JPH0438311Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a reflective photo interrupter used, for example, in a copying machine to detect the presence or absence of paper feed.

[Conventional technology]

As shown in FIG. 5, the copying machine is provided with a sensor S at a predetermined position in a paper feed path to detect the presence or absence of copy paper (paper to be detected) A. For this type of sensor, for example, as shown in FIG. 6, two round holes 22 and 23 are arranged side by side in a lamp house 21, and inside the holes there is a light emitting part (infrared LED) 24 and a light receiving part (phototransistor) 25. A reflective photo interrupter 20 is used.

This reflective photo interrupter 20 detects the presence of the paper A to be detected by receiving a part of the diffused reflection when the light emitted from the light emitting part 24 is reflected by the paper A to be detected by the light receiving part 25. , light emitting section 2
A circular irradiation area B21 and a circular detection area B22 are located on the detection target paper passing surface in front of the light receiving section 25 and the light receiving section 25, and a portion thereof (the shaded area) overlaps. The light from the LED that hits this shaded area is most intensely incident on the light receiving section 25.

[The problem that the idea aims to solve]

In such a structure, since the light receiving hole 23 is a round hole, it easily receives ambient light. Furthermore, since the light receiving holes 22 and 23 are round holes, the detected paper A moves from the (-) direction to the (+) direction of the y-axis with respect to the sensor S, as shown in FIG. In this case, when the detected paper A is at a (-) level that does not reach the x-axis, which is the center position of the sensor S, there is a possibility that the detected paper A will be detected as if it had moved to the sensor center position. Furthermore, since the distance between the round holes 22 and 23 for emitting and receiving light is relatively wide, there is a problem in that there is not enough room for short-range detection characteristics as a photo interrupter.

An object of the present invention is to provide a reflective photo interrupter that is less affected by ambient light and can improve short-range detection characteristics and position detection characteristics.

[Means for Solving the Problems] The present invention provides a light emitting opening and a light receiving opening in the lamp house, and the light emitting part and the light receiving part are placed inside the lamp house so that the light emitting part and the light receiving part are connected to the irradiation area and the detection area on the detection paper passing surface. In a reflective photo interrupter arranged so that portions overlap, both openings extend in a direction perpendicular to the moving direction of the detected paper, and slits are arranged adjacent to each other on a straight line along the extending direction. The present invention is characterized in that the detection target paper has a positional relationship that is shifted in the moving direction of the detection target paper.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

Figures 1 to 3 show an embodiment of the present invention, in which a slit-shaped light-emitting opening 2 and a light-receiving opening 3 are provided in a lamp house 1, and a light-emitting part (infrared LED) is installed inside the lamp house 1. 4. Light receiving part (phototransistor)
5 are installed. The positions of both openings 2 and 3 are set so that they are slightly shifted in the direction of movement of the paper to be detected A, with the light-receiving opening 3 being located closer to the front of the center line, and the light-emitting opening 2 being located closer to the rear of the center line. are doing.

In the case of the above structure, the irradiation area B1 and the detection area B on the detection paper passing surface of the light emitting unit 4 and the light receiving unit 5
2 has a rectangular shape as shown in FIGS. 2 and 3, and a portion (hatched portion) thereof overlaps. The light reflected from this overlapping portion is the strongest and enters the light receiving section 5.

Therefore, when the detected paper A moves from the (+) to (-) direction of the y-axis, more reflected light enters the light receiving section 5 from the point where the end surface of the detected paper A reaches the Mf line. , the strongest incidence occurs when it reaches the shaded area. In addition, when the detection paper A moves from the opposite direction, more reflected light enters the light receiving unit 5 from the point where the end surface of the detection paper A reaches the Mr line, and the sunder line Mo (x axis) The strongest incidence occurs when it reaches the shaded area. As a result, the difference in detection position between the scattering reflection object and the specular reflection object becomes small, and the beam width itself becomes narrow, so the position detection characteristics are greatly improved.

In order to improve the position detection characteristics, it is desirable to make the slit width as narrow as possible so that the irradiation area B11 and the detection area B12 are in the same line, as shown in Figure 4, but it is extremely difficult to manufacture a mold for this purpose. ,
Production costs increase. On this point, in this embodiment, by slightly shifting the light emitting and light receiving openings 2 and 3 in the direction of movement of the paper to be detected, it is possible to create a slit of an appropriate size that is easy to manufacture a mold, and a slit with a narrow slit width. I am trying to get the same effect as.

[Effect of idea]

As described above, according to the present invention, since the light receiving opening is formed into a slit shape, the influence of ambient light can be minimized. Furthermore, since the light emitting and light receiving openings are slit-shaped, the position detection characteristics can be improved, and the distance between the two openings can be narrowed, making it possible to provide a margin for short-range detection characteristics. Furthermore, since both openings are slightly shifted in the direction of movement of the paper to be detected, there are advantages in that the position detection characteristics can be improved and mold manufacturing becomes easier.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an embodiment of the reflective photo interrupter according to the present invention, Fig. 2 is a front view of the detection section of the embodiment, and Fig. 3 is a diagram showing the irradiation and detection area of the embodiment. FIG. 4 is an explanatory diagram showing the ideal positional relationship of the light emitting and light receiving openings, and FIGS. 5 and 6 are a perspective view and a front view of the detection unit showing a conventional example. 1... Lamp house, 2... Light emitting opening, 3
... Light-receiving opening, 4... Light-emitting section, 5... Light-receiving section, A... Paper to be detected.

Claims (1)

[Scope of utility model registration request] This is a reflection type photo sensor in which a light emitting opening and a light receiving opening are provided in the lamp house, and a light emitting part and a light receiving part are arranged inside the lamp house so that the irradiation area and the detection area on the detection paper passing surface partially overlap. In the interrupter, both of the openings are formed into slits that extend in a direction perpendicular to the moving direction of the paper to be detected, are lined up next to each other on a straight line along the extending direction, and are slit-shaped in the direction of movement of the paper to be detected. A reflective photo interrupter characterized by having a positional relationship having the following characteristics.