JPS63286058A - Color picture reader - Google Patents

Abstract

PURPOSE:To output excellent picture information with simple constitution by generating a timing signal changing at least the storage time of an image sensor into two kinds or over in time series. CONSTITUTION:SH is a signal to complete (start) one storage time of an image sensor 5 and the output of the image sensor 5 with respect to a prescribed luminous quantity depends on the interval (t) of the SH. A timing generating section 6 sets the interval of the timing SH of image sensor drive, that is, tr, tg, tb so as to be arranged. Thus, the storage time of the image sensor 5 is changed in each color and the outputs of the image sensor of each color are arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a color image reading device for color-separating a color document line by line in time series and reading image information thereof.

(Prior Art) First, a general light source sequential type color image reading device will be described.

Fig. 1 is a schematic diagram of the reading unit, Fig. 2 is an overall control block diagram, Fig. 3 is a drive timing chart of the image sensor, Fig. 4 is a timing chart showing the sensor output level according to the present invention, and Fig. 5 is a similar timing chart according to a conventional example, and FIG. 6 is a spectral characteristic diagram.

In FIG. 1, a document 0 is illuminated by a light source 2, and the reflected light passes through a mirror 3 and a lens 4 to an image sensor 5.
is imaged. Light source 2 is red 2r.

It is composed of fluorescent lights of three colors, green 2g and blue 2b, and only one color of each color is lit during one accumulation time of the image sensor 5.
One line of three-color image information is obtained in the accumulation time. By repeating this process, all image information can be obtained. The blinking of the light source and the driving of the image sensor are generally performed by a timing generator 6 shown in FIG.

On the other hand, the output of the image sensor 5 passes through the amplifier 8,
After being digitally converted by the D converter 9 and subjected to various signal processing such as shading correction, T correction, and MTF correction by the signal correction section 10, it is outputted to the outside through the interface 11. Here, various signal processing may be performed before digital conversion.

Since the above processing is not important in the present invention, it will not be discussed here.

The timing generating section 6 generates various timings for driving the main body and signal processing, but here, we will focus on the timing for driving the image sensor and explain it with reference to FIG.

-i, the image reading device reads the 1' line and the LS
Many of them output YNC (horizontal synchronization signal).

Here, SH is a signal that ends (starts) one accumulation time of the image sensor 5, and the output of the image sensor 5 for a constant amount of light is determined by the interval t of this SH. 01.02 is a signal that takes out the signals transferred to the shift register one by one from the beginning to the output line, and the number of 01 and 02 in the SH interval is determined by the number of pixels of the image sensor. I'm judging.

Generally, the overall sensitivity characteristics for each color (r) are determined by the spectral characteristics of the light source, optical system, and image sensor, as shown in Figure 6.

g and b) are different. In other words, even if you read a document that shows uniform reflection in the visible light wavelength range, the output level of each color will differ if the storage time of the image sensor 5 is constant (as is clear in Figure 5). , output levels V'r, V'g.

There is a difference in v’b).

This means that when A/D converting a signal with a lower output than other color signals, it is amplified to almost the same level as the output of the other color signals, or by changing the reference voltage of the A/D converter. This is corrected by aligning the output levels. However, in order to amplify the noise level at this time, the output signal S
/N is supposed to be bad.

In order to solve this problem, it may be possible to increase the output level by increasing the light output of the light source, but in this case, the life of the lamp may be shortened, or when using a white light source to perform spectroscopy using a filter, the output of a color signal with high sensitivity may be considered. There is a risk of saturation.

(Purpose) The present invention has been accomplished based on this background,
It is an object of the present invention to provide a color image reading device that eliminates the drawbacks of the conventional example and outputs good image information with a simple configuration.

(Structure) For this purpose, the present invention includes a timing generation section that generates a first timing signal SH that changes the accumulation time of the image sensor in at least two types in time series, and further includes a timing generation section that generates a first timing signal SH that changes the accumulation time of the image sensor in at least two types in time series. The present invention is characterized by having a timing generating section that generates second timing signals at equal intervals indicating the start or end of reading one line of image information according to one set.

FIGS. 7 and 8 are circuit diagram examples for creating LSYNC, SH, and 01 during the timing shown in FIG. 3, relating to one embodiment.

FIG. 7 is a circuit diagram up to outputting LSYNC and SH, and FIG. 8 is a circuit diagram up to outputting 01.

If the accumulation time of the image sensor 5 is changed for each color, the outputs of the image sensors of each color can be made uniform, but in order to do so, the intervals of SH in FIG. 3, that is, tr, tg, tb
You can set them arbitrarily (so that they match).

In this embodiment, this is done by the ditub switches 12 and 13.

Further, 01 is designed so that a predetermined number of clocks are output (1024 in FIG. 8) after the SH multiplied signal is input.

Further, the SH interval is longer than the shortest output period tQ (by setting the counter CNT in the circuit).

By having an external or internal signal processing circuit recognize the image data output for each LSYNC as one line, it can be used for various signal corrections and I/F timings.

(Effects) The present invention is as described above, and according to the present invention, a color image reading device is provided that can obtain stable image sensor output with timing that can be made with a simple circuit and outputs good image information. I can do it.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the reading unit, Fig. 2 is an overall control block diagram, Fig. 3 is a drive timing chart of the image sensor, Fig. 4 is a timing chart showing the sensor output level according to the present invention, and Fig. 5 6 is a similar timing chart according to a conventional example, FIG. 6 is a spectral characteristic diagram, and FIGS. 7 and 8 are storage time setting circuit diagrams of an image sensor according to an embodiment of the present invention. 12.13...Dip switch for timing setting. Figure 1 Figure 2 Cause Figure 3 Figure 4 Figure 5 WA H s6 Figure 8

Claims (5)

[Claims] (1) A light source that illuminates the original, an imaging optical system that forms an image of the light reflected from the original, a color separation means that separates the colors between the light source and the imaging unit, and a color separation unit that separates the colors of the imaged original. In a color image reading device that has an image sensor that reads a color document, separates the colors of a color document line by line in time series, and reads the image information, the storage time of the image sensor is changed over time in at least two or more types. It has a timing generating section that generates a first timing signal SH, and further includes a timing generator that generates a first timing signal SH at equal intervals, which indicates the start or end of reading one line of image information, according to one set of SH interval types. A color image reading device characterized by having a timing generation section that generates a timing signal. (2) The color image reading device according to claim (1), wherein color separation is performed by blinking light sources of a plurality of colors. (3) Color separation timing is determined by the first timing signal SH
The color image reading device according to claim 1, wherein the color image reading device changes to the next color component depending on the color component. (4) The color image reading device according to claim (1), further comprising a timing generator capable of arbitrarily adjusting a ratio of different intervals of the first timing signal SH. (5) The color image reading device according to claim (4), wherein a limit value of the SH interval is set to be longer than the time required to transfer all pixel data of the image sensor.