JPH1155465A - Image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read an image at high speed and to reproduce the image with high precision by simultaneously or almost simultaneously lighting three kinds of light sources so as to illuminate an original, and receiving reflection lights from the original by three kinds of photodetectors which receive light of respective colors in charge. SOLUTION: The red color, green color and blue color photodetectors 1R, 1G and 1B outputting signals corresponding to light receiving quantities are made to be an arrayal where the same kinds of plural photodetectors are entwined and multiple photodetectors are arranged in a line shape. When the three kinds of light sources R, G and B are simultaneously lighted and the surface of the original (k) on a glass plate 3 is irradiated with a white light, the reflection lights are received by the respective photodetectors 1R, 1G and 1B of the three photodetector arrayals NR, NG and NB. A second reading operation is executed while feeding the original (k), the reading operation is continuously executed while feeding paper afterwards in a same way and the reflection lights from the original (k) are respectively received by the respective photodetectors.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus suitable for reading a document image in color.

[0002]

2. Description of the Related Art As is well known, red (R) and red (R)
There is a configuration including three types of light sources that emit green (G) and blue (B) light. In this image reading device,
For example, these light sources are sequentially switched and turned on in the order of R, G, and B, and the reflected light from the original of the light emitted from each light source is sequentially received by one type of light receiving element in the order of R, G, and B. It is configured as follows. The reflected light of each color received by the light receiving element is serially output in the order of R, G, and B as a signal corresponding to the amount of reflected light of each color by a phototransistor constituting the light receiving element. You.

[0003]

For example, in an image reading apparatus of a type in which an image is read for each line and each light source R, G, B is sequentially switched in a predetermined order and turned on, each line is After each irradiation of light of each color of R, G and B, the next line must be read. That is, three light sources are used for each line.
This operation must be turned on and off again, and this operation has hindered the speeding up of image reading.

Further, in the image reading apparatus having the above configuration, since signals of respective colors are serially output, color mixing occurs due to the remaining charges in the phototransistor. That is, if the signals of the respective colors are serially output in the order of R, G, and B corresponding to the image reading order, even if the R signal is output, the R signal (charge) is sufficient. The remaining R signal and the G signal to be output will be mixed when the G signal is output next time since the G signal is not discharged but remains in the phototransistor. Similarly, when the B signal is output next, the remaining G signal and the B signal to be output are mixed. As described above, in the image reading apparatus of the type in which the R, G, and B signals are sequentially and serially output from the phototransistor, a signal to be output before remains and is mixed with a signal to be output next, The image of the read document cannot be faithfully reproduced. In addition, the higher the remaining rate of the signal to be output earlier, the lower the saturation of the reproduced image is, and the color of the reproduced image approaches gray.

According to the inventors of the present invention, there is a relationship as shown in FIG. 9 between the output voltage (dynamic range) from the phototransistor and the residual ratio of charges in the phototransistor, that is, It has been confirmed that the smaller the output voltage, the higher the charge remaining rate. The small output voltage means that the image of the scanned document is dark,
It means that the brightness is low, such an image (pixel)
In particular, when reading is performed, the degradation of the chroma of the reproduced image is particularly conspicuous.

The present invention was conceived under the circumstances described above, and realizes high-speed image reading and reproduces an image with high accuracy without deteriorating the saturation of a reproduced image. Is to be able to do this.

[0007]

DISCLOSURE OF THE INVENTION In order to solve the above problems, the present invention employs the following technical means.

That is, the image reading device provided by the first aspect of the present invention is an image reading device provided with three types of light sources that emit red, green, and blue light, respectively. A plurality of three types of light receiving elements for red, green, and blue are provided, each of which outputs a signal corresponding to the amount of received light of each color of blue, and the three types of light sources are turned on simultaneously or substantially simultaneously. It is characterized in that a white light is applied to the original and that the light receiving element receives the light of the color in charge of each of the reflected light from the original.

According to the above arrangement, red (R), green (G),
By turning on these light sources simultaneously instead of sequentially turning on the light sources that emit blue (B) light, it is possible to realize high-speed image reading.
That is, in the conventional image reading apparatus having three types of light sources, for example, when reading an image line by line, it is necessary to repeat lighting and extinguishing three times for each line. Lighting the respective light sources simultaneously without repeating the lighting / extinction of the respective light sources,
Each of the light receiving elements capable of receiving only the light of a predetermined color can receive the reflected light of each color at the same time. Therefore, as compared with the case where the image is read sequentially for each color, it is advantageous because it is configured to read each color at the same time, and it is possible to realize high-speed image reading.

The three types of light sources are simultaneously turned on to produce white light, and the light illuminated and reflected on the original is received by three types of light receiving elements which receive light for each color. However, if the three types of light receiving elements are configured to receive light of each color in this way,
Signals can be output in parallel for each color. That is, as in an image reading apparatus configured to sequentially switch the light source and sequentially read an image for each color, and sequentially output a signal of each color in serial, the image data of the color that has been read previously is received by the light receiving device. It does not remain in the element and mix with the data of the color to be output next. Therefore, in the image reading device having the above configuration, the output data of each color is prevented from being mixed with each other, and it is expected that the reproducibility of the read image is improved.

The image reading device provided by the second aspect of the present invention uses a white LED as a light source,
For red, green, and blue light, which receive light emitted from the light source and reflected from a desired document and output a signal corresponding to the amount of received light of each color of the reflected light, red, green, and blue. It is characterized in that a plurality of three types of light receiving elements are provided.

According to the above arrangement, since the monochromatic light source is used and the respective light receiving elements for receiving the reflected light of the predetermined color are provided, the above three types of light sources are simultaneously turned on. Similarly to the above, it is needless to say that the speed of image reading can be increased, and the reproducibility of the read image is expected to be improved. In the present invention, a white LED is used as the light source. However, since the white LED is cheaper than the case where the above three types of light sources are used, the manufacturing cost of the image reading apparatus can be reduced. It has such advantages.

An image reading apparatus according to a third aspect of the present invention is the image reading apparatus according to the first or second aspect, wherein the plurality of light receiving elements are a plurality of light receiving elements of the same type. The elements are arranged in the main scanning direction, and different types of light receiving elements are arranged in the sub scanning direction.

According to the above configuration, a total of three light receiving elements arranged in the sub-scanning direction can be used as a basic unit corresponding to one pixel of a read image. For this reason, the width of these light receiving elements in the main scanning direction can be formed to be substantially equal to the width of one pixel of the read image. The three types of light receiving elements arranged in the sub-scanning direction can receive reflected light from the original by transferring the light receiving elements or the original in the sub-scanning direction. Since the light-receiving elements are arranged in the sub-scanning direction, it is not necessary to make the width in the sub-scanning direction between the light-receiving elements so small. Therefore, in the present invention,
The output of the image signal output from each light receiving element can be increased by the amount by which the width of each light receiving element, particularly in the main scanning direction, can be increased and the light receiving area of each light receiving element can be increased.

In a preferred embodiment, output level adjusting means for equalizing the output levels of the signals output from the three types of light receiving elements are provided.

The above three types of light receiving elements may have different output levels of the signals output from the respective light receiving elements even when the same amount of light is received, for example. In some cases, the read image cannot be faithfully reproduced.
Therefore, if the output levels of the signals output from the respective light receiving elements are made uniform, as in the present invention, the read image can be faithfully reproduced. The output level adjusting means may be provided, for example, by providing a variable resistor on a wiring for transmitting an output signal formed on a substrate on which the light receiving element is formed, and adjusting a resistance value of the variable resistor. Can be realized.

In a preferred embodiment, image data of each color is read in parallel while the light source of each color or the white LED is continuously turned on during or almost during reading of an image of one document. It is configured as follows.

As described above, it is possible to realize high-speed image reading by turning on three types of light sources at the same time or by using a white LED as a light source. Is configured so that the image is read while being continuously lit during or almost during the reading of the image of one document,
Since there is no need to repeatedly turn on and off the light source,
The time required for disappearance can be reduced, and the speed of image reading can be further increased. Of course, as described above, if the image data of each color is read in parallel and the data of each color is output in parallel, the image data of the previously read color remains in the light receiving element. Color mixing can be avoided.

In a preferred embodiment, three lines of the original in the sub-scanning direction are used as a basic unit, and the basic unit is irradiated with white light to read different colors for each line. It is configured such that the reading is sequentially performed until the reading of one document is completed by shifting by one line.

According to the above configuration, actually, image reading is performed three times for each line.
Since the reading of the image of each color is performed simultaneously with the line unit as a basic unit, as a result, the image data of each color is read simultaneously for each line in the image reading apparatus configured to read the image line by line. Is the same as For this reason, in the image reading apparatus having the above-described configuration, it is theoretically possible to perform image reading at approximately three times the speed as compared with the case where three types of light sources are sequentially switched for each line to perform image reading three times. It is possible to realize high-speed image reading.

[0021] Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing an example of the image reading apparatus according to the present invention. FIG. 2 is an assembled sectional view of the image reading device. FIG.
FIG. 3 is a sectional view taken along the line III. FIG. 4 is a plan view of a circuit board on which an image sensor chip and three types of light sources mounted on the image reading device are mounted. FIG.
FIG. 3 is a plan view of a main part showing an arrangement of a plurality of light receiving elements. FIG. 6 is a circuit block diagram illustrating an example of a circuit configuration of the image sensor chip. FIG. 7 is a circuit block diagram showing an example of output level adjusting means for adjusting the output level of the signal output from the image sensor chip. In the present embodiment, an image reading apparatus configured as a contact type will be described as an example.

As shown in FIGS. 1 and 2, the image reading apparatus A includes a case 2, a glass plate 3, a circuit board 4,
The light guide unit 6A and the lens array 9 are provided. The circuit board 4 has three light sources R,
G, B and a plurality of image sensor chips 5 are mounted. As described later, each of the image sensor chips 5 includes a plurality of three types of light receiving elements 1R, 1G, and 1B that sense red light, green light, and blue light, respectively.

As best shown in FIG. 1, the case 2 is made of, for example, a synthetic resin and is formed in a relatively elongated box shape extending in a certain direction. The glass plate 3 is
A document (not shown) to be read is disposed on the front surface (upper surface) of the case 2 so as to face the document, and is fitted into the upper portion of the case 2 so as to close the upper opening of the case 2. A platen roller (not shown) that can be driven and rotated is disposed at a position facing the surface of the glass plate 3, and a document is sandwiched between the platen roller and the surface of the glass plate 3, and the platen roller is driven to rotate. As a result, it is transported in a predetermined sub-scanning direction (left-right direction in FIG. 2). In the present embodiment, the document transport is intermittent transport at a constant pitch. However, the present invention is not limited to this, and it is also possible to read a document image while performing continuous transport.

As shown in FIGS. 2 and 3, the light guide unit 6A is formed of a light guide member 6 formed of an acrylic transparent resin such as PMMA and a white resin having excellent light reflectance. It is configured to include a first reflection member 7 and a second reflection member 8, and is accommodated and arranged in the case 2 by means such as press fitting.

As shown in FIGS. 1 to 3, the light guide member 6 has an elongated bar shape, and the upper surface thereof is a light emitting surface 34.
And a light incident portion 33 is formed on the lower surface. The lower surface of the light guide member 6 is a diffuse reflection surface, and any other side surface except the lower surface is preferably a mirror surface. 1 and 3, a central portion in the longitudinal direction of the light exit surface 34 of the light guide member 3 is recessed in a substantially V-shape when viewed from the front. Light sources R, G, and B are arranged below the entrance. Light emitted from these light sources R, G, and B enters the light guide member 6 from the light incident portion 33 and travels while reflecting the longitudinal direction of the light guide member 6 on each side surface. The light emission surface 34 is configured to be emitted from the entirety. The configuration of the light guide member 6 is not limited to the above-described configuration, and may be appropriately changed in design. For example, light is incident from an end of the light guide member 6 and light is emitted from the entire light exit surface 34. Such a configuration may be adopted.

The first and second reflecting members 7 and 8 are in close contact with the side surfaces of the light guide member 6 extending in the longitudinal direction, and reflect light leaked from the light guide member 6 to the outside on the surface. Then, the light is returned into the light guide member 6.
That is, by bringing the respective reflection members 7 and 8 into close contact with the light guide member 6, the light incident into the light guide member 6 is efficiently emitted from the light emission surface 34.

The lens array 9 has a plurality of selfoc lenses 90 respectively held in a block-shaped lens holder 91 extending in the main scanning direction. The plurality of selfoc lenses 90 are arranged in a row in the main scanning direction. It is arranged in a shape. The lens array 9 is provided between a region of the glass plate 3 to which light is irradiated and the image sensor chip 5, and reflects light reflected from an original placed on the glass plate 3 to the image sensor chip 5. 5 and serves to focus light on the plurality of light receiving elements 1R, 1G, and 1B. In this case, an original image is formed on each of the light receiving elements 1R, 1G, and 1B at the same erect magnification.

The circuit board 4 has a configuration in which the two attachments 25 are fitted from below the case 2.
Engagement projections 26 and 2 provided on the outer surface of case 2
6 to be attached. As shown in FIG. 4, the circuit board 4 has connector terminal portions 40 for making electrical wiring connections with external devices.
Is provided, and a red LED,
Three types of light sources R consisting of a green LED and a blue LED,
G, B and a plurality of image sensor chips 5 are mounted. As the light source, three types of light sources R,
Instead of G and B, one or more so-called white LEDs may be used.

As shown in FIG. 5, each of the image sensor chips 5 has a light receiving element 1R for red light and a light receiving element 1G for green light on an upper surface of a chip-shaped substrate 50 having a rectangular shape in plan view. , And a large number of light receiving elements 1B for blue light are arranged in a predetermined state. The three types of light receiving elements 1R, 1G, and 1B are basically constituted by phototransistors exhibiting a photoelectric conversion function, and their surfaces are covered with a color filter of a predetermined color. Has become. That is, the light receiving element 1R for red light has a surface covered with a red filter, receives red light of a predetermined wavelength transmitted through the red filter, and has an analog image of a voltage level corresponding to the amount of received light. It is configured to output a signal. Similarly, the light receiving element 1G for green light is covered with a green filter, and the light receiving element 1B for blue light is covered with a blue filter, respectively, which receives green light or red light passing through each filter. An image signal of a voltage level corresponding to the amount of received light is output.

The above three types of light receiving elements 1R, 1G, 1B
Are arranged as follows in relation to the chip-shaped substrate 50. That is, the above three types of light receiving elements 1R,
1G and 1B are arranged such that a plurality of light receiving elements of the same type are put together and arranged in a row in the longitudinal direction of the chip-shaped substrate 50, and only the light receiving element 1R for red light is arranged. Light receiving element array NR, light receiving element 1 for green light
There are provided a total of three light receiving element arrays NG in which only G is arranged and a light receiving element array NB in which only the light receiving element 1B for blue light is arranged. When the three light receiving element rows NR, NG, and NB are viewed in the lateral direction of the chip-shaped substrate 50, three types of light receiving elements 1R,
1G and 1B are arranged regularly. Also,
The arrangement order of the plurality of light receiving elements in the lateral direction of the chip-shaped substrate 50 is, for example, a light receiving element 1R for red light.
The order is such that the light receiving element 1G for green light is located between the light receiving element 1G and the light receiving element 1B for blue light.

The number of light receiving elements in each of the light receiving element rows NR, NG, NB is, for example, 120, and the pitch p1 between the light receiving elements in the longitudinal direction of the chip-shaped substrate 50 is:
For example, when reading at a reading density of 8 dots / mm, it is 125 μm. On the other hand, the light receiving element rows NR,
The pitch p2 between the light receiving elements in the lateral direction of the NG and NB chip-shaped substrates 50 is preferably an integer multiple of the pitch p1, and in the present embodiment, p1 = p2.

A plurality of the image sensor chips 5 are mounted side by side on the upper surface of the circuit board 4 and the plurality of image sensor chips 5 are mounted on the image reading device A.
Are arranged in series in the main scanning direction. In this case, the image sensor chips 5 are arranged so that the longitudinal direction of the chip-shaped substrate 50 is the main scanning direction. Therefore, the plurality of light receiving elements 1R, 1G, and 1B of each image sensor chip 5 form a row in which the light receiving element rows NR, NG, and NB extend in the main scanning direction, and have three types in the sub scanning direction. Light receiving elements 1R, 1G, 1B
Are arranged in a large number of rows. When the image reading device A is configured to be able to read a document having a reading density of, for example, 8 dots / mm and an A4 width, the number of light receiving elements in each of the light receiving element rows NR, NG, and NB is 120. A total of 20 image sensor chips 5 are arranged on the circuit board 4.

As shown in FIG.
The top 5 has a shift register 21 and a chip select circuit.
22, 120 red light receiving elements 1R for red light
Transistor PTR₁~ PTR₁₂₀, 120 green
Phototransistor PTG constituting light receiving element 1G for light
₁~ PTG₁₂₀, 120 light receiving elements 1B for blue light
Constituting phototransistor PTB₁~ PTB₁₂₀, 12
0 first field effect transistors FETR for red light
₁~ FETR₁₂₀, First field effect for 120 green lights
Result transistor FETG₁~ FETG₁₂₀, 120
First field effect transistor FETB for blue light₁~ F
ETB₁₂₀, The second field effect transistor F for red light
ETR₂₀₁, The second field effect transistor F for green light
ETG_{20 1}Second field effect transistor FE for blue light
TB₂₀₁, Third field effect transistor FE for red light
TR₂₁₁, Third field effect transistor FE for green light
TG₂₁₁, Third field effect transistor FE for blue light
TB₂₁₁, Operational amplifier OPR for red light₁For green light
Operational amplifier OPG₁, OPB for blue light ₁,
Resistor RR for red light₁~ RR_Three, Green light resistor R
G₁~ RG_Three, Resistor RB for blue light₁~ RB_Three, And
And 11 pads SI, CLK, GND, AOR1, A
OR2, SO, AOG1, AOG2, AOB1, AOB
2, VDD is formed. Note that the first field effect transistor
Transistor FETR₁~ FETR₁₂₀, FETG₁~ F
ETG₁₂₀, FETB₁~ FETB₁₂₀, The second electric field effect
Fruit transistor FETR₂₀₁, FETG₂₀₁, FETB
₂₀₁, And third field effect transistor FET
R₂₁₁, FETG₂₁₁, FETB₂₁₁Is MO
It is an S-type field effect transistor.

The pad SI receives a serial-in signal. To the pad CLK, for example, a clock signal of 8 MHz is input from the outside of the circuit board 4 via the connector terminal portion 40 or the like. The pad GND is connected to the ground-in. An analog image signal corresponding to the amount of received red light is serially output from the pad AOR1, and the amplified image signal is output from the pad AOR2. Similarly, an analog image signal corresponding to the amount of received green light is serially output from the pad AOG1.
The amplified image signal is output from AOG2. An analog image signal corresponding to the amount of received blue light is output serially from the pad AOB1, and the amplified image signal is output from the AOB2. From the pad SO,
A serial out signal is output. In the pad VDD,
A power supply voltage of, for example, 4 V is supplied from outside the circuit board 4 via the connector terminal section 40 or the like.

At the time of actual reading of an original, for example, 8M is applied to the pad CLK of the image sensor chip 5.
The clock signal of Hz is supplied, and the serial-in signal is supplied to the pad SI of the image sensor chip 5 of the first stage among the 20 image sensor chips 5. The serial-in signal input to the pad SI of the image sensor chip 5 in the first stage is input to the set terminal of the chip select circuit 22, and the chip select circuit 22 outputs from the select signal output terminal in synchronization with the clock signal. The selected signal to high level. This select signal is a signal obtained by inverting the clock signal,
Second field effect transistor FETR for each of green and blue colors
_201, FETG _201, because it is supplied to the gate of FETB _201, each of the second clock signal period of the low level
Field effect transistor FETR ₂₀ of _1, FETG _201,
FETB ₂₀₁ will be turned on.

Also, the serial-in signal is a shift register.
The clock signal is also supplied to the input terminal of the
At the timing of the shift, the first stage bit of the shift register 21
It is taken in. Thereby, the first shift register 21
The first bit for the red, green, and blue colors, with the stage bit on
Effect transistor FETR₁, FETG₁, FETB ₁
A high-level signal is input to the gates of the first and second electric fields.
Effect transistor FETR₁, FETG₁, FETB₁
Turns on. At this time, the clock signal is low level.
Therefore, the third field effect transistor for each of the colors red, green and blue
Star FETR_{twenty one 1}, FETG₂₁₁, FETB₂₁₁Is off
And a phototransistor PT for each color of red, green and blue
R₁, PTG₁, PTB₁Current due to charge stored in
Is the first field effect transistor FETR₁, FETG
₁, FETB₁Through the resistors R for red, green and blue
R_Three, RG_Three, RB_ThreeFlows to These resistors R
R_Three, RG_Three, RB_ThreeVoltage between red, green and blue
Operational amplifier OPR₁, OPG₁, OPB₁Non-inversion of
Input to the input terminal, and the resistor RR₁, RG₁, RB₁And
Armor RR_Two, RG_Two, RB_TwoIs determined by the ratio of the resistance value to
Pad A for each color of red, green and blue
Analog reading image signal from OR2, AOG2, AOB2
Output as a signal. At this time, the clock signal is
Level and the select signal is high level.
Second field effect transistor FETR₂₀₁, FETG
₂₀₁, FETB₂₀₁Is on. In addition, red, green, blue
From pads AOR1, AOG1, and AOB1 for each color
Is each operational amplifier OPR₁, OPG₁, OPB₁By
An analog read image signal that has not been amplified is output.
You.

The clock signal is changed from low level to high level
Rises, the select signal goes low and
Second field effect transistor FETR₂₀₁, FETG
₂₀₁, FETB₂₀₁Turns off, and each pad AOR2, AO
When no read image signal is output from G2 and AOB2
In each case, each third field-effect transistor FETR₂₁₁,
FETG₂₁₁, FETB₂₁₁Is turned on and each photo
Star PTR₁, PTG₁, PTB₁Of each third
Field effect transistor FETR₂₁₁, FETG ₂₁₁,
FETB₂₁₁Is discharged through. Clock signal is high
When the level falls from low to low, the shift register
The serial-in signal of the first stage bit of 21
And the same operation as for the first stage bit.
Phototransistor PTR for each color of red, green and blue_Two,
PTG_Two, PTB_TwoAnalog according to the charge stored in the
Read signals of red, green, and blue pads AOR2, A
Output from OG2 and AOB2.

Hereinafter, a clock signal is generated by the same operation.
Synchronously, phototransistor PTR for each color of red, green and blue
_Three~ PTR₁₂₀, PTG_Three~ PTG₁₂₀, PTB_Three~ P
TB ₁₂₀Analog read signal according to the charge stored in the
Are pads AOR2, AOG2, A for each color of red, green, and blue
When output from OB2, the falling edge of the next clock signal
Serial from the last bit of the shift register 21
Output signal and the clear signal of the chip selector circuit 3 is output.
The signal is output to the signal input terminal as a clear signal. This
The chip selector circuit 3 sets the select signal to a low level.
keep. Also, the serial out output from the pad SO
The signal is sent to the pad SI of the image sensor chip 5 at the next stage.
Input as a serial-in signal. This allows the next stage
Of the image sensor chip 5 of the first stage
It operates in the same way as the sub chip 5 and synchronizes with the clock signal.
Phototransistor PTR for each color of red, green and blue₁~ PT
R_{12 0}, PTG₁~ PTG₁₂₀, PTB₁~ PTB₁₂₀
An analog read image signal corresponding to the charge stored in the
Pads AOR2, AOG2, AO for each color of red, green and blue
It is sequentially output from B2. This is the last step,
That is, repeated up to the 20th image sensor chip 5
It is.

As shown in FIG. 7, the pads AOR1, AO for each color of each image sensor chip 5 as described above.
The read image signals output from G1, AOB1, AOR2, AOG2, and AOB2 are divided into a non-amplified signal and an amplified signal for each color, and each of the read image signals is serially counted.
The signal is transmitted by the signal lines SL1 to SL6. Variable resistors VR1 to VR6 as output level adjusting means are provided on the signal lines SL1 to SL6, respectively. By adjusting the resistance values of the variable resistors VR1 to VR6, the pads for each color are adjusted. AOR1, AOG
1, AOB1 or AOR2, AOG2, and AOB2 make the output levels of the read image signals uniform.
As described above, in the present embodiment, the output levels of the signals output from the respective image sensor chips 5 are configured to be uniform, and the output levels of the light receiving elements 1R, 1G, and 1B for the respective colors are output. This makes it possible to correct the unevenness of the output level of the signal and reproduce the read image faithfully. In addition, each of the variable resistors VR1 to VR1
6 is formed on the chip-shaped substrate 50, for example.

Next, an example of use and operation of the image reading apparatus A will be described with reference to FIG.

First, as shown in FIG. 8A, an original K is placed on the surface of the glass plate 3 of the image reading device A, and three types of light sources R, G, B are placed on the surface of the original K. Simultaneously light up and emit white light. Then, the reflected light is reflected by the surface of the document K, and then converged by the respective SELFOC lenses 90 of the lens array 9 to the same size as the erect, and each of the light receiving elements of the three light receiving element rows NR, NG, and NB. Light is received by 1R, 1G, and 1B. According to the first reading operation, the light receiving element 1 is placed on the first line L1 of the document K as shown in FIG.
The image signal for the red light is represented by R in the second line L
2 for the green light by the light receiving element 1G, and for the third line L3, the light receiving element 1G.
By B, an image signal for blue light is obtained. In FIGS. 6E to 6H, the portions indicated by black circles indicate portions where image reading has already been performed. As described above, the distance between the three types of light receiving elements 1R, 1G, and 1B in the sub-scanning direction is 125 μm, and therefore, the distance between the reading lines L1, L2, and L3 on the document K in the sub-scanning direction is the same. 125 μm.

Next, as shown in FIG. 5B, after the original K is further fed by 125 μm in the sub-scanning direction, a second reading operation is performed. In the second reading operation, as shown in FIG. 7F, an image signal of red light is provided by the light receiving element 1R for the second line L2 of the document K, and a light receiving element 1G is provided for the third line L3. As a result, an image signal for green light is obtained, and for the fourth line L4, an image signal for blue light is obtained by the light receiving element 1B. Similarly, as shown in FIG. 7C, when the original K is further fed in the sub-scanning direction by 125 μm and the third reading operation is performed, as shown in FIG. For the third line L3 of the document K, an image signal for red light is provided by the light receiving element 1R, for the fourth line L4, an image signal for green light is provided by the light receiving element 1G, and for the fifth line L5, a light receiving element is provided. 1B provides an image signal for blue light.

According to the third reading operation, for the third line L3 on the document K, all three color light components of red light, green light and blue light are received by the three types of light receiving elements 1R and 1R.
The light is received by G and 1B, and an effective signal is obtained as an image signal of a color image. Therefore, all reading operations after the third reading operation are valid. More specifically, in the fourth reading operation shown in FIG. 4D, the red light green light, the fourth line L4,
And image signals for all of the blue light are obtained. Thereafter, when the original K is read in the same manner while feeding the original K in the sub-scanning direction, the red light, green Image signals for all of the light and the blue light are obtained.

As described above, in this embodiment,
Since the three types of light sources R, G, and B are simultaneously turned on to read three lines at a time and to read different colors for each reading line, image data of each color is read. Can be obtained in parallel. The image data read in parallel is converted into an analog signal and output from the image sensor chip 5 in parallel for each color as described above.
That is, as in the case where the three types of light sources R, G, and B are switched to read image data for each color, and these data are output serially, the color output due to the previously output data remains. The occurrence of mixing is avoided.

In the above embodiment, the reading is actually performed three times for each line. However, the reading of the image data of each color is performed in parallel using three lines as a basic unit. As a result, it is the same as the case where image data of each color is read simultaneously for each line in an image reading apparatus configured to read an image line by line. For this reason,
In the image reading apparatus A having the above-described configuration, image reading is theoretically performed at about three times the speed as compared with the case where three types of light sources R, G, and B are sequentially switched for each line to perform image reading three times. And speeding up image reading can be realized. Of course, when performing the reading operation each time, at least one of the three types of light sources R, G, and B is not turned on / off each time.
It is preferable that the light is continuously turned on until reading of the original is completed. When the three types of light sources R, G, and B are always turned on, the light sources R, G, and B
The time required to switch between turning on and off can be reduced, and this also makes it possible to realize high-speed image reading.

As described above, a white LED may be used as the light source. In this case as well, if the reading operation described in the above embodiment is performed, the speed of image reading can be similarly increased. And the reproducibility of the read image can be improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view illustrating an example of an image reading apparatus according to the present invention.

FIG. 2 is an assembled sectional view of the image reading device.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a plan view of a chip-shaped substrate on which an image sensor chip and three types of light sources mounted on the image reading device are mounted.

FIG. 5 is a main part plan view showing an arrangement of a plurality of light receiving elements.

FIG. 6 is a circuit block diagram illustrating an example of a circuit configuration of an image sensor chip.

FIG. 7 is a circuit block diagram illustrating an example of an output adjusting unit that adjusts an output level of a signal output from the image sensor chip.

FIGS. 8A to 8D are explanatory diagrams showing a reading operation state of a document image using the image reading device; FIGS.
(E)-(h) is an explanatory view showing a state of an image signal obtained by these reading operations.

FIG. 9 is a graph showing a relationship between a dynamic range (output voltage) and a charge remaining rate in a phototransistor.

[Explanation of symbols]

Reference Signs List A Image reading device K Document R Red light source G Green light source B Blue light source VR1 to VR6 Variable resistance (as output level adjusting means) 1R Light receiving element for red 1G Light receiving element for green 1B Light receiving element for blue 5 Image sensor chip

Claims (6)

[Claims] 1. An image reading apparatus comprising three types of light sources for emitting red, green, and blue light, respectively, wherein the red light outputs a signal corresponding to the amount of received light of each color of red, green, and blue. , Green, and blue light-receiving elements, and illuminate the original with white light by simultaneously or substantially simultaneously turning on the three light sources. Of the light reflected from the original, An image reading apparatus, wherein each of the light receiving elements receives light of a color which is assigned to it. 2. A white LED is used as a light source, receives light emitted from the light source and reflected from a desired original, and according to the amount of received light of red, green, and blue of the reflected light. An image reading apparatus comprising a plurality of three types of light receiving elements for red, green and blue for outputting signals. 3. The image reading device according to claim 1, wherein the plurality of light receiving elements are arranged in the main scanning direction with respect to the plurality of light receiving elements of the same type, and the light receiving elements of different types are respectively sub-scanned. An image reading device, wherein the image reading device is arranged in a direction. 4. The image reading apparatus according to claim 3, further comprising output level adjusting means for equalizing output levels of signals output from the three types of light receiving elements. 5. Each of the color light sources or the white LEDs is
5. The image reading device according to claim 3, wherein the image reading device is configured to read the image data of each color in parallel while continuously or substantially continuously lighting the image of the original. 6. A basic unit is composed of three lines in the sub-scanning direction of a document, and the basic unit is irradiated with white light to read different colors for each line, and the reading operation is shifted by one line. 6. The image reading apparatus according to claim 5, wherein the image reading apparatus is configured to sequentially perform reading until one document is read.