JPS6097312A - Illuminating device by falling light - Google Patents

Abstract

PURPOSE:To enable uniform illumination with falling light at the minimized loss of quantity of light by irradiating the light past a fiber via a ring type convex lens to the inside surface of a diffusion plate having approximately a spherical shape and illuminating an object to be inspected with the falling reflected light thereof. CONSTITUTION:A diffusion plate 2 is made into an approximately semispherical shape and a hole 7 for observation with a television camera 6 is opened at the center thereof. When light is illuminated from a light source 3 via a fiber 5 to a ring type lens 4, a spot 8 having an elliptical ring shape and having spread is obtd. from the transmitted light. If the spot light 8 is irradiated to the inside surface of the plate 2 with the center as a reference, the spot light is diffused by the plate 2 and is irradiated to an object 1 to be inspected. The object 1 which is set perpendicularly downward direction eventually uniformly illuminated from the entire upper diagonal direction. Then the diffused light is irradiated to fall onto directly the object 1 and therefore there is no loss of the quantity of light.

Description

[Detailed Description of the Invention] [Technical Field] The present invention uses epi-illumination that can uniformly illuminate the entire object without being affected by the unevenness of the object in order to perform an external appearance inspection of the object with a television camera. Regarding lighting devices.

[Background technology]

A method of illuminating light from the receiving direction of a television camera is epi-illumination using a ring-shaped light source, and a method of irradiating transmitted light using a milky-white translucent plate as a diffuser. There are circular wall lights and optical fibers bundled in a ring, but the former has the disadvantage that it is difficult to control the light, and the latter is expensive. Since it is necessary to use a type diffuser plate, there is a problem that Gwangju loss is large.

[Purpose of the invention]

This invention aims to provide a uniform epi-illumination device in which the optical loss is minimized.

[Disclosure of the invention]

Figure 1 shows that the object to be inspected (1) is inspected with a television camera (6), so a light source (6) is installed with a diffuser plate (2) placed in the middle of the camera.
The light is guided through the fiber (5) through a ring-shaped convex lens (4).
) shows a state in which light is applied to the diffuser plate (2) and the reflected light illuminates the object to be inspected.

Figure 2 shows the structure of the fiber (5) and ring-shaped convex lens (4). In the figure, a and b indicate distance, and the relationship satisfies the following equation.

11 i soil and stone=■ Here, f does not indicate the focal length of the ring-shaped convex lens (4).

λ is from the exit of the fiber (5) to the ring lens (4)
(b) shows the condensing distance of the light that exits the fiber (5), enters the ring-shaped lens (4), and is further condensed. The relationship between the diffuser plate (2), the ring-shaped convex lens (4), and the exit of the fiber (5) must satisfy the above formula.

FIG. 6 shows the distribution of spot light on the diffuser plate (2) as seen from the top surface of the diffuser plate (2). Ring-shaped convex lens (
4) has an elliptical shape in order to irradiate light obliquely to the diffuser plate (2).

A matte white coating with high reflectance is applied to the inner surface (on the inspection object (1) side) of the diffuser plate (6).

The diffuser plate (2) has a substantially hemispherical shape, and the reflected light is focused on the object to be inspected (1). There is also a hole in the center so that it can be observed with a television camera (6).

Light guided by an optical fiber (5) from a light source (5) is output from the tip of the fiber (5) and illuminates a ring-shaped convex lens (4) located at a certain distance in front as shown in FIG.

As shown in Fig. 2, the ring-shaped convex lens (4) is formed from the locus of the convex lens on the focal side Rif rotated once around a point on the outer circumference, and the lens on the focal side Ml f on the entire circumference. It is like a series of
The center of the lens is curved with a curvature corresponding to the focal length f.

Optical fiber (
5) and a ring-shaped convex lens (4) arranged corresponding to the My fiber (5), a ring-shaped spot light is formed and illuminates the central muscle of the diffuser plate (2).

By illuminating the ring-shaped lens (4) with light from the fiber (5), the transmitted light becomes a spread ring-shaped spot light (8). i.e. fiber (5)
By irradiating the inner surface of the diffuser plate (2) from the object to be inspected (1) with a ring-shaped lens (4) with the center reference, a spot light (8) consisting of an elliptical ring-shaped pattern shown in FIG.
) can be obtained. Spora I light (8) irradiated onto the diffuser plate (2) in a ring shape (ellipse) is diffused by the diffuser plate (2) and irradiated onto the object to be inspected (1). The light is then scattered by the inner surface of the diffuser plate (2) and epi-illuminated onto the object to be inspected (1), which is set vertically downward, and the direction of the light as seen from the object to be inspected (1) is diagonally upward. It is uniformly illuminated from all directions.

〔Effect of the invention〕

As described above, according to the present invention, since light is guided through a fiber, a light source whose light value can be controlled can be used, and the fibers used do not need to be bundled into a ring shape as in the past, so they can be manufactured at low cost. Moreover, since the diffused light is reflected directly onto the object to be inspected, there is no loss of light quantity.

[Brief explanation of the drawing]

1 to 5 are views showing one embodiment of the present invention, in which FIG. 1 is a schematic side view, FIG. 2 is a schematic side view of the main part, and FIG. 6 is a schematic diagram. Patent applicant Matsushita Electric Works Co., Ltd. Representative Patent Attorney η Toshimaru Moto (and 2 others) Figure 1 Figure 2-~, 3fl

Claims (1)

[Claims] (1) An epi-illumination device characterized by irradiating light guided by a fiber to the inner surface of a substantially spherical diffuser plate in a centered manner through a ring-shaped convex lens, and epi-illuminating an object to be inspected with the reflected light.