JPH03238251A - Sheet material detection device - Google Patents

Abstract

PURPOSE:To reduce complexity of adjusting an optical axis and influence by paper particles or the like by constituting an emission part as a plane light- emission means, and disposing a condenser lens between a light receiving part and a sheet material to be detected for improvement in detecting ability of a sheet material and so forth without the use of a shield member. CONSTITUTION:A light-emission part 27a consists of an emission element 271 and a diffusion plate 272 and is covered by an emission part cover 275 to be protected. Then the diffusion plate 272 is disposed so that the emission part 27a may be a plane light-emission body. Besides, in order to prevent paper particles and so forth from adhering to the surface of the emission part cover 275, the cover 275 is protruded into a sheet material passage range a little so that a sheet member P may come into sliding-contact with the surface of the cover 275. On the other hand, a light receiving part 27b consists of a lens 273 and a light receiving element 274, and a lens cover 276 and a light receiving part cover 277 are provided to protect them. The light receiving part cover 277 is disposed so that it may cover whole part of the light receiving part 27b in order to prevent paper particles and s forth from entering and adhering to the light receiving element 274, the lens 273 and so on.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sheet material detection device used for detecting the edge of a sheet material such as a sheet original moving in a copying machine, a recording device, etc., for example.

(Prior Art) Conventionally, this type of device has a light emitting section 101 and a light receiving section 10.
The photocoupler lO shown in FIG.
O is known and commercially available. However, when this type of photocoupler is applied to a copying machine or the like to detect a sheet original, the position for detecting the edge of the sheet material P is set at a position corresponding to the detection deviation in the direction perpendicular to the conveyance direction of the sheet material P. Since it is necessary to improve the latitude and there is a risk of false detection in the case of sheet materials such as perforated originals, it is desirable to perform detection in the center of the sheet material passage area.

Therefore, if it is not desirable to use a commercially available photocoupler to detect the sheet material as shown in Fig. 8, the light emitting part and the light receiving part should be separated and placed facing each other as shown in Fig. 9 and Fig. 1O. Generally, those that are arranged to form an optical path are often used.

In other words, in this type of sensor, as shown in FIG. The front surfaces of the light receiving element 150 and the light receiving element 151 are covered with shielding plates 152 and 153 having elongated slits 152a and 153a, respectively.

153a arranged in the same positional relationship to form an optical path, or as shown in FIG. 10, shielding plates 155 and 156
, pinholes (small circular through holes) 155a, 1
56a, and these pinholes 155a and 156a constitute an optical path to increase the detection ability of the detection device.
It is generally well understood that it is better to configure the optical path by 5a and 156a.

(Problem to be Solved by the Invention) However, in such conventional technology, the device is constructed by providing a slit or pinhole structure as described above to narrow down the optical path from the light emitting part to the light receiving part. It is necessary to match the optical path from the pinhole, etc. to the light receiving part; if they do not match, the optical path will be blocked, making it impossible to detect the sheet material. Therefore, there is a problem in that many adjustments must be made when assembling the device and installing it in a copying machine, etc., making the work complicated.

There is also the problem that paper powder from the sheet material being handled or dust within the device may clog the 1st pinhole or 3/1st pinhole, blocking the optical path and rendering detection unusable.

The present invention has been made to solve the problems of the prior art described above, and its purpose is to improve the detection ability of sheet materials without using shielding members such as slits and pinholes, and to adjust the optical axis. It is an object of the present invention to provide a sheet material detecting device which is easy to install without the need for any of the above, and is free from the fear of being clogged by paper powder or the like.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, a light emitting section and a light receiving section are arranged, an optical path is formed from the light emitting section to the light receiving section, and a light path is formed in a predetermined direction. In a sheet material detection device that detects a sheet material when it is conveyed and passes through and blocks the optical path, the light emitting section is configured as a planar light emitting means, and the light emitting section is configured as a planar light emitting means, and the light emitting section is configured as a planar light emitting means. It is characterized in that a lens for condensing light onto the light receiving section is disposed.

Further, it is preferable that the lens is arranged such that the focal point is located on the light receiving surface of the light receiving section and within the sheet material passage area, and is conjugate with the light receiving surface of the light receiving section.

The above lens can be easily formed as a ball lens.

Note that it is desirable to arrange visible light cutting means between the light receiving section and the sheet material passage area.

(Function) Thus, the light emitted from the light emitting section is reliably focused on the light receiving section, and the passing sheet material can be reliably detected. Further, the sheet material can always be accurately detected without being adversely affected by paper dust or the like on the sheet material.

(Example) The present invention will be explained below based on the illustrated example. A case in which a sheet material detection device according to an embodiment of the present invention is applied to an automatic sheet document feeding device will be described with reference to FIGS. 1 to 3.

First, an overview of the automatic document feeder for sheet documents will be explained. As shown in FIG.
A conveyor belt 5 is provided so as to cover the platen glass 4.

A paper feed roller 6 is provided below the document table 2, and a separating section 7 consisting of a separating section conveyor belt 7a and a separating roller 7b is provided adjacent to the paper feeding roller 6.
A 0-separation unit 7 configured to separate and convey the sheet originals P stored on the original placing table 2 one by one from the lower ones.
A paper feed pasta extending in the direction of the platen glass 4 is disposed downstream of the paper feed path 9, and a registration roller 10 is disposed in the middle of the paper feed path 9, and the paper feed pasta registers the sheet document P. It is guided onto the platen glass 4 via the roller IO. Further, above the separating section 7, a paper discharge path 11 is provided, and the paper discharge bus 11 guides the sheet document P from the platen glass 4 along the left side of the large roller 12 in the figure.

To the right of the large roller 12 in the figure are reversing paths 13 and 7 for double-sided documents that branch from the paper ejection bus 11 and join the paper feed bus 9.
A rattle 14 is provided.

The automatic document feeder l has a structure that can be opened and closed with respect to the platen glass 4, and has an upper cam 16, a flapper support member 15 that supports the flapper 14, and a lower part that guides the sheet document P to the large roller 12. The cover 17 is configured to be openable and closable in order to remove the jammed sheet document P if the sheet document P becomes jammed in the apparatus.

As shown in FIG. 3, which is a partially enlarged view of the main part of FIG.
A sheet material detection device 27 as a reversal path entrance sensor is disposed at 6, and this device 27 is connected to the opposite light emitting section 2.
7a and a light receiving section 27b.

Below, the configuration of the sheet material detection device 27 according to the present invention will be explained based on FIG. 1. Light emitting section 27
a is composed of a light emitting element 271 and a diffusion plate 272. This light emitting section 27a is covered and protected by a light emitting section cover 275. Here, by disposing a diffuser plate, the light emitting portion becomes a planar light emitter. The light emitting unit cover 275 is made of transparent acrylic or the like, and covers the diffuser plate 2.
72 in a predetermined position, and also covers the light emitting element 271 and the diffusion plate 272 to prevent paper dust from entering and adhering thereto.

In order to prevent paper dust and the like from adhering to the surface of the light emitting section cover 275, the sheet material P slightly protrudes from the sheet material passing area so as to rub against the surface of the cover 275.

On the other hand, the light receiving section 27b includes a lens 273 and a light receiving element 274.
and a lens cover 2 to protect them.
76, a light receiving section cover 277 is provided. Here, the lens 273 is arranged with high precision by using a spherical ball lens, and is arranged at a position where the light receiving surface of the light receiving element 274 and the focal point of the sheet material are conjugated with each other within the passage area of the sheet material. .

In addition, a visible light cut filter 278 for cutting unnecessary visible light such as external light is provided between the light receiving section 27b and the passage area of the sheet material P.In this device, a visible light cut filter 278 is provided inside the lens cover 276. It is designed to be placed in

The light receiving unit cover 277 covers the light receiving element 274° lens 2.
73 etc. to prevent paper dust from entering and adhering to the light receiving section 27.
b is arranged so as to cover the entire area. Further, this lens cover 276 is fixed to prevent paper dust etc. from adhering to the surface of the visible light cut filter 278, and furthermore, a sheet material P is fixed to prevent paper dust etc. from adhering to the surface of the cover 276. It slightly protrudes from the sheet material passing area so as to rub the surface of the cover 276.

According to the automatic document feeder to which the sheet material detection device of the present invention having the above configuration is applied, the sheet material can be detected reliably. In other words, the receiver between the platen glass 4 and the large roller 12 can ensure the detection of a jam at the time of transfer and the detection for determining the timing for controlling the speed of the paper ejection roller.

Furthermore, even if used for a long time, clogging due to paper dust etc. does not occur.

In the device of this embodiment, in order to perform accurate detection, a visible light cut filter 278 is provided as visible light cut means to prevent unnecessary light from entering, but the lens 273. A similar effect can also be obtained by using a lens cover 276 made of resin that blocks visible light.

FIG. 4 shows a second embodiment of the invention. Components that are the same as those in the first embodiment described above are given the same reference numerals and will be described. Embodiment 2 shows the case where a normal convex lens is applied to the lens 273, and the lens 273 is also used in this embodiment. A focal point exists within the light-receiving portion of the light-receiving element 274 and the passage area of the sheet material P, and is arranged so as to be conjugate.

Even with the apparatus of this embodiment, the sheet material can be detected accurately as in the first embodiment. In addition, although a visible light cut filter is not provided in this embodiment, by providing a visible light cut filter, the sheet material can be detected more accurately by rotation.

In the above-mentioned embodiment, a combination of a light emitting element and a step plate was used as the planar light emitting means, but it is also possible to use a generally commercially available planar light emitting LED or a planar light emitting EL panel as shown in FIG. You can get the same effect by using it.

Furthermore, in the second embodiment described above, the case where only one lens is used is shown, but if multiple lenses are used as shown in FIG. 6, the conjugate long lens can be shortened and the device can be made smaller. is a rotation.

(Effects of the Invention) The present invention has the above-described structure and operation, and the light emitting section is configured as a planar light emitting means, and a lens for condensing light is disposed between the light receiving section and the sheet material to be detected. This improves the detection ability of sheet materials, etc. without using shielding members such as pinholes and slits, and reduces the disadvantages of using the above-mentioned shielding members, such as the complexity of optical axis adjustment and the effects of paper dust, etc. It is possible to provide an integrated sea material/material detection device.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an outline of a sheet material detection device according to a first embodiment of the present invention, and FIG. 2 is a diagram showing an overall outline of an automatic document feeder to which the sheet material detection device according to the first embodiment is applied. 3 is an enlarged view of the main part of FIG. 2, FIG. 4 is a diagram showing an outline of the sheet material detection device according to the second embodiment of the present invention, and FIG. 5 is an enlarged view of the main part of FIG. FIG. 6 is a diagram showing an example of a combination of a plurality of lenses, and FIGS. 7 to 10 are diagrams showing conventional sheet material detection devices. Explanation of symbols 27a... Light emitting section 27b... Light receiving section 271.2
72... Planar light emitting means (271... Light emitting element, 27
2... Diffusion plate) 273... Lens (hole lens) P... Sheet material Rin 11 Figure 4 Figure 02 Figure 8 Figure 5 Figure 9

Claims (1)

[Claims] (1) A light emitting part and a light receiving part are arranged to form an optical path from the light emitting part to the light receiving part, and when a sheet material conveyed in a predetermined direction and passing through the sheet material blocks the optical path. In the sheet material detection device for detecting the sheet material, the light emitting section is configured as a planar light emitting means, and a lens is disposed between the light receiving section and the sheet material to be detected to focus light onto the light receiving section. A sheet material detection device characterized in that: (2) The sheet material according to claim (1), wherein the lens is disposed such that the focal point is located on the light receiving surface of the light receiving portion and within the sheet material passage area and is conjugate with the light receiving surface of the light receiving portion. Detection device. (3) The sheet material detection device according to claim (1), wherein the lens is a ball lens. (4) The sheet material detection device according to claim 1, further comprising visible light cutting means disposed between the light receiving section and the sheet material passing region.