JP2860985B2 - Document reading device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an original reading apparatus, and more particularly, to an original reading apparatus having a variable magnification function.

2. Description of the Related Art As an output device of a document reading apparatus, for example, a CRT has a limited number of pixels that can be displayed in both the main scanning direction and the sub-scanning direction. In order to effectively use the limited area, the magnification must be arbitrarily set. On the other hand, in the conventional document reading apparatus, the magnification is changed in the main scanning direction by mechanically moving the imaging optical system to change the magnification to obtain a magnified image, or one of two dots of the original image data. There is a method of obtaining a scaled image by thinning out dots or overlapping one dot out of two dots. In the sub-scanning direction, the magnification is changed by changing the speed of the sub-scanning driving means. As a method, a stepping motor having many phases or a gear ratio is mechanically changed.

Problems to be Solved by the Invention However, according to the conventional configuration, there is a limit to the range in which the magnification is set in both the main scanning direction and the sub-scanning direction, and it cannot be said that the magnification is arbitrarily changed. In addition, when the magnification is changed, the gears of the imaging optical system and the sub-scanning driving means must be mechanically moved, so that the configuration is complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an original reading apparatus capable of performing arbitrary magnification with a simple configuration.

Means for Solving the Problems In order to achieve the above object, the present invention provides a photoelectric conversion element for photoelectrically reading an original, a sub-scanning driving means for relatively moving the photoelectric exchange element and the original, A / D converter that A / D converts the output of the conversion element, multiple line memories that store one or more lines of the original image data of this A / D converter, and scaling setting that sets an arbitrary scaling factor Means,
An operation of writing original image data to one line memory of the plurality of line memories, reading the original image data from the line memory to which the original image data has been written, and extracting three pixels from two adjacent pixels by the internal division method Writing control means for controlling the operation of creating the above pixel data and writing the interpolation data to another line memory, and reading for controlling reading of the line memory according to the magnification set by the magnification setting means Control means; and sub-scanning drive control means for controlling the sub-scanning drive means in accordance with the magnification set by the magnification setting means.

Operation The present invention is configured as described above. In the main scanning direction, the address is sequentially given to the line memory by the writing control means and the A /
One line of the original image data after the D conversion is stored, and the original image data is read from the line memory, and image data of three or more pixels is created from two adjacent pixels by the internal division method, and another line is formed. This interpolation data is stored in the memory. Thereafter, an address corresponding to the scaling factor is given to the line memory by the reading control means, and the scaled image data is obtained. The sub-scanning direction is PLL-controlled by the sub-scanning drive control means at a speed corresponding to the magnification, and the magnification is changed.

FIG. 1 is a block diagram of a document reading apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a document, and reference numeral 2 denotes an optical system unit for reading the document 1 photoelectrically, and includes a light source 2a, a lens 2b, and a photoelectric conversion element 2c. Reference numeral 3 denotes sub-scanning driving means for relatively moving the original 1 and the optical system unit 2, and reference numeral 3 denotes an A / D converter for converting the output of the photoelectric exchange element 2c from analog to digital. 4 is the first
5, a line memory capable of storing one or more lines of original image data output from the A / D converter, 6 an output device such as a CRT, 7 a second switching means, and 8 a line memory 5 Writing control means for controlling writing of data, 9
Is a magnification setting means for arbitrarily setting a magnification, and 10 is a line memory 5 according to the magnification set by the magnification setting means 7.
Read-out control means for controlling the read-out of data, a scaling factor generating means 10a for generating a scaling factor which is the reciprocal of the square root of the scaling factor given by the scaling factor setting means 9, an up counter 10b, A multiplier 10c for multiplying the scaling factor generated by the means 10a and the output of the up counter 10b,
The output of the maximum address value generating means 10d for generating the maximum address value of the line memory 5 and the output of the multiplier 10c are compared with the maximum address value generated by the maximum address value generating means 10d, and the output of the multiplier 10c determines the maximum address value. And a comparator 10e that generates a signal when the signal exceeds the threshold.
The scaling factor is (area of the scaled image) / (area of the original image), and the scaling factor is (length of the scaled image in the main (sub) scanning direction) / (main (sub) of the original image. ) Length in the scanning direction).

Here, the first switching means 4 connects the A / D converter 3 and the line memory 5 when the original image data output from the A / D converter 3 is written to the line memory 5, and connects with the line memory 5 when reading the original image data. The device 6 is connected. The second switching means 7 works in conjunction with the first switching means 4 to connect the line memory 5 and the writing control means 8 when writing the original image data to the line memory 5 and to connect the line memory 5 and the reading control means 10 when reading the original image data. Connect. Reference numeral 11 denotes a sub-scanning drive control unit that controls the driving of the sub-scanning driving unit 3 in accordance with the scaling ratio generated by the scaling ratio setting unit 9, and 12 denotes a sub-scanning drive that relatively moves the original 1 and the optical system unit 2. Means for generating a signal having a reference frequency corresponding to the scaling factor generated by the scaling factor generating means 10a, and a sub-scanning driving means 1 based on an output signal of the reference frequency generating means 11a.
And a PLL control means 11b for performing PLL control on the PLL 2.
101 is original image data, and 102 is scaled image data.

FIG. 2 is a timing chart for explaining the operation of this embodiment. 2A shows a write address given to the line memory from the write control means, and FIG.
Is the original image data to be written to the line memory, (c) is the switching signal output from the write control means, (d) is the scaled image data read from the line memory, (e)
Is a read address given to the line memory from the read control means, and (f) is a switching signal output from the read control means. In FIG. 2, h of 000h indicates a hexadecimal number, and X ₁ , X ₂ ,..., X ₁₇₂₈ indicate data of the first pixel, data of the second pixel,. .

FIG. 3 is a diagram showing the internal state of the line memory for explaining the zooming operation in this embodiment in detail.

The operation of the thus configured document reading apparatus of the present embodiment will be described below with reference to FIGS. 1, 2, and 3. FIG. It is assumed that the document reading apparatus according to the present embodiment reads a document of A4 size and a resolution of 8 dots / mm with the short side direction of the document as a main scanning direction, and sets a magnification of 16% for the entire area of A4.

The original 1 is irradiated on the light source 2a, and the reflected light is imaged on the photoelectric conversion element 2c by the lens 2b, and the optical signal is converted into an electric signal. The output of the photoelectric conversion element 2c is A / D converted by the A / D converter 3 to obtain original image data. At this time, the first switching means 4 connects the A / D converter 3 and the line memory 5, and the second switching means 7 connects the line memory 5 and the writing control means 8. The write control means 8 stores the second
As shown in FIG. 3A, the write addresses are sequentially given, and the data shown in FIG. 3B is converted into the first pixel data at address 000h, the second pixel data at address 001h, as shown in FIG.
... The 1728th pixel data is stored at address 6BFh, and one line of original image data is stored. When the original image data for one line is stored in the line memory 5, a switching signal is generated from the writing control means 8 as shown in FIG. 2 (c), and the first switching means 4 makes the output device 6 and the line memory 5
The second switching means 7 is switched to connect the line memory 5 and the reading control means 10. Thereafter, a scaling factor of 16% preset in the scaling factor setting means 9 is given to the scaling factor generating means 10a, and the scaling factor which is the reciprocal of the square root of this value = 1 / 0.16 ^{1 / 2} = 2.5
Is output. .. 000h, 001h, 002h,...
As shown in FIG. 2 (d), it is multiplied by c and stored in the line memory 5 as the read addresses 000h, 002h, 005h.
Addresses,..., 6BEh are given, and the scaled image data 102 as shown in FIG. 2 (e) from the line memory 5 is the first pixel data, the third pixel data, the sixth pixel data,.
Data is read out in the order of the 1727th pixel and supplied to the output device 6 at the next stage. This read operation is repeated to obtain one line of scaled image data. Before performing this read operation, the output of the multiplier 10c is always compared with the maximum address value (6BFh) of the maximum address value generation means 10d by the comparator 10e. When the output of the switch 10c exceeds the maximum address value, it is determined that the scaling of one line has been completed, and a switching signal as shown in FIG. 2 (f) is generated to generate the first switching means 4 and the second switching means.
Switching means 7 for switching the A / D converter 3, the line memory 5, and the line memory 5 and the writing control means 8, respectively.
And the above operation is repeated. In this way, one line of scaled image data is obtained.

Next, in the magnification change in the sub-scanning direction, the reference frequency generation means 11a receives a magnification coefficient (2.5) from the magnification coefficient generation means 10a, generates a reference signal having a frequency 2.5 times the frequency generated at the same magnification, and generates a PLL. This is given to the control means 11b. The PLL control means 11b performs PLL control of the sub-scanning drive means 12 by this reference signal, and keeps the speed at 2.5 times the speed at the same magnification. The sub-scanning drive unit 12 moves the optical system unit 2 in the direction of arrow A at a speed of 2.5 at the same magnification to perform zooming in the sub-scanning direction.

In this manner, the image is scaled at a magnification of 40% in both the main scanning direction and the sub-scanning direction, and an image having an area ratio of 16% with respect to the original image is obtained.

The case of reduction / magnification has been described above, but the magnification / magnification is also scaled similarly. Assuming that the scaling factor is 256%, the scaling factor 256% set in the scaling factor setting means 9 is given to the scaling factor generating means 10a, and the scaling factor = the reciprocal of the parallel root of this value from the scaling factor generating means 10a = 1 / 2.56 ^1/2 = 0.625 is output. .. 000h, 001h, 002h..., Which are the address values from the up counter 10b, are multiplied by the multiplier 10c, and read into the line memory 5 at the address 000h, 000h.
., And 001h, 001h,... Are read from the line memory 5, and are given to the output device 6 at the next stage. The rest of the operation is the same.

Next, the same applies to zooming in the sub-scanning direction.
11a receives the scaling factor (0.626) from the scaling factor generating means 10a, generates a reference signal having a frequency 0.625 times the frequency generated at the same magnification, and provides the reference signal to the PLL control means 11b. PLL control means 1
1b performs PLL control of the sub-scanning driving means 12 by this reference signal, and keeps the speed at 0.625 times the speed at the time of equal magnification. The sub-scanning drive unit 12 moves the optical system unit 2 in the direction of arrow A at a speed of 0.625 times the original magnification to perform magnification in the sub-scanning direction.

In this embodiment, the case where the number of line memories is one has been described, but the same applies to the case where there are two or more line memories. Especially two line memories
If more than one memory cell is used, one of the above operations is used for the write operation, and the other line memory is used for the read operation so that switching can be performed line by line, so that scaling can be performed faster than in this embodiment. Can be.

In this embodiment, the original reading apparatus is configured to perform scaling on the entire area of the A4 size.However, in order to correspond to an arbitrary original size or a partial area, the original reading or the original size may be detected by any method. Specify a partial area. That is, the magnification area is detected or specified. In the main scanning direction, the number of data of the scaled image data output in one line is calculated from the magnification and the scale area set in advance, and the number of data of the scaled image data output from the line memory is calculated. When the calculated number of data has been output, the next line is resized, and the sub-scanning direction is calculated from the pre-set magnification and re-magnification area by the sub-scanning drive speed and the feed length. Alternatively, the reading operation may be terminated when the data is sent by the calculated length at the calculated speed, so that useless read areas and read data are not output.

Further, in the present embodiment, when scaling in the main scanning direction, pixels are thinned out according to the scaling ratio, or the scaled image may be deteriorated when the scaling ratio is large and small due to overprinting, On the other hand, the following interpolation processing may be performed.

FIG. 4 is a diagram for explaining pixel interpolation processing in the main scanning direction. In FIG. 4, (a) shows the positional relationship between the read pixel and the pixel after interpolation, and X ₁ , X ₂ ,...
・ ・Y _1, Y _2, ··· is X _1, X _2, a pixel obtained by interpolation from .... (B) shows the relationship between the read pixel and the density of the pixel after interpolation.

An interpolation process for forming four pixels from two adjacent pixels by the internal division method will be described below with reference to FIG.

X _1, X ₂ from the photoelectric conversion element in the main scanning direction, ... are read, the multi-level data corresponding to the density of each pixel is A / D converted is obtained.

Now the density of X ₁ DX _1, pixel density of X ₂ obtained by interpolation between the _{D X2 Y 1, Y 2,} Y 3, the concentration of Y ₄ is a D _X1 at each point D _X2
Are represented by the intersection with the line connecting the
_Assuming that D _Y1 , D _Y2 , D _Y3 , and D _Y4 , these concentrations are D _Y1 = D _X1 , D _Y2 = 3/4 · D _X1 + 1/4 · D _X2 , D _Y3 = 2/4 · D _X1 + 2/4 · D _X2 , D _Y4 = 1/4 · D _X1 + 3/4 · D _X2 .

As described above, four pixels can be formed by interpolation from two adjacent pixels. This is repeated to obtain one line of interpolation data.

Assuming that the above operation is employed in this embodiment, first, a plurality of line memories are provided. The original image data for one line is stored in one of the line memories. Then, the original image data is read out, and the interpolation data is stored in another line memory while performing the above-described interpolation processing. The above operation is performed by the writing control means. Next, in this example, since the data is four times as large as the original image, the up counter 10b counts up in quadruple steps at the time of reading, and the address value given to the multiplier 10c is 000h, 004h, 008h.・ ・
The maximum address value generated by the maximum address value generation means 10d may be quadrupled.

By performing such interpolation processing, a smooth scaled image can be obtained even when the magnification is large or small.

In this example, four pixels are created from two pixels by interpolation, but various types of processing such as creating three pixels from two pixels can be considered.

Further, in this embodiment, the reference speed of the sub-scanning drive unit is set to the speed at the same magnification, but actually, the speed at the time of the minimum reduction / magnification is preferably set as the reference speed from the relationship between the speed and the torque.

As described above, in the present embodiment, the address is sequentially given to the line memory by the writing control means, the original image data for one line is temporarily stored, and then the read control means sets the original image data to the magnification set in advance in the magnification setting means. By giving a corresponding address to read out the scaled image data and performing scaling in the main scanning direction, and performing PLL control on the sub-scanning drive unit at a speed corresponding to the scaling ratio to perform scaling in the sub-scanning direction, it is simple. With the configuration, it is possible to obtain a scaled image of an arbitrary scale.

As described above, according to the present invention, according to the present invention, an address is sequentially given to the line memory by the write control means to temporarily store the original image data for one line, read the original image data from the line memory, and read the adjacent image data. Pixel data of three or more pixels is created from the two pixels by the internal division method, and this interpolated data is stored in another line memory. Thereafter, the read control means gives an address corresponding to the magnification set in advance to the magnification setting means, reads out the scaled image data, performs magnification in the main scanning direction, and sets the sub-scanning driving means to a speed corresponding to the magnification. By controlling the PLL to change the magnification in the sub-scanning direction, it is possible to obtain a magnified image with an arbitrary magnification with a simple configuration and obtain a smooth magnified image even when the magnification is large or small. The practical effect is great.

[Brief description of the drawings]

FIG. 1 is a block diagram of a document reading apparatus according to an embodiment of the present invention, FIG. 2 is a timing chart for explaining the operation of the apparatus, and FIG. FIG. 4 is a diagram illustrating an internal state, and FIG. 4 is a diagram illustrating an interpolation process in the main scanning direction. 1 original, 2 optical unit, 3 A / D converter, 4 first switching means, 5 line memory, 6
... output device, 7 ... second switching means, 8 ... write control means, 9 ... magnification setting means, 10 ... read control means, 11 ... sub-scanning drive control means, 12 ... sub-scanning Drive means.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-11570 (JP, A) JP-A-1-154670 (JP, A) JP-A-58-204666 (JP, A) (58) Investigation Field (Int.Cl. ⁶ , DB name) G06T 1/00 G06T 3/40 H04N 1/04

Claims (1)

(57) [Claims] A photoelectric conversion element for photoelectrically reading a document;
Sub-scanning driving means for relatively moving the photoelectric conversion element and the original, and A / D for A / D converting the output of the photoelectric conversion element
A converter, a plurality of line memories for storing one or more lines of original image data of the A / D converter, a scaling ratio setting means for setting an arbitrary scaling ratio, and one line of the plurality of line memories Operation of writing original image data to memory,
An operation of reading the original image data from the line memory in which the original image data is written, creating pixel data of three or more pixels from two adjacent pixels by the internal division method, and writing the interpolation data to another line memory. A document reading apparatus comprising: a writing control unit for controlling; and a sub-scanning drive control unit for controlling the sub-scanning drive unit in accordance with a scaling ratio set by the scaling ratio setting unit.