JPS6086687A - Transmission type photosensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an optical sensor used in a paper sheet discrimination device or the like.

fb) Background of the technology In devices for automatically discriminating paper sheets such as banknotes and other valuable coupons, or determining their authenticity, in addition to the dimensions of the paper sheets, Various patterns (characters, figures) that have been formed are detected as discrimination targets. A magnetic method and an optical method are used to detect the pattern.

This optical method also includes various methods, such as using visible light, ultraviolet light, infrared light, etc., and detecting reflected light or transmitted light from the test pattern. These methods are used in combination -0 depending on the required accuracy of discrimination.

(1.1 Prior Art and Problems) The present invention relates to a transmission type optical sensor used in a method of detecting light transmitted through paper sheets to be inspected, and in particular, the present invention relates to a transmission type optical sensor that is used in a method for detecting light transmitted through paper sheets to be inspected. This article discloses an improvement in the structure of the lens barrel formed in the boulder portion of the sensor.

The outline of the structure of the conventional transmission type optical sensor used for the purpose mentioned above is shown in Figure 1. For example, the light emitted from the light source l of a light emitting diode However, for example, the paper hard object 2 to be tested, such as a banknote, is shot 11.6 times,
A part of the Il&riL light transmitted through the test paper sheet 2 is
For example, the light enters a light receiver 3 such as a photodiode.

The light source 1 and the light receiver 3 are fixed in cylindrical barrels 51 and 52 provided in the holder parts 41 and 42. The holder parts 41 and 42 are usually manufactured separately, but are combined with a cutout section through which the paper sheet 2 to be inspected passes.

In the conventional transmission type optical sensor having the above structure, the light emitted from the light source is cut off by the inner wall of the cylindrical lens barrel 51, and a part of the transmitted and scattered light from the paper sheet 2 to be tested is absorbed by the cylindrical lens barrel. 52, the light irradiation efficiency on the paper sheet 2 to be inspected and the signal light collection efficiency by the light receiver 3 are low. There have been problems such as being susceptible to mounting position errors or positional fluctuations while the paper sheet 2 to be inspected is traveling. As a result, in order to ensure sufficient detection sensitivity and discrimination reliability, the signal detection processing circuit has to be complicated and expensive.

(d) Purpose of the Invention The present invention improves the light irradiation efficiency and light collection efficiency using a relatively simple method, thereby making it possible to eliminate the drawbacks caused by the conventional transmission type optical sensor. With the goal.

(e1 Structure of the Invention The present invention consists of a light source, a light receiver, and a holder portion for holding these and blocking external light. A transmission-type optical sensor that detects changes in the amount of transmitted light is attached to the inner wall surface of the lens barrel formed in the boulder part, and the aperture increases toward the traveling position of the paper sheet on both sides. It is characterized by being slanted.

(f) Embodiments of the Invention Below, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same parts as in FIG. 1 are designated by the same reference numerals.

FIG. 2 shows a schematic structure of a transmission type optical sensor 9 according to the present invention, in which a boulder part 41 houses a light source 1 and a light receiver 3.
and 42, the aperture becomes larger as it moves from both ends, that is, from the installation part of the light source 1 and the light receiver 3 toward the traveling position of the paper sheet 2 to be inspected. The lens barrels 61 and 62 are inclined and conical.

By adopting the structure as shown in the figure, even when a comparatively low-directivity light emitting diode (LED) is used as the light source 1 and a relatively wide area of the paper sheet 2 to be tested is irradiated, a sufficient amount of light can be transmitted and scattered. Light can enter the light receiver 3, and detection sensitivity is improved. Furthermore, even if the paper sheet 2 to be inspected changes its position in the optical axis direction, the light collection efficiency of the transmitted and scattered light is maintained constant, so the fluctuation in detection sensitivity is reduced. . Furthermore, fluctuations in irradiation efficiency or light collection efficiency due to optical axis misalignment due to mounting errors between the light source 1 and the light receiver 3 during assembly or maintenance are also reduced.

The degree of inclination given to the inner wall surface of each of the conical lens barrels 61 and 62 is determined by taking into consideration the directivity of the light source 1 (for example, an LED), the diameter of the irradiated area on the paper sheet 2 to be inspected, etc. It will be done. However, the inclination angle φ on the conical lens barrel 61 side is equal to the divergence angle (optical axis reference) of the emitted light from the light source 1, and the distance between the traveling center position of the light source 1 and the paper sheet 2 to be inspected at this time is The distance Ll is determined so that the diameter of the area to be irradiated on the paper sheet 2 to be inspected by the emitted light having the divergence angle (φ) becomes a predetermined value.

In addition, the inclination angle θ on the conical lens barrel 62 side is
The distance 1i+1L2 between the traveling center position and the light receiver 3 and t'LD of the irradiated area are determined.

Considering the maximum amount of variation in the running position of the paper sheet 2 to be inspected, that is, the distance δ between the running center position and the open CI surface of the conical lens barrel 62, (L2-δ) tan θ= (Ll+δ) tan
φ Therefore, θ−tan' (D (Ll+δ) / 21.1
(1,2-δ)].

Note that the inner wall surfaces of the conical lens barrels 61 and 62 are surface-treated to have low reflectance in order to prevent external light disturbance.

In the transmission type optical sensor having the above structure, 1) the amount of light emitted from the light source is effectively used, the efficiency of collecting the signal light by the light receiver is improved, and the position change due to the movement of the test IC leaves and the light source And the signal light is zero due to the position error of the receiver! Li degree fluctuations are reduced.

(g1 Effects of the Invention According to the present invention, the irradiation efficiency and light collection efficiency in the transmission type optical sensor are improved, and the fluctuations in the signal light are reduced, so it is easy to improve the reliability of the paper sheet discrimination device. This has the effect of making it possible to reduce the cost of the paper sheet discriminating device.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams showing the schematic structure of a conventional transmission type optical sensor and a transmission type optical sensor according to the present invention, respectively. In the figure, 1 is a light source, 2 is a paper sheet to be inspected, 3 is a light receiver,
41 and 42 are holder parts, 51 and 52 are cylindrical lens barrels, and 61 and 62 are conical lens barrels. ¥1 river 1 fu2 drawings

Claims (1)

[Claims] It consists of a light source, a light receiver, and a holder part that holds them and blocks external light, and detects changes in the amount of light that passes through the paper sheet to be inspected as it travels between the light source and the light receiver. A transmission type optical sensor is characterized in that the inner wall surface of the lens barrel formed in the holder portion is inclined so that the diameter increases from both ends toward the traveling position of the paper sheet to be inspected. Transmissive optical sensor.