JPH057276A - Color image reader - Google Patents

Abstract

PURPOSE:To improve color separation capability without degrading the S/N of an image signal. CONSTITUTION:Only one single color light source out of three single color light sources 111,112 and 113 is turned on during the storage period of a CCD104 corresponding to the single light source and the lighted single color light source is turned off during the storage period corresponding to the data reading period of the single color light source. This cycle is repeated by a light source lighting circuit 110 while changing the light source to be lighted in order and the CCD104 is driven by a CCD driving circuit 107 during a storage period corresponding to the data read-out period to read out the data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image reading apparatus in which three monochromatic light sources are sequentially turned on and an original image is read by an image reading element.

[0002]

2. Description of the Related Art Conventionally, in a color image reading apparatus in which three monochromatic light sources are sequentially turned on and an original image is read by a line image sensor, as shown in FIG. A color image was read by turning on and off one of the three monochromatic light sources.

[0003]

However, in the above-mentioned conventional example, since one light source is turned on and off within one storage section, the light source lighting circuit is provided to set the on time and off time of the light source. There is a problem in that it becomes complicated, and the color of each light source is mixed due to the afterglow characteristics of the light source, resulting in poor color reproducibility.

In order to prevent color mixture, the light source must be turned off for a long time as shown in FIG. 4, resulting in a long storage time and S / N of the image signal. There was a problem that the ratio fell.

An object of the present invention is to solve the above problems and to provide a color image reading apparatus having excellent color separation performance without lowering the S / N ratio of the image signal.

[0006]

In order to achieve such an object, the present invention provides a color image reading apparatus in which three monochromatic light sources are sequentially turned on to read an image by an image reading element. Only one single light source of the single color light sources is turned on during the storage section of the image reading element corresponding to the single light source, and the turned on single color light source is stored in the storage section corresponding to the data reading period of the single color light source. It is characterized by comprising a control means for repeating the cycle of turning off the light source while sequentially changing the turned-on monochromatic light source, and a reading means for reading out data in an accumulation section corresponding to the data reading period.

[0007]

In the present invention, only one of the three monochromatic light sources is turned on during the accumulation section of the image reading element corresponding to the monochromatic light source, and the illuminated monochromatic light source is used as the data of the monochromatic light source. The control unit repeats the cycle of turning off the light during the accumulation period corresponding to the reading period by sequentially changing the illuminated monochromatic light source, and the reading unit reads the data during the accumulation period corresponding to the data reading period.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

The CPU 109 causes the CCD drive circuit 107 to C
The storage time for driving the CD 104 is set. The CCD drive circuit 107 takes in this set value at / SP, sets the length of the next accumulation section, and drives the CCD 104.

The CPU 109 causes the light source lighting circuit 110 to have red (R), green (G), and blue (B) light sources 111, 112, 1
13 is turned on and off, and the light source lighting circuit 110 turns on and off the light source in synchronization with / SP based on this instruction.
F The light emitted from the light sources 111, 112, 113 is the original 1
The light is reflected by 01, is subjected to shading correction by the shading correction plate 102, and is imaged on the CCD 104 by the lens 103.

The signal output of the CCD 104 is amplified by an amplifier 105 and converted into a digital signal by an A / D converter 106.

Reference numeral 108 is a D flip-flop for generating a valid data signal for distinguishing the valid image signal from the invalid image signal, which is initialized by the CPU 109 so that the valid data signal has the timing shown in FIG.

FIG. 2 is a timing chart showing the ON / OFF timing of the light source of this embodiment.

/ SP is a signal indicating the accumulation section, and / S
One accumulation section is from the fall of P to the next fall.

The signal RON for lighting the red (R) light source is turned on from OFF in synchronization with / SP, and the green (G) light source lighting signal GON and the blue (B) light source lighting signal BON are kept off. Then, the light amount of R gradually increases due to the rising characteristic of the light source and reaches the steady light amount. R image information is accumulated in this accumulation section. In the next accumulation section,
RON is turned off from ON, GON and BON are kept OFF. In this accumulation section, the amount of R light gradually decreases due to the falling characteristic of the light source. GON is switched from OFF to ON in synchronization with the next / SP, and RON and GON are OF
Leave as F. In this way, only RON in the accumulation section is O
N, RON, GON, and BON are all OF in the accumulation section
F, only GON is ON in the accumulation section, RO is in the accumulation section
N, GON, BON are all OFF, BON in the accumulation section
Only ON, and RON, GON, and BON are all OFF in the accumulation section. By controlling the light source lighting circuit in the above sequence, the image information accumulated in the accumulation section is R
This image information of R is CC information during the accumulation section.
It is output from D.

Similarly, G image information is accumulated in the accumulation section and is output from the CCD in the accumulation section. The image information of B is accumulated in the accumulation section and is output from the CCD in the accumulation section. The image data output to these storage sections is identified by the valid data signal and input to the processing circuit in the subsequent stage. In the subsequent processing circuit, only image data whose valid data signal is true is identified, selected, and processed.

[0018]

As described above, according to the present invention,
With the configuration as described above, it is possible to realize an image reading apparatus excellent in color separation performance without lowering the S / N ratio of the image signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing a reading unit of an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart showing an example of the timing of this embodiment.

FIG. 3 is a timing chart showing an example of timing of a conventional image reading apparatus.

FIG. 4 is a timing chart showing another example of the timing of the conventional image reading apparatus.

[Explanation of symbols]

 101 Original Document 102 Shading Correction Plate 103 Lens 104 CCD Sensor 105 Amplifier 106 A / D Converter 107 CCD Driving Circuit 108 D Flip-Flop 109 CPU 110 Light Source Lighting Circuit 111 Light Source (Red) 112 Light Source (Green) 113 Light Source (Blue)

Claims (1)

Claim: What is claimed is: 1. A color image reading apparatus for reading an image by an image reading device by sequentially lighting three monochromatic light sources intermittently, wherein only one of the three monochromatic light sources is used. A single color is turned on during a storage section of the image reading element corresponding to the single light source, and a cycle of turning off the turned-on single color light source during a storage section corresponding to a data reading period of the single color light source. A color image reading apparatus comprising: a control unit that sequentially changes the light source and repeats the reading unit; and a reading unit that reads out data in an accumulation section corresponding to the data reading period.