LED illuminator

Each of a plurality of LED lamp modules includes a base, an LED drive circuitry mounted on the base, and a cover coupled with the base to cover the LED drive circuitry. The LED lamp modules are stacked one on another. A single flat cable is extending through the LED lamp modules so as to have at least one first portion disposed outside the LED lamp modules and a plurality of second portions disposed inside the LED lamp modules to be electrically connected to the LED drive circuitry in each of the LED lamp modules. The first portion of the flat cable is sandwiched between the base of an upper one of the LED lamp modules and the cover of a lower one of the LED lamp modules.

BACKGROUND OF THE INVENTION

The present invention relates to a small-sized illuminator provided with an LED (light-emitting diode) which is used as a room light or a map light of a vehicle to illuminate the cabin and the interior of a container for small items such as a console box, a glove compartment, an accessory pocket, or an ash tray. It may also illuminate a cup holder or the area of passengers' feet.

FIG. 6shows a first example of a related-art illuminator which is disclosed in Japanese Patent Publication No. 9-272377 (cf., pages 2–4, FIG. 1).

In this example, an illuminator60is capable of illuminating the interior of containers for small items such as a console box66with adequate luminance at low power consumption. The illuminator comprises a main body61, a circuit board63attached to the main body61, and a lens65which covers the circuit board63.

The main body61is formed in a box-shaped general configuration using a synthetic resin material. A mount62for mounting the illuminator60to a surface of a wall of the console box66is provided in a lower part of the main body61. Each of the circuit board63and the lens65is securely held on the main body61using an engagement member.

A plurality of LED chips64are mounted on the circuit board63. The LED chips64are arrayed and connected to an alternator and a battery through branch lines66so that the emitted light linearly. The circuit board63is also provided with electronic components such as a rectifier diode for preventing noises and a current limiting resistor which are not shown.

The lens65is formed in a box-shaped configuration from a highly transparent synthetic resin material. Therefore, light emitted from the LED chips64is converged as it passes through the lens65to illuminate the interior of the console box66with high luminance.

With such a configuration, since a large number of LED chips64are mounted, an illuminator can be provided which can illuminate the interior of a container for small items with sufficient luminance and which consumes small power.

In this example, since ends of the two branch lines66are connected to the circuit board53, a new branch line66must be formed on the trunk line to provide an additional illuminator. This is troublesome and costly, and a problem arises in that an additional illuminator cannot be easily provided.

Further, since the plurality of LED chips64is mounted on the circuit board63, a problem arises in that the main body61is therefore large-sized and cannot be mounted to a container for small items which has only a small space therein. For example, the lamp may not be mounted to an ash tray or cup holder. When the intervals between the plurality of LED chips64are decreased to reduce the size of the illuminator60, a problem arises in that the temperature in the illuminator60increases because of poor heat radiation to reduce light-emitting efficiency. In particular, a red LED chip may undergo an abrupt reduction of light-emitting efficiency at a high temperature.

When the illuminator60is used in a container for small items such as an ash tray or cup holder, it will sufficiently work with a small number of LED chips64because high luminance is not required. When the illuminator60is used in a console box or a glove compartment or used as a map light, it must have a large number of LED chips64because high luminance is required. While the number of the LED chips64depends on the size of the container for small items or the place to be illuminated, the illuminator60cannot accommodate an increase or decrease in the number of the LED chips64with flexibility. It is therefore required to redesign the main body61, the circuit board63, and the lens65to satisfy such a requirement, which results in the problem of an increase in total cost including tooling costs.

FIG. 7shows a second example of an related-art illuminator. In this example, illuminators70which are mounted in containers for small items such as a console box and glove compartment in a way similar to that in the first example. The illuminators70are connected to a wire harness75provided in a vehicle through joint connectors71, branch lines72, and module-side connectors73in a manner so-called bus-type connection.

When an additional illuminator70is to be provided, a new joint connector71, branch line72, and module-side connector73are prepared and are arranged along the wire harness75similarly to the other illuminators70in parallel with them.

In this example, although it is advantageous in that connecting operations are simple because the illuminators70are connected to ends of the branch lines72using connectors, there is a problem in that the illuminators cannot be made small. Further, since the illuminators70are connected to the wire harness75through the joint connectors71, the branch lines72, and the module-side connectors73, there is a problem in that a large number of components are involved to result in a high total cost. Further, since the illuminators70are connected to ends of the branch lines, not intermediate portions of the same in a manner similar to that in the first example, there is a problem in that it is uneasy and troublesome to provide an additional illuminator70.

FIG. 8shows a third example of an related-art illuminator. The present example is different from the second example in that a plurality of illuminators80is serially connected to a branch line81which branches from a wire harness.

Each of the illuminators80is constituted by a case87formed by a base84and a cover86and a connecting circuit. Both of the base84and the cover86are provided by molding a synthetic resin material having insulating properties. An intermediate section of the branch line81is soldered to the connecting circuit.

In this example, a redundant part81aof the cable81is left between the adjoining illuminators80to facilitate the assembly of each of the illuminators80. However, if the redundant part81ais too long, the cable can be flapped by vibration of the vehicle when it is running, which results in the problem of the generation of noises and damage of the cable due to interference with its surroundings.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide an illuminator provided with LED chips (hereinafter, simply referred as an LED illuminator) capable of solving the above problems, particularly to prevent a redundant part of an cable from flapping to thereby eliminating the generation of noises and the damaged due to interference with its surroundings.

In order to achieve the above object, according to the invention, there is provided an LED illuminator, comprising:

a plurality of LED lamp modules, each of which comprises:a base;an LED drive circuitry, mounted on the base; anda cover, coupled with the base to cover the LED drive circuitry, the LED lamp modules being stacked one on another; and

a flat cable, extending through the LED lamp modules so as to have at least one first portion disposed outside the LED lamp modules and a plurality of second portions disposed inside the LED lamp modules to be electrically connected to the LED drive circuitry in each of the LED lamp modules,

wherein the first portion of the flat cable is sandwiched between the base of an upper one of the LED lamp modules and the cover of a lower one of the LED lamp modules.

With such a configuration, since the plurality of the LED lamp modules connected to the flat cable are stacked one on another, the luminance of the LED lamps can be adequately adjusted depending on the specifications of areas to be illuminated. Since the redundant part (the first portion) of the flat cable is sandwiched between the base of the upper module and the cover of the lower modules, the generation of noises and damage due to flapping of the redundant part of the flat cable can be prevented.

Preferably, an outer face of the base is formed with a groove for receiving the first portion of the flat cable.

With such a configuration, the redundant part of the cable is securely positioned by being contained in the groove, which prevents a transverse shift of the redundant part. Therefore, the first portion is completely protected from interference with its surroundings.

Preferably, the cover comprises a retainer which retains each of the second portions of the flat cable on an inner face of the base.

With such a configuration, the flat cable can be prevented from being lifted from the inner face of the base even when the first portion of the flat cable is folded back to be sandwiched by the LED lamp modules.

Preferably, each of the LED lamp modules comprises a guide member disposed on an inner face of the base to restrict a lateral movement of each of the second portions of the flat cable.

With such a configuration, the flat cable extended along the inner and outer faces of the base can be prevented from being damaged due to the friction caused by the lateral movement.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the invention will be described below in detail with reference to the accompanying drawings.

An LED illuminator10is a small-sized illuminator which is provided by stacking LED lamp modules34serially connected to a two-core flat cable40and which is used as a room light or a map light of a vehicle for illuminating the cabin and the interior of a container for small items such as a console box, a glove compartment, or an accessory pocket.

The plurality of LED lamp modules34is disposed at predetermined intervals before they are stacked one on another such that a redundant part41of the flat cable40is left as seen in the related-art example shown inFIG. 8. The flat cable40is a single cable which extends through the plurality of LED lamp modules34. The number of the LED lamp modules34connected to the flat cable40may be more than two.

The LED illuminator10is operated by power supplied from a battery through the flat cable40. A junction box and a joint connector which are not shown are connected to an upstream side of the flat cable40. For example, the junction box is connected to a battery through a wire harness which is not shown, and the joint connector is connected to the junction box through the wire harness. The LED lamp modules34are connected to the joint connector through the single flat cable40. When the junction box has the function of branching the wire harness which is a trunk line, the flat cable40can be branched from the junction box without providing the joint connector.

The junction box is a well-known electric connection box made of a synthetic resin containing a circuit board and a wiring board and also having electrical components such as connectors, relays, and fuses connected to the wiring board. For example, the junction box is provided in the engine room of a vehicle or in the neighborhood of an instrument panel thereof. The joint connector is provided downstream of the junction box, e.g., at a front pillar or in the neighborhood of the same.

Each of the LED lamp modules34is comprised of a base12, a bus bar circuit35provided with an LED chip38, and a cover25. A box-shaped case is formed by the base12and the cover25.

The rectangular plate-shaped base12is formed by molding a synthetic resin material having insulating properties. As shown inFIGS. 2and5, the base12is formed with an groove23, engagement claws16, reinforcement ribs20, and guide members22which are described later in detail. The material of the base12is not limited to a synthetic resin, and it may be formed of any other material such as hard silicone rubber or ceramics as long as it has high insulating properties and moldability.

The flat cable40is constituted by one positive-side cable (power supply line) with insulation coating and one negative-side cable (ground line) with insulation coating which are connected in parallel with each other by a flat insulation band provided therebetween, but two cables are separatable at a desired portion (seeFIG. 5). The flat cable40extends through the LED lamp modules34without any discontinuation while a part of the flat cable40is electrically connected to each bus bar circuit35.

The bus bar circuit35has a thin plate-shaped bus bar36which is formed by punching a conductive substrate according to a circuit pattern. An LED chip38and a constant-current diode39are soldered to the bus bar36.

As shown inFIG. 5, the conductive bus bar36is formed with pairs of terminals37and engagement pieces45. The terminals37extend upright from an end of the bus bar36so that each electric wire of the flat cable40is press-fitted into each pair of the terminals37to establish the electric contact between the power supply and the flat cable40. Since the terminals37are connected to the constant-current diode39and the LED chip38through the bus bar36, the power supply current is supplied to the LED chip38through the constant-current diode39.

The engagement pieces45are provided in some locations of the bus bar36as needed. Those engagement pieces45are inserted into recesses21formed on the base12to secure the bus bar36on the base12in a single action.

The W-shaped guide members22are members for keeping the flat cable40wired on the inner face13aof the base12straight while restricting the lateral movement thereof. Specifically, the positive-side cable40ais held between one of the outer walls22aand a center wall22b, while the negative-side cable40bis held between the other one of the outer walls22aand the center wall22b. An interval between each outer wall22aand the center wall22bis made smaller than an outer diameter of each of the cables40a,40bto securely hold the cables40a,40bon the guide member22.

The reinforcement ribs20extend upright from the inner face13aof the base and disposed between the guide members22for reinforcing the terminals37. Each pair of the reinforcement ribs20is associated with one pair of the terminals37. Each pair of the terminals37is disposed between one pair of the reinforcement ribs20and one guide member22as shown inFIGS. 3 and 5. With this configuration, the terminals37are prevented from being inclined by the reinforcement ribs20and the guide members22when the press-fitting of the cables40a,40bis performed.

The LED chip38is a white light-emitting diode of surface-mount type having two terminals, i.e., positive and negative terminals on the bottom surface thereof. The LED chip38used in the present embodiment has a rated current of 20 mA and a rated voltage of 3.5V. The battery voltage is decreased by the constant-current diode39and adjusted to the rated voltage of 3.5V. While the constant-current diode39is advantageous in a case where a voltage fluctuates as can be observed in a vehicle, a current-limiting resistor may alternatively be used when there is no voltage fluctuation. The color of the LED chip38is not limited to white, and it may be red, blue or green.

The LED chip38is characterized in that it consumes small power and has a long life, high directivity, and high luminance. It consumes small power and has a long life because it converts electricity into light with very high efficiency (90%). It has high directivity and high luminance because it emits no diffuse light unlike an incandescent lamp. The invention is not limited to an LED chip38as described above, and LED chips having various outputs may be used. Further, the invention is not limited to a surface mount type LED chip38, and a bullet-shaped LED chip may be used.

As shown inFIG. 5, the box-shaped cover25is formed by molding a resin so as to comprise a ceiling wall26and circumferential walls30which is orthogonal to and contiguous with the edges of the ceiling wall26. A space is defined by the ceiling wall26and circumferential walls30so as to be adapted to cover and protect the bus bar circuit35. The circumferential walls30are formed with retaining grooves33, an window31, an inlet42and an outlet44for the flat cable40. The ceiling wall26is formed with retainers43.

The engagement claws16extend upright from the inner surface13aof the base12in positions associated with the retaining grooves33formed on the cover25. As shown inFIG. 3, a claw member16ais formed on a distal end of each engagement claw16so that the engagement claws16and the retaining grooves33are engaged to combine the base12and the cover25such that they will not accidentally come apart as shown inFIG. 2.

The rectangular window31releases the light emitted from the LED chip38to the outside. The edges of the window31are chamfered into slope faces31aso that the released light is allowed to be diffused at a predetermined angle (120 degrees in this embodiment). A reflective material may be applied to a ceiling surface31of the light projecting window31, the surface of the ceiling wall26facing a top face of the LED chip38that constitutes a light-emitting surface38athereof. Thus, light emitted from the light-emitting surface38ais reflected by the reflective material and emitted out of the window31with high efficiency.

As shown inFIG. 2, the outlet42and the inlet44are recesses communicating the inside and the outside of the circumferential walls30, so that the flat cable is allowed to pass therethrough to be led into or out of the module34.

In this embodiment, as shown inFIG. 1, two LED lamp modules34connected to the flat cable40are stacked one on another to constitute the LED illuminator10. Incidentally, as shown inFIGS. 1 and 4, the flat cable40extends while being sandwiched by the base12of the upper module and the cover25of the lower module. More specifically, the flat cable40wired along an inner face13aof the base12of the upper module34is led out from an outlet42(seeFIGS. 1 and 2) and folded back such that the redundant part41extends along an outer face13bof the base12. The flat cable40is again folded back to be led into the lower module34through an inlet44. That is, as shown inFIG. 4, the flat cable40is wired like a crank.

With such a configuration, since the redundant part41located between the adjoining LED lamp modules34is sandwiched between the base12and the cover25of the LED lamp modules34stacked one on another, the redundant part41will not be exposed to the outside, which prevents the generation of noises and damage due to the flapping of the redundant part.

As shown inFIGS. 1 through 3, the groove23is formed on the outer surface13bof the base12so as to contain the redundant part41of the flat cable40. The groove23is formed with a depth equal to or greater than the thickness of the flat cable40so that the redundant cable can be completely contained. The groove23is formed with a width similar to the width of the flat cable40so as to restrict the lateral movement of the redundant part41.

Thus, the redundant part41of the flat cable40will not be exposed on the outside of the LED lamp module34, which completely prevents damage on the cable due to interference with the surroundings.

The retainers43extend from the ceiling wall26so as to oppose to the outlet42and the inlet44, respectively. When the base12and the cover25are combined, the tip ends of the retainers43press the flat cable40to prevent the flat cable40from moving in the longitudinal direction thereof. Further, the retainers43prevent the flat cable40from being lifted from the inner face13aof the base12even when the flat cable40led out from the outlet42is folded back to be accommodated in the groove23as described the above.

As thus described, according to the present embodiment, the bus bar circuit35mounted on the base12is covered by the cover25to protect electrical components such as the LED chip38and the constant-current diode39and to thereby maintain reliability of electrical connections. Since the plurality of LED lamp modules34connected to the flat cable40are stacked one on another, the luminance of the LED lamps can be adjusted according to the specifications of an area to be illuminated. Since the redundant part41of the flat cable40is left between the adjoining LED lamp modules34, the assembling workability of the LED lamp modules34is improved. Since the redundant part41of the flat cable40is sandwiched between the base12of the upper module34and the cover25of the lower module34, the generation of noises and damage due to flapping of the cable can be avoided.