German “Verein Deutscher Ingenieure”, or Society of German Engineers -, which links the Charmilles index - without unit - and the roughness Ra - in pm - of the mold surfaces. The outlet face 112 thus has a surface condition which corresponds to a Charmilles index 24.

[0066] Advantageously, the entry surface 122 has a so-called “mirror-polished” or “glass-polished” surface. The polished surfaces of plastic parts are generally evaluated according to an “SPI” scale, an acronym for “Society of the Plastics Industry”, since renamed “Plastics Industry Association”. For the purposes of this description, surfaces with a mirror-polished surface finish have an SPI surface finish of level “A2”, which corresponds to a roughness Ra between 0.012 and 0.025 qm.

[0067] Preferably, the first external reflection face 141 is arranged so that the first flux F131 is entirely reflected. Similarly, the second external reflection face 142 is advantageously arranged so that the second flux F132 is entirely reflected.

[0068] Generally speaking, the Snell-Descartes law makes it possible to calculate a limit angle of total reflection 0lim during reflection at the interface between the material of the body 120 and the air, the limit angle being measured relative to a vector orthogonal to the interface considered: — cjn'H [ lim \ N j 20 / where Nair is the optical index of air and N120 is the optical index of the body material 120 of the light guide 110.

[0069] Applied to the present case, considering that the air index Nair is equal to 1, a vector orthogonal to the first external reflection face 141 forms, with a vector orthogonal to the first associated lateral face (131) 131, an angle [3131 greater than the limit angle 0 lim of reflection defined by the formula: lim ~ 2Vno ) where N120 is the optical index of the body material 120 of the light guide 110.

[0070] Similarly, the second external reflection face 142 is arranged so that the second flux F132 is entirely reflected. Thus, a vector orthogonal to the second external reflection face 142 forms, with a vector orthogonal to the associated second lateral face (132) 132, an angle [3132 greater than the limit angle 0 lim of reflection defined by the preceding formula: where N120 is the optical index of the body material 120 of the light guide 110.

[0071] By way of illustration, when the optical index N120 is equal to 1.4, the limit angle 0lim is of the order of 45°, while when the optical index N120 is equal to 1.6, the limit angle 0lim is of the order of 38°.

[0072] Preferably, in projection onto the transverse plane, at any point of each lateral face 128, an axis orthogonal to the lateral face 128 intersects the upper plane P107 of the diode 106 beyond the central point 107A. Thanks to this arrangement, the first flux F131 and the second flux F132 all form a non-zero angle with, respectively, the axis orthogonal to the first lateral face 131 and the axis orthogonal to the second lateral face 132, which then causes the first flow F131 and the second flow F132 to be reflected on the corresponding external reflection face 141 or 142 at an angle of incidence less than the limit angle ôlim.

[0073] The body 120 has recesses 150, which are formed in hollows on the front face 114 and on the rear face 115 and which are arranged symmetrically with respect to the transverse plane T120. The recesses 150 are thus associated two by two, in other words arranged in pairs, each pair being located on one side of the median plane M120. In the example illustrated, the body 120 comprises two pairs of recesses 150, i.e. a total of four recesses 150.

[0074] The recesses 150 make it possible to limit shrinkage phenomena and / or the appearance of bubbles during the cooling of the light guide 110 manufactured by hot injection. In other words, the recesses contribute to improving the optical quality of the light guide, in particular improving the homogeneity of the light intensity on the output face 112.

[0075] As explained previously, the specific shape of the input face 122 means that the light flux F106 is divided into three divergent fluxes F124, F131 and F132. The reflections on the external faces 141 and 142 mean that certain zones inside the body 120, called “dead zones”, are crossed by few light rays. The recesses 150 are thus arranged in these dead zones, so as to limit the loss of light intensity of the outgoing flux F140.

[0076] Each recess 150 has, in projection onto the transverse plane T120, a profile defining three main sides. The three main sides form a triangle and include: - a first side 151, which is delimited by the first flow Fl31 after reflection on the first external face 141, - a second side 152, which is delimited by the second flow F132 after reflection on the second external face 142, and - a third side 153, which is delimited by the central flow F124 between the central face (124) 124 and the outlet surface 112.

[0077] Advantageously, the first side 151 of each recess 150 is polished, in other words has a “mirror-polished” surface, so as to reflect the first flux (F131) after reflection on the first external reflection face (141), as illustrated in [Fig.4] b). Preferably, the first side 151, the second side 152 and the third side 153 are each polished. Preferably, the entire contour of each recess 150 is polished.

[0078] The recesses 150 are preferably partial, that is to say that the recesses 150 of the same pair provide between them a thinned portion 152 of the body 120, the thinned portion 152 being located astride the transverse plane T120, as illustrated in [Fig.5] a). The thinned portion 152 thus forms a bottom of the recesses 150 of the corresponding pair. The thinned portion 152 has a thickness, measured along the thickness axis, of between 20 and 50% of a total thickness of the body, preferably of between 30 and 40%, more preferably substantially equal to 33%. This benefits from the improvement in the optical quality of the light guide 110, while limiting the loss of light intensity of the outgoing flux F140.

[0079] Alternatively, the recesses 150 are through and connect the front face 114 to the rear face 115, through the body 120, as shown in [Fig.5] b). The body 120 then does not include a thinned portion of the type of the thinned portion 152 described previously.

[0080] According to another variant, the body 120 does not comprise a recess of the type of recesses 150 described previously, as shown in [Fig.5] c).

[0081] In the illustrated examples, the body 120 comprises attachment members. The attachment members 160 are provided to facilitate the assembly of the light guide 110 to the front subassembly 100 and here include projections 161 and a recess 162, which are here provided respectively in the front face 114 and the rear face 115.

[0082] Alternatively, the front 114 or rear 115 faces do not include any projection or recess of the type of the projections 161 or the recess 162 described previously, as illustrated in [Fig.6].

[0083] In the illustrated examples, the exit surface 110 is substantially planar. In a variant not shown, the exit surface is curved, for example convex.

[0084] In the illustrated example, the control unit 20 of the electrical circuit breaker 10 is an example of an electrical device using the elongated light guide 110. Of course, the principles of the invention can be transposed to other types of electrical devices, the elongated light guide 110 being particularly suitable for applications requiring both low energy consumption and / or a minimum insulation distance between the electrified components and the user.

[0085] The embodiments and variants mentioned above can be combined with each other to generate new embodiments of the invention.

Claims

1. Claims Light guide (110) for an electrical device (20), the light guide (110) comprising a body (120), which is made of an electrically insulating material, the material comprising a matrix having an optical index of between 1.4 and 1.6 and a light transmission coefficient greater than 90% per millimeter, the body (120) having overall a prism shape extending along a thickness axis (X120), the body (120) having, in projection in a plane transverse (T120) to the thickness axis (X120) a section comprising: • an output surface (112), which is geometrically carried by a plane orthogonal to a height axis (H 120) and which has an elongated shape along a width axis (Y 120), the width axis (Y 120) being orthogonal to the height axis (H120), the thickness axis (X120), the width axis (Y120) and the height axis (H120) together forming an orthogonal reference frame, • an input surface (122), which is configured to capture an incident light flux (F 106) emitted by a light-emitting diode (106) when the light-emitting diode (106) is located opposite the input surface (122), the input surface (122) being aligned with the output surface (112) along the height axis (H120), such that the captured light flux (F106) mainly exits via the output surface (112), • the body (120) has a generally symmetrical shape with respect to a median plane (Ml20) of the light guide (110), the median plane (Ml20) being orthogonal to the axis of width (Y120), in which: • the inlet surface (122) comprises: • a central face (124), which is located astride the median plane (M120), the central face (124) having two opposite lateral edges (126), which are parallel to the thickness axis (X120), and • on each side of the median plane (M120), several lateral faces (128), which extend the central face (124) from the lateral edge (126) located on the same side of the median plane (M120), the lateral faces (128) including a first lateral face (131) and a second lateral face (132), the first lateral face (131) being interposed between the central face (124) and the second lateral face (132), on each side of the median plane (M120), and in projection in the transverse plane (T 120), the central face (124), the first lateral face (131) and the second lateral face (132) form between them angles (a1, a2) configured so that the incident light flux (F 106), emitted by the light-emitting diode (106) and passing through the entry surface (122), is divided, by refraction on passing through the entry surface (122), into three distinct light fluxes, the three light fluxes including: • a central flux (F 124), which corresponds to the portion of the incident light flux (F 106) refracted upon passing the corresponding portion of the central face (124), the body (120) being configured so that the central flux (F 124) opens onto a central portion of the exit surface (112), forming a central outgoing flux (F 140), • a first flux (F131), which corresponds to the portion of the incident luminous flux (F106) refracted upon passing the first lateral face (131), • a second flux (F 132), which corresponds to the portion of the incident luminous flux (F 106) refracted upon passing the second lateral face (132), the body (120) also comprises, on each side of the median plane (M120), external reflection faces, which are interposed between the exit surface (112) and the entry surface (122), each external face being associated with a respective lateral face (128) and being configured to reflect the portion of the luminous flux associated with the corresponding lateral face (128) towards the exit surface (112), the external reflection faces including: • a first external reflection face (141), which is associated with the first lateral face (131), and which is configured to reflect the first flux (F131) inside the light guide (110), so that the first flux thus reflected opens onto a first portion of the exit surface (112), forming a first outgoing flux (F141), • a second external reflection face (142), which is associated with the second lateral face (132), and which is configured to reflect the second flow (F132) inside the light guide (110), so that the second flow thus reflected opens onto a second portion of the exit surface (112), forming a second outgoing flow (F142), • the central outgoing flow (F140), the first outgoing flow (F141) and the second outgoing flow (F142) together form an outgoing flow (F112) from the outlet surface (112), • on the exit surface (112), the second portion is interposed between the first portion and the central portion.

2. A light guide (110) according to claim 1, wherein: • a vector orthogonal to each external face (141, 142) of reflection forms, with an axis orthogonal to the associated lateral face (1 28), an angle ([31, [32), greater than a limit angle 0 lim of reflection defined by the formula: • -1 / 1 \ ( À'i20} where N120 is the optical index of the material of the body (120) of the light guide (110).

3. Light guide (110) according to any one of claims 1 or 2, in which: • the first lateral face (131) forms, with the central face (124), an angle between 110° and 130°, • the second lateral face (132) forms, with the first lateral face (131), an angle between 150° and 180°.

4. A light guide (110) according to any one of claims 1 to 3, wherein: • the body (120) is made of a hot-injectable synthetic polymer material, preferably polycarbonate or poly-acrylic methyl methacrylate.

5. Light guide (110) according to any one of claims 1 to 4, wherein: • the body (120) has a front face (114) and a rear face (115), which are parallel to the transverse plane (T120) and which are oriented opposite each other, the output face (112) connecting the front face (114) to the rear face (115), • at least on one side of the median plane (M120), the body (120) has a pair of recesses (150), which are formed in hollows on the front face (114) and on the rear face (115) and which are arranged symmetrically with respect to the transverse plane (T120), • each recess (150) has, in projection onto the transverse plane (T120), a profile defining three main sides, which include: • a first side (151), which is delimited by the first flow (F 131) after reflection on the first external face (141), • a second side (152),which is delimited by the second flow (F 132) after reflection on the second external face (142), and • a third side (153), which is delimited by the central flow (F 124) between the central face (124) and the exit surface (112).,

6. Light guide (110) according to claim 5, in which: • the recesses (150) of the same pair form between them a thinned portion (152) of the body (120), • the thinned portion (152) has a thickness, measured along the thickness axis (X120), between 20 and 50% of a total thickness of the body (120), preferably between 30 and 40%, more preferably substantially equal to 33%.

7. A light guide (110) according to claim 5, wherein: • the recesses (150) are through and connect the front face (114) to the rear face (115), through the body (120).

8. Light guide (110) according to any one of claims 5 to 7, in which: • the first side (151) of each recess is polished, so as to reflect the first flux (F131) after reflection on the first external reflection (141).

9. Electrical apparatus (20), comprising: • a housing (30), which is made of an insulating material and which has a front face (22), • a light-emitting diode (106), which is received in the housing (30), • a light guide (110) according to any one of claims 1 to 8, the output surface (112) opening onto the front face (22) of the housing, while the input surface (122) is located opposite the light-emitting diode (106).

10. Electrical apparatus (20) according to claim 9, wherein: • the electrical apparatus is a control unit of an electrical circuit breaker (10), the front face (22) being configured to be oriented towards the user when the control unit is in a normal configuration of use.

11. Electrical circuit breaker (10), comprising: • a cut-off unit (16), comprising at least one cut-off device and an actuator, the cut-off device being triggerable by means of the actuator, • the electrical apparatus according to claim 10, in which: • the cut-off unit (10) provides a receptacle, which opens onto a front face (14) of the cut-off unit (16), • the control unit (20) is received in the receptacle of the cut-off unit, so that the front face (22) of the control unit (20) is substantially aligned with the front face (14) of the cut-off unit (16).

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