JPS62166478A - Optical reader - Google Patents

Abstract

PURPOSE:To read optical information accurately by arranging plural photocells on a read sensor and providing a correcting circuit which varies the light intensity of a light source body according to the illuminance of photodetection of those photocells. CONSTITUTION:When reflected light from a label 21 forms an image on a read sensor 30, the light strikes on photocells 34. The cells 34 sense illuminance at their parts and send it to the correcting circuit 35. The circuit 35 amplifies signals from the cells 34 by an amplifier 36 and a current control circuit 37 varies the light intensity of a diode 25 so that the respective signals have the same value. Consequently, an error in the illuminace of the light forming the image on the sensor 30 is due to a difference in optical path length among the respective parts is corrected and the reflected light from the label 21 strikes on any part of the sensor 30 with uniform illuminance. Said correction is made and then a bar code 22 is read by a photoelectric elements 32, so that the information of the bar code is accurately read.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical reading device that optically reads information in characters and patterns.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of an optical reading device that reads barcodes as optical information will be described with reference to FIGS. 4 and 5. A reading section 4 is provided that brings a reading window 3 at the leading end into contact with a barcode 2 printed on the label 1. In this reading section 4, light from a plurality of light sources 5 arranged in a row along the barcode arrangement direction is amplified by an irradiation lens 6, and a reading window 3
The label 1 located at is irradiated. Then, the light is reflected by the label 1 to become reflected light, which is bent by the plane mirror 7 and condensed by the lens 8 and the aperture section 9, and is imaged on the reading sensor 10. Here, the details of the reading sensor 10 include a plurality of light receiving elements 12 formed on a substrate 11, and terminals 13 connected to each of these light receiving elements 12 provided at both ends of the substrate 11. . Also, each terminal 1
3 is connected to a signal recognition circuit (not shown).

Thus, the information of the barcode 2 printed on the label 1 is optically given to the reading sensor 10.

In the reading sensor 10, each light receiving element 12 converts the information into a signal and transmits it to a signal recognition circuit, where the information of the barcode 2 is optically read.

Problems to be Solved by the Invention The reflected light from the label 1 must be focused once and then imaged on the reading sensor 10. Therefore, there is a difference in the optical path length between the reflected light from the center portion of the label 1 and the reflected light from both end portions until reaching the reading sensor 10.
The brightness of reflected light is inconsistent. On the side, read sensor 10
In this case, the illuminance of the light received by each light-receiving element 12 is uneven, and the magnitude of the output signal becomes unstable, making it impossible to accurately recognize information.

The present invention has been made in view of these points, and an object of the present invention is to obtain an optical reading device that can accurately read optical information.

Means for Solving the Problems The present invention arranges a plurality of photocells on a reading sensor, and adjusts the luminous intensity of each of the plurality of light sources that irradiate optical information to the illuminance received by the photocells. A correction circuit was installed to change the value accordingly.

As for the optical information imaged on the reading sensor, the brightness of each portion is detected by each photocell. At this time, if each photocell detects a deviation in brightness in each part, the correction circuit corrects the luminous intensity of the light source.

As a result, the brightness of the optical information imaged on the reading sensor 2 becomes uniform in all parts, and the optical information can be read accurately.

Embodiment of the Invention An embodiment of the present invention will be described with reference to FIGS. 1 to 3. A housing-like case 20 with a bent tip is provided. A reading window 23 is formed at the leading end of the case 20 and is brought into contact with a barcode 22 printed on a label 21. Also, inside the case 20 is a reading window 23.
A light source section 24 that emits light in a direction is provided. Here, this light source section 24 includes a plurality of light emitting diodes 25 arranged along the direction in which the barcodes 22 are arranged, and an irradiation lens 2 that amplifies the light of these light emitting diodes 25.
6 and more. Inside the case 20, a plane mirror 27 is disposed at the bent portion, a lens 28 and a diaphragm portion 29 at the middle portion, and a reading sensor 30 at the rear end. The plane mirror 27 is arranged at a position to receive the reflected light emitted from the light source section 24 and reflected by the label 21, and to bend the reflected light toward the rear end of the case 20. Further, the lens 28 and the aperture section 29
is arranged at a position where it condenses the reflected light from the plane mirror 27 and forms an image on the reading sensor 30.

Here, details of the reading sensor 30 will be explained.

A plurality of light receiving elements 32 are formed on the substrate 31, and a plurality of terminals 33 connected to each of these light receiving elements 32 are provided at both ends of the substrate 31. These terminals 33 are connected as sensor outputs to a sensor signal recognition circuit (not shown). Further, on the substrate 31, a plurality of photocells 34 are arranged in a row in the vicinity of the light receiving elements 32 along the arrangement direction thereof. The number of these photocells 34 corresponds to the number of light emitting diodes 25, and these photocells 34 and the light emitting diodes 2 to 5 are connected via a correction circuit 35 in a one-to-one correspondence. Note that the correction circuit 35 includes an amplifier circuit 36 and a current control circuit 37.

In such a configuration, the light irradiated from the light source section 24 is reflected from the label 21 including the information of the barcode 22, is bent by the plane mirror 27, is focused by the lens 28 and the aperture section 29, and is focused on the reading sensor. Reaching maturity at 30. In the reading sensor 30, each light receiving element 32 senses the information of the barcode 22, outputs it, and transmits it to the sensor signal recognition circuit.

Here, the information of the barcode 22 is read.

On the other hand, in reality, the light intensity of each light emitting diode 25 is corrected prior to reading the information of the barcode 22. That is, when the reflected light from the label 21 forms an image on the reading sensor 30, this light also hits the photocell 34. Each photocell 34 then senses the illuminance in its respective portion and transmits this to the correction circuit 35. In the correction circuit 35, the signal from each photocell 34 is amplified by an amplifier circuit 36, and the luminous intensity of each light emitting diode 25 is varied by a current control circuit 37 so that each signal has the same value. As a result, the illuminance error of each part of the reading sensor 30 caused by the difference in the optical path length of each part is corrected regarding the illuminance of the light that forms an image on the reading sensor 30. 21 reflected light forms an image.

After making such corrections, if the information of the barcode 22 is read by the photoelectric element 32, the information of the barcode can be read accurately.

Effects of the Invention The present invention provides a modification in which a plurality of photocells are arranged on a reading sensor, and the luminous intensity of each of the plurality of light sources that irradiates optical information is varied according to the illuminance received by the photocell. Since the circuit is provided, the light containing optical information that is imaged on the reading sensor becomes uniform in any part of the reading sensor by modifying the luminous intensity of the light source by the correction circuit, so that the optical information formed by the reading sensor becomes uniform. This has the advantage that reading can be made more accurate and misreading and reading errors can be eliminated.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the arrangement and connection of an optical system according to an embodiment of the present invention, FIG. 2 is an overall longitudinal sectional side view, and FIG.
The figure is a perspective view of a reading sensor, FIG. 4 is an overall vertical side view showing an example of the conventional technology, and FIG. 5 is a perspective view of the reading sensor. 22... Barcode (optical information), 25... Light emitting diode (light source), 30... Reading sensor, 32.
...Photocell, 35... Modified circuit application Person: Tokyo Electric Co., Ltd.

Claims (1)

[Claims] A plurality of light source bodies that irradiate light onto one-dimensional optical information are provided, a reading sensor is provided that receives reflected light emitted from these light source bodies and reflected by the optical information, and a plurality of light sources are provided on the reading sensor. What is claimed is: 1. An optical reading device comprising: a plurality of photocells, and a correction circuit for varying the luminous intensity of each of the light sources according to the illuminance received by these photocells.