GB2368200A

GB2368200A - Lamp holder with arrangement to increase airflow

Info

Publication number: GB2368200A
Application number: GB0120745A
Authority: GB
Inventors: Stephen John Smith
Original assignee: RINGTEL ELECTRONICS
Current assignee: RINGTEL ELECTRONICS
Priority date: 2000-12-22
Filing date: 2001-08-24
Publication date: 2002-04-24
Anticipated expiration: 2021-08-24
Also published as: GB2368200B; GB0031492D0; GB0120745D0

Abstract

A holder for a lamp bulb comprises an insulating housing 10 having a socket 14 for receiving a lamp bulb 26 and first, second and third terminal receiving cavities 28, 36, 38 with first, second and third electrical terminals 30, 40, 42 disposed therein. Two of the electrical terminals 40, 42 each have a slot 44, 46 receiving a lead 48 of an electrical component 50 or link, such that the component 50 or link is disposed within the housing 10 axially or longitudinally relative thereto. This arrangement creates less obstruction to airflow reducing the temperature of the holder. A slit(s) (22, Fig 3) in the housing 10 may further increase airflow. The socket 14 may comprise a number of arms (20, Fig 4) in an annular configuration.

Description

LAMP HOLDER

This invention relates to a lamp holder and, in particular, to a holder for baseless lamp bulbs used in, for example, gaming machines.

Gaming machines and the like employ a substantial number of lamps which are illuminated, simultaneously or in a predefined sequence, while the machine is in operation. Such lamps are normally held in individual lamp holders which are either mounted on or formed integrally with a backing board.

European patent application number EP-A-0701306 describes a lamp bulb holder having an insulating housing in which first, second and third electrical terminal are disposed.

The first and second terminals are provided with slots for receiving respective leads of a component, such as a diode.

The component lead receiving slots open towards a terminal receiving end of the housing. The component is inserted in the slots so that it lies across the diameter of the housing. The third terminal is then inserted in the housing and comprises two side walls and a plate which spans the side wall and lies across the component when the holder has been assembled.

The component and this plate of the third terminal, in particular, present obstructions to any airflow through the housing, which may allow relatively high ambient temperatures to build up within the housing cavity, leading to component failure and reduced efficiency.

We have now devised an arrangement which overcomes this and other problems associated with the prior art.

In accordance with a first aspect of the present invention, there is provided a holder for a lamp bulb, the holder comprising an insulating housing having a socket for receiving a lamp bulb and first, second and third terminal receiving cavities, and first, second and third electrical terminals disposed in said first, second and third terminal receiving cavities, two of said electrical terminals each having a slot receiving a lead of an electrical component or

link which is disposed within said housing axially or longitudinally relative thereto.

The first aspect of the present invention also extends to a method of assembling a lamp bulb holder, the method comprising the steps of providing an insulating housing having a socket for receiving a lamp bulb and first, second and third terminal receiving cavities, inserting a first electrical terminal in said first terminal receiving cavity, inserting the leads of an electrical component or link into slots provided in second and third electrical terminals respectively and inserting the assembly comprising the second and third electrical terminals and said component or link into said housing such that said second and third terminals are disposed in said second and third terminal receiving cavities respectively and said electrical component or link is disposed within said housing longitudinally relative thereto.

In accordance with a second aspect of the present invention, there is provided a holder for a lamp bulb, the holder comprising a housing having a main body for receiving a plurality of electrical terminals and a socket for receiving a lamp bulb, said holder having at least one slit or opening which extends from said socket along at least a portion of the outer wall of the main body, so as to permit airflow into or through said housing.

In accordance with a third aspect of the invention, there is provided a holder for lamp bulb, the holder comprising a housing having a main body for receiving a plurality of electrical terminals, and a socket for receiving a lamp bulb, the socket comprising a plurality of arms arranged in generally annular configuration, all of said arms being of substantially equal length.

The characterising features of the lamp holder of the first and second aspects of the present invention are intended primarily to substantially improve airflow into the cavity or cavities in which the electrical terminals are disposed. In

the case of the first aspect of the present invention, by having the electrical component or link disposed longitudinally relative to the housing, there is less obstruction to airflow through the housing than in the case where the component or link is disposed across the cavity, as in European patent application number EP-A-0701306. Further, the slit or opening provided in the second aspect of the present invention increases airflow into the cavity or cavities in which the electrical terminals are disposed and past the electrical component or link, if one is provided. Airflow can be further facilitated if an air output aperture is also provided in the main body of the housing adjacent the cavity or cavities in which the electrical terminals are disposed, such that air can flow through the holder, past the electrical terminals (any component or link therein) and out into the machine in which the holder is mounted, thereby substantially reducing or eliminating high ambient temperatures occurring within the holder.

High ambient temperature can cause life reduction due to contaminants being released into the lamp from the glass bulb. Smaller size, higher wattage lamps are most likely to be affected because they have higher bulb temperature under normal conditions. If the ambient temperature in which a lamp is operating exceeds 95 degrees Celsius, it is likely that the internal bulb wall temperature will exceed 100 degrees Celsius, and minute quantities of water vapour may then start to out-gas into the lamp. Dissociation of the water vapour occurs around the hot filament and oxides of tungsten and free hydrogen are formed. In the cooler regions of the lamp near the bulb wall, the free hydrogen reduces the tungsten oxides and tungsten is deposited on the glass. The water vapour re-appears by recombination of hydrogen and oxygen, and the cycle is repeated. This is known as the'water cycle'which causes reduction of life by increasing the rate of loss of tungsten from the filament and causes a fall in light output due to bulb

blackening.

It should also be noted that the lamp itself is a heat source which can raise its own environmental temperature, particularly if encapsulated or burning in a confined space.

Thus, in accordance with the second aspect of the present invention, it is clearly advantageous to maximise ventilation, thereby enabling the operation of lamps in ambient temperatures of up to 125 degrees Celsius, without significant loss of life.

The arrangement defined in terms of the third aspect of the present invention enables the socket of the lamp holder to be made shorter than in prior art arrangements, thereby reducing the overall length of the lamp holder. Holders of this type are generally mounted in a plastic board having a plurality of vacuum formed pockets in which the holders are retained. The shorter body length enabled by the third aspect of the present invention allows the vacuum formed pocket in which it is mounted to be made shallower than in prior art arrangements. This allows greater draft angles to be used on a pocket of any given size, and benefits the tool making process by reducing the requirement for a female tool component. Further, the quality of the pocket moulding is increased because thinning is reduced, i. e. the wall of the pocket can be made thicker.

In all aspects of the present invention, the housing is preferably of moulded rigid plastics material.

The housing preferably comprises first, second and third terminal receiving cavities for receiving first, second and third electrical terminals, two of said electrical terminals having spring contact beams, designed to accommodate variations in lamp bulb contact alignment, which extend into the socket or neck to engage a respective contact of a lamp bulb retained therein, when in use. Lamp bulb contacts are liable to be misaligned either in manufacture or transit.

The end of the housing opposite to the end having the socket, hereinafter referred to as the"terminal receiving

end", is preferably provided with slots for receiving power supply leads, when in use. At least two of said electrical terminals are preferably provided with corresponding power supply lead receiving slots which open towards the terminal receiving end of the housing.

The slots for receiving the component or link leads preferably open towards a side wall of the housing.

The electrical component may be a diode. The function of such a diode is an integral component in a lamp multiplexing system. Multiplexing is a method that many lamps, say 256, can be switched by a small number of transistors. (e. g. 16 x 16), i. e. a total of 32 transistors switching 16 rows and 16 columns.

One strobing method would be 16 strobes of one millisecond each. This means that the 256 lamps are scanned in 16 Ms. When the lamps are multiplexed, the applied voltage is always higher than the nominal voltage of the lamps, but the duration is short (e. g. 1 mS).

Alternatively, an electrical wire link may be provided between two of the electrical terminals to enable direct drive of the lamp. Direct drive means to just present a voltage (say 12V) onto a 12V lamp and the diode described above would be replaced by a wire link of similar wire diameter to the diode wire inserted in the component receiving slots.

An exemplary embodiment of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is an end view of the terminal receiving end of a lamp held according to an exemplary embodiment of the present invention; Figure 2 is a cross-sectional side view of the lamp holder of Figure 1; Figure 3 is a side view of the lamp holder of Figure 1; Figure 4 is an end view of the bulb receiving or socket end of the lamp holder of Figure 1;

Figure 5 is the view of the lamp holder of Figure 4, including a bulb ; Figure 6 as a side view of a wire insertion tool for attaching supply leads to the lamp holder of Figures 1 to 5; Figure 7 is an end view of the wire insertion tool; and Figure 8 is a cut-away side view showing the wire insertion tool in use.

Referring to Figures 1 and 2 of the drawings, a lamp holder according to an exemplary embodiment of the invention comprises a generally annular or tubular housing 10 of moulded rigid plastics material.

The housing 10 has a narrowed portion 12 at one end from which extends a generally tubular neck or socket 14, which holds an elongate lamp bulb 26 in use.

The opposite end of the housing 10 to the neck 14 will be referred to herein as the terminal receiving end 15.

Although generally tubular, the neck 14 actually comprises a plurality of circumferential fingers 18. Referring in particular to Figure 4 of the drawings, the fingers 18 are arranged in two sets of three, 24 on diametrically opposite sides of the neck 14, with two diametrically opposed, wider central posts or arms 20 there between. Referring additionally to Figure 3 of the drawings, the slits 22 defining one of the arms 20 extend a substantial distance along the longitudinal wall of the main body 10 of the housing.

This provides air inlet which permits substantial airflow through the housing and allows the neck 14 to be substantially shorter in length than in prior art designs.

The provision of two sets of three pins or fingers 24 (as opposed to a single resilient neck portion) gives greater flexibility to the neck 14 such that the bulb 26 is held securely within the holder, particularly when the entire lamp unit has been assembled and is inserted in the back board (not shown) of a gaming machine or the like. However, as shown in Figure 5 of the drawings, there is a gap 100 between the

fingers 24 of the neck 14 and the outer wall of the bulb 26 when the holder is in use, to allow greater ventilation around the bulb 26.

Referring back to Figures 1 and 2 of the drawings, the inner cavity of the generally tubular housing 10 comprises a first terminal receiving cavity 28 for receiving a first electrically conductive terminal 30. One end of the first terminal 30 is provided with a spring contact beam 32 which extends into the neck 14 and engages one contact of a bulb 26 retained therein, when in use. The other end of the first terminal 30 is provided with a slot 34 which opens towards the terminal receiving cavity 28 and is of the housing 10 and is for receiving a first supply lead (not shown) for supplying power to the bulb 26, when in use. When the supply lead is pushed into the supply lead receiving slot 34, the edges of the slot cut into the insulating covering thereon to contact the conductive wires therein.

The inner cavity of the housing 10 also defines second and third terminal receiving cavities 36,38 for receiving second and third electrically conductive terminals 40, 42 respectively. Each of the second and third terminals 40,42 comprise component lead receiving slots 44,46 which, when the device is assembled, open towards the inner wall of the housing 10.

During assembly, the first terminal 30 is inserted in the first terminal receiving cavity 28. The leads 48 of a diode 50 are inserted one into each of the component lead receiving slots 44,46 and the assembly comprising the diode 50 and the second and third terminals 40,42 is inserted into the housing 10. One end of the second terminal 40 is provided with a second spring contact beam 52 which extends into the neck 14 and engages the second contact of a bulb 26, when in use.

The third terminal 42 is provided with a second supply lead receiving slot 54 which opens towards the terminal

receiving end 15 of the housing 10. Thus, in use, a complete circuit is provided from the third terminal 42 through the diode 50 to the second terminal 40 and through the bulb 26 to the first terminal 30.

The lamp bulb 26 is obstructed from incorrect insertion into the holder by two opposed protrusions 56 which extend into the central cavity of the bulb holder. This allows for the lamp bulb 26 to be inserted into the cavity only in a direction that will ensure correct contact between the lamp bulb contacts 58 and 59 and the lamp bulb holder contacts 32 and 52. The protrusions 56 extending into the cavity are further dimensioned to prevent the lamp bulb 26 from being inserted too far into the central cavity of the holder.

Once the holder is assembled, the lamp bulb 26 is inserted and retained in the neck 14 and the terminal receiving end 15 is inserted in one of a plurality of vacuumed formed receiving cavities in a back board of a gaming machine or the like.

A wire insertion tool, such as the pneumatic tool shown in Figures 6 to 8, is preferably used to attach a pair of sheathed supply leads 70,72 to the holder, by first laying the leads laterally across the terminal receiving end of the holder with each lead between each pair of slots 34 and 54, and then pressing the head of the tool against the leads, such that a pair of pivoting catches 58 on opposite sides of the tool engage respective lugs 60 on the sides of the holder to retain the holder in place, whilst a plunger 62 of the tool extends forwards from the tool to press the wires into their respective slots (as shown in Figure 8).

As can be seen in detail in Figure 7, the leading surface of the plunger 62 is formed with four pairs of fingers 64, each pair of fingers, e. g. 66,68, being arranged to press against the surface of an underlying lead, on opposite sides of a respective receiving slot 34 or 54, to drive the lead into that slot, the sheathing of the lead being severed by the opposed surface of the slot as the lead is inserted, to form a connection.

An embodiment of the present invention has been described above by way of example only and it will be apparent to a person skilled in the art that modifications and variations can be made without departing from the scope of the invention.

Claims

1) A holder for a lamp bulb, the holder comprising an insulating housing having a socket for receiving a lamp bulb and first, second and third terminal receiving cavities, and first, second and third electrical terminals disposed in said first, second and third terminal receiving cavities, two of said electrical terminals each having a slot receiving a lead of an electrical component or link which is disposed within said housing axially or longitudinally relative thereto.

2) A holder for a lamp bulb as claimed in Claim 1, wherein the housing is formed with an aperture adjacent the cavity or cavities in which the electrical terminals are disposed, such that air can flow through the holder, past the electrical terminals and the electrical component or link.

3) A holder for a lamp bulb as claimed in Claim 1 or Claim 2, wherein at least one slit or opening extends from the socket along at least a portion of the outer wall of the housing, so as to permit airflow into or through said housing.

4) A holder for a lamp bulb as claimed in any preceding claim, wherein the socket comprises a plurality of arms arranged in generally annular configuration, all of the arms being of substantially equal length.

5) A holder for a lamp bulb as claimed in any preceding claim, wherein the housing is of moulded rigid plastics material.

6) A holder for a lamp bulb as claimed in any preceding claim, wherein two of said electrical terminals have spring contact beams which extend into the socket to engage a respective contact of a lamp bulb inserted into the socket.

7) A holder for a lamp bulb as claimed in any preceding claim, wherein the socket is formed in one end of the housing, the opposite end of the housing being provided with slots for receiving power supply leads.

8) A holder for a lamp bulb as claimed in any preceding claim, wherein at least two of said electrical terminals are provided with corresponding power supply lead receiving slots which open towards said opposite end of the housing.

9) A holder for a lamp bulb as claimed in any preceding claim, wherein the slots for receiving the leads of the electrical component or link open towards a side wall of the housing.

10) A holder for a lamp bulb as claimed in any preceding claim, wherein the electrical component comprises a diode.

11) A method of assembling a lamp bulb holder, the method comprising the steps of providing an insulating housing having a socket for receiving a lamp bulb and first, second and third terminal receiving cavities, inserting a first electrical terminal in said first terminal receiving cavity, inserting the leads of an electrical component or link into slots provided in second and third electrical terminals respectively and inserting the assembly comprising the second and third electrical terminals and said component or link into said housing such that said second and third terminals are disposed in said second and third terminal receiving cavities respectively and said electrical component or link is disposed within said housing longitudinally relative thereto.

12) A holder for a lamp bulb, the holder being substantially as herein described with reference to the accompanying drawings.

13) A method of assembling a lamp bulb holder, the method being substantially as herein described with reference to the accompanying drawings.

12) A holder for a lamp bulb, the holder comprising a housing having a main body for receiving a plurality of electrical terminals and a socket for receiving a lamp bulb,

wherein at least one slit or opening extends from the socket along at least a portion of the outer wall of the main body, so as to permit airflow into or through said housing.

13) A holder for lamp bulb, the holder comprising a housing having a main body for receiving a plurality of electrical terminals and a socket for receiving a lamp bulb, the socket comprising a plurality of arms arranged in generally annular configuration, all of said arms being of substantially equal length.

14) A holder for a lamp bulb, the holder being substantially as herein described with reference to the accompanying drawings.

15) A method of assembling a lamp bulb holder, the method being substantially as herein described with reference to the accompanying drawings.

Amendments to the claims have been filed as follows

10) A holder for a lamp bulb as claimed in any preceding

claim, wherein the electrical component comprises a diode.

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