JP2002326740A - Duplicate sending detecting device in image recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double feed detecting device in a recording device, which can detect double feed of paper sheets without impairing recording speed as much as possible without making paper sheets wasteful. SOLUTION: In the double feed detecting device in the recording device, which is provided with a device to feed and transfer paper sheets one by one from a plurality of paper sheets placed piled up, a means to detect one end of a paper sheet on which recording is made ahead of another paper sheet on which recording is made in the image recording device, and a means (comprising a light projection section 111 and a light sensor 112) to detect a paper sheet other than the paper sheets on the side of the recording face of the paper sheet on which recording is made in the image recording device are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double feed detecting device in an image recording apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a printer having a transport path for transporting a sheet cut to a predetermined size, one sheet is fed from a sheet feeder or a sheet feed tray.
An image is formed on the paper by being transported one by one. If a double feed occurs in which two or more papers are transported in a state of being overlapped at this time, the double-fed paper is transferred to the paper in the transport path. This may cause a jam or a situation in which blank paper is mixed in the paper after image formation, and a desired output result cannot be finally obtained at the recording speed originally provided by the recording apparatus. Therefore, this type of apparatus is often provided with a double feed detecting device for detecting double feed of sheets.

In general, a double feed detecting device detects the thickness of a sheet by a sensor for detecting the thickness of the sheet in a sheet conveyance path (a transmission type photo sensor, a sensor using a swing arm, or the like) and sets the thickness of the sheet in advance. Double feed is detected by comparing with the value.

However, the method of comparing the detected sheet thickness with a preset value makes it difficult to deal with various types of sheets having different sheet thicknesses and different thicknesses. For this reason, for example, in Japanese Patent Application Laid-Open No. Hei 3-192050, a sensor for detecting the thickness of a sheet is provided in the conveyance path, and the sensor detects the thickness of the nth sheet after feeding and sets the data in advance. A multi-feed detecting apparatus for detecting a multi-feed of sheets by multiplying the value by a predetermined value and comparing this value with the sheet thickness data of the (n + 1) -th sheet has been proposed.

[0005] As an improvement of the above apparatus, Japanese Patent Application Laid-Open No.
In Japanese Patent No. 116101, a sensor for detecting the thickness of a sheet is provided in a conveyance path, and the average value of the sheet thickness data after sheet feeding detected by the sensor and the sheet thickness fed so far is calculated.
A method of detecting a double feed by comparing the two is disclosed.

[0006]

However, in the technique proposed in the above-mentioned Japanese Patent Application Laid-Open No. 3-192050,
The multi-feed of the (n + 1) th sheet is detected by multiplying the sheet thickness data of the (n) th sheet after feeding by a predetermined value set in advance and comparing this value with the sheet thickness data of the (n + 1) th sheet. Therefore, there is a problem that it is not possible to detect the double feeding of the first conveyed sheet after the sheet is fed.

Further, in the technique disclosed in Japanese Patent Application Laid-Open No. 11-116101, although the detection accuracy of the double feed is improved, a state in which blank paper is mixed in the paper is caused in the final output result.

In order to solve the above problem, it has been proposed that one or more sheets are automatically conveyed after the sheet feeding tray is set, and a double feed of the next sheet to be conveyed is detected using this as a reference value. However, the paper automatically conveyed is wasted.

If the paper automatically conveyed to obtain the comparison of the reference values has already been multi-fed, the subsequent multi-feed detection cannot be performed normally.

[0010] The present invention has been made in view of the above problems, and the object thereof is to avoid wasting paper,
An object of the present invention is to provide a double feed detecting device in a printing apparatus capable of detecting a double feed without impairing the recording speed as much as possible.

[0011]

In order to achieve the above-mentioned object, the present invention provides a method for reducing the number of sheets placed on a plurality of sheets.
A double feed detecting device in an image recording apparatus having a device for feeding and conveying each sheet, means for detecting a sheet edge on which recording is performed ahead of a sheet on which recording is performed in the image recording apparatus, and recording is performed in the image recording apparatus. A means for detecting a sheet other than the sheet on the recording surface side of the sheet to be read.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing a paper feeding section and an ink printing section of an image recording apparatus. In this embodiment, the configuration of an ink jet recording apparatus will be described.

In FIG. 1, reference numeral 101 denotes a print head for printing, and the print head 101 slides in a direction perpendicular to the paper surface to print on a print paper 103. Reference numeral 102 denotes an ASF (Auto Sheet Feeder) on which recording paper is stacked, and reference numeral 103 denotes a cut recording paper. 104 is a registration roller,
Reference numeral 105 denotes a transport roller, reference numeral 106 denotes a paper discharge roller, and reference numeral 107 denotes a platen. Reference numeral 111 denotes a light emitting unit having a built-in LED,
Reference numeral 112 denotes a sensor unit having a built-in photo sensor.

The recording paper 103 loaded on the ASF 102 is fed one by one by a pickup roller (not shown) and conveyed to a registration roller 104. At the registration roller 104, the leading end of the recording paper 103 abuts,
The recording paper 1 is temporarily set so that the obliqueness of the recording paper 103 is eliminated.
No rotation is performed to send 03. The registration is adjusted at the registration roller 104 and the registration roller 1 is adjusted.
04 starts rotation, and the recording paper 103
Due to the rotation of 04, the light is conveyed between the light projecting unit 111 and the sensor unit 112 while blocking the light of the LED. Recording paper 103
At a short time abuts the transport roller 105 and is transported by the transport roller 105.

According to the printing method, the recording paper 103 is stopped at a predetermined position on the platen 107 every time, and the recording head 101 performs printing.

While the conveyance of the recording paper 103 is stopped and the printing of the recording head 101 is repeated, the recorded image is recorded on the recording paper 103.
Form on top. In addition, the recording paper 103 is
While the printing is being performed by 6, the sheet is conveyed in synchronization with the conveying roller 105. When the recording is completed, the sheet discharging roller 106 rotates to discharge the recording sheet 103.

The recording paper 103 loaded on the ASF 102 in the above-described configuration is fed by a pickup roller. At this time, the recording paper 103 loaded on the top on which printing is performed is performed.
3 and the recording paper 103 immediately below it may not be properly separated but two or more sheets may originally be fed. In addition, although the separation is successful, the recording sheet 103 immediately below may start moving while the first recording sheet 103 is being fed. The above is collectively called double feed,
In many cases, separation is not successful, and two recording papers are fed almost overlapped with each other, and the first or second paper is fed first.

FIG. 2 is a diagram showing the relationship between the light projecting unit 111, the sensor unit 112, and the recording paper 203 described with reference to FIG. The recording paper 103 includes the LED 201 and the photo sensor 20.
2, the presence or absence of the recording paper 103 is detected by intercepting the light emitted from the LED 201, and at the same time, the output of the photo sensor 202 is monitored to determine whether or not the recording paper 103 passing therethrough has a double feed. Is also detected.

FIG. 3 is a diagram showing the output signal of the photosensor 202 in the case where there is no normal double feed in accordance with the conveyance of the recording paper 103 on the determined recording paper 103.
The portion 301 of the signal is when the recording paper 101 is not present, that is, L
The case where all the light of the ED 201 is received by the photo sensor 202, and the portion of the
1 shows a state in which light from 1 is blocked, that is, a state in which the recording paper 103 is sent between the LED 201 and the photo sensor 202 for conveyance. Here, when the recording paper 103 passing between the LED 201 and the photo sensor 202 is double fed, the output of the photo sensor 202 has a different signal waveform from that shown in FIG.

FIGS. 4A to 4C show the state of the recording paper 103 and the output signal shown in FIG. 3 when a double feed that passes through the double feed detecting unit in FIG. 2 described above occurs. FIG.

FIG. 4A shows a state in which the recording paper 401 stacked one sheet below the recording paper 402 to be fed is first conveyed for some reason. I have. FIG. 4B shows a state in which, contrary to FIG. 4A, the recording paper 401 stacked below that of the recording paper 402 to be originally recorded is conveyed with a delay.
FIG. 4C shows a state in which the recording paper 401 and the recording paper 402 are simultaneously fed and conveyed without being separated well. Here, in the state shown in FIG. 4A, the recording paper 401 blocks the light of the LED 201, and the output signal is 30
It shifts to the level from 1 to 303.

However, the LED 20 on the recording paper 401
Since the recording paper 402 is conveyed to the first side along with the recording paper 401, the output signal once drops to the level of 404, and eventually becomes the output signal 403 when two recording papers shield the LED 201 from light. At this time, the recording paper 402
Is located on the LED 201 side, the recording paper 4
The output signal is temporarily 4 due to the irregular reflection from the tip of 02
04 level. In the state shown in FIG. 4B, first, the recording paper 402 blocks the light of the LED 201, and the output signal shifts from the level of 301 to 303.

However, since the recording paper 401 is conveyed to the photosensor 202 side of the recording paper 402 in accordance with the recording paper 402, the output signal is eventually changed to LE by two recording papers.
The output signal 403 is obtained when D201 is shielded from light. Further, in the state shown in FIG.
Since the leading end of 02 is completely overlapped, the output signal is from 301 when there is no recording paper to 403 when the LED 201 is shielded by two recording papers.

As shown in FIG. 2, when printing is performed when paper is fed without normal double feeding, the recording paper is conveyed by a predetermined amount by detecting the leading edge thereof and is moved to a predetermined position on the platen 107. The printing is stopped and printing is started by the recording head 101.

In the state shown in FIG.
When printing is performed by detecting the leading edge of the recording paper 402, one page of the recorded image is printed on both of the recording papers 401 and 402, and the page cannot be used. When printing is started by transporting a predetermined amount from 404 as the leading edge signal of the recording paper 402 and printing is started, the entire page is recorded on the recording paper 402.

In the state shown in FIG. 4B, the leading edge of the recording paper 402, that is, the output signal 405 of the photo sensor 202 is used as the leading edge signal of the recording paper 402, and a predetermined amount is conveyed therefrom to start printing. 4C, similarly, in the state shown in FIG. 4C, the leading edge of the recording paper 402, 401, that is, the output signal 405 of the photosensor 202, and the recording paper 401, 402.
It is only necessary to convey a predetermined amount as the leading edge signal of the above and start printing.

With the above-described configuration, even if there is a double feed, all the images to be output are printed, although there is mixing of blank paper, and printing is performed without wasting recording paper. There is no need to redo some.

Although the double feed of two sheets has been described above, when the number of sheets is larger than that, when the output of the sensor becomes a certain value or less, even if the sheet is conveyed, it cannot be conveyed on the way, causing a jam or a recording head. It is desirable to stop by a paper feed error or the like because the head rubs against the recording paper during sliding and damages the head.

Of course, the level of the output signal changes depending on the type of recording paper, and the judgment level also changes, but these can be solved by the conventional method.

[0031]

As is apparent from the above description, according to the present invention, there is provided a double feed detecting device in an image recording apparatus having a device for feeding and conveying one sheet at a time from a plurality of stacked sheets. A means for detecting a paper edge on which recording is performed ahead of a paper on which image recording is performed; and a means for detecting paper other than the paper on the recording surface side of the paper on which recording is performed in the image recording apparatus. Therefore, it is possible to obtain a public charge that a double feed can be detected without wasting paper and reducing recording speed as much as possible.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a sheet feeding unit and an stamping unit of an image recording apparatus.

FIG. 2 is a diagram illustrating a double feed detection unit.

FIG. 3 is a diagram illustrating an output signal from a double feed detection unit.

FIG. 4 is a diagram illustrating a form of double feeding and an output signal when double feeding occurs.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Recording head 102 ASF 103 Stacked recording paper 111 Light emitting part 112 Sensor part 201 LED 202 Photosensor 401, 402 Recording paper

Claims (1)

[Claims] 1. One of a plurality of sheets placed one on top of the other
A double feed detection device in an image recording apparatus having a device for feeding and conveying each sheet, means for detecting a sheet edge on which recording is performed ahead of a sheet on which recording is performed in the image recording apparatus, and recording in the image recording apparatus. A double feed detecting device in an image recording apparatus, further comprising means for detecting a sheet other than the sheet on the recording surface side of the sheet to be read.