Wiring Substrate and Light Irradiation Device

Abstract

To provide a light irradiation device having a plurality of LED lighting circuits, capable of preventing size increase and optical performance decrease and further, suppressing low lighting, while reducing restrictions on design.SOLUTION: A wiring board on which a plurality of LEDs are mounted includes at least two wiring patterns which are insulated from each other to supply power to the plurality of LEDs. The two wiring patterns have parts overlapping with each other in plan view. The wiring board is configured so that, in the overlapping parts, one wiring pattern straddles the other wiring pattern through a jumper wire.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a wiring board and a light irradiation device using the same.

Background Art

[0002] Conventionally, as a light irradiation device using LEDs, there are those that can independently light LEDs of a plurality of different emission colors, and so-called divided emission types in which the emission surface is divided into a plurality of dimmable emission regions (for example, Patent Document 1). In such a light irradiation device, since the circuit configuration becomes complicated, wiring patterns of a plurality of LED lighting circuits corresponding to each emission color and each emission region may be formed on both sides of the wiring board.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the light irradiation device in which a plurality of wiring patterns are formed on both sides of the wiring board as described above, when power is supplied to a certain LED lighting circuit to light the LED, so-called micro-lighting may occur in which the LEDs of other LED lighting circuits in the vicinity are also inadvertently lit slightly.

[0005] The cause of such micro-lighting is that when a plurality of wiring patterns overlap each other with an insulator such as a base board interposed therebetween in the wiring board, the portion functions as a capacitor that stores electric charges, generating a stray capacitance. As a result, when power is supplied to one wiring pattern, electricity may also flow unintentionally to other wiring patterns.

[0006] Therefore, in order to solve the problem of micro-illumination, for example, it is conceivable to form a plurality of wiring patterns on the same surface of the wiring board and design them so that the wiring patterns are detoured so as not to be close to each other. However, in this case, the size of the wiring board becomes large, and there is a problem that it is difficult to apply it to a product with a small size.

[0007] In addition, since it is necessary to increase the distance between the LEDs in order to secure the wiring pattern area, there is a problem that optical performance such as uniformity deteriorates. Also, by using lead wiring to detour without detouring the wiring patterns from each other, the size of the wiring board can be suppressed. However, in this case, there is a problem that the housing size increases in order to secure the installation space for the lead wiring.

[0008] Also, by connecting the power cable from each divided position of the divided light-emitting region, the overlap of the wiring patterns on the wiring board is eliminated. However, a plurality of power cables come out from different locations on the wiring board, resulting in unnecessary restrictions in designing the device.

[0009] The present invention has been made to solve the above problems at once. In an optical irradiation device having a plurality of LED lighting circuits, the main problem is to suppress micro-illumination without increasing the size, without degrading the optical performance, and with fewer design constraints.

Means for Solving the Problems

[0010] That is, the wiring board of the present invention is one on which a plurality of LEDs are mounted, and includes at least two insulated wiring patterns for energizing the plurality of LEDs. The two wiring patterns have an overlapping portion that overlaps each other in a plan view. In the overlapping portion, one of the wiring patterns is configured to straddle the other wiring pattern via a jumper wire. Note that "plan view" means viewing from a direction perpendicular to the LED mounting surface of the wiring board.

[0011] Further, the light irradiation device of the present invention is characterized by comprising the wiring board and a plurality of LEDs mounted on the wiring board.

[0012] According to the wiring board and the light irradiation device configured as described above, in the overlapping portion, one wiring pattern straddles the other wiring pattern via a jumper wire, so that the distance between the two wiring patterns in the overlapping portion can be increased, and an air layer with a low dielectric constant can be provided therebetween. As a result, the stray capacitance formed in the overlapping portion can be reduced without detouring the wiring pattern on the wiring board, so that the occurrence of micro-illumination can be suppressed without increasing the size (area) of the wiring board.

[0013] Further, in the overlapping portion of the wiring board, it is preferable that the two wiring patterns intersect each other. In this way, the area where the two wiring patterns overlap can be reduced, so that the stray capacitance formed therebetween can be made smaller, and the occurrence of micro-illumination can be more effectively suppressed.

[0014] As a specific embodiment of the wiring board, in the overlapping portion, the two wiring patterns are respectively formed on different planes shifted in the thickness direction of the wiring board. In this way, since the two wiring patterns are formed on different planes of the wiring board, the degree of freedom in handling each wiring pattern can be increased.

[0015] Further, as another specific embodiment of the wiring board, in the overlapping portion, it is preferable that both of the two wiring patterns are formed on the same plane of the wiring board. That is, in this case, the two wiring patterns overlap with each other through only an air layer without sandwiching an insulator such as a base substrate. By doing so, since an insulator having a dielectric constant larger than that of air is not interposed therebetween, the parasitic capacitance formed between the two wiring patterns can be reduced, and the occurrence of micro-illumination can be effectively suppressed. Further, if the two overlapping wiring patterns are provided only on the same plane of the wiring substrate, the wiring substrate can be a single-sided single-layer substrate instead of a double-sided substrate or a multilayer substrate. Therefore, the base substrate constituting the wiring substrate can be made of, for example, aluminum having a high thermal conductivity, and the heat dissipation performance can be improved by closely attaching the back surface to a housing or the like.

[0016] Further, as an aspect in which the effects of the wiring substrate and the light irradiation device of the present invention described above are remarkably exhibited, in the wiring substrate, an aspect in which the two wiring patterns are supplied with current from a common power supply device can be mentioned. In such a case, each LED lighting circuit constituted by the two overlapping wiring patterns becomes common inside the power supply device. Therefore, when the parasitic capacitance between the two overlapping wiring patterns is large, the above-described problem of micro-illumination is likely to occur.

[0017] As a specific aspect of the wiring substrate described above, the two wiring patterns are for energizing a plurality of LEDs having mutually different emission colors, or for energizing a plurality of LEDs mounted in mutually divided different regions.

Advantages of the Invention

[0018] According to the present invention configured as described above, in a light irradiation device having a plurality of LED lighting circuits, it is possible to suppress micro-illumination without increasing the size, without degrading the optical performance, and with fewer design constraints.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 6

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Figure 8

Mode for Carrying Out the Invention

[0020] Hereinafter, an embodiment of a light irradiation device 100 according to the present invention will be described with reference to the drawings.

[0021] The light irradiation device 100 of the present embodiment is, for example, for performing surface inspection of a workpiece, mark detection, etc. Specifically, as shown in FIGS. 1 and 2, for example, a plurality of LEDs 1 are laid concentrically on the bottom surface, and the bottom surface (light emitting surface) is configured to emit surface light in a ring shape. And this light irradiation device 100 irradiates light to the workpiece by bringing its bottom surface close to the workpiece in order to perform surface inspection or mark detection of the workpiece. An observation hole H penetrates through the center of this illumination device, and imaging or visual observation of the workpiece surface illuminated through this observation hole H can be performed. This light irradiation device 100 is configured to be supplied with power from a power supply device (not shown) and to be able to selectively irradiate light of different colors (for example, red, blue, green, etc.).

[0022] Specifically, this light irradiation device 100 includes a plurality of LEDs 1, a wiring board 2 (mounting board) on which the plurality of LEDs 1 are mounted, and a housing 3 that houses this wiring board 2.

[0023] The LED1s are arranged on the wiring board 2 at substantially equal intervals. In the present embodiment, bullet-shaped LED1s are used, but for example, SMD type or chip type ones may be used, and their structures are not limited in any way. The light irradiation device 100 of the present embodiment includes a plurality of LED1s of a plurality of types (for example, red, blue, green, etc.) having mutually different emission colors, with a plurality of each type.

[0024] The wiring board 2 includes an insulating base board 21 and a plurality of wiring patterns 22 formed on the base board 21. The wiring board 2 of the present embodiment is a double-sided board (two-layer board) with wiring patterns 22 formed on both sides of the base board 21.

[0025] The base board 21 is configured such that at least its surface has insulation properties. Here, the base board 21 is a flexible board such as a resin board having flexibility made of, for example, polyimide resin. Note that the base board 21 is not limited to this, and it may be one in which an insulating layer is formed on the surface of an aluminum base material on a thin plate.

[0026] The wiring pattern 22 is for energizing the LED1 and is mainly composed of a conductive foil 221 such as a copper foil formed on the surface of the base board 21. The wiring board 2 includes a plurality of wiring patterns 22 corresponding to a plurality of LED1s having mutually different emission colors, and these plurality of wiring patterns 22 are insulated from each other on the base board 21. These plurality of wiring patterns 22 are formed on the base board 21 so as to overlap each other at one or a plurality of locations in a plan view.

[0027] The plurality of wiring patterns 22 and the plurality of LEDs 1 electrically connected thereto constitute a plurality of LED lighting circuits 4 that can be lit independently of each other (divided from each other within the light irradiation device 100). As shown in FIG. 3, in each LED lighting circuit 4, a plurality of LED groups each consisting of a plurality of LEDs 1 connected in series to each other are connected in parallel. The plurality of LEDs 1 included in each LED lighting circuit 4 have the same emission color as each other. And each LED lighting circuit 4 is configured to be connected to a common power supply device 200 and supplied with current, and the positive side is common inside the power supply device 200.

[0028] Thus, in order to suppress the occurrence of micro-lighting, the light irradiation device 100 of the present embodiment has, as shown in FIGS. 4 to 7, two wiring patterns 22 having overlapping portions 5 that overlap each other in a plan view among the plurality of wiring patterns 22. One wiring pattern 22 straddles the other wiring pattern 22 in the overlapping portion 5 via a jumper wire 222, so that an air layer S is provided between the two wiring patterns 22.

[0029] More specifically, in the overlapping portion 5 of the wiring pattern 22 with other wiring patterns 22, conductive foils 221 such as copper foils are separated from each other, and the mutually separated conductive foils 221 are connected by a jumper wire 222. Specifically, the jumper wire 222 is a component such as a wire or a pin that electrically connects the mutually separated wiring patterns 22, and short-circuits between the separated conductive foils 221 to electrically connect them. Specifically, this jumper wire 222 has an extremely low resistance value (for example, 8 mΩ or less) and has a larger allowable current value (for example, 2 A or more) than general lead wiring. The jumper wire 222 includes, for example, a substrate made of phosphor bronze and having a nickel underlayer tin plating treatment on its surface.

[0030] The jumper wire 222 is set such that its length is at least longer than the overlapping portion 5, one end of which is connected to one (positive side) of the conductive foils 221 separated from each other, and the other end is connected to the other (negative side) of the conductive foil 221. Further, the jumper wire 222 is configured to float at a certain distance (for example, about 0.5 mm) from the surface of the base substrate 21 at least in the overlapping portion 5.

[0031] In the wiring substrate 2 of the present embodiment, in the overlapping portion 5, the modes in which one wiring pattern 22 straddles the other wiring pattern 22 via the jumper wire 222 include those shown in FIGS. 4 to 7.

[0032] In the modes shown in FIGS. 4(a) and 4(b), two overlapping wiring patterns 22 are respectively formed on different planes shifted in the thickness direction of the wiring substrate 2, and the two wiring patterns 22 intersect each other in a plan view. Specifically, the two wiring patterns 22 are formed on both surfaces (the front surface 21a and the back surface 21b) of the base substrate 21, and are formed so as to intersect and overlap each other in a plan view. And in this case, a part of the wiring pattern 22 formed on one of the front surface 21a and the back surface 21b is constituted by the jumper wire 222 so as to move away from the other wiring pattern 22 in the overlapping portion 5. Also, both wiring patterns 22 may be constituted by the jumper wire 222 in the overlapping portion 5. In this case, in the overlapping portion 5, an air layer S and the base substrate 21 are provided between the two wiring patterns 22.

[0033] In the embodiments shown in FIGS. 5(a) and 5(b), two overlapping wiring patterns 22 are formed on the same plane of the wiring substrate 2, and the two wiring patterns 22 intersect each other in a plan view. Specifically, both of the two wiring patterns 22 are formed on one side of the base substrate 21, and are formed so as to intersect and overlap each other in a plan view. Here, in the overlapping portion 5, a part of one wiring pattern 22 is constituted by a jumper wire 222 so as to be away from the other wiring pattern 22. In this case, only an air layer S is provided between the two wiring patterns 22 in the overlapping portion 5.

[0034] In the embodiments shown in FIGS. 6(a) and 6(b), two overlapping wiring patterns 22 are formed on different planes shifted in the thickness direction of the wiring substrate 2, and the two wiring patterns 22 are formed so as to extend along substantially the same direction as each other in a plan view. Specifically, in the two wiring patterns 22 formed on both surfaces (the front surface 21a and the back surface 21b) of the base substrate 21 and extending along substantially the same direction as each other, one wiring pattern 22 has a detour portion that bypasses, for example, a through hole T formed in the base substrate 21, and this detour portion overlaps with the other wiring pattern 22. In this case, a part of the other wiring pattern 22 having no detour portion may be constituted by a jumper wire 222 so as to be away from the detour portion of the one wiring pattern 22 in the overlapping portion 5.

[0035] Also, in the embodiments shown in FIGS. 7(a) and 7(b), two overlapping wiring patterns 22 are formed on the same plane of the wiring substrate 2, and the two wiring patterns 22 are formed so as to extend along substantially the same direction as each other in a plan view. Both of the two wiring patterns 22 extending along substantially the same direction as each other are formed on one side of the base substrate 21.

[0036] According to the wiring board 2 and the light irradiation device 100 of the present embodiment configured as described above, in the overlapping portion 5, since one wiring pattern 22 straddles the other wiring pattern 22 via the jumper wire 222, the distance between the two wiring patterns 22 in the overlapping portion 5 can be increased, and an air layer S having a low dielectric constant can be provided therebetween. As a result, the parasitic capacitance formed in the overlapping portion 5 can be reduced without detouring the wiring pattern 22 on the base substrate 21, so that the generation of micro-lighting can be suppressed without increasing the size (area) of the wiring board 2.

[0037] <Other Embodiments> Note that the present invention is not limited to the above-described embodiment.

[0038] The wiring board 2 of the above embodiment includes all the modes shown in FIGS. 4 to 7 in such a mode that one wiring pattern 22 straddles the other wiring pattern 22 via the jumper wire 222 in the overlapping portion 5, but is not limited thereto. The wiring board 2 of other embodiments may include only some of the modes described in FIGS. 4 to 7 in the overlapping portion.

[0039] For example, the wiring board 2 of the above embodiment is a double-sided board (two-layer board) in which the wiring patterns 22 are formed on both sides of the base substrate 21, but is not limited thereto. The wiring board 2 of other embodiments may be a multilayer board such as a four-layer board or a six-layer board, or may be a single-sided one-layer board. When the wiring board 2 is a multilayer board, for example, as shown in FIG. 8, two overlapping wiring patterns 22 are formed on different planes shifted in the thickness direction of the wiring board 2, and one of the two wiring patterns may be formed on the surface of the wiring board 2 and the other may be formed in the inner layer of the base substrate 21.

[0040] In the above-described embodiment, the light irradiation device 100 is configured to be able to selectively irradiate light of different colors, and the plurality of wiring patterns 22 formed on the wiring substrate 2 are for energizing a plurality of types of LEDs 1 having mutually different emission colors, but it is not limited thereto. Each wiring pattern 22 only needs to be configured such that the LED lighting circuits 4 formed thereby are divided from each other within the light irradiation device 100.

[0041] In another embodiment, the light irradiation device 100 may be a so-called divided emission type in which the light emission surface formed by the plurality of LEDs 1 is divided into a plurality of individually dimmable light emission regions. In this case, the plurality of wiring patterns 22 may be formed on the wiring substrate 2 so as to energize the LEDs 1 mounted on the corresponding light emission regions, respectively.

[0042] Also, the light irradiation device 100 of the above-described embodiment has a light emission surface formed in a ring shape, but it is not limited thereto. In other embodiments, the light emission surface may be rectangular or other shapes.

[0043] Needless to say, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit thereof.

Explanation of Reference Numerals

[0044] 100 ··· Light irradiation device 1 ··· LED 2 ··· Wiring substrate 21 ··· Base substrate 22 ··· Wiring pattern 221 ··· Conductive foil 222 ··· Jumper wire 4 ··· Lighting circuit 5 ··· Overlapping portion

Claims

1. A wiring board on which a plurality of LEDs are mounted, comprising at least two insulated wiring patterns for energizing the plurality of LEDs, the two wiring patterns having an overlapping portion that overlaps with each other in a plan view, and in the overlapping portion, one of the wiring patterns is configured to straddle the other wiring pattern via a jumper wire, A wiring board in which, in the overlapping portion, the two wiring patterns are formed on different planes shifted in the thickness direction of the wiring board.

2. The wiring board according to claim 1, wherein, in the overlapping portion, the two wiring patterns intersect each other.

3. The wiring board according to claim 1 or 2, wherein the two wiring patterns are supplied with current from a common power supply device.

4. The wiring board according to any one of claims 1 to 3, wherein the two wiring patterns are for energizing a plurality of LEDs having mutually different emission colors, or for energizing a plurality of LEDs mounted in mutually divided different regions.

5. An optical irradiation device comprising the wiring board according to any one of claims 1 to 4 and a plurality of LEDs mounted on the wiring board.

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