JPH0210055B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a paper detection device that can be used in electrostatic transfer copying machines or peripheral equipment used therein.

2. Description of the Related Art Structures of Conventional Examples and Their Problems In copying machines and their peripheral devices, devices are used everywhere that detect the passage of paper or the presence or absence of paper in the conveyance path of originals or copy paper. This paper detection device generally detects paper by installing a paper detector in the middle of passing the paper between a pair of paper guide plates, but with a mechanical detection method such as a micro switch, the part that contacts the paper is In order to give a subtle deformation, a reflective photo sensor is installed in the opening on one side of the paper guide, and the inside of the other paper guide plate is made black. There are many methods for detecting presence or absence.

However, recently, double-sided copy paper and color paper have become popular, and the paper is not necessarily white, making it difficult to distinguish between the reflectance of the paper and the paper guide plate, and various proposals have been made as a countermeasure.

FIGS. 1 and 2 are sectional views of essential parts showing two examples of the paper detection device. The configuration of this conventional example will be explained below. In FIGS. 1 and 2, 1 is a sensor, and this sensor 1 is composed of a light emitting section 2 and a light receiving section 3. 4 and 5 are paper guide plates, which guide the passage of the paper 6. 7 is another structural material that generally tends to be present near the paper detection device. The paper guide plate 4 is provided with an opening 4a through which the sensor 1 detects the paper 6.

Next, the operation of the above conventional example will be explained. 1st
In the figure, the operation of the sensor 1 will be explained. The sensor 1 is a reflective photo sensor that detects when the paper reaches the opening 4a, and the light from the light emitting section 2 is reflected by the paper 6 and enters the light receiving section 3. The presence of paper is detected based on the intensity of this incident light. The paper guide plate 5 is provided with an opening 5a so that when no paper 6 is present, the light from the light emitting section 2 passes through and is not reflected at the light receiving section 3.

The method shown in FIG. 2 is the same as the method shown in FIG. 1 when the paper 6 reaches the opening 4a, but when there is no paper, the inner surface of the recess 5b formed in the paper guide plate 5 is The distance between the sensor 1 and the paper 6 is larger than the distance between the paper 6 and the sensor 1, and therefore, the light from the light emitting section 2 reflected on the inner surface of the recess 5b is attenuated and reaches the light receiving section 3, indicating that no paper is present. Perform detection.

If double-sided copy paper, color paper, or the like is used as the paper 6, the light from the light emitting section 2 of the sensor 1 is attenuated when reflected by the paper 6, so that the light entering the light receiving section 3 becomes weaker. For this reason, the sensor 1 needed to have high sensitivity performance. However, if the sensitivity of the sensor 1 is increased, in the method shown in FIG. As if sensor 1
is a false positive.

Further, generally, the reflected light from the light emitting section 2 reaches the light receiving section 3 due to other structural members 7 existing near the opening 5a, and the sensor 1 often causes false detection. Next, in the method shown in FIG. 2, the recess 5b of the paper guide plate 5 is
The height of the recess cannot be made infinitely high, and is generally limited to several millimeters by design. For this reason, if the sensitivity of the sensor 1 is made high, false detection will often occur due to the reflected light from the inner surface of the recess 5b.

In general, the reflection type sensor 1 has a large variation in sensitivity, and it is impossible to use one with a constant sensitivity when producing in large quantities, and the reliability of paper detection is extremely unstable. Moreover, when the paper guide plates 4 and 5 are movable, the distance from the sensor 1 changes, which further reduces the reliability of paper detection.

OBJECTS OF THE INVENTION An object of the present invention is to provide a paper detection device capable of detecting all types of paper such as double-sided copy paper and color paper.

Structure of the Invention In order to achieve the above-mentioned object, the present invention forms an opening in a pair of guide plates, provides a reflective photo sensor consisting of a light emitting part and a light receiving part on the outside of one guide plate, and provides a reflective photo sensor consisting of a light emitting part and a light receiving part on the outside of one guide plate. The guide plate includes a reflecting plate inclined with respect to the paper passage path on the optical path of the light emitting part of the reflective photo sensor.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a cross-sectional view of a paper detection device in an embodiment of the present invention. In the figure, 1 is a sensor, and this sensor 1 is composed of a light emitting section 2 and a light receiving section 3. 4 and 5 are paper guide plates that guide the passage of the paper 6. 8 is composed of a cover etc. that blocks external light. 9 is a reflective plate formed on the paper guide plate 5.

Next, the operation of this embodiment will be explained.

In FIG. 3, when the paper 6 is not present in the opening 4a, the light from the light emitting section 2 is reflected by the inclined surface 5c of the reflection plate 9 provided on the paper guide plate 5 in the direction of the arrow in the figure. , almost no light enters the light receiving section 3. Therefore, even if the sensitivity of the sensor 1 is increased in order to detect double-sided copy paper or color paper with low reflectance, almost no light from the light emitting section 2 enters the light receiving section 3, so that there is no false detection that paper is present.

Next, when the paper 6 comes on top of the sensor 1, the light from the light emitting section 2 is reflected by the paper 6 and enters the light receiving section 3, and the presence of paper is detected. 8, the external light is the light receiving part 3
This is a light blocking cover to prevent false detection due to light entering the sensor.

In this way, the light from the light-emitting part 2 of the sensor 1 does not reach the light-receiving part 3 except for the light reflected by the paper 6, so the sensitivity of the sensor 1 can be made sufficiently high, and even if there are many variations, the paper can be faithfully processed. Detects the presence of 6.

Note that the same effect can be obtained even if the surface of the reflecting plate 9 is folded in multiple stages.

FIG. 4 is a sectional view showing another embodiment of the present invention. In this embodiment, the inclined surface 5c of the reflection plate 9 of the paper guide plate 5 in the embodiment shown in FIG. 3 is replaced with an arcuate surface 5d. The other sensors 1, light emitting section 2, light receiving section 3, paper guide plate 4, paper 6, and cover 8 are the same as those explained in FIG. 3, and therefore are given the same reference numerals.

Even with the configuration of this embodiment, the light from the light emitting section 2 does not reach the light receiving section 3 other than the light reflected by the paper 6, so the sensitivity of the sensor 1 can be made sufficiently high, and there is a large amount of variation. The effect of faithfully detecting the presence of the paper 6 even when the paper 6 is in use can be obtained.

Effects of the Invention As is clear from the above explanation, since the paper detection method does not directly contact the paper, it does not cause slight deformation to the paper or provide resistance to the running of the paper 6, and it is possible to prevent the paper from being double-sided copy paper. If a sensor with a sufficiently high sensitivity is used even for color paper, it is a highly reliable paper detection device that can reliably detect paper even if there are many variations, and is suitable for mass production. Furthermore, it has the advantage that it is not affected by external light, has no problem even if there are other structural materials nearby, and has very few design restrictions. Moreover, there is almost no cost increase in carrying out the present invention, and the present invention is highly practical.

[Brief explanation of drawings]

1 and 2 are enlarged sectional views of main parts of a conventional paper detection device, and FIGS. 3 and 4 are enlarged sectional views of main parts of a paper detection device according to an embodiment of the present invention. 1...Sensor, 5, 5c, 5d...Paper guide plate, 8...Cover, 9...Reflector.

Claims (1)

[Claims] 1. An opening is formed in a pair of guide plates, a reflective photo sensor composed of a light emitting part and a light receiving part is provided on the outside of one of the guide plates, and a light emitting part of the reflective photo sensor of the other guide plate is provided. A paper detection device characterized in that a reflecting plate is provided on the optical path of the paper, the reflecting plate being inclined with respect to the paper passage path, and a cover is provided on the reflecting plate.