JPH1188599A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader in which duplicate reading in the subscanning direction is avoided. SOLUTION: The image reader is provided with a read control means where for each period when a photoelectric conversion element array for each color is moved by a distance P relatively in the subscanning direction, while a period when a photoelectric conversion element array for each color is moved by a distance P-L or below relatively in the subscanning direction, the electric charge stored in the photoelectric conversion element for each color is acquired as a regular read image signal and the electric charge stored in the photoelectric conversion element for each color for other periods is disregarded as a useless read image signal, which are realized by a CPU 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which a large number of photoelectric conversion elements for receiving red, green, and blue light through a color filter are arranged in a row at a predetermined pitch in the main scanning direction. A substrate in which a plurality of color line image sensor chips are arranged in a row in the main scanning direction and arranged so that the photoelectric conversion element rows are arranged in parallel in the sub-scanning direction at a predetermined pitch. The present invention relates to an image reading apparatus that relatively and continuously moves a color line image sensor chip and an object to be read in a sub-scanning direction.

[0002]

2. Description of the Related Art As an image reading apparatus, a large number of photoelectric conversion elements for receiving red, green, and blue light through color filters are arranged in a line at a predetermined pitch in the main scanning direction. In addition, there is a type that employs a color line image sensor chip in which the photoelectric conversion element rows are arranged in parallel in the sub-scanning direction at the same predetermined pitch as the main scanning direction.

In such a conventional image reading apparatus, an original is moved in a direction opposite to the sub-scanning direction by a distance equal to the arrangement pitch of the photoelectric conversion element rows in the sub-scanning direction during reading of one line of each color. It was configured to be transported. That is, when the document is transported in the direction opposite to the sub-scanning direction, the same result as when the photoelectric conversion element array is moved in the sub-scanning direction is obtained.

However, in the conventional image reading apparatus as described above, as shown in FIG. 7, for example, the length of the light receiving surface of the photoelectric conversion element 31 in the sub-scanning direction is L, and
If the arrangement pitch in the sub-scanning direction is P, the photoelectric conversion element 31 moves by P in the sub-scanning direction during the reading period T of one line, so that an image having a length of P + L in the sub-scanning direction is read. Then, since reading is repeated for each pixel by the length of L, the color information of the original image cannot be read accurately.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been conceived under the circumstances described above, and has as its object to provide an image reading apparatus capable of eliminating redundant reading in the sub-scanning direction. .

In order to solve the above problems, the present invention takes the following technical measures.

According to the first aspect of the present invention, a large number of photoelectric conversion elements that receive red, green, and blue light through a color filter are arranged at a predetermined pitch in the main scanning direction. A substrate having a plurality of color line image sensor chips arranged in a row in the main scanning direction, and arranged in such a manner that the photoelectric conversion element rows are arranged in parallel with each other at a predetermined pitch in the sub-scanning direction, During the reading period, the color line image sensor chip and the object to be read are relatively and continuously moved in the sub-scanning direction, and the white light source that irradiates the object to be read is always turned on. An image reading apparatus for constantly outputting read image signals simultaneously from a row, wherein an arrangement pitch in the sub-scanning direction of a photoelectric conversion element row for each color is P, and a sub-scanning direction of a light receiving surface of the photoelectric conversion element for each color is P. When the length is set to L, the charge accumulation of the read image of one line of each color is performed while the photoelectric conversion element array for each color moves relatively less than PL in the sub-scanning direction. Output timing control means for controlling the output timing of the read image signal from the photoelectric conversion element for each color, and for each period during which the photoelectric conversion element row for each color relatively moves the distance of P in the sub-scanning direction, The charge accumulated in the photoelectric conversion element for each color is acquired as a normal read image signal while the photoelectric conversion element row for each color moves relatively less than P-L in the sub-scanning direction. And a reading control unit for ignoring charges accumulated in the photoelectric conversion elements for each color as useless read image signals.

With this arrangement, the reading control means sets the photoelectric conversion element array for each color in the sub-scanning direction every time the photoelectric conversion element array for each color moves the distance P relatively in the sub-scanning direction. The electric charge accumulated in the photoelectric conversion element for each color is acquired as a normal read image signal while moving a distance less than P-L relative to the above, and the electric charge accumulated in the photoelectric conversion element for each color in other periods. Since the charge is ignored as an unnecessary read image signal, redundant reading in the sub-scanning direction can be eliminated, so that the color information of the original image can be read accurately.

That is, the effective reading period of one line is defined as a period during which the photoelectric conversion element array for each color moves a distance of P-L or less in the sub-scanning direction. Is less than or equal to P, and redundant reading can be eliminated.

The period during which the readout image signal for one line is output once from the photoelectric conversion element for each color is the period during which the photoelectric conversion element row for each color moves a distance P relatively in the sub-scanning direction. It is necessary to set so that it becomes 1 / integer.

Although a phototransistor can be used as the photoelectric conversion element, the invention is not limited to this, and a photodiode or the like may be used.

As the white light source, a cold cathode tube can be used. However, the present invention is not limited to this. For example, red, green, and blue light emitting diodes may be simultaneously turned on.

The output timing control means and the read control means can be realized by a CPU which operates based on a predetermined program, but is not limited thereto, and may be realized by a gate array or a PLA (programmable logic array).

According to a preferred embodiment, the reading control means sets the photoelectric conversion element array for each color in the sub-scanning direction each time the photoelectric conversion element array for each color moves relatively P distance in the sub-scanning direction. The electric charge accumulated in the photoelectric conversion element for each color is acquired as a regular read image signal while moving in the scanning direction a distance slightly smaller than P-L, and the photoelectric conversion element for each color is acquired in other periods. Are ignored as unnecessary read image signals.

With this arrangement, the length of the reading area in the sub-scanning direction is slightly smaller than P, and even if the relative scanning speed in the sub-scanning direction slightly fluctuates, overlapping reading is performed. Can be reliably eliminated.

According to the second aspect of the present invention, a large number of photoelectric conversion elements that receive red, green, and blue light through a color filter are arranged at predetermined pitches in the main scanning direction. A substrate having a plurality of color line image sensor chips arranged in a row in the main scanning direction, and arranged in such a manner that the photoelectric conversion element rows are arranged in parallel with each other at a predetermined pitch in the sub-scanning direction, An image reading apparatus for moving a color line image sensor chip and a reading object relatively and continuously in a sub-scanning direction during a reading period, wherein the arrangement pitch of photoelectric conversion element rows for each color in the sub-scanning direction is P. When the length of the light receiving surface of the photoelectric conversion element for each color in the sub-scanning direction is L, each period in which the photoelectric conversion element row for each color moves a distance P relatively in the sub-scanning direction, Photoelectric conversion element for each color Light source control means for turning on the white light source for illuminating the object to be read during a period in which the column relatively moves in the sub-scanning direction by a distance of P-L or less, and turning off the white light source during other periods; And a reading control unit for outputting a one-line read image signal from the photoelectric conversion element for each color while the white light source is turned off.

According to this structure, the light source control means sets the photoelectric conversion element array for each color in the sub-scanning direction in each period in which the photoelectric conversion element array for each color relatively moves the distance P in the sub-scanning direction. Since the white light source for illuminating the object to be read is turned on during the period of moving relatively less than P-L, and the white light source is turned off during the other periods, it is possible to eliminate redundant reading in the sub-scanning direction. Therefore, the color information of the original image can be accurately read.

That is, a period during which the photoelectric conversion element array for each color moves relatively less than P-L in the sub-scanning direction is an effective reading period for one line. Is less than or equal to P, and redundant reading can be eliminated.

As the white light source, a white light emitting diode can be used.
Green and blue light emitting diodes may be turned on simultaneously.

The light source control means and the read control means can be realized by a CPU which operates based on a predetermined program.
It may be realized by an LA (programmable logic array) or the like.

According to the preferred embodiment, the light source control means sets the photoelectric conversion element array for each color in the sub-scanning direction every time the photoelectric conversion element array for each color moves the distance of P relatively in the sub-scanning direction. The white light source for illuminating the object to be read is turned on during a period of moving a distance slightly smaller than P-L in the scanning direction, and the white light source is turned off during other periods.

Even if the length of the reading area in the sub-scanning direction is slightly smaller than P, and even if the relative scanning speed in the sub-scanning direction has a slight unevenness, it is possible to surely eliminate redundant reading. it can.

According to another preferred embodiment, the length L of the light receiving surface of the photoelectric conversion element for each color in the sub-scanning direction is 1/1 / the pitch P of the photoelectric conversion element row for each color in the sub-scanning direction.
2.

According to this configuration, the period during which the read image signal output from the photoelectric conversion element is acquired and the period during which the read image signal is ignored can be made the same, or the lighting period and the light-off period of the white light source can be made the same. Can be easily performed.

[0025] Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

[0026]

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

FIG. 2 is a cross-sectional view in a direction perpendicular to the longitudinal direction of the contact type color line image sensor provided in the image reading apparatus according to the present invention. The color line image sensor 1 has a substantially rectangular shape. And a case 2 having a predetermined longitudinal dimension, and the case 2 can be manufactured by resin molding. The case 2 has an internal space that penetrates vertically and has a glass cover 3 attached so as to close an upper opening and a head substrate 4 attached so as to seal a lower opening. A plurality of color line image sensor chips 5 are mounted on one side of the upper surface of the head substrate 4 in the width direction. A cold cathode tube 7 as a white light source is provided in the internal space of the case 2.
A reflecting member 8 for efficiently irradiating the light emitted from the cold cathode tube 7 to the original as the object to be read on the glass cover 3, and a color line image of the reflected light from the original surface being erected at equal magnification. A rod lens array 9 for focusing on the sensor chip 5 is provided. In the right place of Case 2,
An inverter board 10 on which an inverter circuit for driving the cold cathode tubes 7 is mounted is fitted. In the case 2, a pair of mounting holes 11a and 11b having a circular cross section are formed along the longitudinal direction.

FIG. 3 is a plan view of the head substrate 4.
On the head substrate 4, twenty color line image sensor chips 5 are mounted along the long side of the head substrate 4, that is, in a line in the main scanning direction. A connector 12 for supplying power to the color line image sensor chip 5 and inputting / outputting various signals is provided on the head substrate 4.
Is attached.

FIG. 4 is a circuit block diagram of a control unit of the image reading apparatus according to the present invention.
15, an ROM 16, a RAM 17, and an input / output interface 18. Input / output interface 1
8, the head substrate 4, the inverter substrate 10, and the motor 19 are connected.

The CPU 15 controls the entire image reading device. The ROM 16 stores a program for operating the CPU 15 and the like. The RAM 17 is a CPU 1
5, a work area is supplied, and various data are stored.
The input / output interface 18 controls input / output of signals between the CPU 15 and the head substrate 4, the inverter substrate 10, and the motor 19, and converts an analog read image signal into a digital read image signal. Motor 1
Reference numeral 9 drives a plurality of transport rollers for transporting the document in a direction opposite to the sub-scanning direction.

FIG. 1 is a plan view of a main part of a color line image sensor chip 5, which has a large number of red color filters covered with a color filter that transmits red light. Photoelectric conversion element 21
_R , a large number of photoelectric conversion elements 21 _G for green covered with a color filter that transmits green light, and a large number of photoelectric conversion elements 21 _B for blue covered with a color filter that transmits blue light. Along the long side of the color line image sensor chip 5 at a predetermined pitch P,
That is, they are arranged in a line in the main scanning direction. The photoelectric conversion elements 21 _R , 21 _G , and 21 _B for each color are
Along the short side of the color line image sensor chip 5,
That is, they are arranged at the same pitch P in the sub-scanning direction as in the main scanning direction. Then, the photoelectric conversion elements 21 _R , 2 for each color
The length L of the light receiving surfaces of 1 _G and 21 _B in the sub-scanning direction is の of the pitch P.

FIG. 5 is a circuit block diagram of the color line image sensor chip 5. The color line image sensor chip 5 includes a 128-bit shift register 22, a chip select circuit 23, and 128 red photo sensors. Transistors PTR _{1 to} PTR ₁₂₈ , 128 green phototransistors PTG _{1 to} PTG ₁₂₈ , 128
Number of phototransistors PTB ₁ ~PTB ₁₂₈ for blue,
128 first field effect transistors FET for red
R ₁ ～FETR _128, 128 of the first field effect transistor FETG ₁ ～FETG ₁₂₈ for green, 128 of the first field effect transistor FETB ₁ ～FE for blue
TB ₁₂₈ , red second field effect transistor FET
R ₂₀₁ , green second field effect transistor FETG
₂₀₁ , second field effect transistor FETB for blue
₂₀₁ , third field effect transistor FETR for red
₂₁₁ , third field effect transistor FETG for green
₂₁₁ , third field effect transistor FETB for blue
₂₁₁ , an operational amplifier OPR ₁ for red, an operational amplifier OPG ₁ for green, an operational amplifier OPB ₁ for blue, and three for red
Resistors RR _{1 to} RR ₃ , three resistors RG for green
_{1 ~RG 3, 3} pieces of resistors RB ₁ ~RB ₃ for blue, and 11 of the pad SI, CLK, GND, AOR1,
AOR2, SO, AOG1, AOG2, AOB1, AO
B2 and VDD are formed. First field effect transistors FETR _{1 to} FETR ₁₂₈ , FETG _{1 to} FET
G _128, FETB ₁ ~FETB _128, a second field effect transistor FETR _201, FETG _201, FET
B ₂₀₁ , and a third field effect transistor FETR
₂₁₁ , FETG ₂₁₁ and FETB ₂₁₁ are MOS type field effect transistors.

The pad SI receives a serial-in signal. For example, 8M is supplied to the pad CLK from outside the color line image sensor 1 through the connector 12 or the like.
Hz clock signal is input. The pad GND is connected to a ground line. From the pad AOR1, an analog red read image signal that has not been amplified is serially output. An amplified analog red read image signal is serially output from the pad AOR2. From the pad AOG1, an analog green read image signal that has not been amplified is serially output. Pad A
From OG2, the amplified analog green read image signal is output serially. From the pad AOB1, an analog blue read image signal that has not been amplified is serially output. From the pad AOB2, the amplified analog blue read image signal is serially output. The pad SO outputs a serial out signal. A power supply voltage of, for example, 5 volts is supplied to the pad VDD from outside the color line image sensor 1 via the connector 12 or the like. Phototransistor PTR ₁ ~PTR
₁₂₈ constitute a photoelectric conversion element 21 _R. Phototransistor PTG ₁ ~PTG ₁₂₈ includes a photoelectric conversion element 21 _G
Is composed. Phototransistor PTB ₁ ~PTB
₁₂₈ constitute a photoelectric conversion element 21 _B.

Next, the operation will be described. When reading
Is an inverter circuit of the inverter board 10 by the CPU 1.
The path is controlled so that the cold-cathode tube 7 is turned on and the CPU
1, the motor 19 is controlled, and the original is
Is transported on the glass cover 3 in the direction opposite to the sub-scanning direction.
You. As a result, the surface of the original radiated from the cold cathode fluorescent lamp 7
Reflected by the photoelectric conversion element 21_R, 21_G, 21
_BOf the photoelectric conversion element 21_R, 21_G, 2
1_BIs converted into an electric signal. At this time, photoelectric conversion
Element 21_R, 21_G, 21_BIs controlled by the CPU 1.
The document is moved a distance P-L in the direction opposite to the sub-scanning direction.
Output one read image signal for one line during operation
You. Then, while moving the distance L further, one line
The read image signal is output once every minute. CPU1 is a manuscript
Moves a distance P-L in the direction opposite to the sub-scanning direction.
Photoelectric conversion element 21_R, 21_G, 21_BCharge stored in
Read image signal based on the image is adopted as a legitimate read image signal
Then, processing such as storing in the RAM 17 is performed.
Photoelectric conversion element 21 while moving the distance L_R, 2
1 _G, 21_BImage signal based on electric charge accumulated in
Are ignored as unnecessary read image signals. This implementation
In the embodiment, L = P / 2, and P−L = P / 2.
Therefore, the original is moved in the direction opposite to the sub-scanning direction by P, ie, 1
While moving the distance of the pixel, the photoelectric conversion element 21_R, 2
1_G, 21_BOutputs one line of read image signal twice
And the first one of them
Validates the read image signal and the second read image for one line
The image signal is invalidated. Of course, the first one la
Invalidates the read image signal for IN and the second time for one line
May be valid.

Here, the original is placed in a direction opposite to the sub-scanning direction.
-L, the photoelectric conversion elements 21 _R , 2
The length of the reading area in the sub-scanning direction due to 1 _G and 21 _B is P, that is, one pixel, and by overlapping the first-time read image signal for one line during this period, overlapping in the sub-scanning direction is possible. The image can be read without the need.

That is, as shown in FIG. 6, the red read image signal R obtained in the first half T / 2 of the period T during which the original moves P, ie, the distance of one pixel, in the direction opposite to the sub-scanning direction. _n , R _{n + 1} , R _{n + 2} , R _{n + 3} , ─, green read image signals G _n−1 , G _n , G _{n + 1} , G _{n + 2} , ─, and blue read image signal B _n-2 , _Bn-1 , _Bn , _{Bn + 1} ,... are processed as effective read image signals for each line of each color,
Red read image signals R _n ′, R obtained in the latter half T / 2
_{n + 1} ', Rn _{+ 2} ', Rn _{+ 3} ', ─, green read image signals _Gn-1 ', _Gn ', _{Gn + 1} ', _{Gn + 2} ', お よ び, and blue Read image signals B _n-2 ', B _n-1 ', B _n ',
By ignoring B _{n + 1} ′, 無効 as invalid read image signals for each line of each color, there is no overlap for each period T during which the document moves in the direction opposite to the sub-scanning direction, that is, the distance of one pixel. One line of image can be read.

Of course, the photoelectric conversion elements 21 _R , 2 of each color
1 _G and 21 _B are sequentially arranged at a distance of P in the sub-scanning direction, that is, one pixel, and read image signals of each color obtained at the same time are, for example, R _n , G _n-1 , and B _n-2. As described above, since the lines are shifted by one line, the CPU 1 rearranges the combination into a correct combination for each pixel.

Next, the operation of the color line image sensor chip 5 will be described in detail. When reading is started, a serial-in signal is supplied from the CPU 1 to the pad SI of the first-stage color line image sensor chip 5 of the 20 color line image sensor chips 5 via the input / output interface 18 and the connector 12. You. This serial-in signal is output to the chip select circuit 2
3, the chip select circuit 23 sets the select signal output from the select signal output terminal to a high level in synchronization with the clock signal CLK. The select signal is a signal obtained by inverting the clock signal CLK, and includes second field effect transistors FETR ₂₀₁ , FETG ₂₀₁ , and FE for each of red, green, and blue colors.
Since the clock is supplied to the gate of the TB ₂₀₁ , each second field-effect transistor F
The ETR ₂₀₁ , the FET G ₂₀₁ and the FET B ₂₀₁ are turned on.

The serial-in signal SI is also supplied to the input terminal of the shift register 22, and is taken into the first-stage bit of the shift register 22 at the falling edge of the clock signal. As a result, the first-stage bit of the shift register 22 is turned on, and a high-level signal is input to the gates of the first field-effect transistors FETR ₁ , FETG ₁ , and FETB ₁ for each of red, green, and blue. Field effect transistors FETR ₁ , FETG ₁ , FETB ₁
Turns on. At this time, since the clock signal is at a low level, the third field effect transistors FETR ₂₁₁ , FETG ₂₁₁ , and FETB ₂₁₁ for red, green, and blue are off, and the phototransistors for red, green, and blue are off. PT
The currents due to the electric charges accumulated in R ₁ , PTG ₁ , and PTB ₁ are respectively changed by the first field-effect transistors FETR ₁ , FETG
₁ , a resistor RR for each color of red, green and blue via FETB _1
3 , RG ₃ and RB ₃ . These resistors RR ₃ , R
The voltages at both ends of G ₃ and RB ₃ are inputted to the non-inverting input terminals of operational amplifiers OPR ₁ , OPG ₁ and OPB ₁ for red, green and blue, respectively, and the resistors RR ₁ , RG ₁ and RB ₁ and the resistors R
Pads AOR2 for each of red, green, and blue are amplified at an amplification determined by the ratio of the resistance value to R ₂ , RG ₂ , and RB ₂ .
AOG2 and AOB2 output analog read image signals. At this time, the clock signal is at a low level, since the select signal is at the high level, the second field effect transistor FETR _201, FETG _{20 1,} FE
TB ₂₀₁ is on. Note that analog read image signals not amplified by the operational amplifiers OPR ₁ , OPG ₁ , OPB ₁ are output from the pads AOR 1, AOG 1, AOB ₁ for red, green, and blue, respectively.

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.

When the clock signal falls from the high level to the low level, the serial-in signal SI of the first bit of the shift register 21 is shifted to the second bit,
By the same operation as that of the first stage bit, phototransistors PTR ₂ , PTG ₂ , and PTB ₂ for red, green, and blue colors
Analog read image signals corresponding to the charges stored in the pads AOR2, AOG2, AOB for the red, green, and blue colors
2 output.

Hereinafter, the phototransistors PTR ₃ to PTR ₃ for red, green, and blue are synchronized in synchronization with the clock signal by the same operation.
_{PTR 128, PTG 3 ~PTG 128,} PTB 3 ~PTB
Analog read image signals corresponding to the electric charges accumulated in ₁₂₈ are pads AOR2, AOG2, and AO for red, green, and blue, respectively.
When sequentially output from B2, a serial-in signal is output from the last bit of the shift register 22 at the falling edge of the next clock signal CLK, and the chip select circuit 23
Is input as a clear signal to the clear signal input terminal and is output from the pad SO as a serial out signal. As a result, the chip select circuit 23 keeps the select signal at low level. The serial out signal output from the pad SO is input to the pad SI of the color line image sensor chip 5 at the next stage as a serial in signal.

As a result, the next-stage color line image sensor chip 5 operates in the same manner as the first-stage color line image sensor chip 5, and synchronizes with the clock signal to generate red,
Phototransistors PTR _{1 to} PT for green and blue colors
_{R 128, PTG 1 ~PTG 128,} PTB 1 ~PTB 128
Analog read image signals corresponding to the charges stored in the pads AOR2, AOG2, AOB for the red, green, and blue colors
2 are sequentially output. By repeating such an operation up to the final stage, that is, the twentieth color line image sensor chip 5, 2560 pixels from the twenty color line image sensor chips 5, that is, read image signals of each color of one line are input / output. Interface 18
Is converted into a digital read image signal and stored in the RAM 17. During this time, the original is conveyed by a distance of P-L in a direction opposite to the sub-scanning direction. Since the read image signals of each color are output at the same time, the input / output interface 18 sequentially selects the read image signals of red, green, and blue in a time division manner by a multiplexer or the like. Of course, phototransistors PTR _{1 to} PTR for each color
TR ₁₂₈ , PTG _{1 to} PTG ₁₂₈ , PTB _{1 to} PTB
_{The 128} charge accumulation periods are all periods other than the period selected by the shift register 22.

Similarly, the read image signals of red, green, and blue for one line are continuously output to the input / output interface 18.
Is supplied to the input / output interface 18
Captures them once every two times.

In the above embodiment, light for each color is used.
Electric conversion element 21_R, 21_G, 21_BSub-scanning method of the light receiving surface
The length L in the direction is set to the photoelectric conversion element 21 for each color._R, 21_G,
21 _B配置 of the arrangement pitch P in the sub-scanning direction,
It is not necessary to do so.

In the above embodiment, the light for each color is used.
Electric conversion element 21_R, 21_G, 21_BIs relative to the sub-scanning direction
Photoelectric conversion element for each color while moving a distance of PL
21 _R, 21_G, 21_BImage signal for one line from
Is output, but this is not necessarily the case.
It is not necessary to form the photoelectric conversion element 2 for each color.
1_R, 21_G, 21_BIs relatively P-L in the sub-scanning direction.
Photoelectric conversion element for each color while traveling a slightly smaller distance
Child 21_R, 21_G, 21_BImage data for one line from
Signal may be output.

In this manner, the length of the one-line reading area in the sub-scanning direction is slightly smaller than P, that is, the length of one pixel. This makes it possible to obtain a reproduced image that is superior to performing overlapped reading without performing repeated reading.

In the above embodiment, the CPU 15
Although the control elements such as are provided outside the color line image sensor 1, they may be provided inside the color line image sensor 1. In this case, a control element such as the CPU 15 may be mounted on the head substrate 4 or may be mounted on a substrate different from the head substrate 4.

In the above embodiment, the cold cathode fluorescent lamp 7 is used as a white light source, and the photoelectric conversion elements 21 _R , 21 _G ,
While constantly charge the 21 _B is configured to be accumulated, the light emitting diode is used as a white light source, the sub-scanning direction arrangement pitch of the photoelectric conversion element array for each color is P, the light-receiving surface of the photoelectric conversion elements for each color When the length in the sub-scanning direction is L, the photoelectric conversion element array for each color is relatively P in the sub-scanning direction.
The white light source for illuminating the object to be read is turned on during a period in which the photoelectric conversion element array for each color moves a distance of P-L or less relatively in the sub-scanning direction for each period of moving the distance. During the period, the white light source may be turned off, and while the white light source is turned off by the light source control unit, one line of the read image signal may be output from the photoelectric conversion element for each color.

Also in this case, the length of the reading area in the sub-scanning direction can be P or less. That is, by turning on the white light source that irradiates the object to be read only during the period in which the photoelectric conversion element row for each color moves relatively less than P-L in the sub-scanning direction, the photoelectric conversion element for each color is turned on. Of the photoelectric conversion element row for each color in the sub-scanning direction.
Since the distance of -L or less can be limited to the moving period, the length of the reading area in the sub-scanning direction can be P or less.

Of course, the light source control means causes the photoelectric conversion element array for each color to move relative to the sub-scanning direction during each period in which the photoelectric conversion element array for each color moves a distance P relatively in the sub-scanning direction. The white light source that irradiates the object to be read may be turned on during a period of moving a distance slightly smaller than PL, and the white light source may be turned off during other periods.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of a color line image sensor chip provided in an image reading apparatus according to the present invention.

FIG. 2 is a cross-sectional view in a direction orthogonal to a longitudinal direction of a color line image sensor provided in the image reading apparatus according to the present invention.

FIG. 3 is a plan view of a head substrate provided in the color line image sensor shown in FIG. 2;

FIG. 4 is a circuit block diagram of a control unit of the image reading apparatus according to the present invention.

FIG. 5 is a circuit diagram of a color line image sensor chip provided in the color line image sensor shown in FIG. 2;

6 is an explanatory diagram of output timings of read image signals of each color by a color line image sensor chip provided in the color line image sensor shown in FIG. 2;

FIG. 7 is an explanatory diagram of a reading area by a conventional image reading apparatus.

[Explanation of symbols]

1 color line image sensor 4 head substrate 5 color line image sensor chip 7 cold cathode tubes 15 CPU 16 ROM 17 RAM 18 output interface 19 motor 21 _R, 21 _G, 21 _B photoelectric conversion element

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Norihiro Imamura Inventor No. 21 Saizou Mizozakicho, Ukyo-ku, Kyoto-shi ROHM Co., Ltd.

Claims (5)

[Claims] 1. A large number of photoelectric conversion elements that receive red, green, and blue light via a color filter are arranged in a row at a predetermined pitch in the main scanning direction. A substrate having a plurality of color line image sensor chips arranged in a row in the main scanning direction, the element lines being arranged so as to be arranged in parallel with each other at a predetermined pitch in the sub-scanning direction; The chip and the object to be read are relatively and continuously moved in the sub-scanning direction, and the white light source that irradiates the object to be read is always turned on. Furthermore, the read image signal is simultaneously read from the photoelectric conversion element array for each color. An image reading apparatus that constantly outputs, wherein P is an arrangement pitch of the photoelectric conversion element array for each color in the sub-scanning direction, and L is a length of the light receiving surface of the photoelectric conversion element for each color in the sub-scanning direction. When the photoelectric conversion element row for each color moves a distance of P-L or less relatively in the sub-scanning direction, the charge accumulation of the read image for one line of each color is performed. Output timing control means for controlling the output timing of the read image signal from the photoelectric conversion element for each color, and for each period during which the photoelectric conversion element row for each color moves a distance P relatively in the sub-scanning direction, While the photoelectric conversion element row for each color moves relatively less than P-L in the sub-scanning direction, the electric charge accumulated in the photoelectric conversion element for each color is obtained as a normal read image signal, and other An image reading device, comprising: reading control means for ignoring charges accumulated in the photoelectric conversion elements for the respective colors during a period as unnecessary read image signals. 2. The reading control unit according to claim 1, wherein the photoelectric conversion element array for each color is moved in the sub-scanning direction every time the photoelectric conversion element array for each color moves a distance of P relatively in the sub-scanning direction. The electric charge accumulated in the photoelectric conversion element for each color is obtained as a regular read image signal while moving a distance slightly smaller than P-L, and the photoelectric conversion element for each color is acquired in other periods. 2. The image reading apparatus according to claim 1, wherein the stored charges are ignored as unnecessary read image signals. 3. A large number of photoelectric conversion elements that receive red, green, and blue light via a color filter are arranged in a row at a predetermined pitch in the main scanning direction. A substrate having a plurality of color line image sensor chips arranged in a row in the main scanning direction, the element lines being arranged so as to be arranged in parallel with each other at a predetermined pitch in the sub-scanning direction; What is claimed is: 1. An image reading apparatus for moving a chip and an object to be read relatively and continuously in a sub-scanning direction, wherein an arrangement pitch in a sub-scanning direction of a photoelectric conversion element array for each color is P, Assuming that the length of the light receiving surface of the conversion element in the sub-scanning direction is L, the photoelectric conversion element array for each color moves every P distance in the sub-scanning direction relatively. Conversion element row A light source control unit that turns on a white light source that irradiates the object to be read during a period of moving relatively less than P-L in the scanning direction, and turns off the white light source during other periods; An image reading device comprising: a reading control unit that outputs a read image signal for one line from the photoelectric conversion element for each color while the white light source is turned off. 4. The light source control means, wherein the photoelectric conversion element array for each color is moved in the sub-scanning direction every time the photoelectric conversion element array for each color moves a distance P relatively in the sub-scanning direction. The image reading apparatus according to claim 3, wherein a white light source that irradiates the object to be read is turned on during a period of moving a distance slightly smaller than P−L, and the white light source is turned off in other periods. . 5. The length L of the light-receiving surface of the photoelectric conversion element for each color in the sub-scanning direction is の of the arrangement pitch P of the photoelectric conversion element row for each color in the sub-scanning direction. The image reading device according to claim 1.