JPH0431436B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Industrial Application Field The present invention relates to a hand-held optical reading device that optically reads characters and barcodes.

(2) Conventional technologies and their problems Conventionally, there are hand scan type OCRs and barcode readers. A conventional hand-held OCR is described, for example, in Japanese Patent Application Laid-Open No. 16133/1983. Figure 4 shows an example of a conventional handheld OCR.

Characters are read by holding a hand scanner 21 in a hand 22 and moving it over a paper 23.

A light source 24 illuminates the paper 23 and sends the reflected light to the image sensor 26 via a lens system 25.
to form an image. The output signal of the image sensor 26 is amplified by the amplifier circuit 27, and converted to "white" by the binarization circuit 28.
After the paper is divided into two values, ``black'' (paper) and ``black'' (characters), a recognition circuit 29 identifies the characters. Also,
A device for reading both characters and bar codes is described in, for example, Japanese Patent Laid-Open No. 59-81766, and its configuration is shown in FIG.

21 to 29 are the same as those in FIG. 4, so their explanation will be omitted. There is an identification circuit 30 that identifies characters in an identification circuit 29 and identifies barcodes from the output signal of the binarization circuit 28. Based on the identification results sent from the identification circuits 29 and 30, a selection circuit 31 selects the correct one. This is output as a reading result.

For character identification, any resolution that can detect the line width is sufficient, so the dimension corresponding to the line width may be one pixel. However, in the case of barcode identification,
If one pixel corresponds to a narrow bar width, the bar width cannot be distinguished. This relationship and corresponding means will be explained using FIG. 4. The bar 32 has a width a, and the bar 33 has a width b, and now b=2a.

1 of the image sensors 34 shown in FIG.
The pixel is set to be the same as a of the thin bar 32, and the threshold value for binarization is set to 50%. When scanning at the position shown in Figure 6,
In bar 32, two pixel columns in cells 35 and 36 are “black”
Therefore, in bar 33, the two pixel columns of cells 37 and 38 are "black", so even though the bar widths of bar 32 and bar 33 are actually twice as different, the number of "black" pixels after scanning is are the same, bar 32 and bar 3
The bar width will be treated as the same as 3. Therefore, the barcode cannot be identified.

On the other hand, if the pixel size of the image sensor is made smaller to obtain a resolution two to four times that of a thin bar (line width 1/4 mm), an excessive amount of information will be obtained when identifying characters.

Character identification involves preparing various basic patterns in advance and identifying characters by repeatedly comparing the obtained patterns with the basic patterns. /3
Although it is sufficient to be able to detect 1/2mm), if an excessive amount of information is obtained, the following problems will occur in processing.

() Since the amount of basic patterns must be increased according to the amount of input information, a huge amount of storage capacity is required.

() Since the number of patterns of input information increases with the amount of information, the decision algorithm becomes complex and requires a huge amount of time to develop.

() For the same reason, the processing time required to reach character recognition is also enormous.

Furthermore, there may be problems with image sensor design. That is, due to the nature of the device, real-time performance is lost unless reading and scanning of one screen of the image sensor is performed within a certain period of time. However, if the pixels of an image sensor are unnecessarily made finer and the number of pixels increases, the reading time per pixel must be increased accordingly.

This poses a major constraint on the image sensor manufacturing process and makes implementation difficult. Therefore, it is necessary to use dense areas for barcodes and sparse areas for characters.

(3) Purpose of the invention The purpose of the present invention is to improve the conventional drawbacks;
An object of the present invention is to provide a hand-held optical reader for reading characters and barcodes that can perform accurate and efficient recognition.

(4) Means and actions for solving problems The configuration of the present invention is shown in FIG.

The image sensor 4 consists of a barcode imaging section with high pixel density and a character imaging section with low pixel density.

A binary signal obtained from the barcode imaging section through the binarization circuit 51 is sent to the barcode identification circuit.A binary signal obtained from the character imaging section through the binarization circuit 52 is sent to the character identification circuit. each will be sent. In reality, either the barcode or the characters are imaged on the image sensor, so the identification results of each identification circuit are sent to the selection circuit to select the correct one.

FIG. 2 shows the operation of the character barcode reading device of the present invention.

FIG. 2 shows a case where characters are imaged on an image sensor. The character imaging section 42 has a size sufficient to image characters. FIG. 2 shows a case in which a barcode is similarly imaged. Since the height of the entire image sensor is smaller than the imaged barcode, the barcode is necessarily imaged also on the barcode identification section.

In the case of a barcode, since the information is the width of the bars or the white areas between the bars, it is sufficient for the barcode identification section to have one line in the horizontal direction, or even if more accurate, two to three lines at most. In addition, it is necessary to make the pixel density of the barcode identification part finer than that of the character imaging part, as shown in Figure 2, because two bars with different line widths cannot actually be distinguished by the pixel density of the character imaging part. , it is clear from the fact that they become lines of the same width.

(5) Embodiment An embodiment of the present invention will be described based on FIG. 3.

An embodiment of the image sensor used in the present invention is shown in FIG. The top two lines are for barcode imaging, and the bottom 50 lines are for character imaging. The pixel density is 0.05mm for barcodes and 0.1mm for characters, so the overall height is
It becomes 10.2mm.

Additionally, in the horizontal direction, there are 800 columns for barcodes and 400 columns for characters.
Since the rows are lined up and the density is the same both vertically and horizontally, the total width is 40mm.

Using this image sensor, as shown in Figure 3, if an optical system is constructed to image barcodes and characters on a paper surface with a magnification of 1/2, the pixel density (resolution) on the paper surface will be the same as that for barcodes. 0.1mm, 0.2 for text
mm, and the field of view is 10.2 mm x 80 mm.

The height of the barcode is approximately 18mm or more, so
The field of view height of 10.2mm is always included in this range, and the barcode can be reliably imaged on the barcode imaging section. Also, the total width of the barcode row is 0.66mm
(Maximum module width) x 113 (number of modules) = 74.58
mm, and the total width of the character string is 2.54 mm (standard character pitch) x 23 (maximum number of characters) = 58.4 mm or less, so it all fits within the field of view.

By using this image sensor and optical system, a necessary and sufficient character and barcode reading device can be realized.

(6) Effects of the Invention According to the present invention, there is provided a barcode imaging section with a high pixel density that has sufficient resolution for the width of the narrowest bar of a barcode for barcode identification, and a barcode imaging section that is necessary for character identification. Since an image sensor composed of a character imaging section with sufficient resolution and a slightly low pixel density is used, a necessary and sufficient character/barcode reading device is possible.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of the character/barcode reading device of the present invention, Fig. 2 is a diagram showing its operation, and Fig. 3 is an image sensor used as an embodiment of the present invention. A diagram to show,
Figure 4 is a diagram showing a conventional handheld OCR.
FIG. 5 is a diagram showing another conventional hand-held OCR, and FIG. 6 is a diagram showing a conventionally used image sensor. In the figure, 41 is a barcode imaging section, and 42 is a character imaging section.

Claims (1)

[Claims] 1. Regarding the width of the narrowest bar of a barcode for barcode identification in a hand-held optical reader that optically reads characters and barcodes using an image sensor consisting of a plurality of photoelectric conversion elements. A barcode imaging unit with high pixel density and sufficient resolution;
A character/barcode reading device characterized by using an image sensor composed of a character imaging section with a slightly low pixel density and having sufficient resolution necessary for character identification. 2. The character/barcode according to claim 1, wherein the barcode imaging part of the image sensor used is composed of one or several lines of a line sensor, each line of which consists of several hundred or more pixels. reader. 3. Characters according to claim 1, characterized in that the character imaging section of the image sensor used has a size sufficient to fit at least one line of character strings on a price tag, etc. into the field of view.・Barcode reader. 4. The character/barcode reading device according to claim 1, wherein the character imaging section of the image sensor used has a field of view in the height direction that is smaller than the minimum barcode height. 5. Characters and characters according to claim 1, characterized in that the total height of the image sensor used is smaller than the field of view of the entire height of the barcode.
Barcode reader. 6 The binary signal obtained from the barcode imaging section is sent to the barcode identification circuit, the binary signal obtained from the character imaging section is sent to the character identification circuit, the identification results of both identification circuits are sent to the selection circuit, and the correct 2. The character/barcode reading device according to claim 1, wherein the character/barcode reading device selects one of the following. 7 The binary signal obtained from the barcode imaging section is sent to the barcode identification circuit, and the binary signal obtained from the character imaging section is sent to the character identification circuit. The character/barcode identification device according to claim 1, further comprising a selection circuit that adopts any of the identification results.