JPS61210484A - Optical symbol reading device - Google Patents

Abstract

PURPOSE:To obtain a large reading depth by providing an incoherent light source, measuring a distance from a symbol reading device to a symbol slip, thereby providing a focussing device for restrict an output light from the light source almost in the vicinity of the symbol slit. CONSTITUTION:An output of incoherent light source 1 is restricted to a desired beam diameter so as to form the focus on a symbol slit 11 by a focussing device receiving a measuring output of an range finder 12. An output light in which the beam diameter is restricted by the focussing device 2 passes through a conventionally same path and is inputted to a photoelectric converting element 8, via a videoamplifier 9 recognized by a decoder section 10 and outputted. In this manner, as the incoherent light source, an incandescant lamp or an LED luminescent element is used to a realize a symbol reading device of a high performance and having a large reading depth. An excessive layer tube and an exclusively used power source are not used, thereby a low cost reading device can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a symbol reading device, and particularly to a beam scanning barcode reading device used in logistics, POS systems, and the like.

[Conventional technology]

Conventionally, this type of reading device has used a laser beam whose beam diameter hardly expands as a light source in order to ensure stable reading performance against changes in distance from the symbol.

FIG. 8 is a block diagram of a conventional symbol reading device using this radar light.

The laser beam emitted by the laser wz1 is focused by a lens system 2z to a beam diameter necessary for reading, and then passed through a prism 8. Mirror 4. While being reflected by the polygonal rotating mirror 6 and the fixed mirror 7, the symbol tag 11 on which the bar code is written is focused onto the scanning line 28 and is scanned.

The reflected light scattered from the symbol tag 11 travels in the same optical path in the opposite direction, is redirected by the perforated mirror 5, is converted into an electrical signal by the photoelectric conversion element 8, is amplified and shaped by the video amplifier 9, and is sent to the decoder section. 10, and the determination result is output. The reading depth in this device is given by the distance z4 resulting in a beam diameter z5 equal to the size of the narrowest bar or space of the bar code symbol used, as shown in FIG. Laser light has good convergence and the beam diameter does not expand, so the reading depth is 2
4 has the advantage of being large.

[Problem that the invention seeks to solve]

As mentioned above, the conventional symbol reading MIN using the laser beam as a light source
(1) The laser output can be selected from the standpoint of safety for the human body, but the Sβ ratio is limited due to the noise generated, and (2) the reading device is expensive because the laser oscillator is expensive. There are problems such as it being difficult to reduce the price, and (3) users may have a vague sense of anxiety when handling Raded light, even if the design takes safety into consideration. It was an undeniable fact.

[Means for Solving the Problems] By using incoherent light as a light source, the present invention can ensure a reading depth comparable to that of conventional reading devices using laser light as a light source, and also enable cost reduction. This is what I did.

In other words, the optical symbol reading device according to the present invention uses a light source that emits incoherent light, a measuring means for measuring the distance from the symbol reading device to the symbol tag, and an output from the measuring means to enable the optical symbol reading device to move almost near the symbol tag. A focusing means for narrowing down the output light of the light source, a polarizing means for polarizing the output light, a light receiving means for receiving the reflected light from the symbol tag, a converting means for converting the output from the light receiving means into an electrical signal, and It is constituted by comprising decoding means for decoding the output of the converting means.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an optical symbol reading device according to the present invention.

This embodiment uses incoherent light as a light source instead of the laser beam in the conventional example shown in FIG. The apparatus is equipped with a distance meter 12 for measuring the distance, and a focus adjustment device 2 for focusing the output light of the incoherent light source 1 to approximately the vicinity of the symbol mark 11 based on the output from the distance meter 12.

The output light of the incoherent light source 1 is narrowed down to a required beam diameter by a focusing device that receives the measurement output of the range finder 12 so as to be focused on the mark 11.

The output light whose beam diameter has been narrowed down by the focusing device 11 is input to the photoelectric conversion element 8 through the same path as the conventional one shown in FIG. 8, passes through the video amplifier 9, is recognized by the decoder 10, and is output. be done.

FIG. 2 is an enlarged view of the vicinity of the focal point of the beam focused to the required beam diameter by the focusing device 2. When the barcode symbol is at position 18, it is at position 16, and when the symbol is at position 1
When it is at position 4.15, it is at position 17 and 18, respectively.
A focus adjustment device automatically adjusts the focus.

〔Effect of the invention〕

As explained above, the present invention includes a light source that emits incoherent light, a measuring device that measures the distance from a symbol reading device to a symbol tag, and a focal point that narrows the output light from the light source to approximately the vicinity of the symbol tag. By providing an adjustment device, (1) it becomes possible to realize a high-performance symbol reading device with a large reading depth using an incandescent lamp or LED light emitting device as an incoherent light source, and (2) it becomes possible to realize a high-performance symbol reading device with a large reading depth. By not using a dedicated power supply, a low-cost reading device can be provided, and (3) by not using a laser light source, it is possible to eliminate the sense of anxiety that laser light gives to the user.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the optical symbol reading device of the present invention, FIG. 2 is an enlarged view of the vicinity of the focal point of FIG. 1, and FIG. 8 is a block diagram of a conventional optical symbol reading device. FIG. 4 is a diagram showing the reading depth of the device of FIG. 8. 1... Incoherent light source, 2... Focus adjustment device. 8...prism, 4...mirror. 6... Hole mirror, 6... Polyhedral rotating mirror. 7...Fixed mirror, 8...Photoelectric conversion element. 9...Video amplifier, 10...Decoding section. 11... Symbol tag, 12... Distance meter. 18.14.15 ......Barcode symbol position. 16.17.18 ...Focus position. Figure 1 Figure 2

Claims (1)

[Scope of Claims] An optical symbol reading device for reading symbol tags on which symbols are written, comprising: a light source that emits incoherent light; and a measuring means for measuring the distance from the optical symbol reader to the symbol tag. , a focusing means for focusing the output light of the light source almost in the vicinity of the symbol tag according to the output from the measuring means; a deflection means for deflecting the output light; and a light receiving means for receiving the reflected light from the symbol tag. , a conversion means for converting the output of the light receiving means into an electrical signal, and a decoding means for decoding the output of the conversion means.