JPH031194Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a visual sensor illumination device suitable for application to, for example, industrial intelligent robots.

(Prior art) As an example of this type of lighting device,
There is a device described in Publication No. 50322. this is,
As shown in FIG. 6, after the light from the light source 1 is focused by the condensing lens 2, the first half mirror 6a
The reflected light is divided into two by the reflected light and the transmitted light, and the reflected light irradiates the workpiece 3, which is the subject, from an oblique direction.The transmitted light is further divided into two by the second half mirror 6b, and the reflected light The workpiece 3 is illuminated from the vertical direction. The reflected light from the workpiece 3 passes through the second half mirror 6b and enters the camera 4, which is an imaging device, where visual recognition is performed. This device can switch between illumination of the workpiece 3 from both diagonal and vertical directions and illumination from a single direction, so it has the advantage of being able to expand its uses as a lighting device. .

(Problems to be solved by the invention) However, in the above-mentioned conventional apparatus, when performing simultaneous illumination in an oblique direction and a vertical direction, the light from the light source 1 passes through the two half mirrors 6a and 6b. There is a problem that both the amount of illumination light and the amount of light incident on the camera 4 decrease. For example, the amount of light from light source 1 is L
Roughly speaking, in the oblique illumination section, the reflected light reduced to 1/2L by the first half mirror 6a illuminates the workpiece 3, and the reflected light from the workpiece 3 is as follows.
Since the light passes through the second half mirror 6b and enters the camera 4, the amount of light reaching the camera 4 becomes 1/4L.
In one vertical illumination section, the transmitted light reduced to 1/2L by the first half mirror 6b is transmitted to the second half mirror 6b.
The light reflected from the workpiece 3 is further divided into two parts by the second half mirror 6b to illuminate the workpiece 3 with a light intensity of 1/4L, and the light reflected from the workpiece 3 is further divided into two parts by the second half mirror 6b to illuminate the workpiece 3 with a light intensity of 1/4L.
The amount of light reaches camera 4. Therefore, the total amount of light for illuminating the workpiece is 1/2L+1/4L=3/4L, and the amount of light incident on the camera is 1/4L+1/8L=3/8L.

In order to compensate for such a loss in light quantity, it is sufficient to use a light source 1 with a large output, but as the device becomes larger, power consumption also increases, and the problem of heat generation occurs.

(Means for solving the problem) In order to solve the above problem, the illumination device according to this invention has a beam splitter arranged on the imaging optical axis connecting the subject and the imaging plane on which the subject image is formed. an illumination light source disposed on the beam splitter on a light source optical axis orthogonal to the imaging optical axis;
The illumination means is disposed on the opposite side of the illumination light source via the beam splitter on the light source optical axis and irradiates the subject with transmitted light that has passed through the beam splitter of the illumination light source. This illumination means is a total reflection mirror, an optical fiber, or the like.

(Function) In the vertical lighting section, the light from the illumination light source is
After being split into two by a beam splitter and illuminating the subject, the reflected light from the subject is split into two by the same beam splitter and enters the imaging plane. Therefore, when calculated in the same manner as in the above example, the amount of illumination light for the object is 1/2L, and the amount of light incident on the imaging surface is 1/4L. On the other hand, in the oblique illumination section, the light that is split into two by the beam splitter and transmitted illuminates the subject through illumination means such as a total reflection mirror, so the amount of illumination light is 1/2L, and the light reflected from the subject is Since the light passes through the same beam splitter and enters the imaging plane after being split into two, the amount of incident light is 1/2.
It is 4L. Therefore, the total light amount of the entire device is
The amount of illumination light for the object becomes 1/2L + 1/2L = L, and the amount of light incident on the imaging surface becomes 1/4L + 1/4L = 1/2L, which significantly improves light loss compared to 3/4L and 3/8L of conventional devices, respectively. Ru.

(Example) FIG. 1 shows an example of this invention. The illumination light source 11 is held in a lamp holder 12 having a heat sink on the outer periphery.
2 is a diffuser plate 13 and a condenser lens 14;
The light source mount 15 is screwed to the outer periphery of the right side of the light source mount 15 to which the light source mount 15 is fixed. A solid-state camera 17 having a solid-state imaging device 16 such as a CCD is screwed to the upper inner periphery of the light source mount 15, and a lens barrel 18 is fixed to the lower part thereof. If necessary due to space conditions, etc., the lamp holder 12 may be installed.
It is preferable that the solid-state camera 17 and the solid-state camera 17 can be attached by exchanging their positions. An objective lens 21 is attached to the lower part of the lens barrel 18 via an inner tube 19 and a screw spacer 20 that constitute a screw shift mechanism.
is attached, and the work surface 2, which is the subject
It is now possible to focus on 2. The center of the imaging surface of the image sensor 16 and the objective lens 2
1 and the light source optical axis P2 that connects the center of the light source 11 and the center of the condenser lens 14 are orthogonal to each other. A half mirror 23 serving as a beam splitter is adhesively fixed in the light source mount 15 with an inclination. A lamp holder 1 is installed on the left side of the light source mount 15.
Another lens barrel 24 is fixed at a position relative to 2. This lens barrel 24 has a bottom portion 24a, and a total reflection mirror 2 is disposed obliquely inside the bottom portion 24a.
5, and a condenser lens 28 attached via a screw-type spacer 27 in a hood 26 obliquely fixed to the lower side of the hood 26. The light source optical axis P2 is
It is bent by the total reflection mirror 25 and coincides with the imaging optical axis P1 on the work surface 22.

The light emitted from the light source 11 is diffused by the diffuser plate 13 to correct intensity unevenness, and then converted into parallel light by the condenser lens 14. A part of the light is reflected by the half mirror 23 and passes through the objective lens 21 onto the work surface. 22. The other part passes through the half mirror 23, is reflected by the total reflection mirror 25, and passes through the condensing lens 28 to illuminate the work surface 22. Therefore, the work surface 22 is irradiated with 100% of the light amount from the light source 11, and the reflected light from here passes through the half mirror 23 once and reaches the image pickup device 16, so that the light on the image pickup surface is The amount of incident light will be half that amount, 50%.

FIG. 2 shows another embodiment of this invention. This is intended to change the angle Θ by making the length of the lens barrel 24 variable so that there is no difference between the imaging optical axis P1 on the work surface 22 and the light source optical axis P2. Depending on the type of work surface 22 that is the subject, oblique illumination may not be suitable. For example, oblique illumination is inappropriate for illuminating a printed pattern, but oblique illumination is suitable for measuring surface roughness, detecting scratches and protrusions, and the like. Further, even when the lens barrel 24 is long and will interfere with other members, it is preferable to shorten the lens barrel 24 and use it.

A mechanism for making the length of the lens barrel 24 variable is, for example, as shown in FIG.
and an inner cylinder 242, which are fitted together, and a pinion provided on the outer cylinder 241 is engaged with a rack 243 provided on the inner cylinder 242, so that the pinion can be rotated from the outside by a knob 244.

When the length of the lens barrel 24 changes, the total reflection mirror 25
Since the direction of the optical axis P2 changes due to this, a mechanism is required to align this with the optical axis P1 on the work surface 22, an example of which is shown in FIG. The total reflection mirror 25 has a pin 25 at its lower end.
1 to the bottom 24a of the lens barrel 24, and its upper end is pulled upward by a tension coil spring 252 provided between the lens barrel 24 and the lens barrel 24. An adjustment screw 253 is provided hanging from the lens barrel 24.
Touch the lower end of the mirror 25 to the back side of the mirror 25, and screw 2
By turning 53 and moving it up and down, the angle α can be changed.

In yet another embodiment of this invention shown in FIG. 5, a light guide 29 is used instead of the assembly of the lens barrel 24, total reflection mirror 25, hood 26, spacer 27, condensing lens 28, etc. in the above embodiment. A condensing optical fiber 30 housed within is used. In this embodiment, the light guide 2
9 allows the optical path of the transmitted light from the half mirror 23 to be changed freely, so even if there is an obstacle inside the device, it can be avoided, and the irradiation angle Θ with respect to the work surface 22 can be changed freely. Therefore, it is even more convenient.

(Effect of the invention) As described above, the vision sensor illumination device according to this invention divides the light from the light source into two by one beam splitter, and simultaneously illuminates the subject from both the diagonal direction and the vertical direction without loss of light intensity. Since the reflected light guided from the subject to the imaging surface only passes through one beam splitter, the loss in the amount of light incident on the imaging surface is reduced by 50%.
It can be suppressed to %. Therefore, since a light source with relatively low output can be used as the illumination light source, it is possible to realize a compact lighting device that consumes less power and generates less heat.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of this invention.
FIG. 2 is a sectional view showing another embodiment of this invention;
FIG. 3 is a perspective view for explaining the details of part A of the embodiment shown in FIG. 2, FIG. 4 is a sectional view of the inner cylinder shown in FIG. 3, and FIG. FIG. 6, a sectional view showing another embodiment, is a schematic diagram showing an example of a conventional lighting device. 11...Illumination light source, 12...Lamp holder,
13...Diffusion plate, 14...Condenser lens,
15...Light source mount, 16...Image sensor, 1
7...Solid camera, 18, 24... Lens barrel, 21...
...Objective lens, 22...Work surface, 23...Half mirror, 25...Total reflection mirror, 28...Condensing lens.

Claims (1)

[Claims for Utility Model Registration] A beam splitter disposed on an imaging optical axis connecting a subject and an imaging plane on which the subject image is formed, and a light source on the beam splitter that is perpendicular to the imaging optical axis. an illumination light source disposed on the optical axis; and a transmitted light transmitted through the beam splitter of the illumination light source disposed on the opposite side of the illumination light source through the beam splitter on the light source optical axis. A visual sensor illumination device comprising: illumination means for illuminating a subject;