Light source device

The present application claims priority under 35 U. S. C. § 119 to Japanese Patent Application No. 2018-142221, filed Jul. 30, 2018. The contents of Japanese Patent Application No 2018-142221 are incorporated herein by reference in its entirety.

1. Field of the Invention

The present invention relates to a light source device that includes a plurality of light emitting elements.

2. Description of Related Art

In order to obtain light of a desired color from a light source device, a plurality of light emitting elements configured to emit light of different wavelength ranges can be discretely controlled. In that case, a separate wiring is required for at least one of the positive electrodes and a negative electrode of each of the light emitting elements, and further, a protective element is required for each of the light emitting elements.

One example of such a light source device includes a plurality of light emitting elements mounted on a common wiring, a protective element is mounted on each of the wirings corresponding to each of the light emitting elements, and an upper-surface-side electrode of each of the light emitting elements and an upper-surface-side electrode of each of the protective elements have the same polarity. In such a structure, components are needed to be spaced apart from one other to avoid short circuit between the wirings connected to the upper-surface-side electrodes of the light emitting elements and the wirings connected to the upper-surface-side electrodes of the protective elements. Accordingly, the substrate used in such a light source device needs to have a large area as a whole.

To accommodate this, a light source device has been proposed in which the protective elements and the light emitting elements are mounted with different polarities (for example, see Japanese Unexamined Patent Application Publication No. 2002-314146).

In the light source device described in Japanese Unexamined Patent Application Publication No. 2002-314146, the polarity of the upper-surface-side electrodes of the protective elements and the polarity of the upper-surface-side electrodes of the light emitting elements are different to each other, to allow mounting of the protective elements and the light emitting elements on the same wiring. With this, more efficient arrangement and wiring can be realized in terms of avoiding short circuit between the wires connected to the light emitting elements and the wires connected to the protective elements. However, an increase in the number of the light emitting elements mounted in the light source device increases the area of the wiring for mounting the light emitting elements and the protective elements, which requires insulating margins between the wirings. As a result, a large area is required for the substrate. This limits a reduction in the size of the light source device.

The present disclosure is devised to address such requirements, and it is hence an object thereof to provide a light source device of a small size in which the plurality of light emitting elements can be discretely controlled.

Accordingly, a light source device according to one embodiment of the present invention includes: at least one first wiring; a plurality of second wirings each corresponding to a respective one of the plurality of light emitting elements; a plurality of light emitting elements each having a top electrode and a bottom electrode, the bottom electrode connected to the at least one first wiring; a plurality of protective elements each having a top electrode and a bottom electrode, the bottom electrode connected to a respective one of the plurality of second wirings, and each connected to a respective one of the plurality of light emitting elements; a plurality of first wires each connecting the top electrode of each of the plurality of light emitting elements and a corresponding one of the plurality of second wirings; a plurality of second wires each connecting top electrodes of the plurality of protective elements; and at least one third wire connecting the top electrode of at least one protective element and the at least one first wiring. The top electrodes of the plurality of light emitting elements and the top electrodes of the plurality of protective elements have the same polarity, and the plurality of first wires are disposed at locations lower than the second wires.

As described above, the present disclosure can provide a light source device of a small size in which a plurality of light emitting elements can be discretely controlled.

FIG. 1 is a perspective view schematically showing a light source device according a first embodiment of the present invention.

FIG. 2 is a plan view schematically showing a light source device according the first embodiment of the present invention.

FIG. 3 is a cross-sectional view taken along line in FIG. 2 .

FIG. 4 is a circuit diagram showing a circuit configuration of a light source device according the first embodiment of the present invention.

FIG. 5 is a perspective view schematically showing a light source device according a second embodiment of the present invention.

FIG. 6 is a perspective view schematically showing a light source device according a third embodiment of the present invention.

FIG. 7 is a plan view schematically showing a light source device according the third embodiment of the present invention.

FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 7 .

FIG. 9 is a circuit diagram showing a circuit configuration of a light source device according the third embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings. It is to be FIG that the light source device described below is intended for implementing the technical concept of the present invention, and the present invention is not limited to those described below unless otherwise specified.

In the drawings, the same or similar portions or members may be assigned the same reference numerals. For the sake of easy understanding, different embodiments and examples may be illustrated, but partial replacement and/or combination of components illustrated in the embodiments and examples can be appropriately performed. Repetitive descriptions may be omitted in the embodiments and examples and differences may be illustrated. Similar effects obtained through similar structure may not be repeated in each of the embodiments and examples. In the drawings, the size, positional relationship and the like of the members may be exaggerated for clarity.

Light Source Device According to First Embodiment

A light source device according to a first embodiment of the present invention will be described with reference to FIG. 1 to FIG. 4 . FIG. 1 is a perspective view schematically showing a light source device according the first embodiment of the present invention. FIG. 2 is a plan view schematically showing a light source device according the first embodiment of the present invention, shown in FIG. 1 . FIG. 3 is a cross-sectional view taken along line in FIG. 2 . FIG. 4 is a circuit diagram showing a circuit configuration of a light source device according the first embodiment of the present invention. In the circuit diagram shown in FIG. 4 , a direction of the flow of electric current is indicated by arrows.

The light source device 2 according to the first embodiment includes a package 40 having a substrate 42 and a sidewall 44 formed along a periphery of the substrate 42 . In the first embodiment, the substrate 42 has a plate-like shape. The substrate 42 and the sidewall 44 can be formed integrally or a discrete substrate 42 and a discrete side wall 44 can be bonded to each other.

A plurality (six in the first embodiment) of light emitting elements 10 A to 10 F are disposed on the substrate 42 . An upward-reflecting mirror 50 having a light-reflecting surface 50 A configured to reflect light emitted from the light emitting elements 10 A to 10 F is disposed on the substrate 42 . Light emitted from the light emitting elements 10 A to 10 F are reflected at the light-reflecting surface 50 A in an upward direction substantially normal to the substrate 42 .

For the material of the substrate 42 , the lateral walls 44 , and the upward-reflecting mirror 50 , a known material such as glass, a single crystal or a polycrystal of silicon etc., a ceramic material, or a resin material can be used. Alternative to the upward-reflecting mirror 50 , the lateral wall 44 can be used as a light-reflecting surface to reflect light emitted from the light emitting elements 10 A to 10 F in an upward direction substantially normal to the upper surface of the substrate 42 .

The light source device 2 according to the first embodiment includes one or a plurality of (one in FIG. 1 to FIG. 4 ) first wiring 4 , and a plurality of (six in FIG. 1 to FIG. 4 ) second wirings 6 A to 6 on the substrate 42 . A plurality of (six in FIG. 1 to FIG. 4 ) light emitting elements 10 A to 10 F are mounted on the first wiring 4 . Each of the light emitting elements 10 A to 10 F has a P-electrode (positive electrode) as an upper-surface-side electrode, an N-electrode (negative electrode) as a lower-surface-side electrode, and the lower-surface-side electrode is connected to the first wiring 4 .

Further, the protective elements 20 A to 20 F each corresponding to respective one of the light emitting elements 10 A to 10 F are mounted on corresponding one of the second wirings 6 A to 6 F. Each of the protective elements 20 A to 20 F also has a P-electrode (positive electrode) as an upper-surface-side electrode, an N-electrode (negative electrode) as a lower-surface-side electrode, and the lower-surface-side electrode is connected to corresponding one of the second wirings 6 A to 6 F.

As described above, the upper-surface-side electrodes of the plurality of light emitting elements 10 A to 10 F and the plurality of protective elements 20 A to 20 F have the same polarity. In the first embodiment, the upper-surface-side electrodes are P-electrodes (positive electrodes), but the upper-surface-side electrodes of the plurality of light emitting elements 10 A to 10 F and the plurality of protective elements 20 A to 20 F may be N-electrodes (negative electrodes).

In the first embodiment, laser diodes are used as the light emitting elements 10 A to 10 F. For the laser diodes, nitride semiconductor laser elements to emit light in an ultraviolet to green light range, GaAs-based semiconductor laser elements to emit light in a red to infrared range can be used. With this arrangement, a light source device 2 having high luminance and high color reproductivity can be obtained.

For the light emitting elements, other than the laser diodes, any other appropriate light emitting elements such as light emitting diodes can also be used.

The protective elements 20 A to 20 F are for protecting the light emitting elements 10 A to 10 F from a surge current or static electricity, and Zener diodes are used in the first embodiment. As the protective elements, any other appropriate protective elements such as varistor elements, ESD suppressors, or arrestor elements can also be used.

The upper-surface-side electrodes of the light emitting elements 10 A to 10 F and corresponding second wirings 6 A and 6 F are respectively connected with corresponding first wires 30 A to 30 F. As will be described below, supplying electric power through the second wirings 6 A to 6 F, the light emitting elements 10 A to 10 F can be discretely caused to emit light.

The plurality of protective elements 20 A to 20 F are respectively corrected with the second wires 32 CA, 32 AB, 32 DF, and 32 FE. Further, the upper-surface-side electrode of at least one protective element ( 20 B and 20 E in the first embodiment) and the first wiring 4 are respectively connected with the third wires 34 B and 34 E. As will be described below, with this arrangement, even if a surge, static electricity, or a reverse current flows in the second wirings 6 A to 6 F, they can be prevented from flowing in the light emitting elements 10 A to 10 F.

As shown in FIG. 1 and FIG. 2 , in the first embodiment, three light emitting elements 10 A to 10 C and respectively corresponding protective elements 20 A to 20 C, and three light emitting elements 10 D to 10 F and respectively corresponding protective elements 20 D to 20 F are arranged substantially symmetrical and the wires are connected.

Light Emitting Elements 10 A to 10 C

In the description below, the three light emitting elements 10 A to 10 C and respectively corresponding protective elements 20 A to 20 C that are arranged in a lower side in FIG. 2 will be illustrated as the substantially symmetrically arranged components and corresponding wiring.

As for the light emitting element 10 A, the upper-surface-side electrode of the light emitting element 10 A and the second wiring 6 A are connected with the first wire 30 A. The lower-surface-side electrode of the light emitting element 10 A is connected to the first wiring 4 . When electric power is applied to the second wiring 6 A, electric current flows through the first wire 30 A to the upper-surface-side electrode (P-electrode) of the light emitting element 10 A, which then flows to the p-type cladding layer, the active layer, and the n-type cladding layer in this order, then from the lower-surface-side electrode (N-electrode) of the light emitting element 10 A flows to the first wiring 4 . Accordingly, the light emitting element 10 A can be discretely caused to emit light.

Similarly, as for the light emitting element 10 B, the upper-surface-side electrode of the light emitting element 10 B and the second wiring 6 B are connected with the first wire 30 B. The lower-surface-side electrode of the light emitting element 10 B is connected to the first wiring 4 . When electric power is applied to the second wiring 6 B, electric current flows through the first wire 30 B to the upper-surface-side electrode (P-electrode) of the light emitting element 10 B, which then flows to the p-type cladding layer, the active layer, and the n-type cladding layer in this order, then from the lower-surface-side electrode (N-electrode) of the light emitting element 10 B flows to the first wiring 4 . Accordingly, the light emitting element 10 B can be discretely caused to emit light.

Similarly, as for the light emitting element 10 C, the upper-surface-side electrode of the light emitting element 10 C and the second wiring 6 C are connected with the first wire 30 C. The lower-surface-side electrode of the light emitting element 10 C is connected to the first wiring 4 . When electric power is applied to the second wiring 6 C, electric current flows through the first wire 30 C to the upper-surface-side electrode (P-electrode) of the light emitting element 10 C, which then flows to the p-type cladding layer, the active layer, and the n-type cladding layer in this order, then from the lower-surface-side electrode (N-electrode) of the light emitting element 10 C flows to the first wiring 4 . Accordingly, the light emitting element 10 C can be discretely caused to emit light.

Next, the protective elements 20 A to 20 C will be described. The protective element 20 A corresponding to the light emitting element 10 A is mounted on the second wiring 6 A corresponding to the light emitting element 10 A, such that the lower-surface-side electrode (N-electrode) of the protective element 20 A is in contact with the second wiring 6 A. The protective element 20 B corresponding to the light emitting element 10 B is mounted on the second wiring 6 B corresponding to the light emitting element 10 B, such that the lower-surface-side electrode (N-electrode) of the protective element 20 B is in contact with the second wiring 6 B. The protective element 20 C corresponding to the light emitting element 10 C is mounted on are disposed second wiring 6 C corresponding to the light emitting element 10 C, such that the lower-surface-side electrode (N-electrode) of the protective element 20 C is in contact with the second wiring 6 C.

As shown in FIG. 1 and FIG. 2 , in the first embodiment, from the left side in the figures (the upward-reflecting mirror 50 -side), the second wiring 6 C corresponding to the light emitting element 10 C, the second wiring 6 A corresponding to the light emitting element 10 A, and the second wiring 6 B corresponding to the light emitting element 10 B are arranged in this order.

The upper-surface-side electrode (P-electrode) of the protective element 20 C located at the leftmost side and the upper-surface-side electrode (P-electrode) of the protective element 20 A located at the center are connected with the second wire 32 CA. The upper-surface-side electrode (P-electrode) of the protective element 20 A located at the center and the upper-surface-side electrode (P-electrode) of the protective element 20 B located at the rightmost side are connected with the second wire 32 AB. The upper-surface-side electrode (P-electrode) of the protective element 20 B located at the rightmost side and the first wiring 4 are connected with the third wire 34 B.

With this arrangement, if an overvoltage caused by static electricity or a reverse current occurs on the second wiring 6 C, electric current flows from the second wiring 6 C to the lower-surface-side electrode (N-electrode) of the protective element 20 C, and through the protective element 20 C, flows to the upper-surface-side electrode (P-electrode) of the protective element 20 C. The electric current flows from the upper-surface-side electrode (P-electrode) of the protective element 20 C through the second wire 32 CA to the upper-surface-side electrode (P-electrode) of the protective element 20 A, then from the upper-surface-side electrode (P-electrode) of the protective element 20 A, through the second wire 32 AB to the upper-surface-side electrode (P-electrode) of the protective element 20 B. Further, the electric current flows from the upper-surface-side electrode (P-electrode) of the protective element 20 B through the third wire 34 B to the first wiring 4 .

Electric current flows through the path of least resistance, such that the electric current which flows from the second wire 32 CA to the protective element 20 A will not flow into the protective element 20 A but will flow to the second wire 32 AB. Further, the electric current which flows from the second wire 32 AB to the protective element 20 B will not flow into the protective element 20 B but will flow to the third wire 34 B. With this arrangement, the light emitting elements 10 C can be reliably protected against reverse current.

With this arrangement, if a surge current or static electricity occurs on the second wiring 6 A, electric current flows from the second wiring 6 A to the lower-surface-side electrode (N-electrode) of the protective element 20 A, and through the protective element 20 A, flows to the upper-surface-side electrode (P-electrode) of the protective element 20 A. The electric current flows from the upper-surface-side electrode (P-electrode) of the protective element 20 A through the second wires 32 AB and 32 CA to the upper-surface-side electrode (P-electrode) of the protective element 20 B, then from the upper-surface-side electrode (P-electrode) of the protective element 20 B, through the third wire 34 B to the first wiring 4 .

Electric current flows through the path of least resistance, such that the electric current which flows from the second wire 32 AB to the protective element 20 B will not flow into the protective element 20 B but will flow to the third wire 34 B. Accordingly, the light emitting element 10 A can be reliably protected against reverse current.

With this arrangement, if a surge current or static electricity occurs on the second wiring 6 B, electric current flows from the second wiring 6 B to the lower-surface-side electrode (N-electrode) of the protective element 20 B, and through the protective element 20 B, flows to the upper-surface-side electrode (P-electrode) of the protective element 20 B. Further, the electric current flows from the upper-surface-side electrode (P-electrode) of the protective element 20 B through the third wire 34 B to the first wiring 4 . Accordingly, the light emitting element 10 B can be reliably protected against reverse current.

Wirings of Light Emitting Elements and Protective Elements

Next is described is a wiring structure of the light source device that includes a plurality of light emitting elements mounted on one or a plurality of wirings, a protective element corresponding to respective one of the light emitting elements mounted on a wiring corresponding to respective one of the light emitting elements, and the upper-surface-side electrodes of the light emitting elements and the upper-surface-side electrodes of the protective elements having the same polarity. Generally, in such a light source device, in order to avoid short circuit of the wires connecting the upper-surface-side electrodes of each of the light emitting elements and their respective corresponding wirings, and the wires connecting the upper-surface-side electrodes of each of the protective elements and one or a plurality of wirings, the components need to be spaced apart from one another. This configuration requires a large area such as the entire substrate.

On the other hand, in the first embodiment, the upper-surface-side electrodes of the plurality of protective elements 20 A to 20 C are connected with the second wires 32 A and 32 AB, and the upper-surface-side electrodes of the light emitting elements 10 A to 10 C and the second wirings 6 A to 6 C are respectively connected with the first wires 30 A to 30 C, such that the first wires 30 A to 30 C are arranged below the second wires 32 CA and 32 AB.

More specifically, the first wire 30 C connecting the upper-surface-side electrode of the light emitting element 10 C and the second wiring 6 C crosses under the second wire 32 CA connecting the upper-surface-side electrode of the protective element 20 C and upper-surface-side electrode of the protective element 20 A. Moreover, the first wire 30 A connecting the upper-surface-side electrode of the light emitting element 10 A and the second wiring 6 A and the first wire 30 B connecting the upper-surface-side electrode of the light emitting element 10 B and the second wiring 6 B cross under the second wire 32 AB connecting the upper-surface-side electrode of the protective element 20 A and upper-surface-side electrode of the protective element 20 B.

Further, of the protective elements 20 A to 20 C connected with each other at their upper-surface-side electrodes, the upper-surface-side electrode of the protective element 20 B located at a position with a lower possibility of short circuiting with other components and the first wiring 4 are connected with the third wire 34 B. With this arrangement, even if a surge current or static electricity occurs on any of the second wirings 6 A to 6 C, a reverse current can be diverted with the second wires 32 CA and 32 AB connecting the upper-surface-side electrodes of the protective elements 20 A to 20 C and the third wire 34 B connecting the upper-surface-side electrode of the protective element 20 B and the first wiring 4 , such that the reverse current can be bypassed to the first wiring 4 without flowing to the light emitting elements 10 A to 10 C.

As described above, according to the first embodiment, in the light source device 2 configured to discretely control a plurality of light emitting elements 10 A to 10 C, short circuit of wires can be efficiently prevented by spatially arranging the wires using the height of the protective elements 20 A to 20 C, even when the light emitting elements 10 A to 10 C mounted on the first wiring 4 and the protective elements 20 A to 20 C mounted on the second wirings 6 A to 6 C are closely arranged.

In particular, even when the first wiring 4 and the second wirings 6 A to 6 C are disposed on substantially a same plane, short circuit of wires can be reliably avoided due to the spatial arrangement of the wires using the height of the protective elements 20 A to 20 C.

If the protective elements 20 A to 20 C are not disposed at a lateral side with respect to the light emitting elements 10 A to 10 C, connecting the upper-surface-side electrodes of the protective elements 20 A to 20 C and the first wiring 4 with the wires becomes difficult. In particular, as in the first embodiment, when the upward-reflecting mirror 50 is disposed facing the light-emitting side of the lights 10 A to 10 F, a necessity may arise for disposing some of the protective elements such as the protective element 20 C at a lateral side with respect to the upward-reflecting mirror 50 . That is, the upward-reflecting mirror 50 is disposed facing the light-emitting side of the light emitting elements 10 A to 10 F, and at least one of the protective elements 20 A to 20 C (e.g., the protective element 20 C) is disposed at a lateral side with respect to the upward-reflecting mirror 50 . In this case, the upper-surface-side electrode of the protective element 20 C that is disposed at a lateral side with respect to the upward-reflecting mirror 50 and the first wiring 4 may become difficult to connect through a wire.

However, the upper-surface-side electrodes of the protective elements 20 A to 20 C are connected with the second wires 32 CA and 32 AB, and the upper-surface-side electrode of the protective element 20 B located at a position with low possibility of short circuit with the upward-reflecting mirror 50 and the light emitting elements 10 A to 10 C is connected to the first wiring 4 with the third wire 34 , such that even when a reverse current occurs on the second wiring 6 C, the reverse current flows through the protective element 20 C to the first wiring 4 , without flowing in the light emitting element 10 C.

In the first embodiment, the second wiring 6 C corresponds to the light emitting element 10 C located at an inward portion along a width direction of the substrate 42 is arranged at the leftmost side (i.e., the upward-reflecting mirror 50 -side) in the figure, but other appropriate arrangement can also be employed. Depending on the locations of the upper-surface-side electrodes of the light emitting elements and arrangement of other components, the second wiring 6 A (or 6 B) at an outer side and corresponding to the light emitting element 10 A (or 10 B) in FIG. 1 and FIG. 2 may be disposed leftmost (a lateral side with respect to the upward-reflecting mirror 50 ) in the figures. Accordingly, various spatial arrangements of the first wires and the second wires can be employed.

In the first embodiment, the upper-surface-side electrode of the protective element 20 B located rightmost in FIG. 2 and the first wiring 4 are connected with the third wire 34 B, but any other appropriate arrangement can be employed. According to the arrangement of the components, the upper-surface-side electrode of any protective element 20 and the first wiring 4 can be connected with the third wire 34 . If the arrangement of the components allows the use of wires, the upper-surface-side electrodes of the plurality of protective elements 20 and the first wiring 4 can be connected with a plurality of third wires 34 .

Also, in the first embodiment, a plurality of light emitting elements 10 A to 10 F are mounted on a single first wiring 4 , but each of the light emitting elements 10 may be mounted on a corresponding one of a plurality of first wirings. In such a case, connecting the upper-surface-side electrode of at least one protective element 20 and either one of the first wirings with the third wire 34 can release electric current that has flowed through any protective element 20 to the first wiring connected to the third wire 34 via the second wires 32 connecting the upper-surface-side electrodes of the protective elements 20 and the third wire 34 .

Light Emitting Elements 10 D to 10 F

Next, referring to FIG. 1 and FIG. 2 , the light emitting elements 10 D to 10 F and respectively corresponding protective elements 20 D to 20 F, which are arranged symmetric with respect to the light emitting elements 10 A to 10 C and respectively corresponding protective elements 20 A to 20 C will be described. The arrangement of the light emitting elements 10 D to 10 F and respectively corresponding protective elements 20 D to 20 F and corresponding wirings and function are similar to those described above.

More specifically, the light emitting element 10 D, the protective element 20 D, the second wiring 6 D, and the first wire 30 D respectively corresponds to the light emitting element 10 C, the protective element 20 C, the second wiring 6 C, and the first wire 30 C. Similarly, the light emitting element 10 F, the protective element 20 F, the second wiring 6 F, and the first wire 30 F respectively corresponds to the light emitting element 10 A, the protective element 20 A, the second wiring 6 A, and the first wire 30 A. Similarly, the light emitting element 10 E, the protective element 20 E, the second wiring 6 E, and the first wire 30 E respectively corresponds to the light emitting element 10 B, the protective element 20 B, the second wiring 6 B, and the first wire 30 B, described above.

Further, the second wire 32 DF corresponds to the second wire 32 CA described above, the second wire 32 FE corresponds to the second wire 32 AB described above, and the third wire 34 E corresponds to the third wire 34 B described above. Those wires have a similar function and configuration as described above and accordingly, repetitive description will be omitted.

Emission Wavelength of Light Emitting Element

The light source device 2 according to the first embodiment includes, for example, the light emitting elements 10 A and 10 B to emit light in a blue wavelength range, the light emitting elements 10 C and 10 D to emit light in a green wavelength range, and the light emitting elements 10 E and 10 F to emit light in a red wavelength range. In this case, a light source device of a small size configured to emit a white light can be realized by condensing the light reflected at the upward-reflecting mirror 50 in an upward direction substantially normal to the upper surface of the substrate 42 .

The protective elements 20 A and 20 B respectively corresponding to the light emitting elements 10 A and 10 B to emit light of a blue wavelength range are connected with the second wire 32 AB. The protective elements 20 F and 20 E respectively corresponding to the light emitting elements 10 F and 10 E to emit light of a red wavelength range are connected with the second wire 32 FE. In both cases, the upper-surface-side electrodes of the protective elements 20 corresponding to the light emitting elements 10 of the same emission wavelength range are connected with the second wires 32 .

Either when the light emitting elements 10 having the same emission wavelength range are discretely controlled or when the light emitting elements 10 having the same emission wavelength range are electrically connected with the second wires 6 and collectively controlled, if an electric current caused by a serge voltage or the like flows from the lower-surface-side electrodes of one or more protective elements 20 to the upper-surface-side electrodes thereof, the electric current will flow through the second wire(s) 32 and the third wire(s) 34 having smaller electric resistance to the first wiring(s) 4 , such that the light emitting elements 10 can be reliably protected.

The protective element 20 C corresponding to the light emitting element 10 C to emit light of a green wavelength range and the protective element 20 A corresponding to the light emitting elements 10 A to emit light of a blue wavelength range are connected with the second wire 32 CA. The protective element 20 D corresponding to the light emitting element 10 D to emit light of a green wavelength range and the protective element 20 F corresponding to the light emitting elements 10 F to emit light of a red wavelength range are connected with the second wire 32 DF. In both cases, the upper-surface-side electrodes of the protective elements 20 corresponding to the light emitting elements 10 of the different emission wavelength ranges are connected with the second wires 32 .

If an electric current caused by a serge voltage or the like flows from the lower-surface-side electrodes of one or more protective elements 20 to the upper-surface-side electrodes thereof, the electric current will flow through the second wire(s) 32 and the third wire(s) 34 having smaller electric resistance to the first wiring(s) 4 , such that even when the upper-surface-side electrodes of the protective elements 20 respectively corresponding to the light emitting elements 10 having different emission wavelength ranges are connected, the light emitting elements 10 can be reliably protected.

In particular, the light emitting element 10 D to emit light in a green wavelength range is a nitride semiconductor laser and the light emitting element 10 F to emit light in a red wavelength range is a GaAs-based semiconductor laser element. That is, the second wire 32 DF connecting the protective element 20 D corresponding to the light emitting element 10 D to emit light in a green wavelength range and the protective element 20 F corresponding to the light emitting element 10 F to emit light in a red wavelength range is indirectly connecting light emitting element 10 D and the light emitting element 10 F with different semiconductor materials.

Even in this case, if an electric current caused by a serge voltage or the like flows from the lower-surface-side electrodes of one or more protective elements 20 to the upper-surface-side electrodes thereof, the electric current will flow through the second wire(s) 32 and the third wire(s) 34 having smaller electric resistance to the first wiring(s) 4 , such that even when the upper-surface-side electrodes of the protective elements 20 respectively corresponding to the light emitting elements 10 with different semiconductor materials are connected, the light emitting elements 10 can be reliably protected.

Further, a single light emitting element 10 may have a plurality of light emitting points. In this case, the light source device 2 of a small size that can emit light of more various emission wavelength ranges can be realized. In this case, a single light emitting element 10 preferably has a plurality of electrodes. Accordingly, more efficient wiring can be realized and thus the light source device 2 of a small size that nevertheless emits light of more various emission wavelength ranges can be realized.

Light Source Device According to Second Embodiment

Next, with reference to FIG. 5 , the light source device according to a second embodiment of the present invention will be described. FIG. 5 is a perspective view schematically showing a light source device according a second embodiment of the present invention.

The light source device 2 ′ shown in FIG. 5 differs from the light source device 2 according to the first embodiment described above, in which a step portion 46 having an upper surface located higher than the upper surface of the substrate 42 is provided at both lateral sides in the width direction in the package 40 ′.

The first wiring 4 is disposed on the upper surface of the substrate 42 and a plurality of light emitting elements 10 A to 10 F are mounted on the first wiring 4 . The second wirings 6 A to 6 F are disposed on the upper surfaces of the step portions 46 that are located higher than the upper surface of the substrate 42 , and the protective elements 20 A to 20 F are respectively mounted on a corresponding one of the second wirings 6 A to 6 F.

As shown in FIG. 5 , in the second embodiment, three light emitting elements 10 A to 10 C and respectively corresponding protective elements 20 A to 20 C, and three light emitting elements 10 D to 10 F and respectively corresponding protective elements 20 D to 20 F are arranged substantially symmetrical and the wires are connected. The protective elements 20 A to 20 B respectively corresponding to the light emitting elements 10 A to 10 D are disposed on the upper surface of one of the two step portions 46 and the protective elements 20 D to 20 D respectively corresponding to the light emitting elements 10 D to 10 F are disposed on the upper surface of the other one of the two step portions 46 .

In the second embodiment, the plurality of first wires 30 C and 30 D are not disposed below the corresponding one of the plurality of second wires. Although illustrated as above, other appropriate configurations can also be employed. For example, the second wirings 6 C and 6 D and the protective elements 20 C and 20 D can be arranged at a lateral side with respect to the upward-reflecting mirror 50 , and similar to the light source device 2 according to the first embodiment, the first wires 30 C and 30 D are arranged crossing under the second wires 32 CA and 32 DF.

In the second embodiment, due to the step portions 46 , the locations of the second wirings 6 A to 6 F are higher than the first wiring 4 , which facilitates arranging the first wires 30 A, 30 B, 30 E, and 30 F passing under the second wires 32 CA, 32 AB, 32 DF, and 32 FE.

Moreover, the first wires 30 A to 30 F pulled up from the upper-surface-side electrodes of the light emitting elements 10 A to 10 F are not needed to be largely pulled downward to connect to the second wirings 6 A to 6 F, which can reduce the degree of curving of the wires and thus wiring of high reliability can be realized. Similarly, this configuration can eliminate the need of largely pulling up of the second wires 32 CA, 32 AB, 32 DF, and 32 FE from the upper-surface-side electrodes of the protective elements 20 A to 20 F to avoid short circuit with the first wire, such that the degree of curving of the second wires can also be reduced, thus wiring of high reliability can be realized.

Light Source Device According to Third Embodiment

Next, with reference to FIG. 6 to FIG. 9 , the configuration of the light source device according to a second embodiment of the present disclosure will be described. FIG. 6 is a perspective view schematically showing a light source device according a third embodiment of the present invention. FIG. 7 is a plan view schematically showing a light source device according the third embodiment of the present invention. FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 7 . FIG. 9 is a circuit diagram showing a circuit configuration of a light source device according the third embodiment of the present invention. In the circuit diagram shown in FIG. 9 , the flow of electric current (from upper side to lower side in the figure) is shown by arrows.

The light source device 2 ″ according to the third embodiment includes the package 40 and the upward-reflecting mirror 50 having structures similar to those in the light source device 2 according to the first embodiment. In the third embodiment, six light emitting elements 10 P to 10 U can also be discretely controlled, and as shown in FIG. 6 and FIG. 7 , three light emitting elements 10 P to 10 R and respectively corresponding protective elements 20 P to 20 R, and three light emitting elements 10 S to 10 U and respectively corresponding protective elements 20 S to 20 U are arranged substantially symmetrical and the wires are connected.

Light Emitting Elements 10 P to 10 R

In the description below, the three light emitting elements 10 P to 10 R and respectively corresponding protective elements 20 P to 20 R that are arranged in a lower side in FIG. 7 will be illustrated as the substantially symmetrically arranged components and corresponding wiring.

The configuration of the two light emitting elements 10 P and 10 Q and their corresponding protective elements 20 P and 20 Q are similar to those in the first embodiment. The lower-surface-side electrodes of the light emitting elements 10 P and 10 Q are connected to the first wiring 4 , and the lower-surface-side electrodes of the protective elements 20 P and 20 Q are respectively connected to the second wiring 6 P and 6 Q corresponding to the light emitting elements 10 P and 10 Q. The upper-surface-side electrodes of the light emitting elements 10 P and 10 Q and the upper-surface-side electrodes of the protective elements 20 P and 20 Q have the same polarity (P-electrodes).

The first wire 30 P connecting the upper-surface-side electrode of the light emitting element 10 P and the second wiring 6 P crosses below the second wire 32 PQ connecting the upper-surface-side electrode of the protective element 20 P and upper-surface-side electrode of the protective element 20 Q. Similarly, the first wire 30 Q connecting the upper-surface-side electrode of the light emitting element 10 Q and the second wiring 6 Q crosses below the second wire 32 PQ connecting the upper-surface-side electrode of the protective element 20 P and upper-surface-side electrode of the protective element 20 Q. The upper-surface-side electrode of the protective element 20 Q and the first wiring 4 are connected with the third wires 34 Q.

Accordingly, the light emitting element 10 P and the light emitting element 10 Q can be discretely caused to emit light. Further, if a surge current or static electricity occurs on the second wiring 6 P, electric current flows from the second wiring 6 P to the lower-surface-side electrode (N-electrode) of the protective element 20 P, and through the protective element 20 P, flows to the upper-surface-side electrode (P-electrode) of the protective element 20 P. Then, the electric current flows from the upper-surface-side electrode (P-electrode) of the protective element 20 P through the second wire 32 PQ to the upper-surface-side electrode (P-electrode) of the protective element 20 Q, then from the upper-surface-side electrode (P-electrode) of the protective element 20 Q, flows through the third wire 34 Q to the first wiring 4 .

With this arrangement, if a surge current or static electricity occurs on the second wiring 6 Q, electric current flows from the second wiring 6 Q to the lower-surface-side electrode (N-electrode) of the protective element 20 Q, and through the protective element 20 Q, flows to the upper-surface-side electrode (P-electrode) of the protective element 20 Q. Then, the electric current flows from the upper-surface-side electrode (P-electrode) of the protective element 20 Q through the third wire 34 Q to the first wiring 4 . With this arrangement, the light emitting elements 10 P and 10 Q can be reliably protected against reverse current.

The lower-surface-side electrode of the light emitting element 10 R is connected to the first wiring 4 , and the upper-surface-side electrode of the light emitting element 10 R is a P-electrode as that of the light emitting elements 10 P and 10 Q. Meanwhile, the protective element 20 R corresponding to the light emitting element 10 R differs from that in the first embodiment. The upper-surface-side electrode of the protective element 20 R is an N-electrode having a reverse polarity, and the protective element 20 R is mounted on the first wiring 4 with the lower-surface-side electrode connected to the first wiring 4 .

The upper-surface-side electrode of the light emitting element 10 R and the upper-surface-side electrode of the protective element 20 R are connected with a fourth wire 36 R, and the upper-surface-side electrode of the protective element 20 R and a discrete wiring 8 R corresponding to the light emitting element 10 R are connected with a fifth wire 38 R.

When electric power is applied to the discrete wiring 8 R, electric current flows through the fifth wire 38 R to the upper-surface-side electrode of the protective element 20 R, then from the upper-surface-side electrode of the protective element 20 R, through the fourth wire 36 R, flows to the upper-surface-side electrode (P-electrode) of the light emitting element 10 R. Further, from the upper-surface-side electrode (P-electrode) of the light emitting element 10 R, the electric current flows to the P-type cladding layer, the active layer, and the N-type cladding layer in this order, and from the lower-surface-side electrode of the light emitting element 10 R flows to the first wiring 4 . Accordingly, the light emitting element 10 R can be discretely caused to emit light.

With this arrangement, if a surge current or static electricity occurs on the discrete wiring 8 R, electric current flows from the discrete wire 8 R, through the fifth wire 38 R, to the upper-surface-side electrode (N-electrode) of the protective element 20 R, and through the protective element 20 P, flows to the lower-surface-side electrode (P-electrode) to the first wiring 4 . With this arrangement, the electric current can be released to the first wiring 4 without a reverse current flows in the light emitting element 10 R.

As described above, in the third embodiment, the light emitting element 10 R mounted on the first wiring 4 and the protective element 20 R of a reverse polarity are provided in addition to the light emitting elements 10 P and 10 Q mounted on the first wiring 4 and the present embodiments 20 P and 20 Q respectively mounted on the second wirings 6 P and 6 Q, thus realizing the light source device 2 ″ of a small size in which, although having light emitting elements of various emission wavelength ranges, short circuit among wires is effectively avoided.

Light Emitting Elements 10 S to 10 U

Next, referring to FIG. 6 and FIG. 7 , the light emitting elements 10 S to 10 U and respectively corresponding protective elements 20 S to 20 U, which are arranged symmetric with respect to the light emitting elements 10 P to 10 R and respectively corresponding protective elements 20 P to 20 R will be described. The arrangement of the light emitting elements 10 P to 10 R and respectively corresponding protective elements 20 P to 20 R and corresponding wirings and function are similar to those described above.

More specifically, the light emitting element 10 U, the protective element 20 U, the second wiring 6 U, and the first wire 30 U respectively corresponds to the light emitting element 10 P, the protective element 20 P, the second wiring 6 P, and the first wire 30 P. Similarly, the light emitting element 10 T, the protective element 20 T, the second wiring 6 T, and the first wire 30 T respectively corresponds to the light emitting element 10 Q, the protective element 20 Q, the second wiring 6 Q, and the first wire 30 Q.

Similarly, the light emitting element 10 S, the protective element 20 S, the discrete wiring 8 S, the fourth wire 36 S, and the fifth wire 38 S respectively corresponds to the light emitting element 10 R, the protective element 20 R, the discrete wiring 8 R, the fourth wire 36 R, and the fifth wire 38 R. Further, the second wire 32 UT corresponds to the second wire 32 PQ described above, and the third wire 34 T corresponds to the third wire 34 Q described above. The configuration of those are similar to that described above and accordingly, repetitive description will be omitted.

As described above, the light source devices 2 , 2 ′, and 2 ″ according to the embodiments include, at least one first wiring 4 ; a plurality of second wirings 6 ; a plurality of light emitting elements 10 each having a lower-surface-side electrode connected to a respective one of the at least one first wiring 4 ; a plurality of protective elements 20 each having a lower-surface-side electrode connected to a respective one of the plurality of second wirings 6 each corresponding to a respective one of the plurality of light emitting elements 10 , each of the plurality of protective elements 20 connected to a respective one of the plurality of light emitting elements 10 ; a plurality of first wirings 4 each connecting an upper-surface-side electrode of each of the plurality of light emitting elements 10 and a respective one of the plurality of second wirings 6 ; a plurality of second wires 32 each connecting the upper-surface-side electrodes of two adjacent ones of the protective elements 20 ; and a plurality of third wires 34 each connecting an upper-surface-side electrode of a respective one of the plurality of protective elements 20 and a corresponding one of the at least one first wiring 4 . The upper-surface-side electrodes of the plurality of light emitting elements 10 and the upper-surface-side electrodes of the plurality of protective elements 20 are of a same polarity, and the plurality of first wires 30 are disposed below the plurality of second wires 32 .

With the arrangement described above, in the light source devices 2 , 2 ′, and 2 ″ respectively configured to discretely control a plurality of light emitting elements 10 , short circuit of wires 30 , 32 , 34 can be efficiently prevented by spatially arranging the wires by using the height of the protective elements 20 , even when the light emitting elements 10 mounted on the first wiring 4 and the protective elements 20 respectively mounted on the second wirings 6 are closely arranged, and accordingly, can provide the light source devices 2 , 2 ′, and 2 ″ of a small size in which a plurality of light emitting elements 10 can be discretely controlled.

While the present invention has been described according to the embodiments and the aspects with certain degrees of details, contents of disclosure of the embodiments and aspects shall be varied in details of the configuration, and the combination of elements and the change of order in the embodiments and aspects can be realized without deviating from the scope of the claims and contents of the present invention.