Coaxial lighting device for telecentric lens

Abstract

To provide a coaxial lighting device for a telecentric lens that has a cylindrical part capable of being inserting into a telecentric lens, and can emit brighter light from an apical surface of the cylindrical part.SOLUTION: A coaxial lighting device 1 for a telecentric lens comprises: a housing 2 having a cylindrical part 21 extending in an axial direction and capable of emitting light from a tip 21aa of a hollow part 21a; a light-emitting part 3 provided in the housing 2; and a lens part 4 that is provided in the housing 2, composed of one or more convex lenses 41, 42, receives light from the light-emitting part 3, has an image point B located at a position from an axial center Aa of the hollow part 21a of the cylindrical part 21 to the tip 21aa or at an outside position near the tip 21aa, and emits light toward the image point B.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a coaxial illumination device for a telecentric lens that is inserted into a telecentric lens and used as coaxial epi-illumination. [Background technology]

[0002] Conventionally, telecentric lenses with coaxial epi-illumination have often been used to inspect items (products) produced in factories (visual inspection for defects, scratches, dirt, foreign matter, etc.) Telecentric lenses with coaxial epi-illumination use a coaxial illumination device inserted into the telecentric lens.

[0003] As shown in Patent Documents 1 and 2, for example, a coaxial lighting device generally includes a light-emitting unit, a lens unit (a collimating lens and a condensing lens in Patent Document 1, and a lens mechanism (first and second lenses) in Patent Document 2), and a light-guiding unit (the light-guiding unit in Patent Document 1 and the glass rod in Patent Document 2) in a housing. The light-emitting unit typically has one light-emitting diode that emits light. The lens unit receives light from the light-emitting unit and radiates it toward the light-guiding unit. The light-guiding unit receives light from the lens unit and guides it toward the outside (by guiding it while reflecting it off the side surfaces) to radiate it. The housing surrounds the light-guiding unit, and this cylindrical unit can be inserted laterally into a telecentric lens. For example, Patent Document 3 describes that a cylindrical unit (a part of the case (housing) surrounding an optical guide body in Patent Document 3) of a coaxial lighting device (an inspection lighting device in Patent Document 3) is inserted laterally into a telecentric lens (an inspection device in Patent Document 3) (see FIG. 1(A) in Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-045192 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-111377 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-246952 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the light guide sections described in Patent Documents 1, 2 and 3 are made of glass or synthetic resin, and the brightness of the light emitted from the coaxial lighting device is reduced accordingly.

[0006] The present invention has been made in view of the above circumstances, and its object is to provide a coaxial illumination device for a telecentric lens that has a cylindrical portion that can be inserted into a telecentric lens and is capable of emitting brighter light from its tip end face. [Means for solving the problem]

[0007] In order to achieve the above object, the coaxial lighting device for a telecentric lens described in claim 1 comprises: a housing having a cylindrical portion that extends in an axial direction and is capable of emitting light from a tip of a hollow portion; a light emitting portion provided within the housing; and a lens portion that is provided within the housing and is composed of one or more convex lenses, receives light from the light emitting portion, has an image point located at a position from the center of the axial direction of the hollow portion of the cylindrical portion to the tip or at a position outside near the tip, and radiates light toward the image point.

[0008] A coaxial lighting device for a telecentric lens according to a second aspect of the present invention is the coaxial lighting device for a telecentric lens according to the first aspect, wherein the axial position of the light emitting portion relative to the lens portion is variable. [Effects of the Invention]

[0009] The coaxial illumination device for a telecentric lens of the present invention has a cylindrical portion that can be inserted into a telecentric lens, and can emit brighter light from its tip end surface. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a left side view showing a coaxial illumination device for a telecentric lens according to an embodiment of the present invention. FIG. [Figure 2] 1. FIG. 3 is a cross-sectional view showing the coaxial illumination device for a telecentric lens (a cross-sectional view taken along the line CC in FIG. 1). [Figure 3] This is a cross-sectional view of Figure 2 with the state of light added. [Figure 4] FIG. 2 is a front view of the coaxial illumination device for a telecentric lens inserted into the telecentric lens. [Figure 5] This is a front view of Figure 4 with the light state added. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described. A coaxial lighting device 1 for a telecentric lens according to an embodiment of the present invention can be inserted into a telecentric lens 6, as will be described later. As shown in FIGS. 1 and 2, the coaxial lighting device 1 for a telecentric lens includes a housing 2, a light-emitting unit 3, and a lens unit 4. The coaxial lighting device 1 for a telecentric lens also includes a control cable 5, the connector 5a of which can be connected to a dimmer or the like (not shown). Because the control cable 5 is long, its intermediate portion is omitted in FIG. 2 and FIG. 3, which will be described later, and the portion from its intermediate portion to the connector 5a is omitted in FIGS. 4 and 5, which will be described later.

[0012] The housing 2 is formed with a cylindrical portion 21. The cylindrical portion 21 has an outer diameter that allows it to be inserted into the telecentric lens 6 (see FIG. 4). The cylindrical portion 21 extends in the axial direction (the direction of the central axis A of the coaxial illumination device 1 for a telecentric lens) and has a hollow portion 21a. The hollow portion 21a can emit light (indicated by a solid line with an arrow in FIG. 3) from its tip 21aa.

[0013] The hollow portion 21a of the cylindrical portion 21 is smaller in size in the radial direction (direction perpendicular to the axial direction) than the lens portion 4. The housing 2 has an inner wall shape that maintains physical strength while not blocking light traveling from the lens portion 4 to the hollow portion 21a of the cylindrical portion 21 (see FIG. 3). The inner walls of the housing 2 (including the inner walls of the hollow portion 21a) are black and / or matte to prevent reflection even if light hits them. The exterior shape of the housing 2 can be generally axisymmetric (see FIG. 1) or approximately axisymmetric. The housing 2 can be provided with heat dissipation fins 22 on the outer wall side depending on the heat generation amount of the light-emitting unit 3. The housing 2 can also be provided with a rear housing portion 23 that seals the rear side and to which the light-emitting unit 3 is fixed. The rear housing portion 23 is usually separate from the rest of the housing 2 and can be fitted and fixed with screws or the like. The housing 2 is made of a metal material such as aluminum or copper, or a resin material.

[0014] The light-emitting unit 3 is provided in the housing 2. The light-emitting unit 3 normally has one light-emitting diode 31 that emits light and is provided on the central axis A. In some cases, it may have multiple light-emitting diodes. The light-emitting diode 31 is mounted on a wiring board 32, and can be supplied with and controlled by the above-mentioned dimming device or the like via wiring (not shown) between the wiring board 32 and the control cable 5 and the control cable 5.

[0015] The light emitting unit 3 emits light toward the lens unit 4 at a predetermined directivity angle.

[0016] The lens unit 4 is provided inside the housing 2. The lens unit 4 is made up of one or more (two in FIG. 2) convex lenses 41 and 42. The convex lenses may be biconvex lenses, plano-convex lenses, or convex meniscus lenses.

[0017] 3, the lens unit 4 receives light from the light emitting unit 3. The lens unit 4 has a radial size large enough to receive light emitted by the light emitting unit 3 at least within a predetermined directivity angle.

[0018] The lens unit 4 has an image point B located from the axial center Aa of the hollow portion 21a of the cylindrical portion 21 of the housing 2 (where L is the length of the hollow portion 21a, and the point is halfway from both ends of L) to the tip 21aa. The lens unit 4 emits light toward the image point B. The light emitted from the lens unit 4 travels straight through the air to reach the image point B. The light that passes through the image point B spreads and is emitted to the outside from the tip 21aa. Here, since the image point B is located from the axial center Aa of the hollow portion 21a to the tip, all or almost all of the light that passes through the image point B is emitted to the outside from the tip 21aa. The light that is emitted to the outside becomes a spot light with a narrowed radial range. Note that, if the components of the telecentric lens 6 do not interfere with the light's propagation, it is also possible to have the image point B located outside near the tip 21aa (outside the coaxial illumination device 1 for telecentric lenses). Furthermore, when a taper is formed from the end of the hollow portion 21a (see FIG. 2, etc.), the axial center Aa is the center of the portion that does not include the taper.

[0019] As described above, the coaxial lighting device 1 for a telecentric lens has a cylindrical portion 21 that can be inserted into the telecentric lens 6 and can emit bright light from its tip surface (specifically, the tip 21aa of the hollow portion 21a). The coaxial lighting device 1 for a telecentric lens can emit brighter light because it does not pass through a glass or synthetic resin light guide, as described in the Background Art section. Furthermore, the light emitted from the tip surface of the cylindrical portion 21 is refracted by one or more convex lenses 41, 42, and is not mixed with light reflected by any other components. Therefore, uniformity (such as radial uniformity) is not impaired by reflected light. Furthermore, the radial size of the refracted light by one or more convex lenses 41, 42 is easily controlled, which allows the range of light that passes through an aperture 62 (described later) of the telecentric lens 6 and strikes the beam splitter 63 to be widened and easily controlled.

[0020] Such a coaxial illumination device 1 for a telecentric lens can be inserted into a telecentric lens 6, as shown in FIG. 4. More specifically, the cylindrical portion 21 of the coaxial illumination device 1 for a telecentric lens can be inserted into an illumination device insertion portion 61 provided on the side of the telecentric lens 6. Inside the telecentric lens 6, an aperture 62 and a beam splitter 63 are provided in front of the cylindrical portion 21 of the inserted coaxial illumination device 1 for a telecentric lens. As shown in FIG. 5, in the telecentric lens 6, light emitted from the coaxial illumination device 1 for a telecentric lens (indicated by a solid line with an arrow in FIG. 5) passes through the aperture 62 and is reflected by the beam splitter 63. The light then passes through an objective lens 64 provided on the central axis D of the telecentric lens 6, illuminating an object (not shown) placed below it (coaxial epi-illumination). A camera 7 can be attached to the top of the telecentric lens 6.

[0021] The above describes a coaxial illumination device for a telecentric lens according to an embodiment of the present invention. However, the present invention is not limited to the above embodiment and various design modifications are possible within the scope of the claims. For example, the axial position of the light-emitting unit 3 relative to the lens unit 4 can be made variable. To achieve this, for example, the rear housing unit 23 can be moved axially within a predetermined range and fixed to another part of the housing 2 with screws or the like. This makes it possible to easily adjust the position of the image point B to match the specifications of the telecentric lens 6 and adjust the range of light that strikes the beam splitter 63. For example, moving the light-emitting unit 3 axially farther from the lens unit 4 moves the image point B farther from the beam splitter 63, thereby widening the range of light that strikes the beam splitter 63.

[0022] 1 Coaxial illumination device for telecentric lenses 2. Case 21 Cylindrical part 21a Hollow part 21aa Tip of hollow part 22 Heat dissipation fin 23 Rear of the housing 3 Light-emitting part 31 Light-emitting diode 32 Wiring board 4 Lens section 41, 42 Convex lenses 5 control cables 5a connector 6 Telecentric Lenses 61 Illumination device insertion section 62 aperture 63 Beam Splitter 64 objective lenses 7. Camera A Central axis of the coaxial illumination device for telecentric lenses Aa Axial center of hollow section B Image point D Central axis of telecentric lens

Claims

1. a housing having a cylindrical portion extending in an axial direction and capable of emitting light from a tip of a hollow portion; a light emitting unit provided in the housing; a lens unit provided in the housing, comprising one or more convex lenses, receiving light from the light emitting unit, having an image point at a position from the center of the axial direction of the hollow portion of the cylindrical portion to the tip or at an outer position near the tip, and emitting light toward the image point; A coaxial illumination device for a telecentric lens comprising:

2. 2. The coaxial illumination device for a telecentric lens according to claim 1, A coaxial illumination device for a telecentric lens, wherein the axial position of the light emitting portion relative to the lens portion is variable.

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