JPH0332949B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for reading and correcting image data using a line-type photo sensor, and in particular to a method for reading and correcting image data using a line-type photo sensor. The present invention relates to a method for correcting read image data that enables accurate reading.

(Prior Art) In recent years, with the increase in the density of line photo sensors (eg, CCD photo sensors), it has become possible to obtain highly accurate two-dimensional image data. The basic method is to image the light transmitted through the original 1 or the light reflected by the original 1 on the light receiving surface of the line type photo sensor 2 using the lens 3, as shown in FIG.
Furthermore, by sequentially changing the relative position of the line-type photo sensor and the document in the sub-scanning direction perpendicular to the longitudinal direction (main scanning direction) of the photo sensor, images of necessary portions of the document are sequentially scanned by the photo sensor. It performs photoelectric conversion.

Furthermore, to store a color image, R (red), G
It is necessary to obtain each image data of (green) and B (blue),
Conventionally, there have been several methods for obtaining the R, G, and B data, as described below.

One of them is R on the front of one photo sensor.
A filter corresponding to one of the colors G and B is installed, and all necessary parts of the document are scanned three times to obtain image data for each color, and the image data is temporarily stored in memory. After that, it is read out periodically.

Further, as shown in FIG. 5a, each of the R, G, and B separated color lights is obtained using dichroic filters 5, 5' or a half mirror and a color separation filter, and the light of each color is transmitted to the line photo sensors 2R, 2G,
There is also a method in which color signals of three colors are inputted to 2B and simultaneously obtained from each line sensor.

Still another method is to arrange three photo sensors 2R, 2G, and 2B in parallel on the same plane, and place a color separation filter corresponding to each color in front of each sensor, as shown in FIG. 5b. There is also a method in which separated color light obtained through a filter is made to enter each photo sensor.

Furthermore, the original is moved intermittently in a certain direction using a device as shown in FIG. Filters 5R, 5G corresponding to the three colors that are replaced in a time-divisional manner in the order of R, G, and B when the document 1 that moves intermittently is stationary;
There is also a method of arranging 5B (for example, Japanese Patent Laid-Open No. 56-58370).

In addition, a device as shown in FIG. 7 is used to move the document intermittently in a fixed direction, and light source lamps 6R, 6 corresponding to the three colors R, G, and B are arranged on the back side of the document.
There is also a method of blinking G and 6B in a time-divisional manner (for example, Japanese Patent Laid-Open No. 169472/1982 and Japanese Patent Laid-open No. 212255/1983).

A method in which data is collected in advance for one pixel of a CCD sensor and the data is corrected (e.g., patent application
35336) is also available. However, it does not respond to momentary changes in the amount of light.

(Problems to be Solved by the Invention) However, in any of the above methods, the amount of light emitted from the light source lamp may change over time due to factors such as changes in external voltage. Also R, G, B3
When using color filters or light source lamps, the effective amount of light emitted by each color before and after a certain period of time does not exactly match each other. Furthermore, in the above method of blinking the light source, even if the light emission time of one lamp is the same each time, the light emission intensity may not necessarily be the same due to various external and internal factors. Therefore, it is difficult to make the amount of light emission the same.

This invention has been proposed in view of the above-mentioned conventional problems, and its first purpose is to provide a method for blinking a light source that is accurate and does not depend on changes in the effective amount of light emitted each time the light source is turned on. The purpose of this invention is to provide a method that can obtain accurate image data. At the same time, it is an object of the present invention to provide a method capable of correcting fluctuations in the amount of light emitted over time and, when using document illumination light of a plurality of colors, the difference in the effective amount of light emitted between each color light.

(Means for solving the problem) The present invention employs the following means to achieve the above object. That is, the line-type photo sensor and the original are sub-scanned relatively and intermittently in the sub-scanning direction perpendicular to the main-scanning direction of the photo sensor, and while the sub-scanning is stopped, R (red), G
(Green) and B (Blue) light source lamps are sequentially blinked, and while each of these light source lamps is on, the line-type photo sensor receives colored light from the light source lamps obtained through the document. In addition to determining the effective amount of light received, the control photo sensor directly receives the colored light from the lit light source lamp to determine the amount of light emitted by the light source lamp itself, and the value is obtained by dividing the effective amount of light received by the amount of light emitted. is extracted as image data, and when the extraction of the image data while the light source lamps are sequentially blinking and each light source lamp is lit is completed for one main scanning line, the sub-scanning feed is changed to the sub-scanning width of one main scanning line. , and then moves on to extracting image data for the next main scanning line.

(Example) and (effect) A more detailed explanation will be given below based on the drawings.

FIG. 1 shows a block diagram of an example of an apparatus for carrying out the present invention, and FIGS. 2a and 2b show examples of timing charts thereof.

The document table 11 is moved in a fixed direction by a sub-scanning motor 12 which rotates intermittently in response to a sub-scanning drive signal P _n outputted from a sub-scanning control circuit 14 . Three light source lamps 6R, 6G, and 6B corresponding to each color of R, G, and B are arranged on the back side of the document table 11.
The document table 11 is kept stationary by light source drive signals Pl (P _lR , P _lG , P _lB ) corresponding to the respective lamps 6R, 6G, and 6B outputted from the light source control circuit 16. Flashes in sequence in between. When the light source lamp 6B finishes blinking, the motor 12 is rotated by the sub-scanning drive signal P _n to advance the document table in a fixed direction (sub-scanning direction) by the width of one main-scanning line. On the other hand, after the light of each color irradiated onto the original as described above passes through the original A, an image is formed on the light receiving surface of the CCD line photo sensor 2 via an optical device 80 such as a lens. Charge corresponding to the amount of transmitted light is accumulated in each element. The CCD line photo sensor 2 is driven by a CCD drive signal P _D output from a CCD drive circuit 17 as described below. That is, the time between each pulse of the drive signal P _D is defined as the charge accumulation time, and for example,
As shown in the figure, if a charge corresponding to the R signal is accumulated in a certain period T _R , then in the next period T _G , the light reception signal D _R accumulated in the above T _R period is output, and the charge corresponding to the G signal is accumulated. Then, in the next period T _B , the received light signal D _G accumulated in the above T _G period is
At the same time, the charge corresponding to the B signal is accumulated.

Based on the charges accumulated as above, R,
The received light signal D (D _R , D _G ,
D _B ) is time-divisionally input to the light amount correction divider 21 described below. A control photo sensor 8 is disposed in front of the light sources 6R, 6G, and 6B, and a signal from the control photo sensor 8 is input to a light amount monitor circuit 40 to directly control the light sources 6R, 6G, and 6B. The effective amount of light emitted is detected. It is desirable to use a control photo sensor 8 whose spectral sensitivity characteristics are as close as possible to those of a CCD line photo sensor.

That is, the light amount monitor circuit 40 is in principle the third
It is configured as shown in the figure, and the signal C from the control photo sensor 8 is temporarily stored in a capacitor 41, and the sampling signal is inputted from the timing signal generation circuit 15 via an analog switch 42.
The signal is input to the sampling holder 43 by _PS . The sampling holder 43 holds the input value until the next sampling signal P _S is input, and also uses that signal, that is, the correction signal C (C _R ,
C _G , C _B ) are input to a light amount correction divider 21, which will be described later, in synchronization with the input of the R, G, and B signals. The analog switch 42 is normally connected to the capacitor 41.
However, after the sampling signal P _S is output, it is temporarily grounded by the reset signal Pr output from the timing signal generation circuit 15 and remains in the capacitor 41. It is designed to discharge electric charge. The light amount correction divider 21 divides the R, G, and B signals input as described above by the respective correction signals C _R , C _G , and C _B and divides them into R, G, and B image data. It is input to the processing circuit 19. This preprocessing circuit 19 is equipped with an AD converter, and converts the input R, G, and B image data into an AD converter.
After conversion and further color correction and gradation correction as necessary, each color signal is temporarily stored in the buffer memories 20R, 20G, 20B via the selector 22, and then input to the image processing circuit 31. This circuit is basically controlled as described above. However, in such an apparatus, it is necessary to prevent the R, G, and B image data from being mixed with each other.
Therefore, in the control method shown in Figure 2a, the CCD
Each light source 6R, within each integration period T (T _R , T _G , T _B )
6G and 6B are turned on and off.
In addition, in the control method shown in FIG. 2b, a waste time E is provided before (after) the integration period for each color of R, G, and B, and each light source lamp 6R, 6G, and 6B is
The light is turned on at a discard time E before the integration period for each color, and is turned off at a discard time E after the integration period. Therefore, the image data D _E obtained during the discard time E contains two color signals, but this signal is not used.

Needless to say, the light amount correction divider 21 is controlled in consideration of the characteristics of the control photo sensor 8 so as to obtain a white balance of the RGB output signals.

(Effects) As explained above, in this invention, the value obtained by dividing the data obtained from the line photo sensor by the direct effective light emission amount of the light source is used as image data, so it is possible to avoid fluctuations in the effective light emission amount of the light source itself. This has the effect of allowing accurate image data to be obtained without being influenced by In particular, in the method of obtaining the R, G, and B color signals in a time-sharing manner by blinking the R, G, and B light sources, it is possible to compensate for changes in the light emission intensity of the light sources, which differ each time the light sources are turned on. can.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a device for carrying out the present invention, FIG. 2 is a timing chart of the device shown in FIG. 1, and FIG. 3 is a diagram showing in more detail the light amount motor used in the device shown in FIG. 4 is a principle diagram of obtaining two-dimensional image data using a line-type photo sensor, and FIG. 5 is a schematic diagram of an example of obtaining two-dimensional color image data using a line-type photo sensor. FIGS. 6 and 7 are schematic diagrams showing other examples of obtaining color image data. In the figure, 2... CCD line photo sensor, 6...
...Light source lamp, 8...Control photo sensor, 11
...Original table, 17...CCD drive circuit, 2
1... Light amount correction divider, 30... Lens, 40...
...Light level monitor circuit, A...Manuscript.

Claims (1)

[Scope of Claims] 1. A line type photo sensor and a document are sub-scanned relatively and intermittently in a sub-scanning direction perpendicular to the main-scanning direction of the photo sensor, and while the sub-scanning is stopped, R (red), G (green), B
(Blue) Each light source lamp is blinked in sequence, and while each of these light source lamps is on, the line-type photo sensor receives the colored light from the light source lamp obtained through the document to determine the effective amount of received light. At the same time, the control photo sensor directly receives the colored light from the lit light source lamp to determine the amount of light emitted from the light source lamp itself, and the value obtained by dividing the effective amount of light received by the amount of light emitted is extracted as image data. When the sequential blinking of each light source lamp and the extraction of the image data for one main scanning line are completed, the sub-scanning is performed by a sub-scanning width of one main scanning line, and the next An image reading correction method characterized by proceeding to extracting image data for main scanning lines.