JPH02244291A - Optical sensor output binarizing system - Google Patents

Abstract

PURPOSE:To make a black/white deciding level suitable, and to decrease read errors by deciding >= three white levels, and deciding black or white using the intermediate value of a decision value as a reference value. CONSTITUTION:When a bar code is read by an optical reader, and a fold 1 or a stain 2 of a medium exists, a sensor output increases or decreases respectively. At such a time, by setting arbitrary measuring points 11 to 13 of a white level, comparing the three levels, and selecting the intermediate value, the reference value suitable for the decision of the black of bar codes 14 to 16 can be set. Thus the white level to be the suitable reference can be obtained, the erroneous read of the bar code, etc., is decreased, and even when there is the fold or stain on the medium, the bar code can be read.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a system for optically reading barcode marks and characters, and particularly to an optical reading system suitable for binary determination of white/black levels.

[Conventional technology]

Conventional optical reading devices detect white level fluctuations due to changes in reflectance due to dirt on the medium or folds on the medium.
It was not possible to set an appropriate white/black judgment level, resulting in incorrect reading. Related devices of this type include Japanese Patent Application Laid-open Nos. 59-5386, 63-16393, and 6
No. 1-199180, No. 62-22638, No. 61-
No. 117675, No. 56-68875, No. 56-67
No. 484, No. 56-44974, No. 55-14097
Examples include No. 4.

[Problem to be solved by the invention]

The conventional optical reading method, which uses peak hold to determine white/black based on the white level, detects creases in the media,
No consideration is given to the rise in the white level due to diffuse reflection of light from the edges of the medium, and the black level continues to drop. In addition, the white/black determination method based on the white level at one point using sampling and hold does not take into account contamination of the medium, and there are problems such as over-reading of the black level and overflowing. 6. Purpose of the present invention The object of the present invention is to solve the problems of the above two methods, and to set an appropriate white/black determination level to reduce misreading even if there are dirt marks, edges, or stains on the medium.

[Means to solve the problem]

The above purpose was achieved by determining the white level at at least three locations and determining white/black using the intermediate value of the determined values as a reference value, instead of the conventional method of peak-holding or sampling-holding the white level. will be accomplished. That is, in this method, the white level is measured at three or more locations and the intermediate value is used as a reference, so that the black/white determination level can be optimized and misreading can be reduced.

[Effect]

FIG. 1 shows the relationship between the sensor output of a medium when a barcode is read by an optical reading blade device. In the present invention, when reading the barcodes 3, 4.5 located in section b of the medium shown in FIG. 1, the white level is measured using the fact that section 0 is the white level. However, there are 1 fold marks on the media on the 0th copy. Broken 2. If there is, the sensor output will increase or decrease, respectively. Here, if arbitrary measurement points of the white level are set to 11, 12, and 13, high, low, and medium levels are obtained, respectively. White level 13 is selected by comparing these three levels and selecting the middle value, which can be used as an appropriate reference value for determining the blackness of barcodes 14, 15, and 16.

In the above example, measurements are taken at three locations, but by increasing the number of measurement points, a more accurate white level can be selected.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. FIG. 2 is a block diagram of an optical reading circuit to which the present invention is applied. The optical sensor 21 is.

Outputs the signal read from the medium. Sampling peak hold circuits 23, 24, and 25 store sensor output levels at timing occurrences with separate arbitrary timing signals from processor 22.

The level comparator 26 compares the levels stored above and sends to the selection circuit 27 a signal designating the peak hold circuit storing the intermediate level. The selection circuit 27 thereby sends the intermediate level value to the comparator 28, which uses this as a reference value and compares it with the output level of the optical sensor 22 to determine the black and white level. In this embodiment, three measurement points are used, but it goes without saying that increasing the number of measurement points allows for more accurate white level measurement. In addition, for misreading abnormalities, the measurement points can be changed using the method described below using the flowchart shown in FIG. 3, and the same effect as equivalently increasing the number of measurement points can be obtained. Select a measurement point and take a reading. The read result is checked for format, etc., and if it is abnormal, a different measurement point from the previous one is calculated and read again.

By this operation, each time re-reading is performed, many white level measurement points can be obtained through measurement addition.

In FIG. 1, the embodiment of the present invention has been described mainly using an analog circuit, but it goes without saying that the present invention can also be applied to a circuit that uses an A-D converter circuit and selects a reference value in combination with a program.

〔Effect of the invention〕

As described above, according to the present invention, the optical sensor output white/
When converting the black level to binary, the reference white level is measured at three or more locations and the middle value of the measured values is selected. Decrease.

(2) Even if there are bending marks on the medium, it can be read.

(3) Even if there is dirt on the medium, it can be read.

There are other effects.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the relationship between a reading medium and the output of an optical sensor according to an embodiment of the present invention, FIG. 2 is a block diagram of an optical reading circuit according to an embodiment of the present invention, and FIG. It is a flowchart of reading by a sensor. 21: Optical sensor, 22: Processor, 23°24.2
5: Sampler peak hold circuit, 26: Level comparator, 27: Selection circuit, 28: Comparator.

Claims (1)

[Claims] 1. A device that uses an optical sensor to read barcodes and characters recorded on a medium, comprising means for storing white levels at a plurality of locations on the medium, and means for comparing the stored values; An optical sensor output binarization method that selects an intermediate value from the results, uses the selected value as a reference value, and performs binarization of white/black levels based on this value.