JPH01175686A - barcode reader - Google Patents

Abstract

PURPOSE:To obtain a wider reading distance range with the use of a small, economical, long life and safe light source such as an LED by providing a means to detect a distance to a bar code and controlling so that the bar code image of a best focus can be obtained on a sensor. CONSTITUTION:A focusing means VI previously programs the output of an ultrasonic sensor 14 and the moving quantity of a condensing lens 8 in order to obtain a bar code image being in focus on a pin photo diode 11 which is a sensor, receives the output signal of the ultrasonic sensor 14, moves the condensing lens by a driving mechanism 16 and forms an optimum LED beam on the bar code. Thus, a bar code reader can be formed with the use of a light source such as the LED light source which is small, economical, long life and excellent in a safety to eyes and an operationability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a barcode reader, and particularly to a non-contact handheld barcode reader.

Conventional technology Conventionally, in non-contact handheld barcode readers, as a solution to the fluctuation in the reading distance between the barcode and the barcode reader, as shown in Figure 3, the light source of the light projecting means is a highly focused laser. By scanning the barcode with a narrow aperture and collimated projection beam using light, it has been possible to read barcodes relatively stably even when the reading distance varies, even if the barcode is thin.

Now, Figure 3 is a typical example of the conventional example, where 1 is a barcode;
2 is a collimating light projection lens, 3 is a He-He laser, and the light projection lens 2 and the laser 3 constitute a light projection means It-. 4 is a light receiving lens, 6 is a bin photodiode as a sensor, and the light receiving lens 4 and sensor 6 constitute a light receiving means 11)
It is composed of r. 6 amplifies the sensor signal of sensor 6,
An analog circuit consisting of an operational amplifier for binarization, etc. 7 is a microcomputer that receives the output signal of the analog circuit 6, performs decoding processing, communication processing with the outside, and control of the light emitting means (2). The barcode signal detection means 111 is constituted by 6 and the microcomputer, and means ①.

This is a non-contact manual scanning type barcode IJ-DAIl configuration based on (1) and (2). In addition, instead of manual scanning, there is also a system in which a light scanning means such as a polygon mirror is provided between the light projecting means I and the barcode 1 to automatically scan the barcode.

Problem to be Solved by the Invention The reading distance range of a barcode is determined by whether the beam diameter of the He-Ne laser beam irradiated onto the barcode can detect the minimum bar width of the barcode. .

In the conventional example, as shown in FIG. 4, a He-Ne laser beam is irradiated onto the aperture barcode using a projection lens 2 so as to be as narrow and parallel as possible. In such a fixed focus method, the beam diameter is the detection limit mentioned above. Totori. The narrower beam diameter range, ie, the region L, becomes the distance region in which barcodes can be read. For example, in the case of a 0.2ff barcode, this area usually ranges from 1 to 6c.
rn, and bringing the barcode reader within that distance range without contact requires time and skill, and the operability has never been satisfactory. In addition, in order to obtain as wide a reading distance range as possible, He-Ne
This required an expensive and potentially eye-safe light source, such as a laser. In addition, since the He-He laser is incorporated, there are problems with the size and weight of the barcode reader itself, as well as maintenance (replacement is required because the Ha-He laser has a short lifespan).

Means for Solving the Problems The present invention provides a light emitting means, a light receiving means, a barcode signal detecting means for detecting a signal corresponding to a barcode from the light receiving means, and a distance detecting means for detecting the distance to the barcode. and a focusing point means for obtaining a focused barcode image on the light receiving means based on the result of the distance detecting means.

In the present invention, a means for detecting the distance between the barcode and the barcode reader is provided, and control is performed so that the best focus barcode image is always obtained on the sensor, which is the light receiving means. Instead of using a He-No laser as a light source, which is expensive, has eye safety issues, and requires maintenance, it is possible to use a small, inexpensive, long-life, and safe light source such as an I, HD. A wider reading distance range can be achieved using

Embodiment FIG. 1 shows an embodiment of the present invention. The light projecting means (■) uses LED9 with a wavelength of 660 nll as a light source.
, a light projection lens 8, and a lens drive mechanism 16 for moving the light projection lens 8.

The lens drive mechanism 16 includes a slider that moves the projection lens 8 in the axial direction and a pulse motor that drives the slider. Next, the light receiving means ■ is the light receiving lens 1
0 and a pin photodiode 11 having a filter attached to its surface that cuts light with a wavelength of 700 nm or more. The barcode signal detection means (■) includes an analog circuit 12 consisting of an amplifier circuit that amplifies the output of the pin photodiode 11, a differentiator circuit that cuts the DC component, and a binarization circuit that consists of an operational amplifier, a diode, and a capacitor. , and a microcomputer 13 that inputs the signal, decodes it, and outputs the result to an external POS or the like. Next, distance detection means V for detecting the distance to the barcode 1 is constituted by an ultrasonic sensor 14. The focusing means (2) programs the output of the ultrasonic sensor 14 and the movement of the condensing lens 8 in advance so that a focused barcode image is obtained on the bin photodiode 11, which is a sensor. In response to the output signal of the sonic sensor 14, the condenser lens 8 is moved by the drive mechanism 16,
It forms an optimal LED beam on the barcode, and is mainly composed of a microcomputer.

Further, this focusing point means (2) is linked to the barcode detection means (2) in order to notify the timing of the reading process.

The above-mentioned means (2), n, m, v, and w constitute a barcode reader (2). Now, in this embodiment, the ultrasonic sensor is capable of distance resolution up to 3B, and in the case of a 0.2 mackerel barcode, the detection distance range is 7 cr.
n, it was possible to detect 4 times/second. Figure 2 shows the movement of the minimum projected beam diameter position due to the movement of the 7 projecting lenses 8 of this embodiment. By using this control, the bar code is wider than the fixed focus type conventional example. The reading distance range is dynamically enabled.

In this embodiment, one microcomputer is used for the focusing point means (2) and the bar code signal detection means (2), but they may be integrated into one microcomputer. Further, the lens drive mechanism 16 may also drive LEDs. Furthermore, if not only the light projecting means (■) but also the light receiving lens 10 or the bin photodiode 11 of the light receiving means (2) are controlled to move so that the light beam on the barcode 1 is brought into focus in accordance with the focusing point operation of the light projecting means. more effective. Further, although this embodiment has shown an example in which there is no optical scanning means such as a polygon mirror between the light projecting means I and the barcode 1, the present invention is not limited thereto. In addition, as a light source, the wavelength e e o
Although a nm llCD is used, this does not limit the use of other wavelength LICDs or semiconductor lasers. Furthermore, an image sensor may be used as the light receiving sensor. Further, the distance detection means may be of an optical type.

Effects of the Invention As described above, according to the present invention, compared to a fixed-focus non-contact barcode reader using a conventional He-Me laser as a light source, it is possible to use an LED light source that is small, inexpensive, long-life, and easy to use. It is possible to realize a barcode reader that is significantly superior in terms of safety and operability, and its industrial effects are enormous.

[Brief explanation of the drawing]

Fig. 1 is a block circuit diagram of a barcode reader showing an embodiment of the present invention, Fig. 2 is a side view showing an example of light beam control by the same barcode reader, and Fig. 3 is a block diagram of a conventional barcode reader. The circuit diagram and FIG. 4 are side views showing an example of light beam control by the same barcode reader. 1... Barcode, ■... Light projecting means,
Lu...Light receiving means, ■...Barcode signal detection means, ■...Distance detection means, ■...Focusing point means. Name of agent: Patent attorney Toshio Nakao, 1st person, 2nd person
Figure 3 Figure 4

Claims (1)

[Claims] a light projecting means, a light receiving means, a barcode signal detecting means for detecting a signal corresponding to a barcode from the light receiving means;
distance detection means for detecting the distance to the barcode;
and a focusing point means for obtaining a focused barcode image on the light receiving means based on the result of the distance detecting means.