EP2475930B1 - Lamp unit - Google Patents

Description

Technical area

The invention relates to a lamp unit according to the preamble of claim 1.

State of the art

Such a lamp unit can be used in principle in a variety of single-ended lamps. However, the main application area is likely to be in lamp units for vehicle headlights. A lamp unit for such motor vehicle headlights is for example in the EP 1 605 490 A2 , of the DE 10 2005 009 902 A1 and the US 2002/0003391 described.

In these known solutions, the lamp unit has a discharge lamp, as sold for example under the product name "Xenarc ™". This high-pressure discharge lamp has a one-part or multi-part lamp cap, by way of which it can be inserted into a socket of a reflector of a motor vehicle headlight. In order to align the lamp in the reflector and to prevent incorrect assembly of different lamp types, one or more referencing and Kodierausnehmungen are formed on a Referenzierring the socket, which cooperate with corresponding projections on the socket of the reflector, so that the lamp only in a predetermined relative position can be used with reference to the version. Furthermore, this referencing prevents lamps of an unintentional type from being used in a vehicle headlight.

In the conventional solutions, a plurality of radially projecting additional elements which are part of the headlamp are additionally arranged on the base of the high-pressure discharge lamp, on which mechanical components, for example clamps, brackets, coupling cages or the like, engage around the base in the socket of the reflector set.

A disadvantage of these solutions is that such lamp units are constructed for a relatively complex, since the additional components must be provided for fixing the position. On the other hand, the assembly effort is increased by the attachment of additional components.

Presentation of the invention

In contrast, the invention has for its object to provide a simply constructed and easy to install lamp unit.

This object is achieved by a lamp unit with the features of claim 1. Special advantageous embodiments of the invention are described in the dependent claims.

According to the invention, the lamp unit is designed with a lamp which is inserted in a reflector and has a base with a reference ring on which at least one referencing surface is formed. This cooperates with a corresponding referencing element of a version of the reflector. The lamp is connected to the reflector by means of a detachable bayonet catch.

By using a bayonet closure, the lamp can be connected directly to the reflector, so that the complex assembly of the additional components, such as the above-described brackets, brackets or throwaway cages can be omitted and thus both the device complexity and the assembly cost is reduced.

In a preferred embodiment of the invention, the bayonet closure has formed on the reference ring, circumferentially opening free cuts, which are assigned from an inner peripheral surface of the socket radially projecting bayonet cams. These are when inserting the lamp in the reflector in coverage with the cutouts and engage behind the reference ring in the locked state.

On the inner peripheral surface of the socket offset from the bayonet cams bearing pins can be formed for the reference ring.

It is preferred if reference studs are formed on a support pin-side annular surface of the reference ring, which can be brought in defined contact with said support pins.

For unambiguous determination of the locking position, in a variant of the invention, stop cams are formed on the outer circumference of the base, onto which the bayonet cams accumulate during connection.

In a further preferred embodiment, a stop cam on the inner peripheral surface is formed approximately at a same axial height as the support pins and has an abutment portion extending approximately in a longitudinal direction of the reflector toward the bayonet cams and spaced from the inner circumferential surface.

When inserting the lamp, the stopper portion dips into a locking groove of the reference ring, wherein when locking a Nutrandabschnitt the locking groove runs onto the stop cam.

The locking groove can be formed with little device complexity as a recess in the side walls of an open cut.

For locking the lamp cap in the circumferential direction of the stopper portion may be engaged behind in a locking position of the lamp by a formed on a base surface of the free-cutting locking projection.

In order to enable a substantially backlash-free locking of the lamp cap in the reflector, the latching groove can be configured such that in the locking position the reference ring is stretched over the stop cam against pretensioner elevations formed on the inner circumferential surface approximately opposite the stop cam.

In a further advantageous embodiment of the invention, a radial recess in the inner peripheral surface is introduced approximately between the bayonet cams and the support pin. In this an elongated spring hook is arranged approximately along an inner diameter of the inner peripheral surface extending. In the area of a bayonet cam, a hook portion of the spring hook projects radially inwardly, on which a portion of the free-cutting of the reference ring runs when locking.

Advantageously, a spring shaft of the spring hook is designed such that it biases the reference ring in the locking position against the formed on the inner peripheral surface approximately opposite the spring hook Vorspannerhöhungen.

As already mentioned, the additional components for fixing the position of the lamp in the reflector are unnecessary in the lamp unit according to the invention - should a lamp according to the invention, however, be used in a conventional reflector, this can be carried out in a conventional manner with additional radial pins for supporting the additional components. This variant is then optionally used in conventional versions as well as in versions according to the invention.

In a simple embodiment with optimal fixation of the lamp in the reflector three bayonet cams on the version of the reflector and three free cuts are made on the reference ring of the lamp. In principle, the cutouts on the socket of the reflector and the bayonet cams on the base could also be executed in kinematic reversal or according to the reversal principle.

In a simple embodiment, the free cuts extend approximately to the outer circumference of a base sleeve from which the reference ring projects radially.

According to a variant of the invention, the free cuts are made approximately rectangular.

Preferably, three reference knobs and three support pins are provided to ensure the frontal positioning of the lamp in the reflector.

The lamp unit is preferably designed with a high-pressure discharge lamp for a motor vehicle headlight.

Brief description of the drawings

• Fig. 1 eine dreidimensionale Prinzipdarstellung einer erfindungsgemäßen Lampeneinheit gemäß einem ersten Ausführungsbeispiel;
• Fig. 2 eine Lampe der Lampeneinheit aus Figur 1 gemäß dem ersten Ausführungsbeispiel;
• Fig. 3 eine Vorderansicht der Lampe aus Figur 2 gemäß dem ersten Ausführungsbeispiel;
• Fig. 4 eine Rückansicht der Lampe aus Figur 2 gemäß dem ersten Ausführungsbeispiel;
• Fig. 5 eine Einzeldarstellung eines Reflektors der Lampeneinheit aus Figur 1 gemäß dem ersten Ausführungsbeispiel;
• Fig. 6 eine Rückansicht der Lampeneinheit aus Figur 1 gemäß dem ersten Ausführungsbeispiel;
• Fig. 7 eine Einzeldarstellung des Reflektors der Lampeneinheit gemäß einem zweiten Ausführungsbeispiel;
• Fig. 8 eine Einzeldarstellung eines Referenzrings gemäß dem zweiten Ausführungsbeispiel;
• Fig. 9 in einer Rückansicht den Reflektor und den Referenzring gemäß dem zweiten Ausführungsbeispiel;
• Fig. 10 in einer Rückansicht den Reflektor und den Referenzring gemäß dem zweiten Ausführungsbeispiel;
• Fig. 11 eine Einzeldarstellung des Reflektors der Lampeneinheit gemäß einem dritten Ausführungsbeispiel;
• Fig.12 eine Einzeldarstellung des Reflektors gemäß dem dritten Ausführungsbeispiel;
• Fig. 13 in einer Rückansicht den Reflektor und den Referenzring gemäß dem dritten Ausführungsbeispiel; und
• Fig. 14 in einer Rückansicht den Reflektor und den Referenzring gemäß dem dritten Ausführungsbeispiel.

The invention will be explained in more detail below with reference to preferred embodiments. Show it:

• Fig. 1 a three-dimensional schematic diagram of a lamp unit according to the invention according to a first embodiment;
• Fig. 2 a lamp of the lamp unit FIG. 1 according to the first embodiment;
• Fig. 3 a front view of the lamp FIG. 2 according to the first embodiment;
• Fig. 4 a rear view of the lamp FIG. 2 according to the first embodiment;
• Fig. 5 a single representation of a reflector of the lamp unit FIG. 1 according to the first embodiment;
• Fig. 6 a rear view of the lamp unit FIG. 1 according to the first embodiment;
• Fig. 7 an individual view of the reflector of the lamp unit according to a second embodiment;
• Fig. 8 a single representation of a reference ring according to the second embodiment;
• Fig. 9 in a rear view of the reflector and the reference ring according to the second embodiment;
• Fig. 10 in a rear view of the reflector and the reference ring according to the second embodiment;
• Fig. 11 a detail view of the reflector of the lamp unit according to a third embodiment;
• Figure 12 a detail view of the reflector according to the third embodiment;
• Fig. 13 in a rear view of the reflector and the reference ring according to the third embodiment; and
• Fig. 14 in a rear view of the reflector and the reference ring according to the third embodiment.

Preferred embodiment of the invention

FIG. 1 shows a three-dimensional view of a lamp unit 1 according to the invention with a used in a reflector 2 of a motor vehicle headlamp high-pressure discharge lamp 4. This can be, for example, a metal halide high-pressure discharge lamp with an electrical power consumption of about 25 W or a D1 to D4 lamp. Such high-pressure discharge lamps are known from the prior art, for example EP 1 605 490 A2 or the EP 0 786 791 B1 Well known, so that only the essential elements for understanding the invention components are explained and reference is otherwise made to the cited prior art.

The peculiarity of in FIG. 1 illustrated lamp unit 1 is that the reflector 2 and the high-pressure discharge lamp 4 are connected to each other by means of a bayonet fitting 6, which is dispensed with in contrast to conventional solutions to additional components such as brackets, stirrups or cages.

FIG. 2 This has a, not visible here discharge vessel with an interior, in the two diametrically arranged electrodes protrude, connected via melted into the discharge vessel metal foil, each with a power supply 10 and another, not shown power supply are. That in the FIGS. 1 and 2 invisible, indicated by the reference numeral 8 discharge vessel is received in an outer bulb 9, which is also made of quartz glass and optionally provided with an ultraviolet radiation absorbing coating.

The in the FIGS. 1 and 2 visible external power supply 10 is connected to a socket 12 at a circumferentially arranged contact ring 14. The axial power supply, not shown, is connected to a central contact pin 16 of the base 12 (see Fig.2 ) contacted. In the interior of the discharge vessel 8 an ionizable filling is added, which consists for example of high purity xenon gas and a plurality of metal halides.

In the usual manner multi-part socket 12 is embedded with a protruding to the outer bulb 9 out spring tongues 18 executed metal ring. The designed as welding flags spring tabs 18 are one arched onto the outer bulb 9 supporting cuff 20 and connected thereto, for example by welding. By the four spring tongues / welding lugs 18 and the corresponding executed support sleeve 20, the high-pressure discharge lamp 4 is reliably position-centered in the axial direction. For further details of the structure of the base 12, reference is made to the above-mentioned prior art.

The FIG. 3 shows a front view and FIG. 4 a rear view of the high pressure discharge lamp 4 according to FIG. 2 , Accordingly, the base 12 has a base sleeve 22, from which a reference ring 24 projects circumferentially in the radial direction. The remote from the reference ring 24 end portion of the base sleeve 22 via a radial step in a contact collar 26, on the outer circumference of the circumferential contact ring 14 is formed and which surrounds the central contact pin 16 at a distance.

In the region of the radial step to the contact collar 26 are on the outer circumference of the base sleeve 22 two (see FIG. 4 ) provided diametrically opposed radial pins 28 which serve to bayonet an electrical connector. In the illustrated embodiment, these two radial pins 28 have no function.

The formed on the base sleeve 22 reference ring 24 has at least one coding groove 30, which is designed in the illustrated embodiment as a semi-circular recess. By this coding groove or coding grooves is ensured that only a certain type of high-pressure discharge lamp 4 can be used in a predetermined relative position in the motor vehicle headlight. In addition to the coding groove 30 three uniformly distributed on the circumference free cuts 32 a, 32 b, 32 c are executed on the reference ring 24, which in the illustration in accordance with Figures 3 and 4 have an approximately rectangular cross-section and extending from the outer periphery of the reference ring 24 up to the base sleeve 22.

According to FIG. 3 are on an outer piston-side end face 34 of the reference ring 24 three opposite the cutouts 32 and the coding groove 30 offset, also uniformly distributed around the circumference reference knobs 36a, 36b, 36c provided which protrude slightly from the end face 34 in the axial direction and in contact with later explained elements of Reflectors are brought to set the axial position of the high pressure discharge lamp in the reflector.

As shown in FIG. 3 the external power supply 10 is connected to a contact plate 38, which also in the bottom view according to FIG. 4 is visible and in turn contacted with the contact ring 14. How out FIG. 4 can be seen, 24 are each arranged adjacent to one of the free cuts 32 stop cam 42a, 42b, 42c, which in the illustration according to FIG FIG. 4 extending from the rear end face 40 out to the viewer. As will be explained in more detail below, these stop cams 42a, 42b, 42c limit the relative rotation between the discharge lamp 4 and the reflector 2.

Two of these stop cams 42a, 42b are also shown in the illustration FIG. 2 visible, noticeable. Accordingly, extend the stop cams 42 away from the outer periphery of the base sleeve 22 to the outer periphery of the reference ring 24 and extending in the axial direction to the rear end face 40 (see FIG. 2 ).

FIG. 5 shows a three-dimensional representation of the reflector 2 of the lamp unit 1 according to FIG. 1 , This reflector has an in FIG. 1 visible, designed with a view to optimal beam alignment reflection surface 44 and a socket 46, which is designed approximately as a cylindrical portion. On an inner peripheral surface 48 of the socket 46 are three uniformly distributed on the circumference, lying on the same pitch circle as the cutouts 32 bayonet cams 50a, 50b, 50c formed projecting inwards, embraced by the socket 46 opening and their geometry in about that the free cuts 32 corresponds. Offset to these bayonet cams 50 three bearing pins 52a, 52b, 52c are provided on the inner peripheral surface 48, which lie on the same pitch circle as the reference knobs 36. The diameter of the inner circumferential surface 48 corresponds approximately to the outer circumference of the reference ring 24.

To insert the high-pressure discharge lamp 4 into the reflector 2, first the free cuts 32a, 32b, 32c are brought into register with one of the bayonet cams 50a, 50b, 50c and the lamp is then lighted from behind (view from FIG Fig. 5 ) used in the version 46. The bayonet cams 50a, 50b, 50c penetrate through the free cuts 32a, 32b, 32c and the front end face 34 (FIG. FIG. 3 ) runs on the corresponding contact surfaces of the support pin 52.

In a subsequent assembly step, the high-pressure discharge lamp 4 with respect to the reflector 2 to the right in a clockwise direction (view FIG. 6 ), so that the bayonet cams 50a, 50b, 50c engage behind the reference ring 24 and run onto the adjacent stop cams 42a, 42b and 42c after a predetermined angle of rotation. In this rotational angle position, the three reference knobs abut on the front end face 34 of the reference ring 24 on the adjacent end faces of the three support pins 52a, 52b, 52c for adjusting the axial position. In this mounting position, the discharge lamp 4 is clamped in the axial direction between the support pin 52 and the bayonet cams 50 and fixed in position in the circumferential direction by the bezel 24 surrounding the bezel 46, so that a reliable relative positioning between the reflector 2 and high-pressure discharge lamp 4 is ensured with extremely simple construction.

In the illustrated embodiment, the single or multi-part base 12 is made of a suitable plastic, wherein the contact elements described are partially encapsulated. The reflector is provided with a suitable coating and also made of plastic.

In FIG. 6 is in a three-dimensional representation of the reflector 2 of the lamp unit 1 from FIG. 1 shown according to a second embodiment. On the inner peripheral surface 48 of the reflector 2, a ring 54 is formed approximately at a same axial height as the support pin 52. The inner diameter of the ring 54 is approximately between the diameter of the inner peripheral surface 48 and the inner diameter of the support pin 52. On the ring 54 is Formed between the two support pins 52a and 52b about the region of the bayonet cam 50a, an elongated stop cam 56 which extends approximately in the longitudinal direction of the reflector 2. A stop section 58 of the stop cam 56 projects in the longitudinal direction towards the bayonet cam 50a.

The stop cam 56 serves to limit the relative rotation between the discharge lamp 4 and the reflector 2 FIG. 1 , For this purpose, the in FIG. 8 shown reference ring 24 of the base 12 FIG. 12 according to the second embodiment, a cutout 60 with a locking groove 62, in the upon insertion of the reference ring 24 in the reflector 2 of the stop cam 56 with the stopper portion 58 from FIG. 7 dips. To form the latching groove 62, a respective recess 68 or 70 is introduced into a respective side wall 64 and 66 of the cutout 60. Centered between the recesses a locking projection 72 is formed on a base surface of the recess 60, which in a locking position of the reference ring 24, the stopper portion 58 of the stop cam 56 from FIG. 7 engages, which is explained in more detail below.

FIG. 9 shows the reflector 2 together with the reference ring 24 used in this according to the second embodiment. For the sake of simplicity, as in FIG. 8 only the reference ring 24 without the base 12 from FIG. 2 shown. In the in FIG. 9 shown position of the reference ring 24 has been used in the axial direction in the socket 46 in which the cutouts 32b, 32c and 60 in register with the bayonet cams 50a, 50b, 50c and the coding groove 30 in register with the corresponding Referencing of the reflector 2 are brought into coincidence. The stop portion 58 of the stop cam 56 from FIG. 7 is doing in the in FIG. 8 right recess 70 of the locking groove 62 immersed. Will the base 12 off FIG. 2 with the reference ring 24 is now rotated to lock clockwise relative to the reflector 2, then the stopper portion 58 slides over the locking projection 72 in the in the FIG. 8 left recess 68 of the locking groove 62. This position of the reference ring 24 to the reflector 2 is in the FIG. 10 shown. It can be seen that the locking projection 72, the stop portion 58 of the stop cam 56 from FIG. 7 engages behind, whereby the reference ring 24 is locked in the circumferential direction by the stop cam 56.

The in the FIG. 8 left recess 68 of the locking groove 62 is offset slightly in the radial direction compared to the right recess 17 to the outside. The offset is used to tension the reference ring, which is explained below.

In the in FIG. 9 shown insertion position of the reference ring 24 this is approximately powerless in the socket 46. The reference ring 24, as described above, in the locking position in FIG. 10 rotated, then spans on the stop cam 56 FIG. 7 inwardly facing side surface 74 of the reference ring 24 via a bottom surface 76 of in FIG. 8 left recess 68 against the inner peripheral surface 48 of the reflector 2 in FIG. 10 , To define certain areas in which the reference ring 24 with a clamping force in FIG. 10 is acted upon, on the inner peripheral surface 48, two about the stop cam 56 oppositely arranged Vorspannerhöhungen 78, 80 are formed. These are in the axial direction formed approximately between the ring 54 and the bayonet cams 50. How out FIG. 10 it can be seen that the reference ring 24 is clamped defined defined between the two Vorspannerhöhungen 78, 80 and the stop portion 58 of the stop cam 56.

FIG. 11 shows a perspective view of the reflector 2 according to a third embodiment. The socket 46 is in this case of a rear end face 82 in the axial direction of a circle segment between the two upper in FIG. 11 arranged support pin 52a, 52b downgraded with a recess 84. This extends in the axial direction approximately to the ring 54 adjacent to the Referenzierelement 86 and in the FIG. 11 left upper support pin 52a.

From a left side surface 88 of the recess 84 projects a spring hook 90 approximately in the circumferential direction. This has an elongated spring shaft 92 and a approximately centrally of the recess 84 radially inwardly kinked hook portion 94. The spring hook 90 serves as the stop cam 56 FIG. 7 for positioning the lamp cap 12 in the circumferential direction and for clamping the reference ring 24.

In contrast to the previous embodiment, the bayonet cams 50a, 50b, 50c are formed on a separate retaining ring 96. This is attached to the reflector 2, which is in FIG. 12 it can be seen fixed to this, that the bayonet cams 50 are positioned according to the preceding embodiments.

FIG. 13 shows the reflector 2 together with the reference ring 24 of the first embodiment FIG. 4 in an insertion position. The hook portion 94 of the spring hook 90 from FIG. 11 is immersed in the upper free cut 32a of the reference ring 24. Upon rotation of the reference ring 24 in the clockwise direction, the hook portion 94 comes into abutment against a left side surface 98 of the upper recess 32a, whereby the reference ring 24 is positioned in the circumferential direction. For tightening the reference ring 24 against the Vorspannerhöhung 78, 80 from FIG. 11 via the spring hook 90, this has on the spring shaft 92 adjacent to the hook portion 94 a radially inwardly facing camber 100. This is in the immersion position in FIG. 13 arranged next to the spring hook 90 in the upper cutout 32a. Upon rotation of the reference ring 24, this slides on an outer peripheral wall 102 of the reference ring 24 and biases this against the Vorspannerhöhungen 78, 80 from FIG. 11 , The biasing force is dependent on the elasticity of the spring hook 90. This is for example made of a metallic material or manufactured in one piece by injection molding of the socket 46.

In order to clamp the reference ring 24 in the axial direction with a high biasing force, the bayonet cams 50a, 50b, 50c are made FIG. 12 bent slightly into the plane of the drawing. To a high surface pressure between the bayonet cams 50a, 50b and 50c in the FIG. 14 and reach the reference ring 24, 24 V-shaped projections 104 are formed on the bayonet cams 50 toward the reference ring.

Disclosed is a lamp unit with a high-pressure discharge lamp, which is used in a reflector, preferably a motor vehicle headlight. The lamp has a base with a reference ring, which is connected via a bayonet interface with socket of the reflector.

Claims (15)

1. Lamp unit comprising a lamp (4) which is inserted into a reflector (2) and which has a base (12) with a reference ring (24) on which at least one referencing surface (30) is formed, the said referencing surface interacting with a corresponding referencing element of a mount (46) of the reflector (2), wherein the lamp unit has a bayonet fitting (6) by means of which the lamp (4) is connected in a detachable manner to the mount (46), characterized in that the bayonet fitting (6) has clearances (32) which are formed on the reference ring (24), open out on the circumferential side and with which the radially projecting bayonet cams (50) which are provided on an inner circumferential surface of the mount (46) are associated, the said bayonet cams overlapping the clearances (32) when the lamp (4) is inserted and engaging behind the reference ring (24) during connection, and in that support pins (52) for the reference ring (24), which support pins are offset in relation to the bayonet cams (50), are formed on an inner circumferential surface (48) of the mount (46).
2. Lamp unit according to Patent Claim 1, wherein reference nubs (36) are formed on a front end surface (34) of the reference ring (24), it being possible for the reference nubs to be brought to bear on the support pins (52).
3. Lamp unit according to either of Patent Claims 1 and 2, wherein at least one stop cam (42) is formed on an outer circumference of the base (12), the bayonet cams (50) running onto the said stop cam during locking.
4. Lamp unit according to either of Patent Claims 1 and 2, wherein a stop cam (58) is formed on the inner circumferential surface (48) approximately at the same axial height as the support pins (52) and has a stop section (58) which, approximately in a longitudinal direction of the reflector (2), extends in the direction of the bayonet cams (50) and is at a distance from the inner circumferential surface (48), the said stop section entering a latching groove (62) of the reference ring (24) when the lamp (4) is inserted, and wherein a groove edge section runs onto the stop cam (56) during locking.
5. Lamp unit according to Claim 4, wherein the latching groove (62) is formed as a cutout (68, 70) in each side wall of a clearance (60).
6. Lamp unit according to Claim 5, wherein a locking projection (72) which is formed on a base surface of the clearance (60) engages behind the stop section (58) in a locking position of the lamp (4).
7. Lamp unit according to one of Claims 4 to 6, wherein the latching groove (62) is designed in such a way that, in the locking position, the reference ring (24) is tensioned against pretensioning raised portions (78, 80), which are formed on the inner circumferential surface (48) approximately opposite the stop cam (56), by means of the stop cam (56).
8. Lamp unit according to either of Patent Claims 1 and 2, wherein a radial cutout (84) is made in the inner circumferential surface (48) approximately between the bayonet cam (50) and the support pin (52), an elongate spring hook (90) which extends approximately along an inside diameter of the inner circumferential surface (48) being arranged in the said radial cutout, the said spring hook having, in the region of a bayonet cam (50a), a hook section (94) which points radially inward and onto which a clearance (32a) of the reference ring (24) runs during locking.
9. Lamp unit according to Patent Claim 8, wherein a spring shaft (92) of the spring hook (90) is designed in such a way that the said spring shaft tensions the reference ring (24) against the pretensioning raised portions (78, 80), which are formed on the inner circumferential surface (48) approximately opposite the spring hook (90), in the locking position.
10. Lamp unit according to one of the preceding patent claims, having additional radial pins (28) for an electrical plug.
11. Lamp unit according to one of Patent Claims 1 to 10, wherein three bayonet cams (50) and, accordingly, three clearances (32) are provided.
12. Lamp unit according to one of Patent Claims 1 to 11, wherein the clearances (32) extend in the radial direction approximately as far as an outer circumference of a base sleeve (22) from which the reference ring (24) radially projects.
13. Lamp unit according to Patent Claim 12, wherein the clearances (32) are of approximately rectangular design as seen in the axial direction.
14. Lamp unit according to one of Patent Claims 1 to 13, wherein three reference nubs (36) and, accordingly, three support pins (52) are provided.
15. Lamp unit according to one of the preceding patent claims, wherein the lamp is a high-pressure discharge lamp (4).

Images