JPH062153Y2 - Sheet detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial field of application The present invention relates to a sheet detection device of a sheet processing device such as an automatic document feeder, a copying machine, a printing machine, and a printer. The present invention relates to a sheet detection device that optically detects.

(B) Conventional technology As a device for detecting a sheet, a light emitting element (for example, LED) and a light receiving element (for example, phototransistor, photodiode) are arranged to face each other, and an optical path is formed between these two elements. A transmissive photosensor that detects a sheet by blocking the sheet with a sheet is widely known.
In this type of sensor, as shown in FIG. 6, the detection capability between the light emitting element 50 and the light receiving element 51 (generally S / N
In order to increase the ratio), the front surfaces of the light emitting element 50 and the light receiving element 51 are covered with shielding plates 52 and 53 having long hole slits 52a and 53a, respectively, and the slits 52a and 53a are positioned in the same positional relationship to form an optical path. As shown in FIG. 7, or as shown in FIG. 7, the shield plates 55 and 56 are provided with pinholes (small circular through holes) 55a and 56a, and the pinholes 55a and 56a form an optical path. It has been understood that some have improved detection capability, and in order to enhance the detection capability of the sensor, it is better to configure the optical path with the pinholes 55a and 56a.

(C) Problems to be solved by the invention By the way, in a sheet detection device which has a pinhole structure and narrows the optical paths of the light emitting element and the light receiving element to form a sensor, the pinholes are accurately positioned relative to each other. Without this, the light paths between the light-receiving element and the light-emitting element do not match, and many adjustments must be made to match this light path.In addition, paper dust on the sheets to be handled or dust inside the device may cause pinholes. Causing clogging
The disadvantage is that it often becomes undetectable.

Further, in the case where a slit is provided on the front side of the light emitting element and the light receiving element and the slits are provided in the same direction,
Although the sheet can be detected even if the above-mentioned positioning adjustment is rough, the detection capability of the sensor cannot be improved as much as the one using the pinhole, and the sensor malfunctions.

Therefore, an object of the present invention is to provide a configuration in which the mounting work of the sensor is easy and to improve the detection capability of the sensor, and thus to solve the above-mentioned problems.

(D) Means for Solving the Problems The present invention has been made in view of the above circumstances, and as shown in FIG. 1, for example, a light emitting path (20a) and a light receiving section (2).
0b) and a pair of shielding members (21, 22a) each having a transmission hole (21a, 22a) are arranged to face each other,
In a sheet detecting device (20) which detects the presence or absence of a sheet P by the presence or absence of interruption of an optical path (21a ', 22a') formed between these transmission holes (21a, 22a),
The both transmission holes (21a, 22a) are slits of a predetermined length, and the slits are configured such that their longitudinal directions intersect with each other in the projection direction.

(E) Action Based on the above-described configuration, the sheet detection device (20) is extremely easy to adjust the light emitting section (20a) and the light receiving section (20b), and is highly accurate despite the extremely simple adjustment. Detect the sheet.

Note that the above reference numerals are shown for reference and do not limit the configuration in any way.

(F) Embodiment An embodiment in which the present invention is applied to an automatic document feeder will be described below with reference to the drawings.

As shown in FIG. 2, the automatic document feeder 1 has a document table 2 and a conveyor belt 5 arranged so as to cover the platen glass 4 of the image forming apparatus 3.
A paper feed roller 6 is provided below the document placing table 2, and a separation unit 7 including a separation unit conveyance belt 7 a and a separation roller 7 b is provided adjacent to the paper feed roller 6.
The sheet originals P stored in the original placing table 2 are separated from the lower one and conveyed one by one. Separation part 7
A sheet feeding path 9 extending in the direction of the platen glass 4 is disposed downstream of the sheet feeding path 9, and a registration roller 10 is disposed in the middle of the sheet feeding path 9. Is guided to the platen glass 4 via the registration roller 10. Further, a paper discharge path 11 is provided above the separating portion 7, and the paper discharge path 11 guides the sheet original P from the platen glass 4 along the left side of the large roller 12 in the drawing.

On the right side of the large roller 12 in the drawing, a reversing path 13 and a flapper 14 for a double-sided document that branch from the paper discharging path 11 and join the paper feeding path 9 are provided.

The automatic document feeder 1 has a structure that can be opened and closed with respect to the platen glass 4, and has an upper cover 16, a flapper support member 15 that supports the flapper 14, and a lower cover that guides the sheet document P to the large roller 12. Reference numeral 17 is configured to be openable / closable so that the jammed sheet document P can be removed when the sheet document P is jammed in the apparatus.

A registration section sensor 20 is provided near the registration roller 10, and the registration section sensor 20 is provided.
3, the light emitting element (LED) 20a arranged below the reverse path guide plate 13a forming the reverse path 13 and the paper feed path guide plate forming the paper feed path 9 are shown in FIG. A light receiving element (phototransistor) 20b arranged below 9a is provided.
The a and the light receiving element 20b are arranged so as to face each other, and an optical path is formed between the light emitting element 20a and the light receiving element 20b. The light emitting element 20a and the light receiving element 20b are covered by a light emitting section cover 21 and a light receiving section cover 22, respectively,
The light emitting unit cover 21 is provided with a transmission hole (slit) 21a, and the light receiving unit cover 22 is provided with a transmission hole (slit) 2a.
2a is provided. Then, light through holes 23 and 25 are opened at positions corresponding to the optical paths formed between the light emitting element 20a and the light receiving element 20b of the reverse path guide plate 13a and the paper feed path guide plate 9a, respectively. Light from the light emitting element 20a penetrates through the through holes 23 and 25.

The paper feed path guide plate 9 above the light receiving element 20b.
A cleaning hole 30 is opened in a, and a mylar 31 for blocking the cleaning hole 30 is provided so that the light receiving element 20b can be easily cleaned.

The registration sensor 20 detects the leading edge of the sheet document P and controls the rotation of the registration roller 10, or controls the trailing edge of the sheet document P to stop the operation of the conveyor belt 5. To the jam judgment circuit for judging whether the presence or absence of the sheet original P is proper or not, and outputs the detection signal of the presence or absence of the sheet.

Further, a reverse path entrance sensor 27 is arranged in the path 26 that guides the sheet original P to the large roller 12, and the sensor 27, like the registration sensor 20 described above, has a light emitting element 27 a facing the light receiving element 27 a and a light receiving element 27 a. And the element 27b.

Hereinafter, the positional relationship between the sensors 20 and 27 will be described with reference to FIG. 1 by taking the registration sensor 20 as an example.

The light emitting element 20a has a light emitting portion cover 21 as a shield plate that covers the light emitting element 20a in order to prevent light diffusion, and the transmission hole 21a is formed in the cover 21 in a vertically long shape. Is configured as a slit hole. On the other hand, like the light emitting element 20a, the light receiving element 20b is also covered with the light receiving portion cover 22, and the light receiving portion cover 22 is formed with the above-mentioned transmission hole 22a as a horizontally elongated slit hole having a predetermined length. . Both the light emitting element 20a and the light receiving element 20b form an optical path by the slit holes 21a and 22a.
Since a has different phases and intersects with each other, the optical path from the light emitting element 20a becomes an optical path 21a 'which is elongated in the projection direction, as shown when the optical path is blocked by the sheet document P as shown in the figure. The optical path from the light receiving element 20b becomes a laterally elongated optical path 22a 'in the projection direction, and the optical axis of the optical path constitutes a pinhole 29 near one point.

This makes it impossible for the sensor 20 to have the same detection ability as that of the pinhole type sensor. Also,
Each of the light paths of the light emitting elements 20a has a vertically long slit 21.
Since the slit 22a is a and has a horizontally long slit 22a, it is possible to detect the sheet document P by forming one point of the optical path between the slit lengths. Further, since the slit is formed with a predetermined area, it is not clogged with paper dust from the sheet original P or dust in the apparatus.

In the above embodiment, the slits 21 of the sensor covers 21 and 22 of the light emitting element 20a and the light receiving element 20b.
Although the a and 22a are arranged in a positional relationship of crossing each other at right angles, the present invention is not limited to this, and as shown in FIG. 4, the slits 21b and 22b of the covers 21 and 22 of the light emitting part and the light receiving part have different optical paths. May be arranged so as to be out of phase with each other.

Further, as shown in FIG. 5, the cover 2 for the light emitting portion and the light receiving portion
It goes without saying that slit holes 32a and 33a may be provided in the guide plates 32 and 33 that form the sheet conveying path so that the slits 32a and 33a are shifted in phase and intersect each other without providing slit holes in 1 and 22.

(G) Effect of the Invention As described above, according to the present invention, both transmission holes of the light emitting portion and the light receiving portion are slits of a predetermined length, and both transmission holes have their longitudinal directions intersecting in the projection direction. As a result, the sheet detection capability (S / N ratio) can be improved, and at least the slit holes need only have a crossing relationship, so adjustment at the time of mounting is unnecessary, and there is no influence of paper dust or dust. It is possible to provide a difficult sheet detection device.

[Brief description of drawings]

FIG. 1 is a layout view of a sensor according to an embodiment of the present invention, FIG. 2 is a side view of an automatic document feeder adopting the present invention, FIG. 3 is a partially enlarged view thereof, and FIGS. Is a layout of sensors showing another embodiment, and FIGS. 6 and 7 are layouts of conventional sensors. 20 ... Sheet detecting device (resist part sensor), 20a ... Light emitting part (light emitting element), 20b ... Light receiving part (light receiving element), 21 ... Shielding member (light emitting part cover), 22 ... Shielding member (light receiving part cover), 21a ... transmission hole, 22a ... transmission hole, 21a ', 22a' ... optical path, P ... sheet (sheet original).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsu Shinoda 3167 Yamamiya-cho, Kofu-shi, Yamanashi Nihon Seimitsu Kogyo Co., Ltd. (56) Reference JP 60-250281 (JP, A) 189880 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A light emitting portion and a light receiving portion are arranged opposite to each other through a pair of shielding members each having a transmission hole, and the presence or absence of a sheet is detected by the presence or absence of interruption of an optical path formed between these transmission holes. In the sheet detecting apparatus, the both transmission holes are slits having a predetermined length, and the slits are configured such that their longitudinal directions intersect with each other in the projection direction.