JP2002199158A - Image reader and image read method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader and image read method which can read a document, even in the middle of acceleration/deceleration and can restart reading immediately from a position of temporary stop, after a temporary stop. SOLUTION: In the image reader which reads a document image in one- dimensional direction by a line sensor and moves the line sensor in the direction orthogonal to this one-dimensional direction relative to the document image, the amplification factor of a signal inputted to an A/D converter is changed in inverse proportion to the light storage time of the line sensor in the middle of acceleration/deceleration during this movement, when the light storage time is changed. Thus the influence of acceleration/deceleration upon digital data is eliminated, and the document can be read, even in middle of acceleration/ deceleration.

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 and method, and more particularly to an image reading apparatus and method for reading an image of an entire original by moving the original or a reading mechanism.

[0002]

2. Description of the Related Art Conventionally, an image reading apparatus includes a method of reading an image while moving a document while fixing a line sensor and a method of reading an image while moving the document on a flat platen. There is a reading method. In any of these image reading devices, in a device using a CCD sensor, when reading of a document is started, the document (reading mechanism) is moved at a constant speed until the end of the document, and the image is not stopped at once without stopping. Is read and read.

As another method, an image is read by using a stepping motor in accordance with an excitation pulse of the stepping motor, and is configured and controlled so that the image can be temporarily stopped after the image reading is started. There was also. However, with the increase in speed and definition, it has become necessary to increase the reading speed, and the rotational speed of the stepping motor must be increased. However, when the rotation speed of the stepping motor is high, it is necessary to perform a slow-up process at the time of startup and a slow-down process at the time of stop, and it is difficult to read an image during the slow-up and slow-down.

[0004]

However, in the above-mentioned first method of the prior art, when the reading speed of an image is increased, an image processing section for processing the read image is formed so as to correspond to the speed. However, there is a problem that the price of the product is increased due to the improvement of the performance of the image processing unit.

In the second method, not only is it impossible to read an image during slow-up or slow-down, but if the image is temporarily stopped, the original or reading mechanism is moved in the reverse direction to return to the original position, and then reading is resumed. There is a problem that must be done.

The present invention has been made under such circumstances, and an image reading apparatus and a reading method capable of reading a document even during acceleration / deceleration of a relative movement of a line sensor for reading a document image. The purpose is to provide.

[0007]

In order to achieve the above object, according to the present invention, an image reading apparatus is provided with the following (1) to (4).
And the image reading method is as follows (5) and (6)
Configure as follows.

(1) A line sensor for reading a document image in a one-dimensional direction, moving means for moving the line sensor relative to the document image in a direction orthogonal to the one-dimensional direction, On the other hand, timing generating means for generating a timing for synchronizing a signal for controlling reception and reading of one line of image data with the operation of the moving means, and amplifying means for amplifying an analog signal read from the line sensor And a gain control means for controlling the gain of the amplifying means. During the acceleration and deceleration of the moving means, the gain of the amplifying means is changed by the gain control means during acceleration, An image reading device that reads the document image even during deceleration.

(2) The image reading apparatus according to (1), wherein the amplification factor control means sets the amplification factor of the amplification means to a value inversely proportional to the light receiving time at the line sensor.

(3) A line sensor for reading a document image in a one-dimensional direction, moving means for relatively moving the line sensor in a direction perpendicular to the one-dimensional direction, and one line for the line sensor. Timing generating means for generating a timing for synchronizing a signal for controlling light reception and reading of image data with the operation of the moving means, and A / D converting means for converting an analog signal output from the line sensor into a digital value; Multiplying means for performing an operation of multiplying the digital value converted by the A / D converting means by a required magnification, and magnification control means for controlling the magnification of the multiplying means, while the moving means is accelerating and decelerating. An image reading apparatus for reading the document image during acceleration and deceleration by changing the magnification of the multiplication means by the magnification control means.

(4) The image reading apparatus according to (3), wherein a magnification of the multiplying means is a value inversely proportional to a light receiving time of the line sensor.

(5) reading an original image in a one-dimensional direction by a line sensor; moving the line sensor relative to the original image in a direction orthogonal to the one-dimensional direction; 1 for
Synchronizing a signal for controlling the reception and reading of image data for the line with the movement of the line sensor;
An image reading method, comprising: amplifying an analog signal read from the line sensor by an amplifying unit; and changing an amplification factor of the amplifying unit during acceleration and deceleration of the movement of the line sensor.

(6) reading an original image in a one-dimensional direction by a line sensor; moving the line sensor relative to the original image in a direction orthogonal to the one-dimensional direction; Synchronizing a signal for controlling the reception and reading of one line of image data with the movement of the line sensor;
Converting the analog signal output from the line sensor into a digital value, and performing an operation of multiplying the digital value converted in this step by a required magnification;
Changing the required magnification during acceleration and deceleration of the movement of the line sensor.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to embodiments of an image reading apparatus. The present invention is not limited to the image reading apparatus, but can be implemented in the form of an image forming method, supported by the description of the embodiments.

[0015]

(Embodiment 1) FIG. 1 is a sectional view showing the structure of an "image reading apparatus" according to Embodiment 1. In FIG.
201 is an original, 202 is a transparent original plate such as glass, 20
Reference numeral 3 denotes a light source for irradiating the document 201; 204, a reflection mirror; 205, a condenser lens; 206, a line sensor such as a CCD for converting received light into an electric signal corresponding to the intensity; An image data generation unit 208 for generating image data from the output electric signal, 208
Denotes a light source 203, a reflection mirror 204, a condenser lens 205,
An optical unit 209 including the line sensor 206 is an optical unit driving motor for driving the optical unit 208 and uses a stepping motor. A home position sensor 210 detects that the optical unit 208 is at a position (home position) where image reading can be started.
Reference numeral 11 denotes an automatic document feeder (ADF) for continuously reading a plurality of documents;
A stepping motor is used as the DF drive motor. 2
Reference numeral 13 denotes a controller that controls the entire image reading apparatus such as the optical unit 208, the optical unit drive motor 209, and the ADF 211.

When the image reading apparatus receives a user operation of a start button or an image reading start signal sent from a host (not shown), the controller 213 informs the home position sensor that the optical unit 208 is at the home position. After confirmation at 210, the image reading operation is started.

A light source 203 illuminates a document 201 set on a document table 202. The light reflected by the original 201 passes through a reflection mirror 204 and is condensed by a condenser lens 205.
After that, the light enters the line sensor 206. The incident light is converted by the line sensor 206 into an electric signal corresponding to the light intensity. The image data generation unit 207 generates image data corresponding to one line of the document based on the electric signal. The details of this block are shown in FIG. 3, which will be described later.

The controller 213 drives the optical unit drive motor 209 simultaneously with the start of the reading operation to generate the image data for each line while moving the optical unit 208 at a constant speed in the sub-scanning direction, so that the entire document 201 is generated. Perform image reading. The image data generated by the image data generation unit 207 is sequentially transmitted to a host, an image forming apparatus, and the like via the controller 213.

In the case of continuously reading a plurality of originals using the ADF 211, the controller 213 controls the optical unit 2
08 is stopped at a predetermined position, and the ADF drive motor 212 is driven to convey the documents 201 set on the ADF 211 one by one at a constant speed. The document 201 passes through the optical unit 208 stopped on the transport path, is discharged to a predetermined paper discharge port, and the next document 201 is sequentially transported. Optical unit 2
Reference numeral 08 performs an image reading operation similar to that described above when the document 201 passes through, and generates image data.

Next, the operation of the line sensor 206 will be described with reference to the timing chart of FIG. The line sensor 206 has two input signals and one output signal. The input signal is a start pulse signal (SP signal),
The data shift signal (SFT signal) and the output signal are data signals (Vout signal). A pulse is input to the SP signal, and during a period of one cycle from the previous pulse (timing T301) to the next pulse (timing T302),
The reflected light applied to the document 201 is received, the amount of light received at the pulse (timing T302) is stored, and the reception of the reflected light is newly started. The amount of light currently held is S
It is converted into a voltage for each pixel by the FT signal, and Vou
It is output from the t signal. Therefore, a pulse corresponding to the number of pixels in one line is applied to the SFT between the SP signal and the next SP signal.
The image data is read out by inputting the signal.

In this embodiment, as shown in FIG. 2, the optical unit drive motor 209 or the ADF drive motor 2
During normal rotation of the drive motor 12 (hereinafter collectively referred to as a drive motor), control is performed such that the pulse of the SP signal and the switching of the excitation pattern of the drive motor are synchronized to read the image of the document.

The analog signal of the image data sent from the line sensor 206 is output to an image data generation unit 207.
Is input to FIG. 3 is a block diagram illustrating a configuration of the image data generation unit 207. The image data processing generation unit 207 performs required processing and calculation, converts the data into digital data, and sends the digital data to the controller 213.

That is, the analog signal of the image data sent from the line sensor 206 is amplified by the amplifier 301. The amplification factor at this time is determined by the amplification factor control circuit 302.
Is controlled by The amplified signal is A /
The data is converted into digital data (for example, 10 bits) by the D converter 303. When data for shading correction is adopted, the data is appropriately stored in the black data storage memory 304 and the white data storage memory 305. When reading the original data, the subtracter 3
At 06, the subtraction process of the black reference data is performed, and at the divider 307, the division by the white reference data is performed to correct the digital data.

Further, in this embodiment, data is read during acceleration and deceleration of the drive motor by the following method. This method will be described with reference to the flowchart of FIG. 4 and the timing chart of FIG.

When the power of the image reading apparatus is turned on, motor rotation control and reading control (control in the flowchart of FIG. 4) and other controls (not shown) are started. First, an SP signal is output to the line sensor 206 in step 401 (abbreviated as S401 in FIG. 4, hereinafter the same). Then, it is determined in step 402 whether or not the motor should be rotated by a timer. If the motor is to be rotated (timer stopped), a motor excitation pulse is advanced by one step in step 403. Then, in step 404, the output of the SFT signal is started, and the transmission of the image data accumulated in the line sensor is started. If the timer is in operation in step 402, the process proceeds to step 404, and data is read out even when the motor is stopped so as not to saturate the light accumulation amount of the CCD. In step 405, a timer for the time until the next motor excitation is started. Even while the motor is stopped,
A timer for a predetermined time is started to output the SP signal and the SFT signal. Details of the setting value will be described later. Then, in step 406, the process waits until the timer stops, that is, until the set time has elapsed. After the set time has elapsed, a value inversely proportional to this time is set as the amplification factor of the amplifier. This amplification factor is determined by the following SFT
This is applied to reading of data by a signal. This is because the transmission of data from the line sensor is delayed by one line with respect to the accumulation of light.

Then, returning to step 401, the operation for the next line is repeated.

A specific example will be described with reference to the timing chart of FIG. In the present embodiment, an example will be described in which a slow-up is started from 400 pps and 800 pps is set to a steady rotation.

First, the motor is excited and the SP signal is output.
2.50 msec (equivalent to 400 pps) is set in the timer. This time is a time until the next SP signal is output, and is a time for storing light (reflected light of image data) in the line sensor. When 2.50 msec has elapsed,
Set the amplification factor of the amplifier to 1.5 times.

Next, the excitation pattern advanced by one step and the SP signal are output, and the timer outputs 1.87 msec (5
35 pps). Then, the SFT signal is set to 1
Output is performed for the number of pixels in the line, and the image data stored in the line sensor is sequentially read out, the signal is amplified by the amplifier 301, and converted into digital data by the A / D converter 303. At this time, the amplification factor of the amplifier is 1.5 times. When 1.87 msec has elapsed, the amplification factor of the amplifier is set to 2.0 times.

Similarly, in the output of the excitation pattern,
The timer is set to 1.56 msec (corresponding to 641 pps), and after that time, the amplification factor of the amplifier is set to 2.4 times. In the output of the excitation pattern, the timer is set to 1.39.
msec (equivalent to 719 pps) is set, and after that time, the amplification factor of the amplifier is set to 2.7 times. In the output of the excitation pattern, the timer is set to 1.25 msec (800 p.
ps), the amplification rate is set to 3.0 times, and the state is changed from the acceleration state to the steady rotation state. In the excitation pattern of the steady rotation state, the same value as the excitation pattern is set, and image data reading, amplification, and A / D conversion are performed.

At the time of deceleration, similarly, the excitation pattern circle 10 (circle 10 and subsequent circles cannot be used as a circle code such as "" due to rules, so they are represented as "circle 10". However, in FIG. 5, they are represented by circle symbols. ): Timer 1.39 msec, amplification factor 2.7 times Excitation pattern circle 11: Timer 1.56 msec, amplification factor 2.4 times Excitation pattern circle 12: Timer 1.87 msec, amplification factor 2.0 times Excitation pattern Circle 13: Timer 2.50 msec, amplification factor 1.5 times Excitation pattern Circle 14: Timer outputs 2.50 msec, amplification factor 1.5 times, and stops.

The relationship between the time of one line and the amplification factor is set to be inversely proportional.

2.50 msec × l. 5 times = 3.75 1.87 msec × 2.0 times ≒ 3.75 1.56 msec × 2.4 times ≒ 3.75 1.39 msec × 2.7 times ≒ 3.75 1.25 msec × 3.0 times = 3.75 As described above, the level of the signal output from the amplifier 301 is always the same by changing the amplification factor of the amplifier 301 by the amplification factor control circuit 302 according to the time for accumulating data in the line sensor. Signal level. That is, image data can be read during acceleration / deceleration without changing the processing of the digital data after A / D conversion from the data processing at the time of steady rotation. The required amplification factor can be calculated by the controller 213 instead of the amplification factor control circuit 302.

As described above, in this embodiment, during acceleration / deceleration in which the light storage time to the line sensor changes,
The amplification factor of the signal input to the A / D converter is changed in inverse proportion to the time. by this,
Acceleration / deceleration can be performed without affecting the image processing portion of the digital data, and the same level of digital data can be obtained even during acceleration / deceleration. As a result, even if a pause process is entered during the reading of the document, the document can be decelerated and stopped while reading the image data, and accelerated while reading the image data from that position.

(Embodiment 2) An "image reading apparatus" according to Embodiment 2 will be described with reference to FIGS. The present embodiment is the same as the first embodiment except for the configuration of the image data generating unit, and therefore will be described with reference to FIGS. 1, 2, 4, and 5 according to the first embodiment.

The configuration of the image reading apparatus shown in FIG. 1 and the operation of the line sensor shown in FIG. 2 are the same as those in the first embodiment, and a description thereof will be omitted. However, since the configuration of the image generation unit is different from that of the first embodiment, a description will be given below with reference numeral 207 as 310. FIG.
FIG. 9 is a block diagram illustrating a configuration of an image data generation unit 310 according to the second embodiment.

The analog signal of the image data sent from the line sensor 206 is supplied to an image data generator 310.
Is input to Then, the processing and calculation shown in FIG.
13 is sent out.

That is, the analog signal of the image data sent from the line sensor 206 is converted by the A / D converter 303 into digital data (for example, 10 bits). Then, the multiplier 308 controls the magnification control means 30.
9 is multiplied by a required magnification set for each line. When data for shading correction is adopted, the data is appropriately stored in the black data storage memory 304 and the white data storage memory 305. When the original data is read, subtraction processing of black reference data is performed by the subtracter 306, and division by white reference data is performed by the divider 307, and digital data is corrected.

Further, in this embodiment, data is read during acceleration and deceleration of the drive motor by the following method. This method will be described with reference to the flowchart of FIG. 4 and the timing chart of FIG.

Most of them are the same as in the first embodiment.
The difference is the step 407 in the flowchart of FIG. In the first embodiment, the amplification factor of the amplifier is set in this step. In the present embodiment, the magnification is set by the magnification control circuit 309 for the multiplier 308. The magnification set at this time is a value that is inversely proportional to the light storage time of the line sensor 206. For example, it may be the same value as the amplification factor for the amplifier of the first embodiment. Note that the required magnification can be calculated by the controller 213 instead of the magnification control circuit 309.

As a result, as the digital value data after the operation of the multiplier 308, data independent of the light storage time of the line sensor can be obtained.

That is, image data can be read during acceleration / deceleration without changing the processing of the digital data after the multiplier 308 from the data processing at the time of steady rotation.

As described above, in the present embodiment, during acceleration / deceleration in which the light storage time to the line sensor changes,
The digital data immediately after the A / D conversion is corrected in inverse proportion to the time. As a result, acceleration and deceleration can be performed without affecting the image processing portion of the digital data, and the same level of digital data can be obtained even during acceleration and deceleration. As a result, even if a pause process is entered during the reading of a document, the document can be decelerated and stopped while reading the image data, and accelerated while reading the image data from that position.

In the above embodiment, the image is scanned by moving the line sensor relatively to the original image. However, the original image and the line sensor are fixed, and the image is formed on the line sensor. The idea of the present invention can be realized by moving an optical system to scan an image. In the embodiment, the original is read during acceleration / deceleration. However, the idea of the present invention can be realized by reading the original during acceleration or deceleration.

[0045]

As described above, according to the present invention,
The original can be read even during acceleration / deceleration in the relative movement between the original image and the line sensor that reads the original image.

As a result, even if the image reading apparatus is used to read a document at high speed, the reading can be resumed immediately from that position.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a first embodiment.

FIG. 2 is a timing chart illustrating an operation of the line sensor according to the first embodiment.

FIG. 3 is a block diagram illustrating a configuration of an image data generation unit according to the first embodiment.

FIG. 4 is a flowchart showing the operation of the first embodiment.

FIG. 5 is a timing chart showing the operation of the first embodiment.

FIG. 6 is a block diagram illustrating a configuration of an image data generation unit according to a second embodiment.

[Explanation of symbols]

 206 Line sensor 207 Image data generator 209 Optical unit drive motor 301 Amplifier 302 Gain control circuit

Continued on front page F term (reference) 5B047 AA01 BB02 BC05 BC09 BC11 CA08 CB07 DA01 DB01 5C051 AA01 BA03 DA03 DB01 DB15 DB22 DB24 DB28 DE03 DE15 DE17 5C072 AA01 BA02 BA17 CA02 DA02 DA04 EA05 FB15 MB08 UA05 UA06

Claims (6)

[Claims] A line sensor for reading a document image in a one-dimensional direction; moving means for relatively moving the line sensor in a direction perpendicular to the one-dimensional direction with respect to the document image; A timing generating means for generating a timing for synchronizing a signal for controlling reception and reading of one line of image data with an operation of the moving means, and an amplifying means for amplifying an analog signal read from the line sensor. A gain control means for controlling the gain of the amplifying means, wherein the gain control means changes the gain of the amplifying means during acceleration and deceleration of the moving means so as to change the gain during acceleration and deceleration. An image reading apparatus for reading the original image even during the reading. 2. The image reading apparatus according to claim 1, wherein
The image reading apparatus according to claim 1, wherein the amplification factor control unit sets the amplification factor of the amplification unit to a value that is inversely proportional to a light receiving time of the line sensor. 3. A line sensor for reading a document image in a one-dimensional direction, moving means for relatively moving the line sensor in a direction orthogonal to the one-dimensional direction, and an image corresponding to one line with respect to the line sensor. Timing generating means for generating a timing for synchronizing a signal for controlling light reception and reading of data with the operation of the moving means, A / D converting means for converting an analog signal output from the line sensor into a digital value, Multiplying means for performing an operation of multiplying the digital value converted by the A / D converting means by a required magnification; and magnification controlling means for controlling the magnification of the multiplying means. An image reading device for reading the document image during acceleration and deceleration by changing the magnification of the multiplication means by the magnification control means. 4. The image reading device according to claim 3, wherein
An image reading apparatus according to claim 1, wherein a magnification of said multiplying means is a value inversely proportional to a light receiving time of said line sensor. 5. A step of reading a document image in a one-dimensional direction by a line sensor, a step of moving the line sensor relative to the document image in a direction orthogonal to the one-dimensional direction, Synchronizing a signal for controlling reception and reading of one line of image data with movement of the line sensor, amplifying an analog signal read from the line sensor by amplifying means, Changing the amplification factor of the amplifying unit during acceleration and deceleration in the movement of the image. 6. A step of reading an original image in a one-dimensional direction by a line sensor, a step of moving the line sensor relative to the original image in a direction orthogonal to the one-dimensional direction, On the other hand, a signal for controlling the reception and reading of image data for one line is
Synchronizing the movement of the line sensor, converting an analog signal output from the line sensor into a digital value, performing a calculation of multiplying the digital value converted in this step by a required magnification, Changing the required magnification during acceleration and deceleration of the movement of the sensor.