JP2009259431A - Vehicle lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact field emission lamp-type vehicle lamp capable of obtaining a sufficient amount of light and reducing power consumption by making an effective use of light emitted from a phosphor. <P>SOLUTION: The vehicle lamp comprises: a frame body 7; a cold cathode electron source 1 and an ITO film 4 that are provided inside the frame body 7 apart from each other to form a first electric field; a phosphor body 5 that is disposed at a position inside the frame body 7 where a first electric field is formed, and that is excited by electrons emitted from the cold cathode electron source 1 toward the ITO film 4 such that the phosphor substance emits light; an inner reflector 6 that is disposed to the rear surface side of the phosphor body 5; a lossless gate electrode 2 that is so disposed as to sandwich the first electrode, and forms a second electric field so as to control the first electric field; and a subreflector 12 that is disposed to the front surface side of the phosphor body 5 outside the frame body 7. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicular lamp, and more particularly to a field emission lamp type vehicular lamp suitable as a vehicular headlamp or the like.

  In recent years, a field emission lamp (FEL) that emits light by colliding electrons emitted from an electron source with a fluorescent material of a phosphor and exciting the fluorescent material to emit light has been proposed as a next-generation light source. A vehicle lamp as a light source has also been proposed (see, for example, Patent Document 1).

  FIG. 6 shows the structure of a field emission lamp type vehicle lamp described in Patent Document 1. As shown in FIG. In the vehicular lamp 20 shown in FIG. 5, a cathode (cathode) 21 and an anode (anode) 24 are spaced apart from each other in an internal space 20a that has been previously evacuated and in a depressurized state. Yes. The anode 24 is provided with a phosphor 25 made of a phosphor material on the surface facing the cathode 21. The side wall of the internal space 20a is constituted by a reflector 26, and a reflection member is provided on the inner surface on the internal space 20a side. A lens holder 27 is fixed along an opening edge that defines a reflector opening 26 a that is a substantially circular opening of the reflector 26. The other end of the lens holder 27 is a convex lens 28 fitted with a convex lens rear opening which is a substantially circular opening.

  Further, a circular through hole 22 is formed on the cathode 21 side which is the bottom of the reflector 26 so as to penetrate the inner surface and the outer surface of the reflector 26, and a through hole cover 23 is attached so as to close the through hole 22. Yes. That is, the through hole cover 23 hermetically seals the through hole 22. That is, the decompressed interior space 20a of the vehicular lamp 20 is formed with side walls by the reflector 26, the lens holder 27, and the convex lens 28, and the cathode 21, the anode 24, and the phosphor 25 are hermetically accommodated therein. .

  The cathode 21 is disposed on the rear side of the internal space 20a (the convex lens 28 side is the front side). When a voltage is applied between the cathode 21 and the anode 24 by a power source (not shown) provided outside the internal space 20a, and an electric field is formed between the cathode 21 and the anode 24 by this voltage, the cathode 21 The electrons e− are extracted from the electron e−, and are guided while being accelerated toward the anode 24. The accelerated electron e − collides with the phosphor 25 disposed on the anode 24.

  The phosphor constituting the phosphor 25 is excited when it receives energy of a predetermined amount or more due to collision of electrons e −, transitions to an excited state, and is excited when the excited phosphor returns to the ground state. Light is emitted by emitting energy of the difference between the state and the ground state as light.

  The light emitted from the phosphor 25 is radiated almost 360 degrees in the same direction regardless of the incident direction of the electrons, and the light traveling in the light emitting direction on the front side is refracted by the convex lens 28 as it is and externally emitted. The light emitted to the rear and directed in the rear and side light emission directions is reflected by the reflector 26 and then refracted by the convex lens 28 and emitted to the outside.

Such a field emission lamp type vehicular lamp does not generate heat, has a simple optical system, and has advantages in terms of cost as compared with a vehicular lamp using a conventional bulb or the like.
JP 2006-221979 A

  As described above, in the conventional field emission lamp type vehicle lamp, when a large amount of light or a wide irradiation range is required, the diameter of the convex lens 28 is increased to obtain a desired light distribution, or the cathode 21 and the anode Since it is necessary to increase the applied voltage applied to 24, there is a problem that the vehicular lamp is increased in size. In particular, there is a problem in that it is necessary to design a wide area of the internal space 20a in order to prevent the internal space 20a from becoming hot.

  In addition, since the vehicle headlamps require a light amount and a light distribution range stipulated by laws and regulations, it is necessary to increase the output of the light source, which increases the consumption of the vehicle battery. .

  The present invention has been made in view of the above circumstances, and is a field emission lamp that can effectively use light emitted from a phosphor to obtain a small and sufficient amount of light and reduce power consumption. An object of the present invention is to provide a vehicular lamp.

  In order to solve the above-described problems, a vehicular lamp of the present invention includes a frame, a cathode and an anode that are provided in the frame and are spaced apart from each other to form a first electric field, and a first in the frame. A phosphor that is excited by electrons emitted from the cathode toward the anode and emits light, and disposed on the back side of the phosphor in the frame. A first reflector that is arranged so as to sandwich the first electric field, a control electrode that controls the region of the first electric field by forming a second electric field, and the front surface of the phosphor outside the frame And a second reflector disposed on the side.

  According to this configuration, the light diffused on the front surface side of the phosphor can be reflected effectively in the light emission direction (front surface side) by the second reflector, and can be used effectively. For this reason, the amount of light in the light emitting direction (front side) increases, so that the light source output can be suppressed, and the power consumption can be reduced.

  The first reflector has a free-form surface based on an elliptical surface that forms reflected light that is substantially parallel to the vertical direction and diffuses light in the horizontal direction, and the second reflector includes It has the aspect used as the extension of the free aspect which a 1st reflector has.

  According to this configuration, the first reflector emits light emitted from the fluorescent material toward the rear and side light emission directions of the phosphor by a free-form reflecting surface based on an elliptical surface. Light distribution in the emission direction (front side) can be reflected so as to be substantially parallel light in the vertical direction and diffused light in the horizontal direction. Therefore, it can be effectively used as a vehicular lamp having a light quantity and a light distribution range defined by laws and regulations.

  The present invention further includes a condensing lens that transmits the light emitted from the phosphor, the light reflected by the first reflector and the second reflector, and irradiates the light forward.

  A shade disposed between the phosphor and the condenser lens for switching a light distribution pattern.

  According to this configuration, since the condenser lens and the light source unit that generates light are not integrated, it is not necessary to provide a size of the light source unit according to the diameter of the lens, and the distance between the cathode and the anode can be reduced. . Therefore, the width of the light source unit on the projection direction side can be reduced, and the vehicle lamp can be reduced in size. Furthermore, since the distance between the cathode and the anode is short, a large kinetic energy can be given to electrons extracted from the cathode with a small applied voltage, so that power consumption can be reduced. Further, when the inside of the frame is evacuated, the condensing lens is not integrated and the shape of the frame can be simply configured, so that the workability is good and the manufacturing cost can be reduced. Further, the light emitted from the phosphor by the condensing lens, the light reflected by the first reflector and the second reflector can be effectively irradiated forward, and a plurality of light distributions desired by the shade You can switch patterns. Therefore, it is possible to satisfy the light quantity and the light distribution range defined by laws and regulations as a vehicle headlamp.

  According to the present invention, the light emitted from the phosphor is effectively utilized, the light emitted from the phosphor is effectively utilized, and a small and sufficient amount of light can be obtained to reduce power consumption. A field emission lamp type vehicle lamp can be provided.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Embodiments of the invention will be described below with reference to the accompanying drawings. 1 and 2 show a vehicular lamp shown as an embodiment of the present invention. FIG. 1 is an external perspective view of the vehicular lamp, and FIG. 2 is a cross-sectional view in the vertical direction (vertical direction). In the following description, the upper direction in FIG. 2 will be referred to as the upper direction, the lower direction as the lower direction, the left direction as the front, the right direction as the rear, and the direction perpendicular to the paper surface as the left and right directions.

  In FIG. 1, a vehicular lamp 100 according to the present invention includes a light source unit 10 that is a light emitting unit, a sub-reflector 12, a shade 13, and a condenser lens 14. A sub reflector 12 is provided in contact with the outer surface of the light source unit 10 in the front side frame 3 having a high light transmittance on the front side which is the light irradiation direction of the light source unit 10. Further, a shade 13 for switching the light distribution pattern is disposed on the front side of the sub reflector 12, and a condenser lens 14 is disposed on the front side of the shade 13.

  In FIG. 2, the light source unit 10 is a field emission lamp (FEL) type unit, and the front side frame 3 that is a light-transmitting member such as glass and the internal space are previously evacuated to a reduced pressure state. The frame 7 is sealed. In the internal space of the frame body 7, a cold cathode electron source 1 as a cathode, an ITO film 4 as an anode, a lossless gate electrode 2, a phosphor 5 made of a fluorescent material, and an internal reflector 6 are provided. Has been placed. That is, the cold cathode electron source 1, the ITO film 4, the lossless gate electrode 2, the phosphor 5, and the internal reflector 6 are hermetically accommodated in the internal space of the decompressed frame 7.

  The cold cathode electron source 1 is disposed at the approximate center on the rear side of the frame body 7. The cold cathode electron source 1 has a flat plate shape, for example, and has a cold cathode member on the surface on the anode side. The cold cathode member is composed of carbon nanotubes having a fine surface structure and emits electrons by an electric field formed in the vicinity of the surface.

  The lossless gate electrode 2 is provided in the frame body 7 and is disposed between the cold cathode electron source 1 serving as a cathode and the ITO film 4 serving as an anode. It is an electrode that forms an electric field. A voltage is applied between the lossless gate electrode 2 and the cold cathode electron source 1 by a power source (not shown) provided outside the frame body 7, and the lossless gate electrode 2 and the cold cathode electrons are applied with this voltage. When an electric field is formed between the source 1 and the electron e −, electrons e − are extracted from the cold cathode electron source 1 and are guided to the lossless gate electrode 2 while being accelerated. The lossless gate electrode 2 has a fine mesh structure, for example, and allows electrons e− to pass in the thickness direction of the lossless gate electrode 2, that is, in the direction from the cold cathode electron source 1 to the ITO film 4. It is possible.

  The ITO film 4 is spaced apart from the cold cathode electron source 1 serving as a cathode at the approximate center of the front side of the frame body 7. The ITO film 4 has a very high visible light transmittance of about 90% and has a layer for transporting electrons. The ITO film 4 is an electrode that forms an electric field for accelerating electrons further accelerated from electrons extracted from the cold cathode electron source 1, and the power source is interposed between the ITO film 4 and the cold cathode electron source 1. A voltage is applied by. When a voltage is applied between the ITO film 4 and the cold cathode electron source 1, the electric field formed between the ITO film 4 and the cold cathode electron source 1 is drawn from the cold cathode electron source 1 and is lossless. The electrons e− that have passed through the gate electrode 2 are further guided toward the ITO film 4 while being accelerated.

  The phosphor 5 is disposed substantially at the center on the surface of the ITO film 4 provided on the front side in the frame body 7 on the cold cathode electron source 1 side. The phosphor 5 has, for example, a flat plate shape having an area that is the same as or slightly larger than the surface of the cold cathode electron source 1 that faces the phosphor 5. The fluorescent material constituting the phosphor 5 is excited when it receives energy of a predetermined amount or more from an electron and transitions to an excited state. When the excited fluorescent material returns to the ground state, the excited state and the ground state It emits light by releasing the energy of the difference between them as light. Here, the fluorescent material emits the energy of the difference between the excited state and the ground state as light.

  The internal reflector 6 is provided in the frame 7 and is disposed between the phosphor 5 and the lossless gate electrode 2 so as to surround the rear surface of the phosphor 5. Further, due to the electric field generated between the cold cathode electron source 1 serving as the cathode and the ITO film 4 serving as the anode, the shape of the cold cathode electron source 1 or the phosphor 5 is approximately centered inside the frame body 7. A hole is provided. The internal reflector 6 emits light from the phosphor 5 and reflects the light toward the rear side or the side surface opposite to the light emission direction to the front which is the light emission direction, so that the ITO film 4 and the front frame 3 are reflected. The surface facing the phosphor 5 has a free-form surface based on an ellipsoid, and the surface is mirror-finished such as aluminum vapor deposition or silver paint. .

  The front side frame 3 is made of a highly light transmissive member such as glass, and the light is emitted forward from the phosphor 5 in the light emission direction without loss. As the frame body 7 is downsized, the inside of the frame body 7 sealed in a vacuum state has a part of energy when the accelerated electrons extracted from the cold cathode electron source 1 collide with the phosphor 5 and the fluorescence. Part of the energy emitted by the body 5 together with the light is converted into heat and becomes a high temperature state. Therefore, the frame body 7 is formed of a member having high heat resistance different from that of the conventional soda glass, particularly on the front side frame body 3 close to the ITO film 4 and the phosphor 5 serving as a heat generation source. . Moreover, as for the member with high heat resistance used for the front side frame 3, the member with high light transmittance and high heat resistance, such as heat resistant glass and quartz glass, for example is desirable.

  The sub reflector 12 is provided outside the frame body 7 and has a free curved surface that is the same elliptical surface as the internal reflector 6. Therefore, since it becomes the same focal position as the internal reflector 6, light collection efficiency can be improved and the light quantity to the front surface which is a light irradiation direction can be increased. In other words, it has the same effect as the internal reflector 6 and can be provided outside the light source unit 10, so that it is possible to effectively use the emitted light by improving the light collection efficiency without increasing the size of the light source unit 10. Yes.

  The shade 13 is provided in a vehicle headlamp that requires a plurality of light distribution patterns, and the shade 13 is movable so that light striking the shade 13 is blocked or reflected to change the light distribution ahead of the shade. Can be made. In conventional vehicle headlamps such as incandescent lamps and halogen lamps, the shade was made of metal with excellent heat resistance to prevent heat from the light source, but in this embodiment, heat does not reach from the light source. Therefore, since a low-priced material such as plastic can be used, the cost can be reduced.

  The condenser lens 14 transmits the light emitted from the phosphor 5 and the light reflected by the internal reflector 6 and the sub reflector 12 and irradiates the light forward. The condensing lens is excellent in light transmittance, and is formed of a member having a refractive index for obtaining a desired light distribution and light quantity. Further, in conventional vehicle headlamps such as incandescent lamps and halogen lamps, the condenser lens 14 was heat-resistant glass or the like having excellent heat resistance in order to prevent heat from the light source. Since heat does not reach from the light source, an inexpensive glass material can be used, so that cost can be reduced.

  3 to 5 schematically show the light propagation of the vehicular lamp shown as an embodiment of the present invention. FIG. 3 is an explanatory view showing the cross-sectional position of the vehicular light source unit, and FIG. 3 is an explanatory view schematically showing light propagation in the AA cross-sectional view of FIG. 3, and FIG. 5 is an explanatory view schematically showing light propagation in the BB cross-sectional view of FIG. Note that the cross section schematically showing the light propagation of the vehicle light source unit is merely an example. In the following description, in FIG. 4, the upper direction is the upper direction, the lower direction is the lower direction, the left direction is the front, the right direction is the rear, and the direction perpendicular to the paper surface is the left-right direction. In FIG. 5, the upper direction is assumed to be forward, the downward direction is assumed to be rear, the left direction is assumed to be left, the right direction is assumed to be right, and the direction perpendicular to the paper surface is assumed to be vertical.

  In FIG. 3, a cross section about the vertical direction at the center of the light source unit 10 of the vehicular lamp 100 is taken as an AA cross section, and a cross section about the horizontal direction at the center of the light source unit 10 of the vehicular lamp 100 is taken as B- B cross section. In the following description, it is assumed that the internal reflector 6 in the AA cross section is 6a, the sub reflector 12 is 12a, the internal reflector 6 in the BB cross section is 6b, and the sub reflector 12 is 12b.

  In FIG. 4, the internal reflector 6a has a curved surface along an ellipse 18a (imaginary line) with the first focus 16a on the rear side and the second focus 17a on the front side. The sub reflector 12a also has a curved surface along the same ellipse 18a. The first focus 16a is disposed so as to be the center of the phosphor, and the shade 13 is disposed below the second focus 17a. Further, on the optical axis 19a of the ellipse 18a connecting the first focal point 16a and the second focal point 17a, the center of the cold cathode electron source 1, the focal point of the internal reflector 6a, the focal point of the sub-reflector 12a, and the focal point of the condenser lens 14. Is arranged.

  Of the light emitted from the phosphor 5 at the first focal point 16 a, the reflected light reflected by the internal reflector 6 a and the sub-reflector 12 a is condensed on the shade 13 at the second focal point 17 a and reflected by the shade 13. A part of the light is shielded to form a light distribution pattern.

  In FIG. 5, the internal reflector 6 b has a free curved surface with respect to the front frame 3 based on an elliptical surface with the first focus 16 b on the rear side and the second focus 17 b on the front side. The sub-reflector 12b also has a free curved surface based on the same ellipsoidal surface. The ellipsoid has a first focal point 16 b at the center of the phosphor and a second focal point 17 b substantially above the shade 13. In addition, the center of the cold cathode electron source 1, the focal point of the internal reflector 6b, the focal point of the sub-reflector 12b, and the focal point of the condenser lens 14 are arranged on the optical axis 19b connecting the first focal point 16b and the second focal point 17b. ing. The condensing lens 14 condenses the reflected light from the reflecting surface of the internal reflector 6 in front of the vehicle. The condenser lens 14 is a convex lens of an aspheric lens. The front side of the condenser lens 14 forms a convex aspheric surface, while the rear side of the condenser lens 14 forms a flat aspheric surface (plane). The condenser lens 14 has a lens focal point (a meridional image plane that is a focal plane on the object space side). The focal point of the condenser lens 14 is located at or near the second focal point 17b of the reflecting surface. The optical axis of the condenser lens 14 and the optical axis 19b of the reflecting surface are coincident or almost coincident. It should be noted that the optical axis of the condenser lens 14 and the optical axis 19b of the reflecting surface may be shifted left and right.

  Of the reflected light reflected by the internal reflector 6b and the sub-reflector 12b, the reflected light that does not interfere with the shade 13 is condensed near the center of the condenser lens 14, as shown in FIG. The light is adjusted by the condenser lens 14. Thereby, the light distribution which expands in the left-right direction (vehicle vehicle width direction) can be formed. Therefore, the range irradiated by the vehicular lamp 100 can be expanded to a desired range.

  The reflecting surface of the internal reflector 6 is a reflecting surface based on an ellipse, such as a rotating ellipsoid or a free-form surface (NURBS surface) based on an ellipse (the vertical cross section in FIG. 4 is an ellipsoid, and The horizontal cross section of FIG. 5 comprises a parabolic surface or a reflective surface forming a deformed parabolic surface. For this purpose, the reflecting surface of the internal reflector 6 has a first focal point and a second focal point (a focal line on the horizontal section). The sub-reflector 12 has a free curve obtained by combining elliptical lines having the same elliptical focal point as the internal reflector 6.

  In the light source unit 10 of the present embodiment, the shape of the hole of the reflector 6a is a rectangular shape having a long left and right direction in order to obtain a laterally spread light distribution, but there is no particular limitation. The shape of the hole of the reflector 6a is long in the left-right direction, but may be an ellipse. Further, the cold cathode electron source 1 or the phosphor 5 may have the same shape as the hole of the reflector 6a.

  Thus, according to the present embodiment, the light emitted from the fluorescent material toward the back surface side of the phosphor 5 can be effectively utilized by reflecting the light in the light emitting direction (front surface side) by the internal reflector 6. . Moreover, the irradiation range can be expanded.

  Further, according to the present embodiment, the lossless gate electrode 2 can extract electrons from the cold cathode electron source 1 and further accelerate the electrons, so that it collides with the phosphor 5 disposed on the ITO film 4. The kinetic energy of electrons can be increased. Furthermore, since the lossless gate electrode 2 can control the region of the first electric field, electrons extracted from the cold cathode electron source 1 efficiently collide with the phosphor 5 disposed on the ITO film 4. Can be made. Therefore, it is possible to effectively obtain the amount of light from the phosphor 5 with a small amount of voltage. Further, the light emitted from the fluorescent material toward the back surface side of the phosphor 5 can be effectively utilized by being reflected by the internal reflector 6 in the light emitting direction on the front surface side.

  In addition, according to the present embodiment, the internal reflector 6 is a free-form surface based on an ellipsoidal surface of light emitted from the phosphor 5 and directed toward the light emission direction on the rear and side sides of the phosphor 5. With this reflective surface, the light distribution in the light emitting direction (front side) can be reflected so as to be substantially parallel light in the vertical direction and diffused light in the horizontal direction. Therefore, it can be effectively used as a vehicular lamp having a light quantity and a light distribution range defined by laws and regulations.

  Further, in the present embodiment, the light diffused on the front side of the phosphor 5 can be reflected by the sub-reflector 12 in the light emitting direction (front side) and effectively used. For this reason, the amount of light in the light emitting direction (front side) increases, so that the light source output can be suppressed, and the power consumption can be reduced.

  Moreover, according to this embodiment, the width | variety of the projection direction side of the light source unit 10 can be thinned, and it becomes possible to reduce in size also as a vehicle lamp. Furthermore, since the distance between the cold cathode electron source 1 and the ITO film 4 is short, a large kinetic energy can be given to electrons extracted from the cold cathode electron source 1 with a small applied voltage, so that power consumption can be reduced. . Further, when the inside of the frame body 7 is evacuated, the condensing lens 14 is not integrated and the shape of the frame body 7 can be simply configured, so that the workability is good and the manufacturing cost can be reduced. Further, the light emitted from the phosphor 5 by the condenser lens 14 and the light reflected by the internal reflector 6 and the sub-reflector 12 can be effectively irradiated forward, and the shade 13 can provide a plurality of desired light distributions. You can switch patterns. Therefore, it is possible to satisfy the light quantity and the light distribution range defined by laws and regulations as a vehicle headlamp.

  Therefore, according to this embodiment of the present invention, a small and sufficient amount of light can be obtained by effectively utilizing the light emitted from the phosphor 5 and effectively utilizing the light emitted from the phosphor 5. Thus, a field emission lamp type vehicle lamp 100 capable of reducing power consumption can be provided.

  The preferred embodiments of the present invention have been described above. However, the present invention can be variously modified and changed without departing from the concept of the claims.

  Further, in the present embodiment, one light source unit 10 is provided with one shade 13 and a condensing lens 14, but one light source unit 10 is provided with one shade 13 and a light collecting unit 14. The structure provided with the optical lens 14 may be sufficient.

  Moreover, in the said embodiment, although the frame 7 of the light source unit 10 has the shape of a rectangular parallelepiped, it is not specifically limited. You may follow the shape of a cylinder or an elliptical column, or the shape of a desired vehicle lamp.

It is an external appearance perspective view of the light source unit for vehicles shown as an embodiment of the present invention. It is sectional drawing of the vertical direction (up-down direction) of FIG. It is explanatory drawing which shows the cross-sectional position of the light source unit for vehicles shown as embodiment of this invention. It is AA sectional drawing which shows typically propagation of the light of the light source unit for vehicles shown as embodiment of this invention. It is BB sectional drawing which shows typically propagation of the light of the vehicle light source unit shown as embodiment of this invention. It is sectional drawing of the conventional vehicle lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cold cathode electron source 2 Lossless gate electrode 3 Front side frame 4 ITO film 5 Phosphor 5a Phosphor center 6 Internal reflector 7 Frame 10 Light source unit 12 Sub reflector 13 Shade 14 Condensing lens 16 1st focus 17 2nd Focus 18 Ellipse 19 Optical axis 100 Vehicle lamp

Claims (3)

A frame,
A cathode and an anode provided in the frame and spaced apart from each other to form a first electric field;
A phosphor that is disposed at a position where a first electric field is formed in the frame, and is excited by electrons emitted from the cathode toward the anode, and a phosphor emits light;
A first reflector disposed on the back side of the phosphor in the frame;
A control electrode arranged to sandwich the first electric field and forming a second electric field to control a region of the first electric field;
A second reflector disposed on the front side of the phosphor outside the frame;
A vehicular lamp characterized by comprising: The first reflector has a free-form surface based on an ellipsoid that forms reflected light that is substantially parallel to the vertical direction and diffuses in the horizontal direction.
The vehicular lamp according to claim 1, wherein the second reflector has an aspect that is an extension of a free aspect of the first reflector. A condenser lens that transmits the light emitted from the phosphor, the light reflected by the first reflector and the second reflector, and irradiates the light forward;
The vehicular lamp according to claim 1, further comprising a shade that is disposed between the phosphor and the condenser lens and switches a light distribution pattern.

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