JPH07137887A - Paper sheet detecting device - Google Patents

Abstract

PURPOSE:To provide a paper sheet detecting device whereby accuracy of detecting a paper sheet can be improved by setting a margin for a threshold value of a light receiving level for judging whether the paper sheet is provided or not. CONSTITUTION:A paper sheet conveying path 3 for guiding a paper sheet, conveyed by a paper sheet conveying part, is provided, reflecting photoelectric detector 9 opposed to the paper sheet 6 is arranged to be opposed to a louver 19, tilted in a direction along almost relating to an optical axis direction of a light emitting element 9a of this photoelectric detector 9, by interposing the paper sheet conveying path 3 therebetween, so that a light receiving element 9b of the photoelectric detector 9 is shielded against the outside light by the louver 19, and also light (b) from the light emitting element 9a is directed to a direction different from the light receiving element 9b when the paper sheet 6 is not provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various image forming apparatuses,
The present invention relates to a sheet detection device for detecting a sheet to be conveyed in an image reading device or the like.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus or an image reading apparatus, the conveying state of a paper sheet to be supplied is detected and various operations are controlled by the detection signal. Therefore, FIG.
As shown in FIG. 2, the two guide plates 1 and 2 are opposed to each other to form a paper sheet conveyance path 3, and the actuator 7 is displaced by the paper sheet 6 conveyed by the paper sheet feed rollers 4 and 5. There is a paper sheet detection device that detects the tip position of the paper sheet 6 and the passage of the paper sheet 6 by detecting the movement of the actuator 7 by the sensor 8. However, the reaction of the actuator 7 changes due to variations in the stiffness of the paper sheet 6, and the paper sheet 6 is detected via the actuator 7, so the accuracy of the detection position is reduced.

From the above, as shown in FIG.
A reflection type photoelectric detector 9 is provided on one of the guide plates 1 and 2 facing each other, and the paper sheet 6 conveyed by the paper sheet feed rollers 4 and 5 reaches the front surface of the photoelectric detector 9. At this time, the light receiving element (not shown) receives the light emitted from the light emitting element (not shown) of the photoelectric detector 9 and reflected from the paper sheet 6 to detect the paper sheet 6. There is a paper sheet detector.

[0004]

A reflection type photoelectric detector 9 is provided.
In the case of using, the light receiving element of the photoelectric detector 9 needs to be shielded from the external light which causes a false detection in order to improve the detection accuracy. In general, as shown in FIG. 5, external light is blocked by a guide plate 1 for guiding the paper sheet 6. Therefore, the light emitted from the light emitting element of the photoelectric detector 9 is reflected by the paper sheet 6 when the paper sheet 6 exists, and
When there is not, it is reflected by the inner surface of the guide plate (light shield plate). In this case, by setting the reflectance of the guide plate 1 smaller than the reflectance of the paper sheet 6, the amount of light received by the light receiving element differs between the reflected light from the paper sheet 6 and the reflected light from the guide plate 1. Therefore, the presence or absence of the paper sheet 6 is detected by comparing the magnitude of the output of the light receiving element with the threshold value as a reference.

However, when handling a paper sheet 6 having a color other than white and having a low reflectance, the light receiving amount of the light reflected from the paper sheet 6 and the light receiving amount of the light reflected from the guide plate 1 are determined. The difference becomes small, it becomes difficult to set the threshold value for distinguishing both lights with a margin, and the detection accuracy of the paper sheet 6 decreases.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a reflection type photoelectric detector facing a sheet is provided with a sheet conveying path for guiding the sheet conveyed by a sheet conveying section, and this photoelectric detection. A louver inclined in a direction substantially along the optical axis direction of the light emitting element of the container is disposed so as to be opposed to each other with the paper sheet conveying path in between.

[0007]

The external light directed to the light receiving element of the reflection type photoelectric detector is blocked by the louver. When a paper sheet is present in front of the photoelectric detector, the light emitted from the light emitting element and reflected from the paper sheet enters the light receiving element. When there is no paper sheet in front of the photoelectric detector, the light emitted from the light emitting element is directed by the louver in a direction different from the direction toward the light receiving element. Therefore, it is possible to increase the difference in the amount of light received by the light receiving element depending on the presence / absence of a paper sheet and set the threshold value for determining the presence / absence of a paper sheet in consideration of a margin.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. The same parts as those described in FIGS. 4 and 5 are designated by the same reference numerals, and the description thereof will be omitted. As shown in FIG. 2, there is provided a paper sheet transport path 3 formed by facing the guide plates 1 and 2. An opening 10 is formed at the center of each of the guide plates 1 and 2, and a platen 11 and a print head 12 are arranged in the opening 10 so as to face each other. The print head 12 is held by a carrier (not shown) that reciprocates along the platen 11, and a ribbon cassette 13 is detachably attached to this carrier. In addition, the paper transport path 3
The paper feed rollers 4 and 5 that are forward / backward rotatable, which are paper feed units, are disposed in front of and behind the platen 11.

A reflection type photoelectric detector 9 is fixed to the guide plate 2, and a window 14 facing the photoelectric detector 9 is formed in a part of the guide plate 1, and the window 14 is transparent. A support plate 15 made of synthetic resin is provided. Further, the upper space of the paper sheet transport path 3 is covered with an opaque cover 16, and a transparent opening / closing cover 17 is rotatably held on a front surface of the cover 16 about a fulcrum shaft 18.

However, as shown in FIG. 3, a plurality of louvers 19 are embedded in the support plate 15. Figure 1
As shown in FIG. 1A, the photoelectric detector 9 has a light emitting element 9a and a light receiving element 9b which are arranged in a V shape.
As shown in (b), the light b emitted from the light emitting element 9a
Each louver 19 is inclined so as to be substantially parallel to the optical axis direction of.

In such a structure, as shown in FIG. 2, the paper sheet (recording paper) 6 is inserted from the lower edge of the opening / closing cover 17, and is moved backward (rightward in FIG. 2) by the paper feed rollers 4 and 5. ) And printed by the print head 12.
The paper sheet 6 guided to the paper sheet transport path 3 is detected by the photoelectric detector 9. The detection operation will be described below with reference to FIG. FIG. 1A shows a state in which the paper sheet 6 has not reached the front surface of the photoelectric detector 9. In this state, the light emitting element 9a is not shielded from the external light a, but the external light a with respect to the light receiving element 9b.
Is blocked by the inclined louver 19. Also, FIG.
As shown in (b), the light b from the light emitting element 9a goes outward from between the louvers 19 substantially parallel to the optical axis direction.
Even if the light b from the light emitting element 9a is diffused and is incident on the louver 19 at a certain incident angle, the incident angle is extremely small, and thus the light is reflected upward by the louver 19. That is, in the state shown in FIGS. 1A and 1B, the amount of light received by the light receiving element 9b is extremely low.

As shown in FIG. 1C, when the paper sheet 6 reaches the front surface of the photoelectric detector 9, the light c emitted by the light emitting element 9a and reflected by the paper sheet 6 is received by the light receiving element 9b.
Is incident on. The level of the amount of received light at this time is as shown in FIG.
It is a level with a large difference compared to the state of. Therefore, it is possible to set the threshold value for determining the presence / absence of the paper sheet 6 in consideration of the margin, and thereby, the detection accuracy of the paper sheet 6 can be made extremely high. Further, since a predetermined interval is provided between the plurality of louvers 19, it is convenient that the result immediately after printing can be seen from that interval.

The louver 19 may be directly attached to the guide plate 1. Further, when sufficient space is secured above the window 14, the back side of the window 14 (right side in FIG. 3)
You may use one louver which inclines upward gradually as it goes from one side to this side of this side.

[0014]

According to the present invention, a reflection type photoelectric detector facing a paper sheet and a louver inclined in a direction substantially along the optical axis direction of the light emitting element of the photoelectric detector are conveyed. Since they are arranged facing each other with the path in between, the louver can block the external light directed to the light receiving element of the reflection type photoelectric detector, and when there is a sheet in front of the photoelectric detector, the light emitting element is used. The light emitted from the light can be reflected by the paper sheet passing in front of the louver and incident on the light receiving element. Furthermore, when there is no paper sheet in front of the photoelectric detector, the light emitted from the light emitting element is The louver can be directed in a direction different from the direction toward the light receiving element. Therefore, even when using a paper sheet having a low reflectance, a threshold for determining the presence or absence of the paper sheet is set with a margin, and Detection accuracy can be extremely high

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, (a) is a vertical cross-sectional side view showing a state in which a light receiving element is shielded from external light, (b).
FIG. 4A is a vertical sectional side view showing a paper sheet non-detection state, and FIG.

FIG. 2 is a vertical side view showing the overall structure.

FIG. 3 is a perspective view showing a louver support structure.

FIG. 4 is a vertical sectional side view showing a conventional example.

FIG. 5 is a vertical sectional side view showing another conventional example.

[Explanation of symbols]

 3 paper sheet conveying path 4,5 paper sheet conveying section 6 paper sheet 9 photoelectric detector 9a light emitting element 19 louver

Front page continuation (72) Inventor Isao Adachi 570 Ohito, Ohito-cho, Tagata-gun, Shizuoka Prefecture Tokyo Denki Co., Ltd. Ohito factory (72) Hideki Sano 570 Ohito, Ohito-cho, Takata-gun, Shizuoka Tokyo Ohki Co., Ltd. in the factory

Claims (1)

[Claims] 1. A reflection type photoelectric detector facing a paper sheet provided with a paper sheet conveying path for guiding a paper sheet conveyed by a paper sheet conveying section, and an optical axis direction of a light emitting element of the photoelectric detector. The sheet detecting device is characterized in that the louver inclined in a direction substantially along with is disposed opposite to each other with the sheet conveying path in between.