JP2011023397A - Light source device, and method of controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set proper driving currents for semiconductor light sources in accordance with differences in their luminous intensity ranks. <P>SOLUTION: This light source device 100 includes a semiconductor light source 10a; a first Zener diode 11a having a first breakdown voltage, with a cathode connected to an anode of the semiconductor light source; a second Zener diode 12a having a breakdown voltage lower than that of the first breakdown voltage, with an anode connected to an anode of the first Zener diode, and a cathode connected to a cathode of the semiconductor light source; voltage impressing parts 21, 22, 23, 24 to impress a reverse voltage to the semiconductor light source; voltage detecting parts 21, 23 to detect a voltage generated between the anode and cathode of the semiconductor light source when the reverse voltage is impressed on the semiconductor light source; and a current setting part 21 to set the magnitude of a current to be supplied to the semiconductor light source, based on the voltage detected by the voltage detecting parts. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an operation control technique for a light source device including a semiconductor light source.

  As a semiconductor light source drive circuit, for example, one disclosed in Japanese Patent Application Publication No. 2007-200670 is known (Patent Document 1). The drive circuit disclosed in Patent Document 1 includes a plurality of semiconductor light sources connected in series to each other, a switching regulator that supplies power from each power source to each semiconductor light source, and a semiconductor light source and a protection circuit in the event of a circuit failure. It is configured. In such a drive circuit, the switching regulator is configured to flow a constant current to the semiconductor light source. Moreover, since the semiconductor light sources are connected in series, the same current flows through all the semiconductor light sources. The protection circuit has a function of detecting a disconnection or a short circuit of the semiconductor light source, stopping the switching regulator, and sending an abnormality detection signal to the outside.

  When a semiconductor light source is used, it is necessary to design in consideration of the forward voltage Vf and the luminous intensity (brightness) rank of each semiconductor light source. Here, the forward voltage Vf means a voltage between the anode and the cathode of the semiconductor light source generated when a constant forward current If flows. When the same forward current If is passed through the same semiconductor light source, individual brightness may differ due to individual differences. For this reason, semiconductor light sources are ranked according to their brightness.

  By the way, in a final product configured using a semiconductor light source (for example, an in-vehicle lamp), it is not desirable that nonuniform brightness occurs due to a difference in luminous intensity rank of the semiconductor light source. As a countermeasure for this, for example, it is conceivable to select and use only a semiconductor light source having a high luminous intensity rank. However, this countermeasure has a disadvantage that a semiconductor light source having a low luminous intensity rank cannot be used effectively. On the other hand, in order to effectively use a semiconductor light source with a low luminous intensity rank, a measure to cope with by combining a driving circuit capable of supplying an appropriate current according to the luminous intensity rank in advance by selecting the luminous intensity rank of the semiconductor light source. Is also possible. However, in this case, since it is necessary to prepare a plurality of types of drive circuits corresponding to each luminous intensity rank, there arises a problem that inventory increases and costs increase.

JP 2007-200670 A

  A specific aspect of the present invention is to provide a technique capable of setting and supplying an appropriate driving current corresponding to a difference in luminous intensity rank to a semiconductor light source.

  A light source device according to one aspect of the present invention includes: (a) a semiconductor light source; (b) a first Zener diode having a first breakdown voltage and having a cathode connected to the anode of the semiconductor light source; A second Zener diode having a second breakdown voltage less than the first breakdown voltage, an anode connected to the anode of the first Zener diode, and a cathode connected to the cathode of the semiconductor light source; (D) a voltage application unit that applies a reverse voltage to the semiconductor light source; and (e) a voltage detection that detects a voltage generated between the anode and the cathode of the semiconductor light source when the reverse voltage is applied to the semiconductor light source. And (f) a current setting unit that sets a magnitude of a current to be supplied to the semiconductor light source based on the voltage detected by the voltage detection unit.

  According to the light source device described above, the luminous intensity rank of each semiconductor light source is detected based on the voltage between terminals when a reverse voltage is applied, and a drive current having an appropriate magnitude to be supplied to the semiconductor light source according to the detection result Can be set autonomously. Therefore, it is not necessary to prepare a plurality of drive units (drive circuits) corresponding to the luminous intensity rank, and the problem of inventory and cost is solved.

  The light source device may further include a power control unit (regulator or the like) that controls power supplied to the semiconductor light source. In this case, the current setting unit sets the magnitude of the current by giving a predetermined control signal to the power control unit.

  As a result, the driving current supplied to the semiconductor light source can be controlled inside the light source device based on the power supplied from the power supply or the like without giving a load such as a design change to the power supply unit such as an external power supply. In addition, you may comprise so that an external power supply etc. may be directly controlled by an electric current setting part.

  In the light source device, the power control unit preferably starts supplying power to the semiconductor light source after the magnitude of the current is set by the current setting unit.

  Thereby, the semiconductor light source is turned on after the magnitude of the current is appropriately set, which is more convenient from the viewpoint of protecting the semiconductor light source (avoiding damage).

  A method of controlling a light source device according to an aspect of the present invention includes: (a) a semiconductor light source; (b) a first Zener diode having a first breakdown voltage and having a cathode connected to the anode of the semiconductor light source; (C) a second Zener having a second breakdown voltage lower than the first breakdown voltage, an anode connected to the anode of the first Zener diode, and a cathode connected to the cathode of the semiconductor light source A method of controlling a light source device comprising: a diode; (d) a first step of applying a reverse voltage to the semiconductor light source; and (e) a semiconductor light source when the reverse voltage is applied to the semiconductor light source. A second step of detecting a voltage generated between the anode and the cathode of the semiconductor, and (f) a magnitude of a current to be supplied to the semiconductor light source based on the voltage detected in the second step Including a third step of setting.

  According to the above control method, the luminous intensity rank of each semiconductor light source is detected based on the voltage between terminals when a reverse voltage is applied, and a drive current of an appropriate magnitude to be supplied to the semiconductor light source according to the detection result Can be set. Therefore, it is not necessary to prepare a plurality of drive units (drive circuits) corresponding to the luminous intensity rank, and the problem of inventory and cost is solved.

It is a circuit diagram which shows the structure of the light source circuit of one Embodiment. It is a figure which shows the structure of the light source device of one Embodiment. It is a figure which shows the structure of the light source device of other embodiment. It is a figure for demonstrating the deformation | transformation Example of a light source device. It is a figure for demonstrating the deformation | transformation Example of a light source device.

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

  FIG. 1 is a circuit diagram illustrating a configuration of a light source circuit according to an embodiment. The light source circuit of this embodiment includes a semiconductor light source (including a multichip) 10, a first Zener diode 11, and a second Zener diode 12. The first Zener diode 11 and the second Zener diode 12 are connected in series with their anodes connected to each other. The entirety of the first Zener diode 11 and the second Zener diode 12 is connected in parallel with the semiconductor light source 10.

  Specifically, the cathode terminal of the first Zener diode 11 is connected to the anode terminal of the semiconductor light source 10, and the cathode terminal of the second Zener diode 12 is connected to the cathode terminal of the semiconductor light source 10. The first Zener diode 11 is for preventing damage of the semiconductor light source 10 due to static electricity, and has a Zener voltage (breakdown voltage; for example, about 20 to 30 V) higher than the forward voltage Vf of the semiconductor light source 10. The second Zener diode 12 is for identifying the luminous intensity rank of the semiconductor light source 10, and has a relatively low Zener voltage (for example, about 3 to 5V).

  The operation of the light source circuit shown in FIG. 1 will be described below. In normal use, a positive potential may be applied to the anode side of the semiconductor light source 10 and a negative potential may be applied to the cathode side. Thereby, the semiconductor light source 10 can be turned on.

  The operation of each Zener diode at this time is as follows. Since the first Zener diode 11 for preventing static electricity has a Zener voltage having a value higher than the forward voltage Vf of the semiconductor light source 10, it does not conduct. Further, the second Zener diode 12 for identifying the light intensity rank is not conducted. That is, when the semiconductor light source 10 is normally lit, the Zener diodes 11 and 12 do not conduct.

  Next, consider a case where a high voltage caused by static electricity or the like is applied to the anode terminal side of the semiconductor light source 10. In this case, the first Zener diode 11 becomes conductive. The second Zener diode 12 is also turned on by generating the forward voltage Vf. That is, static electricity is clamped by a voltage corresponding to the sum of “the Zener voltage of the first Zener diode 11” and “the forward voltage Vf of the second Zener diode”, and the semiconductor light source 10 is protected.

  Next, consider a case where a negative potential is applied to the anode side of the semiconductor light source 10 and a positive potential is applied to the cathode side of the semiconductor light source 10 contrary to the normal lighting. In this case, since the reverse voltage is applied to the semiconductor light source 10, the semiconductor light source 10 is not turned on (not lighted). At this time, the second Zener diode 12 for identifying the luminous intensity rank conducts and has a selected voltage. Further, the first Zener diode 11 for electrostatic protection has a forward voltage Vf and becomes conductive. That is, if a Zener potential corresponding to the luminous intensity rank is set as the forward voltage of the second Zener diode 12 for identifying the luminous intensity rank, the semiconductor light source 10 can be obtained by applying a reverse voltage to the semiconductor light source 10. The light intensity rank of will be understood. This will be specifically described below.

  As an example, it is assumed that the light intensity rank of the semiconductor light source 10 includes three ranks of 1 (bright) to 3 (dark). If luminosity rank 1 is 3.9V (variation range 3.74 to 4.16V), luminosity rank 2 is 4.7V (variation range 4.42 to 4.9V), and luminosity rank 3 is 5.6V (variation range 5.31 to 5.92V) If a reverse voltage is applied to the light source 10 and a voltage generated at both ends of the semiconductor light source 10 is detected at that time, the luminous intensity rank of the semiconductor light source 10 can be identified.

  In the light source circuit shown in FIG. 1, even if a high voltage due to static electricity or the like is applied to the semiconductor light source 10 in the reverse direction, the semiconductor light source 10 is protected in the same manner as described above. That is, static electricity is clamped by a voltage corresponding to the sum of “the forward voltage Vf of the second Zener diode” and “the Zener voltage of the first Zener diode 11”, and the semiconductor light source 10 is protected.

  Next, a configuration example of a light source device including the above-described light source circuit and having a function of setting an appropriate drive current value according to the luminous intensity rank of the semiconductor light source 10 will be described.

  FIG. 2 is a diagram illustrating a configuration of a light source device according to an embodiment. The light source device 100 shown in FIG. 2 can autonomously set an appropriate driving current value according to the luminous intensity rank of each semiconductor light source. The light source device 100 is used as, for example, a vehicular lamp, and is a light source unit 1, a circuit unit 2, and wiring for electrically connecting the light source unit 1 and the circuit unit 2. And a harness 3.

  The light source unit 1 is configured by directly connecting the light source circuits shown in FIG. 1 described above in three stages. Specifically, the light source unit 1 includes three semiconductor light sources 10a, 10b, and 10c, three first Zener diodes 11a, 11b, and 11c, and three second Zener diodes 12a, 12b, and 12c. It consists of The first Zener diode 11a and the second Zener diode 12a are connected in parallel to the semiconductor light source 10a, the first Zener diode 11b and the second Zener diode 12b are connected in parallel to the semiconductor light source 10b, and the first Zener A diode 11c and a second Zener diode 12c are connected in parallel to the semiconductor light source 10c.

  The circuit unit 2 is controlled by the switching regulator 20 that constitutes a constant current circuit when power is supplied from the outside, the microcomputer 21 that manages the timing of detecting the luminous intensity rank and the driving timing of the switching regulator 20, and the microcomputer 21. An FET (transistor) 22 for short-circuiting or opening the anode side of the semiconductor light source 10a, a switch unit 23 that is also controlled by the microcomputer 21 and short-circuited when detecting the light intensity rank, and the microcomputer 21 and the switch unit 23 And a resistance element 24 connected to the.

  Although details will be described later, in the present embodiment, the microcomputer 21, the FET 22, the switch unit 23, and the resistance element 24 correspond to a “voltage application unit”, and the microcomputer 21 and the switch unit 23 correspond to a “voltage detection unit”. The microcomputer 21 corresponds to a “current setting unit”. The switching regulator 20 corresponds to a “power control unit”.

  The light source device 100 of this embodiment has such a configuration, and the operation thereof will be described next. First, when power is supplied to the switching regulator 20, the microcomputer 21 stops the operation of the switching regulator 20. Next, the microcomputer 21 supplies a control signal for turning on the FET 22 to the FET 22 and supplies a control signal for turning on the switch unit 23 to the switch unit 23. Thereby, the anode side of the semiconductor light source 10a is connected to the reference potential (ground potential), and a voltage is applied to the cathode side from the power source V1 via the resistance element 24. That is, a reverse voltage is applied to the semiconductor light source 10a. At this time, a Zener voltage corresponding to the luminous intensity rank is generated between the terminals of the semiconductor device 10a.

  The microcomputer 21 detects a Zener voltage generated between the terminals of the semiconductor device 10a. Specifically, the microcomputer 21 takes in a Zener voltage as a digital signal via a built-in analog / digital converter (not shown). Then, the microcomputer 21 sets the constant current output value of the switching regulator 20 based on the acquired Zener voltage. Next, the microcomputer 21 turns off the FET 22 and the switch unit 23 by supplying predetermined control signals to the FET 22 and the switch unit 23, respectively. Then, the microcomputer 21 outputs a control signal that gives an operation permission to the switching regulator 20. Thereby, the switching regulator 20 starts an operation of supplying a drive current to the light source unit 2. Specifically, the switching regulator 20 increases or decreases the output voltage so as to obtain a set current value, and turns on the semiconductor light sources 10a to 10c.

  In the present embodiment, it is assumed that the semiconductor light sources 10a to 10c have the same luminous intensity rank. For this reason, an appropriate drive current value can be set for each of the semiconductor light sources 10a to 10c only by detecting the luminous intensity rank for any one of the semiconductor light sources (in this example, the semiconductor light source 10a).

  FIG. 3 is a diagram illustrating a configuration of a light source device according to another embodiment. The light source device 100a shown in FIG. 3 basically has the same configuration as the light source device 100 shown in FIG. 2 described above, and automatically sets an appropriate drive current value according to the luminous intensity rank of each semiconductor light source. Is possible.

  Compared to the light source device 100 shown in FIG. 2, the light source device 100 a shown in FIG. 3 has a reference potential (ground potential) in the middle of the wiring connecting the switching regulator 20 of the circuit unit 2 a and the semiconductor light source 10 of the light source unit 1. The direct connection is different in configuration. That is, the FET 22 in the light source device 100 shown in FIG. 2 is omitted in the light source device 100a shown in FIG. The light source device 100a is configured such that the anode side of the semiconductor light source 10a is set to a reference potential and the cathode side of the semiconductor light source 10c is set to a negative voltage.

  The light source device 100a of this embodiment has such a configuration, and the operation thereof will be described next. First, when power is supplied to the switching regulator 20, the microcomputer 21 stops the operation of the switching regulator 20. Next, the microcomputer 21 supplies a control signal for turning on the switch unit 23 to the switch unit. As a result, the anode side of the semiconductor light source 10a is connected to the reference potential (ground potential), and a voltage is applied to the cathode side from the power source V2 via the resistance element 24. That is, a reverse voltage is applied to the semiconductor light source 10a. At this time, a Zener voltage corresponding to the luminous intensity rank is generated.

  The microcomputer 21 detects a Zener voltage generated between the terminals of the semiconductor device 10a. Specifically, the microcomputer 21 takes in a Zener voltage as a digital signal via a built-in analog / digital converter. Then, the microcomputer 21 sets the constant current output value of the switching regulator 20 based on the acquired Zener voltage. Next, the microcomputer 21 also turns off the switch unit 23. Then, the microcomputer 21 outputs a control signal that gives an operation permission to the switching regulator 20. Thereby, the switching regulator 20 starts an operation of supplying a drive current to the light source unit 2. Specifically, the switching regulator 20 increases or decreases the output voltage so that the set current value is obtained, and turns on each of the semiconductor light sources 10a to 10c.

  According to the present embodiment described above, the luminous intensity rank of each semiconductor light source is detected based on the voltage between terminals when a reverse voltage is applied, and the drive of an appropriate magnitude to be supplied to the semiconductor light source according to the detection result The current can be set. Therefore, it is not necessary to prepare a plurality of drive units (drive circuits) corresponding to the luminous intensity rank, and the problem of inventory and cost is solved.

  In addition, according to the present embodiment, it is possible to share a circuit unit for semiconductor light sources (light source units) having different luminous intensity ranks. That is, it is not necessary to replace the circuit unit according to the magnitude of the drive current or to manually adjust the drive current during manufacturing or repair. Thereby, even when one of the semiconductor light source (light source unit) or the circuit unit is replaced, a driving current suitable for the luminous intensity rank can be reliably supplied to the semiconductor light source without complicated operations.

  In addition, this invention is not limited to the content of embodiment mentioned above, In the range of the summary of this invention, it can change and implement variously. For example, in the embodiment described above, a vehicular lamp is cited as an example of the light source device according to the present invention, but the scope of application of the present invention is not limited to this.

  Further, in the above-described embodiment, the drive current corresponding to the luminous intensity rank of the semiconductor light source is set autonomously, but this may be performed manually. A schematic configuration of such a light source device is shown in FIG. A light source device 100b shown in FIG. 4 includes a light source device 1, a drive circuit 4 that supplies electric power to the light source device 1, and a harness 3 that connects them. The detailed configuration of the light source device 1 is as described above. The drive circuit 4 includes a current setting terminal, and is configured to be able to set a drive current according to the luminous intensity rank of each semiconductor light source of the light source unit 1 using the current setting terminal. Specifically, the drive circuit 4 includes, for example, a switching regulator and a storage unit (storage unit) that stores the magnitude of the drive current set using the current setting terminal (not shown). In the light source device 100b having this configuration, a reverse voltage is applied to the semiconductor light source of the light source unit 2 using, for example, an external device (not shown), and a voltage generated between the anode and the cathode of the semiconductor light source is detected at this time. And based on this detected voltage, the magnitude | size of the electric current which should be supplied to a semiconductor light source is set using the above-mentioned current setting terminal. In addition, what is necessary is just to set an electric current according to the luminous intensity rank, when the luminous intensity rank of each semiconductor light source of the light source part 2 is known beforehand.

  In addition, the component for autonomously setting the drive current according to the luminous intensity rank may be configured separately from the drive circuit. An example of such a configuration is shown in FIG. A light source device 100c shown in FIG. 5 connects between the light source device 1, a drive circuit 4a that supplies power to the light source device 1, a current setting circuit 5 that sets a drive current according to the luminous intensity rank, and these components. And a harness 3. The detailed configuration of the light source device 1 is as described above. The drive circuit 4a has a configuration similar to that of the drive circuit 4 described above. The current setting circuit 5 has a configuration in which the switching regulator 10 is omitted from the circuit unit 2 in the above-described embodiment. In the light source device 100 c having this configuration, the current setting circuit 5 is removed during normal use, and the light source device 1 and the drive circuit 4 a are directly connected via the harness 3. If necessary, the current setting circuit 5 is interposed between the light source device 1 and the drive circuit 4a, and the drive current is set in the drive circuit 4a. That is, a reverse voltage is applied to the semiconductor light source of the light source unit 2 using the current setting circuit 5, and a voltage generated between the anode and the cathode of the semiconductor light source at this time is detected. Based on the detected voltage, the magnitude of the current in the previous drive circuit 4a is set. By separately configuring the current setting circuit 5 in this manner, there is an advantage that the entire configuration of the light source device during normal use can be simplified. In addition, even for an existing light source device including a light source unit and a drive circuit, a drive current can be automatically set by interposing a current setting circuit therebetween.

  DESCRIPTION OF SYMBOLS 1 ... Light source part, 2 ... Circuit part, 3 ... Harness 10, 10a, 10b, 10c ... Semiconductor light source (including multichip), 11, 11a, 11b, 11c ... 1st Zener diode, 12, 12a, 12b, 12c ... 2nd Zener diode, 20 ... Switching regulator, 21 ... Microcomputer, 22 ... FET (transistor), 23 ... Switch part, 24 ... Resistance element, 100, 100a ... Light source device

Claims (4)

A semiconductor light source;
A first Zener diode having a first breakdown voltage and having a cathode connected to the anode of the semiconductor light source;
A second Zener diode having a second breakdown voltage less than the first breakdown voltage, an anode connected to the anode of the first Zener diode, and a cathode connected to the cathode of the semiconductor light source;
A voltage application unit for applying a reverse voltage to the semiconductor light source;
A voltage detection unit for detecting a voltage generated between an anode and a cathode of the semiconductor light source when the reverse voltage is applied to the semiconductor light source;
A current setting unit for setting a magnitude of a current to be supplied to the semiconductor light source based on the voltage detected by the voltage detection unit;
A light source device. A power control unit for controlling power supplied to the semiconductor light source;
The light source device according to claim 1, wherein the current setting unit sets the magnitude of the current by giving a predetermined control signal to the power control unit.   The light source device according to claim 2, wherein the power control unit starts supplying power to the semiconductor light source after the magnitude of the current is set by the current setting unit. (A) a semiconductor light source; (b) a first Zener diode having a first breakdown voltage and having a cathode connected to the anode of the semiconductor light source; and (c) a second smaller than the first breakdown voltage. And a second Zener diode having an anode connected to the anode of the first Zener diode and a cathode connected to the cathode of the semiconductor light source,
Applying a reverse voltage to the semiconductor light source;
A second step of detecting a voltage generated between an anode and a cathode of the semiconductor light source when the reverse voltage is applied to the semiconductor light source;
A third step of setting a magnitude of a current to be supplied to the semiconductor light source based on the voltage detected in the second step;
A method for controlling a light source device.

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