JPH04366706A - Medium detector - Google Patents

Abstract

PURPOSE:To obtain a medium detector of a high S-N ratio and generating no error detection, as to a medium detector used for detecting the position of a paper-form medium being conveyed, and the like. CONSTITUTION:A medium detector 31 furnishes a luminous element 32, a curving member 33, and a light receiving element 34. The luminous element 32 and the light receiving element 34 are provided on the same surface at one side of a medium passage, while the curving member 33 is provided at the other side of the medium passage at the position opposite to the luminous element 32 and the light receiving element 34. The output light which has been output from the luminous element 32 and crossed almost square to the medium passage is converted the angle about 180 deg. by the curving member 33, and output by crossing the medium passage at the position different from the initial output light. The light receiving element 34 receives the output light and generates an output according to the intensity of the light.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medium detector used for detecting the position of a paper-like medium being conveyed.

[0002]In information output devices such as printers, copying machines, and facsimile machines that use paper-like media, it is necessary to detect accurate positions of various media. At this time, particularly when using preprinted paper such as a slip or when printing from corner to corner of a predetermined paper, accurate paper position detection and high line feed accuracy are required. This requirement is also important from the standpoint of global environmental protection, which aims to reduce the size of the media and save resources.

0003

2. Description of the Related Art Various conventional medium detectors are shown in FIGS. Their structure and function are as follows.

The medium detector 1 shown in FIG. 5 is of a light reflection type and includes a light emitting element 2 and a light receiving element 3. The medium detector 1 shown in FIG. In this medium detector 1, the light emitted from the light emitting element 1 is reflected on the surface of the medium 100, the reflected light is received by the light receiving element 3, and the presence or absence of the medium is detected by a change in the amount of reflected light.

The medium detector 11 shown in FIG. 6 is of a transmitted light type, in which the light emitted from the light emitting element 12 that has passed through the medium 100 is detected by the light receiving element 13, and the medium detector 11 detects the light transmitted through the medium 100 based on the change in the amount of detected light. Detect the presence or absence of.

Furthermore, the medium detector 21 shown in FIG. 7 is of a detection type using a mechanical lever, and the leading edge of the incoming medium 100 is deformed as shown in the figure by engagement with the lever 22. By detecting the rotation of the lever 22 that receives the biasing force (using a micro switch, etc.),
Media is detected.

[0007]

[Problems to be Solved by the Invention] However, each of these conventional systems has the following drawbacks. In the medium detector 1 of FIG. 5, the output of the light-receiving element changes depending on the color of the medium surface and the thickness of the medium, so detection accuracy decreases, and in extreme cases, erroneous detection occurs due to insufficient S/N ratio. Further, in the medium detector 11 shown in FIG. 6, the output varies depending on the material and thickness of the medium, so detection accuracy decreases, and in extreme cases, erroneous detection occurs due to insufficient S/N ratio. however,
Generally, the performance is better than that of the system shown in FIG. Furthermore, Figure 7
In the medium detector 21, the amount of deformation of the medium changes depending on the material and thickness of the medium, and the detection position changes. With thin paper, etc., the amount of deformation increases, and medium conveyance defects such as jams are likely to occur.

An object of the present invention is to provide a medium detector with a high signal-to-noise ratio and no false detection.

[0009]

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a medium detector for detecting the position of a medium traveling through a medium path, the medium detector being disposed along the medium path; a light emitting element that generates light substantially perpendicular to the light emitting element; and a light emitting element that emits light that is substantially perpendicular to the light emitting element, and a light emitting element that emits light that is emitted from the light emitting element and crosses the medium path. A structure characterized by comprising a bending means for changing the direction and position of light, and a light receiving element that receives the light emitted from the bending means across the medium path and outputs an output according to the intensity of the light. (first configuration).

Further, in the medium detector according to claim 1, the bending means is constituted by one bending part, and the light emitting element and the light receiving element are arranged on the same side and on the same plane with respect to the medium path. This is a characteristic configuration (second configuration).

Further, in the medium detector according to claim 1, the bending means is constituted by a plurality of bending parts so that the number of times the light passes through the medium passage is three or more times, and A configuration (third configuration) characterized in that the emitted light passes through the medium path at different positions.

Further, in the medium detector according to claim 2 or 3, the position of each passing light that exits from the light emitting element and the bending means and passes through the medium path is determined with respect to the traveling direction of the medium traveling through the medium path. A configuration (fourth configuration) is characterized in that they are arranged vertically.

Further, in the medium detector according to claim 2 or 3, the position of each passing light that exits from the light emitting element and the bending means and passes through the medium path is determined with respect to the traveling direction of the medium traveling through the medium path. A configuration (fifth configuration) is characterized in that they are arranged in parallel.

[0014]

[Operation] When the medium reaches the medium detector, a portion of the light emitted from the light emitting element is blocked by the medium, and a portion of the light is transmitted through the medium. This transmitted light is reflected and refracted at the bending portion of the bending means, and is partly blocked again at a position different from the incident light on the medium, and partly is transmitted. The amount of light that has finally passed through the medium in this way is converted into an electrical signal by the light receiving element. By repeating the transmission in this way, the signal-to-noise ratio is improved, the detection reliability is improved, and at the same time, the detection accuracy is also improved.

In particular, in the case of the second configuration, since the light emitting element and the light receiving element are on the same surface, the electrical wiring becomes simple and the mounting cost is reduced. In addition, in the case of the fourth configuration, it is possible to improve the detection accuracy of the leading position of the medium and to detect the position of the side edge surface of the medium, and in the case of the fifth configuration, the positions of multiple leading edges of the medium can be detected. Detectable.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a perspective view showing the outline of a medium detector 31 according to this embodiment. We are prepared. The light emitting element 32 and the light receiving element 34 are connected to the medium 1
Support member 3 disposed below the medium passage through which 00 passes.
5, they are arranged in parallel in the direction perpendicular to the medium running direction and are located on the same plane. The bent portion 33 is provided above the medium path and faces the light emitting element 32 and the light receiving element 34.

The light emitted from the light emitting element 32 is partially blocked by the medium 100 and partially transmitted through the medium 100. This transmitted light is reflected and refracted at the bending part 33 as shown by the arrow, and is partially blocked again at a position different from the incident light on the medium 100.
A portion of the light passes through the medium 100 and heads toward the light receiving element 34 . The amount of light finally transmitted through the medium 100 is measured by the light receiving element 34.
convert it into an electrical signal.

As described above, the ratio (transmittance) of transmitted light passing through the medium 100 varies greatly depending on the material and thickness of the medium, but according to the method of this example, it is said to have the highest precision conventionally. It has higher precision than a transmission type detector because it can obtain an output equal to the square of the transmittance. Specifically, for example, the transmittance of very thin Japanese paper is approximately 70%, and the S of a conventional transmission type detector is
The N ratio (no paper ÷ paper present) is 1 ÷ 0.7, which is S in this example method.
The N ratio is 1÷0.7×0.7=1÷0.49, and the detection reliability and detection accuracy are improved at the same time. Also,
In this example method, unlike the conventional reflective type method shown in FIG. 2, the light-emitting element 32 and the light-receiving element 34 are arranged on the same surface, which simplifies the electrical wiring and reduces the mounting cost.

[0020] By arranging a plurality of bent portions above and below the medium path and increasing the number of times that light passes through the medium to three or more times, not only will the S/N ratio be further improved, but also it will be possible to prevent errors even with perforated paper. Does not cause detection. Figure 2 explains this method. Figure 2 (A) shows perforated paper 100A, Figure 2 (B
) respectively indicate the detection procedure for this paper 100A.

Furthermore, as shown in FIG. 3A, if the positions of the plurality of medium-transmitted light beams (indicated by x marks) are arranged perpendicularly to the medium running direction, the leading edge of the medium
The detection accuracy is improved, and the position of the side end surface of the medium can be detected. Further, as shown in FIG. 3(B), if the positions of the plurality of medium-transmitted light beams (indicated by x marks) are arranged parallel to the medium running direction, the positions of the plurality of leading edges of the medium can be detected.

FIG. 4 shows another method of detection by the medium detector. In the case of this figure, the light that enters the medium 100 from the light emitting element 41 is slightly oblique (almost perpendicular), passes through the medium 100, and is changed by an angle of approximately 180 degrees by the bending part (bending means) 42 to the light receiving element 43. incident on . In this case, the light reflected by the dotted line on the paper does not enter the light receiving element 43.

[0023]

[Effects of the Invention] As described above, according to the present invention, S
It becomes possible to improve the N ratio and prevent false detection. Further, when the light emitting element and the light receiving element are arranged on the same surface, the electrical wiring becomes simple and the mounting cost becomes low. Furthermore, if multiple bends are placed above and below the media path to increase the number of times the light passes through the media to three or more times, not only will the signal-to-noise ratio further improve, but it will also prevent false detection even with perforated paper. There isn't.

Furthermore, by arranging the positions of a plurality of light beams transmitted through the medium perpendicular to the medium running direction, it is possible to improve the detection accuracy of the leading edge of the medium and to detect the position of the side edge surface of the medium. By arranging the positions of the light transmitted through the medium in parallel, it is possible to detect the positions of a plurality of leading edges of the medium.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an outline of a medium detector according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a perforated paper detection method according to an embodiment of the present invention, in which FIG. 2(A) shows a perforated paper, and FIG. 2(B) shows a method for detecting this perforated paper.

3A and 3B are explanatory views of various arrangements of light transmitted through a medium according to an embodiment of the present invention. FIG. B) shows a case where the positions of a plurality of light beams transmitted through the medium are arranged parallel to the medium running direction.

FIG. 4 is an explanatory diagram of another detection procedure according to the embodiment of the present invention.

FIG. 5 is a perspective view showing an outline of a conventional medium detector.

FIG. 6 is a perspective view showing an outline of another conventional medium detector.

FIG. 7 is a perspective view showing an outline of another conventional medium detector.

[Explanation of symbols]

31 Medium detector 32, 41 Light emitting element 33, 42 Bending part 34, 43 Photo receiving element

Claims (5)

[Claims] 1. A medium detector for detecting the position of a medium traveling through a medium path, comprising: a light emitting element disposed along the medium path and generating light substantially perpendicular to the medium path; and the light emitting element bending means for changing the direction and position of the emitted light so that it crosses the medium path at a different position from the emitted light by changing an angle of approximately 180 degrees; and from the bending means. A medium detector comprising a light receiving element that receives light emitted across the medium path and outputs an output according to the intensity of the light. 2. The medium detector according to claim 1, comprising:
A medium detector characterized in that the bending means is constituted by one bending part, and the light emitting element and the light receiving element are arranged on the same side and on the same plane with respect to the medium path. 3. The medium detector according to claim 1, comprising:
The bending means is configured with a plurality of bending parts so that the number of times the light passes through the medium passage is three or more times, and the light emitted from each bending part passes through the medium passage at a different position. A medium detector characterized by: 4. In the medium detector according to claim 2 or 3, the position of each passing light beam exiting from the light emitting element and the bending means and passing through the medium path is determined with respect to the traveling direction of the medium passing through the medium path. A medium detector characterized by being arranged vertically. 5. In the medium detector according to claim 2 or 3, the position of each passing light beam exiting from the light emitting element and the bending means and passing through the medium path is determined with respect to the traveling direction of the medium traveling through the medium path. A medium detector characterized in that the medium detectors are arranged in parallel.