JPH0415661B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image scanning device for reading original images.

When scanning an image using a solid-state scanning element, light is irradiated onto the document surface, the reflected light is imaged on a solid-state scanning element such as a CCD, and this is electronically scanned in a direction perpendicular to the main scanning direction. A method of performing sub-scanning is generally used. Scanning is performed over the entire area of a certain scanning area. An example is shown in FIG. L is an exposure lamp, 1 is a solid-state scanning element, 2 is a lens, 3 is an original table, and 4 is an original.

In this type of image scanning, conventionally, if the original is smaller than a specified size or is not set in the specified position on the original reading table, unnecessary parts other than the original may be printed, or part of the image may be printed on the recording material. There was a problem with the print protruding from the paper. In order to eliminate such problems, it is necessary to detect the position of the document 4, that is, detect the document portion and the non-document portion, and control the printer accordingly. Until now, little consideration has been given to this point.

The present invention has been made in consideration of the above points, and
A document table 5 on which a document is placed, and reading means 1 and 2 that read the document image by main-scanning the document placed on the document table and sub-scanning the document in a direction perpendicular to the main scanning direction. , detecting the leading edge and the trailing edge of the document in the main scanning direction based on the output signal of the reading means, and detecting the front edge and the trailing edge of the document in the main scanning direction from the start of the main scanning, respectively. First counting means C1 and C2 output first and second pixel counts, and detect the leading edge and trailing edge of the document in the sub-scanning direction based on the output signals of the reading means, and start sub-scanning. second counting means L1 and L2 for outputting third and fourth pixel count numbers until detecting the leading edge and trailing edge of the document in the sub-scanning direction, respectively; First and second pixel counts corresponding to the front edge and rear edge of the document in the main scanning direction, respectively, and the front edge and rear edge of the document in the sub-scanning direction output from the second counting means, respectively. a discriminating means 11 for discriminating the document size or document placement position based on the third and fourth pixel counts corresponding to the first and second pixel counts; The present invention provides an image scanning device having an extraction means 10 for extracting an image signal representing an image.

The present invention will be explained below with reference to the drawings.

FIG. 2 shows an embodiment of the invention using two solid-state scanning elements. L is an exposure lamp, 1 and 2 are solid-state scanning elements, 3 and 4 are lenses, 5 is an original table, and 6
is the original placed on the original table 5. The solid-state scanning elements 1 and 2 scan in the directions of arrows D and E, respectively, toward the center. When scanning a document, cover the document with a black document cover on the side that contacts the document, or leave the document cover open. When scanning is performed in this state, the light from the exposure lamp L is reflected only on the original part, and the parts other than the original 6 are detected as black level, and the position of the original is detected by detecting the ground color of the original 6, for example, the white level. can.

FIG. 3 shows a method of detecting the document position. Reference numeral 5 indicates a document table, 6 indicates a document portion, and 7 indicates a portion other than the document.
P ₁ is the sub-scanning start point, and P ₂ is the sub-scanning end point.
It is also assumed that the total number of pixels in the main scan (n bits) and the total number of pixels in the sub scan (m bits) are known in advance. Second
When the document is scanned from _P1 as shown in the figure, the solid-state scanning elements 1 and 2 detect the black level until the white level of the document is detected. In this way, the number L of pixels in the sub-scanning direction (L ₁ bit) and the number of pixels C ₍₁ bit) in the main scanning direction are stored when the solid-state scanning element 1 detects the white level for the first time during document scanning. It also stores the number of pixels _C2 in the main scanning direction when the solid-state scanning element 2 detects the white level for the first time. Similarly, the number of pixels _L2 bits until the end of the document is stored. on the other hand,
Image information read by scanning is stored in an image memory. When reading image information from this image memory, the number of bits mentioned above is
By addressing and reading the image memory according to C ₁ , C ₂ , L ₁ , and L ₂ and printing it out, it is possible to extract image information of only the document portion from the image memory.

Embodiments of the present invention will be described in detail below with reference to FIGS. 4 and 5.

FIG. 4 shows a block diagram of the present invention. Reference numerals 1 and 2 denote solid-state scanning elements whose main scanning directions are in the directions of arrows D and E, respectively, as shown in the figure. 13 is a clock generator which is inputted to the solid-state scanning elements 1 and 2 and the counter of the CPU 11. 14 and 15 are A/D converters, 16 and 17 are registers for temporarily storing image information, 8 is a readout control unit that reads out the contents of registers 16 and 17, and 9 is divided and stored in registers 16 and 17, respectively. 10 is an image memory that can store the entire scanning area; 11 is a gate control unit that converts the data being scanned into serial image information for one scan;
Document position count using CPU with ROM and RAM
It is capable of counting and storing C ₁ , C ₂ , L ₁ , and L ₂ , and also has an address function for the image memory 10 . C ₁ and C ₂ are counters that can count at least n/2 bits, and L ₁ and L ₂ are counters that can count at least m bits. 12
The laser unit prints out the contents of the 10 image memories onto a recording material. First, the image information scanned by the solid-state scanning elements 1 and 2 is sent to the A/D converter 14 by the clock of the clock generator 13.
15, A/D converted by A/D converters 14 and 15, and stored in registers 16 and 17. At this time, the CPU 11 counts document position counts C ₁ , C ₂ , L ₁ , and L ₂ obtained by the method shown in FIG. Note that the contents of the register 17 are read out by the read control section 8 in the reverse order of input to the register, and the contents of the register 16 are read out in the same order as input. The contents of 16 and 17 are read out as serial one-scan image information by switching the gate control section 9, and are sequentially stored in the image memory 10.
is stored in

FIG. 5 is an address map of the image memory 10 of FIG. When the image memory 10 is assigned addresses from (0,0) to (m,n) as shown in FIG. 5, the position coordinates of the document input to the image memory 10 are the four points a, b, and c,
d. Here, 20 is an image memory, and 21 is a document image stored in the image memory 20. Therefore, the CPU 1 is configured to output only the document portion to the laser unit 12 of the printer.
1 to address. At this time, if the printer scans in the long side direction, (L ₁ , C ₁ ) → (L ₂ , C ₁ )
Scan the image information in the image memory 10 as follows, and if it is in the short side direction, (L ₁ , C ₁ ) → (L ₁ ,
By scanning as shown in (n- _C2 ), only the image information of the document stored in the image memory 11 is read out, and unnecessary data can be removed.

In this embodiment, a case where two solid-state scanning elements are used has been described, but the present invention can be similarly applied to a case where three or more solid-state scanning elements are used.

FIG. 6 shows an example in which three solid-state scanning elements are used. 31, 32, 33 are solid state scanning elements;
4, 35, and 36 are lenses, 5 is an original table, and 6 is an original placed on the original table 5. In this case, for example, the solid-state scanning elements 3 are arranged so that the scanning direction of the solid-state scanning elements arranged at both ends of the three solid-state scanning elements is the center.
Only the scanning direction of 1 is in the direction of arrow E, the others are respectively F,
This can be achieved by setting it in the G direction.

Further, the color of the document cover is not limited to black, and the present invention can be similarly applied by using a color that makes the reading signal discontinuous at the boundary between the document and the document cover when the document is white.

As explained above, according to the present invention, the reading means for reading the original image does not require a sensor dedicated to size or position detection, and the original is not placed in alignment with the reference position on the original table. Based on the output signal, it is possible to determine the size or placement position of the document placed at any position on the document table, and therefore it is possible to reliably extract an image signal representing the document image from the output signal of the reading means. .

[Brief explanation of drawings]

Figure 1 shows an example of conventional document scanning, Figure 2 shows an example of conventional document scanning.
Figure 3 shows an example of the scanning method according to the present invention.
The figure shows a method for detecting the document position according to the present invention.
FIG. 4 is a block diagram showing a circuit configuration according to the present invention, FIG. 5 is a diagram showing an address map of the image memory in FIG. 4, and FIG. 6 is a diagram showing another embodiment. A scanning element, 6 a document, 10 an image memory, and 11 a CPU.

Claims (1)

[Scope of Claims] 1. A document table on which a document is placed, and a document image is read by main-scanning the document placed on the document table and sub-scanning it in a direction perpendicular to the main-scanning direction. a reading means; detecting a front end and a rear end of the original in the main scanning direction based on an output signal of the reading means, and detecting each of the front end and the rear end of the original in the main scanning direction from the start of the main scanning; a first counting means for outputting first and second pixel counts up to the start of the sub-scanning; and a first counting means for outputting the first and second pixel counts until the start of the sub-scanning. a second counting means for outputting third and fourth pixel counts from 1 to 10 until detecting each of the leading edge and trailing edge of the document in the sub-scanning direction; first and second pixel counts corresponding to the front edge and rear edge of the document, respectively, and corresponding to the front edge and rear edge of the document, respectively, in the sub-scanning direction output from the second counting means; a determining means for determining the document size or the document placement position based on the third and fourth pixel counts; and an image signal representing the document image from the output signal of the reading means according to the determination result of the determining means. An image scanning device comprising: extraction means for extracting.