JPH05299694A - Led array light supply - Google Patents

Abstract

PURPOSE:To provide an inexpensive and compact LED array light supply which is free from dispersion in light amount of each LED chip group in an LED array light supply used for an image sensor, etc. CONSTITUTION:An LED chip 12 is formed on a substrate. Specified pieces of LED chips 12 are connected in series and a light amount adjusting resistance 18 is connected in series in common with each LED chip group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED array light source, and more particularly to a cost reduction of an LED array light source used for a light source such as an image sensor and a FAX.

[0002]

2. Description of the Related Art Conventionally, LEs in which LEDs (light emitting diodes) are arranged as light sources for image sensors, fax machines, etc.
D arrays are used.

FIG. 4 shows an example of an LED array light source formed on the substrate 10. Each LED chip 12 is formed of a silicon wafer, and a plurality (3 in FIG. 4) is formed.
Are connected in series with each other. And these 3 LEs
One resistor 14 is assigned to each D chip and is connected in series to the LED chip group connected in series. The lead wire 16 applies a predetermined voltage to each LED chip group to emit light.

FIG. 5 is a circuit diagram of the LED array light source shown in FIG. Three LED chips 12 are connected in series, and the resistors 14 of the LED chip groups connected in series are connected in series. Since each LED chip group is cut out from a different wafer, the forward voltage is different from each other, and therefore, even when the same voltage is applied, the light emission amount may be different. Therefore, a resistor 14 is connected to each LED array chip and the voltage applied to each LED chip group is adjusted by this resistor 14 to set the same amount of light emission.

Incidentally, FIG. 6 shows another example of the conventional LED array light source. In this example, the LED
A plurality of chips are collectively molded, and each LED chip is provided obliquely with respect to the substrate in order to effectively use the substrate.

[0006]

However, in the configuration in which the resistors for adjusting the light amount are connected to each LED chip group as in the above-mentioned conventional technique, the number of resistors increases in proportion to the number of LED chip groups. There is a problem that the substrate area increases and the cost increases. In the LED array light source, the size in the lateral direction (direction in which the LED chip groups are arranged in parallel) is determined by the size of the paper to be read or printed, and thus it is difficult to reduce the size, and thus the substrate area is reduced. In order to achieve this, it is necessary to reduce the size in the vertical direction, and the configuration of arranging resistors in the vertical direction as in the prior art cannot satisfy the demand for the reduction.

The present invention has been made in view of the above problems of the prior art, and an object thereof is an inexpensive and small LE.
It is to provide a D array light source.

[0008]

In order to achieve the above object, the present invention provides an LED array light source in which a plurality of LED chip groups connected in series on a substrate are arranged side by side. It is characterized in that it has a light quantity adjusting resistor commonly connected in series.

[0009]

As described above, in the LED array light source of the present invention, the light quantity adjusting resistor is not connected to each LED chip as in the prior art, but the light quantity adjusting resistor is commonly connected in series to the LED chip group. It is a thing.

As a result, even if the number of LED chips increases, one common resistor may be used, and since only one common resistor is required, it can be installed in the lateral direction of the substrate, and the substrate area can be reduced. It is possible to reduce the cost.

[0011]

The LED according to the present invention will be described below with reference to the drawings.
A preferred embodiment of the array light source will be described.

FIG. 1 shows a plan view of the LED array light source of this embodiment. The LED chips 12 are formed of a silicon wafer and are arranged side by side on the substrate 10. Then, the entire light amount adjusting resistor 18 is formed in the vicinity of the lead wire 16.

Here, a characteristic of this embodiment is that, as shown in the circuit diagram of FIG. 2, a sum number (three in this embodiment) of LED chips are connected in series, and these LED chips are connected in series. This is the point that the light quantity adjusting resistor 18 is connected in series to the common LED chip group. By thus commonly connecting the light quantity adjusting resistors 18 in series, it is possible to adjust the voltage applied to the LED chip groups and adjust the light quantity of each LED chip group to a predetermined amount. When the common resistance is used as described above, the forward voltage Vf of each LED chip needs to be substantially constant, but in view of recent advances in semiconductor technology, LED chips having uniform characteristics are selected, Incorporation into the substrate 10 is easy.

Since the resistors for adjusting the light quantity are shared in this manner, the resistors can be arranged in a small space (near the lead wires) on the substrate 10, and the substrate area (substrate width) can be reduced to reduce the cost. It can be lowered.

In this embodiment, a predetermined number of LEDs are used.
It goes without saying that the chips may be molded together. FIG. 3 shows an example of an LED array light source using such a molded LED chip 20.

[0016]

As described above, the LE according to the present invention
According to the D array light source, it is possible to provide an inexpensive and small-sized LED array light source without variations in the light amount of each LED chip group.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

FIG. 2 is a circuit diagram of the embodiment.

FIG. 3 is a plan view of another embodiment of the present invention.

FIG. 4 is a plan view of a conventional LED array light source.

FIG. 5 is a circuit diagram of a conventional LED array light source.

FIG. 6 is a plan view of another conventional LED array light source.

[Explanation of symbols]

 10 substrate 12 LED chip 16 lead wire 18 light intensity adjustment resistor

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Claims (1)

[Claims] 1. An LED array light source in which a plurality of LED chip groups connected in series on a substrate are juxtaposed, and a light amount adjusting resistor commonly connected in series to the plurality of LED chip groups is provided. LED array light source.