Inspection light irradiation device

Abstract

To provide a light irradiation device 100 for inspection capable of realizing both drastic reduction in thickness and improvement in heat radiation.SOLUTION: A light irradiation device for inspection comprises: a housing 1 having an observation hole 1a for inspection that penetrates in a thickness direction; a first substrate 2 arranged around the observation hole 1a; and a plurality of LEDs 3 mounted on the first substrate 2, where the first substrate 2 is inclined so that a light emission direction of the LED 3 is different from an axial line C direction of the first observation hole 1a. The light irradiation device for inspection further comprises a second substrate 4 on which a resistance element 5 for limiting a current flowing through the LEDs 3 is mounted, where all or part of the second substrate 4 is separately arranged outside the first substrate 2 when viewed from the observation axial line C direction.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an inspection light irradiation device for irradiating an inspection object with LED light to inspect its surface, etc., and in particular to an inspection light irradiation device having an observation hole through which the inspection object can be inspected. [Background technology]

[0002] Known examples of this type of inspection light irradiation device include, as shown in Patent Document 1, a ring-shaped wiring board on which multiple LEDs are mounted, which is arranged around the observation hole that penetrates the thickness direction of the housing, and which focuses and irradiates the LED light onto the object to be inspected directly below the observation hole, or irradiates the LED light from around the object to be inspected.

[0003] More specifically, this wiring board is a partially annular flexible board that is rolled so that its ends are joined together to form a hollow truncated cone shape, with multiple LEDs mounted on the concave side. Furthermore, peripheral circuit elements such as current limiting resistors are also mounted on conventional wiring boards, and these elements are mounted on the LED mounting surface or the rear surface thereof.

[0004] However, when peripheral circuit elements are arranged on the LED mounting surface as in the former case, the thickness dimension of the light irradiation device becomes larger than necessary, which may result in a problem in that it is not possible to meet the requirement to bring the imaging device for inspection as close as possible to the object to be inspected, as in close proximity inspection. Let me explain why.

[0005] In this case, the peripheral circuit elements are arranged radially outside or inside the LED mounting area, because it may be difficult to arrange the peripheral circuit elements within the LED mounting area, i.e., between the LEDs, from the viewpoint of LED mounting density and interference with the LED light.

[0006] As a result, the radial width of the wiring board must be set to a certain degree, which inevitably increases the height of the truncated cone, i.e., the thickness of the light irradiation device.

[0007] However, because the imaging device is positioned on the opposite side of the inspection object from the inspection light irradiation device, the imaging device cannot be placed closer to the inspection object than the thickness dimension of the inspection light irradiation device. Therefore, if the thickness dimension of the inspection light irradiation device becomes too large, problems may arise in which it is unable to meet requirements such as close-range inspection. On the other hand, when peripheral circuit elements are arranged on the back side of the LED mounting surface as in the latter case, a problem can arise in that it becomes difficult to increase heat dissipation efficiency.

[0008] This is because the heat generated by the LEDs is dissipated from the housing by tightly adhering the back surface of the wiring board to the housing via, for example, a viscoelastic thermally conductive material, but the peripheral circuit elements protruding from the back surface of the board can reduce the adhesion of the thermally conductive material, resulting in reduced heat dissipation.

[0009] Furthermore, in both cases, the LEDs and peripheral circuit elements are mounted on the same wiring board, so in addition to the heat from the LEDs, the heat generated by the peripheral circuit elements is also added, and the amount of heat generated from a single wiring board tends to be excessive. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2006-179387 A Summary of the Invention [Problem to be solved by the invention]

[0011] However, the above-mentioned problems have traditionally been considered unavoidable in the field of inspection light irradiation devices in which the substrate is tilted in order to focus light on the object to be inspected or to irradiate light from the surrounding area, and this determines the upper limit of the LED luminous flux and the thickness of the device, with the upper limit being the heat dissipation performance determined by this.

[0012] The present invention was made possible only as a result of further in-depth investigation into problems that were previously accepted as common knowledge in this field, and aims to provide an inspection light irradiation device that is both significantly thinner and has improved heat dissipation properties. [Means for solving the problem]

[0013] That is, an inspection light irradiation device in one embodiment of the present invention comprises a housing having an inspection observation hole penetrating in the thickness direction, a first substrate arranged around the observation hole, and a plurality of LEDs mounted on the first substrate, wherein the first substrate is inclined so that the light emission direction of the LEDs is different from the axial direction of the first observation hole, and further comprises a second substrate on which a resistive element is mounted to limit the current flowing through the LEDs, and all or part of the second substrate is arranged separately outside the first substrate when viewed from the observation axial direction.

[0014] With this structure, since the resistive element is mounted on a second substrate that is separate from the first substrate, the first substrate only needs to have an area large enough to mount the LED, and its width dimension (the dimension in the direction along the slope) can be minimized, thereby making the thickness dimension caused by this slope, and ultimately the thickness dimension of the inspection light irradiation device, as small as possible, thereby achieving a thinner design than ever before. Therefore, it is possible to bring the imaging device, which is disposed on the opposite side of the inspection light emitting device from the inspection object in the thickness direction, as close as possible to the inspection object.

[0015] Furthermore, by mounting a resistive element (or other peripheral circuit elements other than the LED) on the second board and leaving the back surface of the first board flat with no elements mounted on it, the back surface of the first board can be brought into close contact with the housing over a wide area (either directly or via a viscoelastic thermal conductor), enabling efficient heat conduction and dissipation, thereby making it possible to increase the current supplied to the LED and increase its luminous flux.

[0016] Furthermore, by mounting the resistive elements (and other peripheral circuit elements other than LEDs) only on the surface of the second substrate, the back surface of the second substrate can be brought into close contact with the housing (either directly or via a viscoelastic thermal conductor, etc.), so that heat generated by the resistive elements, etc. can also be efficiently dissipated. Thus, the present invention was completed only by overturning the concept of a single substrate, which had been the common practice for this type of inspection light irradiation device. A more specific embodiment is one in which the first substrate is configured to gradually expand symmetrically around the observation axis in a cross section taken along the observation axis, and the LED is mounted on its inner surface.

[0017] In order to make it as compact as possible in the radial direction, it is preferable that the first substrate has a truncated hollow cone shape having a small opening and a large opening, the LED is mounted on its inner concave surface, and the second substrate is arranged closer to the small opening of the first substrate when viewed from a direction perpendicular to the observation axis.

[0018] A more specific embodiment is one in which the first substrate is a partially annular flexible substrate having ends joined or brought close to each other to form a truncated hollow cone shape, and the second substrate is a flat annular flexible substrate.

[0019] In order to hold the first and second boards in the housing without any difficulty, it is desirable that the housing be hollow and comprise a housing main body with an opening at one end and a cover body attached to the opening of the housing main body, and that a first board arrangement portion having a concave cone shape with the opposite LED mounting surface of the first board arranged to face the opening of the housing main body be provided, and that a second board arrangement portion having an annular groove shape in which the second board is arranged is provided around the first board arrangement portion.

[0020] In addition, a first substrate placement portion having a concave cone shape is provided within the opening of the housing body, with the opposite LED mounting surface of the first substrate being arranged to face the opening, and a second substrate placement portion on which the second substrate is placed is provided around the first substrate placement portion on the cover body. Effect of the Invention

[0021] According to the present invention thus configured, the inspection light irradiation device can be dramatically reduced in thickness and has improved heat dissipation properties. [Brief description of the drawings]

[0022] [Figure 1] 1 is an overall perspective view showing an inspection light irradiation device according to an embodiment of the present invention; [Diagram 2] 2 is a perspective view showing a state in which a cover body of the inspection light irradiation device in the embodiment is removed. FIG. [Diagram 3] FIG. 2 is an exploded perspective view of the inspection light irradiation device according to the embodiment. [Figure 4] 2 is a vertical cross-sectional view showing an internal structure of the inspection light irradiation device in the embodiment. FIG. [Diagram 5] 3 is an electrical circuit diagram of the inspection light irradiation device in the embodiment. FIG. [Figure 6] FIG. 13 is a schematic diagram showing an inspection light irradiation device according to another embodiment of the present invention. [Figure 7] FIG. 13 is a schematic diagram showing an inspection light irradiation device according to still another embodiment of the present invention. [Figure 8]FIG. 13 is a schematic diagram showing an inspection light irradiation device according to still another embodiment of the present invention. [Figure 9] FIG. 13 is a schematic diagram showing an inspection light irradiation device according to still another embodiment of the present invention. [Figure 10] FIG. 13 is a schematic diagram showing an inspection light irradiation device according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0024] As shown in Figures 1 to 4, the inspection light irradiation device 100 of this embodiment comprises a housing 1 having an inspection observation hole 1a penetrating in the thickness direction, a first substrate 2 having a truncated hollow cone shape held by the housing 1, and a plurality of light-emitting bodies, namely LEDs 3, mounted on the first substrate 2, and is configured so that an inspection object W, such as a product, which is positioned on the axis C of the observation hole 1a and irradiated with light from the LEDs 3 can be inspected through the observation hole 1a. Each part will be explained in detail.

[0025] The housing 1 includes a housing body 11 having, for example, a rectangular plate shape with one end surface open, and a thin plate-like cover body 12 that closes the opening of the housing body 11. The observation hole 1a is formed in the bottom plate portion of the housing body 11 that faces the opening. A first substrate placement section 1b having a concave conical surface is formed around the observation hole 1a so as to be coaxial with the observation hole 1a. The cover body 12 has the same contour as the housing 1 when viewed from the direction of the axis C of the observation hole 1a, and a light exit port 1c for emitting light from the LED 3 is provided at a position coaxial with the observation hole 1a.

[0026] The first substrate 2 is formed into the above-mentioned truncated hollow cone shape by joining or bringing the ends of a partially annular flexible substrate close to each other, and an LED mounting area is set on the concave surface. On the other hand, no LEDs 3 or other circuit elements are mounted on the back surface of the first substrate 2, which is the surface opposite the concave surface.

[0027] This first substrate 2 is clamped and held between the housing main body 11 and the cover body 12, and in this held state, the first substrate 2 is coaxial with the observation hole 1a and its back surface is in close contact with the first substrate placement section 1b of the housing 1. Also, as shown in Figures 3 and 4, the small-diameter opening 2a (the small opening in the claims) formed on the side of the first substrate 2 opposite the object to be inspected faces the observation hole 1a of the housing main body 11, and the large-diameter opening 2b (the large opening in the claims) formed on the object to be inspected is positioned so as to face the light emission outlet 1c of the cover body 12.

[0028] The LEDs 3 here are of a surface mount type, and multiple LEDs are arranged around the concave surface of the first substrate 2. However, since the first substrate 2 has a truncated hollow cone shape, the light emission directions of the LEDs 3 arranged on the concave surface converge to one point on the observation axis C. The type of LED is not limited to a surface mount type, and other types such as a bullet type may also be used. The light emission direction of the LEDs 3 refers to the direction perpendicular to the substrate surface at the location where the LEDs 3 are mounted.

[0029] With this configuration, the inspection light irradiation device 100 is configured to irradiate the inspection object W placed directly below the observation hole 1a with light from the LED 3 from around the oblique angle, and to enable the inspection object W to be observed and inspected through the observation hole 1a.

[0030] In this embodiment, a second substrate 4 on which peripheral circuit elements other than the LEDs 3 (for example, protective elements such as Zener diodes for protecting the LEDs 3 from surge voltages, etc.) including a resistive element 5 for limiting the current flowing through the LEDs 3 are mounted is provided separately from the first substrate 2. Note that an electric circuit diagram of this inspection light irradiation device 100 is shown in Fig. 5, and as is clear from Fig. 5, in this embodiment, only the resistive element 5 is used as a peripheral circuit element.

[0031] A more detailed description will be given below. As shown in Fig. 3 and Fig. 4, the second substrate 4 in this embodiment is a flat substrate in the shape of an annular belt whose inner diameter is larger than the outer diameter of the first substrate 2, and the peripheral circuit elements (resistance elements 5, not shown in Fig. 4) are mounted only on the surface thereof.

[0032] On the other hand, a second substrate placement portion 1d having a circular groove shape is provided on the bottom surface of the housing main body 11, outside the first substrate placement portion 1b, and the second substrate 4 is held in the housing 1 such that the back surface of the second substrate 4 is in close contact with the bottom surface of the second substrate placement portion 1d.

[0033] In this state, the second substrate 4 is positioned at a position offset from the center of the thickness of the first substrate 2 when viewed from the radial direction, specifically, within approximately the thickness of the first substrate 2 and closer to the small diameter opening 2a.

[0034] Furthermore, since the thickness of the second substrate 4 is smaller than the groove depth of the second substrate placement portion 1d, the second substrate 4 will move in the direction of the observation axis C inside the housing 1. To prevent this, as shown in FIG. 2, a number of rod-shaped rigid metal wires 6 having a predetermined rigidity are used for the electrical connection lines between the first substrate 2 and the second substrate 4, and the second substrate 4 is fixed to the housing 1 via the first substrate 2 by these rigid metal wires 6.

[0035] According to the inspection light irradiation device 100 described above, since the peripheral circuit elements such as the resistor element 5 are mounted on the second substrate 4 which is separate from the first substrate 2, the first substrate 2 only needs to have an area for mounting the LED 3, and the width dimension (dimension in the direction along the inclination) is minimized, so that the thickness dimension caused by the inclination, and therefore the thickness dimension of the inspection light irradiation device 100, can be made as small as possible, and a thinner shape than ever before can be realized. Furthermore, as a result, it is also possible to bring the imaging device 100, which is arranged on the opposite side of the inspection object W in the thickness direction across the inspection light irradiation device 100, as close as possible to the inspection object W.

[0036] In addition, peripheral circuit elements other than the LED 3, including the resistor element 5, are mounted on the second substrate 4, and no elements are mounted on the rear surface of the first substrate 2, so that the rear surface of the first substrate 2 can be reliably brought into close contact with the housing 1, and efficient heat conduction and heat dissipation can be achieved. This makes it possible to increase the current supplied to the LED 3 and increase its luminous flux.

[0037] The same is true for the second substrate 4, in which peripheral circuit elements such as resistive element 5 are mounted only on its front surface, so that the rear surface of the second substrate 4 can be securely attached to the housing 1, and heat generated by resistive element 5 etc. can also be efficiently dissipated. The present invention is not limited to the above-described embodiment.

[0038] For example, the first substrate 2 and the second substrate 4 may be arranged in a concentric pattern as shown in Figures 6 and 7. Also, as shown in Figure 8, the second substrate 4 may be inclined rather than flat.

[0039] Furthermore, the first substrate 2 and the second substrate 4 may be in the shape of a polygonal ring when viewed from the observation axis direction, or may be divided into multiple parts in the circumferential direction, as shown in Fig. 9. Also, the first substrate 2 and the second substrate 4 may not be in the shape of a ring, but may be in the shape of a partial ring.

[0040] Furthermore, the present invention is not limited to the ring-type inspection illumination device 100, but can also be applied to a line-type inspection illumination device 100 as shown in Fig. 10. In the figure, two rectangular band-shaped first substrates 2 are arranged symmetrically about the observation axis C in an inclined position so that the distance between them increases toward the inspection object W when viewed from the longitudinal direction (line direction C1). Here, among the band-shaped openings formed between the long sides of each first substrate 2, a narrow opening 2a formed between the long sides on the opposite side to the inspection object is continuous with an observation hole in a housing (not shown). Two second substrates 4 on which resistive elements 5 and the like are mounted are disposed separately on the outer sides of the first substrate 2. Here, similarly to the above embodiment, the second substrates 4 are disposed closer to the narrow opening when viewed from the line direction.

[0041] In the first embodiment, the entire second substrate 4 was located outside the first substrate 2, but as shown in Fig. 7, a part of the inside of the second substrate 4 may be configured to overlap with the first substrate 2 when viewed from the observation axis C. In this way, the second substrate 4 can be brought as close as possible to the observation axis C, and therefore the width dimension (radial dimension if annular) when viewed from the observation axis C can also be reduced.

[0042] Moreover, the first substrate placement portion or the second substrate placement portion may be provided on the cover body. Furthermore, the first and second substrates may be attached to the housing via, for example, a viscoelastic heat insulating material having high thermal conductivity. 6 to 10, the same reference numerals are used to denote parts and portions corresponding to those in the first embodiment, and the housing and resistive elements are not shown in these figures. In addition, the present invention can be modified in various ways without departing from the spirit of the invention, such as by combining parts of the above-described embodiments and modified examples. [Explanation of symbols]

[0043] 100: Inspection light irradiation device 1. Housing 11. Main body 12 Cover body 1a Observation hole 1b...First board placement section 1d...Second board arrangement section 2. First board 2a...Small diameter opening (small opening) 2b: Large diameter opening (large opening) 3 LED 4 Second board 5. Resistance element

Claims

1. A housing having an observation hole for inspection penetrating in a thickness direction, a first substrate arranged around the observation hole, and a plurality of LEDs mounted on the first substrate, the first substrate being inclined so that the light emission direction of the LEDs differs from the axial direction of the observation hole, A second substrate on which a resistor element for limiting a current flowing through the LED is mounted is further provided. The whole or a part of the second substrate is When viewed from the axial direction of the observation hole, the observation hole is disposed separately on the outer side of the first substrate, and An inspection light irradiation device characterized in that, when viewed from a direction perpendicular to the axis, it is located within a range of a thickness dimension of the LED mounting surface of the first board that is generated in the thickness direction due to tilt.

2. An inspection light irradiation device as described in claim 1, wherein, in a cross section taken along the axis of the observation hole, the first substrate is configured to gradually expand symmetrically around the axis of the observation hole, and the LED is mounted on its inner surface.

3. The first substrate has a hollow truncated cone shape having a small opening and a large opening, and the LED is mounted on a concave surface that is an inner surface of the first substrate, 3. The inspection light irradiation device according to claim 2, wherein the second substrate is disposed closer to the small opening of the first substrate when viewed from a direction perpendicular to the axis of the observation hole.

4. An inspection light irradiation device as described in any one of claims 1 to 3, wherein the first substrate is a partially annular flexible substrate having ends joined or brought close to each other to form a truncated hollow cone shape, and the second substrate is a flat annular substrate.

5. The housing is a hollow housing having a housing body with an opening at one end and a cover body attached to the opening of the housing body, An inspection light irradiation device as described in any one of claims 1 to 4, wherein a first substrate placement portion having a concave conical surface shape is provided within the opening of the housing body, and the first substrate is arranged so that the opposite LED mounting surface of the first substrate faces the opening, and a second substrate placement portion having an annular groove shape is provided around the first substrate placement portion in which the second substrate is arranged.

6. The housing is a hollow housing having a housing body with an opening at one end and a cover body attached to the opening of the housing body, A first board arrangement portion having a concave cone shape is provided within the opening of the housing body, and the first board is arranged so that the opposite LED mounting surface of the first board faces the first board.

5. The inspection light irradiation device according to claim 1, further comprising a second substrate placement portion on which the second substrate is placed, the second substrate being disposed in a portion of the cover body surrounding the first substrate placement portion.

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