JPH04408A - Lighting device and method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an illumination device and method used for inspecting the wiring pattern of a printed circuit board, or inspecting the presence or absence of components on a printed circuit board, and particularly relates to an illumination device and method used for inspecting the wiring pattern of a printed circuit board or the presence or absence of components on the board. The present invention relates to an illumination device and method for obtaining linear illumination light suitable for inspection.

(Prior Art) As an illumination device for obtaining linear illumination light, a slit light projection device (Japanese Patent Publication No. 17310) used in an inspection device for inspecting the presence or absence of components on a printed circuit board, or a printed circuit board A band-shaped light beam source (Japanese Unexamined Patent Application Publication No. 86682/1982) in the above pattern inspection apparatus is conventionally known.

(Problems to be Solved by the Invention) The above-mentioned slit light projection device uses a spherical lamp as a light source,
The light beam emitted from the light source is converted into slit light by a normal lens and a cylindrical lens (as there is no description in the detailed description of the invention in the above publication, it is inferred from the drawing (Figure 3)). However, there is a problem that the uniformity of the illumination light intensity within the irradiation area is insufficient, and reading errors are likely to occur during inspection.

Further, the band-shaped light beam source is composed of a laser, an expander that expands the laser beam, and a cylindrical lens, but there is a problem that even if the laser beam is expanded, the irradiation area is narrow.

The present invention has been made in view of the above points, and an object of the present invention is to provide an illumination device and method that has a wide irradiation area and makes the intensity of illumination light within the irradiation area more uniform.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an illumination device that illuminates with linear illumination light, which includes a first cylindrical lens and a lens located on the focal axis of the object space of the first cylindrical lens. A linear light source arranged in the image space, and a second cylindrical lens that focuses the illumination light from the first cylindrical lens on the focal axis of the image space are provided.

Further, it is preferable to provide a light equalizing means between the linear light source and the first cylindrical lens to equalize the illumination light intensity in a direction perpendicular to the optical axis.

The present invention also provides an illumination method for illuminating with linear illumination light, in which the illumination light is generated linearly, the generated illumination light is made into a luminous flux parallel to the optical axis, and the luminous flux is converged linearly. In an illumination method that uses linear illumination light, the illumination light is generated in a linear manner, and the intensity of the generated illumination light is made uniform in a direction perpendicular to the optical axis. The illumination light is a light beam parallel to the optical axis, and the light beam is focused into a line.

(Function) The linear light beam emitted from the linear light source is made into a light beam parallel to the optical axis by the first cylindrical lens, and the parallel light beam is focused on the focal axis of the image space by the second cylindrical lens. .

Furthermore, the intensity of the linear light beam emitted from the linear light source in the direction perpendicular to the optical axis is made uniform, and the linear light beam is incident on the first cylindrical lens.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a main part of an inspection apparatus including an illumination device according to an embodiment of the present invention, and FIG. 2 is a side view of the illumination device of FIG. 1. In these figures, 1 is a linear light source (for example, a halogen lamp), and first and second cylindrical lenses 3a and 3b are provided between this linear light source 1 and an object to be inspected (for example, a printed circuit board) 4. Furthermore, an integrator 2 is provided between the first cylindrical lens 3a and the linear light source 1.

The linear light source 1 is arranged on the focal axis of the object space of the first cylindrical lens 3a (the axis in the Y direction that is separated from the first cylindrical lens 3a by the focal length f and perpendicular to the optical axis 7), and The object 4 is arranged such that the area to be inspected on the object 4 to be inspected is located on the focal axis of the second cylindrical lens 3b. The integrator 2 moves an optical glass rod (for example, 0.5 to 1.0 mm in diameter) in a direction perpendicular to the optical axis 7.
A plurality of them are arranged continuously in the Y direction, and have the effect of making the intensity of the illumination light uniform in the Y direction.

FIG. 3 is a diagram for explaining the action of the integrator 2, in which the light beams ■ to ■' arriving from various directions are refracted by the action of the integrator 2 as an optical lens.
At the incident position of the first cylindrical lens 3a,
For example, as a result of being superimposed as shown as ■+■, ■'+■, and ■"+■', the intensity of the illumination light is made uniform in the Y direction.

The first cylindrical lens 3a is connected to the integrator 2
The incident light beam is made parallel to the optical axis 7 and is incident on the second cylindrical lens 3b, and the second cylindrical lens 3b focuses the incident light beam on the focal axis of the lens 3b. Therefore, before the inspection, the inspection area on the object 4 is irradiated with a uniform linear light flux in the longitudinal direction (Y direction in the figure), and the reflected light is transmitted through the objective lens 5 to the one-dimensional image sensor 6 ( For example, C0D).

As described above, according to this embodiment, by using a linear light source as the light source, the illumination light intensity can be made more uniform in the longitudinal direction over a wide range. As a result, the image sensor 6 can perform reading with a high S/N ratio. Furthermore, since the integrator 2 provides illumination light whose intensity is more uniform in the Y direction, inspection accuracy can be further improved.

Note that the arrangement of the optical glass rods of the integrator 2 is as follows:
The arrangement is not limited to the Y direction shown in the figure, but may be arranged in the Z direction in the figure.

Furthermore, the arrangement of the integrator 2 is not limited to between the linear light source 1 and the first cylindrical lens 3a as shown in FIG. 2, but between the first cylindrical lens 3a and the second cylindrical lens 3b. However, again,
It may be provided between the second cylindrical lens 3b and the object to be inspected 4.

Furthermore, the optical glass rod of the integrator 2 is not limited to a cylindrical one, but one with a concave lens cross section as shown in Fig. 4 may be used, or one with a semi-cylindrical shape may be used. You may.

Further, in FIG. 2, arcuate surfaces 3a' and 3b of the first cylindrical lens 3a and the second cylindrical lens 3b are shown.
' are arranged to face each other, but the flat surface 3
a' and 3b'' may be arranged to face each other.The point is that the first cylindrical lens 3a allows the light flux from the linear light source 1, which is incident from the first cylindrical lens 3a to the second cylindrical lens 3b, to become light. It is sufficient that the first cylindrical lens 3a and the second cylindrical lens 3a are parallel to the axis 7.
Each of the cylindrical lenses 3b may be a single lens or may be a compound lens.

(Effect of the invention) As detailed above, according to the lighting device or method of claim 1 or 3, the linear light beam emitted from the linear light source
Since the second cylindrical lens focuses the light onto the focal axis of the image space, by arranging the object to be inspected on the focal axis, a linear light beam with uniform intensity in the longitudinal direction can be obtained over a wide range. The reflected light of this linear light beam enables reading with a high S/N ratio, and the inspection accuracy of the inspection device can be improved.

According to the illumination device or method of claim 2 or 4, the light beam emitted from the linear light source is made more uniform by the light homogenizing means, so that inspection can be performed with even higher precision.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the main parts of an inspection device including an illumination device according to an embodiment of the present invention, and FIG. 2 is a side view of the illumination device of FIG. 1.
FIG. 3 is a diagram for explaining the function of the integrator, and FIG. 4 is a diagram showing another embodiment of the integrator. DESCRIPTION OF SYMBOLS 1... Linear light source, 2... Integrator (light uniformization means), 3a... First cylindrical lens, 3b
...Second cylindrical lens. v32 diagram

Claims (1)

[Claims] 1. In a lighting device that illuminates with linear illumination light,
a first cylindrical lens, a linear light source arranged on the focal axis of the object space of the first cylindrical lens, and a second cylindrical lens that focuses the illumination light from the first cylindrical lens on the focal axis of the image space. A lighting device characterized by being provided with a cylindrical lens. 2. A light equalizing means for equalizing illumination light intensity in a direction perpendicular to the optical axis is provided between the linear light source and the first cylindrical lens. lighting equipment. 3. In an illumination method that uses linear illumination light,
An illumination method characterized by generating illumination light in a linear form, converting the generated illumination light into a luminous flux parallel to an optical axis, and converging the luminous flux into a linear shape. 4. In an illumination method that uses linear illumination light,
The illumination light is generated in a line, the intensity of the generated illumination light is made uniform in the direction perpendicular to the optical axis, the uniform illumination light is made into a light beam parallel to the optical axis, and the light beam is made into a line. A lighting method characterized by focusing in a shape.