JPS60130256A - System for detecting original reading period - Google Patents

Abstract

PURPOSE:To eliminate the effect due to slip of an original by providing a light emitting element or a reflecting mirror making a direct light or a reflected light incident to an image sensor when no original exists at the original reading position. CONSTITUTION:The light of the light emitting element 40 is shut by an original 21 in the original reading period and only the reflecting light is inputted from an original plane to the image sensor 31. When the original 21 is not at the original reading position 29, the light of the light emitting element 40 is not shut by the original 21 but made incident to the image sensor 31. When the original 21 passes through the original reading position 29, since the light of the light emitting element 40 is shut, the level of an photoelectric converting output (a) is biased to the black level apart from the level 2 at all times and an output of an integration circuit 37 integrating an output (b) of a comparator 15 for one scanning period's share of the image sensor 31 rises when the tip of the original 21 reaches the reading position 29.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a document reading system of a facsimile machine and the like, and more particularly to (6) a method for detecting a document reading period using an image sensor.

Structure of a conventional example and its problems FIG. 1 is a schematic cross-sectional view of a document reading system of a conventional facsimile machine. In this figure, 1 is a document before it is read, 2 is a hopper in which the document 1 is stacked, 3 is a paper feed roller that feeds the document 1 one by one from the hopper 2 to the transport path 4, and 6 is the fed document. This is a photographing/feeding roller that conveys the image to the right on the conveyance path 4. 6 is a light emitting diode, and 7 is a light sensor facing the light emitting diode and the like via the conveyance path 4. Reference numeral 8 denotes a drive roller for sub-scanning feeding the document that has reached the document reading position @9; 1o a light source for illuminating the document reading position 9; 11 an image sensor for scanning and photoelectrically converting the document; 12 a document This is an image forming light guiding medium that forms an image on the image sensor 11 of the reflected light from the surface of the document at the reading position. 13
14 is a stacker for stacking the original document 13 that has been read. 15 and 16 are comparators, 17 is a counter, 18 is an output terminal for an image signal, and 19 is an output terminal for an original reading period signal.

In explaining the document reading operation, the document 1 is fed out to the conveyance path 4 by the paper feed roller 3, and is sent toward the document reading position 9 by the conveyance roller 6.

This document is stabilized by the driving pad roller 8.
The document is scanned by the image sensor 11vC when passing through the document reading position 9, and then discharged to the stacker 14. The photoelectric conversion output of the image sensor 11 is binarized into a black and white binary image signal by a comparator 16, and is sent to the outside from an output terminal 18.

The detection operation during the document reading period is as follows.

When the leading edge of the document reaches directly above the light emitting diode 6, the light from the light emitting diode 6 is blocked by the document and does not enter the optical sensor 7, and the output of the optical sensor 7 becomes high level. When the output of the optical sensor 7 reaches a high level, the output of the comparator 5 reaches a high level, the counter 17 starts, and each Ronilla 3, 5 .
The motor pulses supplied to the rotational drive pulse motor No. 8 are counted. When the count value reaches a predetermined value, the counter 17 resets its output document reading period signal to a high level and stops the counting operation.

When the document is further fed and its trailing edge passes directly above the light emitting diode 6, the output of the optical sensor 7 returns to a low level.
The output of comparator 15 becomes low level. Then, the counter 17 counts the number of motor pulses again, and when it reaches a predetermined value, sets the document reading period signal to a low level and resets it.

Here, the above predetermined value is selected to be equal to the number of motor pulses from when the leading edge or trailing edge of the original passes directly above the light emitting diode 6 until it reaches the original reading position 9.

Such conventional document reading period detection methods include the following method.

(1) It is extremely difficult to completely eliminate slip between the document and each roller 3, 5.8, and the amount of slip also varies depending on the paper quality and thickness of the document. Therefore, there will be a difference between the number of motor pulses from when the leading or trailing edge of the original passes directly above the light emitting diode 6 until it reaches the original reading position 9 and the above-mentioned predetermined value, depending on the paper quality of the original, etc. .

Since this difference appears as a detection error during the folded document reading period, high detection accuracy cannot be obtained.

(2) In order to reduce the above-mentioned slip, it is necessary to take mechanical measures such as installing a feed roller 5 between the paper feed roller 3 and the drive pad roller 8. This leads to complexity and enlargement.

Purpose of the Invention The present invention solves the above-mentioned conventional problems.It is possible to detect the document reading period with stability and high accuracy regardless of the paper quality of the document, and it is possible to simplify and downsize the document reading system. The purpose of this invention is to provide a method for detecting a document reading period.

Structure of the Invention The present invention provides a light emitting element or a reflective surface that allows direct light or reflected light to enter an image sensor for document scanning without being obstructed by the document only when the document is likely to be present at the document reading position. The image sensor is installed at the document reading position, and since the level of the photoelectric conversion output of the image sensor is far between the document reading period and other periods, by detecting the document l reading period, the influence of the slip of the document is essentially eliminated. The present invention also aims to alleviate the demands on the document transport mechanism and achieve the above-mentioned object.

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

FIG. 2 is a schematic cross-sectional view of a document reading system according to an embodiment of the present invention. In this figure, 21 is the original before reading, 22
is the hopper on which the original 21 is loaded, and 23 is the hopper 2
This is a feed roller that feeds out the originals 21 one by one from No. 2 and sends the originals to the No. 1 drive pad roller for sub-scanning feeding.

3o is a light source that illuminates the document reading position 29; 31 is an image sensor that scans and photoelectrically converts the document; and 32 is an image sensor 3 that converts light reflected from the document surface at the document reading position.
It is an image forming light guide medium that forms an image on 1. Reference numeral 33 denotes a read original document, and 34 a stacker on which the original document 33 is stacked. 35 and 36 are comparators, 37 is an integration circuit, 38
is the image output terminal, and 39 is the output of the original reading period signal ☆
There are 114 children.

4O is a light emitting element such as a light emitting diode for detecting the document reading period, and is provided directly below the document reading position 29. Note that instead of this light emitting element 4o, a reflective surface may be provided to reflect light from the light source 3O for illuminating the original.

FIG. 3 is an enlarged view of the driving pad roller 28 and the light emitting element 4O. As shown in this figure, in order to arrange the light emitting element 4○ directly below the document reading position, the drive 1
A circumferential groove 41 is formed in the center of the pad roller 28.

FIG. 4 is a waveform diagram for explaining the operation. The document reading operation and the document reading period detection operation will be described with reference to this figure.

First, the document reading operation will be explained. The document 21 is fed out one by one by the paper feed roller 23, and the drive pad roller 2
Sent in 8 inch. This document is sub-scanned and sent to the right side in the figure by the drive pad roller 28, and is finally sent to the stacker 34.
is discharged. The document is scanned by the image sensor 31 during the period when the document passes through the document reading position @29 (period T in FIG. 4).

During the period, that is, during the document reading period, the light emitting element 4
The light marked with ◯ is blocked by the document, and only the light reflected from the surface of the document is incident on the image sensor 31, so that the photoelectric conversion output 2L of the image sensor 31 has an external waveform as shown in FIG. This photoelectric conversion output a is binarized by a compensator 36 using level 1 (FIG. 4) as a slice level, and is sent to the outside from an output terminal 38 as an image signal Q, (1).

Next, the detection operation during the first reading of the original will be explained. During a period when the document is not at the document reading position 29, that is, in a period other than the document reading period T, the light from the light emitting element 4○ is incident on the image sensor 31 without being blocked by the document, so that the photoelectric conversion output of the image sensor 31 is The level in the effective section of each scan of a is closer to white than in the case of document scanning.

Since level 2, which is whiter than level 1, is set in the comparator 35 as the slice level, a rectangular waveform with the same period as the output of the comparator 35 (the scanning frequency jυ) is obtained during this period.

During the period when the original passes through the original reading position 29, that is, during the original reading period T, the light from the light emitting element 4O is blocked by the original and does not enter the image sensor 31.
The level of the photoelectric conversion output a is always closer to black than level 2.

Therefore, the output of the comparator 15 is set to 1 of the image sensor 31.
As shown in FIG. 4, the output of the integrating circuit 37, which integrates the scanning period, rises when the leading edge of the original reaches the original reading position 29, and as shown in FIG. It falls when the end passes through the document reading position 29 and retreats.

It is difficult to estimate the document reading period from the time when the document passes a position far from the document reading position 29.
The interval is detected as the document reading period.

Therefore, 1. Essentially, the slip of the original is the original reading I.
The detection between rJI does not lead to 19 degrees σ, and the calibration detection between document reading and IUI is always stable and highly accurate regardless of the paper quality and thickness of the document.

Since it is possible to tolerate a certain amount of slippage of the original during the general feeding of the original with the drive pad roller 28 inch, there is no need to provide a conventional transport roller (5), and the original is transferred to the drive pad using only the paper feed roller 23. It can be configured to be conveyed by rollers of 28 inches, and the mechanism of the document reading system can be simplified and downsized.

Furthermore, since the image sensor 31 for document scanning is used to detect the presence or absence of a document, there is no need to provide a separate optical sensor (7) for detecting the document reading period as in the conventional case. Contributes to simplification and cost reduction.

Although one embodiment of the present invention has been described above, the present invention is not limited thereto, and can be implemented with appropriate modifications. -1: The present invention -1. The present invention can also be applied to similar document reading systems other than facsimile machines.

Effects of the Invention As mentioned above, according to the present invention, it is possible to essentially eliminate the influence of the document sleeve, so it is always stable and consistent regardless of the thickness of the original paper material. It is possible to accurately detect the original reading interval IrJ1, and it is possible to eliminate the need for a conveyance roller that prevents the slippage of the original, and to achieve benefits such as rli, purification, and miniaturization of the original reading system mechanism.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a document reading system of a conventional Factor and S-Li apparatus, FIG. 2 is a schematic cross-sectional view of a document reading system according to embodiments of the present invention, and FIG. 3 is a light emitting element and drive pad. FIG. 4 is a schematic plan view showing an enlarged view of the roller, and FIG. 4 is a waveform diagram for explaining the operation. 21--Document before reading, 22--Hopper, 23-paper feed roller, 24--Conveyance path, 28--Drive pad roller, 30--Light source for document illumination, 31--Image sensor , 33... Read original document, 34. Stacker, 35. 36... Comparator, 37... Integrating circuit, 38 Image signal output terminal, 39... Original reading period signal output terminal. 4O...Light emitting element (Oshi only reflective surface)
. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] A means for generating and reflecting light is provided at the document reading position by the image sensor so that the light from the means is blocked by the document only when there is no document at the document reading device position. Place it so that it is incident on 7,
(d) A method for detecting a document reading period, characterized in that the document reading period is detected based on the difference in level between the photoelectric conversion output of the image sensor during the document reading period and other periods.