JPS6373489A - Optical reading device - Google Patents

Abstract

PURPOSE:To optionally set the color of a readable character and a bar code by providing an optical filter at the light path of a reading system. CONSTITUTION:A light irradiated to a paper 1 from a light source 3 is reflected by the paper 1, and the reflecting light is image-formed in one side through a reflecting mirror 5 and a lens system 8 to an image sensor 10 and in other side, image-formed through an optical filter 7 and a lens system 9 to an image sensor 11. The optical filter 7 is the filter to pass through only the light of a special wavelength or wavelength area and at the image sensor 11, only the bar code of the special color is image-formed. At the above-mentioned both light paths, the optical filter to pass through only the light of the respectively mutually different wavelength area may be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a hand-held optical reading device for optically reading characters and bar codes.

0) Prior Art Optical reading devices are used in the distribution industry and the like to read the price and product code of each product written in characters or barcodes and input them into a computer.

Characters are numbers and alphabets that represent prices and product codes. A barcode is a large number of thick lines and thin lines arranged in parallel.

When characters are read optically, it is called optical character reading.

If a barcode is read optically, it should be called optical barcode reading.

The present invention is called an optical reader because it reads both characters and barcodes.

Hereinafter, when distinguishing between characters and barcodes, they will be written as "characters" or "barcodes." To include both, "
It will be called ``characters, etc.''.

An optical reading device shines light on characters written on a medium to be read (such as a label), uses a lens system to form an image of the reflected light on an image sensor, and converts the intensity of the light amount into the intensity of an electrical signal. Electrical signals are binarized depending on their strength to form a character area and a background area, and characters and the like are identified based on the binarized signals.

Image sensors include -dimensional image sensors and two-dimensional image sensors. -Dimensional image sensor.

In this case, the scanning of the image by the image sensor array itself is called main scanning. The scanner is moved by hand in a direction perpendicular to the direction in which the image sensors are arranged, and this type of manual scanning is called sub-scanning.

In the case of a two-dimensional image sensor, it is possible to read characters in a certain range without manual sub-scanning.

1) Problems with the Prior Art The sensitivity of image sensors used in conventional optical reading devices has wide wavelength characteristics with a peak in the far-infrared region.

Characters that describe product prices and product codes are usually written in black.

Barcodes may or may not be written in black. Barco Y is often printed in the same color as the product box or bag.

Colors that cannot be read by optical reading devices are called dropout colors. Characters that can be read are
It can be read because it can be distinguished from the background area (that is, white).

A color that cannot be distinguished from the background area becomes a dropout color.

Since the dropout color cannot be distinguished from the background area, it is treated as the same as the paper color (eg, white).

When reading characters printed in black, blue, red, yellow, etc. are dropout colors. These visible light colors not only reflect their respective visible light, but also reflect infrared light well, so they reflect at roughly the same level of intensity as white. That's why it has a dropout collar.

In the case of barcodes, they are sometimes printed in black,
It is often printed in the same color as the product's box or bag. There are many barcodes printed in red, blue, and yellow.

Optical readers configured to read black text cannot read barcodes printed in color.

This does not mean that barcodes printed in color cannot be read. Of course, it is also possible to read barcodes printed in color.

However, in devices that read color barcodes, the colors do not become dropout colors. In this case, even when reading characters, the color does not become a dropout color, so the characters cannot be read.

There is no problem if both the text and barcode are printed in black. However, in cases where the barcode is printed in the same color as the product's box or bag, it is not possible to read both the characters and the barcode.

OO Purpose It is an object of the present invention to provide an optical reading device that can correctly read both characters and barcodes even when the characters and barcodes are printed in different colors.

(3) Configuration In the present invention, one reading system consisting of a lens system and an image sensor is provided for each character and barcode. Instead of using a single reading system, two reading systems are provided.

Those that read characters are called character readers. The system that reads barcodes is called a barcode reading system.

In each reading system, an image of a character or a barcode is formed on an image sensor by a lens system.

Furthermore, there is a light source that illuminates the medium to be read, and this is a common light source for characters and barcodes.

The character reading system and the barcode reading system are designed to have different wavelength ranges of light incident on the image sensor.

An optical filter that allows only light of a specific wavelength to pass is installed between the image sensor and the medium to be read, either in both of the above-mentioned reading systems or only in the barcode reading system.

However, when optical filters are loaded in both reading systems, the optical filters are used to allow different wavelengths to pass through.

A configuration example of the present invention in which an optical filter is loaded only in the barcode reading system will be explained with reference to FIG.

Paper 1 has characters and a barcode written on it. This is an example of what was previously referred to as a medium to be read.

The hand scanner 2 is held and operated by hand, and by applying it to the paper 1, it is possible to read characters and the like.

The hand scanner 2 includes a light source 3.4, a reflecting mirror 5.6, an optical filter 7, a lens system 8.9, and an image sensor 10.1.
1. Built-in binarization circuit 12.13.

There are two systems of exactly the same type. Of these, reflected light 5, lens system 8, image sensor 10, binarization circuit 1
2 is for reading the characters written on the paper.

The output of the character reading system binarization circuit 12 is sent to the character identification circuit 14.
connected to.

The light irradiated onto the paper 1 from the light source 3.4 is reflected by the paper 1. On the other hand, the reflected light passes through a reflecting mirror 5 and a lens system 8,
An image is formed on the image sensor 10.

A reflecting mirror 6, an optical filter 7, a lens system 9, an image sensor 11, and a binarization circuit 13 are used to read barcodes printed on paper. This constitutes a barcode reading system.

The output of the barcode reading system binarization circuit 13 is input to the barcode identification circuit 15.

A portion of the reflected light from the paper 1 passes through a reflecting mirror 6, an optical filter 7, and a lens system 9, and forms an image on an image sensor 11.

The reflecting mirror 5.6 directs the light of different optical paths 17.18 to the optical axis 27 of the character reading system and the optical axis 28 of the barcode reading system, respectively.
reflect to.

The optical filter 7 is a filter that passes only light of a specific wavelength or wavelength range. Do not install this optical filter 7 only in the barcode reading system. Only light in a specific wavelength range reaches the image sensor 11 of the barcode reading system.

An image sensor is a device in which a large number of unit elements that can change the intensity of light into the intensity of an electrical signal are arranged in a two-dimensional or two-dimensional manner. A unit element defines the minimum unit (pixel) of an image. The amount of light that enters a unit element is converted into an electrical signal (charge, voltage, etc.) proportional to this.The electrical signal is obtained for each unit element.The binarization process by the binarization circuit is also performed for each unit element. is performed on the output of

The image sensor 10.11 used here is a two-dimensional image sensor in which a large number of unit elements are provided vertically and horizontally.

The character reading image sensor 10 is an image sensor for character identification that has a field of view that images one or more lines of characters written on the paper 1 at once.

The barcode reading image sensor 11 is a barcode image sensor that has a field of view that images the entire width of the barcode written on the paper 1.

The binarization circuit 12.13 converts the electrical output signal of each unit element of the image sensor 10.11 into a binarization signal, and distinguishes between a character area and a background area.

The character recognition circuit 14 is located outside the hand scanner 2. This process processes the output signal of the binarization circuit 12 to identify characters.

Character identification methods are well known. The characters to be read here are a limited number of characters such as numbers and alphabets. The basic principle is to store the Bakuns of these characters in a memory, compare them with the output of the binarization circuit, and search for Bakuns with matching characteristics to identify all the characters.

The barcode identification circuit 15 processes the output signal of the binarization circuit 13 of the barcode reading system to identify barcodes. There are many known methods of barcode identification. Since barcodes express information by distinguishing between thick and thin bars and by spacing, it is generally easier to identify than characters.

The outputs of the character identification circuit 14 and barcode identification circuit 15 are input to a selection circuit 16. Characters and barcodes are often written in parallel, and both should represent the same information. However, both are not necessarily read correctly.

The selection circuit 16 judges all the identification results of the character identification circuit 14 and the barcode identification circuit 15, selects the correct one, and outputs it as the final result.

The reflecting mirror 5.6 is provided because the hand scanner 2 has an L-shaped bend and the optical path needs to be bent accordingly.

Depending on the shape of the hand scanner, it is also possible to adopt a straight optical path that does not bend. In such a case, a reflector is not necessary.

(b) Function In such an optical reading device, the reflected light of the light irradiated on characters and barcodes is reflected by the respective lens systems.
An image is formed on each image sensor. An image sensor converts the strength of light into the strength of electrical signals.

Image sensors have a peak sensitivity in near-infrared.

Colors such as blue, red, and yellow have a lot of reflection in the near-infrared region, so they are almost the same as white paper. These colors are not detected. It has a dropout color. Since the character reading system does not have an optical filter, these colors become dropout colors. Product packaging is often in these colors, but since it is a dropout color, it does not affect the ability to read text. Since the letters are written in black, there is very little reflection. Black text, white background, and color can be clearly distinguished.

The barcode reading system has an optical filter 7 interposed therein.

This allows only certain wavelengths of light to pass through.

To make sure that the color in which the barcode is printed is a color that has a peak at a location other than the wavelength. Then, the reflected light of the barcode cannot pass through this optical filter 7. Since almost no reflected light from the barcode enters the image sensor 11, it becomes possible to distinguish between the barcode and the background area. In other words,
Be able to read barcodes.

In other words, if an optical filter passes only light of wavelengths well, the color corresponding to the wavelength becomes a dropout color because the amount of reflected light increases. Colors with peaks other than A are treated in the same way as those written on a black background, so they can be read.

(e) Other configuration examples FIG. 2 shows another configuration example of the present invention in which two optical filters 7.19 are provided in front of each image sensor 11.10.

A new optical filter 19 has been added to the character reading system. However, the optical filters 7 and 19 have different passing wavelengths.

Regarding the selection of the optical filter 7 for the barcode reading system,
This is exactly as explained in the example. Choose an optical filter that does not allow the color of the barcode to pass through.

The light reflected from the barcode becomes weaker and can be read.

If an optical filter is also included in the character reading system, the range of characters that can be read can be expanded.

Let us assume that text is printed in color and that colors are also used for product packaging. Let the former color be tΣ, and the latter color be A. The optical filter should be one that allows Ai to pass through and Σ to pass through. By using a dropout color for the packaging, the characters can be read without error.

Effects The optical reading device according to the present invention is a character reading system in which characters describing product codes, product prices, etc., and bar codes are provided with optical filters that are independently provided to allow light of different wavelengths to pass through. , and will be read by a barcode reading system. Therefore, the colors of readable characters and barcodes can be arbitrarily set for each character doper code.

An optical reading device with excellent mechanical properties can be realized.

Many dropout colors are available for text reading. Moreover, it can also read barcodes written in color.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an optical reading device of the present invention. FIG. 2 is another configuration diagram of the optical reading device of the present invention. 1...Paper 2...Hand scanner 3.4...Light source 5.6...Reflector 7...Optical filter 8.9...Lens system 10.11...Image sensor 12 .13...Binarization circuit 14...Character identification circuit 15...Barcode section]Selection circuit 16...Selection circuit Inventor: Nakazawa
Atsushi: Tongue knee and 1 gate

Claims (1)

[Claims] Light sources 3 and 4 that illuminate the medium 1 to be read, an image sensor 10 for reading characters that scans the characters written on the medium 1 to be read, and images of the characters written on the medium 1 to be read. A character reading system consisting of a lens system 8 that forms an image on a character reading image sensor 10, and a character reading binarization circuit 12 that binarizes the output electrical signal of the image sensor 10 depending on the strength of the signal; An image sensor 11 for reading a barcode that scans the barcode written on the medium 1 to be read, and a lens that forms an image of the barcode written on the medium 1 to be read on the image sensor 11 for reading the barcode. A hand scanner that operates a barcode reading system in the hand, which includes a barcode reading system 9 and a barcode reading binarization circuit 13 that binarizes the output electric signal of the image sensor 11 depending on the strength of the signal. 2, and an optical filter 7 that allows only light of a specific wavelength to pass through the optical path of the barcode reading system, or an optical filter 7 that passes only light of a specific wavelength in the optical path of the barcode reading system and the optical path of the character reading system. An optical reader characterized in that wavelength optical filters 7 and 19 are provided respectively.