JPH04318757A - Color picture reader - Google Patents

Abstract

PURPOSE:To read a picture at a faster speed by using one memory for storing a shading data. CONSTITUTION:Every time picture scanning is finished, to which of a 1st white color board 30 and a 2nd white color board 31 the position of a scanning unit 7 is closer is discriminated. After a motor 6 is driven to restore the scanning unit 7 to the position of any white color board discriminated closer, the sub scanning is started. Every time the scanning unit 7 is restored to the position of the 1st or the 2nd white color board, red, green, blue fluorescent lights 71, 72, 73 switchingly lighted according to a predetermined sequence.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen-sequential color image reading device that reads images one page at a time for each color to be read.

0002

2. Description of the Related Art There is a market demand for color scanners to read more accurate image data faster. In order to obtain highly accurate image data using a color scanner, it is necessary to correct the uneven illuminance of the light source.
Therefore, it is necessary to perform shading correction.

Next, conventional shading correction will be explained. When reading density information in a linear region using a CCD linear sensor or the like, even if the density is uniform, a signal at a constant level is not output due to uneven illuminance and optical characteristics of the light source. Shading correction is the process of correcting this signal to make it a value proportional to the reflectance of the original. In order to correct shading, it is sufficient to read a white plate whose density distribution is known in advance and examine the influence of the reading system on the output signal of the sensor.

Next, a specific example of this method will be described. first,
A white plate with a known density distribution is placed in a readable area close to the outside of the document placement range, and one line of the white plate is stored as shading data in a memory within the apparatus. Then, the read image signal is corrected based on the shading data stored when reading the original.

In the case of a color scanner that sequentially reads images one page at a time for each color to be read, the above operation is performed for each color since the shading waveform generally differs for each color to be read. In other words, the image was read in one color, and each time the image was read, the reading unit was moved to the reading position on the white board and the shading data was read again.

[0006] In this type of color scanner, a method of reading at a higher speed is to read shading data for two colors in advance into a memory for two or more lines, and then turn the scanner on after the scanning unit has read one screen. When returning, a method of performing a reading operation using another reading color may be considered.

[0007]

However, this method has a problem in that an additional memory is required to store the shading data.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a color image reading device that uses one memory for storing shading data and can read images at higher speed.

[0009]

[Means for Solving the Problems] In order to achieve such an object, the present invention provides first and second white plates provided at the ends of the image reading area in the sub-scanning direction, and an image scanning area. determining means for determining whether the position of the sub-scanning means is closer to the first or second white plate each time the sub-scanning unit is finished; a drive control means for starting sub-scanning after the return;
The drive control means causes the sub-scanning means to scan the first or second scanning means.
The light source switching means switches and lights up the light sources in accordance with a predetermined order each time the light source is returned to the position of the white plate.

0010

[Operation] In the present invention, when the sub-scanning means is located at the edge of the image, the determining means determines whether the position of the sub-scanning means is closer to the first or second white plate; After the sub-scanning means is returned to the position of the white plate determined to be close by the drive control means, sub-scanning is started, and the sub-scanning means is returned to the position of the first or second white plate by the drive control means. Each time, the light sources are switched on and turned on according to a predetermined order by the light source switching means.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. This is 3
An example of a color scanner that illuminates and reads a document with a colored light source is shown in FIG. 2, and its structure is shown in FIG.

In FIG. 2, a document 2 is placed on top of a glass 4 supported by a window at the top of the main body of the apparatus. 1
is a pressure plate that presses down the original 2. A first white plate 30 is attached to the right end of the upper surface of the glass 4 in FIG. 2, and is uniformly white over the entire area in the main scanning direction. A second white plate 31 is attached to the left end of the upper surface of the glass 4 in FIG. 2, and is uniformly white over the entire area in the main scanning direction. A scanning unit 7 is disposed so as to be movable in parallel in the sub-scanning direction, and is driven by a stepping motor 6 via a belt 5. 8 is C
It is a PU board and processes image signals sent from the CCD 78. Image data is being transmitted through interface connector 9.

FIG. 3 shows the configuration of the scanning unit 7 shown in FIG. 2.

In FIG. 3, 71 is a red fluorescent lamp, 72 is a green fluorescent lamp, and 73 is a blue fluorescent lamp, which illuminate the original 2. Reference numeral 79 denotes an inverter unit that lights the red, green, and blue fluorescent lamps 71, 72, and 73 at high frequency. The reflected light from the original 2 is reflected by mirrors 74, 75, and 76 in this order, and is sent to a CCD sensor 78 by a lens 77.
imaged on the light-receiving surface. In the CCD sensor 78, photoelectric conversion elements are arranged in a straight line, and the charge of each photoelectric conversion element is sequentially shifted and output.

FIG. 1 shows the configuration of the CPU board 8 shown in FIG. 2. As shown in FIG.

In FIG. 1, 6, 71, 72, 73, 7
9 indicates the same part as FIG. 3. 81 is a ROM in which a control program is stored. 82 is a RAM in which shading data is stored. 83 is CPU, RO
The motor driver 84, inverter unit 79, etc. are controlled according to the program stored in M81. 84 is a motor driver, which drives the stepping motor 6.
It is what drives the.

Reference numeral 91 denotes a host computer which receives reading commands and reading windows (x0, y0) to (x1, y1).
) is sent to the CPU 83. FIG. 5 is a flowchart showing a control program stored in the ROM 81 shown in FIG.

The color scanner is also in a reset state when the power is turned on, and when the color scanner is reset, the control program stored in the ROM 81 is executed.

[0020] In step S1, the scanning unit 7 is
The white board 30 is moved to the position of the white board 30, the red fluorescent lamp 71 is turned on, the white area of the white board 30 is read, and the read shading data is stored in the RAM 82.

Next, in step S2, a read command from the host computer 91 and a read window (x
0, y0) to (x1, y1), and upon receiving the read command and parameters, step S
3, and in step S3, the scanning unit 7 is
to start reading the designated reading window.

When the reading by the red fluorescent lamp 71 is completed, in step S4, the red, green, and blue fluorescent lamps 7 are turned on.
It is determined whether reading by 1, 72, and 73 is completed. In this case, since reading by the red fluorescent lamp 71 has been completed, the process moves to step S5. In step S5, the reading color is changed to green fluorescent lamp 72, and in step S6,
Based on the reading windows (x0, y0) to (x1, y1), it is determined whether the position of y1 is closer to the first white plate 30 or the second white plate 31.

In this case, since it is closer to the second white plate 31, the scanning unit 7 is moved in the direction of arrow A shown in FIG. 72 is turned on, the white area of the second white plate 31 is read, and the read shading data is stored in the RAM 82.
to be memorized. Next, the scanning unit 7 is moved in the direction of arrow B shown in FIG. 4, and in step S3, reading of the specified reading window is started.

When the reading is completed, it is determined in step S4 whether reading by the red, green, and blue fluorescent lights 71, 72, and 73 has been completed. In this case, since the reading using the two red and green fluorescent lights 71 and 72 has been completed, the process moves to step S5. In step S5, the reading color is changed to the blue fluorescent lamp 73, and in step S6, based on the reading windows (x0, y0) to (x1, y1), the position of y0 is changed to the first white plate 30 or the second white plate 30. It is determined which of the white plates 31 it is closer to.

In this case, since it is closer to the first white plate 30, the scanning unit 7 is moved in the direction of arrow B shown in FIG. 73 is turned on, the white area of the first white plate 30 is read, and the read shading data is stored in the RAM 82.
to be memorized. Next, in step S3, the scanning unit 7 is moved in the direction of arrow A shown in FIG. 4 to start reading the designated reading window.

When the reading is completed, it is determined in step S4 whether reading using the three red, green, and blue fluorescent lights 71, 72, and 73 has been completed. In this case, reading by the red, green, and blue fluorescent lights 71, 72, and 73 has been completed, so all reading operations are completed and step S
Return to 1.

[0027]

[Effects of the Invention] As explained above, according to the present invention,
With the above configuration, there is an effect that images can be read at higher speed using one memory for storing shading data.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the structure of an image reading device according to an embodiment.

FIG. 3 is a diagram showing the configuration of the scanning unit 7 shown in FIG. 2;

FIG. 4 is a diagram showing an example of coordinates of a reading area.

FIG. 5 is a flowchart showing a control program stored in the ROM 81 shown in FIG. 1;

[Explanation of symbols]

6 Stepping motor 7 Scanning unit 71 Red fluorescent light 72 Green fluorescent light 73 Blue fluorescent light 79 Inverter unit 81 ROM 82 RAM 83 CPU 84 Motor driver

Claims (1)

[Claims] 1. First and second white plates respectively provided at ends in the sub-scanning direction of an image reading area; and each time image scanning is completed, the position of the sub-scanning means is changed to the first or second white plate. determining means for determining which of the white plates is closer to the white plate; drive control means for starting sub-scanning after returning the sub-scanning means to the position of the white plate determined to be closer to the white plate; A color image reading device comprising: a light source switching means for switching and lighting the light sources in accordance with a predetermined order each time the sub-scanning means is returned to the position of the first or second white plate.