JP2970359B2 - Lighting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for a combination meter for an automobile, for example, a meter having a plurality of display sections and each of which has a light emitting element for lighting.

[0002]

2. Description of the Related Art Conventionally, a luminaire used for such meters has a light-emitting element such as a lamp or a light-emitting diode for each display unit to be illuminated. For example, illumination by a light emitting element in a combination meter 1 as shown in FIG. 4 is performed.

The combination meter 1 includes a plurality of meters, ie, a speedometer 3, a tachometer 4,
Different display devices such as a fuel gauge 5 and a water temperature gauge 6 are accommodated, and the display plates (translucent dial) are illuminated directly by a light emitting element 7 such as a lamp or a light emitting diode disposed behind or by a light guide, respectively. The speedometer 3 has a light emitting element 7 (3), the tachometer 4 has a light emitting element 7 (4), and the fuel gauge 5 has a light emitting element 7 corresponding to each display device.
(5) The water thermometer 6 is provided with a light emitting element 7 (6).

Conventionally, such a current-carrying circuit configuration for the light-emitting element 7 is such that the light-emitting elements 7 of the respective lighting objects are all connected in parallel to the power supply terminal 8 as shown in FIG. Controls all illumination of the combination meter 1 at the same time.

[0005]

However, a lamp is mainly used as a light-emitting element used for illuminating such a meter, and the number of lamps for a single display portion is reduced due to a thin display device and a light guide illumination structure. As much as possible,
It is desirable to illuminate each illumination object with a single lamp, and this is the number limit required to prevent the high temperature inside the combination meter from being raised by the heat generated by the lamp.

[0006] For this reason, if the only one illumination lamp of one illumination object is disconnected for some reason, it becomes difficult to visually recognize the illumination object until the lamp is replaced. In particular, if this is an item that displays important information, the disconnection is caused. As a result, there arises a problem that an appropriate action based on the information cannot be performed.

In the case where light emitting diodes are used as light emitting elements, the number of light emitting diodes provided for each illumination object needs to be adjusted in order to obtain uniform brightness depending on the size and area of the illumination object. If the number of light-emitting diodes for each lighting object electrically connected in parallel is different, the amount of current must be reduced for a series circuit with a small number of light-emitting diodes in order to make the brightness of the entire meter uniform. Means such as connecting a limiting resistor are taken, but in a series circuit with only a light emitting diode and a series circuit with a resistor interposed,
There is a problem in that the emission luminance of each series circuit varies when the power supply fluctuates.

According to the present invention, it is possible to illuminate an object to be illuminated, which displays particularly important information, with low brightness without completely turning off the light even when some of the illuminating element power supply lines are disconnected. The goal is to keep.

[0009]

According to the present invention, a light emitting element for illumination is provided corresponding to each of a plurality of illumination objects, and each illumination object includes at least two or more light emitting elements. At least one of the light-emitting elements corresponding to the illumination object is electrically connected in series with the light-emitting elements corresponding to other illumination objects, and each light-emitting element of the predetermined illumination object is connected in parallel, Along with the number of light emitting elements of other lighting objects,
The number of light-emitting elements connected in parallel is equal.

[0010]

Even if one of the series circuits of the light emitting elements provided for each illumination object is disconnected, the lighting is maintained without being completely turned off by the other light emitting elements connected in parallel. In addition, by making the number of light emitting elements connected in parallel equal, all the series circuits change with the same characteristics even when the power supply voltage fluctuates, and the brightness of each lighting object as a whole combination meter varies. Lighting with uniform brightness is possible.

[0011]

FIG. 1 shows a circuit configuration of a light emitting device according to an embodiment of the present invention. A light emitting diode is used as the light emitting device. 4 in which three light emitting diodes 12 are connected in series via an illumination switch 11 connected to a power terminal 10
Two series circuits are connected in parallel, and a light emitting diode 12 arranged for each instrument in a combination meter 1 having a speedometer 3, a tachometer 4, a fuel gauge 5 and a water temperature gauge 6 similar to that shown in FIG. Are distributed and connected to separate series circuits.

Each of the speedometer 3 and the tachometer 4 is provided with four light emitting diodes 12, and each of the fuel gauge 5 and the water temperature gauge 6 is provided with two light emitting diodes 12. The three light emitting diodes 12 (3) and the light emitting diode 12 (4) for the tachometer 4 have two of them connected to one series circuit and the other two connected one by one to another series circuit. ing. The light emitting diode 12 (5) for the fuel gauge 5 and the light emitting diode 12 (6) for the water temperature gauge 6 are each connected to a different series circuit.

As described above, by making the connection as shown in FIG. 1, for example, even if one series circuit is disconnected for some reason and the light emitting diode 12 connected to this series circuit does not emit light, Even if the brightness is reduced, the lighting is maintained by the light-emitting diode connected to the normal series circuit, so that the lighting of one lighting object at the time of night lighting etc. suddenly becomes impossible and cannot be visually recognized. Or, the problem of becoming difficult is eliminated.

In particular, the circuit configuration shown in FIG. 1 is one in which the light emitting diodes 12 are distributed and connected to a plurality of series circuits for all four types of illuminated instruments. And information that is particularly important, that is, those that require an emergency response when they become completely invisible, for example, only the speedometer 3 and the fuel gauge 5 have their light emitting diodes 12 (3),
12 (5) can be distributed and connected to a plurality of series circuits, and other instruments can be formed of a single series circuit. By doing so, the wiring pattern associated with the arrangement of the light emitting diodes 12 on the printed board in the combination meter 1 can be simplified.

Further, in the circuit configuration shown in FIG. 1, since the same number of light emitting diodes 12 are connected to all the series circuits, the applied voltage (the amount of current) to each light emitting diode 12 is all the same, and the emission luminance varies. In addition, when the power supply voltage fluctuates, the amounts of current to all the light emitting diodes 12 also change in proportion to the same amount, so that the brightness of the illumination of the four types of instruments only changes in proportion to each other. It will not be different.

The circuit configuration for compensating for the inability of one series circuit to emit light due to the disconnection of the illumination energizing line includes
Three light emitting diodes in each series circuit as shown in FIG.
It is not necessary to connect the same number of 12 light emitting diodes. For example, three light emitting diodes 12 are connected to one series circuit, and two light emitting diodes 12 are connected to one series circuit. The configuration may be such that the diodes 12 are distributed and connected. Depending on the number of light-emitting diodes 12 required for each instrument to be illuminated, the layout in the combination meter 1, or the number of instruments requiring disconnection compensation as described above, Should be selected.

FIG. 2 shows a second embodiment of the present invention, and the connection relationship of light emitting diodes to two types of illumination objects will be described. Assuming that the speedometer 3 and the fuel gauge 5 in FIG. 1 are the objects to be illuminated, as shown in FIG.
The other one is connected to the series circuit of the light emitting diodes 12 (5) for the fuel gauge 5 connected in parallel.

Each series circuit has a current limiting resistor (same resistance value) 13 connected thereto, and each of the series circuits has three light emitting diodes 12 of the same number and one resistor 13 connected to the power supply terminal 10. The connection is made under the same load condition with respect to the voltage through the lighting switch 11. Therefore, even if there is a voltage fluctuation, a fluctuation occurs under the same condition in each series circuit, and the light-emitting conditions of the individual light-emitting diodes 12 are all the same, and the brightness of the illumination changes for each instrument. The defect of the speedometer 3 is eliminated, and the illumination of the speedometer 3 is maintained by the other normal series circuit even if one series circuit is disconnected.

FIG. 3 shows another embodiment for compensating the imbalance of the brightness of the illumination due to the voltage fluctuation.
The four light emitting diodes 12 (3) for the speedometer 3 are distributed and connected as two different series circuits two by two, and the other fuel gauges 5 (3) are connected.
The number of light emitting diodes 12 (5) is connected in parallel with each other, and a current limiting resistor 13 is connected to each series circuit.

Also in this case, the illumination for the speedometer 3 is performed by the light emitting diodes 12 (3) distributed to the two series circuits, so that even if one of the series circuits is disconnected, the illumination is maintained by the other. Since all the series circuits have the same number of circuit configurations including two light emitting diodes 12 and one resistor 13, it is possible to eliminate the illumination imbalance of each instrument due to voltage fluctuation.

[0021]

As described above, according to the lighting apparatus of the present invention, even if a power supply path to a light emitting element for illuminating a plurality of objects to be illuminated is disconnected for some reason and an element that cannot emit light is generated, Lighting is maintained by other light-emitting elements distributed and connected to other power supply circuits connected in parallel, so that even if the brightness is reduced, the lighting is not completely cut off. As for, there is no possibility that the information can not be seen by completely turning off,
There is no need to perform emergency repair, and the reliability can be improved with stable lighting. Also, the light-emitting elements of one illumination object are distributed and connected to a plurality of series circuits, connected in parallel to a power supply together with the series circuits for the other light-emitting elements, and the number of light-emitting elements of each series circuit is set to the same number, and further to each series circuit. By connecting the resistors, it is possible to prevent a problem that the brightness of the lighting for each lighting object changes unbalanced even when the power supply voltage fluctuates, by setting all the series circuits under the same load condition, This provides an excellent effect that the visibility of the entire illumination can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a lighting device according to the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a circuit diagram showing still another embodiment of the present invention.

FIG. 4 is an explanatory diagram of a combination meter to which the lighting device of the present invention is applied.

FIG. 5 is a circuit diagram of a conventional lighting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combination meter 2 Case 3 Speedometer 4 Tachometer 5 Fuel gauge 6 Water temperature gauge 7,12 Light-emitting element 8,10 Power supply terminal 9,11 Lighting switch 12 (3) Light-emitting diode for speedometer 12 (4) Light-emitting diode for speedometer 12 (5) Light emitting diode for fuel gauge 12 (6) Light emitting diode for water temperature gauge 13 Resistance

Claims (4)

(57) [Claims] An illumination light emitting element is provided corresponding to each of a plurality of illumination objects, and the plurality of illumination objects are provided with at least two or more light emitting elements for illumination. A lighting device including a lighting object, wherein at least one of the light emitting elements corresponding to at least one lighting object is electrically connected in series with a light emitting element corresponding to another lighting object. 2. A current-carrying series circuit in which light-emitting elements provided in each of the plurality of illumination objects are connected in series is connected in parallel to a power supply, and the amount of current supplied to each of the current-carrying series circuits is equalized. The lighting device according to claim 1, wherein a series resistor is connected to a predetermined energized series circuit in accordance with the number of connected light emitting elements. 3. A plurality of light-emitting elements for illumination are provided corresponding to each of the plurality of illumination objects, and the plurality of light-emitting elements are distributed and connected by a predetermined number as at least two or more series circuits. A lighting device comprising the series circuit connected in parallel to a power supply having the same number of light emitting elements as other lighting objects. 4. The light-emitting device according to claim 1, wherein the light-emitting elements are light-emitting diodes, and the number of light-emitting diodes of the series circuit connected in parallel is the same in all of the series circuits, and a series resistor is connected to each series circuit. Item 4. The lighting device according to Item 3.