JPH0822006B2 - Document reader - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a document reading device that reads a document image, converts it into an electric signal, and outputs it as an image signal.

[Prior art]

Conventionally, in this type of document reading apparatus, those which detect the position and size of the document on the document table have been proposed, but these devices detect only the maximum width of the document in the vertical and horizontal directions, and thereby the rectangular shape is detected. It was to define the area. Therefore, if control such as extraction of the original image is performed based on this, information outside the original is also output as original information when the original is licked even when outputting the image signal only within the original. There was a drawback that it would end up.

[Object] The present invention has been made in view of the above points, and in an original reading device that reads an original image, converts it into an electric signal, and outputs it as an image signal, the image signal representing the original image includes information outside the original. For the purpose of surely extracting the image without any problem, in detail, an image pickup means for scanning the document table on which the document is placed in the main scanning direction, and a moving means for moving the main scanning position of the image pickup means in the sub scanning direction. And a recognition means for recognizing the coordinates of four points of maximum and minimum distances in the main scanning and sub-scanning directions of the document based on the signal output from the imaging means during the recognition scan, and the recognition means for outputting from the imaging means during the main scan. On the basis of the received signal, the detection for detecting the leading edge and the trailing edge of the document in the main scanning direction within the area defined by the coordinates of the four points recognized by the recognition means for each main scanning Document reading having means for extracting the image signal between the front edge and the rear edge of the original detected by the detecting means for each main scan from the image signal output from the image pickup means during the main scan A device is provided.

〔Example〕

 Hereinafter, the present invention will be described according to examples.

FIG. 1 is a schematic diagram of a document reading apparatus 1 (hereinafter referred to as a reader) embodying the present invention. An image pickup device 203 such as a CCD is used to read image information of a document 202 placed on a document table 201 and pressed by a document cover 210.
The illumination light from 4 is reflected on the surface of the original 202, and the mirrors 205, 20
An image is formed on the image sensor 203 by the lens 208 via 6,207. The light source 204, the mirror 205, and the mirrors 206 and 207 are configured to move at a relative speed of 2: 1. This optical unit moves from left to right at a constant speed while being PLL controlled by the DC servo motor 209.

While the optical unit is moving, the optical scanning unit moves forward from the left end to the right end while reading the main scanning line orthogonal to the sub-scanning direction Y line by line with the image sensor at a resolution of 400dot / inch, and then returns to the left end again. Then, one scan is completed.

FIG. 2 is a block diagram showing an example of the internal structure of the reader.

The optical lens 208 is used for document image O placed on a document table (not shown).
It is used to image the RG onto the CCD 203. The original image is sequentially scanned line by line by an optical system (not shown).
Since such a reading technique is a well-known technique, detailed description will be omitted.

The CCD 203 converts the light and shade of the original image into an electric signal, and the CCD drive circuit 300 outputs the electric signal as an image signal. This electric signal is amplified by an amplifier circuit 301, and an analog / digital converter (A / D converter) 302 multivalues (2
It is converted to a digital signal of 8 bits in decimal.

Further, the digital signal is subjected to shading correction circuit 303 to remove shading caused by light emission unevenness of the light source, uneven light intensity distribution of the optical system, uneven sensitivity of CCD, etc., and then input to the gate circuit 304. The gate circuit 304 is a circuit for outputting an image signal, and its control is performed by a microcomputer described later.

The image signal passed through the gate circuit 304 is a density correction circuit 306.
Then, the variation of the input characteristics is corrected and the density is corrected so that the image is output at a desired density, and the image signal is output to a recording device such as a printer or a computer.

In addition, the signal passed through the shading correction circuit 303 is
The document is input to the document detection circuit 305 to detect the document on the document table 201. The document detection circuit 305 detects a signal level change point by comparing a digital signal obtained by reading the entire surface of the document table 201 with the density on the back side of the document cover 210. The maximum and minimum of the main scanning and the sub scanning are detected. Is composed of a part for recognizing the distance from the origin and a part for detecting the maximum and minimum positions of one line, and the position information is sent to the microcomputer (CPU 310) via a CPU bus described later.

The image signal that has passed through the gate circuit 304 is input to the peak detection circuit 307 to detect the peaks of the white information value and the black information value on the document. The detected value is also sent to the CPU31 via the CPU bus.
Sent to 0. The CPU 310 determines the correction data of the density correction circuit based on the value.

Microcomputer (CPU) 310 operates by the control program written in ROM 311, RAM312, I / O port
315, a timer circuit 316, a serial circuit 317 for communicating various information with other devices, and a key display drive circuit 313 are used to control the entire reader.

Next, the document detection and image output system will be described with reference to FIG.

First, in this embodiment, the image signal is output by the reciprocating operation of the optical unit twice. Original as shown in FIG. 3 (A)
When 202 is placed obliquely on the original table 201 (hatched portion in the figure), the original detection circuit 305 is moved by one reciprocating movement of the optical system.
Information of four points (x ₁ , y ₁ ), (x ₂ , y ₂ ), (x ₃ , y ₃ ), and (x ₄ , y ₄ ) in the figure is stored in. In the present embodiment, in order to prevent erroneous detection, the case where the same data continues for 8 lines or 8 pixels is valid.

When each point from (x ₁ , y ₁ ) to (x ₄ , y ₄ ) is recognized by the _first round trip of the optical system (hereinafter referred to as recognition scan), the coordinate information is notified to the CPU 310. In this recognition scan, the image signal is not output to an external device such as a printer. Then, the second skiyan (called the real skiyan) is performed subsequently. A schematic diagram of an image signal output by this scanning is shown in FIG. 3 (B). In this embodiment, the output image portion is calculated for every 8 lines based on the document detection information in the main scanning direction of the preceding line, and the gate circuit 304 is controlled according to the value to control the output of image information in the document. .

That is, when scanning is performed up to y ₂ obtained in FIG. 3 (A), the gate circuit 304 is turned off and the image signal is not output. Thereafter, the document detection circuit 305 performs a document recognition operation in the main scanning direction for each line from y ₂ .
Capture the recognition data of the last 1 line for every 8 lines,
The gate position is calculated and gate information is set in the gate circuit 304. The gate position is calculated by the position information from (x ₁ , y ₁ ) to (x ₄ , y ₄ ) recognized by the recognition scan, the recognition information of the immediately preceding one line and the previous recognition information, and increase / decrease the position information. I do. Then, the image signal is output as shown by the solid line in FIG. (In FIG. 3 (b), the dotted line indicates the original, and the dashed-dotted line indicates the area defined based on the recognition at the time of the recognition scan.) Note that the origin of the recognition information of one line (see FIG. 3 (A)). The _one closer to the point) is xp ₁ and the _one farther from the origin is xp ₂ .

Next, referring to FIG. 4 and FIG.
The operation of the CPU 310 will be described.

If there is a read request from the operation unit (not shown) (ST
P401), operate the motor 209 (STP402), and perform recognition scan. The reciprocating control of the motor 209 is performed by counting the number of encoder pulses generated from the motor shaft.

When the recognition scan is completed (STP403), the document recognition data is loaded from the document detection circuit (STP404). At this point, the CPU 310 recognizes the coordinate data of the four points shown in FIG.

Next, operate the drive motor for this scan (STP4
05). Then, the gate circuit 304 is closed until the optical unit reaches the position of the point y _{2 at} the left end of the coordinates (STP406, STP407).
If the position of y ₂ is reached, 1 line of document recognition data xp
₁ and xp ₂ are fetched from the document detection circuit 305 (STP408), and the gate position is calculated (STP409). The calculation method will be described in detail with reference to FIG. The gate data determined by the calculation is set in the gate circuit 304 (STP410). Then, the peak value for AE is fetched from the peak detection circuit 307 (STP411),
The density correction data is calculated (STP412), and the density correction data is set in the correction circuit 306 (STP413). From the document recognition data load up to this point to the density correction data set (STP408 to ST
The process up to P413) is performed within the time period for outputting the image signal for one line.

Then, the optical unit moves and waits until the signal output for 8 lines is completed (STP414), and it is judged whether the optical unit has reached the final position y ₃ in the Y direction (STP415). Do the operation again. When the optical unit reaches the position of y ₃ , that is, when the output of the image data in the document is completed, the gate circuit 304 is closed and the optical unit is returned to the home position (STP416).

FIG. 5 shows a detailed explanation of the calculation of the gate position (STP409 in FIG. 4). As gate data, two points, a point near the origin (image output start point) and a point far from the origin (image output stop point) are calculated and set in the gate circuit 304.

Therefore, first, the calculation of the image output start point is performed. The recognition capture data xp ₁ is the lower limit value x ₁ of the recognition data in the x direction.
It is judged whether it is smaller, and if it is smaller, it is an erroneous recognition, so the previous gate data is used (STP501, STP506).

On the other hand, if there is no misrecognition, it is judged immediately after the sub-scan exceeds y ₁ which is the point closest to the origin in the X direction (main scanning direction),
If it exceeds, the image area will be inside and the final point (x ₃ )
A value obtained by dividing the difference of x ₁ by the number of change points (distance) in the sub-scanning direction,
That is, the gate data is added with the increment (STP502, STP50
6).

If it is not immediately after the change point y ₁ exceeds the sub-scanning direction, it is compared with the previous recognition data (STP503). If it is larger than the previous recognition data, the difference from the previous recognition data is added from the current recognition data and the gate is added. Data (STP504).

On the other hand, if it is smaller than the previous recognition data, the current recognition data is used as the gate data (STP505).

Next, the recognition data xp ₂ farther from the origin is compared with the maximum point data (x ₄ , y ₄ ) in the main scanning direction in the same manner as described above, and the same processing is performed to determine the gate data (STP5
07, STP508, STP509, STP510, STP511, STP512, STP513).

As described above, first, the placement position of the document 202 on the document table 201 is recognized as a four-point coordinate by the recognition scan, and the recognition position is used to detect the document position of each line in the scan scan. It is possible to accurately output only the image signal corresponding to the original document to an external device such as a printer by gating the image signal from the.

Further, the data obtained by the recognition scan can determine the correctness of the recognition data in this scan, and can also achieve good position detection.

Although the present embodiment is designed to output the image signal with the maximum width, if the image signal is output with a certain margin on the inside of the paper, the image is output outside the original even if the original is non-rectangular. It is possible to prevent the output of image information.

As described above, in the document reading apparatus, after detecting the maximum lengths in the horizontal and vertical directions, the document is sequentially detected within the range, and the image signal is output only within the range of the document. Even if erroneous recognition is made by sequential detection, it is possible to eliminate erroneous recognition by comparing with the maximum length.

Also, by detecting the maximum length, it is possible to easily realize selection of output paper such as a printer and automatic scaling to designated paper.

Further, by detecting the maximum point in the main scanning direction and taking into account the calculation of the difference from the final point immediately after passing, it becomes possible to suppress the output of image signals other than the original.

[Effect]

As described above, according to the present invention, the coordinates of the four points of the maximum and minimum distances in the main scanning direction and the sub-scanning direction of the document are recognized during the recognition scan, and within the area defined by the recognized coordinates of the four points. Since the front edge and the rear edge of the document in the main scanning direction are detected for each main scan during the main scan, and the image signal between the detected front edge and the rear edge of the document is extracted for each main scan, any document table It is possible to reliably extract the image signal representing the original image of the original of any shape placed at the position without including the information outside the original.

[Brief description of drawings]

FIG. 1 is an internal structure diagram of the document reading device of this embodiment, FIG. 2 is an internal circuit diagram of the document reading device, FIG. 3 is a schematic explanatory view of this embodiment, and FIGS. 4 and 5 are micro computers. Is an operation flow chart of No. 201, a document table 201, a document 202, a CCD 203, a gate circuit 304, and a document detection circuit 305.

Claims (1)

[Claims] 1. An image pickup device for scanning a document table on which a document is placed in a main scanning direction, a moving device for moving a main scanning position of the image pickup device in a sub scanning direction, and an output from the image pickup device during recognition scanning. The recognition means for recognizing the coordinates of the four points of maximum and minimum distances in the main scanning and sub-scanning directions of the document based on the generated signal, and the recognition means based on the signal output from the imaging means during the main scan. From the image signal output from the image pickup unit during the main scan, the detecting unit detecting the front end and the rear end of the document in the main scanning direction within the area defined by the coordinates of the four points recognized by An original reading device comprising: an extracting unit that extracts an image signal between the front edge and the rear edge of the original detected by the detecting unit for each main scanning.