JPH06113073A - Color picture reader - Google Patents

Abstract

PURPOSE:To simplify circuit configuration and to improve cost effectiveness by systematizing a circuit part for processing sensor output in one in a device for reading pictures using a point sequential system. CONSTITUTION:A document is read by receiving reflected light from a document surface by a photoelectric conversion circuit 12 provided with three sensors for R, G and B and the signals of R, G and B for one picture element unit from the respective sensors are time divided in one picture element by an analog switch 13 and outputted. Then, by passing the time divided signals through a gain correction part 15, a distortion correction part 16 and an A/D conversion part 18, they are fetched as digital data. Thus, the circuit part of the sensor output is systematized in one.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an image scanner,
The present invention relates to a color image reading device applied to a facsimile device, a digital copying machine and the like.

[0002]

2. Description of the Related Art Three types of image reading methods for color image reading apparatuses are known: an area sequential method, a line sequential method, and a dot sequential method.

The frame-sequential method uses a single sensor as shown in FIG.
As shown in (a) of the above, it is a method of reading the three primary colors of red, green, and blue (hereinafter referred to as R, G, B) page by page.
The line-sequential method uses one line-shaped sensor as shown in FIG.
As shown in (b), it is a system that reads the three primary colors of R, G, and B line by line. The dot-sequential system uses three sensors, and as shown in (c) of FIG. , B of the three primary colors are simultaneously read in pixel units.

As a color image reading apparatus using the dot-sequential system, the one shown in FIG. 5 is conventionally known.

This is because the light from the light source 1 is reflected on the surface of the original, and the reflected light is received by a photoelectric conversion circuit 2 having three sensors for R, G, and B to read the original, and each is read. The signal from the sensor is fed to the gain correction section 3a,
It is supplied to 3b and 3c. Each sensor of the photoelectric conversion circuit 2 is driven by the sensor drive circuit 4 at a predetermined timing.

Each of the gain correction sections 3a, 3b and 3c performs gain correction for equalizing the level difference between the input signals and then supplies them to the distortion correction sections 5a, 5b and 5c, respectively. In each of the distortion correction units 5a, 5b and 5c, the correction of the distortion of the sensor output due to the uneven light amount of the light source 1 and the dark output of the sensor is performed by the RAM (random access memory) 6a, 6a.
The corrected data is supplied to the A / D converters 7a, 7b and 7c, respectively. The A / D converters 7a, 7b, 7c are adapted to digitally convert the input analog signals and output them to the outside.

[0007]

As described above, the conventional color image reading apparatus using the dot-sequential system is the photoelectric conversion circuit 2
A gain correction unit for processing the signal from each sensor of
It is necessary to incorporate three systems of circuits including a distortion correction unit and an A / D conversion unit, which complicates the circuit configuration and increases the number of circuit components to be used, resulting in poor economy.

In view of the above, the present invention intends to provide a color image reading apparatus which uses a dot-sequential system and which has a single circuit section for processing sensor output, which can simplify the circuit configuration and improve the economical efficiency. To do.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a photoelectric conversion circuit for simultaneously reading three primary colors of red, green, and blue from an original by a dot-sequential method using a sensor, and each color signal from the photoelectric conversion circuit are combined into one. It comprises a time-division control unit for time-divisionally outputting each pixel and an A / D conversion unit for digitally converting and outputting the color signal from this control unit.

[0010]

In the present invention having such a configuration, each color signal from the photoelectric conversion circuit is time-divided and output for each pixel by the time division control means, and the time-divided color signal is shared by the common A
The digital signal is converted into a digital signal by the / D converter and output.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the light from the light source 11 is reflected on the surface of the original, and the reflected light is received by a photoelectric conversion circuit 12 having three R, G, and B sensors, so that the original is scanned. Reading is performed and the analog electric signal of each pixel from each sensor is simultaneously supplied to the analog switch 13 which is a time division control means. The photoelectric conversion circuit 12 is provided with a filter or the like for color-separating the input light, and the light is input to each sensor via this filter.

The analog switch 13 is adapted to sequentially select and output the signals from the respective sensors within one pixel.

The operation timing of the photoelectric conversion circuit 12 and the analog switch 13 is determined by a sensor drive circuit 14. Then, the analog switch 13 determines which signal is output by the sensor drive circuit 14, and the output signal from the analog switch 13 is a signal in which the R, G, B signals are time-divided in the output time for one pixel. ing.

The signal output from the analog switch 13 is supplied to the gain correction section 15. The gain correction unit 15 corrects and equalizes the level difference between the input R, G, and B signals, and the corrected signal is corrected by the distortion correction unit 16
Is being supplied to.

The distortion correcting section 16 corrects the distortion of the sensor output due to the uneven light quantity of the light source 11 and the dark output of the sensor using the correction data from the RAM (random access memory) 17 for distortion correction. The corrected signal is supplied to the A / D conversion unit 18. The A / D converter 1
Reference numeral 8 is adapted to convert an inputted analog signal into a digital signal and output it to the outside.

In the embodiment having such a structure, the R, G, B signals from the photoelectric conversion circuit 12 after the document surface is read by the respective sensors are shown in FIG. The signal becomes as shown in FIG.
The signal is as shown in (a). Here, the amplitudes of the R, G, and B signals differ because of the spectral characteristics of the light source 11 and the sensitivity of the sensor.

The R, G and B signals from the photoelectric conversion circuit 12 are supplied to the analog switch 13. The analog switch 13 is supplied with select signals RSe, GSe and BSe as shown in FIG. 3A from the sensor drive circuit 14 within the output time for one pixel.

As a result, the analog switch 13 outputs a time-divided signal within one pixel as shown in FIG. It should be noted that the overall view of this signal is as shown in FIG.

In the gain correction section 15, R, G,
The level difference between the B signals is corrected and equalized. In this way, the signal of one pixel as shown in FIG. 3 (c) is obtained.
If this signal is viewed as a whole, it becomes a signal as shown in FIG.

The signal after this correction is subsequently sent to the distortion correction unit 16
Is supplied to. The distortion correction unit 16 corrects the distortion of the input signal with the correction data from the distortion correction RAM 17. Thus, the signal output from the distortion correction unit 16 becomes a signal as shown in (d) of FIG. 2, and the A / D conversion unit 18
Is supplied to. In the A / D converter 18, the input analog signal is digitally converted and output as digital data to the outside.

As described above, the R, G, and B signals output from the respective sensors of the photoelectric conversion circuit 12 are sent to the analog switch 1.
3 converts the signals into time-divided signals in one pixel and combines them into one signal.
The circuit in the latter stage of 3 includes a gain correction unit 15, a distortion correction unit 16,
The distortion correction RAM 17 and the A / D conversion unit 18 can be shared to form one system. Therefore, the structure is simplified and the economical efficiency can be improved.

Moreover, since the image is read by the dot-sequential method, the reading time can be shortened as compared with the area-sequential method, and there is no color shift unlike the line-sequential method.

[0024]

As described above in detail, according to the present invention, in the case of using the dot-sequential system, the circuit section for processing the sensor output can be one system, the circuit configuration can be simplified, and the economical efficiency can be improved. It is possible to provide a color image reading device that can be used.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an output signal waveform of each unit in the embodiment.

FIG. 3 is a diagram showing an output signal waveform of one pixel from each unit in the embodiment.

FIG. 4 is a diagram for explaining image reading by each of a frame sequential method, a line sequential method, and a dot sequential method.

FIG. 5 is a block diagram showing a conventional example.

[Explanation of symbols]

 12 ... Photoelectric conversion circuit, 13 ... Analog switch, 18 ... A / D converter.

Claims (1)

[Claims] 1. A photoelectric conversion circuit for simultaneously reading three primary colors of red, green, and blue from an original by a dot-sequential method using a sensor, and each color signal from the photoelectric conversion circuit is time-divided and output for each pixel. A color image reading apparatus comprising: a time-division control unit that performs the above-described operation;