JPS63191288A - Optical information reader - Google Patents

Abstract

PURPOSE:To read information with high stability even with a bar code recorded on a curved surface by setting the illuminating directions of the illumination devices set at both sides of an array of plural illumination devices at the front side and setting both illumination devices before other ones. CONSTITUTION:The secondary illumination devices 12 and 13 are set at both sides of the main illumination devices 11. Each of these illumination devices contains an LED and a condenser lens and the illumination beams of these devices are condensed slightly inside. In other words, the illumination beams of devices 12 and 13 are turned inside so that the curved bar codes can be read and furthermore these devices 12 and 13 are set at positions closer to the bar code than the devices 11. Thus a curved bar code can be read with high accuracy owing to the synergistic effect of the structures of devices 12 and 13 and the lighting time control of devices 11, 12 and 13 respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical information reading device that reads optically recorded information, and in particular, to an optical information reading device that improves the reading accuracy.

[Conventional technology]

Conventionally, as such an optical information reading device, one disclosed in Japanese Patent Application Laid-Open No. 190673/1983 has been known. This one uses an electrical signal from a reading sensor.
A change in the amount of light in the image is detected, and the width of the illumination pulse by the illumination means is changed in accordance with this change in the amount of light. This results in
A stable electrical signal can be obtained from the reading sensor, and stable reading can be performed. In this way, the illumination means irradiates uniform light onto the entire information to be read and adjusts the amount of light.

[Problem that the invention seeks to solve]

However, in the conventional technology in which the illumination means irradiates uniform light over the entire information to be read, when the information to be read is curved, the illuminance of the information to be read decreases toward both ends of the curved surface. descend. This has caused a problem in that the reading accuracy is significantly reduced.

The present invention was made in view of these problems, and its purpose is to provide optical information that can be read stably even when barcodes are recorded on curved surfaces. The purpose of the present invention is to provide a reading device.

[Means for solving problems]

Therefore, in order to achieve the above-mentioned object, the present invention illuminates optically recorded information to be read, as shown in FIG.
a plurality of illumination devices arranged in a row; an optical system that forms an image of the information to be read at a predetermined position; and a charging converter that is provided at the predetermined position and converts the image into an electrical signal; In the optical information reading device, the optical information reading device includes a signal processing means for reading the information to be read based on the electrical signal from the photoelectric converter. A technical measure is adopted in which the lighting device is positioned in front of other lighting devices.

[Effect]

In the present invention having the above-described configuration, among the plurality of lighting devices arranged in a row, the lighting devices on both sides are arranged further forward, so that the barcode is recorded in a curved manner. In this case, both sides are illuminated from a closer position. This compensates for the illuminance on both sides of the curved barcode.

〔Effect of the invention〕

With the configuration and operation of the present invention described above, in the optical information reading device according to the present invention, the illuminance on both sides of the curved information to be read is compensated for, so that the curved information to be read can be read with high accuracy.

〔Example〕

Examples to which the present invention is applied will be described below.

First, the configuration of an embodiment in which the present invention is applied to a barcode reading device will be described based on the drawings.

FIG. 2 is a perspective view showing the configuration of the optical path portion of this embodiment.

1 is a label with a barcode printed on it, and 2 is a barcode.

Reference numeral 10 denotes an optical reading section, which includes the following components in a case (not shown).

11 is a main illumination device, which consists of four high-intensity red light emitting diodes (LEDs) 11a and a condensing lens 11b. 12.13 is a sub-lighting device, and main lighting device 1
Each is provided on both sides of 1. These are each equipped with an LED and a condensing lens, and their illumination light is condensed slightly inward.

14 is a reflecting mirror, 15 is an imaging lens, and 16 is a diaphragm, and these constitute an optical system. 17 is an image sensor in which photo elements are arranged in a straight line. This example has a resolution of 2048 bits, and the LED l
Those having high spectral sensitivity near the emission wavelengths of la, 12a, and 13a were used.

Then, using the above-mentioned optical system, the image of barcode 2 is
An image is formed on this image sensor 17.

FIG. 3 is a block configuration diagram showing the configuration of the electrical control section of this embodiment.

In this embodiment, the electrical control section 20 is constructed separately from the optical reading section 10 shown in FIG. 2, and is connected to the optical reading section 10 by an appropriate cable.

21 is an amplifier circuit, 22 is a sample and hold circuit, 23 is a binarization circuit, 24 is a counter circuit, and 25 is a microcomputer. With these configurations, the barcode 2 is read and the barcoded information is output from the microcomputer 25.

26 is a video amplitude detection circuit, 27 is a microcomputer, and 28a and 28b are drive circuits for the LEDs 12a and 13a. These are LEDIla, 12a, 13a
Adjust the lighting time.

And 29 is a clock oscillator.

Next, the operation of this embodiment will be explained based on the drawings.

FIG. 4 is a time chart showing signal waveforms of each electrical control section shown in FIG. 3.

Reading start signal Sl output by the microcomputer 25
Each part operates in synchronization with the

Normally, the microcomputer 27 sends the lighting command S2 at time T+ and the lighting command S3 at time T2 to the drive circuit 28a.
, 28b.

This causes LEDlla to change for a time T, , LEDI2a
, 13a are lit for a time T2. This T1°T2 is predetermined, and is determined so that the amount of exposure light of the image sensor 17 is approximately uniform over the entire reading line L1 when a plane is illuminated.

When the label l is a flat surface, an image of the barcode 2 on the reading line Ll is formed on the image sensor 17. The image sensor 17 sequentially outputs a signal corresponding to the charge of each photo element accumulated during the exposure time of time T3. This output is amplified by an amplifier circuit 21, and a sample hold circuit 22
The signal is sampled and held and shaped into a video signal S4 corresponding to the black and white bars of barcode 2. In addition, the fourth
The figure shows the peak value of the sampled and held signal, that is, the signal level of the white bar.

Further, this video signal S4 is shaped into a binary signal by a binarization circuit 23, and the 20-binarized signal is counted by a clock signal by a counter circuit 24 as a width corresponding to a black bar and a white bar. The count value corresponding to each bar is stored in the RAM of the microcomputer 25 as bar data.

On the other hand, the video amplitude detection circuit 26 divides the clock signal to generate a sample clock S5, samples and holds the peak value of the video signal S4 at the falling edge of the sample clock S5, and outputs a distribution signal S6. . In this embodiment, the video signal S2 is divided into three parts, and the peak value of each part of the video signal is used as the distribution signal S6.

In a series of operations based on the reading start signal S11 in FIG. 4, the video signal 341 shows a substantially uniform distribution of peak values. When the microcomputer 27 determines that the distribution signal 561 shows a substantially uniform distribution, it outputs a decoding permission signal S7 to the microcomputer 25, and the microcomputer 25 decodes the bar data stored in the RAM in a predetermined manner. Decode with program and ASC
Convert to II code etc. and output.

However, if label 1 is curved as shown in Figure 2,
The reading line is reading line L2 along this curve. Therefore, in the illumination at the above-mentioned time T and time T2, the illuminance decreases toward both ends of the label 1. Since the brightness of the image formed on the image sensor 17 also decreases, exposure becomes insufficient and the video signal S4 also decreases.

This ladder is shown in the reading start signal SL2 in Fig. 4.
This is a series of signal waveforms.

As shown in the figure, the peak value of the video signal S42 decreases toward both ends. Therefore, the distribution signal 362 has a step-like shape, and since the step difference is large, the microcomputer 27 does not output the permission signal S7. And the microcomputer 27 is LE
This illuminance difference is corrected by adjusting the lighting time of Dlla, 12a, and 13a and adjusting the amount of exposure light of the image sensor 17.

That is, T, , Tt are determined so that the distribution of peak values of the video signal S4 is approximately uniform. In the video signal S42 based on the reading start signal S12, a substantially sufficient peak value is obtained at the center C, and the peak value is low at the right side R1 and at the left side. For this reason, the barcode 2 cannot be read correctly, resulting in a reading failure.

Therefore, in the reading start signal S13, the lighting command S2 is set to time TI, and the lighting command S3 is set to time T2'.

As a result, the time during which both ends of the label 1 are illuminated becomes longer, the amount of exposure light of the image sensor 17 increases, and the peak value of the video signal 343 becomes substantially uniform.

When the distribution signal 363 becomes substantially uniform in this way, the microcomputer 27 outputs the permission signal S7, and the microcomputer 25 decodes the barcode 2.

In this way, according to this embodiment, both flat barcodes and curved barcodes can be read.

In addition, in this embodiment, especially for reading curved barcodes, a sub-illumination device is used! ! 12 and 13 are arranged inward, and these are located closer to the barcode than the main illumination device 11.

Due to the synergistic effect of the configuration of the sub-illumination devices 12.13 and the control of the lighting time of these main and 2 sub-illumination devices 11, 12.13, this embodiment can print curved barcodes with sufficient accuracy. It can be read.

In the embodiments described above, each illumination device is arranged with particular consideration to reading curved barcodes.
The auxiliary lighting devices 12 and 13 on both sides are set to have the same lighting time. However, the lighting devices may be arranged in a line and each lighting time may be adjusted separately. In this way, even if a part of the flat label is illuminated by external light, the difference in illuminance due to the external light can be corrected, and the reading accuracy can be improved.

Furthermore, in this example, in order to correct the difference in illuminance, the lighting time of each lighting device was adjusted, and the amount of exposure light of the image sensor was adjusted. However, the illuminance of the information to be read may be adjusted by adjusting the luminance of each illumination device.

Further, in this embodiment, two microcomputers 25 and 27 are provided, one for reading and one for illumination.

However, these functions may be performed by one microcomputer.

Furthermore, the information to be read is not limited to barcodes, but may be various optically stored information such as OCR characters.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram showing the structure of the present invention, FIG. 2 is a perspective view showing the structure of an optical reading section of an embodiment to which the present invention is applied, and FIG. 3 is a block diagram showing the structure of an optical reading section to which the present invention is applied. FIG. 4 is a block diagram showing the configuration of the electric control section, and a time chart showing signal waveforms of each part of the electric control section in an embodiment to which the present invention is applied. Ml... multiple illumination devices, M2... optical system, M3...
...Photoelectric converter, M4...Signal processing means, M5...
Detection means, M6... Light control means, M7... Lighting control means, 1... Label, 2... Barcode, 10...
Optical reading unit, 11... Main illumination device, 12.13...
Sub-illumination device, 11a, 12a, 13a...high brightness red light emitting diode (LED), llb, 12b, 13b...
...Condensing lens, 14...Reflection 61.15...Imaging lens, 16...Aperture, 17...Image sensor, Ll, L2...Reading line, 20...Electricity control unit,
21... Amplification circuit, 22... Sample hold circuit, 23... Binarization circuit, 24... Counter circuit, 2
5...Microcomputer (for reading), 26...
Video amplitude detection circuit, 27... microcomputer (
for lighting), 28a, 28b...drive circuit, 29...
Clock oscillator, GK...clock signal. Figure 1

Claims (1)

[Scope of Claims] A plurality of illumination devices that illuminate optically recorded information to be read and are arranged in a line; an optical system that forms an image of the information to be read at a predetermined position; and the predetermined location. An optical information reading device comprising: a photoelectric converter installed at a position and converting the image into an electric signal; and a signal processing means reading the information to be read based on the electric signal from the photoelectric converter. An optical information reading device characterized in that, among the plurality of illumination devices, the illumination devices on both sides are arranged in front of the other illumination devices with their illumination directions facing forward.