JP3038274B2 - Optical semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device having three kinds of emission wavelengths, and more particularly, to an optical semiconductor device of a three-source color emission type of blue, red and green, in which two or more blue LED chips are connected in series. The present invention relates to an optical semiconductor device that can control three types of LED chips independently without using a high-voltage power supply even when connected.

[0002]

2. Description of the Related Art A conventional optical semiconductor device is shown in FIG.
Description will be made with reference to (1), (2) and (3).

FIG. 3A is a circuit diagram of a conventional optical semiconductor device. In the figure, 101 is a blue LED chip,
Reference numeral 102 denotes a red LED chip, and 103 denotes a green LED chip, each one of which is connected in parallel.

FIG. 3 (3) is a diagram in which a control circuit is added to the circuit of FIG. 3 (1). LED chips 101, 10
2 and 103, respectively, the transistors 111, 1
12, 113 and current limiting resistors 121, 122, 123
Are connected in series, and the gate terminals F, G,
By supplying a control pulse to H, each LED chip 101, 102, 103 is independently controlled.

In general, a blue LED chip 101 is
Since the emission intensity is lower than the red LED chip 102 and the green LED chip 103, as shown in FIG.
By setting the ratio of the blue LED chip 101, the red LED chip 102, and the green LED chip 103 to 2: 1: 1 or the like,
The blue emission intensity is increased.

However, as shown in FIG. 3 (2), when two blue LED chips 101 are connected in series, the terminals A-B, C-B, and D-B can be connected. A high voltage is required only between A and B. In particular, in a blue LED chip using a SiC-based material, the terminal A
It is necessary to apply a voltage of about 7 V to 8 V between -B.

In a 5V system, 12
It is necessary to specially prepare a high-voltage system such as V or to increase the resistance values of the current limiting resistors 122 and 123 connected to the red LED chip 102 and the green LED chip 103 to balance them. , For example, was driven by a 12V system. In this case, the amount of heat generated from the current limiting resistors 121, 122, 123 is large,
Heat dissipation measures were also difficult.

[0008]

As described above, in the conventional optical semiconductor device, when a plurality of blue LED chips are connected in series, a high-voltage power supply system is separately prepared as a separate system. , Other red LED chips and green LE
It is necessary to increase the resistance value of the current limiting resistor connected to the D chip to achieve a balance, and it is necessary to take measures such as driving the entire system with a high-voltage power supply system, and to generate heat from the current limiting resistor. However, there was a drawback that heat dissipation measures were difficult.

The present invention solves the above problems,
Its purpose is to achieve two primary color light emitting type optical semiconductor devices.
When more than one blue LED chip is connected in series,
An object of the present invention is to provide an optical semiconductor device that can control three types of LED chips independently without using a high-voltage power supply.

[0010]

In order to solve the above problems, a first feature of the optical semiconductor device of the present invention is that, as shown in FIG. 1, at least two or more first wavelengths connected in series. At the connection point E between the LED chips 1-1 and 1-2 of the first wavelength and the LED chips 1-1 and 1-2 of the first wavelength, the same polarity as the LED chip 1-1 of the one first wavelength. The second wavelength LED chip 2 and the third wavelength L
The ED chip 3 is provided.

According to a second feature of the present invention, in the optical semiconductor device according to claim 1, the optical semiconductor device includes two LED chips 1-1 and 1-2 having a first wavelength and one LED chip having a first wavelength. Second
LED chip 2 of the third wavelength and one LE of the third wavelength
That is, one unit is constituted by the D chip 3.

According to a third feature of the present invention, claim 1 or 2 is provided.
3. The optical semiconductor device according to claim 1, wherein the first wavelength
The D chips 1-1 and 1-2 are blue light emitting LED chips.

[0013]

In the optical semiconductor device according to the first, second and third aspects of the present invention, as shown in FIG. 1, at least two or more LED chips 1-1 and 1-1 having the first wavelength connected in series. 1
-2 connection point E, one first wavelength LED chip 1
-1, the LED chip 2 of the second wavelength and the LED chip 3 of the third wavelength are connected, and the LED chips 1-1 and 1-2 of the first wavelength and the second wavelength are connected. The control circuits 5, 6, 7, and 8 for controlling the LED chip 2 of the third wavelength and the LED chip 3 of the third wavelength, respectively, are composed of, for example, thyristors 11 and 12 and a current limiting resistor 13, and one of the first Change the phase of the LED chip 1-1 of the wavelength to another LED.
By turning on / off the gates of the thyristors 11 and 12 by inverting the chips, the LED chips 1-1 and 1-2 of the first wavelength and the LE of the second wavelength
The emission intensity of the D chip 2 and the emission intensity of the LED chip 3 of the third wavelength are independently controlled.

Thus, even when two or more blue LED chips are connected in series, the phase control and the timing control of the gate pulse supply can be performed without using a separate high-voltage power supply system. LED chips can be controlled independently, and for example, the display color can be changed in the same manner as the RBG display used in a television or the like.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of an optical semiconductor device according to one embodiment of the present invention.

In FIG. 1A, the optical semiconductor device of this embodiment includes a blue LED chips 1-1 and 1-2, a red LE
D chip 2, green LED chip 3, and control circuit 5,
6, 7, and 8. The connection of LED chip is blue LED chip 1-1, red LED chip 2,
And the green LED chip 3 are connected in parallel, grounded to the ground at the terminal E, and the blue LED chip 1-2 is connected in series.

The control circuits 5, 6, 7 and are connected to terminals A, B, C and D, respectively.
As shown in (2), thyristors 11 and 12 and a current limiting resistor 13 are provided.

As shown in FIG. 2A, only the control circuit 5 connected to the terminal A is supplied with an AC voltage whose phase is shifted by 180 degrees to the terminal F.
By controlling the pulse voltage supplied to the gate terminals of the thyristors 11 and 12 of the seventh and eighth thyristors, the current whose waveform is controlled as shown in FIG.
1 and 1-2, red LED chip 2, and green LED
It is supplied to chip 3.

Therefore, by controlling the pulse voltage supplied to the gate terminals of the thyristors 11 and 12, the blue LED chips 1-1 and 1-2, the red LED chip 2,
In addition, the emission intensity of the green LED chip 3 can be controlled independently, and the display color can be changed in the same manner as in the RBG display used in televisions and the like.

In this embodiment, a sine wave alternating current as shown in FIG. 2A is used. However, the supply current is not limited to this, and a square wave as shown in FIG. It may be. Further, the case where two blue LED chips are used has been described, but a configuration in which three or more blue LED chips are connected in series may be used.

[0022]

As described above, according to the present invention, at least two or more series-connected LED chips of the first wavelength are connected to the same polarity side as one of the first wavelength LED chips. Is short-circuited to connect the LED chip of the second wavelength and the LED chip of the third wavelength, and the control circuit is composed of, for example, a thyristor and a current limiting resistor, and the LE of one of the first wavelengths is connected.
By inverting the phase of the D chip with respect to the other LED chips and performing on / off control of the gate of the thyristor, the first wavelength LED chip and the second wavelength LE chip are controlled.
Since the emission intensity of the D chip and the LED chip of the third wavelength are independently controlled, even when two or more blue LED chips are connected in series, without using another high-voltage power supply system, An optical semiconductor device capable of independently controlling three types of LED chips can be provided.

Further, since the LED chips of the first wavelength are connected in series, it is possible to drive with a lower current source than in the case where the LED chips of the first wavelength are connected in parallel. .

[Brief description of the drawings]

FIG. 1A is a circuit diagram of an optical semiconductor device according to an embodiment of the present invention, and FIG. 1B is a circuit diagram of a control circuit.

FIG. 2 (1) is a voltage waveform diagram of each control circuit of the embodiment, FIG. 2 (2) is a supply current waveform diagram supplied to each LED chip, and FIG. 2 (3) is another control circuit. It is a voltage waveform diagram.

3A is a circuit diagram of a conventional optical semiconductor device, FIG. 3B is a circuit diagram of another conventional optical semiconductor device, and FIG.
(3) is a circuit diagram to which a control circuit is added.

[Explanation of symbols]

1-1, 1-2, 101 LED chip of first wavelength (blue light emitting LED chip) 2,102 LED chip of second wavelength (red light emitting LE
D chip) 3,103 LED chip of third wavelength (green light emitting LE)
D chip) 11, 12 Thyristor 13, 121 to 123 Current limiting resistor 111 to 113 Transistor A, B, C, D, E, F terminal

Claims (3)

(57) [Claims] 1. At least two or more LED chips of a first wavelength connected in series, and an LED chip of the first wavelength
An optical semiconductor, comprising, at a connection point between the chips, an LED chip of a second wavelength and a LED chip of a third wavelength, the one of which is short-circuited on the same pole side as the LED chip of the first wavelength. apparatus. 2. The optical semiconductor device comprises one unit including two LED chips of a first wavelength, one LED chip of a second wavelength, and one LED chip of a third wavelength. The optical semiconductor device according to claim 1, wherein: 3. The optical semiconductor device according to claim 1, wherein the LED chip of the first wavelength is a blue light emitting LED chip.