JPS6127275A - Paper end detector for printer - Google Patents

Abstract

PURPOSE:To greatly enhance the capability of detecting a paper end and contrive a smaller printer, by a construction wherein a transparent plate having a different refractive index part at a position corresponding to the boundary between a light-emitting part and a light-receiving part of a reflection-type photo-sensor is provided directly above the sensor. CONSTITUTION:The reflection-type photo-sensor 5 provided on the lower side of a recording paper comprises the light-emitting part 5a and the light-receiving part 5b, and a transparent sensor cover 9 is provided thereon. A thin plate 9a provided in the cover 9 at a position corresponding to the boundary 5c between the part 5a and the part 5b is formed of a material different from that for the other part of the cover 9, and has a refractive index different from that of the other part, so that light is substantially totally reflected at this part, and light is prevented from entering the light-receiving part in the absence of the recording paper. The thin plate 9a may be formed of a material which perfectly shields light. Paper dust adhered to the cover 9 is removed by the end of the paper, and can not enter into the surface of the sensor 5. Accordingly, malfunctions can be prevented from occurring due to reflection of light at the surface of the dusting sensor cover, and sensitivity in paper end detection can be enhanced. In addition, since the reflection-type photo-sensor can be placed at the side of a small diameter press roller, the depth of the printer can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to thermal printers, wire dot printers,
The present invention relates to a paper edge detection device for a printing device used in various printing devices such as type wheel printers.

Conventional configurations and their problems In recent years, printing apparatuses have been increasingly commercialized into personal computers, portable terminals, and the like, and there has been an increasing demand for smaller and lighter printing apparatuses. By devising the paper end detection device of such a printing device, it is possible to contribute to meeting the above requirements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A conventional paper edge detection device for a printing device will be described below with reference to the drawings. FIG. 1 shows a paper end detection device for a printing device using a conventional reflective optical sensor. In the figure,
1 is a paper feed roller, 2 is a recording paper, 3 is a pressure roller, and 4 is a print head for printing on the recording paper 2. 6 is a reflective optical sensor that detects the paper edge.

The operation of the paper edge detection device of the printing device configured as described above will be described below. Printing is performed on the recording paper 2 held by the paper feed roller 1 and the pressure roller 3 by the action of the print head 4 . When one line of printing is finished, the paper feed row 21 rotates, the recording paper 2 is sequentially fed, and a new paper surface comes in front of the print head 4. When the recording paper 2 is in front of the reflective optical sensor 6 as shown in FIG. It can be determined that there is, but
As shown in FIG. 3, the recording paper 2 is
When the paper edge 2a passes through, the light emitted from the second light emitting section 6a is:
Even if the light can be reflected at the paper edge 2a, it cannot enter the light receiving section 5b, so a change appears in the output electrical signal, and it can be determined that the recording paper 2 has run out. Furthermore, we were able to create a safety device that would prevent the print head 4 from operating even if a print signal was received.

However, in the above configuration, it is necessary to arrange the reflective optical sensor 6 next to the large-diameter paper feed row 21, which has the disadvantage that the depth of the printing device becomes large. This has been a big problem at a time when portable printing devices are in demand.

Therefore, as shown in FIG. 4, the pressure roller 3 is placed below the recording paper 2.
Printing devices in which a reflective optical sensor 5 is placed next to a printer have started to appear. However, the configuration shown in FIG. 4 has the drawback that paper dust inevitably generated from the recording paper 2 adheres to the light emitting and light receiving surfaces of the reflective optical sensor 5, which causes the sensor to malfunction if used for a long time. Therefore, the reflective optical sensor 6
In order to protect the sensor from paper dust, a sensor cover 6 made of transparent resin was added as shown in Figure 5.
Even when there is no recording paper 2 on the reflective optical sensor 6, a part of the light emitted from the light emitting part 6a is constantly reflected on the surface of the sensor cover 6 and enters the light receiving part 6b, which generates electricity for paper edge detection. Not only is it difficult to set the circuit constants, but it can also lead to malfunctions.

OBJECTS OF THE INVENTION The present invention provides a paper edge detection device for a printing device that can greatly improve the paper edge detection ability of a printing device in which a reflective optical sensor is disposed below the recording paper, and can also reduce the size of the printing device. The purpose is to provide the following.

Structure of the Invention In order to achieve the above-mentioned object, the paper edge detection device of the printing device of the present invention includes a paper end detection device of the present invention, which is provided with a paper edge detection device that is installed near the boundary between the light emitting portion and the light receiving portion of the reflective photosensor, directly above the reflective photosensor facing the recording paper. This configuration includes a transparent plate having portions that differ in refraction. With this configuration, the reflective optical sensor can be protected from paper dust and can operate stably.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The configuration of the present invention is basically the same as the configuration based on FIG. 4 used in the description of the conventional example, and a reflective light cell 6 is disposed below the recording paper 2.

FIG. 6 shows an enlarged sectional view of the reflective optical sensor.

6 is a reflection type optical sensor, which includes a light emitting part 6a and a light receiving part 6.
b, and 6C is the boundary between the two. 7 is a transparent sensor cover, and a slit 7a is provided above the boundary portion 6C. Since the sensor cover 7 is provided with the pickpocket door a, the path of light that was conventionally reflected on the surface of the sensor cover 7 is changed, and no light enters the light receiving section 6b. 7th
The figure shows a case where recording paper 2 is present. A portion of the light emitted from the light emitting section 6a is emitted from the surface of the recording paper 2 and enters the light receiving section 6b. Therefore, depending on the presence or absence of the recording paper 2, the light receiving section 6
Since there is a large difference in the light entering b, it becomes easy to design the constants of the electric circuit for paper-detection, and malfunctions do not occur. It should be noted that paper dust adhering to the sensor cover 7 does not pose a problem for detection because the edge of the paper removes it.

FIG. 8 shows another embodiment of the paper edge detection device of the present invention.

8 is a transparent sensor cover, and four parts 8a such as triangular grooves are provided on the boundary part 6C. The purpose of this is to ensure that paper dust never enters the surface of the reflective optical sensor 5.

FIG. 9 shows yet another embodiment. 9 is a transparent sensor cover, and 9a is a thin plate made of a different material. Since different materials have different refractive indexes, the light undergoes almost total internal reflection, and when there is no recording paper 2.

Prevents light from entering the light receiving section 6b. Further, the material of the thin plate 9a may be a material that does not transmit any light at all.

Effects of the Invention As is clear from the above explanation, the present invention provides a method of refraction that differs in the vicinity of the boundary between the light emitting part and the light receiving part of the reflective photosensor, directly above the reflective photosensor disposed below the recording paper. The structure includes a transparent plate with a part that prevents malfunctions due to light reflection on the surface of the sensor cover for paper powder protection.
Paper edge detection sensitivity can be increased. Further, since the reflective optical sensor can be placed next to the pressure roller having a small diameter, an excellent effect can be obtained in that the size of the printing device in the depth direction can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a side view of the main part showing a paper end detection device of a conventional printing device, Figs. 2 and 3 are cross-sectional views of the reflective optical sensor portion for explaining the operation of the conventional example, and Fig. 4 is FIG. 5 is a sectional view of the reflection type optical sensor portion of another conventional paper edge detection device, and FIG. 6 is a reflection of the paper edge detection device of a printing device according to an embodiment of the present invention. Cross-sectional view of the type optical sensor part, No. 7
The figure is a sectional view for explaining its operation, and FIGS. 8 and 9 are sectional views showing other embodiments. 1...paper feed roller, 2...recording paper,
3... Pressure roller, 4... Print head,
6... Reflective optical sensor, 6a... Light emitting part, 6b... Light receiving part, 6C... Boundary part,
6.7.8.9... Transparent plate, 7a... Hole, 8a... Triangular groove, 9 &... Thin plate. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure? Figure 4 Figure 6 Figure 7?

Claims (4)

[Claims] (1) A reflective optical sensor is placed below the recording paper, and a refraction sensor is placed directly above the reflective optical sensor facing the recording paper, and a refraction sensor is placed near the boundary between the light emitting part and the light receiving part of the reflective optical sensor. A paper edge detection device for a printing device equipped with a transparent plate having a portion that (2) A paper edge detection device for a printing device according to claim 1, characterized in that a slit is provided near the boundary between the light emitting part and the light receiving part of the reflective optical sensor of the transparent plate. (3) A paper edge detection device for a printing device according to claim 1, wherein a recess is provided near the boundary between the light emitting part and the light receiving part of the reflective optical sensor of the transparent plate. (4) A paper edge detection device for a printing device according to claim 1, characterized in that a thin plate made of a different material is provided near the boundary between the light emitting part and the light receiving part of the reflective optical sensor made of a transparent plate. .