CN117896470A - Image reading apparatus and computer-readable storage medium - Google Patents

Abstract

The present invention relates to an image reading apparatus and a computer-readable storage medium. The image reading apparatus includes: an image reading unit configured to perform image reading; a driving unit configured to move a target in image reading; and a signal generating unit configured to generate a signal for driving the image reading unit, the image reading apparatus being configured to acquire image data by the image reading unit performing image reading based on the signal generated by the signal generating unit in a case where the target is moved by the driving unit, wherein the driving unit moves the target such that the target changes at a speed according to a predetermined driving speed profile, and the signal generating unit generates a signal based on the driving speed profile at a timing at which a moving distance of the target is equal intervals.

Description

Image reading apparatus and computer-readable storage medium

Technical Field

The present invention relates generally to image reading apparatuses.

Background

Among image reading apparatuses represented by scanners and the like, there are image reading apparatuses that read images in a period in which the rotation speed of a scanner motor that moves a scanner unit is in a constant speed state and also in an acceleration state or a deceleration state (in other words, the rotation speed is changing) (see japanese patent laid-open No. 5-284284). Such image reading is advantageous for both improving the quality of image data and increasing the acquisition speed of image data.

However, when the change in the rotation speed of the scanner motor is nonlinear, the accuracy of image reading by the configuration described in japanese patent laid-open No.5-284284 may be lowered during the change.

Disclosure of Invention

The present invention, which has been made in light of the knowledge of the inventors of the aforementioned problems, achieves further improvement in the quality of image data and further increase in the acquisition speed of image data in a relatively easy manner.

One of aspects of the present invention provides an image reading apparatus including: an image reading unit configured to perform image reading; a driving unit configured to move a target in image reading; and a signal generating unit configured to generate a signal for driving the image reading unit, the image reading apparatus being configured to acquire image data by the image reading unit performing image reading based on the signal generated by the signal generating unit in a case where the target is moved by the driving unit, wherein the driving unit moves the target such that the target changes at a speed according to a predetermined driving speed profile (profile), and the signal generating unit generates a signal based on the driving speed profile at a timing at which a moving distance of the target is made equal intervals.

Further features of the invention will become apparent from the following description of exemplary embodiments (with reference to the accompanying drawings).

Drawings

FIG. 1 is a perspective view of a multifunction peripheral according to an embodiment;

fig. 2 is a block diagram illustrating a system configuration example of a multifunction peripheral according to an embodiment;

fig. 3 is a block diagram illustrating a configuration example of a driving unit;

fig. 4 is a block diagram illustrating a configuration example of a detection system that can perform image reading;

fig. 5 is a timing chart illustrating an example of waveforms of control signals of the motor control unit;

FIG. 6 is a timing diagram illustrating an example of waveforms of an encoder signal of an encoder;

FIG. 7 illustrates logic in measuring the amount of rotation of a motor;

fig. 8 is a timing chart indicating waveforms of each of the signals in image reading;

fig. 9 is a timing chart for explaining a mode of change in the rotational speed of the motor;

fig. 10 is a timing chart indicating the rotation amount of the motor;

fig. 11 is a diagram indicating a position of a moving target with respect to time when a motor is in an acceleration state;

fig. 12 is a diagram indicating the position of a moving target with respect to time when the motor is in deceleration;

FIG. 13 is a diagram illustrating a relationship between encoder position and read position;

fig. 14 is a diagram illustrating accumulation time in the CIS;

fig. 15 is a timing chart indicating the state of the signal SH in the acceleration state;

fig. 16 is a timing chart indicating the state of the signal SH in the decelerating state; and

fig. 17 is a timing chart of image reading when acceleration reading is not required.

Detailed Description

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following examples are not intended to limit the scope of the claimed invention. In the embodiments, a plurality of features are described, but the invention requiring all such features is not limited, and a plurality of such features may be appropriately combined. In addition, in the drawings, the same or similar configurations are given the same reference numerals, and redundant description thereof is omitted.

Fig. 1 is a perspective view of a multifunction peripheral (MFP) 300 according to an embodiment. MFP 300 includes an image reading unit 310 and a printhead 316 (see fig. 2) that prints an image on a print medium.

Fig. 2 is a block diagram illustrating a system configuration example of the MFP 300. It is assumed that MFP 300 has various functions such as a scanner function of reading an image from a document, a printing function of printing on a printing medium such as paper material. In the present embodiment, MFP 300 includes a control board 301, an image reading unit 310, a printing unit 315, an operation panel 320, and a power supply unit 340.

Although details will be described later, it is assumed that the scanner function includes a function of reading at a document platen and a function of reading using an Automatic Document Feeder (ADF).

The control board 301 includes a control Integrated Circuit (IC) 302, a system bus 303, a ROM 304, and a RAM 305. The control IC 302 includes a microprocessor unit (MPU) 306, a read image processing unit 307, a print image processing unit 308, and an image encoding unit 309, and performs drive control of the entire system while communicating with other components via a system bus 303. The ROM 304 stores information necessary for realizing the functions of the MFP 300, such as program codes, initial value data, and table data for the arithmetic processing of the MPU 306. The RAM 305 serves as a working memory and may be used as, for example, a calculation buffer or an image memory.

The image reading unit 310 includes Contact Image Sensors (CIS) 30 and CIS 31, a read image correction unit 312, and a read system driving unit 313. Any known image sensor (such as a CCD/CMOS image sensor in which a plurality of pixels are arranged, etc.) may be used for the CIS 30 and the CIS 31. The CIS 30 may selectively perform reading of a document at a document platen and reading of a front side of the document using an ADF, and the CIS 30 may be expressed as a front side CIS 30. The CIS 31 may perform reading of the back side of the document using the ADF, and the CIS 31 may be expressed as a back side CIS 31. When image reading is performed on both sides of a document, both the CIS 30 and the CIS 31 will be targets of drive control.

For reading at the document platen, the CIS 30 is caused to scan the document, and for reading by ADF, the document is conveyed relative to the CIS 30 (and CIS 31). In both of the readings, image reading is performed by relatively moving the CIS 30 (and CIS 31) with respect to the document.

The reading system driving unit 313 includes an electric motor that generates power, and the positions of the CIS 30 and the CIS 31 are moved by the power, whereby the CIS 30 and the CIS 31 sequentially read images from a document and convert them into image signals, and generate image data therefrom. The read image correction unit 312 may perform correction processing such as shading correction on the image data thus acquired, and the read image processing unit 307 may perform predetermined image processing on the image data.

Here, the concept of an image that can be read from a document includes not only a tangible object such as a character, a symbol, a graphic, and a photo, but also a blank that can be formed therebetween, and these are collectively referred to as image information in the following description, and acquisition of the image information may be referred to as image reading or image acquisition.

The reading system driving unit 313 may include other power sources required to achieve image reading, in addition to motors or the like configured to shift the positions of the CIS 30 and the CIS 31. Examples of the foregoing may include a motor configured to convey documents, a motor configured to drive rollers that separate and pick up each of the documents for the case of two or more documents, and the like. Further, the reading system driving unit 313 may further include other components required to realize image reading, such as a driver that performs driving control of the CIS 30 and the CIS 31.

The main components that realize the functions of the image reading unit 310 are generally arranged at the upper part of the MFP 300, and a printing unit 315 that prints on a printing medium may be arranged at the lower part of the MFP 300. The printing unit 315 in the present embodiment includes a print head 316, a print signal output unit 317, and a printing system driving unit 318, and performs printing by an inkjet printing method.

The print head 316 is provided with a plurality of nozzles, and ink can be ejected from the plurality of nozzles individually. The printing system driving unit 318 moves the print head 316 to a desired position, and during the movement, the print signal output unit 317 outputs a print signal to the print head 316 based on image data acquired through image processing by the print image processing unit 308. Based on the print signal, the print head 316 performs printing on the print medium by ejecting ink from the corresponding nozzle.

The operation panel 320 includes a display unit 321, an operation unit 322, and an operation panel Interface (IF) unit 323. The display unit 321 and the operation unit 322 are connected to the system bus 303 via an operation panel IF unit 323. Such a configuration allows, for example, outputting an image to be displayed on the display unit 321, or accepting an operation input to the operation unit 322.

Further, the control board 301 includes an audio output unit 325, a communication connection unit 327, an external Interface (IF) unit 331, a nonvolatile storage 333, and a wireless LAN module 334. The audio output unit 325 may, for example, convert audio data into a signal and output an audio message through the speaker 326 as an external sound source. A communication connection unit 327, connected to, for example, a communication network 328 or a telephone 329, may input and output audio data and encoded data. Here, the encoded data may be converted into and from image data by the image encoding unit 309.

The external IF unit 331 is configured as an external connection unit conforming to a predetermined standard such as the USB standard, for example, and an external device 332 such as a personal computer can be connected to the MFP 300 with the external IF unit 331. The nonvolatile storage device 333 for which a flash memory or the like is generally used can store work data, image data, and the like even when the MFP 300 is in an inactive state. The wireless LAN module 334 allows image data to be input from an external access point and output to the external access point. The power supply unit 340 supplies electric power necessary for realizing the functions thereof to the respective components of the MFP 300, such as the control board 301, the image reading unit 310, the printing unit 315, and the operation panel 320.

A part of the functions of MFP 300 will be exemplified below.

-scanning operation

The image information read by the CIS 30 and the CIS 31 of the image reading unit 310 is first subjected to image processing (such as shading correction) of reading the image correction unit 312. The image information is disposed in the RAM 305 as image data by the read image processing unit 307, and is then compressed and encoded in, for example, JPEG format by the image encoding unit 309. The encoded data is output to the external device 332 via the external IF unit 331. The scanning operation may acquire image data of image information read by the CIS 30 and the CIS 31 in the aforementioned manner.

-copy operation

The image information read by the CIS 30 and the CIS 31 of the image reading unit 310 is first subjected to image processing (such as shading correction) of reading the image correction unit 312. The image information is disposed as image data in the RAM 305 by the read image processing unit 307, and is then compressed and encoded into a JPEG format by the image encoding unit 309, and is temporarily stored in, for example, the RAM 305. The image data is sequentially sent to the print image processing unit 308 and converted into print data. The print data is output to the print head 316 via the print signal output unit 317, thereby performing printing on a print medium. In the copy operation, image information read by the CIS 30 and the CIS 31 may be printed on a printing medium and copied.

Facsimile transmission operation

The image information read by the CIS 30 and the CIS 31 of the image reading unit 310 is first subjected to image processing (such as shading correction) of reading the image correction unit 312. The image information is disposed as image data in the RAM 305 by the read image processing unit 307, then compressed and encoded into a Modified Read (MR) format by the image encoding unit 309, and temporarily stored in, for example, the RAM 305. The communication connection unit 327 transmits and receives a signal for starting facsimile communication, and then starts transmission of image data. The transmission of image data continues until it is completed, while image reading and associated encoding and temporary storage of image data are performed by the CIS 30 and the CIS 31. Accordingly, the facsimile transmission operation allows desired image data to be transmitted to a communication destination using facsimile.

Facsimile reception operation

For example, in response to reception from the communication network 328, the communication connection unit 327 transmits and receives a signal for starting facsimile communication, and then starts receiving image data. The image data is demodulated by the image encoding unit 309 and then disposed in the RAM 305. The image data is sequentially sent to the print image processing unit 308 and converted into print data. The print data is output to the print head 316 via the print signal output unit 317, thereby performing printing on a print medium. The facsimile reception operation allows arbitrary image data to be received from a communication destination by facsimile.

-a printing operation

The print job transmitted from the external device 332 and received via the external IF unit 331 is processed by the MPU 306, and is deployed as image data in the RAM 305 by the image encoding unit 309 based on instruction commands, parameters, and the like included in the job. The image data is sequentially sent to the print image processing unit 308 and converted into print data. The print data is output to the print head 316 via the print signal output unit 317, thereby performing printing on a print medium. In a printing operation, arbitrary image information can be printed on a printing medium and thus a printed material can be produced.

Fig. 3 is a block diagram illustrating a configuration example of a driving unit DR configured to perform image reading and document transfer. In other words, the concept of the driving unit DR includes the reading system driving unit 313 and the printing system driving unit 318 described above.

The driving unit DR includes a driving control unit 400, motor drivers 410 and 440, motors 420 and 450, and encoders 430 and 460. The motor driver 410, the motor 420, and the encoder 430 are provided corresponding to the image reading function, and may also be referred to as an image reading unit system motor driver 410, an image reading unit system motor 420, and an image reading unit system encoder 430, respectively. Further, the motor driver 440, the motor 450, and the encoder 460 are provided corresponding to the document conveying function, and may also be referred to as a document conveying system motor driver 440, a document conveying system motor 450, and a document conveying system encoder 460, respectively.

The drive control unit 400 includes a motor control unit 401, an encoder input unit 402, a servo control unit 406, and a position and speed detection unit 407 as components corresponding to the image reading function. They may also be referred to as an image reading unit system motor control unit 401, an image reading unit system encoder input unit 402, an image reading unit system servo control unit 406, and an image reading unit system position and speed detection unit 407, respectively.

Further, the drive control unit 400 includes a motor control unit 404, an encoder input unit 405, a servo control unit 408, and a position and speed detection unit 409 as components corresponding to the document conveying function. They may also be referred to as a document conveying system motor control unit 404, a document conveying system encoder input unit 405, a document conveying system servo control unit 408, and a document conveying system position and speed detection unit 409, respectively.

With such a configuration, the drive control unit 400 generates a Pulse Width Modulation (PWM) signal and controls the rotational speeds of the respective motors. For example, in image reading, the motor driver 410 supplies a current based on a PWM signal to the motor 420 to generate power (rotation). A DC motor is generally used as the motor 420, and power thereof is transmitted to components of the subsequent stage through a power transmission mechanism such as gears and belts. It is assumed that the encoder 430, which is a rotary encoder provided coaxially with the motor 420, detects the rotational direction and the rotational amount of the motor 420.

Similar to the image reading described above, each of the motor driver 440, the motor 450, and the encoder 460 realizes a corresponding function in document conveyance.

Further, servo control is performed for driving control of the motor 420 in image reading (the same applies to document conveyance). In other words, the encoder input unit 402 generates a signal based on the encoder signal as a detection signal from the encoder 430, whereby the position and speed detection unit 407 detects the rotation direction, the rotation amount, and the rotation speed of the motor 420. Here, the rotation amount of the motor 420 corresponds to the position of the moving target (here, CIS 30 or CIS 31).

The servo control unit 406 compares the result of the detection by the position and speed detection unit 407 with a target value, and generates a correction signal based on the comparison result to bring the control of the motor 420 into a desired mode (typically, feedback control is performed using PID control). The motor control unit 401 generates a PWM signal based on a signal from the servo control unit 406.

Fig. 4 is a block diagram illustrating a system configuration example of a detection system SY that can perform image reading. The detection system SY includes an image reading sensor 510 as the CIS 30 or the CIS 31, a CIS control unit 500 that performs driving control of the image reading sensor 510, and an Analog Front End (AFE) 520. The CIS control unit 500 includes an accumulation start signal generation unit 501, a CIS/AFE drive signal generation unit 502, and an image data input unit 503.

The accumulation start signal generation unit 501 generates an accumulation start signal (hereinafter referred to as "signal SH") for starting charge accumulation of the sensor 510, details of which will be described later. Based on the signal SH, the sensor 510 accumulates charges generated by photoelectric conversion, and acquires a set of pixel signals based on the charge accumulation amount as image signals. An image signal, which is an analog signal acquired by image reading with the sensor 510, is converted into a digital signal by analog-to-digital (AD) conversion by the AFE 520. The image data input unit 503 performs predetermined correction processing on the digital signal to generate image data, and the drive signal generation unit 502 generates drive signals for drive control of the sensor 510 and the AFE 520.

Fig. 5 is a timing chart for explaining an example of waveforms of control signals of the motor control unit (here, it is assumed that the motor control unit is the motor control unit 401, and the same is true for the motor control unit 404). Fig. 6 is a timing diagram for explaining an example of waveforms of an encoder signal of an encoder (here, it is assumed that the encoder is the encoder 430, and the same is true for the encoder 460).

As shown in fig. 5, the signals supplied to the motor driver 410 by the motor control unit 401 are represented as a signal ENABLE and a signal PHASE. The signal ENABLE is a signal for energizing the motor 420, which energizes the motor 420 at a high (H) level and suppresses energization at a low (L) level.

The signal PHASE is a PWM signal for setting the rotation direction and the current value of the motor 420. The PERIOD of the generally fixed signal PHASE may be set to, for example, 25 kilohertz (kHz). The duty cycle indicates the ratio of the duration of the H level of the signal PHASE to the PERIOD. For example, duty=50% indicates that the motor 420 is stopped. The duty >50% indicates that the motor 420 rotates in the positive direction (the scanning direction of the document (the direction from the start side to the distant side)), and the rotational speed of the motor 420 becomes higher as the duty approaches 100%. Further, the duty <50% indicates that the motor 420 rotates in the reverse direction (the returning direction of the document (the direction from the far side to the start side)), and the rotation speed of the motor 420 becomes higher as the duty approaches 0%.

As shown in fig. 6, the encoder 430 outputs two-phase signals, which are signals enc_a and enc_b. As can be seen from the rotation direction, the rotation direction is the positive direction (scanning direction) when the phase of the signal enc_a advances relative to the signal enc_b, and the rotation direction is the negative direction (returning direction) when the phase of the signal enc_a delays relative to the signal enc_b.

In other words, the encoder input unit 402 generates a signal based on the encoder signal as a detection signal from the encoder 430, whereby the position and speed detection unit 407 detects the rotation direction, the rotation amount (the position of the moving target), and the rotation speed of the motor 420. For example, after removing a signal having a relatively narrow pulse width, the encoder signal is input to the position and speed detecting unit 407 as signals enc_a and enc_b via the noise filter of the encoder input unit 402. The rotation amount is detected by measuring edges (rising edge) or falling edge (edge)) of the signals enc_a and enc_b, and the rotation speed is detected by measuring a time difference between the edges.

Fig. 7 illustrates logic in measuring the amount of rotation based on the encoder signal described above. In the present embodiment, the counter is measured to be incremented (+1) or decremented (-1) at the rising edge and the falling edge of one of the signals enc_a and enc_b based on the signal value of the other of the signals enc_a and enc_b.

For example, when the signal enc_b is at the L level at the rising edge of the signal enc_a, the counter is incremented (+1). Further, the same is true when the signal enc_b is at the H level at the falling edge of the signal enc_a, when the signal enc_a is at the H level at the rising edge of the signal enc_b, and when the signal enc_a is at the L level at the falling edge of the signal enc_b.

On the other hand, when the signal enc_b is at the H level at the rising edge of the signal enc_a, the counter is decremented (-1). Further, the same is true when the falling edge signal enc_b at the signal enc_a is at the L level, when the rising edge signal enc_a at the signal enc_b is at the L level, and when the falling edge signal enc_a at the signal enc_b is at the H level.

The rotational speed may be detected by calculating the inverse of the time difference between the edges. For example, the falling edge of the signal enc_b and the rising edge of the signal enc_a correspond to the rotation amount of one slit of the encoder 430. Thus, through T ₀ And T ₁ Representing the corresponding time (see fig. 6), the rotational speed may be expressed as 1/(T) ₁ -T ₀ )[Slit/sec]。

Fig. 8 is a timing chart indicating waveforms of each of signals in image reading by the CIS 30 as an example. In fig. 8, a signal SH for starting charge accumulation, a CLK signal for transmitting a signal corresponding to the charge accumulation amount, and a pixel signal VOUT based on the charge accumulation amount are illustrated as signals for performing drive control of the CIS 30. Further, a signal MCLK as a clock signal for driving the AFE 520 and a signal TSMP for sampling a signal corresponding to the charge accumulation amount are illustrated.

Here, it is assumed that the CIS 30 is formed by arranging a plurality of pixels in a matrix form, a signal SH is supplied to each line as an H-level pulse, and image reading is started at timing of supplying the H-level pulse of the signal SH corresponding to the first line. The signal CLK is supplied one-to-one to each pixel in the corresponding row, whereby the signal sampled by the pixel until then is output as the signal VOUT. The number of signals MCLK may vary depending on the configuration of AFE 520, where signals MCLK are provided to make the number of clocks of a single pixel four. Further, it is assumed that an H-level pulse is supplied as a signal TSMP to a single pixel, thereby determining the aforementioned sampling timing. In the AFE 520, sampling is performed when the signal TSMP is at the H level, and when it falls to the L level, that is, at the timing indicated by the arrow, the sampled signal is fixed (held).

In another embodiment, the CIS 30 may be configured to have a switchable resolution, in which case a signal for switching the resolution may be added.

Fig. 9 is a timing chart for explaining a mode of change in the rotational speed of the motor 420 in image reading, and fig. 10 is a timing chart indicating the rotational amount of the motor 420 (the position of the moving target) at that time.

In general, the rotation speed of the motor 420 may have a period of acceleration or deceleration during the period from the stopped state to the constant speed rotation state or during the period from the constant speed rotation state to the stopped state due to the inertial force of the motor 420. Thus, in the example of fig. 10, the motor 420 may have an acceleration state, a constant speed state, and a deceleration state. The motor 420 is controlled in an acceleration state such that the rotational speed is gradually increased to reach the target speed, in a constant speed state such that the rotational speed maintains the target speed, and in a deceleration state such that the rotational speed is gradually decreased to reach the target speed.

In the following description, the aforementioned acceleration state, constant speed state, and deceleration state may be simply denoted as acceleration, constant speed, and deceleration, respectively.

The aforementioned target speed may be preset by the servo control unit 406 (the servo control unit 408 in the case of the motor 450) described with reference to fig. 3 such that the target speed may be set to a constant value in a constant speed state and the target speed may be set to conform to predetermined acceleration and deceleration characteristics in an acceleration state and a deceleration state. The acceleration and deceleration characteristics may be a function of time or may be set by table values. Note that the acceleration and deceleration characteristics may be referred to as acceleration and deceleration curves or simply curves.

Here, the rotation amount of the motor 420 may be calculated by integration of the rotation speed. Thus, the characteristics in the acceleration state and the deceleration state can be calculated by the integration of the aforementioned function or table value. Alternatively, the calculation result of the integration may be stored in advance in a predetermined memory.

FIG. 11 is a diagram showing a time T in a line when the motor 420 is in an acceleration state in performing image reading ₁ To T _N (denoted as time T when they are not distinguished) ₁ Etc.) and the position Y of the moving object ₁ To Y _N (denoted as position Y when they are not distinguished) ₁ Etc.) and the relationship between the two. Similarly, fig. 12 illustrates a diagram when the motor 420 is in a decelerating state.

In fig. 11 (acceleration state), the position Y is indicated at equal intervals of a distance smaller than the acceleration distance ₁ Etc. and indicate and position Y ₁ Equal corresponding time T ₁ Etc. Here, position Y ₁ It is sufficient that the like is set to a known value in advance. Similarly, in fig. 12 (deceleration state), the position Y is illustrated with equal intervals of a distance smaller than the deceleration distance ₁ Etc. and indicate and position Y ₁ Equal corresponding time T ₁ Etc. In the drawing, the start time and position of acceleration and deceleration are set to the origin 0, and the time T ₁ Etc. are included in the acceleration period in fig. 11 and in the deceleration period in fig. 12.

Although details will be described later, position Y ₁ Waiting for sum time T ₁ Etc. are represented by acceleration characteristics or deceleration characteristics set in advance, and are represented by a plurality of positions Y equally spaced on the document by using the signal SH ₁ And the like to acquire pixel signals to perform image reading.

The acceleration characteristic (fig. 11) is represented by a polynomial of degree n of the function of the usage time, which in this example can be represented as follows.

y＝a _n t ⁿ +a _n-1 t ^n-1 +a _n-2 t ^n-2 +...+a ₁ t

(equation 1)

Here, a ₁ To a _n Is a coefficient and a is a since the diagram passes through the origin (0, 0) ₀ ＝0。

Although n in the foregoing is an integer equal to or greater than 2, n may be an integer of 3 or greater in order to increase the accuracy of the drive control, and the value of n may be changed as needed.

Use position Y ₁ Waiting for sum time T ₁ Etc., the aforementioned formula 1 may be expressed as the following formula 2, respectively.

Y ₁ ＝a _n T ₁ ⁿ +a _n-1 T ₁ ^n-1 +a _n-2 T ₁ ^n-2 +...+a ₁ T ₁

Y ₂ ＝a _n T ₂ ⁿ +a _n-1 T ₂ ^n-1 +a _n-2 T ₂ ^n-2 +...+a ₁ T ₂

.

.

.

Y _N ＝a _n T _N ⁿ +a _n-1 T _N ^n-1 +a _n-2 T _N ^n-2 +...+a ₁ T _N

(equation 2)

Here, coefficient a ₁ Isochronal position Y ₁ Etc. are known in the aforementioned equation 2. Therefore, the time T can be calculated based on the arithmetic processing of the higher-order equation ₁ Etc. The same is true for the deceleration characteristic (fig. 12), and the thus-specified operational expression can be used as the aforementioned acceleration and deceleration curves.

The determination of the position Y will be described with reference to fig. 13 ₁ Etc. Fig. 13 is a diagram illustrating a position detected by the encoder 430 (or 460) in association with a position where a pixel signal is acquired by the signal SH, in other words, fig. 13 is a diagram illustrating a relationship between the encoder position and the read position.

Here, the target to be read in a single operation (target to be read in a single driving operation of a plurality of pixels arranged in a matrix form, in other words, the H-level pulse of the signal SH in a single operation) is defined as a read line. For the read line, when the sub-scanning resolution is subscanReso [ dpi ], a single line is given by 1/subscanReso [ inch ]. For encoder position, a single slot is given by 1/EncReso [ slit ] when the encoder resolution is EncReso [ dpi ]. Furthermore, the distance of each line is given by EncReso/SubScanReso [ slit ].

Thus, the position Y of the read line ₁ Etc. may be represented as follows.

Y ₁ ＝1×EncReso/SubScanReso

Y ₂ ＝2×EncReso/SubScanReso

.

.

.

Y _N ＝N×EncReso/SubScanReso

Note that all of the aforementioned parameters may be real numbers, integers or fractions.

Fig. 14 is a diagram illustrating accumulation times in the CIS 30. In the determined position Y as described above ₁ Waiting for sum time T ₁ After that, the accumulation time in the CIS 30 is calculated. The accumulated time of each line passes the time T between the lines ₁ Etc., in other words, the accumulation time of the kth line can be calculated from T _k -T _k-1 Representation (where k=1 to N). For example, for the first row, T ₁ -0 is true (T) ₀ =0, because the diagram passes through the origin (0, 0)), and for the second row, T ₂ -T ₁ This is true.

In the manner described above, based on equally spaced locations Y on the document ₁ Waiting for the calculation time T ₁ Etc. and with time T ₁ And the like, and thus image reading can be appropriately performed even in the acceleration state and the deceleration state of the motor 420.

It is sufficient to set the value presented in fig. 14 for each line by the aforementioned calculation according to the accumulation start signal generating unit 501, wherein a timer using an internal clock can be generally used as the accumulation start signal generating unit 501. Alternatively, the values presented in fig. 14 may be calculated in advance based on known acceleration and deceleration characteristics. In another example, the values presented in fig. 14 may be pre-stored in a memory such as RAM 305 and read out line by line, which may be performed over time based on a timer.

Fig. 15 is a timing chart indicating the state of a signal SH that can be used for driving control of the CIS 30 (or 31) in the acceleration state. Similarly, fig. 16 illustrates a timing chart in a decelerating state.

In the acceleration state, the signal SH is generated so that the interval of the H-level pulse of each line becomes shorter, as shown in fig. 15. In the constant speed state, the signal SH is generated so that the interval of the H-level pulses is constant. In the decelerating state, the signal SH is generated so that the interval of the H-level pulse of each line becomes longer, as shown in fig. 16. Thus, the present embodiment allows the pixel signal to be acquired with an accuracy/amount similar to that of the constant speed state even in the acceleration state and the deceleration state, in other words, the image reading can be performed by accelerating or decelerating the CIS 30 (or 31). Such image reading in the acceleration state and the deceleration state may also be denoted as acceleration reading and deceleration reading, respectively, which may be collectively denoted as acceleration and deceleration reading.

Note that in this example, an H-level pulse of the signal SH is supplied even in the stopped state, and so-called blank reading of the signal is performed with the pulse, and the pixel signal acquired in the stopped state can be discarded. It is assumed that the signal SH in this aspect is supplied as an H-level pulse having a period similar to that in the constant speed state, but the present invention is not limited thereto.

Here, as has been described above, servo control is performed in the drive control of the motor 420 (or 450), and errors generally occur at the start of acceleration and the end of deceleration (when the rotational speed is relatively low). Therefore, it is also possible to generate the signal SH and start the acquisition of the pixel signal after the rotational speed has exceeded the reference in acceleration, and suppress the generation of the signal SH and terminate the acquisition of the pixel signal before the rotational speed falls below the reference in deceleration.

Further, as has been described above, the CIS 30 can read at the document platen in image reading and can read using the ADF. Therefore, when the image reading target reaches the edge of the document, it is also possible to start acceleration before the CIS 30 is located inside the frame of the document and perform deceleration after the CIS 30 is located outside the frame of the document so that the CIS 30 will stop.

Incidentally, depending on the image reading scheme, the acceleration reading and/or the deceleration reading may be omitted. For example, a sufficient acceleration distance of the CIS 30 can be ensured in reading at the document platen, and thus the acceleration reading can be omitted when the CIS 30 is accelerating movement. In the ADF reading, image reading is generally performed sequentially for a plurality of documents, and the second and subsequent documents are substantially in a constant speed state, so that the constant speed state is maintained until the image reading of the last document is completed, and thus the deceleration reading can be omitted.

Here, when the free space in the memory runs out during image reading, the motor 420 may be decelerated and stopped, and the CIS 30 is returned to the standby position, and then, when the free space has occurred in the memory, the motor 420 is accelerated again to resume image reading (switch back to processing). In such a case, the acceleration distance/deceleration distance can be ensured by recovering the image reading from the middle of the document, and thus acceleration and deceleration reading are not required.

Further, in ADF reading, in order to increase the speed of image reading of a plurality of documents, the inter-document distance may be set short. When the free space in the memory (including a case where the amount of the free space has fallen below the reference value) runs out during image reading using the ADF, so-called inter-page stop may be performed, which decelerates and stops the motor 420 after image reading of a certain document is completed, and accelerates the motor 420 again after the free space has occurred in the memory. In such a case, since it is difficult to secure a sufficient acceleration distance for image reading of the next document, the efficiency of image reading can be improved by performing the acceleration reading. On the other hand, for a document for which image acquisition has been completed, the motor 420 eventually decelerates in response to the free space in the memory running out, so there is no need to decelerate the reading.

Fig. 17 is a timing chart illustrating control contents at the time of starting image reading in a case where acceleration reading is not required for reading at the document platen. In the present example, it is assumed that acceleration of the motor 420 is completed before image reading starts, the rotational speed of the motor 420 is in a constant speed state of a substantially constant speed (within an error range of servo control), and the CIS 30 is driven according to the setting of the corresponding accumulation time. Thus, the image reading in the present example may be started in response to the position detected by the encoder 430 (or 460) having reached the start position of the image reading, and the image reading may be started in advance by, for example, 0.5 lines in consideration of the detection error, the control delay, and the like.

Reading using ADF generally does not require deceleration reading, and therefore it is sufficient to set the accumulation time to a value corresponding to a predetermined period when image reading of a single document is completed. Since acceleration and deceleration of the motor 420 are not performed when the free space of the memory is equal to or greater than the reference value, image reading can be started based on the result of detection by the encoder 430 while maintaining a constant speed state, similarly to reading at the document platen. Here, when the free space of the memory falls below the reference, the motor 420 is decelerated and stopped, and when the motor 420 accelerates again, the acceleration reading may be performed.

According to the present embodiment as has been described above, the motor driven in image reading is controlled based on predetermined acceleration and deceleration curves at the time of acceleration and deceleration. Therefore, the timing at which the rotation amount of the motor (the moving distance of the moving object) is in the equal interval can be calculated or specified by the arithmetic processing based on the acceleration and deceleration curves. Thus, the pixel signal can be acquired in the acceleration state and the deceleration state of the motor with accuracy/quality similar to that in the constant speed state, so that it is possible to achieve improvement in the quality of the image data and increase in the acquisition speed of the image data.

In this specification, the present embodiment has been described mainly focusing on the motor 420, and the contents of the embodiment are also applicable to the control of other motors (e.g., the motor 450). In other words, the content of the present embodiment can be applied to any component to be moved in image reading and any component to be driven in association therewith.

In the present specification, the present embodiment has also been described focusing on acceleration and deceleration of the motor 420, but the content is also applicable to a case where the rotational speed of the motor 420 varies according to a predetermined curve. In other words, the curve may be any curve as long as it can specify the amount of change when the rotational speed of the motor 420 (the moving speed of the moving object) is changed, and may be expressed as a driving speed curve, a rotational speed curve, a moving speed curve, or the like according to aspects.

< other examples >

Embodiments of the present invention may also be implemented by a computer of a system or apparatus including one or more circuits (e.g., application Specific Integrated Circuits (ASICs)) for performing the functions of one or more of the above embodiments, and by a method performed by a computer of a system or apparatus by, for example, reading and executing computer-executable instructions from a storage medium to perform the functions of one or more of the above embodiments, and/or controlling one or more circuits to perform the functions of one or more of the above embodiments, by, for example, reading and executing computer-executable instructions from a storage medium. The computer may include one or more processors (e.g., a Central Processing Unit (CPU), a Micro Processing Unit (MPU)), and may include a separate computer or a network of separate processors to read out and execute the computer-executable instructions. The computer-executable instructions may be provided to the computer, for example, from a network or a storage medium. The storage medium may include, for example, a hard disk, random Access Memory (RAM), read Only Memory (ROM), a storage device for a distributed computing system, an optical disk (such as a Compact Disk (CD), digital Versatile Disk (DVD), or blu-ray disc (BD) ^TM ) One or more of a flash memory device, memory card, etc.

The embodiments of the present invention can also be realized by a method in which software (program) that performs the functions of the above embodiments is supplied to a system or apparatus, a computer of the system or apparatus or a method in which a Central Processing Unit (CPU), a Micro Processing Unit (MPU), or the like reads out and executes the program, through a network or various storage mediums.

< appendix >

In the above description, the MFP 300 having a printing function using the inkjet printing method is described as an example, the printing function is not limited to the aforementioned aspect, and may be a function of manufacturing a color filter, an electronic device, an optical device, a microstructure, or the like using a predetermined printing method. Further, the MFP 300 may be any image reading apparatus having a scanning function as a main function, as long as the MFP 300 is configured to be able to perform the aforementioned acceleration and deceleration reading. Here, when the image reading apparatus is configured to exclusively employ reading at the document platen, it may also be referred to as a scanner. Further, MFP 300 may be another electronic device having a scanning function as a sub-function.

The term "printing" referred to herein should be interpreted broadly. Thus, aspects of "printing" include objects formed on a print medium that may or may not be meaningful information, such as characters or graphics, as well as objects that may or may not be visualized for human visual perception.

Similar to the aforementioned "printing", the term "print medium" should be interpreted broadly. Accordingly, the concept of "print medium" includes materials that can accept ink, such as cloth, plastic film, metal plate, glass, ceramics, resin, wood, leather, and the like, in addition to paper that is generally used.

Furthermore, the term "ink" should be interpreted broadly, similar to the aforementioned "printing". Thus, in addition to liquids applied to a print medium to form an image, mark, pattern, etc., the concept of "ink" may also include auxiliary liquids that may be applied for treatment of the print medium or treatment of the ink (e.g., curing or insolubilization of a colorant in the ink applied to the print medium).

Although the individual components in the foregoing embodiments are named in expressions based on their primary functions, the functions described in the embodiments may be secondary functions, and the naming is not strictly limited to these expressions. Furthermore, these expressions may be replaced by similar expressions. Similarly, the expression "unit" or "portion" may be replaced by "part", "member", "structure", "assembly", "means", or the like. Alternatively, they may be omitted.

While the invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims (12)

1. An image reading apparatus comprising:

an image reading unit configured to perform image reading;

a driving unit configured to move a target in image reading; and

a signal generation unit configured to generate a signal for driving the image reading unit,

the image reading apparatus is configured to acquire image data by the image reading unit performing image reading based on the signal generated by the signal generating unit in a case where the target is moved by the driving unit, wherein

The driving unit moves the target such that the target changes at a speed according to a predetermined driving speed profile, an

The signal generating unit generates a signal based on the driving speed profile at a timing at which the moving distance of the target is made equal to each other.

2. The image reading apparatus according to claim 1, wherein the timing at which the signal generating unit generates a signal is timing at which a moving distance of the target is made equal to an interval in both a period in which a moving speed of the target is changed and a period in which the target is in a constant speed state.

3. The image reading apparatus according to claim 2, wherein

The drive speed profile includes acceleration and deceleration profiles, and

the driving unit moves the target such that the target accelerates or decelerates according to the acceleration and deceleration profile.

4. The image reading apparatus according to claim 3, wherein the image reading unit starts image reading after acceleration of the target and before the target enters a constant speed state.

5. The image reading apparatus according to claim 3, wherein the image reading unit terminates image reading after the target decelerates and before the target is in a stopped state.

6. The image reading apparatus according to claim 3, wherein the acceleration and deceleration curves are n-degree polynomials, where n is an integer of 2 or more.

7. The image reading apparatus according to claim 3, wherein the acceleration and deceleration curves are n-degree polynomials, where n is an integer of 3 or more.

8. An image reading apparatus according to claim 3, wherein

The image reading device is a scanner and,

the image reading unit is an image sensor, and

the target is the image sensor.

9. The image reading apparatus according to claim 8, wherein the image reading unit suppresses start of image reading in acceleration of the target.

10. An image reading apparatus according to claim 3, wherein

The image reading apparatus is an ADF,

the image reading unit performs image reading on a document, and

the target is the document.

11. The image reading apparatus according to claim 10, wherein

The document is one of a plurality of documents, and

the image reading unit completes image reading of the plurality of documents while the driving unit maintains the target in a constant speed state.

12. A computer-readable storage medium storing a program configured to cause a computer to function as the respective units of the image reading apparatus according to any one of claims 1 to 11.