JPS63182623A - Projector - Google Patents

Abstract

PURPOSE:To vary the beam diameter of a projection light beam optionally and to facilitate optical-axis adjusting operation, etc., by arranging two cylindrical lenses in front of a light emitting element so that their optical axes are aligned with the optical axis of the light emitting element, and allowing one cylindrical lens to rotate on its optical axis. CONSTITUTION:A semiconductor laser 12 as the light emitting element is arranged in the case 11 of a projector 10 and the two plane cylindrical lenses 1 and 2 are provided in front of the laser so that the optical axes are aligned; and the cylindrical lenses 1 and 2 are supported on the case 11 rotatably on their optical axes. Thus, the lens 2 is rotated, to the projection light beam of the projector 10 is deformed from a collimated beam to a diverged beam or vice versa and its diameter is varied optionally. Consequently, the beam diameter of the projection light beam is increased to perform positioning and then the beam diameter is reduced gradually to make a highly accurate adjustment, thereby facilitating the operation.

Description

DETAILED DESCRIPTION OF THE INVENTION Summary of the Invention The optical system of a light projector such as a photoelectric switch is composed of two flat cylindrical lenses, and at least one of the cylindrical lenses is rotatable around an optical axis. This allows the output beam pattern to be changed to any size.

Optical axis adjustment is now easier when setting up the emitter and receiver.

TECHNICAL FIELD This invention relates to a light projector, such as a light projector for a photoelectric switch.

Prior Art and Its Problems Photoelectric switches are widely used in various production lines and manufacturing processes because they can detect the presence or absence of an object to be detected in a non-contact manner at a location away from the object to be detected.

In order to meet the recent demands for miniaturization of detected objects and longer detection distances.

Photoelectric switches that use semiconductor lasers as light sources have appeared.

However, in a photoelectric switch that uses a semiconductor laser as a light source, especially a transmission-type photoelectric switch in which an emitter and a receiver are arranged facing each other and a semiconductor laser is used as the light source of the emitter, the output light beam of the semiconductor laser Since the diameter of the beam is small and its spread angle is also small, it is very difficult and time-consuming to adjust the optical axis when installing the emitter and receiver.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a projector that can arbitrarily change the beam diameter of an emitted light beam, and to facilitate the above-mentioned optical axis adjustment.

Structure and Effect of the Invention In the projector according to the present invention, two cylindrical lenses are arranged in front of a light emitting element as a light source so that their optical axes coincide with the optical axis of the light emitting element, and at least one of the cylindrical lenses is arranged in front of a light emitting element as a light source. It is characterized by a cylindrical lens that is rotatable around the optical axis. As a light emitting element as a light source, not only a semiconductor laser but also a light emitting diode or the like can be used.

According to this invention, at least one cylindrical
By rotating the lens, the beam of light emitted from the projector can be adjusted.
It is possible to change the diameter arbitrarily by transforming the beam from a collimated fist beam to a diverging beam or vice versa. Therefore, when adjusting the optical axis, first increase the beam diameter of the emitted light beam, determine the approximate position, and then gradually reduce the beam diameter to achieve highly accurate adjustment. becomes easier. Also, when the floodlight of this invention is applied to a photoelectric switch.

This is convenient because the optimum beam pattern can be selected depending on the size of the object to be detected and the detection distance.

DESCRIPTION OF EMBODIMENTS First, a cylindrical lens used in the present invention will be explained.

FIG. 1A shows what is called a flat cylindrical lens, which is a type of Fresnel lens. A conventional cylindrical lens equivalent to the rectangular portion a shown in broken lines in FIG. 1(A) is shown in FIG. 1(B). In this specification, the direction in which no light condensing action occurs, as shown by the arrows in FIGS. 1(A) and 1(B), is defined as the direction of the lens. The outer shape of the flat cylindrical lens shown in FIG. 1 (^) is circular. This is because the lens has a shape suitable for rotation as will be described later, and the outer shape of the lens may be rectangular or other shapes.

Although FIG. 1A schematically shows a flat cylindrical lens, FIG. 2 shows a slightly exaggerated shape of the rectangular portion a. As can be seen from this figure, the flat cylindrical lens is composed of a linear concavo-convex pattern that extends in one direction. Although a blazed uneven pattern is shown, a stepped pattern may also be used. The depth of the unevenness is, for example, usually about 1 μm. As a result of Fresnel diffraction of the incident light by such a concavo-convex pattern, the light is focused to form a linear spot. The longitudinal direction of this linear spot coincides with the direction of the cylindrical or lens indicated by the arrow in FIG. 2 as well.

The flat cylindrical lens as described above can be integrally molded from transparent resin by injection molding or other methods.

The female mold of the flat cylindrical lens for resin molding can be made in various ways, for example, as follows.

An electron beam resist is applied onto a predetermined substrate, a flat cylindrical lens pattern is drawn on the resist by electron beam lithography, and then this resist is developed. Then, the remaining resist pattern on the substrate is transferred to the substrate by dry Φ etching. This board becomes the female mold (
(See patent application No. 81-3419).

Alternatively, a female mold is formed by electroforming using the above residual film resist pattern as a male mold. That is, the remaining resist pattern is plated with metal.

After that, by dissolving the remaining film pattern and the substrate with an organic solvent, only the metal plating part is left (patent application Sho Bl.
-3420).

FIG. 3 shows an embodiment of the invention. A semiconductor laser 12 as a light emitting element and two flat cylindrical lenses 1.2 arranged in front of the semiconductor laser 12 are provided in a case 11 of the projector 10. The optical axes of the semiconductor laser 12 and lenses 1 and 2 coincide with each other. Cylindrical lens 1 is fixed to case II, and lens 2 is supported by case If so as to be rotatable about its optical axis.

Even if the lens 2 is directly supported by the case 11, the lens 2
is fixed to the holding member, and this holding member is attached to the case.

11 so as to be rotatable. The lens 2 or its holding member is provided with a knob 2a for rotating the lens 2 for purposes such as optical axis adjustment, as will be described later. It is of course possible to rotate the lens 2 not by manual rotation but by a motor or the like.

In Figure 3, two flat cylindrical lenses l
The directions of and 2 are orthogonal. As a result, almost perfectly circular collimated light can be obtained as described later.

FIG. 5 is an analytical representation of the optical system shown in FIG. 3, and FIG. 4 shows the coordinate system used in FIG.

The optical axis of the semiconductor laser 2, ie, the propagation direction of the emitted laser beam, is the Z-axis. As is well known, the spread angle of the emitted light from a semiconductor laser is different in the horizontal direction and the vertical direction. Therefore, the direction in which the spread angle of the laser emitted light shows the maximum value (the maximum angle is assumed to be β) is taken as the Y-axis direction. In the X-axis direction, the spread angle of the emitted light is the minimum (the minimum subnormal angle is α). In FIGS. 5A and 5B, the flat cylindrical lens 1.2 is depicted as a conventional cylindrical lens with a convex surface for better clarity.

FIG. 5(A) shows the Y-Z plane. In this Y-Z plane, the focal length of the lens 1 and the distance between the lens 1 and the laser are adjusted so that the emitted light component (spread angle β) of the semiconductor laser 12 that diverges in the Y direction is collimated by the first cylindrical lens 1. 12 is determined. The light collimated by the first lens 1 is
is not affected at all by lens 2.

FIG. 5(B) shows the X-Z plane. In this plane, the focal length of the second lens 2 is adjusted so that the light component (spread angle α) emitted from the semiconductor while spreading in the X direction of the semiconductor I2 is collimated by the second lens 2. The distance to the laser 12, etc. are determined. Within this XZ plane, the light emitted from the semiconductor laser 12 is not affected by the first lens 1 at all.

FIG. 5(C) shows a cross section taken along line CC in FIG. 5(B). As described above, the emitted light from the semiconductor laser is collimated in the Y direction and the X direction, respectively, so the cross section of the collimated light becomes a perfect circle.

Figure 6 shows the second flat cylindrical lens 2 at 90°.
A state in which the lens is rotated so that the direction of the lens is the same as that of the first lens 1 is shown. FIG. 7 shows analytically the optical system of FIG.

In FIG. 7(A), the light component collimated by the first lens 1 is focused at a point P by the second lens 2, and thereafter becomes diverging light.

In FIG. 7(B), X of the emitted light from the semiconductor laser 12 is
The directional component is completely unaffected by either of the two lenses 1 and 2 and propagates while diverging at a spread angle α. Therefore, a point farther than one point P, that is, FIG. 7 (B
), the light beam cross section becomes a fairly thick ellipse as shown in FIG. 7(C).

Not only the second flat cylindrical lens 2 but also the first
The assembled plate-like cylindrical lens 1 may also be rotatable. By suitably adjusting the rotation of these lenses 1 and 2, it is possible to arbitrarily change the divergence angle in the X and Y directions of the laser beam that diverges after the position P of the focal point P.

By rotating at least one of the cylindrical lenses as described above.

The light beam emitted from the projector 10 can be a collimated beam or a diverging beam, and the two divergence angles can be changed arbitrarily. therefore.

When this projector 10 is used as a projector for a transmission type optical switch, optical axis adjustment becomes easy.

Optical axis: A state of alignment is shown in FIG. First, as shown in FIG. 8(A), the spread angle of the projected light beam of the projector 10 is increased, and the optical axes of the projector and receiver are aligned within a rough range. ), the divergence angle of the projected light beam is gradually reduced to achieve more accurate optical axis alignment, and after i &
), the optical axes of both instruments are finally aligned to create almost completely collimated light.

Although the projector according to the present invention can be used in a variety of applications other than photoelectric switches, there may be cases in which it is not necessary to ultimately convert the projected light beam obtained from the projector into a collimated beam in all of the various applications. Even with a transmissive type 9 reflective photoelectric switch, it is possible to use the 9 projected light beam with a slightly divergent light depending on the position, size, detection ability, etc. of the object to be detected, and it is better to do so. In some cases it may be preferable.

In the above embodiment, a flat cylindrical lens is used as the cylindrical lens.

Since this flat cylindrical lens can be made of plastic as mentioned above, it can be made smaller and lighter than conventional optical cylindrical lenses with convex surfaces, making the optical system of the projector more compact. It is possible to summarize.

[Brief explanation of the drawing]

Figure 1 is for explaining a cylindrical lens. Figure 1 (A) is a schematic diagram of a flat cylindrical lens, and Figure 1 (B) is a perspective view of a conventional cylindrical lens with a convex surface. Figure 2 is shown in Figure 1 (
It is a perspective view which expands and shows the shape of a part of flat cylindrical lens shown in A). 3 to 7 show embodiments of the invention. FIG. 3 is a perspective view showing the structure of the projector, showing the case where the directions of the two cylindrical lenses are orthogonal;
Figure 4 shows the coordinate system of the optical system, and Figure 5 shows the optical system in Figure 3 analytically, with Figure 5 (A) showing the y-z plane, and Figure 5 (B) showing the y-z plane. Figure 5(C) shows the cross section along the line C-C of Figure 5(B), and Figure 6 shows the internal configuration of the projector when the directions of the two cylindrical lenses are parallel. 7 shows the optical system of FIG. 6 analytically, FIG. 7(A) shows the Y-Z plane, and FIG. 7(B) shows the optical system shown in FIG.
is the X-Z plane, and Figure 7 (C) is the C-C plane of Figure 7 (B).
Each line cross section is shown. FIGS. 8(A), 8(B), and 8(C) show how the spread angle of the light beam emitted from the projector is gradually reduced during optical axis adjustment. 1.2... Flat cylindrical lens. 10... Floodlight, 11... Case. 12... Semiconductor laser. that's all

Claims (1)

[Claims] In front of the light emitting element, two cylindrical lenses are arranged so that their optical axes coincide with the optical axis of the light emitting element, and at least one of the cylindrical lenses
The lens is a floodlight that is supported rotatably around the optical axis.