JP2966729B2 - Light guide element and method of using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide element and a method for using the same.

[0002]

2. Description of the Related Art When inspecting a product, it may be necessary to observe and inspect the side surface of the product to be inspected. When the product to be inspected has a “flat” shape, the side surface to be observed is naturally a flat portion.

When observing the flat side surface of such a flat object to be inspected, if the image forming optical system is optically arranged in a plane corresponding to the observation portion of the object to be inspected, the image forming optical system becomes There is a problem that the inspection device takes up a large area and the inspection apparatus is two-dimensionally enlarged.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a light guide element suitable for observing a relatively flat observation object and a method of using the same. .

[0005]

The light guide element of the present invention comprises a "rectangular transparent parallel flat plate" and a "reflective surface".
And a "polishing surface" and a "light diffusing surface" (claim 1).

The "reflection surface" forms a slit-shaped slope formed so as to be inclined in the width direction at one end of a transparent rectangular parallel plate, that is, one side of the rectangle. It has been subjected to a reflective surface treatment. The longitudinal direction of the slit-shaped slope is the longitudinal direction of the side where the slope is formed.

The direction in which the slit-shaped slope is inclined is the width direction of the slit, that is, the direction of the length of the slope orthogonal to the length direction of the slit.

The "polishing surface" is formed in a slit shape as a "light incident portion" at the side edge of the parallel plate that intersects the slope formed on the reflection surface.

That is, the slit-shaped inclined surface and the slit-shaped polished surface have length directions parallel to each other, and
By inclining each other, a “wedge-shaped cross-sectional shape” is formed (as viewed from the length direction of each slit).

The "light diffusing surface" is formed on at least one of the parallel flat surfaces excluding the reflection surface and the polished surface.

[0011] The light incident portion of the "light guide element" according to claim 1 is directed to the "object to be observed", and the "illumination light source" provided on the side opposite to the object to be observed with respect to the light guide element is turned on. The light from the illumination light source is illuminated by the light diffusing surface of the light guide element as “diffusive illumination light” onto the object to be observed, and the light from the object to be observed is taken into the light guide element from the light incident portion and the reflection surface The light guide element can be used so that the light is reflected by the light guide element and guided inside the light guide element, thereby leading to the "imaging optical system" (claim 2).

Alternatively, a pair of the light guide elements according to claim 1 are provided so that respective “light incident portions” face each other, and an “object to be observed” is set between the light incident portions facing each other. Then, the "illumination light source" arranged on the side opposite to the light incident portion of each light guide element is turned on, and light from each illumination light source is "diffused illumination light" by the light diffusing surface of each light guide element. Illuminating the observation target object, taking in the light from the observation target object from each light incidence part, reflecting the light from each reflection surface, and guiding the inside of each light guide element, `` imaging optics corresponding to each light guide element (Claim 3).

[0013]

As described above, light from the object to be observed is taken into the light guide element from the polished surface, which is the "light incident portion" of the light guide element, and is reflected by the reflection surface to bend the optical path. The light is guided through the light guide element and is emitted toward the imaging optical system.

Further, the object to be observed is illuminated with illumination light which is made diffusive by the light diffusing surface of the light guide element.

[0015]

EXAMPLES Specific examples will be described below.

FIG. 1 shows one embodiment of the light guide element according to claim 1.
An example is shown.

The light guide element 1 has a reflective film formed on one end of a “parallel rectangular flat plate” made of a transparent material such as glass, quartz, or plastic, and a slit-shaped inclined surface 11 formed to be inclined in the width direction. 11A is formed, and the inclined surface 11 is used as a reflection surface.

The “parallel plate side edge” intersecting with the slope 11 is
As a light incident portion, the slit-shaped polishing surface 12A is polished, and one flat portion of the parallel flat surface excluding the reflection surface and the polishing surface 12A is a light diffusion surface 12B. In this embodiment, the polishing surface 12A and the light diffusing surface 12B are a part of the same surface 12.

The angle formed by the slope 11 and the polishing surface 12A is:
In this example, it is 45 degrees.

In this embodiment, the surface 15 parallel to the light-diffusing surface 12B is a smooth light-transmitting surface. A diffusion surface may be formed, and the light diffusion surface 12B in the figure may be a smooth light transmission surface.

In this embodiment, the surfaces 13 and 14 corresponding to the side surfaces of the light guide element 1 are painted black so as to be light-shielding.

The bottom surface 16 of the light guide element 1 is, of course, a light-transmitting flat surface.

FIG. 2 is a view showing one embodiment of the second aspect of the present invention. One of the methods of using the light guide element shown in FIG.
An example is shown. This embodiment is a method of observing a side portion of an observation object 0 that is flat up and down.
Is set on a support table 3 placed on a stage 2 as shown in the figure.

On the right side of the stage 2, a light guide element 1
Are deployed as shown in the figure. That is, the light guide element 1
Is the surface of the polishing surface 12A and the light diffusing surface 12B
It is arranged so that the height of the polished surface 12A is substantially the same as the side surface of the set observation object 0 toward the side.

An imaging optical system 5 is provided below the bottom surface portion 16 of the light guide element 1, and an area sensor 6 is provided so that the image plane matches the imaging plane. Imaging optical system 5
The area sensor 6 and the area sensor 6 are integrated to be displaced in the optical axis direction of the imaging optical system 5 to “focus”.
May be performed.

With respect to the light guide element 1, the side opposite to the side on which the observation object 0 is set is referred to as an “illumination light source” and LE
D4 is deployed.

With the observation object 0 set, the LED 4
Is emitted, the emitted light enters from the smooth light transmitting surface 15 of the light guide element 1 and is diffused by the light diffusing surface 12B, and the right side surface of the observation object 0 is diffused as illumination light. Illuminate evenly.

Light reflected from the observation object 1 is transmitted from the polished surface 12A, which is a light incident portion of the light guide element 1, to the light guide element 1.
1 that is incident on the inside and becomes a reflection surface by the reflection film 11A
The light is reflected by the light guide element 1, is guided downward in FIG. 2 in the light guide element 1, enters the imaging optical system 5 when emitted from the bottom surface 16, and is incident on the area sensor 6 by the action of the imaging optical system 5. Form an image.

By the output of the area sensor 6, it is possible to observe the situation on the right side of the observation object 0.

For focusing, refer to “Image forming optical system 5”.
The area sensor 6 and the area sensor 6 may be integrated, and may be focused by displacing the imaging optical system 5 in the optical axis direction. However, the light guide element 1, the imaging optical system 5, and the area sensor 6 may be integrated, and these may be displaced in the left-right direction in FIG. 2 to perform focusing.

Alternatively, the light guide element 1 and the imaging optical system 5
And the area sensor 6 are integrated to make them immovable,
The position of the observation target 0 may be adjusted on the stage so that the observation site of the observation target 0 is located at the object plane position conjugate to the area sensor 7.

FIG. 3 shows an embodiment of the third aspect of the present invention, showing an example of a method of using a pair of light guide elements 1A and 1B.

The pair of light guide elements 1A and 1B are arranged so that their light incident portions face each other, and the observation object 0A is set between the opposing "light incident portions".

On the side of each light guide element 1A, 1B opposite to the light incident portion, LEDs 4A, 4B, which are "illumination light sources", are provided. Below each light guide element 1A, 1B, a connection is made. Image optical systems 5A and 5B are provided, and area sensors 6A and 6B are provided so that the light receiving surfaces thereof match the image surfaces of these image forming optical systems 5A and 5B.

Since the pair of light guide elements 1A and 1B are the same, the light guide element 1A will be described with reference to FIG. 1 except for one point. This is the same as the light guide element 1 described above.

The light guide element 1A is different from the light guide element 1B in that the polished surface 12a, which is a light incident portion, is an "inclined surface".
It is a point formed in. That is, the polishing surface 12a has a slight "tilt angle" so as to be inclined toward the slope 11 '.

"The side edge of the parallel plate that intersects the slope is polished to the slit-shaped polishing surface as a light incident portion" means that the polishing surface itself is formed as an inclined surface as in this case. It also includes. As described above, since the light guide elements 1A and 1B are the same, each part is given the same reference numeral.

The object to be observed 0A is a surface-mount type IC package (SOP: Small Outline Package), and the purpose of observation is to “lead (lead pin)” of the lead pins in the lead pin arrays LP1 and LP2 formed on both sides of the package. The free end of the lead pin is raised from the original arrangement surface of the free end of the lead pin) and whether or not the arrangement pitch of the lead pin is "disordered".

The observation object 0A is transported on the inspection line in the same direction. When the observation object 0A reaches a predetermined position on the inspection line, the suction-type holding unit 100 provided at the tip of the arm robot to be program-controlled.
And in the state of "suspended" as shown in the figure,
It is set at a predetermined position (an intermediate portion between the light guide elements 1A and 1B).

When the LEDs 4A and 4B emit light in this state, light is emitted from the light diffusing surface 12b of the light guide elements 1A and 1B.
Illuminates the observation object 0A obliquely from below.

It should be noted here that the LED 4A is
The left lead pin LP in FIG. 3 of the observation object 0A
The LED 4B is an illumination unit for imaging the right lead pin LP1 portion.

The lead pins are made of metal, the surface of which usually has a high reflectivity on a bare metal surface. Therefore, if the lead pin portion is directly illuminated with the illumination light beam, the resolution of the captured image of the lead pin portion may deteriorate due to halation due to reflection.

As in the embodiment being described, for example, the lead pin L on the right side of the observation object 0A by the LED 4B in FIG.
When the part P1 is illuminated, the lead pin LP1 on the right side
When viewed from the side of the area sensor 6A, the light is illuminated by so-called “backlight”. Therefore, the lead pin LP1 emerges as “clear” as a silhouette image against the back light that is diffused light. This makes it possible to capture clear images.

The same applies to the image pickup of the lead pin LP2 picked up by the area sensor 6B.

The light from the lead pins LP1 and LP2 is
Each of the light guide elements 1A, 1B is taken into the light guide element from the polished surface 12a, reflected by the reflection surface 11 ', emitted from the bottom surface 16a, and formed into the imaging optical system 5A, 5A.
B, and forms an image on the light receiving surfaces of the area sensors 6A and 6B.

As described above, the illumination light from the LEDs 4A and 4B becomes diffused light, and the lead pins LP intended for illumination are used.
2. Illuminate the LP1 portion so as to "go diagonally downward from diagonally upward".

In such a case, in order to effectively capture the imaging light from the polished surface 12a, the polished surface 12a is formed as an inclined surface, and the incident light enters the reflecting surface 11 'by refraction by the polished surface 12a. So that the angle approaches 45 degrees,
Effective capturing of imaging light is achieved.

The outputs of the area sensors 6A and 6B are sent to an image processing device (not shown), and are used for inspection of "floating" of the lead pins in each lead pin row and "disorder" of the arrangement pitch.

FIG. 4A shows the output of the area sensor 6A,
(B) shows a state in which the output of the area sensor 6B is displayed on the monitor display, (a) shows an example in which the lead pin LP1 part is displayed, and (b) shows an example in which the lead pin LP2 part is displayed. The presence or absence of “floating” of the lead pins and “disorder” of the arrangement pitch can be reliably detected.

After the inspection, it is preferable that the arm robot returns the defective product to the collecting section and the non-defective product to the assembly line.

In the embodiment shown in FIG. 3, focusing can be performed in the same manner as in the embodiment shown in FIG.

[0052]

As described above, according to the present invention, a novel light guide element and a method for using the same can be provided.

As described above, the light guide member of the present invention comprises:
Since the optical path of the imaging light flux taken in from the light incident part is bent in the guide, the arrangement of the observation optical system such as the imaging optical system is three.
It can be made dimensional, and the arrangement of the optical system can be made compact.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a light guide element of the present invention.

FIG. 2 is a diagram for explaining one embodiment of the invention described in claim 2;

FIG. 3 is a view for explaining one embodiment of the invention described in claim 3;

FIG. 4 is a diagram showing an example of a state in which the state of each observation unit of an observation target imaged in the embodiment of FIG. 3 is displayed on a monitor display.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light guide element 11 Slope 11A Reflective film 12A Polished surface 12B Light diffusion surface

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Claims (3)

(57) [Claims] 1. A reflecting surface is formed on one end of a rectangular transparent parallel plate having a slit-like slope formed so as to be inclined in the width direction. As a part,
A light guide element polished to a slit-shaped polishing surface, wherein at least one of the parallel flat surfaces excluding the reflection surface and the polishing surface is a light diffusion surface. 2. The light guide element according to claim 1, wherein a light incident portion of the light guide element is directed toward an observation object, and an illumination light source disposed on a side opposite to the observation object with respect to the light guide element is turned on. Illuminates the observation target object as diffusive illumination light by the light diffusion surface of the light guide element, takes in the light from the observation target object from the light incident portion, reflects the light from the reflection surface, and reflects the light from the reflection surface. A method for using a light guide element, wherein the light guide element is guided inside an element and guided to an imaging optical system. 3. A light guide element according to claim 1, wherein a pair of light incident portions are provided so as to face each other, and an object to be observed is set between the light incident portions facing each other. The illumination light source provided on the side opposite to the light incident portion of the guide element is turned on, and the light from each of the above illumination light sources is illuminated by the light diffusing surface of each light guide element as diffusive illumination light to illuminate the observation target. Then, the light from the observation object is taken in from each of the light incident portions, reflected by each of the reflection surfaces, and guided inside each of the light guide elements, to an imaging optical system corresponding to each of the light guide elements. Use of a light guide element characterized in that it is guided.