JPS59100988A - Marked character reader - Google Patents

Abstract

PURPOSE:To obtain a sufficiently high contrast between a flat part and a character part by using two optical fiber arrays with their tips set approximate to the surface of an object to be read. CONSTITUTION:A contact is secured between the bottom surface of a view camera 9 and the surface of an object 2 to be read, and the surface of the object 2 is irradiated by the 1st optical fiber array 5. Then the reflected light from the surface of the object 2 is made incident to a line sensor 7 through the 2nd optical fiber array 6. The intensity ratio of reflected light is generally set at 10-40 between the recess of a character part and the flat part (non-character part) on the surface of the object 2. Thus it is possible to obtain a sufficiently high contrast between the flat part and the character part when the camera 9 has a scan on the surface of the object 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a character reading device, and more particularly to a device for reading engraved characters formed by unevenness on the surface of an object.

(b) Background of the technology Engraved characters formed by creating irregularities on the surface of objects are widely used for decoration and other purposes, but for industrial products, product numbers and other information are printed on the product components themselves or on nameplates, etc. It has been used for a long time as a way to record information in a way that it cannot be erased.

In recent years, as the automation of manufacturing processes has progressed, there has been a demand for the development of a device that can automatically read the information recorded by such stamped characters, but so far no effective method has been found. Not yet.

(C) Prior Art and Problems In order to meet the above-mentioned demands, conventionally, as shown in FIG. A method has been used in which the reflected light from the surface of the object 2 to be read is focused by a lens 3 to form an image of the character to be read on the image sensor 4.

However, in general, the above-mentioned engraved characters have no difference in color or reflectance from the flat part (non-engraved character part), and the engraved characters are formed compared to the distance lN11 between the object to be read 2 and the lens 3. Since the depth of the unevenness is extremely small, there is no large difference in the intensity of reflected light from the engraved character portion and the flat portion.

That is, the contrast between the imaged character pattern and its hacking ground becomes extremely weak, resulting in a disadvantage that the reliability of reading is reduced.

(d) Object of the Invention The object of the present invention is to provide a stamped character reading device that can read characters formed by unevenness provided on a plane with high reliability and that can be miniaturized.

<e> Structure of the Invention The present invention provides an apparatus for optically reading engraved characters, which includes: a light source for irradiating light onto an object to be read; a line sensor for detecting reflected light from the object; a first optical fiber array whose tips are provided close to the surface of the object to be read in order to project the light from the light source onto the surface of the object to be read; In order to guide light to the line sensor, it is characterized by comprising a second optical fiber array, the tip of which is provided close to the surface of the object to be read.

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

In the following drawings, the same parts as in the previous figures are given the same reference numerals.

FIG. 2 is a diagram showing the principle of the present invention, and as shown in FIG. A first optical fiber array 5 and a second optical fiber array 6 are provided so as to be perpendicular to each other. In this case, one end of the optical fiber array 5 of ff1l is placed close to the light source 1, and one end of the second optical fiber array 6 is placed in contact with the line sensor 7. Furthermore, the other ends of each optical fiber array are arranged substantially perpendicularly to and close to the surface of the object to be read 2 so as to be in contact with each other.

As shown in FIG. 2(B), the light source 1, each optical fiber array, and the line sensor 7 are housed inside a dark box 9, which has an opening 8 on the bottom surface in contact with the object to be read 2. In this case, the tip of each optical fiber array faces the surface of the object to be read 2 through the opening 8 in close proximity.

FIG. 3 is a diagram that does not show the arrangement of the first optical fiber array 5 and the second optical fiber array 6 as seen through the aperture 8.

When the bottom surface of the dark box 9 having the above configuration is brought into contact with the surface of the object to be read and the surface of the object to be read 2 is irradiated with light by the first optical fiber array 5, the reflected light from the surface of the object to be read 2 is reflected from the surface of the object to be read. The light enters the line sensor 7 through the optical fiber array 6. In this state, the dark box 9 is scanned over the characters to be read.

In this case, the intensity ratio of the reflected light between the flat part (non-character part) of the surface of the object to be read 2 and the depression of the character part is (d+I)2/
It becomes d2. However, as shown in FIG. 4, d and l are the distance between the tip of each optical fiber array 5 and 6 and the flat part 22 of the object to be read 2, and the indentation of the character part measured from the flat part 22, respectively. This is the depth of the bottom 23 of .

Generally, d is about 0.1 to 0.2u, and 1 is about 0.5mm, so the intensity ratio of the reflected light is 10
-40, and when the dark box 9 is scanned over the surface of the object to be read, a sufficiently clear contrast can be obtained between the flat part and the character part.

In the conventional method shown in FIG. 1, it is not possible to bring the light source 1 and the lens 3 close to the surface of the object to be read 2 on the order of the depth of the recess, and therefore, it is not possible to bring the light source 1 and the lens 3 close to the surface of the object to be read 2 on the order of the depth of the recess. However, by using optical fibers as in the present invention, it is possible to obtain a large contrast ratio between the reflected light from the It can be done.

The address signal of the character pattern to be read can be obtained by scanning the engraved character reading device having the above configuration over the object to be read at a constant speed and sampling the output signal of the line sensor at regular intervals during this scanning.

FIG. 5 shows another embodiment of the present invention, in which the optical axes of the first optical fiber array 5 and the second optical fiber array 6 are arranged at an angle with respect to the surface of the object 2 to be read.

Generally, as the angle of incidence θ approaches 90°, the reflectance increases to 1.
Therefore, by tilting each optical fiber array as shown in FIG. 5, the light utilization efficiency can be increased, and the light source 1 may have a small output capacity.

FIG. 6 shows a configuration in which the first optical fiber array 5 and the second optical fiber array 6 are stacked so as to be densely packed in the cross section of their tip portions. By adopting such a configuration, the ratio of the single beam of light incident on the second optical fine array 6 can be increased, and the efficiency of light utilization can be improved.

FIG. 7 shows a case where the optical fibers constituting the first optical fine array 5 and the optical fibers constituting the second optical fine array 6 are arranged alternately at their tips. By doing so, the thickness of the entire optical fiber array can be reduced,
It is effective when the width of the recess is small and one character is to be read.

FIG. 8 shows an example in which a lens 10 is provided at the tip of the first optical fiber array 5.

As shown in FIG. 2A, the lens 10 is arranged so that the projected light from the first optical fiber array 5 is focused exactly on the flat portion 22 of the surface of the object 2 to be read.

Therefore, the projected light is strongest at the flat portion 22, and is expanded and weakened at the bottom 23 of the recess, and the contrast of the reflected light at both portions becomes even greater than in the case where the lens 10 is not provided.

In each of the above embodiments, a method may be adopted in which the tips of each optical fiber array on the side facing the surface of the object to be read are independently supported, but it is also possible to use a method in which these tips are fixed to each other with resin or the like. By adopting such a structure, the mutual positional relationship can be accurately maintained, and the positional adjustment with respect to the object to be read can also be facilitated.

In the above embodiment, the case where an engraved character formed by a depression is read is explained as an example, but in the case of a protruding engraved character, in the formula for calculating the intensity ratio of reflected light, d is replaced by an optical fiber. By making the distance between the tip of the array and the protruding engraved character and l correspond to the height of the engraved character, the contrast between the character part and the non-character part can be sharpened in exactly the same way. , the characters can be read.

(g) Effects of the Invention According to the present invention, the engraved characters formed with unevenness can be
A relatively simple configuration enables reading with high reliability, and has the effect of providing a compact reading device.

[Brief explanation of drawings]

Figure 1 is a diagram showing the configuration of a conventional stamped character reading device;
FIG. 1'σ is a diagram showing an embodiment of the engraved character reading device according to the present invention. In the figure, 1 is a light source, 2 is an object to be read, 3 is a lens,
4 is an image sensor, 5 is a first optical fiber array, 6 is a second optical fiber A-array, 7 is a line sensor, 8 is an aperture, 9 is a dark box, 10 is a lens, 21 is a character string, 22 is a flat surface 23 is the bottom of the recess. Fig. 1 Fig. 2 Haze <A) (B) Fig. 3 Fig. 4 Mouth

Claims (3)

[Claims] (1) A light source for irradiating light onto an object to be read, a line sensor for detecting reflected light from the object to be read, and a line sensor for projecting light from the light source onto the surface of the object to be read; a first optical fiber array, the tip of which is disposed close to the surface of the object to be read; An engraved character reading device comprising: a second optical fiber array provided close to the surface. (2) The engraved character reading device according to claim 1, characterized in that the first optical fiber array and the second optical fiber array are integrated at the tip end on the side of the object to be read. (3) The engraved character according to claim 1, characterized in that the optical fibers of the first optical fiber array and the second optical fiber array are arranged alternately at the tip of the object to be read. Reading device b (4) The engraved character reading device according to claim 1, characterized in that a lens is provided at the tip of each optical fiber of the first optical fiber array on the side to be read.