JPH06205172A - Picture input device - Google Patents

Abstract

PURPOSE:To allow the device to read picture information with excellent picture quality with excellent stability of the subscanning speed. CONSTITUTION:The device is provided with a displacing means (piezoelectric actuator) 4 using a carrier system 3 to continuously carry a read section (CCD line sensor) 2 with photoelectric conversion elements arranged therewith in the main scanning direction toward the subscanning direction perpendicular to the main scanning direction and displacing the read section 2 in the subscanning direction or a direction opposite thereto independently of the subscanning drive by the carrier system 3. The dispersion in the moving speed caused at the time of carrying is cancelled by the means 4 through the movement of the read section 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input device.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for reading image information from a two-dimensional image recorded matter such as an original document or a photograph such as an image scanner, a line sensor is arranged in the main scanning direction and the line sensor is used as an original document. There is used a mechanism for reading image information by moving it relative to the sub-scanning direction.

The positions where the main scanning is performed by such a line sensor are provided at every one sensor pitch (7 to 14 μm), and the intervals are extremely minute intervals. Therefore,
If the sub-scanning speed is slightly disturbed, there arises a problem that a high-definition image cannot be obtained. In particular, when reading a high-definition color image, a 3-line type CCD sensor provided with three sensor lines for reading red (R), green (G), and blue (B) separately is used. Therefore, even if a slight change occurs in the sub-scanning speed, the above-mentioned respective colors do not overlap with each other and color bleeding occurs, which causes more problems.

As described above, keeping the sub-scanning speed constant with high accuracy is an important mechanical condition in an image input device for performing main scanning and sub-scanning, and in particular, a high-definition color image is input. In this case, it is necessary to control the sub-scanning speed with extremely high accuracy. By the way, as a conventional mechanism for sub-scanning drive, a mechanism including a lead screw and a carriage having a nut screwed to the lead screw is used. Further, this lead screw has a drunkenness of lead, which is reflected by a processing error of the processing machine, and an error due to a scratch in a screw groove.

Of these, the random walk error is a lead error in which the advance of the thread groove within one lead of the lead screw increases or decreases with one lead pitch as one cycle, as shown in FIG. Then, due to the random walk error, even if the lead screw is rotated at a constant speed, a change in the carriage moving speed corresponding to the random walk error occurs.

In order to prevent such a change in the moving speed and maintain the sub-scanning speed constant with high accuracy, it is necessary to use a lead screw with high processing accuracy with a small random walk error. The manufacturing cost for obtaining the lead screw is high. Further, there is a limit to improvement of processing accuracy, and it is impossible to control the moving speed with sufficient accuracy. Further, it is not possible to deal with variations in the moving speed of the carriage due to causes other than the lead error of the lead screw. On the other hand, with the development of multimedia creation devices such as image databases, images of small-sized originals such as 35 mm film used in silver halide cameras (for example, 24.0 mm long × 36.0 mm wide) can be created. There is an increasing need for high-definition image input devices. In such an apparatus, it is necessary to control the sub-scanning speed with particularly high accuracy, and random walk errors and other mechanical errors make the control of the moving speed more difficult.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image input device which has good stability in the sub-scanning speed and which can read image information of good image quality.

[0008]

Such an object is achieved by the present invention described below. That is,

(1) A reading section which is provided so as to face the original and has a photoelectric conversion element for reading reflected light or transmitted light from the original arranged in the main scanning direction, and the reading section is orthogonal to the main scanning direction. A transport system that continuously moves in the sub-scanning direction and a displacement unit that displaces the reading unit in the sub-scanning direction or in a direction opposite to the sub-scanning direction, and the displacement unit scans by the transport system An image input device, wherein the reading unit is displaced so as to cancel the variation in the moving speed of the unit.

(2) Further, the control means has a control means for controlling the operation of the displacement means, and a memory for storing in advance information for correcting an error in the moving speed of the reading section by the transport system. The image input device according to (1) above, which controls the displacement means based on information from the memory.

(3) The image input device according to (1) or (2), which has a position detecting means for detecting the initial position of the reading section.

(4) The transport system includes a carriage on which the reading unit is mounted and which is movably supported in the sub-scanning direction, a nut provided on the carriage, a lead screw screwed to the nut, and the lead. The image according to any one of (1) to (3) above, further comprising a driving unit that drives a screw, and the variation in the moving speed is caused by a mechanical error of each component of the transport system. Input device.

(5) The image input device according to (4), wherein the mechanical error is mainly a lead screw lead error.

(6) The operation pattern of the displacement means is
The image input device according to (4) or (5), which is repeated in units of one rotation cycle of the lead screw.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is an internal perspective overall perspective view showing the structure of the image input apparatus 1 of the first embodiment.
As shown, the image input device 1 of the first embodiment.
Has a housing 1a and a document retainer 1b provided on the housing 1a so as to be openable and closable. The housing 1a has a reduction type CCD (Charge Coupler) as a reading unit therein.
d Device) Displacement of the CCD line sensor 2 in the sub-scanning direction or the opposite direction independently of the transport system 3 having the line sensor 2 and moving the CCD line sensor 2 and the drive by the transport system 3. Displacing means, and the C
The CD line sensor 2 has an urging means for urging the CD line sensor 2 in the direction in which the displacement means is located. The document P is placed on the housing 1a with the recording surface facing down.

As shown in FIG. 2, the CCD line sensor 2 has CCD chips 22 arranged in an array on a thick film ceramic substrate 21, and a condensing rod lens array 23 is installed above the CCD chips 22. A light emitting diode 24 is installed as a light source on the side of the condensing rod lens array 23 and is housed in a case 25. A window 251 is formed on the upper surface of the case 25, and the reflected light from the document P is CC through the window 251.
It is incident on D and charges are accumulated. The CCD line sensor 2 is electrically connected to a drive circuit 26 provided separately.

The CCD line sensor 2 can correspond to either a black and white image or a color image,
In the case of targeting a color image as in this embodiment, the CCD chip 22 is provided with each line for sensing each color of red, green and blue, and each line is provided with each line. Red, green and blue filters are covered respectively. When sub-scanning is performed by the CCD line sensor 2 as described above, the red, green, and blue sensing lines are sequentially moved to the same sub-scanning position, and the reading method and the sub-scanning are performed three times. There is a method to read each color. A plurality of sensing lines may be provided for each color.
In addition, with the increase in the number of sensing lines, a plurality of condensing rod lens arrays 23 may be provided. Here, the main scanning refers to scanning that the CCD line sensor 2 reads for each line.

Here, the CCD line sensor 2 of this embodiment
Has 5 pixels in the range of 36.0 mm in the main scanning direction.
143 pixels are arranged (7 μm pitch). The apparatus of this embodiment has sub-scanning positions corresponding to 3429 pixels in the range of 24.0 mm in the sub-scanning direction. With such a number of pixels, a high-definition image can be obtained. The pixel density used for obtaining a high-definition image by the device of the present invention can be about 19000 to 21000 pixels per square millimeter, or higher. The effect of the present invention is more effectively exhibited at a pixel density of this level.

On the other hand, the CCD line sensor 2 is moved in the sub scanning direction by the transport system 3. The transport system 3 includes a carriage 31 on which the CCD line sensor 2 is placed,
The rod-shaped guide members 32a and 32b for guiding the carriage 31 in the sub-scanning direction, the nut 33 provided on the carriage 31, the lead screw 34 screwed into the nut 33, and the lead screw 34 are provided. Bearings 35a and 35b for supporting the shaft and the lead screw 3
And a drive means for driving 4.

The driving means drives a driven gear 36 connected to one end of the lead screw 34, a drive gear 37 meshed with the driven gear 36, and a direct current (DC) for driving the drive gear 37. ) And a motor 38. The movable part that can be moved in the sub-scanning direction is
Carriage 31, nut 33, lead screw 3
4 and a driven gear 36.

As the nut 33, it is possible to use a ball screw having a steel ball in the valley portion of the internal screw. The guide members 32a and 32b are inserted into both ends of the carriage 31, and the carriage 31 moves in the sub-scanning direction while slidingly contacting the guide members 32a and 32b. Further, an encoder is built in the DC motor 38, and by the transmission pulse from the encoder,
The rotation speed is controlled so that the rotation speed of the DC motor 38 does not vary. The encoder is fixed to the drive shaft of the DC motor 38, and is composed of a disc having concentric circles with the drive shaft and having transmission holes formed at equal intervals in the circumferential direction, and a transmission type photo interrupter. .

Then, the disk rotates with the rotation of the DC motor 38, and every time the transmitted light of the photo interrupter passes through the transmission hole, the light reception and the light shielding are repeated in a cycle proportional to the rotation speed. Then, an output pulse having this cycle is transmitted from the encoder. DC motor 38
The drive gear 37 connected to the output shaft of the drive gear and the driven gear 36 meshing with the drive gear 37 are spur gears, and the meshing portions can slide even if the lead screw 34 is displaced in the axial direction. Is configured. The drive gear 37 has a sufficient width corresponding to the amount of displacement of the lead screw 34 so that the driven gear 36 does not come off even when the lead screw 34 is displaced in the axial direction. In the illustrated embodiment, the lead screw 34 rotates so that the carriage 31 moves (sub-scanning) from the end of the lead screw 34 where the driven gear 36 is provided to the other end.

On the other hand, the bearing 35 of the lead screw 34
The a and 35b pivotally support the lead screw 34 so as to be movable in the thrust direction. This lead screw 34
Is supported in parallel with the guide members 32a and 32b, and by the lead screw 34 and the nut 33,
When the lead screw 34 rotates, the carriage 31 moves in the sub scanning direction. The tip end 341 of the lead screw 34 is provided with the piezoelectric actuator 4 as a displacement means, and the base end 342 where the driven gear 36 is provided is provided with a leaf spring 5 as an urging means. As the piezoelectric actuator 4 of this embodiment, it is preferable to use a laminated type. In this piezoelectric actuator 4, the displacement amount changes in proportion to the value of the applied voltage, and the lead screw 3 is disposed in the displacement portion.
The tip of No. 4 is in contact.

The leaf spring 5 has a fixing portion 51 for fixing it to the housing 1a side at its base end, and a contact surface 52 for vertically contacting the base end 342 of the lead screw 34 at its tip end. And the lead screw 34 at the contact surface 52.
Is urged toward the piezoelectric actuator 4 direction. Even if the lead screw 34 is displaced in the thrust direction by the piezoelectric actuator 4, the contact surface 52 always contacts the lead screw 34 and urges it. The urging means may be any means that urges the lead screw 34 toward the displacement means 4, and may be a leaf spring or a coil spring, for example.

When the piezoelectric actuator 4 is driven, the lead screw 34 is displaced in the thrust direction,
The moving parts of the transport system 3 are integrated to form the lead screw 3
Displaces with 4. As a result, the CCD line sensor 2 is displaced. The sub-scanning speed can be controlled to be constant by adjusting the displacement amount according to the variation in the moving speed of the lead screw 34. The piezoelectric actuator 4 and the leaf spring 5 may be provided at positions opposite to each other.

A photo interrupter 39 is provided as a position detecting means for detecting the initial position of the CCD line sensor 2 at a lateral position of the transport system 3 having the above-described structure. In this photo interrupter 39, a light emitting portion and a light receiving portion are arranged at opposite positions with a predetermined gap 391,
When the object to be detected is inserted into the gap 391 to block the light incident from the light emitting unit to the light receiving unit, the output of the signal from the light receiving unit is stopped. On the other hand, at the end of the carriage 31, the detected portion 3
10 is provided so as to project laterally. The detected part 310 is located in the gap 391 of the photo interrupter 39 at the initial position of the CCD line sensor 2, and C
It is detected that the CD line sensor 2 is at the initial position.

The position detecting means is not limited to the photo interrupter 39, and may be, for example, a magnetic detecting means, a mechanical stopper or a switch. The initial position is
It may be a movement start position where the CCD line sensor 2 starts to move or a reading start position where reading of the document P starts. In the apparatus of this embodiment, the initial position is CC
It is the starting point where the movement of the D line sensor 2 is started. This initial position serves as a reference position for identifying a correction position for correcting the random walk error of the lead screw 34.

In the apparatus of this embodiment, when correcting the variation in the moving speed in the sub-scanning direction, the amount of displacement of the piezoelectric actuator 4 is stepwise (digitally) in units of a fixed predetermined time. It is changing. By this operation, the movement amount of the transport system 3 per predetermined time is controlled so that it is always substantially constant. This predetermined time can be, for example, one main scanning time, or an accumulation time until the charge accumulated in the CCD line sensor reaches a required video level. In the device of the present embodiment, one cycle of the CCD shift pulse (accumulation time) as described later.
The voltage applied to the piezoelectric actuator 4 is changed step by step with 1 as a unit (see (e) in FIG. 5).
The displacement amount may be changed in an analog manner.

The cycle for changing the displacement in stages is
In addition to the above, the CCD shift pulse may be set every 3/2 cycle, every 2 cycles, or every 1/2 cycle, and is not particularly limited.

In the apparatus of this embodiment shown in FIG. 1, the relationship between the displacement amount and displacement direction of the piezoelectric actuator 4 and the random walk error of the lead screw 4 can be set as follows, for example. The random walk error of the lead screw 4 is based on a position where the carriage 31 should originally be located (hereinafter referred to as “ideal position”) (ideal line B in FIG. 10), which is a plus side error (error toward the sub-scanning direction side). Error) and the error on the minus side (when there is an error on the side opposite to the sub-scanning direction), the minus side has the largest absolute value and the plus side has the largest absolute value. The maximum displacement amount of the piezoelectric actuator 4 is set to be larger than the sum of the absolute value and the error.

Then, for example, when correcting an error having the largest absolute value on the minus side, the displacement amount of the displacement portion of the piezoelectric actuator 4 in the protruding direction is set to be the smallest, or the absolute value on the plus side is the most absolute. When correcting an error with a large value, the displacement amount of the displacement portion of the piezoelectric actuator 4 in the protruding direction is set to be the largest. As another setting pattern, the displacement amount of the piezoelectric actuator 4 that corrects the error amount when the sum of the errors having the largest absolute values on the plus side and the minus side is divided into two is the maximum displacement amount. The amount may be set to one half.

Next, the structure of the control system of the image input apparatus will be briefly described. FIG. 3 is a simplified block diagram of electric circuits of a drive system and a data transmission system of the image input device 1 of the first embodiment. The circuit of the device of the first embodiment is controlled by the system control 10. Carriage 31
The moving speed of is maintained substantially constant by controlling the DC motor 38 at a constant speed by the servo circuit 11. The servo circuit 11 uses the pulse interval from the encoder 381,
The rotation speed of the DC motor 38 is detected, and the DC
The motor 38 is controlled.

The system control 10 controls the start and stop of the drive of the DC motor 38 and the forward / reverse rotation via the servo circuit 11. In addition, by counting the pulses transmitted from the encoder 381, the CC
The movement amount (sub-scanning position) of the D line sensor 2 can be specified.

The CCD drive circuit 26 is a CCD circuit 220.
A CCD shift pulse is also transmitted to, and a CCD drive pulse is also transmitted. The piezoelectric drive circuit 14 outputs a voltage for displacing the piezoelectric actuator 4 so that the piezoelectric actuator 4 can obtain a desired displacement amount. This voltage is sequentially controlled by the system control 10. Then, the sub-scanning position of the CCD line sensor 2 is specified by the transmission pulse from the encoder 381, and the applied voltage is applied so that the displacement amount of the piezoelectric actuator 4 that cancels the random walk error at that position is obtained.

Corresponding to the sub-scanning position of the carriage 31,
The data on the applied voltage of the piezoelectric actuator 4 is
It is stored in advance in the memory 10b and is read by the system control 10 from the memory 10b. This memory 1
0b can be composed of, for example, an EPROM.

The correction data is input to the memory 10b by, for example, precisely measuring a random walk error during sub-scanning with a laser range finder at the time of manufacturing the apparatus, and determining the random walk error at each sub-scanning position. Then, the correction data for each sub-scanning position (for each reading time) is obtained and input. When measuring the error with the laser range finder, if the amount of movement of the CCD line sensor 2 is directly measured and the error from the ideal position is measured, not only the random walk error of the lead screw 34 but also the scratch formed in the screw groove Absorb mechanical errors of movable parts caused by unique mechanical properties and combinations of mechanical components such as an error in engagement between the lead screw 34 and the nut 33 and an error caused by the inertia of the carriage 31. It is desirable because a correction value can be obtained. Here, the lead error means not only a random walk error but also an error caused by the lead screw 34 such as an error caused by a scratch on the lead screw 34.

The type of information (SD) (see (c) in FIG. 5) stored in the memory 10b is, for example, data of the position of the CCD line sensor 2 with respect to the rotation amount of the DC motor 38, each sub-data. For the amount of error between the ideal position at the scanning position and the measured position of the CCD line sensor 2, each measured value from the reference position to each sub-scanning position, and the count number of the transmission pulse from the encoder between the sub-scanning positions,
The distance data obtained by the distance measurement during that period, the applied voltage value of the piezoelectric drive circuit for each sub-scanning position, and the like can be given.

Further, the detection circuit 13 has the above-mentioned photo interrupter 39. When the photo interrupter 39 detects that the CCD line sensor 2 is located at the initial position, it outputs an initial position detection signal to the system control 10. (See (a) in FIG. 5).

On the basis of this initial position detection signal, the system control 10 drives the DC motor 38 for driving the lead screw 34 in the forward direction to generate a load pulse for reading data from the memory 10b and a CCD shift pulse (FIG. 5). (See (d) and (f)).

Further, the transmission pulse of the encoder 381 is counted from the initial position detection signal to judge that the CCD line sensor 2 has reached the reading start position, and the CCD
Send a shift pulse.

The above operation will be described with reference to the flow chart shown in FIG. 4 and the timing chart shown in FIG. In the first reading operation, the DC motor 38 is rotated in the reverse direction to move the carriage 31 (CCD line sensor 2) in the direction opposite to the sub-scanning direction (step 101). When the CCD line sensor 2 reaches the initial position, that is, the movement start position of the carriage 31, the carriage 31
Since the detected portion 310 of FIG. 5 is detected by the photo interrupter 39 and outputs an initial position detection signal (see FIG.
(A)) In the next step 102, it is judged whether or not the initial position detection signal is transmitted from the detection circuit 12, and if it is not output, step 101 is executed again.

When the initial position detection signal is output,
The system control 10 initializes the address of the memory 10b (step 103), and the CCD circuit 220
Is performed for initializing (step 10
4). By this step 104, in the CCD line sensor 2, the charges accumulated in the photodiode are read out and initialized, and the data in the register are also initialized.

Next, the DC motor 38 is normally rotated by constant speed control (step 105). This constant speed control is performed based on the transmission pulse (FIG. 5 (b)) output from the encoder. As a result, the CCD line sensor 2 starts moving in the sub scanning direction. The CCD line sensor 2 moves in the approach section until the rotation of the DC motor 38 becomes stable and the moving speed becomes stable by the constant speed control of the servo circuit 11. That is, the approach section is from the movement start position to the reading start position.

Each time the CCD line sensor 2 moves a distance corresponding to one sensor pitch in the sub-scanning direction from the initial position, a load pulse is transmitted (FIG. 5 (d)), and the correction data ( 5 (c)) is read (step 106). Based on the read correction data,
The voltage applied to the piezoelectric actuator 4 during the accumulation time is determined (FIG. 5E), and the piezoelectric actuator 4 is driven by the voltage output from the piezoelectric drive circuit 14 (step 107). By driving this piezoelectric actuator 4, the carriage 3 in one sensor pitch
The variation (error) in the movement amount of 1 is almost canceled. This error correction is performed from the movement start position where the CCD line sensor 2 moves.

A CCD shift pulse is output (step 108) (FIG. 5 (f)). As a result, the reading (main scanning) by the CCD line sensor 2 is started, and the charge starts to be accumulated in the photodiode. The accumulation time, that is, the reading time is constant and is set to, for example, about 1 to 10 msec. In the apparatus of this embodiment, the correction data is stored for each reading time, the driving amount of the piezoelectric actuator 4 is digitally controlled for each reading time, and the carriage 31 moves by one sensor pitch at this reading time. The sub-scanning speed is set so that

At the same time, a CCD drive pulse is transmitted to CC
The read information read in the immediately preceding main scan stored in the register of the D circuit 220 is read out for each pixel and C
Configure and output CD output signal (step 109)
(FIG. 5 (g)). This signal is input to the signal processing circuit 9 and processed.

Next, it is judged whether or not a predetermined number of main scanning lines have been read (step 110). If the number of lines has not reached the predetermined number, the process returns to step 106, and if the number has reached the number, the reading operation is stopped. The above step 10 is performed every one sensor pitch or every time one main scan is performed.
The operations from 6 to step 109 are repeated to read one screen.

Here, it may be set to return to the initial position and wait after the reading is completed. Further, if it takes time to stabilize the light amount of the light source after the switch is turned on, the power source of the light source is kept on even after the reading operation is completed.

As can be seen from the timing chart of FIG. 5, the transmission of the load pulse, the driving of the piezoelectric actuator 4, and the transmission of the CCD shift pulse are performed substantially in synchronization, and one cycle of the CCD shift pulse is set as a digital unit. Then, the movement amount of the carriage 31 is corrected.

FIG. 6 is a graph showing the relationship between the movement amount of the carriage 31 and the rotation angle of the lead screw 34 when the movement amount of the carriage 31 is corrected in this way. As shown in the figure, it can be confirmed that the carriage 31 moves with a substantially constant amount of movement in proportion to the rotation angle.

As can be seen from FIGS. 6 and 10, the random walk error is that the lead screw 34 makes one rotation (2
π), the correction data is set so as to cancel the random walk error for one cycle, and this data may be repeatedly used each time the lead screw 34 makes one rotation. it can.

In the above construction, if a stepping motor is used to drive the lead screw 34, ringing or step-out phenomenon occurs, which is not suitable for use as a driving means. Further, if the drive speed of the DC motor 38 is directly controlled to control the random walk error, the servo mechanism becomes complicated. Compared with such a mechanism, the above-described configuration has an advantage that not only the sub-scanning can be performed at high speed but also the mechanism is simple. Further, since it is not necessary to perform the random walk correction during the pre-scan, the structure is driven at a higher speed. be able to.

The CCD output signal thus transmitted is processed by the signal processing circuit 9 described above. The signal processing circuit 9 will be briefly described below with reference to FIG. CC
The CCD signal output from the D circuit 220 is red (R),
The signals of green (G) and blue (B) are separately output. Each output signal is inverted and amplified by the head amplifier 91 and output (FIG. 5 (h)). For each color signal (R, G, B)
To the dark uniformity (hereinafter referred to as “DU”) correction circuits 92R, 92G, and 92B.
The DU correction circuits 92R, 92G, and 92B correct noise generated by dark current. Since this error differs for each pixel, each value is read from the DU memory 92M and corrected for each pixel. At this time, since each correction amount is digitized and stored, after the memory value is D / A converted, the correction amount for each pixel is calculated.
Input to 2R, 92G, 92B.

Next, the CCD signal is supplied to the white uniformity (hereinafter referred to as "WU") correction circuits 93R and 93G.
It is input to 93B respectively. This WU correction circuit 93
In R, 93G, and 93B, noise caused by the sensitivity difference for each pixel is corrected. Since this correction amount differs for each pixel, each value is read from the WU memory 93M and corrected for each pixel. At this time, since each correction amount is digitized and stored, after the memory value is D / A converted, the correction amount for each pixel is calculated by the WU correction circuits 93R and 93G.
Input to 93B. Next, the CCD signal is subjected to shading (hereinafter referred to as "SD") correction circuits 94R, 94G, 94.
Input to B respectively. Since the intensity of the light source differs depending on the position of the pixel, the SD correction circuits 94R, 94G, and 94B perform nonuniform correction of the optical system such as the light source and the lens. Since this correction amount varies depending on the position of each pixel, each value is read from the SD memory 94M and corrected for each pixel. At this time, since each correction amount is digitized and stored, after the memory value is D / A converted, the correction amount for each pixel is calculated by the SD correction circuits 94R and 94R.
Input to G and 94B.

Next, the CCD signal is supplied to the automatic white balance (hereinafter referred to as "AWB") circuits 95R, 95G, 95.
Input to B respectively. This AWB circuit 95R, 95
In G and 95B, the sensitivity difference and the change in color temperature of the light source are corrected for each of the R, G, and B signals. This is each A
This is performed by variably adjusting the amplification degree of the WB circuits 95R, 95G, and 95B. These AWB circuits 95R and 9R
The variable adjustment of the amplification degree between 5G and 95B is performed by the AWB control circuit 95C.

Next, the CCD signal is input to the density correction circuit (hereinafter referred to as "γ correction circuit") 96R, 96G, 96B. This γ correction circuit 96R, 96G, 96
In B, the γ characteristic is corrected according to the output device, and the recordable dynamic range is expanded. The operation of the above process is controlled by the system control 10. This system control 10 has an operation panel 10a.
It is operated externally via.

The CCD signals processed as described above are input to A / D conversion circuits 97R, 97G and 97B, respectively. Each of the R, G, and B CCD signals is converted into a digital signal and, for example, as shown in the drawing, is transmitted to the high-definition frame memory simultaneously by the interface 15 for each color.

Alternatively, it is output to the photographing monitor system 16. In the imaging monitor system 16, R, G,
The B signals are transmitted to the frame memories 16R and 16R, respectively.
The information is input to G and 16B, processed into information in which the number of pixels is reduced to, for example, 1/10 in accordance with the TV monitor, and output to the monitor 16b via the D / A conversion circuit 16a.

Alternatively, SCSI (Small Cmputer System)
Interface) circuit 17 to input to a hard disk drive device 18a or a magneto-optical disk device 18b,
Information may be recorded. Further, it may be input to a personal computer (PC) or an engineering workstation (EWS) 18c and output to the monitor 19.

FIG. 8 is an internal perspective overall perspective view showing the structure of the image input apparatus 1 of the second embodiment.
In the second embodiment, a pair of opposing leaf springs 53a and 53b are erected in parallel on the carriage 31 as biasing means, and the CCD line sensor 2 is provided between the leaf springs 53a and 53b. It is pinched. The leaf springs 53a, 5
3b is formed by bending one leaf spring 53 so that its cross section has a U-shape. And this leaf spring 53
Is mounted on the carriage 31 in a posture such that the upper side is opened, and the bottom is fixedly provided on the carriage 31.

On the other hand, on the carriage 31, the C
On the side of the CD line sensor 2 in the sub-scanning direction, a mounting portion 311 for mounting the piezoelectric actuator 4 as a displacement means is provided in a protruding manner. The piezoelectric actuator 4 is attached to the attachment portion 311 so as to face the CCD line sensor 2.

By the action of the piezoelectric actuator 4,
The CCD line sensor 2 is displaced in the sub-scanning direction and the direction opposite to the sub-scanning direction. At this time, the pair of leaf springs 53a, 5
Each upper end holding the CCD line sensor 2 of 3b is
The CCD line sensor 2 is bent by the same amount of displacement in the direction opposite to the sub-scanning direction, and the CCD line sensor 2 sandwiched therebetween is configured to move in parallel. The CCD line sensor 2 is constantly urged toward the piezoelectric actuator 4 by the restoring force of the leaf springs 53a and 53b. The rate of increase of the displacement amount of the piezoelectric actuator 4 and the lead screw 3
The relationship with the moving speed of the carriage 31 according to No. 4 is the same as in the case of the configuration of the above-described first embodiment, and therefore will be omitted.

A pair of parallel guide members 32a and 32b are slidably inserted in the carriage 31. A nut 33 is provided at the end of the carriage 31, and a lead screw 34 is screwed into the nut 33. The lead screw 34 is rotatably supported and has a DC motor 3 having an encoder built in at one end thereof.
8 is connected. The rest of the configuration is the same as that of the first embodiment and will not be described.

In the second embodiment having such a structure, the structure of the drive system is simple, and the manufacturing cost is low. Further, since the CCD line sensor 2 is directly displaced, the inertia during displacement movement is further reduced, the drive speed of displacement driving of the CCD line sensor 2 is increased, and the responsiveness is further improved. Therefore, the error correction can be achieved with higher accuracy.

The electric circuit configuration of the drive system and the data transmission system of the image input apparatus 1 of the second embodiment having the above-mentioned configuration is as follows.
It shows in FIG. In the device of the second embodiment, the operation of the piezoelectric actuator 4 directly acts on the CCD line sensor 2. The rest of the configuration on the circuit is the same as that of the first embodiment and will not be described. The content of the signal processing circuit 9 for processing the CCD signal is also the same as that of the first embodiment, and therefore its description is omitted.

In the embodiment described above, the reflected light from the original P is read by the CCD line sensor 2, but the transmitted light from the original P may be read. In this case, for example, the document holder 1b may be provided with a light source. The light source may be, for example, a planar light emitting body having a light emitting area sufficient to illuminate the entire surface of the original P.

The original P read by the apparatus of the present invention has a small area, specifically, 432-5.
It is particularly useful for reading a document having an area of about 1562 mm ² in high definition.

Specific examples thereof include photographic prints, developed black and white films and color films, and negative and positive films thereof. In particular, when reading a film, it is preferable to use a configuration in which the transmitted light of the film is read.

The sizes of these originals are, for example, 18 to 2 vertically.
A document with a size of 03 mm and a width of 24 to 254 mm, especially a film, can be read with a particularly high-definition image. In the above two embodiments, the reduction type CCD was used, but it is needless to say that the contact type CCD can be used. Further, the image input device 1 of the present invention can be used for various image inputs such as a copier and a facsimile in addition to an image scanner.

[0070]

As described above, according to the image input apparatus of the present invention, since the moving speed of the reading unit can be kept constant with high accuracy, high-definition image information can be read. Further, since the transport system can be continuously moved at high speed, there is an advantage that the sub-scanning can be completed in a short time.

[Brief description of drawings]

FIG. 1 is an overall internal perspective view showing the structure of an image input device according to a first embodiment.

FIG. 2 is a lateral cross-sectional side view of a CCD line sensor.

FIG. 3 is a simplified block diagram of electric circuits of a drive system and a data transmission system of the image input device of the first embodiment.

FIG. 4 is a flowchart showing an operation of system control when controlling speed control and reading by a CCD line sensor.

FIG. 5 is a timing chart showing the drive timing of each circuit.

FIG. 6 is a graph showing the relationship between the rotation amount of the lead screw and the movement amount of the carriage when the random walk error of the lead screw is corrected by the apparatus of the present invention.

FIG. 7 is a block diagram showing a configuration of a signal processing circuit.

FIG. 8 is an internal perspective overall perspective view showing the structure of the image input apparatus of the second embodiment.

FIG. 9 is a simplified block diagram of electric circuits of a drive system and a data transmission system of the image input device of the second embodiment.

FIG. 10 is a graph showing a relationship between the rotation amount of the lead screw and the movement amount of the carriage, which shows a random walk error in the conventional sub-scanning mechanism.

[Explanation of symbols]

1 Image Input Device 1a Housing 1b Document Presser 2 CCD Line Sensor 21 Thick Film Ceramic Substrate 22 CCD Chip 220 CCD Circuit 23 Condensing Rod Lens Array 24 Light Emitting Diode 25 Case 251 Window 26 CCD Drive Circuit 3 Transport System 31 Carriage 310 Detected Part 311 Mounting part 32a, b Guide member 33 Nut 34 Lead screw 341 Tip 342 Base end 35a, b Bearing 36 Driven gear 37 Drive gear 38 DC motor 39 Photo interrupter 391 Gap 4 Piezo actuator 5 Leaf spring 51 Fixed part 52 Contact surface 53a, b Leaf spring 9 Signal processing circuit 91 Head amplifier 92 Dark uniformity (DU) correction circuit 93 White uniformity (WU) correction circuit 94 Shading (SD) correction circuit 9 Auto white balance (AWB) circuit 96 Density correction circuit (γ correction circuit) 97 A / D conversion circuit 10 System control 10a Operation panel 10b Memory 11 Servo circuit 12 Detection circuit 14 Piezoelectric drive circuit 15 Interface 16 Imaging monitor system 16a D / A conversion circuit 16b monitor 17 SCSI circuit 18a hard disk drive device 18b magneto-optical disk device 18c personal computer (PC), engineering workstation (EWS) 19 monitor P manuscript 101-110 steps

Claims (6)

[Claims] 1. A reading unit provided facing a document and having a photoelectric conversion element for reading reflected light or transmitted light from the document arranged in the main scanning direction; and a sub unit that crosses the reading unit orthogonal to the main scanning direction. A transport system that continuously moves in the scanning direction, and a displacement unit that displaces the reading unit in the sub-scanning direction or a direction opposite to the sub-scanning direction, and the displacement unit causes the reading unit by the transport system. An image input device, wherein the reading unit is displaced so as to cancel the variation in the moving speed of the image reading device. 2. A control means for controlling the operation of the displacing means, and a memory for storing in advance information for correcting an error in the moving speed of the reading section by the transport system, the control means comprising: The image input device according to claim 1, wherein the displacement means is controlled based on information from the memory. 3. The image input device according to claim 1, further comprising a position detection unit that detects an initial position of the reading unit. 4. The carriage system includes a carriage on which the reading unit is mounted and which is movably supported in a sub-scanning direction, a nut provided on the carriage, a lead screw screwed to the nut, and the lead screw. 4. The driving means for driving the moving system, wherein the variation of the moving speed is caused by a mechanical error of each component of the transport system.
The image input device according to any one of 1. 5. The image input device according to claim 4, wherein the mechanical error is mainly a lead error of a lead screw. 6. The image input device according to claim 4, wherein the operation pattern of the displacement means is repeated in units of one rotation cycle of the lead screw.