JP2911762B2 - Paper edge detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is effective when used, for example, in a copying machine with an automatic document feeder for automatically sending a document to a document table and reading an image of the document. The present invention relates to a paper edge detecting device for detecting a paper edge.

[0002]

2. Description of the Related Art FIG. 9 is a schematic view of a copying machine to which an automatic document feeder is attached.

As a general function and operation of the automatic document feeder, a sensor 31 for detecting the presence / absence of a document 2 stacked and placed on a document tray 1 is detected. Is input to When a copy start switch (not shown) of the copying machine 20 is operated, the paper feed rollers 3 and 4 and the paper feed belt 5 rotate in the direction of the arrow, and cooperate with the stop roller 6 for preventing double feed, thereby forming the upper part of the original. Separate only one sheet and transport it to the left side of the figure. At this time, the document passes through the vicinity of a document edge detection sensor 32 for detecting the edge of the document, and when passing, a signal is emitted from the sensor. The signal starts the rotation of the document transport belt 7 to carry the document to the left side of the belt 7. The conveyed original is sent onto the original platen glass 14 by the original conveying belt 7 and the pressing rollers 8 and 9 which rotate in accordance with the movement thereof so that the original end is positioned at the image reading end of the main body. . If the predicted time of the movement of the leading edge of the document, which is calculated from the time when the document passes near the document edge detection sensor 32 and the belt rotation speed set in advance, reaches the image reading edge 33, the document is conveyed. As the belt 7 stops rotating, the movement of the document also stops. When the original is pressed by an appropriate pressure by rollers 11-1, 11-2, and 11-3 behind the original transport belt 7 and is positioned on the original platen glass 14, the copying machine 20 starts reading the original and finishes the exposure. Then, the document which has completed image reading by rotating the document conveying belt 7 and the paper discharge roller again is discharged to the document discharge tray 21.

In the above-described operation, the document edge detection sensor 32 needs to accurately read the timing at which the leading edge of the document passes. For example, if the document conveying speed (belt rotation speed) is about 500 mm / sec and there is a reading error of 0.01 second, the positional accuracy of the document will be about 5 mm.

[0005] If the accuracy cannot be ensured, the "document predicted position" of the original document moving position obtained by calculation from the belt rotation speed set in advance will deviate from the reading position. The result is a remarkably defective copy such that all information cannot be copied.

Various sensors have conventionally been considered for detecting the edge of the original. Hereinafter, a conventional example of a typical document edge detection sensor will be described.

The mechanical sensing lever type is shown in FIGS. 10A and 10B. The lever 41 is arranged so as to block the paper path, and when a part of the lever is pressed by the leading end portion 25 of the paper passing through the paper path, the lever rotates clockwise, and the light flux of the photocoupler 42 arranged near the lever. Is configured to emit a signal by shielding light (a signal generation portion is not shown).

FIG. 11 shows an optical transmission type. In this configuration, the light emitter 45 and the light receiver 46 are arranged with the paper path 40 interposed therebetween. The light beam emitted from the light projector 45 irradiates the light receiver 46. When the paper 2 is conveyed through the paper path 40 and this light path is shielded, light irradiation to the light receiver is cut off and a signal is issued by another circuit (not shown).

FIG. 12 shows an optical sensor reflector type. A light emitting and receiving device including a light emitting device 45 and a light receiving sensor 46 is disposed on one side of the paper path 40, and a mirror 48 is arranged on the opposite surface, and a light beam from the light emitting device 45 is reflected by the mirror 48 toward the light receiving device 46. When the paper 2 passes, this light beam is blocked, and a signal is emitted from another circuit (not shown) connected to the light receiving sensor.

[0010]

However, these sensors have the following problems.

1: Mechanical sensing lever type: As shown in FIG. 10B, at the moment when the thin paper having low rigidity comes into contact with the lever at a high speed, the leading edge 25 of the moving paper loses the slight weight of the lever, and the bending detection timing is reduced. In addition to the disadvantage that the paper is delayed, the paper is jammed in a narrow paper path as a result of the bending of the leading edge of the paper.

2: Optical transmission type: the leading edge of the document is not bent because it does not contact the document, but independent electrical wiring is required in the apparatus with the paper path between the light emitter and the light receiver interposed, and it is necessary to assemble the apparatus. There are disadvantages that it takes time, the apparatus becomes large, and it becomes expensive.

3: Optical sensor reflector type: Although the electrical components such as the light source and the light receiving element of the projector can be arranged on one side of the paper path, the assemblability is improved. However, if the reflection surface becomes dirty with paper dust or the like, The sensitivity decreases, the S / N ratio decreases, and the detection accuracy deteriorates. Further, the mirror surface is formed of an aluminum plate or a material to which an aluminum-evaporated sheet is adhered, but the mirror surface may be corroded by moisture contained in paper or the like. Therefore, for long-term use, it was necessary to periodically replace the mirror if it was cleaned or corroded. During use of the device, the angle of the mirror is easily deflected by vibrations generated by the motor, etc., and the reflected angle of the light beam moves as indicated by 88. Therefore, it is possible to detect that the reflected light beam may not enter the light receiver. There was a disadvantage that it disappeared.

[0014]

According to the present invention, there is provided a light emitting / receiving unit having a light emitting element and a light receiving element, and a roof prism provided on a side opposite to the light emitting / receiving unit with respect to a paper conveyance path. , The roof prism includes a plurality of minute roof prisms each composed of two surfaces substantially parallel to the reflection surface between the two reflection surfaces. Further, in a paper edge detection device having a light emitting and receiving unit having a light emitting element and a light receiving element, and a corner cube prism provided on the opposite side of the paper transport path from the light emitting and receiving unit, the corner cube prism is And a plurality of minute corner cube prisms, each of which has three vertices substantially parallel to three reflecting surfaces forming a corner cube at a portion where the vertex is removed.

[0015]

1A and 1B are reference examples which are the basis for understanding the present invention.

A light projector 45 and a photoelectric sensor 46 as light sources
The roof prism 50 is disposed at a position opposing the roof projection / reception unit, and the paper 2 is disposed between the projection / reception unit and the roof prism so that the roof prism surface behind the reflection surface of the roof prism is placed in the air layer 55. Is surrounded by a cover 51 via

The roof prism 50 is injection-molded with a material such as plastic, for example, acrylic.

The two reflecting surfaces 52, 5 of the roof prism 50
3 are arranged at right angles, and the entrance and exit surfaces are arranged on the side opposite to the intersecting vertices. Outside the reflection surface, a cover 51 is arranged via an air portion 55. This cover can prevent the prism from being scratched by impact from the outside of the prism,
It prevents harmful light flux from entering the prism.

The light beam that has entered the prism inside substantially perpendicularly to the entrance / exit surface 54 enters the reflecting surface 52 at approximately 45 degrees.

In this case, since the refractive index of the air 55 outside the reflecting surface 52 is 1 and the refractive index of the acrylic constituting the prism 50 is about 1.49, it is applied to Snell's formula to calculate the behavior of the incident light beam. When viewed from the viewpoint, the product of (refractive index of plastic) and Sin (incident angle) is larger than the product of (refractive index of air) and Sin (angle of emergence), so that the angle of emergence cannot be calculated. It can be seen that the light is reflected without being transmitted, and that the treatment of the reflection film is unnecessary.

The reflected light flux is further incident on one of the reflection surfaces 53 at approximately 45 degrees, is totally reflected, and exits from the entrance / exit surface. The behavior of the light beam incident on the roof prism from the entrance / exit surface 54 exits at the same angle as the incident angle from the entrance / exit surface 54, but this behavior is shown in FIG.
Not affected by orientation. In the present invention, this characteristic is utilized, and when the light beam from the light source enters and exits the prism, the light beam exits at the same angle and stably irradiates the light receiving sensor.

FIGS. 2A and 2B show a first embodiment of the present invention, in which the angle between the two reflecting surfaces 62 and 63 of the roof prism, which is composed of two surfaces substantially parallel to the reflecting surface, is 90 degrees. This is a document edge detection sensor in which a plurality of roof prisms 65 having a small degree are arranged. The luminous flux 68 incident on the minute roof prism 65 returns to the incoming direction as shown in FIG. 2B and is not directed to the light receiver 46.

FIGS. 3A and 3B show a second embodiment in which a corner cube prism 70 is arranged in place of the roof prism of the apparatus of the first embodiment. The corner cube has the shape of a triangular pyramid with three parallel reflecting surfaces arranged at right angles to each other. Light rays incident from the 74 surface corresponding to the base of the triangular pyramid exit at the same angle as the incident angle with respect to the incident surface even if the posture of the corner cube changes in the directions A and B as shown in FIG. 3B. . The luminous flux of the light projector is made to enter from this 74 surface. The reflected light similarly exits from the 74 surface and enters the light receiver 46.

FIGS. 4A and 4B show a second embodiment of the present invention, in which a very small portion composed of three surfaces substantially parallel to the three reflecting surfaces forming the corner cube is provided at a portion where the apex of the corner cube is removed. This is a document edge detection sensor in which a plurality of corner cubes 75 are arranged. The light beam incident on the minute corner cube prism 75 does not irradiate the light receiver 46 because it is emitted from the prism at the coming angle.

FIGS. 5A, 5B, and 5C show a third embodiment, in which a cylindrical lens unit 80 having a generatrix 86 as an array direction of light emitters and receivers is arranged on the incident surface of a prism. FIGS. 5B and 5C show D views of FIG. 5A. FIG. 5B efficiently receives the light beam from the light projector 45 and takes it into the prism. In FIG. 5C, the light beam is focused on the light receiving sensor 46. Since the luminous flux of the light projector at the incident part of the cylindrical lens is condensed, and the light is again condensed toward the light receiver at the emission part, the transmittance of the prism can be increased. This makes it possible to use a relatively inexpensive low-light-quantity light source or low-sensitivity sensor.

FIGS. 6A, 6B and 6C show a fourth embodiment, in which a diffusion plate 90 is arranged near the light receiving surface of the light receiving sensor 46. FIG.
A diffuser 90 wider than the light-receiving surface is disposed in close contact with the light-receiving sensor, and a light beam emitted from the prism passes through a paper path, irradiates the diffuser 90, and is partially diffused and transmitted by the diffuser 90. Irradiates the light receiving sensor. By installing a diffuser plate on the light receiving surface, it is possible to cope with variations in the position of the sensor. Although the light intensity of the light source and the light receiving sensor must have some allowance, even if the light receiving position of the sensor slightly deviates from the position of the light beam emitted from the prism, the light is received and diffused by the diffusion plate wider than the light receiving area of the sensor, and at least Since the section can be configured to irradiate the light receiving surface of the sensor, the arrangement accuracy can be further relaxed and highly accurate detection can be performed. FIG. 6B shows an example in which a cylindrical lens is arranged, but the effect of this embodiment can be exerted even when there is no cylindrical lens.

FIG. 6B shows an example in which a cylindrical lens is arranged on the entrance surface of the prism. FIG. 6C is an example in which a diffusion plate 90 based on this embodiment of the second embodiment is additionally arranged.

FIGS. 7A and 7B show a fifth embodiment in which a slit 92 is disposed between the light emitting / receiving units 45 and 46 and the prism. The shape of the slit is set so as to be parallel to the direction of the side 28 of the end of the document whose longitudinal direction is to be detected. The material is made of sheet metal that does not transmit light. By narrowing the detection light beam in the paper bus portion, the change in the amount of light when the paper is blocking the light beam in the paper path portion can be made steep, so that the responsiveness due to paper passage is improved. In addition, since unnecessary light beams from portions other than the slit portion are blocked, stray light from the outside of the apparatus or the like can be removed before the light enters the light receiving portion, and stable detection with little noise can be performed.

FIGS. 8A and 8B show a sixth embodiment in which a light transmission medium 85, for example, a plate glass or a plastic flat plate, which is substantially parallel to the plane, is disposed between the light emitting / receiving units 45 and 46 and the paper path. Then, a hard coat for increasing the surface hardness is applied to the light beam entrance / exit surface 64 of the prism. Eliminating the irregularities around the paper path of the emitter and receiver This makes it possible to smoothly pass the paper, and to improve the wiping property of dust that has adhered to the optical path. 2. Since the paper passes through the surface of the transparent medium while sliding, the paper dust does not adhere to the optical path portion and is removed by the moving document, so that an optical path with a high transmittance can always be secured.
3. Since the hardness of the prism surface is increased, the entrance / exit surface is less likely to be damaged, and durability can be ensured.

[0030]

As described above, according to the present invention, since the apex of the prism is eliminated, the size of the prism can be reduced, which contributes to the size of the apparatus. Further, since the light beam incident on the micro prism is directed to the light projector and not to the light receiver, there is an effect that the paper edge can be accurately detected without detecting stray light.

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[Brief description of the drawings]

FIGS. 1A and 1B are reference examples, each showing an example using a roof prism. FIG.

FIGS. 2A and 2B are diagrams showing an example in which a plurality of minute roof prisms are provided and the roof prism is miniaturized in the first embodiment.

FIGS. 3A and 3B are reference examples showing an example in which a corner cube prism is used.

FIGS. 4A and 4B are diagrams showing a second embodiment, in which a plurality of minute corner cube prisms are provided and the corner cube prisms are downsized.

FIGS. 5A, 5B and 5C are views showing a third embodiment, in which a cylindrical lens is arranged on the lower surface of a prism.

FIGS. 6A, 6B, and C are diagrams showing an example in which a diffusion plate is arranged on a light receiving element in the fourth embodiment.

FIGS. 7A and 7B are diagrams showing an example in which a slit plate is arranged between a light emitter / receiver and a prism in the fifth embodiment.

FIGS. 8A and 8B are views showing a sixth embodiment, in which dust-proof glass is arranged on a light-receiving / receiving device and a prism is hard-coated.

FIG. 9 is an explanatory diagram of an example of a copying machine with a document supply device according to the present invention.

FIGS. 10A and 10B are explanatory diagrams of a conventional document edge detection sensor.

FIG. 11 is an explanatory diagram of a conventional document edge detection sensor.

FIG. 12 is an explanatory diagram of a conventional document edge detection sensor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 document tray 2 document 3, 4 feed roller 5 feed belt 6 stop roller 7 document feed belt 8, 9 press roller 11 press roller 14 platen glass 20 copier 21 document discharge tray 30 glass surface 40 paper path 45 Light source or light transmitter 46 Photoelectric sensor or light receiver 50 Dach prism 68 Light transmission 70 Corner cube 80 Cylindrical lens unit 90 Diffusion plate 92 Slit aperture

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B65H 7/14 B65H 43/08

Claims (6)

(57) [Claims] 1. A paper edge detecting device comprising: a light emitting and receiving unit having a light emitting element and a light receiving element; and a roof prism provided on a side opposite to the light emitting and receiving unit with respect to a paper transport path. A paper edge detecting device, comprising a plurality of minute roof prisms each composed of two surfaces substantially parallel to the reflection surface between the two reflection surfaces. 2. A paper edge detecting device comprising: a light emitting and receiving unit having a light emitting element and a light receiving element; and a corner cube prism provided on a side opposite to the light emitting and receiving unit with respect to a paper conveyance path. A paper edge detecting device, characterized in that the cube prism has a plurality of minute corner cube prisms formed of three surfaces substantially parallel to three reflection surfaces forming a corner cube at a portion where the apex is removed. 3. The paper edge detection device according to claim 1, further comprising a cylindrical lens having a generatrix in the arrangement direction of the light emitting element and the light receiving element on an entrance / exit surface of the prism. 4. The paper edge detecting device according to claim 1, further comprising a diffusion plate between a light receiving surface of the light receiving element and a paper conveyance path. 5. The paper edge detecting device according to claim 1, further comprising a slit between the light emitting and receiving unit and the prism. 6. An optically transparent medium having a substantially parallel plane is disposed between the light emitting / receiving unit and the paper transport path, and the paper passing therethrough is arranged so as to be in contact with the light incident / exit surface of the prism. 3. The paper edge detecting device according to claim 1, wherein a hard coat for increasing surface hardness is applied to the surface.