JPS6112313B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical reading device that optically reads code information attached to articles, etc., and particularly relates to a method of controlling a light receiving means provided at the periphery of a scanning window.

Recently, at supermarkets, etc., the price and code of a product are printed on a tag card consisting of spaces and bars, and the printed information is read by scanning the card optically.
sales) system is being put into practical use.

FIG. 1 shows a perspective view of a conventional optical reading device in such a POS system, in which a light beam l output from a light source 1 is transmitted through an electrically driveable reflector plate 2 (for example, a galvano mirror). The reflected light is reflected by a reflecting mirror 4 rotated by a motor 3, and this reflected light beam is scanned onto a fixed reflecting mirror group 5 arranged in a semicircle with the reflecting mirror 4 as the center. The light beam reflected by 5 scans a transparent scanning window 6, scans a bar code affixed to a product 7 placed on the scanning window 6, and detects this reflected light by a light receiving means 8 to detect the above-mentioned. It is designed to read code information.

By the way, since a glass plate or the like is normally used for the scanning window of the above-mentioned optical reading device, the reflected light l' from the fixed mirror group 5 is reflected on the back surface of this reading window and is introduced directly into the light receiving means 8. You will end up being rejected. (See Figure 2) The reflected light from the back surface of this scanning window is normally about 5% of the incident light.
However, the amount of reflected light is quite large compared to the scattered reflected light from the barcode label used as the barcode signal of this optical reading device, and therefore, when this reflected light enters the amplifier via the light receiving means 8, it causes temporary damage. This causes the amplifier to enter the saturation region, making it impossible to detect the scattered reflected light from the barcode label.

Therefore, it is necessary to move the installation location of the light receiving means 8 shown in FIG. 1 back to a position where the light directly reflected from the back surface of the reading window does not enter. However, when the light receiving means 8 is moved back, the absolute amount of light that can be received by the light receiving means decreases, so countermeasures such as increasing the number of light receiving means or improving the performance of the amplifier that amplifies the signal from the light receiving means are taken. becomes necessary.

Therefore, in order to eliminate the above-mentioned problems, the present invention provides a plurality of light receiving means at the periphery of the scanning window, and when any one of the light receiving means detects direct reflection from the back surface of the scanning window, the light receiving means This prohibits the extraction of optical signals from other light receiving means, and attempts to extract optical signals from other light receiving means.

The present invention will be explained in detail below with reference to the drawings.

3 and 4 are diagrams showing one embodiment of the present invention, and FIG. 3 is a diagram showing its configuration. Its operation is the same as that in FIG. 1, but there are multiple The light receiving elements 9 ₁ to 9 _o are provided, and the article 7
It is configured to receive scattered reflected light from the barcode label attached to the barcode label.

FIG. 4 is a diagram showing a specific circuit configuration for carrying out the present invention. In this embodiment, the scattered light from the barcode label attached to the article 7 is transmitted through the light receiving means 9 ₁ to 9 _o and the gate means. The signals are input to amplifiers A ₁ to A _o via 10 ₁ to 10 _o , amplified to a predetermined level, added to the adding means 11, input to the central processing unit 12, and added to the barcode label in a predetermined procedure. Recognize written code information.

By the way, in this device, if the light receiving means 9
When the direct reflected light from the back surface of the scanning window 6 is detected from ₁ , this optical signal is input to the amplifier A ₁ via the light receiving means 9 ₁ and the gate means 10 ₁ , but this amplifier A ₁ is saturated and the state The first input terminal of the detection means 13 notifies the state detection means 13 that the amplifier _A1 is saturated.

When the amplifier _A1 is saturated, the state detection means 13 outputs a low level signal "L" from the first output terminal, prohibits the operation of the gate means ₁₀₁ , and detects the signal input from the gate means ₁₀₁ . The introduction of optical signals from the light receiving means ₉₁ is prohibited.

Therefore, subsequent recognition of the code information written on the barcode label is performed by optical signals from the light receiving means ₉₂ to _9o .

As described above, when direct reflection from the scanning window is detected, the state detection means prohibits the introduction of the optical signal from the light receiving means that detected it, and information is recognized using the optical signals of other light receiving means.

Note that the state detection means 13 includes light receiving means 9 ₁ to 9
When direct reflection from the back surface of the scanning window is not detected in any of the light receiving means o, a high level signal "H" is derived from the output terminals 1 to n, and the gate means 10 _{1 to o}
The light receiving means 91 _{to 9o} are enabled to operate, and the optical signals from the light receiving means 91 to 9o are input to the amplifiers A1 _{to 9o} .

As described above, according to the present invention, when direct reflection on the back surface of the scanning window is detected, the introduction of the optical signal from the light receiving means is prohibited, and the code information on the barcode label is read by the optical signal from the other light receiving means. Because of this recognition, accurate reading operations can always be performed without the influence of direct reflection, making it possible to provide a very useful optical reading device.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing the optical system of a conventional optical reading device, FIG. 2 is a diagram showing the related configuration of the scanning window and light receiving means of the same device, and FIG. 3 is a configuration diagram showing the optical system of the optical reading device of the present invention. 4 are circuit block diagrams showing the light receiving means control component of the same device. 1: Light source, 2: Reflector, 4: Reflector (rotating mirror), 5: Fixed reflector group, 6: Scanning window, 9 ₁ to 9
_o : Light receiving means, 10 ₁ ~ 10 _o : Gate means, A ₁ ~
A _o : amplifier, 11: addition means, 12: central processing unit, 13: state detection means.

Claims (1)

[Claims] 1. Light from a light source is irradiated onto a reflecting plate, and the light from the reflecting plate is irradiated via a rotating mirror onto a group of fixed mirrors arranged semicircularly around the rotating mirror. , the information is recognized by irradiating the reflected light of the fixed mirror group onto an optically readable information carrier attached to an article placed on the scanning window, and receiving the reflected light by a light receiving means. In such an optical reading device, a plurality of light receiving means for receiving the reflected light from the information carrier are installed around the periphery of the scanning window, and the state of the signal from each of these light receiving means is monitored respectively. The state detecting means detects the presence or absence of the light receiving means that has received the reflected light, and based on the state detection of the state detecting means, the extraction of the optical signal from the light receiving means that has directly received the reflected light is prohibited from being transmitted from other light receiving means. An optical reading device characterized in that it extracts.