JP3843832B2 - Bar code reader - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical device that reads a barcode, and more particularly to an optical reader that improves the reading performance of a light receiving element.
[0002]
[Prior art]
As a conventional optical unit structure for reading a barcode, a patent application [Japanese Patent Application No. 2001-098605] is known as shown in FIG. The light emitting element 21 and the light receiving element 22 are press-fitted into the hole in the fiber holder 23, and there is a resin wall between the light emitting element 21 and the light receiving element 22, and light other than the reflected light from the bar code 24 receives the light receiving element 22. It is designed not to get in. In the patent application shown in FIG. 6 (Japanese Patent Application No. 08-185538), the light emitting element 31 and the light receiving element 32 are surrounded by resin, and light other than the reflected light from the barcode surface 34 enters the light receiving element 32. There is no such thing.
[0003]
[Problems to be solved by the invention]
In order to use a phototransistor, which is a low-priced light-sensitive element, in the conventional optical unit structure of a barcode reader, use a high-brightness LED with high cost or illuminate the barcode surface brightly using two LEDs. However, although a method has been adopted in which a large amount of reflected light from the barcode surface is put into the light receiving element, there is a problem that the cost increases.
[0004]
[Means for Solving the Problems]
The present invention has been made in view of the above-described problems. In a barcode reader that irradiates light emitted from a light emitting element onto a barcode surface and receives light reflected from the barcode by a light receiving element, the light emission is performed. A bar code reader is proposed in which a part of the boundary wall provided between the element and the light receiving element is cut out and a part of the light from the light emitting element is forcibly inputted as a bias to the light receiving element at a constant amount. Is.
[0005]
[Action]
In the present invention, the reflected light from the weak barcode can be used in the high sensitivity characteristic region and the high operation speed characteristic region of the light receiving element only by making a hole in a part of the light emitting element and the light receiving element. As a result, the barcode can be read well.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Light from the light emitting element is irradiated onto the barcode surface, and both the reflected light from the barcode surface and a part of direct light from the light emitting element are received by the light receiving element.
[0007]
【Example】
The details of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a sectional view of an optical unit portion of a barcode reader according to the present invention. The light emitting element 1 and the light receiving element 2 are soldered to the printed circuit board 3 and inserted into the holes of the fiber holder 4. In the groove 5 a of the fiber holder 4, the light emitting fiber 5 is in contact with and fitted into the light emitting element 1. In the groove 6 a of the fiber holder 4, the light receiving fiber 6 is fitted in contact with the light receiving element 2.
[0008]
The light emitted from the light-emitting element 1 is transmitted through the light-emitting fiber 5, is transmitted through the ball lens 8 from the other end of the light-emitting fiber 5, is irradiated onto the barcode surface 9, and the light reflected on the barcode surface 9 is The light is guided by the light receiving fiber 6 through the ball lens 8 and received by the light receiving element 2. If a light receiving element that is now low-cost and has low linearity at low illumination (due to dark current or leakage current) is used, and the reflected light from the barcode surface is weak, the light receiving element has low sensitivity and low operation at low illumination. Since the speed characteristic area is used, good reading cannot be performed.
[0009]
Now, a part of the wall 7 between the light emitting element 1 and the light receiving element 2 is cut out, and a certain amount of light emitted from the light emitting element 1 is directly input to the light receiving element 2 and reflected from the barcode surface. Add to the light. As a result of the addition, the area is raised from point A to point B as shown in FIG. 3, and a region with good linearity with good actual sensitivity and operating speed of the light receiving element can be used. The difference in small reflected light from white and black barcodes becomes a large signal difference, and white and black can be discriminated, and the ball lens 8 at the nib is sequentially displayed 14 from the barcode pattern 11 printed on the barcode surface. Move the nib up to. As for the output waveform, in the signal components of the barcodes 11 to 14, the output level of the white pattern is increased, the output level of the black pattern is decreased, and the difference between the output levels of white and black is A, and the barcode is read. Can do. The same effect can be obtained with an optical unit structure as shown in FIG.
[0010]
As can be seen from the above description, the barcode can be read satisfactorily with a simple structure in which a part of the wall between the light emitting element and the light receiving element is thinned.
[0011]
【The invention's effect】
The bar code reader of the present invention can read a bar code using a low-cost light receiving element.
[Brief description of the drawings]
FIG. 1 is a structural diagram of an optical unit according to the present invention.
FIG. 2 is an optical unit structure diagram 2 of the present invention.
[Fig. 3] Photosensitive device characteristic diagram [Fig. 4] Barcode compatible waveform diagram [Fig. 5] Conventional optical unit structure diagram 1
FIG. 6 is a structural diagram of a conventional optical unit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Light emitting element 2 Light receiving element 3 Circuit board 4 Holder 5 Light emitting plastic fiber 5a Groove 6 Light receiving plastic fiber 6a Groove 7 A part of wall 8 Ball lens 9 Barcode surface 11 Barcode white part 12 Barcode black part 13 Barcode White portion 14 Barcode black portion 21 Light emitting element 22 Light receiving element 23 Holder 24 Bar code 31 Light emitting element 32 Light receiving element 33 Holder 34 Bar code 35 Lens

Claims (1)

In a barcode reader that irradiates a barcode surface with light emitted from a light emitting element and receives light reflected from the barcode by a light receiving element, a boundary wall provided between the light emitting element and the light receiving element A bar code reader characterized in that a part of the light-emitting element is cut out and a part of light of the light-emitting element is forcibly inputted as a bias to the light-receiving element at all times.

Images