JPS6383886A - Bar code detector - Google Patents

Abstract

PURPOSE:To stably detect a bar code even when a detecting distance is changed by providing an automatic focus adjusting means to image-form the bar code on a two-dimensional image sensor. CONSTITUTION:An automatic focus adjusting means 7 is composed of a distance measuring part 8 and a converging means driving part 9. Since the spot of an infrared LED 10 irradiated on a bar code 2 is image-formed on a PSD 13 corresponding to the distance with the bar code 2, distance information can be obtained from a distance measuring signal processing circuit 14 by the principle of the triangulation from a PSD output current. A microcomputer 6 based on the distance information from the distance measuring part 8, counts the feeding quantity of a converging means 3, supplies a moving direction signal and a pulse signal to show a moving quantity to the converging means dividing part 9, and moves the converging means 3, so that the bar code enters the field depth of a two-dimensional image sensor 4.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a barcode detection device.

2. Description of the Related Art In a conventional barcode detection device of this type, as shown in FIG.
This reflected light is imaged on a two-dimensional image sensor 4 via a condensing means 3, converted into a bar width signal by a light reception signal processing circuit 6, and processed by a microcomputer 6. At this time, the condensing means 3 and the two-dimensional image sensor 4 were fixed. Therefore, the distance between the barcode 2 and the barcode detection device (hereinafter referred to as "detection distance") is limited to a fixed area due to the depth of field of the light condensing means 3.

Problems to be Solved by the Invention For this reason, when barcode detection is performed, it is necessary to bring the barcode label within the fixed area. For example, when detecting a barcode 2 affixed to an item flowing on a conveyor, the barcode 2 had to be positioned on the conveyor so that it fell within the area. Also,
If the type of item changes and the barcode 2 cannot be positioned within the area, the light focusing means 3 must be replaced with a suitable one. When using a barcode system for the purpose of improving productivity, there are problems in that the above-mentioned positioning equipment is required, and in flexible production, it is necessary to replace the light condensing means 3 and make adjustments accordingly. .

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides: illumination means for illuminating a barcode; light collection means for collecting reflected light from the barcode; The apparatus is equipped with a dimensional image sensor, and automatic focus adjustment means for adjusting the distance between the light condensing means and the two-dimensional image sensor to form an image of the code on the two-dimensional image sensor. .

Effects In the present invention, the above-mentioned configuration allows stable barcode detection even if the barcode detection distance changes.

Embodiment FIG. 1 shows an embodiment of the barcode detection device of the present invention. The light emitted from the illumination means 1 is reflected by the barcode 2, and the reflected light is imaged on the two-dimensional image sensor 4 via the condensing means 3. This light reception signal is converted into a bar width signal by the light reception signal processing circuit 5, and decoded by the microcomputer 6. In this embodiment, the illumination means 1 is a 100W halogen lamp, the condensing means 3 is f=30trrm, and the effective diameter is 3.
25 pieces of lens combination, 2D image sensor 4
A 6 bit x 256 bit 0GD two-dimensional sensor was used.

The automatic focus adjustment means 7 is composed of a distance measuring section 8 and a focusing means driving section 9. In the distance measuring section 8, the wavelength λ:''8
80 Light from infrared LED 1o with lid + output p9 = 5 mW,
The light is collected by a projection lens 11 with a focal length f=20rtan,
The barcode 2 is irradiated and the reflected light is focused at a focal length f=
An image is formed on a one-dimensional PSD 13 with a light-receiving surface length of 10 arcs through a light-receiving lens 12 of 20 m. The spot of the infrared LKD 10 irradiated onto the barcode 2 forms an image on the PSD corresponding to the distance to the barcode 2, so the distance measurement signal processing circuit 14 uses the PSD output current based on the principle of triangulation. You can get more distance information. The condensing means driving section 9 is composed of a condensing means driving circuit 15 and a condensing means driving mechanism section 16 composed of a pulse motor and a slide unit. 3Qw'Se ma, minimum positioning accuracy 0. lo
+ was adopted. The microcomputer 6 includes:
Based on the distance information from the distance measuring unit 8, the amount of movement of the light collecting means 3 is calculated so that the barcode 2 enters the depth of field of the light collecting means 4, and the movement direction is set in the light collecting means driving part 9. The condensing means 3 is moved by sending a signal and a pulse signal indicating the amount of movement.

Therefore, the barcode 2 always falls within the depth of field of the light collecting means 3.

FIG. 3 shows an example of operation when the barcode detection distance changes. First, in FIG. 3 (IL), it is assumed that the barcode 2 is located at a distance (rXJ) of 240 from the condensing means 3 (hereinafter referred to as rXJ). At this time, the distance (hereinafter referred to as "y") between the two-dimensional image sensor 4 and the condensing means 3 is set to 34.0 m. Depth of field is x = 240 + 3
0 m (A'), so barcode 2 can be detected. Next is barcode 2! = 58 TIrIL
Suppose that the position changes to ). Since this is outside the depth of field M' shown in FIG. 3(&), barcode 2 cannot be detected in the state shown in FIG. 3(a). Therefore, it cannot be detected by a conventional barcode detection device in which the positions of the two-dimensional image sensor 4 and the condensing means 3 are fixed and the depth of field is constant. However, in this embodiment, the distance measuring section 8 detects the position of the barcode 2 and moves the position of the condensing means 3. As a result, V = 46.6rran, and the depth of field is also great! ==128±3o deafness (B'). Therefore, barcode 2 can be detected. In this example, barcode detection was possible within a detection distance x of 98 to 270 m.

In this embodiment, a method in which the condensing means 3 is moved as the automatic focus adjustment means is adopted, but the same effect can be obtained by a method in which the two-dimensional image sensor 4 is moved. Furthermore, as an automatic focus adjustment method, it is also effective to use not only the distance measurement method described above but also a beat/beat detection method.

Effects of the Invention According to the present invention, it is possible to stably detect a barcode even if the barcode detection distance changes as described above, and therefore it is extremely useful for process control in high-mix, low-volume production.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a barcode detection device showing an embodiment of the present invention, Fig. 2 is a block diagram of a barcode detection device showing a conventional example, and Fig. 3 is an operation when the barcode detection distance changes. It is an explanatory diagram showing an example. 1...Lighting means, 2...Barcode,
3... Focusing means, 4... Two-dimensional image sensor, 7... Automatic focus adjustment means. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2? Figure 3 (α) (b)

Claims (2)

[Claims] (1) an illumination means for illuminating the barcode; a condensing means for condensing the reflected light from the barcode;
A barcode detection device comprising: a dimensional image sensor; and automatic focus adjustment means for adjusting a distance between the light condensing means and the two-dimensional image sensor to form an image of the barcode on the two-dimensional image sensor. (2) The automatic focus adjustment means includes a distance measuring section that detects the position of the barcode, and a focusing means driving section that moves the focusing means via a microcomputer based on distance information from the distance measuring section. A barcode detection device according to claim 1.