JPH0595491A - Picture input device - Google Patents

Abstract

PURPOSE:To simplify a processing circuit after a gain amplifier 22a by amplifying an analog signal of three colors red, green, blue outputted from a CCD line sensor with one gain amplifier at a different amplification factor independently. CONSTITUTION:A CCD line sensor 10 outputs red, green, blue color signals and clamp circuits 20R, 20G, 20B eliminate an undesired signal from an output signal of each color and output signals of each color from the clamp circuits 20R, 20G, 20B are synthesized by a multiplexer 21. The synthesized output is amplified by one gain amplifier to change an amplification factor of the gain amplifier to each color and the gain amplifier amplifies the signal from the multiplexer 21 with the revised amplification factor and the amplified analog signal is converted into a digital signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention displays images in R, G, and B.
The present invention relates to an image input device that converts the output of a CCD line sensor that converts various kinds of electric signals into digital signals and performs various processing.

[0002]

2. Description of the Related Art In recent years, color (multicolor) demands for facsimiles, copying machines, optical filings, etc. have been increasing, and the number of devices equipped with color CCD line sensors is rapidly increasing. Looking at the color CCD line sensor, a contact type in which R, G, B pixels are arranged in time series and a reduced type 3 line in which R, G, B filters are applied to each line are commercially available from each manufacturer. It supports colorization.

Along with this, the processing circuit portion that receives the analog signal output of the CCD line sensor is also hybridized, LS.
With the advancement of I, advanced processing and higher definition have been spurred into the color era.

In such a device, since the analog signals for a plurality of colors output from the CCD line sensor are amplified by different gain amplifiers, variations due to temperature drift of individual gain amplifiers and linearity of input / output. Considering this, three processing circuits are required thereafter, and there is a problem that the circuit configuration becomes complicated.

[0005]

As described above, since the analog signals for a plurality of colors output from the photoelectric conversion means are amplified by different amplifying means respectively, three processing circuits are required thereafter, There is a problem that the circuit configuration becomes complicated.

Therefore, according to the present invention, an analog signal for a plurality of colors output from the photoelectric conversion means can be independently amplified by one amplification means with different amplification factors, and a processing circuit after the amplification means. An object of the present invention is to provide an image input device capable of simplifying.

[0007]

An image input device of the present invention is a photoelectric conversion means for outputting color signals of at least two colors, and a removal for removing unnecessary signals from output signals for each color from the photoelectric conversion means. Means, synthesizing means for synthesizing the output signals for each color from the removing means, one amplifying means for amplifying the output from the synthesizing means, changing means for changing the amplification factor of the amplifying means for each color, and this change The amplification means is composed of processing means for amplifying the signal from the synthesizing means with the amplification factor changed by the means, and conversion means for converting the signal processed by the processing means from an analog signal to a digital signal. ..

The image reading apparatus of the present invention detects the reflected light of the light radiated by the light irradiating means for irradiating the original placed on the original table with the light and the photoelectric conversion processing. By doing so, a photoelectric conversion unit that outputs color signals of at least two colors, a removal unit that removes unnecessary signals from the output signal of each color from this photoelectric conversion unit, and an output signal of each color from this removal unit are output. The synthesizing means for synthesizing, one amplifying means for amplifying the output from the synthesizing means, changing means for changing the amplification factor of the amplifying means for each color, and the amplification factor changed by the changing means, It is composed of processing means for amplifying the signal from the combining means, and conversion means for converting the signal processed by this processing means from an analog signal to a digital signal.

[0009]

According to the present invention, at least two or more color signals are output by the photoelectric conversion means, unnecessary signals are removed from the output signals for each color by the removing means, and the output signals for each color from the removing means are output. The synthesizing means synthesizes the synthesized output, the one amplifying means amplifies the amplified output, and the amplifying rate of the amplifying means for each color is changed. The signal is amplified, and the amplified signal is converted from an analog signal to a digital signal.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a view showing the schematic arrangement of a scanner according to an embodiment of the image reading apparatus of the present invention. This scanner reads a document placed on a document table and outputs the read image signal to an external device such as a computer.

An operation panel (not shown) is provided on the front portion of the upper part of the scanner body 1, and an original placing table (platen glass) 2 made of transparent glass is fixed to the upper surface of the operation panel. An openable and closable original cover 1a is provided near the original table 2. A document scanning unit 3 for optically scanning and reading a document G placed on a document table 2 is provided above the scanner body 1. The original scanning unit 3 includes a first carriage 5 having an illumination lamp 4 for irradiating the original G with light, a mirror 6 for bending the optical path, a second carriage 8 having a mirror 7, a condenser lens block 9, It has a photoelectric converter 10 which receives reflected light from the document G guided through the optical paths of these respective parts and forms an image on the surface.

The first carriage 5 includes, in addition to the illumination lamp 4, a reflector as a reflecting mirror that collects the light from the illumination lamp 4 on the surface of the original document and a second reflected light from the original G.
A mirror 5 that guides the carriage 8 side is mounted.

First carriage 5 and second carriage 8
Are connected to each other by a timing belt (not shown), and can reciprocate in the direction of arrow a along the lower surface of the document table 2. In this case, the second carriage 8 moves in the same direction at half the speed of the first carriage 5, so that the optical path length up to the lens block 9 can be kept constant. You can

The first carriage 5 and the second carriage 8 are each driven by a stepping motor.

The photoelectric converter 10 uses a color CCD line sensor having a plurality of photoelectric conversion elements arranged in rows, for example, a charge coupled device (CCD).

In this CCD line sensor 10, one pixel is composed of photoelectric conversion elements for red, green and blue (R, G, B), and 3 pixels for red, green and blue (R, G, B).
The color signal of the color is output.

Further, the scanner body 1 has a CCD
A processing circuit 11 that performs signal processing for converting the output signal of the line sensor 10 into a stable digital signal is provided.

FIG. 1 is a block diagram schematically showing the structure of the processing circuit 11.

That is, the CCD line sensor 10,
Clamp circuits 20R, 20G, 20B, multiplexer (MPX) 21, gain amplifier section 22, RGB switching timing generation circuit 23, sample hold circuit 24, A
/ D conversion circuit 25 and various timing generation circuits 26
It is composed by.

The CCD line sensor 10 is supplied with two types of transfer clocks, reset pulses, shift pulses and the like from various timing generation circuits 26.

The CCD line sensor 10 outputs red, green, and blue (R, G, B) analog signals according to these supplied signals. That is, an analog signal as shown in (d) of FIG. 3 is output with respect to the signals shown in (a) to (c) of FIG.
This analog signal is the same for red, green, and blue (R, G, B). A DC output voltage (VOS) of 4 to 5 V is added to the analog signal and is output. In the case of a light shield pixel having no incident light, the output voltage (V
DRK) In the case of an effective pixel with incident light, the actual effective signal part is the part obtained by subtracting the dark output voltage (VDRK) and the DC output voltage (VOS) from the output signal (effective signal part). ..

As a result, from the CCD line sensor 10, the red, green and blue (R,
G, B) analog signals are output and supplied to the clamp circuits 20R, 20G, and 20B, respectively.

The clamp circuits 20R, 20G and 20B are
Red output from each CCD line sensor 10,
Corresponding to the green and blue (R, G, B) analog signals, the dark output voltage (VDRK) described above from the supplied analog signals
Is a circuit for subtracting the DC output voltage (VOS) from each other, and clamp signals for each color shown in (d) to (f) of FIG. 4 are output.

The clamp circuits 20R, 20G and 20B are respectively supplied with clocks for clamping from various timing generating circuits 26. The outputs of the clamp circuits 20R, 20G and 20B are multiplexers (MP
X) 21.

The clamp circuits 20R, 20G and 20B are
Each color signal (R, R output from the CCD line sensor 10)
The DC output voltage of G and B) is different from the dark output voltage, and the dark output voltage is characterized by increasing as the temperature of the CCD line sensor 10 rises. It is necessary to install it independently.

The multiplexer 21 includes a clamp circuit 20.
R for analog signals for each color from R, 20G, 20B
The synthesis is performed using the timing signal from the GB switching timing generation circuit 23, and a signal as shown in FIG. 4 (g) is output. The combined signal from the multiplexer 21 is output to the gain amplifier unit 22.

The gain amplifier section 22 includes a multiplexer 2
A signal for each color in the composite signal from 1 is amplified with different amplification factors corresponding to each color according to a gain select signal as a timing signal from the RGB switching timing generation circuit 23, and the amplification is performed. The result is shown in FIG. 4 (h).

As shown in FIG. 5, the gain amplifier section 22 includes a gain amplifier 22a, a resistor r0, a variable resistor VRR,
It is composed of VRG, VRB, and changeover switches SWR, SWG, and SWB. The gain of the gain amplifier 22a is
The red signal is determined by the variable resistor VRR and the resistor r0 (1+ (VRR / r0)), and the green signal is determined by the variable resistor VRG and the resistor r0 (1+ (VRG / r0)), the blue signal is determined by the variable resistor VRB and the resistor r0 (1+ (VRB
/ R0)).

When the changeover switch SWR is turned on by the R gain select signal from the RGB changeover timing generation circuit 23 for the red signal, the amplification factor of the gain amplifier 22a becomes (1+ (VRR / r0)), and the green color. When the changeover switch SWG is turned on by the G gain select signal from the RGB changeover timing generation circuit 23 for the signal of, the amplification factor of the gain amplifier 22a becomes (1+ (VRG / r0)), and for the blue signal. R
When the changeover switch SWB is turned on by the B gain select signal from the GB changeover timing generation circuit 23, the amplification factor of the gain amplifier 22a becomes (1+ (VRB / r
0)).

The variable resistors VRR, VRG, VRB can be adjusted in response to variations in sensitivity due to different lots of the CCD line sensor 10, variations due to different lots of light sources, and a decrease in light amount due to the passage of time. ..

The RGB switching timing generating circuit 23
According to the reference clock and the synchronizing signal shown in FIG. 6A supplied from the various timing generation circuits 26,
Is a circuit for outputting a gain select signal for each color as shown in (b) to (d).

The reference clock is synchronized with the reference clock used for output to the CCD line sensor 10, and the synchronization signal is the same as the shift pulse output to the CCD line sensor 10.

The signal from the gain amplifier section 22, that is, the gain amplifier 22a is supplied to the sample hold circuit 24.

The sample-hold circuit 24 samples and holds the peak value of the signal supplied from the gain amplifier 22a by the sample-hold pulse shown in FIG. (J) is output, and this output is supplied to the A / D conversion circuit 25.

The A / D conversion circuit 25 converts the sample-hold signal supplied from the sample-hold circuit 24 from an analog signal into a digital signal by using a clock for A / D conversion supplied from various timing generation circuits 26. It is a circuit to convert.

The digital signal from the A / D conversion circuit 25 is output to the image processing circuit (not shown) in the subsequent stage.

The various timing generation circuits 26 are connected to the CC
D line sensor 10, clamp circuits 20R, 20G, 2
0B, an RGB switching timing generation circuit 23, a sample hold circuit 24, and an A / D conversion circuit 25 respectively output timing signals such as clocks.

Next, the operation in such a configuration will be described. That is, the CCD line sensor 10 corresponds to the transfer clock, the reset pulse, the shift pulse, and the like from the various timing generation circuits 26, as shown in FIGS.
The red, green and blue (R, G, B) analog signals shown in
It outputs to each of the clamp circuits 20R, 20G, and 20B.

The clamp circuit 20R outputs the dark output voltage (V) from the red signal supplied from the CCD line sensor 10.
DRK) and the DC output voltage (VOS) are subtracted to output a signal ((d) in FIG. 4) to the multiplexer 21, and the clamp circuit 20G outputs a dark signal from the green signal supplied from the CCD line sensor 10 VDRK) and DC output voltage (V
A signal obtained by subtracting OS) ((e) in FIG. 4) is output to the multiplexer 21, and the clamp circuit 20B outputs the dark output voltage (VDRK) and the DC output voltage (from the blue signal supplied from the CCD line sensor 10). A signal ((f) in FIG. 4) obtained by subtracting VOS) is output to the multiplexer 21.

The multiplexer 21 includes the clamp circuit 20.
The signals supplied from R, 20G, and 20B are combined using the timing signal from the RGB switching timing generation circuit 23 ((g) of FIG. 4), and this combined signal is output to the gain amplifier 22a of the gain amplifier unit 22. ..

Further, the gain select section 22 is supplied with a gain select signal for each color from the RGB switching timing generating circuit 23.

As a result, the gain amplifier section 22 becomes RG
When the R gain select signal from the B switching timing generating circuit 23 is supplied, the changeover switch SWR is turned on, so that the amplification factor (1+ (VRR / r0)) determined by the variable resistor VRR and the resistor r0 is obtained. Gain amplifier 2
2a, and the red signal R in the signal supplied from the multiplexer 21 by the gain amplifier 22a at this amplification factor.
Amplify the one corresponding to.

Further, the gain amplifier section 22 is determined by the variable resistor VRG and the resistor r0 when the changeover switch SWG is turned on when the G gain select signal from the RGB switching timing generating circuit 23 is supplied. The amplification factor (1+ (VRG / r0)) is set in the gain amplifier 22a, and the gain amplifier 22a amplifies the signal corresponding to the green signal G among the signals supplied from the multiplexer 21 at this amplification factor.

Further, the gain amplifier section 22 is determined by the variable resistor VRB and the resistor r0 by turning on the changeover switch SWB when the B gain select signal from the RGB switching timing generating circuit 23 is supplied. The amplification factor (1+ (VRB / r0)) is set in the gain amplifier 22a, and the gain amplifier 22a amplifies the signal corresponding to the blue signal B among the signals supplied from the multiplexer 21 at this amplification factor.

Therefore, the gain amplifier 22a is amplified differently for each color and the peak values are made uniform.
The signal as shown in (h) of FIG.
Is output to.

The sample-hold circuit 24 samples and holds the peak value of the signal supplied from the gain amplifier 22a by the sample-hold pulse shown in FIG. A signal as shown in (j) is output to the A / D conversion circuit 25.

The A / D conversion circuit 25 converts the sample / hold signal supplied from the sample / hold circuit 24 from an analog signal into a digital signal by using a clock for A / D conversion supplied from various timing generation circuits 26. It is converted and output to an image processing circuit (not shown) in the subsequent stage.

In this embodiment, one gain amplifier is used to amplify and process signals of each color of red, green, and blue by different amplification factors, and each color is independently processed as in the conventional case. Unlike the one in which the gain amplifier is provided, the circuit configuration can be simplified and the cost can be reduced.

Further, in the case of using a plurality of gain amplifiers, the problem that the temperature drift and the difference in the linearity of the output with respect to the input occur will occur.
By using one gain amplifier, there is no difference in temperature drift or linearity, so red, green,
It is possible to minimize variations in the analog signal portion of each blue signal and perform accurate processing.

[0051]

As described in detail above, according to the present invention,
Image input capable of independently amplifying analog signals for a plurality of colors output from the photoelectric conversion means with different amplification factors by one amplification means, and simplifying a processing circuit after the amplification means A device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a processing circuit of an image input apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view schematically showing the configuration of the image input device in FIG.

FIG. 3 is a diagram showing a signal waveform of a main part of the processing circuit of FIG.

FIG. 4 is a diagram showing a transfer clock, a reset pulse, and an output waveform in the CCD line sensor of FIG.

5 is a diagram showing a circuit configuration of a gain amplifier unit in FIG.

FIG. 6 is a diagram for explaining a gain select signal in the gain amplifier section of FIG.

[Explanation of symbols]

1 ... Scanner main body, 2 ... Document table, 3 ... Document scanning unit, 4 ...
Illumination lamp, 10 ... CCD line sensor, 11 ... Processing circuit, 20R, 20G, 20B ... Clamp circuit, 21 ... Multiplexer, 22 ... Gain amplifier section, 22a ... Gain amplifier, 23 ... RGB switching timing circuit, 24 ... Sample hold circuit , 25 ... A / D conversion circuit Various timing generation circuits.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Gen Nakamura, 70 Yanagicho, Saiwai-ku, Kawasaki-shi, Kanagawa Toshiba Yanagimachi factory Technology Co., Ltd.

Claims (2)

[Claims] 1. A photoelectric conversion unit that outputs color signals of at least two colors, a removal unit that removes an unnecessary signal from an output signal for each color from the photoelectric conversion unit, and a removal unit for each color from the removal unit. The combining means for combining the output signals, one amplifying means for amplifying the output from the combining means, the changing means for changing the amplification factor of the amplifying means for each color, and the amplification factor changed by the changing means An image input device comprising: processing means for amplifying the signal from the combining means by the amplifying means; and conversion means for converting the signal processed by the processing means from an analog signal to a digital signal. .. 2. A light irradiating means for irradiating a document placed on a document table with light, and at least photoelectric conversion processing by detecting reflected light of light radiated by the light irradiating means. A photoelectric conversion unit that outputs color signals of two or more colors, a removal unit that removes an unnecessary signal from the output signal of each color from the photoelectric conversion unit, and a synthesis that synthesizes the output signal of each color from the removal unit. Means, one amplifying means for amplifying the output from the synthesizing means, changing means for changing the amplification factor of the amplifying means for each color, and the amplifying means with the amplification factor changed by the changing means. An image reading apparatus comprising: a processing unit that amplifies a signal from the combining unit; and a conversion unit that converts the signal processed by the processing unit from an analog signal to a digital signal.