JPS6380220A - Forming method for optical bar - Google Patents

Abstract

PURPOSE:To form a continuous optical bar having roughly uniform width and luminance by forming an optical element by bundling optical fibers, and allowing a light beam to be made incident on this optical element almost perpendicularly to the axis thereof. CONSTITUTION:A light beam is made incident on an optical element almost perpendicularly to the axis thereof. That is to say, when a light beam 10 is radiated to an optical element 1, the light beam is made incident on an optical fiber 3 in the optical element 1, a part of the light beam transmits through this optical fiber 3 and refracted, the other part of the light beam is brought to a total reflection in this optical fiber 3, and thereafter, transmits through and refracted, and these transmission light beams proceed to other optical fiber 3 of the vicinity, and transmit, refracted and brought to a total reflection again. As a result, the light beam is diffused in all peripheral directions in the optical element 1 and emitted from the optical element 1. Subsequently, each transmission light which is emitted from many optical fibers 3 placed on the outside peripheral part of the optical element 1 interferes mutually, and a bright part of an optical bar 30 is formed continuously on a production of all peripheral directions of the optical element. The bright part of this optical bar 30 goes to that which has uniformly the luminance exceeding a prescribed value and the width exceeding a prescribed dimension.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming an optical par used in an optical scanning device or the like.

(Prior Art) In recent years, the industrial use of optical engineering in various industrial fields has become very popular. Many of them use light bars. For example, an optical scanning device illuminates a barcode with a light bar to read the numerical value (product price, etc.) displayed on the barcode, and an optical scanning device It has a wide variety of applications, such as examining the presence or absence of pinholes by shining a light bar on a specimen, or detecting the shape of a specimen by shining a light bar on the specimen and detecting changes in the shape of the light bar. There is.

FIG. 3 shows a conventional method of forming a light bar,
Reference numeral 1' in the figure is a glass cylindrical lens as an optical element, and its cross section is approximately semicircular.

According to the conventional method, a parallel light beam 10 emitted from a light emitting device (not shown) enters the cylindrical lens 1' almost perpendicularly from the flat surface 1a', and the transmitted light is refracted at the curved surface 1b' and is projected onto the screen 20. Light par 30″
is formed.

As is well known, the cylindrical lens 1' has the property of allowing light incident perpendicularly to the flat surface 1a' to travel straight without being refracted in the axial direction of the cylindrical lens 1'. Therefore, the vertical width of the light bar 30' is equal to the diameter d of the parallel beam 10.

The light bar 30' formed by the above conventional method has a bright part 30a' with high brightness and a dark part 30 with low brightness.
0b'. Further, the vertical width of the bright portion 30a' is equal to the diameter d of the parallel light beam 10 in the central area 20a of the screen 20, but the width in both sides 20b of the screen 20 is equal to the diameter d of the parallel beam 10.
It is gradually narrowing down.

The above phenomenon is interpreted as follows. In FIG. 4, the cylindrical lens 1' has different focal points depending on the distance of the incident light ray from the optical axis C0. Immediately, the focal point for the paraxial ray C1 near the optical axis C0 is F, and the focal point for the peripheral ray C2 far from the optical axis C0 is F2, and the focal point F2 is 9 9 above the focal point F1. Also cylindrical lens 1
′ is approaching. Therefore, when a flat screen 20 is placed at the focal point F, the transmitted light CI' of the paraxial ray C1 is condensed and projected onto the focal point F on the screen 20, resulting in extremely high illumination and brightness. On the other hand, the transmitted light C2' of the marginal ray C2 is diffused after passing through the focal point F2, and is projected over a wide range on the screen 2O, so that the illuminance becomes low and the brightness becomes low.

(Problems to be solved by the invention) By the way, the conditions for an industrially usable light bar are as follows:
Luminance greater than a predetermined value and vertical width greater than a predetermined dimension are required, and if a light bar that does not meet these conditions is used, it will be impossible to maintain a predetermined detection accuracy.

For this reason, the industrially usable portion of the conventional light bar 30 is the screen 20 in FIG.
There was only a bright portion 30a' in the central region 20a projected onto the image.

As a result, in the above-mentioned application example, there are limitations on the width of the barcode, the size of the specimen to be inspected, etc. In order to compensate for this drawback, it is necessary to increase the number of times the optical scanning device runs, which makes the work complicated and inefficient.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and its gist is to provide a method for making light incident on an optical element and forming a light bar using the transmitted light. A large number of optical fibers are bundled to form an optical element, and light is incident almost perpendicularly into the fine core of this optical element, and after passing through each of the optical fibers, the transmitted light is emitted from the optical element in the entire circumferential direction. , a method of forming a light bar characterized by obtaining a light bar having substantially uniform width and brightness.

(Function) When light is irradiated onto an optical element, the light enters the optical fiber inside the optical element, some of the light is transmitted through this optical fiber and refracted, and the other part of the light is totally reflected within this optical fiber. After that, the transmitted light is transmitted and refracted, and these transmitted lights proceed to other nearby optical fibers, where they are transmitted, refracted, and totally reflected again.In this way, the light is successively refracted and totally reflected by a large number of optical fibers within the optical element. Repeat the reflection. As a result, the light is diffused in the entire circumferential direction within the optical element and is emitted from the optical element.

The transmitted light beams emitted from a large number of optical fibers arranged around the outer periphery of the optical element interfere with each other to continuously form a bright part of the light bar on an extended line in the circumferential direction of the optical element. The bright portion of this light bar uniformly has a luminance of a predetermined value or more and a width of a predetermined dimension or more.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings of FIGS. 1 and 2. Note that the same parts as in FIG. 3 will be described with the same reference numerals.

FIG. 1 shows a method of forming an optical path according to the present invention, and reference numeral 1 in the figure indicates an optical element of a conduit. This optical element 1 is made by bundling a very large number of glass optical fibers, and the cross section of the optical element 1 manufactured in this way is as shown in FIG. That is, the cladding 2 of each optical fiber is melted and integrated, and the cores 3 of each optical fiber are evenly distributed in large numbers within this cladding 2.
A protective layer 4 made of glass is formed on the outer peripheral surface of the optical element 1.

Although the number of cores 3 in FIG. 2 is over a hundred for convenience of illustration, in reality, the number of cores 3 is in the order of ten thousand.

Then, a parallel light beam 10 having a diameter d is irradiated perpendicularly to the axis of the optical element 1 from a light emitting device (not shown).

The parallel light beam 10 is slightly refracted when it enters the protective layer 4, and is refracted again when it enters the cladding 2 from the protective layer 4. A parallel light beam 10 that has passed through the cladding 2 is refracted and incident on a large number of cores 3 arranged around the outer circumference of the optical element 1. The rays incident on each of these cores 3 are
Due to the difference in the angle of incidence from the core 3 to the cladding 2, some light rays pass through the core 3 and are refracted when exiting from the core 3 to the cladding 2, while other light rays are totally reflected at the boundary surface. The light travels inside the core 3, is refracted at the boundary surface, and is emitted to the cladding 2. The cladding 2 passes through these cores 3.
The light beam that enters the core 3 enters other cores 3 in the vicinity on the optical path. In this core 3 as well, refraction and
Total internal reflection takes place.

In this way, each ray of the parallel ray bundle 10 is successively diffused in all directions within the optical element 1, and eventually passes from each core 3 disposed on the outer periphery of the optical element 1 to the cladding 2 and the protective The light is emitted almost uniformly through the layer 4 toward the entire circumference of the optical element 1.

It is expected that each light bar formed by each transmitted light emitted from each core 3 on the outer periphery of the optical element 1 has the same illuminance distribution and brightness distribution as before. However, since there are an extremely large number of cores 3 arranged on the outer periphery, and the transmitted light is emitted in the entire circumferential direction, each transmitted light interferes with each other, as shown in Fig. 1. The light bar 30 projected onto the curved screen 20 disposed at a predetermined distance from the optical element 1 has a substantially uniform width h (h=d) along its entire length and a predetermined brightness. The light bar 30'' has a continuous bright area, and no dark area is formed as in the case of the conventional light bar 30''.

Therefore, the entire length of the optical par 30 is within an industrially usable range, and is extremely long compared to the conventional optical par 30'.

It has been confirmed that the same optical pars 30 as described above are formed even when the screen 20 is flat like the conventional one.

Furthermore, since the transmitted light from the optical element 1 is emitted in the entire circumferential direction, if the screen 20 is made cylindrical and arranged concentrically with the optical element 1, an annular light bar that goes around the screen 20 is formed. 30 is formed.

As explained above, this optical par 30 has approximately uniform brightness due to mutual interference between the transmitted light beams emitted from the optical element 1, so when viewed microscopically, it has some interference fringes. ing. Therefore, if it is desired to remove these interference fringes depending on the purpose of use of the light bar 30, the interference fringes are removed by rotating the optical element 1 at a constant speed around its axis at a constant speed.

This invention is not limited to the above-mentioned embodiments, and various embodiments are possible.

(Effects of the Invention) As explained above, according to the present invention, optical fibers are bundled to form an optical element, and the light is made to enter almost perpendicularly to the axis of the optical element. The light is repeatedly refracted and reflected within the optical element, and is emitted from the optical element in the entire circumferential direction, thereby forming a continuous light bar having substantially uniform width and brightness.

Therefore, it is possible to form a very long optical bar that can be used industrially, and the length restrictions in the optical bar utilization technology are greatly relaxed.

[Brief explanation of the drawing]

The drawings in FIGS. 1 and 2 show an embodiment of the present invention, and FIG. 1 is a schematic perspective view showing a method of forming an optical hole;
FIG. 2 is a schematic sectional view of an optical element used in the present invention. FIGS. 3 and 4 show the prior art. FIG. 3 is a perspective view of the prior art equivalent to FIG. The figure is a geometrical optical line diagram showing the principle. DESCRIPTION OF SYMBOLS 1... Optical element, 2... Clad (optical fiber), 3... Core (optical fiber), 10... Light (parallel beam bundle), 30... Light bar.

Claims (1)

[Claims] In the method of making light enter an optical element and forming a light bar with the transmitted light, a number of optical fibers are bundled to form an optical element, light is made almost perpendicular to the axis of this optical element, and each of the above-mentioned optical fibers is 1. A method for forming a light bar, which comprises transmitting light and then emitting the transmitted light from an optical element in the entire circumferential direction to obtain a light bar having substantially uniform width and brightness.