JPS61161069A - Sheet scanner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a sheet scanner, and more particularly, the present invention relates to a sheet scanner, and more particularly, a sheet original moved by a feed roller is passed from a slit-shaped reading section provided at a fixed position to a one-dimensional sensor array through an optical system. The present invention relates to a skew correction sheet scanner that forms an image and reads it.

[Prior art]

The configuration of this type of conventional sheet scanner is shown in Figure 5 and @
This will be explained with reference to FIG. A document 1 placed on a document table 2 is guided by a movable document guide plate 3 and conveyed by a feed roller 4 . Next, the original 1 is exposed to a light source (
The light is transmitted to a one-dimensional sensor array (COD) 10 and read through an optical system consisting of a fluorescent lamp 7, a mirror 8, and a lens 9. Reference numeral 11 indicates a document sensor, and 12 indicates a document sensor. The document width sensor 12 is connected to a document sensor board (photo interrupter) 13 as shown in FIG.
, and a senna shutter 1 facing the board.
4 are provided.

In the above configuration, if the document 1 is skewed when it is bitten by the feed roller 4, this skew will continue, and if the crimping force of the feed roller 4 is different between the left and right sides, the skew amount will gradually increase. The disadvantage is that it increases.

In order to prevent this document skew, it is necessary to manually bring the document guide plate 3 of the document table 2 into close contact with the end surface of the document 1. This method uses the automatic document feeder (
It is difficult to read a document without skew when sending it using an ADF (ADF), and when performing "partial scanning" in which a part of the document is specified and only that area is read, it is difficult to read the document without skew. Even if there is a skinny image, it is impossible to use a conventional sheet scanner because it will cause deviation from the designated area.

〔the purpose〕

The present invention was made in view of the drawbacks of the above-mentioned conventional devices.
It is an object of the present invention to provide a sheet scanner that can correct skew even when a document is inserted obliquely, and can also correct and remove a slight skew during reading.

〔composition〕

In order to achieve the above object, the present invention disposes a pressure plate with a higher reflectance than a blank original on the back side of the reading slit, is equipped with a circuit that sequentially detects the position of one edge or both edges of the original, and moves the left and right feed rollers. When the document is separated into two pairs, and the deviation of the document side edge position in the sub-scanning direction exceeds the allowable value, the rotational speed of the six pairs of feed rollers is made different to prevent the document side edge position deviation and, as a result, the document skew. It is characterized by adjusting the A detailed description will be given below based on one embodiment of the present invention. In the drawings, parts that are the same as or corresponding to those of the conventional apparatus shown in FIGS. 5 and 6 will be described with the same reference numerals.

FIGS. 1(α) and 1(A) show the main parts of an embodiment of the present invention in a partial cross-sectional view and a partial plan view.
The document 1 placed thereon is conveyed by a feed roller 4, and as is clear from the plan view in Figure <b>, this feed roller 4 has two pairs of left and right feed rollers 4α, 4A and 4A arranged at a distance from each other. It has 4c and 4cL. Feedrow 24α, 4b and 4c, 4cL
A slit-shaped reading section 6, that is, a reading slit, is provided between the sheets in the sheet feeding direction, and a pressure plate 5 is disposed on the back surface thereof.

The light from this reading slit 6 passes through an optical system consisting of a light source 7, a mirror 8, and a lens 9 to a one-dimensional sensor array 10.
It is imaged and read.

As shown in FIG. 2, the pressure plate 5 of the reading section is made of a material having a higher reflectance than the white background of the original, that is, made of a transparent material such as glass and has a reflective film 5α. 8 may be tilted so that light from a light source 7, for example, a fluorescent lamp, is directly guided to the reading sensor 10, or a longitudinal light source such as a fluorescent display tube may be used for the pressure plate 5. If you do this, Figure 3 (b1~(
As shown in d+, the sensor output outside the middle of the document is higher than that even if the document is white, so the side edge position of the document must be detected from this sensor output using a comparator or the like in units of sensor pixel density. I can do it. If the document is even slightly skinny, this side edge position will also move as the document is fed. When this amount of movement exceeds a certain value, a skew occurrence detection signal is output from the detection circuit. In addition, in Figure 3, (α) shows the video output in the prior art, (b) shows the video output when no document is detected in the present invention, and (C1 shows the video output when a blank original is read in the present invention). , and (d) shows a video output when reading a general document according to the present invention.

Next, the circuit used in the present invention will be explained. Fourth
In the figure, the signal from the clock generator 20 is supplied to the sensor array (COD) 10 on the one hand, and the C0DIO
The output is sent via a video amplifier 27 to an A/D converter 28 to an image signal processing section. On the other hand, the signal from the clock generator 20 is sent to the document side edge detection circuit 22 through the main scanning counter 21 . This document side edge detection circuit 22
A part of the output of the A/D converter 28 is supplied to the A/D converter 28, and the output of the document side edge detection circuit 22 is supplied directly to the ALU 24 on the one hand and to the ALL 124 via the side edge holding register 23 on the other hand. The output from this ALU 24 is compared with the output from the constant setting 25 in a comparator 26, and the output from the comparator 26 is supplied directly or via an OR gate 29 to an electromagnetic clutch 30, that is, a clutch for each feed roller. . In the figure, 30z is a clutch for the right roller 4a, 30b is a clutch for the left roller 4b, and 30C
is the clutch for the right roller 4C, and 3Qd is the clutch for the left roller 4c.
This is an L clutch. 'When a signal is applied to the electromagnetic clutch 30, the driving force of the step motor (not shown) is cut off and is no longer transmitted to the rollers.

As described above, the present invention includes at least one set of feed rollers that are divided into left and right sides and driven separately, and during the skew correction operation, the direction in which the sheet travels is corrected by changing the rotational speed of the left and right rollers. To explain this in more detail, the main motor (not shown) has two sets of rotational forces.

2 on the left and right, 4 in total, 4cL, 4b, 4C, 4cL in the diagram
The skew correction detected by the skew detection circuit described above is transmitted through the electromagnetic clutches 30 that can be turned on and off separately to the feed rollers, that is, the respective roller clutches 30 (L, 304, 30C, and 304). Feed rollers 4α, 4b,
All feed roller drive electromagnetic clutches 30α, 30b except one of 4c, 4cL, for example 4d-
, 30C are turned off, only the feed roller 4d drives the sheet, and the other rollers 4α, 4b, and 4c become driven rollers that merely hold the sheet.
Sheet skew is corrected. When it is detected that the document side edge position has returned to its original position due to this skew correction,
The skew correction operation instruction signal is turned off, and the four sets of feed rollers 4α, 4h.

All rollers 4c and 4d are restored as driving rollers and continue reading.

In the above embodiment, the rotational force of the feed roller is controlled on/off using a solenoid, but other methods are also possible, such as providing a drive motor for each roller and making a difference in their rotational speed during skew correction operation. A correction operation may also be performed (1°Also, the above embodiment has been described as a sheet scanner, especially a sheet scanner in a facsimile machine, but an intelligent image input device K4)
Can be used for IJ.

According to the above embodiment, since the feed rollers can be driven independently at four locations, skew correction can be performed more accurately.

〔effect〕

As described above, according to the present invention, a pressure plate having a higher reflectance than a blank original is arranged on the back side of the reading slit, and a detection circuit is provided to sequentially detect the position of one end or both ends of the original.
In addition, the feed rollers are separated into two pairs on the left and right, so
Even if the original is on a white background, the sensor output will be higher than that, making it easier to detect skew and correcting the original skew more accurately. A sheet scanner with a simple configuration can be provided.

[Brief explanation of drawings]

FIG. 1(α)t(b) is a partial sectional view and a partial plan view showing the configuration of the sheet scanner of the present invention, FIG. 2 is a schematic explanatory view showing the document width detection mechanism used in the present invention,
Figure 3 (αl, (b), (C), fd+ is a characteristic diagram showing the video output when reading the original, respectively.
The figure is a circuit diagram showing a skew detection circuit used in the present invention, and FIGS. 5 and 6 are schematic configuration diagrams illustrating a conventional device. 1...Manuscript, 4α, 4b, 4c, 4d...
...Feed roller, 5...Press plate, 6...
...Reading slit, 7...Light source, 8...
...Mirror, 9...Lens, 10...
One-dimensional sensor array, 22...document side edge detection circuit, 30...electromagnetic clutch. Figure 4 Figure 5

Claims (3)

[Claims] (1) A sheet original is moved by a feed roller,
In a sheet scanner that scans images from a slit-shaped reading unit installed at a fixed position through an optical system onto a one-dimensional sensor array, a pressure plate with a higher reflectance than a white original is placed behind the reading slit, and one edge of the original is scanned. or a detection circuit that sequentially detects the positions of both side edges, and separates the feed rollers into two left and right pairs, and when the deviation of the document side edge positions in the sub-scanning direction exceeds a permissible value, rotation of each pair of feed rollers is provided. A sheet scanner that adjusts document skew by correcting the deviation of the document side edge position by providing a difference in the number of documents. (2) The sheet scanner according to claim 1, wherein the pressure plate comprises a longitudinal light source such as an LED array or a fluorescent display tube. (3) A mechanism is provided for releasing a pair of original transport rollers other than the left and right separation feed rollers from motor drive during a skew adjustment operation.
Sheet scanner described in ).