JPH05270699A - Paper conveying device - Google Patents

Abstract

PURPOSE:To surely detect a duplicate-conveying state and prevent a stain and damage of a recording medium by applying black coating to a paper guide surface of an image reading device to measure a white level value by means of an image sensor, or by measuring time of the recording medium passing through an image reading position to compare it with a reference value. CONSTITUTION:A surface of a paper guide 7 is coated with a black color. When a conveyed recording medium 10 is a single sheet, a part of light from a light source 2 is transmitted through the recording medium 10, reflected by a black color surface of the paper guide 7, and reaches a lens array 3 to lower a voltage level of a white part. When two sheets of the recording mediums 10 are conveyed in duplication, quantity of light reflected by the paper guide 7 becomes small to increase the white level value. A duplicate conveying state can be detected by measuring the white level value of an image sensor 4 in this manner. The duplicate conveying state cart be also detected based on the time from passing of a forward end of the recording medium 10 through an image reading position to passing of a rear end thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device used in an image reading device.

[0002]

2. Description of the Related Art A conventional sheet conveying apparatus used for an image reading apparatus is designed to feed a recording medium (recording sheet) on which image information is written and then apply a brake to only one side of a conveying roller. By shifting one of the two overlapping recording sheets and checking the length of the recording sheet being conveyed in the middle of conveyance, so-called double feeding in which the two recording sheets are conveyed in an overlapping state is detected. .

[0003]

In the conventional sheet conveying device as described above, one of the two overlapping recording sheets is mechanically displaced, so that the recording medium may be soiled or damaged. It has the drawback.

Further, when the recording medium is conveyed, the recording medium may skew, so that a mechanism for correcting the skew is necessary. If this skew correcting mechanism is provided, after the recording medium is started to be fed out. It also has a drawback that it takes a long time to finish discharging.

[0005]

SUMMARY OF THE INVENTION A sheet conveying device of the present invention comprises a paper guide whose surface is coated with black, and an image sensor which reads an image described on the surface of a recording medium conveyed on the paper guide. Which is configured to measure a white level value when the image on the recording medium is read by the image sensor,
Further, the time of the recording medium passing over the paper guide is measured and compared with a reference time.

[0006]

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

FIG. 1 is a side view showing an embodiment of the present invention.

In FIG. 1, the image reading unit 11 is
An image sensor 4 mounted on a substrate 5 with respect to a holder 1, a lens array 3, and a light source 2 arranged in front of and behind the lens array 3. The surface of the paper guide 7 is coated with black (black coating), and the running of the recording medium 10 is guided by guiding the running of the recording medium 10 between the dummy roller 6 and the dummy roller 6. It suppresses flapping. Recording medium 1
The conveyance of 0 is performed by holding the recording medium 10 between two sets of feed roller 8 and tension roller 9 provided before and after the image reading section 11 and rotating the feed roller 8.

To read the image written on the upper surface of the recording medium 10, the image that has come to the image reading position of the center line of the image sensor 4 and the lens array 3 is illuminated by the light source 2 from an oblique direction, and the reflected light thereof is reflected. Is imaged on the image sensor 4 by the lens array 3. At this time, when only one recording medium 10 is conveyed by the feed roller 8 and the tension roller 9, a part of the light from the light source 2 passes through the recording medium 10 and the black surface of the paper guide 7 is transmitted. Since the image data of the recording medium 10 is reflected by, reaches the lens array 3 again through the recording medium 10, the voltage level (white level value) of the white portion of the image data of the recording medium 10 becomes low due to so-called see-through. On the other hand, when the two recording media 10 are conveyed in an overlapping state, the amount of light that passes through the recording media 10 and is reflected from the paper guide 7 decreases, so that the white of the recording media 10 is reduced. The level value becomes higher.
Therefore, the double feeding can be detected by measuring the white level value in the image sensor 4.

On the other hand, the time from when the leading edge of the recording medium 10 passes the image reading position to when the trailing edge thereof passes is measured and compared with the time corresponding to the length of the recording medium 10 being conveyed. Thus, it is possible to detect whether or not the multi-feed state is set. In this case, when the two recording media 10 in the double-feed state are misaligned, it can be detected that they are in the double-feed state, but when the two recording media 10 are completely overlapped, the double-feed state is detected. Cannot be detected. For this reason, by using together with the detecting means for measuring the white level value described above, it is possible to detect any state of double feed. That is, when either one of the case where the white level value is high and the case where the length of the recording medium is longer than the reference value is detected, the multi-feed state is determined.

[0011]

As described above, in the paper transporting apparatus of the present invention, the surface of the paper guide provided at the image reading position is black-coated, and the white level value is measured by the image sensor. By measuring the time of the recording medium passing through the reading position and comparing it with a reference value, there is an effect that the double feeding state of the recording medium can be surely detected, and thereby, it is possible to prevent the recording medium from being soiled or damaged. effective.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

[Explanation of symbols]

 1 Holder 2 Light Source 3 Lens Array 4 Image Sensor 5 Substrate 6 Dummy Roller 7 Paper Guide 8 Feed Roller 9 Tension Roller 10 Recording Medium 11 Image Reading Section

Claims (2)

[Claims] 1. A paper guide, the surface of which is coated in black, and an image sensor for reading an image described on the surface of a recording medium conveyed on the paper guide. A paper conveyance device comprising: measuring a white level value when read by a sensor. 2. A paper guide, the surface of which is coated in black, and an image sensor which reads an image described on the surface of a recording medium conveyed on the paper guide, wherein the image on the recording medium is the image. A paper transporting device comprising: measuring a white level value when read by a sensor; and measuring a time of the recording medium passing on the paper guide and comparing the time with a reference time.