JP3301482B2 - Thyristor and lamp lighting device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lamp lighting device and a thyristor suitable for the same.

[0002]

2. Description of the Related Art In a lighting circuit of a discharge lamp such as a metal halide lamp, a high voltage must be supplied at the start of discharge. For this reason, the lighting circuit has a step-up transformer, and a steep discharge current of the capacitor flows through the primary winding. Conventionally, a gap arrester has been used to discharge the capacitor. However, lighting circuits using gap arresters
Both cost and reliability are not at satisfactory levels.

For this reason, the present applicant has attempted to use a thyristor as the pulse generating element. However, even if a conventional typical thyristor is used, it is impossible to light a metal halide lamp. That is, when the size of the lighting transformer is kept the same as that of the conventional gap arrester, and when the gap arrester is replaced with a thyristor,
Approximately 230 lighting starting voltage required by metal halide lamps
0 V could not be obtained. This is the thyristor d
It is considered that because i / dt, that is, the critical on-current rise rate is small, when the thyristor on the primary winding side is turned on, a very large voltage is not generated in the secondary winding. If the transformer is made large, a large voltage can be obtained in the secondary winding, but this is not practical.

Accordingly, an object of the present invention is to provide a thyristor suitable for lighting a lamp and a lamp lighting device using the thyristor.

[0005]

The present invention for solving the above problems and achieving the above object has a semiconductor substrate, first and second main electrodes, and a gate electrode. A first semiconductor region of one conductivity type, a second semiconductor region of second conductivity type opposite to the first conductivity type, a third semiconductor region of first conductivity type, and a fourth semiconductor of second conductivity type And an area,
The first semiconductor region is disposed so as to be exposed on one main surface of the semiconductor base, and the second semiconductor region is adjacent to the first semiconductor region and is exposed on the other main surface of the semiconductor base. The third semiconductor region is formed in the second semiconductor region in an island shape, and a portion thereof is disposed so as to be exposed on the other main surface of the semiconductor substrate. The semiconductor region of No. 4 is formed in an island shape in the third semiconductor region, and a part thereof is arranged so as to be exposed on the other main surface of the semiconductor base, and the first main electrode is formed of the semiconductor base. The gate electrode is arranged on one main surface of the semiconductor substrate and connected to the first semiconductor region, and the gate electrode is arranged on the other main surface of the semiconductor base and connected to a part of the third semiconductor region. 2 main electrode is provided on the other main surface of the semiconductor substrate. And is connected to a part of the fourth semiconductor region and a part of the third semiconductor region, and a connection part of the third semiconductor region to the second main electrode is connected to the fourth semiconductor region. The shortest distance L2 from the center of the gate electrode to a portion where the second main electrode is connected to the third semiconductor region is the gate electrode. From the center of the fourth
Thyristor is set to be 1.2 to 3.0 times the shortest distance L1 to the semiconductor region.

It is preferable that the second semiconductor region is exposed on one main surface of the base.
It is preferable that the portion of the second semiconductor region exposed on one main surface has a high impurity concentration. Further, it is desirable to configure the lighting device as described in claim 4.

[0007]

According to the present invention, since the distance between the fourth semiconductor region of the thyristor and the gate electrode is longer than in the prior art, the di / dt (critical on-current rise rate) is lower than in the prior art. Therefore, it is possible to provide a thyristor suitable for generating a high voltage when the lamp is turned on. According to the second and third aspects of the present invention, a diode can be built-in. According to the fourth aspect of the invention, since the di / dt of the thyristor is large, a high output voltage can be obtained with a relatively small transformer.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a lamp lighting device and a thyristor according to an embodiment of the present invention will be described with reference to FIGS.

A lamp lighting device according to an embodiment of the present invention shown in FIG. 1 has first and second DC power supply terminals 1a and 1b to which a 400V DC power supply 1 is connected, an output terminal 2, and a ground terminal 3. , A series circuit of a diode 4, a resistor 5, and a capacitor 6, and primary windings N1 and N2 electromagnetically coupled to each other.
It comprises a boost type transformer 7 having a next winding N2, a thyristor 8, and a gate circuit 9.

A metal halide lamp (HID) 10 having a discharge starting voltage of about 2300 V is connected between the output terminal 2 and the ground terminal 3. Secondary winding N2 of transformer 7
Are connected in series between the first DC power supply terminal 1a and the output terminal 2. The ground terminal 3 is connected to the second DC power supply terminal 1b. A series circuit of a diode 4, a resistor 5, and a capacitor 6 includes first and second DC power supply terminals 1.
It is connected between a and b. Thyristor 8 has primary winding N
1 is connected in parallel with the capacitor 6. The gate circuit 9 is a trigger circuit of the thyristor 8, and is connected to the gate electrode 14 of the thyristor 8. The gate circuit 9 supplies a trigger signal to the thyristor 8 when the lamp 10 is turned on.

The thyristor 8 is equivalently a composite element comprising an anti-parallel circuit of a P-gate type thyristor switch S and a diode D. This composite element is called a thyristor in the present application. The first main electrode 12, which can also be called the anode of the thyristor switch S, is connected to one end of the capacitor 6 through the primary winding N1, and the second main electrode 13, which can be called the cathode, is connected to the other end of the capacitor 6. Connected to the end. The anode of the built-in diode D is connected to the second main terminal 13 of the thyristor switch S, and the cathode of the built-in diode D is connected to the second main electrode 12. The polarities of the primary and secondary windings N1 and N2 of the transformer 7 are set as indicated by black circles in FIG.

As shown in FIGS. 2 and 3, the thyristor 8 includes a silicon semiconductor substrate 11, a first main electrode 12,
It comprises a second main electrode 13, a gate electrode 14, an EQR or equipotential ring 15, and an insulating film 16.

The semiconductor substrate 11 is a P-type (first conductivity type) first semiconductor region 1 which can also be called an anode region.
7 and an N-type (second
A second semiconductor region 18 of conductivity type, a third P-type semiconductor region 19 also referred to as a P-type base region, a fourth N-type semiconductor region 20 also referred to as a cathode region, It comprises a well-known P-type field limiting ring region 21 and a well-known N-type channel stopper region 22. The P-type first semiconductor region 17 is the semiconductor substrate 1
The first main surface 23 is formed in a circular shape in a plane so as to be exposed at the center. The N-type second semiconductor region 18 includes a low impurity portion 18a and a high impurity portion 18b. N
The high impurity portion 18 b of the mold is arranged on one main surface 23 of the base 11 so as to surround the first semiconductor region 17. The low-impurity portion 18a is the remaining portion of the second semiconductor region 18 excluding the high-impurity portion 18b, and is disposed between the first and third semiconductor regions 17 and 19 and the other side of the base 11. Are arranged so as to be exposed on the main surface 24. The P-type third semiconductor region 19 is arranged concentrically with the first semiconductor region 17 in plan view, has a circular pattern slightly larger than the first semiconductor region 17, and
It is formed in an island shape in the second semiconductor region 18. N
The fourth semiconductor region 20 of the mold is formed in a ring shape when viewed in plan, and is formed in an island shape in the third semiconductor region 19. P-type field limiting ring area 21
Is formed in a ring shape so as to surround the third semiconductor region 19 via the second semiconductor region 18 in plan view.
The N ⁺ type channel stopper region 22 is disposed so as to surround the fill limiting ring region 21 with the second semiconductor region 18 interposed therebetween.

The first main electrode 12 is formed of a metal layer disposed on one main surface 23 of the base 11, and the first semiconductor region 1
7 and the high impurity portion 18b of the second semiconductor region 18 are electrically connected. The second main electrode 13 is formed of a metal layer disposed on the other main surface 24 of the base 11, and is located between the outer peripheral portion of the fourth semiconductor region 20 and the fourth semiconductor region 20 in the third semiconductor region 19. It is electrically connected to both the outer peripheral portion. The gate electrode 14 is made of a metal layer disposed on the other main surface 24 of the base 11 and is connected to a central circular portion of the third semiconductor region 19. The equipotential ring 15 is a metal layer formed in a ring shape so as to contact the channel stopper region 22. The insulating film 16 is made of a silicon oxide film formed on the other main surface 24 of the base 11, and is arranged so as to separate the second main electrode 13, the gate electrode 14, and the equipotential ring 15 from each other.

In the thyristor 8 shown in FIG. 3, the first, second, third and fourth semiconductor regions 17 at the center of the base 11 are provided.
18, 19, and 20 function as the P-type gate thyristor switch S shown in FIG. The outer peripheral portion of the P-type third semiconductor region 19 and the low impurity concentration portion 18a and the high impurity concentration portion 18b of the N-type second semiconductor region 18 function as the built-in diode D of FIG.

What is important in this thyristor 8 is that
That is, the area of the fourth semiconductor region 20 is significantly reduced as compared with the conventional thyristor. That is, in the conventional thyristor, as shown by a dotted line in the third semiconductor region 18, the inner peripheral side of the fourth semiconductor region 20 extends to the gate electrode 14 side more greatly than in the case of this embodiment. Therefore, the distance L1 'from the center position P0 of the gate electrode 14 to the innermost peripheral position P1' of the conventional fourth semiconductor region 20 indicated by the dotted line and the outermost periphery of the fourth semiconductor region 20 from the central position P0. The ratio L2 / L1 'to the distance L2 from the side position P2 is 5
It was about. Therefore, in the conventional thyristor, the area of the fourth semiconductor region 20 can be made sufficiently large.
The resistance when the thyristor was turned on was reduced, and the power loss was relatively reduced. On the other hand, the thyristor of the present embodiment allows the loss at the time of ON to increase, and instead makes the rise of the current at the time of ON steep and increases di / dt, so that the fourth position from the center position P0 is increased. The ratio L2 / L1 of the shortest distance L1 from the center position P0 to the outermost position P2 of the fourth semiconductor region 20 from the shortest distance L1 to the innermost position P1 of the semiconductor region 20 is 1.2 to 3.0. About 2 in the range
Is set to If L2 / L1 is smaller than 1.2, the area of the fourth semiconductor region 20 becomes too small, and the forward voltage of the thyristor 8 increases. L2 / L
If 1 is larger than 3.0, di / dt required for lighting the lamp 10 cannot be obtained.
The outermost peripheral position P2 of the fourth semiconductor region 20 coincides with the innermost peripheral position of the third semiconductor region 19 where the second main electrode 13 is in contact.

At the time of turning on the thyristor shown in FIG. 2, when a trigger current, that is, a gate signal is applied between the gate electrode 14 and the second main electrode 13, this current is applied to the fourth semiconductor region 2.
Flows below 0. As a result, a voltage drop in the lateral direction of the third semiconductor region 19 occurs, and this voltage drop
Between the first semiconductor region 19 and the fourth semiconductor region 20
When the voltage rises above the forward voltage of the junction, turn-on starts as is well known. Turn on the fourth semiconductor region 2
Starting from the inner peripheral side of 0, it gradually spreads to the outer peripheral side. The spreading speed is relatively slow at about 0.1 mm / μs. In the thyristor of this embodiment, L2 / L1 is set smaller than that of the conventional thyristor, so that the inner peripheral length of the fourth semiconductor region 20, that is, the P-type surrounded by the N-type fourth semiconductor region 20 is used. The length of the outer peripheral edge of the portion of the third semiconductor region 19 increases, the area of the current path of the P-type third semiconductor region 19 increases, the current density can be reduced, and the current can easily flow. That is, di / dt (critical on-current rise rate) is sufficiently larger than that of the conventional thyristor, for example, 2000 A / μs. The di / dt of a conventional thyristor having L2 / L1 'of about 5 is about 300 A / .mu.s.
It is.

FIG. 1 in which the thyristor 8 of FIG. 3 is used.
When the power supply 1 is connected in the lamp lighting device, the capacitor 6 is charged via the diode 4 and the resistor 5, and this voltage becomes substantially the same as the voltage 400V of the power supply 1.
Thereafter, when a trigger signal having a pulse width capable of turning on the thyristor 8 is given from the well-known gate circuit 9 to the gate electrode 14, the thyristor switch S is turned on, and the capacitor 6, the primary winding N1, and the thyristor If a current It flows through the circuit with the switch S and the inductance of the primary winding N1 is L, a voltage based on L.di / dt is generated in the primary winding N1, and the turns ratio is applied to the secondary winding N2. A high voltage corresponding to the above is obtained. Since the secondary winding N2 is connected in series to the power supply 1, a voltage of 2300 V or more, which is the sum of the voltage of the power supply 1 and the voltage of the secondary winding N2, is applied to the lamp 10.
Is applied to Thereby, the lamp 10 is turned on. The lighting maintenance voltage of the lamp 10 is the lighting start voltage (about 2300
V), the discharge or lighting of the lamp 10 is maintained at the voltage of the power supply 1 even after the voltage of the secondary winding N2 generated when the thyristor 8 is turned off disappears. When the thyristor 8 is turned on, as shown in FIG.
A pulse-like current with a large t flows. This current is an oscillating current and flows in the opposite direction. The reverse current of thyristor 8 flows through diode D. This reverse current charges the capacitor 6 in the forward direction. The charging energy of the capacitor 6 can be used at the next lighting. The pulse width of the current when the thyristor 8 is turned on is 1.0 to
Since the current is about 2.0 μs, the power loss in the thyristor 8 is extremely small even if the current flows a plurality of times. Therefore, it is not necessary to consider the power loss of the thyristor 8 so much. In addition,
During the lighting period of the lamp 10, the capacitor 6 is charged by the power supply 1 again, and the preparation for the next lighting is completed. After the lamp 10 is turned on, the current of the thyristor switch S becomes equal to or less than the holding current.

FIG. 4B shows a change in current at the time of ON when a conventional thyristor having a ratio of L2 / L1 'of about 5 is used in the lighting device of FIG. As apparent from FIG. 4B, since di / dt is small, it is impossible to obtain a high voltage on the secondary winding N2, and the lamp 10 does not light.

This embodiment has the following advantages. (1) Increase the turns ratio of the transformer 7 to increase the secondary winding N2
Since it is not necessary to obtain a large voltage, the lamp 10 can be turned on using a small transformer 7,
The size of the lighting device can be reduced. (2) By using the thyristor 8, reliability can be improved and cost can be reduced as compared with the conventional gap arrester.

[0021]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) In the second semiconductor region 18 of the thyristor 8, N
It is desirable to provide the high impurity concentration portion 18b of ⁺ , but if the electrode 12 can be brought into ohmic contact with the low impurity portion 18a, the high impurity portion 18b can be omitted. (2) The built-in diode D can be an externally connected diode. In this case, it is not necessary to connect the second semiconductor region 18 to the first main electrode 12. When a means for absorbing a surge voltage based on the transformer 7 is provided separately, the diode D can be omitted. (3) The conductivity type of each part of the thyristor 8 may be reversed to form an N-type gate thyristor. (4) The thyristor 8 of this embodiment can be used for a discharge lamp or a trigger switch other than a metal halide lamp. In short, the thyristor 8 can be used as a trigger element of various electric circuits.

[Brief description of the drawings]

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

FIG. 2 is a plan view showing a surface of a semiconductor substrate of the thyristor of FIG. 1;

FIG. 3 is an enlarged sectional view showing the thyristor of FIG. 1 along the line AA in FIG. 2;

FIG. 4 is a waveform diagram showing a current change when the thyristor of FIG. 3 and a conventional thyristor are turned on.

[Explanation of symbols]

 Reference Signs List 8 Thyristor 10 Lamp 11 Semiconductor base 12 First main electrode 13 Second main electrode 14 Gate electrode

Claims (4)

(57) [Claims] A first semiconductor region having a first conductivity type; a first semiconductor region having a first conductivity type and a first semiconductor region having a first conductivity type;
A second semiconductor region of a second conductivity type opposite to the conductivity type;
A third semiconductor region of a conductivity type and a fourth semiconductor region of a second conductivity type, wherein the first semiconductor region is disposed so as to be exposed on one main surface of the semiconductor base; The second semiconductor region is disposed so as to be adjacent to the first semiconductor region and exposed on the other main surface of the semiconductor base, and the third semiconductor region is formed in the second semiconductor region in an island shape. The fourth semiconductor region is formed in the third semiconductor region in an island shape, and a part thereof is formed so as to be exposed to the other main surface of the semiconductor substrate. The first main electrode is disposed on the other main surface of the semiconductor substrate, the first main electrode is disposed on one main surface of the semiconductor substrate and connected to the first semiconductor region, and the gate electrode is the semiconductor A third semiconductor disposed on the other main surface of the base and the third semiconductor; The second main electrode is disposed on the other main surface of the semiconductor base, and is connected to a part of the fourth semiconductor region and a part of the third semiconductor region. A connection portion of the third semiconductor region to the second main electrode is disposed on a side opposite to the gate electrode with reference to the fourth semiconductor region; The main electrode is the third
The shortest distance (L
2) The thyristor wherein the distance from the center of the gate electrode to the fourth semiconductor region is set to 1.2 to 3.0 times the shortest distance (L1). 2. The semiconductor device according to claim 1, wherein the second semiconductor region has a portion exposed on one main surface of the semiconductor substrate, and the first main electrode is connected to the exposed portion. Item 3. The thyristor according to Item 1. 3. The semiconductor device according to claim 2, wherein the exposed portion has a higher impurity concentration than a portion between the first and third semiconductor regions of the second semiconductor region. 2. The thyristor according to 2. 4. An apparatus for lighting a lamp, comprising:
First and second DC power supply terminals, a series circuit of a diode, a resistor and a capacitor connected between the first and second DC power supply terminals, and primary and secondary windings electromagnetically coupled to each other; , A thyristor, and a trigger circuit, wherein the primary winding is connected in parallel to the capacitor via the thyristor, and the secondary winding is connected to the first DC power supply terminal and an output. The lamp is connected between the output terminal and the second DC power supply terminal; and the trigger circuit is configured to supply a trigger signal to the thyristor at the start of lamp lighting; The thyristor has a semiconductor substrate, first and second main electrodes, and a gate electrode, and the semiconductor substrate has a first semiconductor region of a first conductivity type and a first semiconductor region.
A second semiconductor region of a second conductivity type opposite to the conductivity type;
A third semiconductor region of a conductivity type and a fourth semiconductor region of a second conductivity type, wherein the first semiconductor region is disposed so as to be exposed on one main surface of the semiconductor base; The second semiconductor region is disposed so as to be adjacent to the first semiconductor region and exposed on the other main surface of the semiconductor base, and the third semiconductor region is formed in the second semiconductor region in an island shape. The fourth semiconductor region is formed in the third semiconductor region in an island shape, and a part thereof is formed so as to be exposed to the other main surface of the semiconductor substrate. The first main electrode is disposed on the other main surface of the semiconductor substrate, the first main electrode is disposed on one main surface of the semiconductor substrate and connected to the first semiconductor region, and the gate electrode is the semiconductor A third semiconductor disposed on the other main surface of the base and the third semiconductor; The second main electrode is disposed on the other main surface of the semiconductor base, and is connected to a part of the fourth semiconductor region and a part of the third semiconductor region. A connection portion of the third semiconductor region to the second main electrode is disposed on a side opposite to the gate electrode with reference to the fourth semiconductor region; The main electrode is the third
The shortest distance (L
2) The lamp lighting device, wherein the distance from the center of the gate electrode to the fourth semiconductor region is set to 1.2 to 3.0 times the shortest distance (L1).