JP3055625B1 - Paper detection sensor in printer - Google Patents

Abstract

An object of the present invention is to enable a sheet to be reliably detected in the immediate vicinity of a sheet feed roller. SOLUTION: With reference to one shaft 11 of a paper feed roller pair, a reflector 23 is mounted to be inclined with respect to the paper surface via a reflector holder 24, and is attached to the other shaft 16 via a detector holder 21. The optical detector 20 is connected to the reflector 23
The paper p can be accurately detected without directly receiving the reflected light near the nip portion A of the paper feed roller pair and with a small detection output.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a paper detection sensor applied to a printer.

[0001]

2. Description of the Related Art In addition to a contact-type mechanical paper detection sensor, a paper transport path of a printer is disclosed in JP-A-63-3105.
An optical paper detection sensor including a light emitting element and a light receiving element as disclosed in Japanese Patent Application Laid-Open No. 0-206 is used.

In particular, a light-emitting element and a light-receiving element which are arranged in a direction perpendicular to the paper transport direction are suitable for a small printer because they require less space than a mechanical paper detection sensor. Because the reflective surface is arranged in a direction parallel to the paper transport direction, there is no problem for black paper, but for white paper or glossy paper whose reflectance is close to anti-slope. Has a disadvantage that it cannot be detected sufficiently, and since the detection sensor cannot be arranged sufficiently close to the paper feed roller, complicated control of the operation of the device according to the position of the paper must be performed. Such a problem is derived.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem.
An object of the present invention is to provide an improved sheet detection sensor capable of reliably detecting the presence or absence of a sheet regardless of the sheet.

It is another object of the present invention to provide an improved paper detection sensor which can be disposed as close as possible to required equipment.

[0005]

That is, according to the present invention, as a sheet detecting sensor in a printer for achieving the above object, a reflecting plate is provided so that its reflecting surface is inclined with respect to the sheet conveying surface. It is intended to be arranged.

[0006]

With this configuration, it is possible to determine whether or not a sheet is present with a small detection output by avoiding directly receiving the reflected light from the paper surface, and to make the detection sensor close to the paper feed roller. The sequence control mechanism can be greatly simplified.

[0007]

Embodiments of the present invention will be described below. The drawings all show one embodiment of the present invention. First, a schematic configuration of a small printer having the sheet detection sensor will be described.

This printer performs printing processing on continuous paper or cut paper fed from a push tractor 1 or a paper feed roller 2 provided at the back to a printing section, and the stacker / stacker provided at the front of the operation side. It is configured to be discharged onto the sheet guide 8, and for postcards and slips,
After the sheet is fed from the stacker and sheet guide 8 to the printing section, the sheet is discharged to the stacker and sheet guide 8 again.

For this reason, this printer includes a platen 5
A first and a second pair of paper feed rollers 3 and 10 are disposed on the back side and the near side of the sheet feeder.
As shown by a solid line and a two-dot chain line in FIG. 3, is mounted at the same height as the nip portion of the second paper feed roller pair 10 and at a position one step lower than the position where stacking is possible.

FIGS. 1 to 3 show a second paper feed roller pair 10 to which a paper detection sensor is attached.
The paper feed roller pair 10 is disposed at a position corresponding to the lower drive roller 12 and a lower drive roller 12 fixed at a distance to a lower drive shaft 11 supported by a side frame (not shown). The upper drive roller 15 is provided.

The upper drive roller 15 is mounted on a C-shaped mounting portion 13a at the free end of a swing arm 13 about a shaft 17 fixed to a side frame (not shown), and is attached to the swing arm 13. Acting biasing spring 14
And is pressed against the lower drive roller 12. An upper drive roller shaft 16 passes through the center of the upper drive roller 15, and a joint 31 that transmits power from the upper drive roller shaft 16 is provided on a side surface of the upper drive roller 15. Furthermore, the hole diameter of the upper drive roller 15 and the outer diameter of the upper drive roller shaft 16 are set so as to have a gap, and slips p have entered between the lower drive roller 12 and the upper drive roller 15. Sometimes, the upper drive roller 15 is displaced together with the swing arm 13, and even in that state, the joint 31 is displaced.
Is configured to transmit power.

An upper paper guide 30 for guiding slips p to the upper drive roller 15 is provided around the upper drive roller 15, and the upper paper guide 30 is positioned on the shaft 17 and the upper drive roller shaft 16. Does not move. The upper drive roller 15 in the paper detection area of the upper paper guide 30
The detector holder 21 is fixed to one of the mutual gaps. Here, a detector 2 composed of a light emitting element and a light receiving element
So that 0 positions these elements axially,
These elements are mounted so as to have a fixed inclination angle θ, preferably 30 °, on the nip portion A side with respect to the paper surface.

On the other hand, a reflection plate holder 24 having a C-shaped cross section is fitted into a portion corresponding to the paper detector 20 between the lower drive rollers 12 fixed to the lower drive shaft 11 at intervals. A reflection plate 23 provided on a part of the paper guide plate 6 is held at the focal position of the detector 20, and an engagement recess 25 provided on a part of the reflection plate holder 24 is provided on the paper guide plate 6 extending from the platen 5. The reflecting plate 23 is engaged with the concave portion 7.
Is positioned correctly in the axial direction so that the surface of the paper has a tilt angle θ with respect to the paper surface, in other words, the paper detector 20 faces the paper detector 20 at right angles.

In FIG. 4, reference numeral 9 denotes a carriage that scans the carried recording head 4 in a direction perpendicular to the paper conveying direction.

In the embodiment configured as described above, in order to perform recording and writing on continuous paper or cut-sheet paper, first, the stacker and sheet guide 8 is pushed down to the stack position shown by the two-dot chain line, and then pushed. The tractor 1 or the paper feed roller 2 is operated to feed the continuous paper or cut sheet to the printing unit, where necessary recording and writing is performed, and then the paper is discharged from the second paper feed roller pair 10 onto the stacker / sheet guide 8. .

On the other hand, when printing on postcards and slips, first, the stacker / sheet guide 8 is held at the same height as the nip portion A of the second pair of paper feed rollers 10, and The slips p are manually inserted along the surface of the sheet guide 8.

As a result, the leading end of the slips p enters the detection area of the paper detection sensor immediately before the second paper feed roller pair 10, but as described above, this paper detection sensor uses the second paper feed roller pair. 10, the reflecting plate 23 provided in the vicinity of the stacker / sheet guide 8 side is inclined with respect to the paper surface and
0, the paper detection sensor accurately detects the passage of the slips p based on a large difference in the reflectance between the reflector 23 and the slips p. Based on the detection signal, the paper feed motor (not shown) is rotated in the reverse direction, the slips p are sent to the recording / writing section to perform the required recording / writing, and then the paper feed motor is switched to the normal rotation.
After the recording and writing are completed, the slips p are discharged onto the stacker / sheet guide 8.

As the evaluation paper, black, gray, and white paper having a glossy coating on the surface are used, and the inclination angle θ of the reflection plate is variously changed with respect to these papers. FIG. 5 (a) shows the result obtained by extracting the change in the output of the current from the optical detector arranged opposite to the reflection plate.
The results as shown in (c) were obtained.

Therefore, the inclination angle θ of the reflection plate is set to 30 °.
It became clear that the output could be reduced to 乃至 to ／ when set near.

[0020]

As described above, according to the present invention, since the reflection plate of the reflection type optical paper detector is provided so as to be inclined with respect to the paper conveyance surface, the reflection light from the paper surface is directly received. By avoiding this, it is possible to determine the presence or absence of a sheet with a small detection output, so that the detection margin can be further increased.

In addition, the paper detection sensor can be disposed closer to the nip portion of the paper feed roller by arranging the reflection plate obliquely with respect to the paper surface. The sequence control mechanism for feeding the paper and recording / writing can be greatly simplified.

Further, since the reflecting plate and the detector are directly mounted on the shaft of the paper feed roller, the mounting angle and the mounting position in the axial direction with respect to the paper surface can be reduced by a simpler mechanism and a simpler assembling operation. Can be performed more reliably.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a paper detection sensor according to an embodiment of the present invention in relation to a paper feed mechanism.

FIG. 2 is a top view of the detection sensor and a paper feeding mechanism.

FIG. 3 is a front view of a main part of the above.

FIG. 4 is a diagram showing a schematic configuration of a printer including the detection sensor according to the first embodiment.

FIGS. 5A to 5C are diagrams showing a relationship between an angle of a reflection surface with respect to a paper surface and a detection output when black, gray, and white papers are detected;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Push tractor 2 Paper feed roller 5 Platen 8 Stacker and sheet guide 10 Second paper feed roller pair 20 Detector 21 Detector holder 23 Reflector 24 Reflector holder p Paper

Claims (5)

(57) [Claims] 1. A paper detection sensor for a printer, comprising a reflector disposed on one side and an optical detector comprising a light-emitting element and a light-receiving element facing each other with a paper transport path interposed therebetween. And a light receiving element are arranged at an interval in a direction orthogonal to the sheet conveying direction, and the reflection plate is
A paper detection sensor for a printer, wherein the light from the light emitting element is arranged obliquely to the light receiving element at a position close to the nip portion of the paper feed roller and is incident on the paper receiving direction. . 2. The reflection surface is at an angle of 30 ° with respect to the paper transport direction.
2. A sheet detection sensor according to claim 1, wherein said reflection plate is disposed so as to be inclined so as to form an angle. 3. The sheet detection sensor according to claim 1, wherein the reflection plate is located at a focal position of the detector. 4. A sheet detection sensor according to claim 1, wherein said reflection plate is mounted on a shaft of one of the rollers forming a paper feed roller pair. 5. The paper detection sensor according to claim 1, wherein said detector is mounted with reference to the axis of one of the rollers forming the paper feed roller pair.