JP2004088416A - Image reading apparatus, image forming apparatus, control method for image reading apparatus, control method for image forming apparatus, program, and storage medium - Google Patents

Abstract

An image reading apparatus, an image forming apparatus, a control method of an image reading apparatus, and a control method capable of performing high-precision scanning in a vertical scanning direction even when a time related to paper conveyance is not proportional to a cycle of a motor pulse signal. Provided are a control method for an image forming apparatus, a program, and a storage medium.
An image forming apparatus includes an image forming unit that forms an image on paper, an LDV that measures the speed of a transport belt that transports the paper, and a speed synchronization that is synchronized with a speed signal output from the LDV. A scanner unit 100 having a synchronization circuit unit 109 for generating a signal and using the signal as a reference signal for the line CCD 102; and determining the magnitude of the gray level of data of each pixel based on reading of paper on which an image is formed by the scanner unit 100. A control device 10 is provided for performing image correction at the time of creating image data based on the result.
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image reading apparatus, an image forming apparatus, a method for controlling an image reading apparatus, a method for controlling an image forming apparatus, a program, and a storage medium. More specifically, horizontal scanning of a medium such as paper by a line-type photoelectric conversion unit. Reading apparatus that reads an image in the direction and moves the medium relative to the line-type photoelectric conversion unit in the vertical scanning direction to read the image, an image forming apparatus having the image reading apparatus, and a method of controlling the image reading apparatus And a control method for an image forming apparatus, a program, and a storage medium.
[0002]
[Prior art]
The configuration and operation of a conventional image reading apparatus will be described with reference to FIGS. 8A and 8B are configuration diagrams showing a configuration of an image reading apparatus according to a conventional example. FIG. 8A is a diagram of the configuration of the image reading device as viewed from the front, and FIG. It is. FIG. 9 is a block diagram showing functional blocks of the image reading apparatus having the configuration shown in FIG. In each of the drawings, components indicated by the same reference numerals are the same portions or the same portions.
[0003]
8A and 8B, reference numeral 100 denotes a scanner unit that reads an image from a medium to be read, 1000 denotes paper as the medium to be read, 70A, 70B, and 70C denote rollers, and 80 denotes rollers via rollers 70A, 70B, and 70C. This is a transport belt that is driven to circulate.
[0004]
In FIG. 9, reference numeral 10 denotes a control device including a CPU, a memory, a large-capacity storage device, a peripheral circuit, and the like, which are not shown, and controls each unit of the image reading device. Reference numeral 50 denotes a motor interface (I / F) circuit, and reference numeral 60 denotes a motor for driving the transport belt 80. The motor I / F circuit 50 generates a phase signal and the like for the motor 60, and supplies power to the motor 60 and the like. Further, 100 is a scanner unit, 1000 is paper as a reading target medium, 70A, 70B, and 70C are rollers, and 80 is a transport belt.
[0005]
The conveyance belt 80 in FIGS. 8 and 9 is wound around the rollers 70A, 70B, and 70C, and the power of the motor 60 is transmitted to the rollers 70B. As a result, the transport belt 80 performs the transport operation of the paper 1000 as the medium to be read in the direction of the arrow (vertical scanning direction) in FIG.
[0006]
In such a configuration, the conventional image reading apparatus performs the following operation. That is, the control device 10 in FIG. 9 activates the motor I / F circuit 50 and the scanner unit 100 and sends a motor pulse signal of a constant frequency to the motor I / F circuit 50. The frequency of the motor pulse signal is proportional to the rotation speed of the motor 60 and the number of rotations per fixed time. Upon receiving the motor pulse signal, the motor I / F circuit 50 responds to the frequency of the motor pulse signal. A phase signal is generated, and the motor 60 is rotated. By the rotation of the motor 60, power is transmitted to the roller 70B, and the transport belt 80 advances in the direction of the arrow (vertical scanning direction) in FIG. Transported in the direction of the arrow.
[0007]
On the other hand, the same motor pulse signal having a constant frequency sent to the motor I / F circuit 50 is also sent to the scanner unit 100. In the scanner unit 100, the motor pulse signal is synchronized (as it is or divided), and is used as a line reference signal of a line CCD, which is a line-type photoelectric conversion unit (not shown) in the scanner unit. At each rising edge of a line reference signal generated in synchronization with the motor pulse signal, the line CCD reads one line of image data in the horizontal scanning direction, and these image data are transferred to an image buffer (not shown) and stored. You. Then, the above operation is repeated while transporting the paper 1000 in the vertical scanning direction, and the above operation is performed for all the lines in the horizontal scanning direction, whereby image data for one sheet of the paper 1000 can be obtained.
[0008]
In this configuration, a signal synchronized with the motor pulse signal sent from the control device 10 and having a cycle proportional to the rotation cycle of the motor 60 is used as a line reference signal of the line CCD. Scanning of the paper 1000 in the vertical scanning direction can be performed. Therefore, for each rising edge of the line reference signal, the image reading operation of the medium to be read is achieved by collecting image data for all lines in the vertical scanning direction of the medium to be read and performing vertical scanning. Become.
[0009]
[Problems to be solved by the invention]
However, the above-described related art has the following problems. That is, the rotating shaft of the motor 60 and the rollers 70A, 70B, and 70C actually have eccentricity and the like, and do not necessarily take an ideal circular orbit but take a circular orbit with uneven rotation. In addition, an ideal power transmission mechanism cannot be achieved due to a mounting error of the roller with respect to the output shaft of the motor 60 or a secular change. Due to these rotation irregularities, the speed at which the transport belt 80 advances slightly fluctuates. An error occurs, and the time required for paper conveyance is not proportional to the cycle of the motor pulse signal.
[0010]
As long as an image such as a photograph is stored and reproduced as digital data by ordinary image reading, the above situation does not often cause a problem. However, when performing accurate image reading, or when reading image data at the pixel level to evaluate an image and performing image correction or the like based on the image data, high-precision scanning in the vertical scanning direction is performed. Therefore, there is a problem that an error caused by the above situation cannot be ignored.
[0011]
The present invention has been made in view of the above points, and provides an image reading apparatus capable of performing high-precision scanning in the vertical scanning direction even when the time required for paper conveyance is not proportional to the period of a motor pulse signal. It is an object to provide an image forming apparatus, an image reading apparatus control method, an image forming apparatus control method, a program, and a storage medium.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an image reading apparatus that reads an image in a horizontal scanning direction of a medium by a photoelectric conversion unit, and reads an image by moving the medium relative to the photoelectric conversion unit in a vertical scanning direction. , A speed measuring means for measuring a speed of a moving body for moving a medium, and a signal generating means for generating a speed synchronizing signal synchronized with a speed signal output from the speed measuring means and using the speed synchronizing signal as a reference signal of the photoelectric conversion means , And is applicable to image correction performed based on the determination of the density level of the data of each pixel based on reading of the medium.
[0013]
Further, the present invention includes an image reading device that reads an image of a medium in a horizontal scanning direction by a photoelectric conversion unit, and reads an image by moving the medium relative to the photoelectric conversion unit in a vertical scanning direction. In an image forming apparatus that forms an image with a recording head by relatively moving, a speed measuring unit that measures a speed of a moving body that moves a medium, and a speed synchronization unit that synchronizes with a speed signal output from the speed measuring unit. A signal generation unit that generates a signal and serves as a reference signal of the photoelectric conversion unit, and determines the magnitude of the density level of data of each pixel based on reading of the medium on which the image is formed by the image reading device, and Correction means for performing image correction at the time of image data creation based on the image data.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components denoted by the same reference numerals throughout the drawings indicate the same or corresponding portions.
[0015]
[First Embodiment]
The first embodiment of the present invention relates to an image reading device. FIG. 1 is a configuration diagram illustrating a configuration of an image reading apparatus according to a first embodiment. FIG. 1A is a diagram illustrating the configuration of the image reading apparatus as viewed from the front, and FIG. FIG. FIG. 2 is a block diagram showing functional blocks of the image reading apparatus having the configuration shown in FIG. The image reading apparatus includes a control device 10, a motor I / F circuit 50, a motor 60, rollers 70A, 70B, 70C, a conveyor belt 80, a scanner unit 100, and an LDV (laser Doppler velocimeter) 200. The CCD (see FIG. 4) reads an image of the medium to be read in the horizontal scanning direction, and reads the image by moving the medium to be read in the vertical scanning direction relative to the line CCD.
[0016]
1A, 1B and 2, the scanner unit 100 reads an image from a paper 1000 as a medium to be read. A transport belt 80 is wound around the rollers 70A, 70B, and 70C. The transport belt 80 is circulated through rollers 70A, 70B, and 70C. On the other hand, the control device 10 includes a CPU (not shown), a memory, a large-capacity storage device, a peripheral circuit, and the like, and performs control such that a speed signal output from the LDV 200 is used as a line reference signal of the line CCD. Further, the motor I / F circuit 50 generates a phase signal and the like for the motor 60, and supplies power to the motor 60 and the like. The motor 60 is a motor for driving the transport belt 80.
[0017]
The transport belt 80 in FIGS. 1A, 1B and 2 is wound around the rollers 70A, 70B, 70C as described above, and the power of the motor 60 is transmitted to the rollers 70B. By rotating the motor 60, the transport belt 80 performs the transport operation of the paper 1000 as the medium to be read in the direction of the arrow (vertical scanning direction) in FIG.
[0018]
In the first embodiment, as shown in FIGS. 1A, 1B and 2, an LDV (laser Doppler velocimeter) 200 as a velocity measuring means is provided in addition to the above configuration of the image reading apparatus. It is characterized by points. As shown in FIG. 1A, the LDV 200 is installed at a location facing the surface of the transport belt 80 to measure the transport speed of the surface of the transport belt 80. In this case, since the transport speed of the transport belt 80 is continuously measured by the LDV 200, as shown in FIG. 1B, the measurement position of the transport speed of the transport belt 80 in the LDV 200 does not interfere with the transport position of the paper 1000. The LDV 200 is installed at a position facing the end of the conveyor belt 80.
[0019]
The LDV 200 as the speed measuring means measures the speed of the moving body, and measures the speed of the moving body (the surface of the transport belt 80 in the first embodiment) by the operation shown in FIG. I do.
[0020]
FIG. 3 is a diagram showing the principle of the speed measurement of the LDV 200. In FIG. 3, a laser light source 201 emits laser light. The beam splitter 202 splits the laser light into two. The reflection mirror 203 reflects the laser light. The condenser lens 204 collects scattered light from the object to be measured. The light receiving sensor 205 includes a photoelectric conversion element or the like, and photoelectrically converts the scattered light collected by the condenser lens 204 into an electric signal. The amplifier 206 amplifies the output signal of the light receiving sensor 205. The bandpass filter 207 performs heterodyne detection to obtain a Doppler signal D. The signal processing circuit 208 performs signal processing described later and outputs a speed signal. The laser light source 201 to the signal processing circuit 208 are incorporated in the LDV 200. On the other hand, BL is an object to be measured, which is the transport belt 80 in the first embodiment.
[0021]
The principle of the speed measurement of the LDV 200 will be described with reference to FIG. 3. First, the laser light source 201 emits a laser beam LA. The emitted laser light LA is split into two in the beam splitter 202. One of the two laser beams L1 is transmitted through the beam splitter 202 and directly irradiates the measured object BL (80). On the other hand, the other half of the laser light L2 is reflected by the beam splitter 202, further reflected by the mirror 203, and applied to the measured object BL (80). As shown in FIG. 3, the laser beams L1 and L2 are respectively incident on the perpendicular to the object BL (80) at an angle of incidence θ and irradiate the object BL (80) with symmetrical orbits. I do.
[0022]
When the laser beams L1 and L2 are incident on the object BL (80) moving at a certain speed v, the object BL (80) scatters the laser lights L1 and L2, and the scattered light LB Emits. The scattered light LB reaches the light receiving sensor 205 through an optical system such as the condenser lens 204. The light receiving sensor 205 detects the scattered light LB and performs photoelectric conversion. Thus, the amplitude of the scattered light is converted into an electric signal and input to the amplifier 206. The amplifier 206 amplifies the amplitude of the electric signal picked up by the light receiving sensor 205 and outputs the amplified signal to the bandpass filter 207. In the subsequent band-pass filter 207, heterodyne detection is performed, and as a result, a Doppler signal D that is an analog signal is obtained.
[0023]
The Doppler signal D is obtained by electrically extracting a beat signal (beat) generated when the two laser beams L1 and L2 are scattered by the object to be measured BL (80) moving at the speed v. The frequency fD of the Doppler signal D is obtained from the velocity v of the DUT BL (80), the incident angle θ, and the wavelength λ of the laser light.
fD = 2v · sin θ / λ (1)
Is represented by the following equation. Therefore, by using the set incident angle θ, the wavelength λ of the laser beam, and the frequency fD observed from the waveform of the obtained Doppler signal D, it is possible to determine the speed of the object BL (80).
[0024]
On the other hand, in the LDV 200, the Doppler signal D is input to the signal processing circuit 208. The signal processing circuit 208 converts the above Doppler signal D having the frequency of fD into a pulse signal having the same frequency of fD, and outputs the pulse signal as a speed signal.
[0025]
That is, as shown in OUTPUT of FIG.
T (= 1 / fD) ・ ・ ・ ▲ 2 ▼
Pulse signal. This cycle T is calculated from the above equations (1) and (2).
T = λ / (2v · sin θ) (3)
Therefore, it is inversely proportional to the speed v of the measured object BL (80).
When the above equation (3) is modified, the following equation is obtained.
[0026]
T · v = λ / (2 · sin θ) (4)
The value obtained by multiplying the speed v and the period T has a dimension of length (distance), and λ / (2 · sin θ) on the right side of the above equation (4) is a constant value (constant distance L) determined by the design specification of the LDV 200. ).
[0027]
Therefore,
L≡λ / (2 · sin θ) ··· 5
In this case, the period T of the pulse signal indicates the time required for the device under test BL to travel the predetermined distance L. In other words, a rising edge of the pulse signal is generated every time the device under test BL advances the predetermined distance L. The size of the fixed distance L is, for example, L = 1.6 μm when the laser wavelength λ = 800 nm and sin θ = １ ／. That is, the rising edge of the pulse signal indicates a displacement every L = 1.6 μm, and a very precise displacement can be detected.
[0028]
In this way, the LDV 200 outputs a pulse signal capable of detecting a precise displacement as a speed signal in real time, in other words, a pulse signal indicating a time (period T) during which the measured object BL travels the predetermined distance L. Is output in real time as a speed signal.
[0029]
The principle of the LDV 200 has been described above. In the configuration of FIGS. 1 and 2 including the LDV 200, the image reading apparatus according to the first embodiment performs the following operation. That is, the control device 10 of the image reading apparatus in FIG. 2 activates the motor I / F circuit 50 and the scanner unit 100 and sends a motor pulse signal of a constant frequency to the motor I / F circuit 50. The frequency of the motor pulse signal is proportional to the rotation speed of the motor 60 and the number of rotations per fixed time. Upon receiving the motor pulse signal, the motor I / F circuit 50 responds to the frequency of the motor pulse signal. A phase signal is generated, and the motor 60 is rotated.
[0030]
By the rotation of the motor 60, power is transmitted to the roller 70B, the transport belt 80 advances in the direction of the arrow (vertical scanning direction) in FIG. 1, and the paper 1000 as the medium to be read adsorbed on the transport belt 80 is moved in FIG. Transported in the direction of the arrow. When the transport belt 80 advances in the direction of the arrow (vertical scanning direction) in FIG. 1, the LDV 200 outputs a speed signal in the form of a pulse signal based on the principle shown in FIG. In the first embodiment, the speed signal is input to the scanner unit 100.
[0031]
Next, FIG. 4 is a block diagram showing a configuration of the scanner unit 100, and FIG. 5 is a time chart showing an operation in the scanner unit 200. In FIG. 4, a lens 101 transmits reflected light from paper 1000 as a medium to be read. The line CCD 102 is a line-type photoelectric conversion unit, and performs charge accumulation, which will be described later, based on the reflected light of the paper 1000 irradiated with the light. The noise filter 103 removes noise of an output signal from the line CCD 102. The amplification circuit unit 104 amplifies an output signal from the noise filter 103 to a voltage suitable for A / D conversion in the next stage. The A / D conversion unit 105 performs A / D (analog / digital) conversion on the output of the preceding amplification circuit unit 104.
[0032]
The shading correction unit 106 performs shading correction on digital data output from the A / D conversion unit 105. The image buffer 107 stores the output pixel data after the shading correction. The timing circuit 108 controls the operation timing of each block (the line CCD 102, the A / D conversion unit 105, and the shading correction unit 106) in the scanner unit. The synchronization circuit unit 109 receives a speed signal from the LDV 200 and outputs a line reference signal (= speed synchronization signal) to the line CCD 102. The light source 110 is configured by a fluorescent lamp, a light, or the like that irradiates light to the paper 1000 as a reading target medium.
[0033]
The operation of the scanner unit 100 having such a configuration will be described with reference to FIGS.
[0034]
In FIG. 4, a speed signal generated by the LDV 200 is input to the synchronization circuit unit 109 in the scanner unit 100. The synchronization circuit unit 109 converts the speed signal into a signal waveform suitable for use as a line reference signal by, for example, dividing the input speed signal to generate a speed synchronization signal. That is, the synchronization circuit unit 109 performs processing such as dividing or multiplying the input speed signal in order to obtain a time interval required as a line reference signal. However, the processing may be such that the speed signal is multiplied by 1 without dividing or multiplying the speed signal, or the speed signal itself may be used as the speed synchronization signal by omitting the synchronization circuit unit 109. In short, it is sufficient that the speed synchronization signal is a signal synchronized with the speed signal.
[0035]
As described above, the interval required to generate the index signal (speed synchronization signal) does not always coincide with the constant distance L measured by the LDV 200, so that the synchronization circuit 109 mainly divides or multiplies the speed signal. Is performed. Further, it is more preferable for the synchronization circuit unit 109 to be able to perform arbitrary frequency division or multiplication on the speed signal. The speed synchronization signal is input to the line CCD 102 as a line reference signal of the line CCD 102 and is also input to the timing circuit 108. The timing circuit 108 generates operation timing signals and the like for the A / D converter 105 and the shading corrector 106 based on the speed synchronization signal, and adjusts overall timing in the scanner unit 100.
[0036]
In such a configuration, when the paper 1000 as the medium to be read is conveyed below the scanner unit 100 by the conveyance belt 80, the light source 110 irradiates the light to the paper 1000 as the medium to be read. One line of the reflected light from the paper 1000 in the horizontal scanning direction is incident on the line CCD 102. The line CCD 102 starts accumulating electric charge corresponding to the amount of light in each pixel in a charge accumulating unit (not shown) in the line CCD 102 at each rising edge of the speed synchronization signal input as the line reference signal.
[0037]
The state of charge accumulation will be described with reference to FIG. 5. When a certain time (= charge accumulation time) elapses from the start of charge accumulation in the charge accumulation unit in the line CCD 102, a shutter (not shown) is closed thereafter. Avoid accumulation of charge. The time (charge holding time) from the end of the charge accumulation to the rising edge of the speed synchronization signal input as the next line reference signal, the sensor accumulation line in the line CCD 102 is a charge corresponding to the light amount in each pixel. Hold the quantity.
[0038]
Then, if a rising edge of the speed synchronization signal input as the next line reference signal occurs, the electric charge accumulated as the pixel data of the first line is sent to the sensor output line register. As a result, for each rising edge of the line reference signal, the line CCD 102 reads one line of image data in the horizontal scanning direction. Then, at the same time, accumulation of charges as pixel data of the next second line is started.
[0039]
While the charge of the second line is being accumulated and held, the pixel data of the first line temporarily stored in the sensor output line register is the output generated by the timing circuit 108 input to the sensor output line register. The pixels are sequentially read out by the clock for use, such as one pixel for each pixel and two pixels for one pixel. Then, before the rising edge of the next line reference signal, the reading of all the pixels on the first line is completed.
[0040]
In the actual line CCD 102, various kinds of read control such as idle reading may be performed, but they are simplified for explanation. However, such control is included in the scope of the present invention.
[0041]
.., 1 of the pixels 1 on the first line read in this way are sequentially input to the noise filter 103 shown in FIG. Input to the unit 104. The amplifier circuit 104 amplifies the pixel data to an appropriate voltage for A / D conversion in the next stage and inputs the amplified voltage to the A / D converter 105. The A / D converter 105 converts analog data corresponding to the amount of charge stored as pixel data of each pixel into digital data. The converted digital data is subjected to shading correction by the shading correction unit 106 for each pixel, and digital data (output pixel data) corresponding to each pixel after the shading correction is stored in the image buffer 107. Thus, the image reading operation of the scanner unit 100 for one line of the image is completed.
[0042]
In FIG. 5, while the pixel data of the first line is being read from the sensor output line register of the line CCD 102, the charge storage section in the line CCD 102 starts to store the charge as the pixel data of the second line. Then, similarly to the first line, accumulation and holding of electric charge as pixel data for one line are performed for the second line. Further, if a rising edge of the speed synchronization signal input as the next line reference signal occurs, the electric charge accumulated as the pixel data of the second line is sent to the sensor output line register. At the same time, accumulation of charges as pixel data of the next third line is started. Similarly, the second line is sequentially read out by the output clock in the same manner as one pixel for each pixel and two pixels for two, and these pixel data are processed in the same manner as each pixel data on the first line. Are stored in the image buffer 107.
[0043]
The above-described image reading operation by the scanner unit 100 is performed while the paper 1000 is transported in the vertical scanning direction by the transport belt 80. Therefore, by reading pixels of all lines in the horizontal scanning direction in the vertical scanning direction, image reading of one sheet of paper 1000 is achieved. Therefore, the reading operation following the first line and the second line is repeated up to the n-th line which is the last line in the horizontal scanning direction for one sheet of the paper 1000 while conveying the paper 1000 in the vertical scanning direction. The image reading is completed by performing the operation for all the lines in the horizontal scanning direction, and storing the output pixel data in the image buffer 107.
[0044]
That is, by such an operation, image data for one sheet of paper 1000 can be obtained, and as described above, every rising edge of the line reference signal, the entire vertical scanning direction of the medium to be read (paper 1000) can be obtained. The image reading operation of the medium to be read is achieved by collecting image data for the line and performing vertical scanning.
[0045]
In the first embodiment, the LDV 200 measures the transport speed of the transport belt 80 as the transport belt 80 advances in the direction of the arrow (vertical scanning direction) in FIG. Then, a speed signal is output in the form of a pulse signal based on the speed measurement (step S1), and the speed signal is input to the synchronization circuit unit 109 of the scanner unit 100 (step S2). Then, the synchronizing circuit 109 creates a speed synchronizing signal synchronized with the speed signal (step S3), inputs the speed synchronizing signal to the line CCD 102 as a line reference signal of the line CCD 102 (step S4), and inputs it to the timing circuit 108. Is a reference for the operation of the entire scanner unit 100.
[0046]
This speed synchronization signal is generated at a frequency proportional to the transport speed of the transport belt 80 detected by the LDV 200 (a period inversely proportional to the transport speed of the transport belt 80). Therefore, even if the speed of the transport belt 80 fluctuates, the time during which the speed synchronizing signal is generated is adjusted correspondingly, so that the speed synchronizing signal is generated in a form that corrects the speed fluctuation. The line reference signal is output in such a manner that the speed fluctuation of the belt 80 is corrected.
[0047]
In other words, it can be said that the cycle of the speed synchronization signal (= line reference signal) indicates the time required for the transport belt 80 to travel a predetermined distance in the vertical scanning direction according to the above equation (5). That is, assuming that the cycle of the speed signal is T and the speed signal itself is the speed synchronization signal, the speed synchronization signal (= line reference signal) is the time (= cycle) in which the transport belt 80 travels the distance L in the vertical scanning direction. T) is faithfully output every T). For example, if the laser wavelength λ = 800 nm and sin θ = 1/4, a line reference signal will be emitted at L = 1.6 μm. It is needless to say that a similar effect can be obtained as long as the speed signal itself is not synchronized with the speed synchronization signal as long as the speed signal is synchronized.
[0048]
This image reading apparatus is mounted on an image forming apparatus according to a second embodiment described later, and is applicable to image correction performed based on the determination of the density level of data of each pixel based on paper reading. It is.
[0049]
As described above, according to the first embodiment, the speed of the transport belt 80 that transports the paper as the medium to be read is measured, and the speed synchronization signal synchronized with the speed signal based on the measurement is output to the line CCD 102. , And scans all the lines in the horizontal scanning direction in the vertical scanning direction with a pulse signal having a cycle proportional to the time required for actual paper conveyance. This makes it possible to execute the accumulation operation of the line CCD 102, which is a scan in the horizontal scanning direction for one line at fixed distances and in very fine units, and for each very precise displacement in the vertical scanning direction. Image reading can be performed. Therefore, even when the time required for paper conveyance is not proportional to the cycle of the motor pulse signal, it is possible to provide an image reading apparatus capable of performing high-precision scanning in the vertical scanning direction. is there.
[0050]
[Second embodiment]
The second embodiment of the present invention relates to an image forming apparatus. FIG. 6 is a configuration diagram illustrating a configuration of an image forming apparatus according to the second embodiment. FIG. 6A is a diagram illustrating the configuration of the image forming apparatus as viewed from the front, and FIG. FIG. FIG. 7 is a block diagram showing functional blocks of the image forming apparatus having the configuration of FIG. The image forming apparatus includes a control device 10, a motor I / F circuit 50, a motor 60, rollers 70A, 70B, 70C, a conveyor belt 80, a scanner unit 100, an LDV (laser Doppler velocimeter) 200, and an image forming unit 300. The image forming apparatus 300 is provided with a recording medium for forming an image by relatively moving the image forming target medium.
[0051]
6A, FIG. 6B and FIG. 7, the scanner unit 100 reads an image from a paper 1000 as an image forming target medium. A transport belt 80 is wound around the rollers 70A, 70B, and 70C. The transport belt 80 is circulated through rollers 70A, 70B, and 70C. On the other hand, the control device 10 includes a CPU (not shown), a memory, a large-capacity storage device, a peripheral circuit, and the like, and controls the speed signal output from the LDV 200 to be a line reference signal of a line CCD, and controls each pixel. Is determined based on the result of the determination, and image data is corrected based on the determination result. Further, the motor I / F circuit 50 generates a phase signal and the like for the motor 60, and supplies power to the motor 60 and the like. The motor 60 is a motor for driving the transport belt 80.
[0052]
The transport belt 80 in FIGS. 6A, 6B and 7 is wound around the rollers 70A, 70B, 70C, and the power of the motor 60 is transmitted to the rollers 70B. By rotating the motor 60, the transport belt 80 performs the transport operation of the paper 1000 as the image forming target medium in the direction of the arrow (vertical scanning direction) in FIG.
[0053]
Next, in FIG. 6A, FIG. 6B and FIG. 7, the image forming unit 300 is a unit including a recording head such as an ink jet head for forming an image based on an image read by the scanner unit 100. The recording heads 300y, 300m, 300c, and 300k are provided for each color of magenta, cyan, and black. The recording heads 300y, 300m, 300c, and 300k are recording heads that are formed in an elongated shape in a horizontal scanning direction that is a direction perpendicular to the transport direction of the paper 1000 as an image forming target medium. It is possible to perform one-color image formation for one line at a time. In these print heads 300y, 300m, 300c, and 300k, a print head control board (not shown) is integrally formed with the print head for each color, and a head for image formation faces the transport belt 80. The arrangement is arranged.
[0054]
In controlling image formation in the entire image forming unit 300 and the recording heads 300y, 300m, 300c, and 300k in the image forming unit 300, data is transferred from the control device 10 to the image forming unit 300, and a vertical scanning direction timing signal is separately provided. To control the image formation.
[0055]
In the second embodiment, as shown in FIGS. 6A, 6B, and 7, an LDV (laser Doppler velocimeter) 200 as a velocity measuring unit is provided in addition to the above-described configuration of the image forming apparatus. It is characterized by points. As shown in FIG. 6A, the LDV 200 is installed at a location facing the surface of the transport belt 80 to measure the transport speed of the surface of the transport belt 80. In this case, since the transport speed of the transport belt 80 is continuously measured by the LDV 200, as shown in FIG. 6B, the measurement position of the transport speed of the transport belt 80 in the LDV 200 does not interfere with the transport position of the paper 1000. The LDV 200 is installed at a position facing the end of the conveyor belt 80.
[0056]
The LDV 200 as the speed measuring means measures the transport speed of the moving body (the surface of the transport belt 80 in the second embodiment) according to the principle and operation shown in FIG. 3 described in the first embodiment. . Then, the LDV 200 outputs the speed signal in the form of a pulse signal as in the first embodiment. That is, the LDV 200 outputs a pulse signal capable of detecting a precise displacement as a speed signal in real time, in other words, a pulse signal indicating a time (period T) during which the moving body travels a predetermined distance L as a speed signal. Output to
[0057]
In the configurations of FIGS. 6A, 6B and 7 including the LDV 200 having the above configuration, the image forming apparatus according to the second embodiment performs the following operation. That is, the control device 10 of the image forming apparatus in FIG. 7 activates the motor I / F circuit 50 and the scanner unit 100 and sends a motor pulse signal of a constant frequency to the motor I / F circuit 50. The frequency of the motor pulse signal is proportional to the rotation speed of the motor 60 and the number of rotations per fixed time. Upon receiving the motor pulse signal, the motor I / F circuit 50 responds to the frequency of the motor pulse signal. A phase signal is generated, and the motor 60 is rotated.
[0058]
When the motor 60 rotates, the power is transmitted to the roller 70B, and the transport belt 80 advances in the direction of the arrow (vertical scanning direction) in FIG. 6 is conveyed in the direction of the arrow. When the transport belt 80 advances in the direction of the arrow (vertical scanning direction) in FIG. 6, the LDV 200 outputs a speed signal in the form of a pulse signal. Therefore, in the second embodiment, the speed signal is input to the scanner unit 100, and the speed signal is input to the image forming unit 300 as a vertical scanning direction timing signal of the image forming unit 300.
[0059]
In such a configuration, in the second embodiment, while the data is transferred from the control device 10 to the image forming unit 300, the recording head in the image forming unit 300 An image is formed on the paper 1000 by a method such as discharging ink at 300y, 300m, 3000c, and 300k.
[0060]
In the image formation in the horizontal scanning direction, since the recording heads 300y, 300m, 3000c, and 300k formed in the horizontal scanning direction are used, one color of one line in the horizontal scanning direction is used. Image formation can be performed at once. On the other hand, for image formation in the vertical scanning direction, since a speed signal from the LDV 200 is input as a timing signal in the vertical scanning direction of the image forming unit 300, a speed synchronizing signal is generated from the speed signal as in the case of the scanner unit 100. Then, based on the speed synchronization signal, it is assumed that ink is discharged from the recording heads 300y, 300m, 3000c, and 300k. By performing such control, the image formation in the vertical scanning direction can also be performed at regular intervals detected by the LDV 200, such as ink ejection, so that extremely precise image formation control can be performed.
[0061]
By the way, among the recording heads, in the recording head of the ink jet system, there are problems such as a change in the characteristics of nozzles of each pixel of the recording head, a problem of non-ejection of ink due to disconnection or clogging of nozzles of each pixel of the recording head, and the like. The ink ejection direction is bent in the horizontal scanning direction or the vertical scanning direction, and the ink is ejected at a position different from the assumed position (ink landing shifted from the assumed position in the horizontal direction). There is a case where a problem such as ink landing vertically shifted) occurs.
[0062]
Therefore, in the present image forming apparatus, the output image is corrected by correcting the ink ejection and the like in consideration of the above problem. However, even recording heads other than the ink-jet type have their characteristics, so correction is often performed. By performing such correction, the image quality of the image forming apparatus is often improved. Therefore, in the second embodiment, the image correction is performed by reading the paper 1000 on which the image has been formed by the scanner unit 100 again, reading the image in the image buffer 107, and analyzing the content thereof.
[0063]
Hereinafter, the image correction will be described. In the above-described manner, the paper 1000 on which image formation has been completed in the image forming unit 300 flows downstream on the transport belt 80, and if the paper 1000 is transported below the scanner unit 100, the scanner unit 100 reads the image according to the procedure described in the first embodiment.
[0064]
As for the image reading operation, the LDV 200 outputs a speed signal in the form of a pulse signal and inputs the speed signal to the scanner unit 100 in the same manner as in the first embodiment. Perform the operation. Since the line reference signal is output in a form including the correction of the speed fluctuation, and the line reference signal is generated each time the transport belt 80 advances a predetermined distance in the vertical scanning direction, the line reference signal is output at every constant distance and very finely. It is possible to execute the accumulation operation of the line CCD 102, which is a scan in the horizontal scanning direction for one line in units. As a result, it is possible to execute image reading for each very precise displacement in the vertical scanning direction. The image data read by the above method is stored in the image buffer 107.
[0065]
In the second embodiment, as shown in the schematic flowchart of FIG. 11, the control device 10 reads data from the image buffer 107 and determines the density of all pixel data for each recording head 300y, 300m, 3000c, and 300k. The analysis is performed (step S11). As a method of this grayscale analysis, for example, when an image is formed by the image forming unit 300 upstream of the scanner unit 100, for a certain area of all pixels in a certain horizontal scanning direction and a certain area of several lines in a vertical scanning direction, There is a method of performing an image forming operation by setting the density of each pixel to a constant density and performing a density analysis. In the recording head of the ink jet system, the above-mentioned constant density setting can be realized by controlling the ejection amount of the ink to be constant in the above-mentioned constant area.
[0066]
Depending on the state of the recording heads 300y, 300m, 3000c, and 300k, the image formed on the paper 1000 often has shading. Therefore, the control device 10 reads the data of each pixel from the image buffer 107 and reads the data. The shade level of the data is determined. Then, by reading the level value of the gray level of the read data and judging the magnitude (step S12), the characteristic change of the nozzle of each pixel of the recording head of each color, the ink in the nozzle of the nozzle of each pixel of the recording head are determined. It is possible to detect ejection, horizontal deflection and vertical deflection (step S13).
[0067]
By performing the detection as described above, when the control device 10 generates the next and subsequent image data based on the determination of the level value of the gray level of the image data, each of the recording heads 300y, 300m, 3000c, and 300k The shading of each pixel data is compensated by shading correction, the non-ejection of ink of the nozzle of the recording head is compensated by another nozzle or a recording head of another color, and horizontal and vertical deviations are caused between neighboring pixels. The image is corrected by performing control to complement the adjustment.
[0068]
It should be noted that any image correction method, such as whether the above-described image correction is performed during a normal image forming operation or in a special mode, may be any method and is within the scope of the present invention.
[0069]
As described above, according to the second embodiment, by judging the magnitude of the gray level of the image data of each pixel based on the image reading of the paper, and performing the image correction based on the judgment result, more beautiful. An image forming apparatus capable of forming a precise image can be provided, which is very useful.
[0070]
Further, in the method of correcting the image by reading the image after forming the image, precise image reading accuracy is required for the width of the pixel. However, in the second embodiment, the output from the LDV 200 is speeded up. Since the signal is a signal and the speed synchronization signal generated based on the speed signal is used as the line reference signal of the line CCD 102, the accuracy of image reading is very high and very effective.
[0071]
Further, in an image forming apparatus having an image reading function and an image forming function, by performing scanning in a vertical scanning direction with a signal having a cycle proportional to the time required for actual paper conveyance, vertical scanning for image formation is performed. The accuracy and the accuracy of vertical scanning for image reading can be matched with high accuracy, and control very suitable for an image forming apparatus that performs image correction as described above can be realized.
[0072]
[Other embodiments]
In the above embodiment, the preferred embodiment of the present invention has been described. However, within the scope not departing from the technical idea of the present invention, the configuration, control, and combination of each part of the image reading apparatus and the image forming apparatus are described. It goes without saying that various changes can be made.
[0073]
In addition, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the technical idea of the present invention. For example, the scanning method of the vertical scanning method is not particularly limited to a specific method. Needless to say, a conveying belt may not be used and the scanner unit may be moved. Further, the speed measuring means is not limited to the LDV, and it is a matter of course that an alternative speed measuring means only needs to output a speed signal.
[0074]
Another object of the present invention is to provide a storage medium storing program codes of software for realizing the functions of the embodiments to a system or an apparatus, and a computer (or a CPU or an MPU or the like) of the system or apparatus to store the storage medium. It is also achieved by reading and executing the program code stored in the.
[0075]
In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.
[0076]
Examples of a storage medium for supplying the program code include a floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, and DVD. -RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM, and the like can be used.
[0077]
When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also an OS (Operating System) running on the computer based on the instruction of the program code. This also includes a case where some or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing.
[0078]
Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. This also includes the case where the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.
[0079]
【The invention's effect】
As described above in detail, according to the present invention, the speed of a moving object that moves a medium is measured, and a speed synchronization signal synchronized with the speed signal based on the measurement is used as a reference signal of the photoelectric conversion unit, and the actual medium is measured. In order to perform scanning in the vertical scanning direction with a signal having a period proportional to the time related to the movement of the medium, even if the time related to the movement of the medium is not proportional to the cycle of the signal for driving the moving body that moves the medium, It is possible to provide an image reading device that enables high-precision scanning in the vertical scanning direction.
[0080]
In addition, an image forming apparatus that can perform more beautiful and precise image formation by judging the magnitude of the gray level of the data of each pixel based on the reading of the medium and performing image correction when creating image data based on the judgment result. Can be provided.
[0081]
Further, in the image forming apparatus provided with the image reading device, by performing scanning in the vertical scanning direction with a signal having a cycle proportional to the time required for actual movement of the medium as described above, vertical scanning for image formation is performed. And the accuracy of vertical scanning for image reading can be made to match with high accuracy, and control very suitable for an image forming apparatus that corrects an image based on the magnitude of the gray level can be realized.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of an image reading apparatus according to a first embodiment of the present invention, where (a) is a view from the front and (b) is a view from the right side.
FIG. 2 is a block diagram illustrating functional blocks of the image reading apparatus of FIG. 1;
FIG. 3 is a diagram illustrating a principle of speed measurement of an LDV of the image reading apparatus of FIG. 1;
FIG. 4 is a block diagram illustrating a configuration of a scanner unit of the image reading apparatus of FIG. 1;
FIG. 5 is a time chart showing an operation in the scanner unit.
FIGS. 6A and 6B are configuration diagrams illustrating a configuration of an image forming apparatus according to a second embodiment of the present invention, where FIG. 6A is a diagram viewed from the front and FIG. 6B is a diagram viewed from the right side.
FIG. 7 is a block diagram illustrating functional blocks of the image forming apparatus of FIG. 6;
8A and 8B are configuration diagrams illustrating a configuration of an image reading apparatus according to a conventional example, in which FIG. 8A is a front view, and FIG. 8B is a right side view.
FIG. 9 is a block diagram illustrating functional blocks of the image reading apparatus of FIG. 8;
FIG. 10 is a schematic flowchart illustrating a speed synchronization signal creation process of the image reading apparatus of FIG. 1;
FIG. 11 is a schematic flowchart illustrating an image correction process of the image forming apparatus of FIG. 6;
[Explanation of symbols]
10 control device (correction means)
50 Motor I / F circuit
60 motor
80 Conveyor belt (moving body)
100 Scanner unit
102 line CCD (photoelectric conversion means)
106 Shading correction unit
107 Image buffer
109 Synchronous circuit section (signal generation means)
200 LDV (speed measurement means)
300 Image forming unit
300y yellow recording head
300m magenta recording head
300c cyan recording head
300k black recording head

Claims (11)

In an image reading apparatus that reads an image in a horizontal scanning direction of a medium by a photoelectric conversion unit and reads an image by moving the medium relative to the photoelectric conversion unit in a vertical scanning direction,
Speed measuring means for measuring the speed of a moving body for moving a medium, and signal generating means for generating a speed synchronization signal synchronized with a speed signal output from the speed measuring means and serving as a reference signal for the photoelectric conversion means. An image reading apparatus, wherein the image reading apparatus is applicable to image correction that is performed based on a determination of the magnitude of a gray level of data of each pixel based on reading of the medium. The signal generation unit generates a speed synchronization signal having a period proportional to the time required for movement of the medium by the moving body, and the photoelectric conversion unit performs the horizontal scanning in the vertical scanning direction using the speed synchronization signal as a reference signal. 2. The image reading apparatus according to claim 1, wherein image reading for each line in the direction is performed. An image reading device that reads an image in a horizontal scanning direction of a medium by a photoelectric conversion unit and reads an image by relatively moving the medium in a vertical scanning direction with respect to the photoelectric conversion unit, and relatively moves the medium. In an image forming apparatus that forms an image by a recording head,
Speed measuring means for measuring the speed of the moving body that moves the medium, signal generating means for generating a speed synchronization signal synchronized with a speed signal output from the speed measuring means and serving as a reference signal for the photoelectric conversion means, Correction means for judging the magnitude of the gray level of the data of each pixel based on reading of the medium on which the image has been formed by the image reading device, and performing image correction at the time of creating the image data based on the judgment result. Image forming apparatus. The signal generation unit generates a speed synchronization signal having a period proportional to the time required for movement of the medium by the moving body, and the photoelectric conversion unit performs the horizontal scanning in the vertical scanning direction using the speed synchronization signal as a reference signal. 4. The image forming apparatus according to claim 3, wherein image reading for each line in the direction is performed. The recording head includes an ink jet recording head, and the correction unit compensates for the density of data of each pixel by shading correction for each of the recording heads, or corrects a non-ejection of ink of a nozzle of the recording head by another nozzle. The image forming apparatus according to claim 3, wherein the image correction is performed by a process of compensating for the deviation of the ink landing position of the recording head or a process of compensating for the deviation of the ink landing position of the recording head. In the control method of an image reading device that reads an image in a horizontal scanning direction of a medium by a photoelectric conversion unit and reads an image by moving the medium relative to the photoelectric conversion unit in a vertical scanning direction,
A speed measurement step of measuring the speed of the moving body that moves the medium, and a signal generation step of generating a speed synchronization signal synchronized with the speed signal output from the speed measurement step and using the speed synchronization signal as a reference signal of the photoelectric conversion unit. A control method of the image reading apparatus, wherein the control method is applicable to image correction performed based on a determination of a density level of data of each pixel based on reading of the medium. An image reading device for reading an image in a horizontal scanning direction of a medium by a photoelectric conversion unit and reading an image by moving the medium relative to the photoelectric conversion unit in a vertical scanning direction, and forming an image on the medium by a recording head. And a method of controlling an image forming apparatus for forming an image by relatively moving a medium,
A speed measurement step of measuring the speed of the moving body that moves the medium, and a signal generation step of generating a speed synchronization signal synchronized with a speed signal output from the speed measurement step and using the signal as a reference signal of the photoelectric conversion unit, An image forming apparatus comprising: a judgment step of judging a density level of data of each pixel based on reading of a medium by the image reading device, and performing image correction when creating image data based on the judgment result. Control method. In a program applied to an image reading apparatus that reads an image in a horizontal scanning direction of a medium by a photoelectric conversion unit and reads an image by moving the medium relative to the photoelectric conversion unit in a vertical scanning direction,
A program for causing a computer to measure a speed of a moving object that moves a medium, and a function of generating a speed synchronization signal synchronized with a speed signal based on the speed measurement and using the signal as a reference signal of the photoelectric conversion unit. A program that can be applied to image correction performed based on the determination of the density level of data of each pixel based on reading of the medium. An image reading device that reads an image in a horizontal scanning direction of a medium by a photoelectric conversion unit and reads an image by moving the medium relatively in a vertical scanning direction with respect to the photoelectric conversion unit, and forms an image on the medium by a recording head. And a program applied to an image forming apparatus that forms an image by relatively moving a medium,
A function of measuring a speed of a moving body that moves a medium to a computer, a function of generating a speed synchronization signal synchronized with a speed signal based on the speed measurement and using the signal as a reference signal of the photoelectric conversion unit, and the image reading device A program for judging the magnitude of the gray level of the data of each pixel based on the reading of the medium by the computer, and performing the image correction at the time of creating the image data based on the judgment result. A computer storing a program for executing a control method of an image reading apparatus for reading an image in a vertical scanning direction with respect to the photoelectric conversion unit while reading an image of the medium in a horizontal scanning direction by a photoelectric conversion unit. In a storage medium readable by
The control method includes a step of measuring a speed of a moving object that moves a medium, and a step of generating a speed synchronization signal synchronized with a speed signal based on the speed measurement and using the speed synchronization signal as a reference signal of the photoelectric conversion unit. A storage medium that can be applied to image correction performed based on the determination of the gray level of data of each pixel based on reading of the medium. An image reading device for reading an image in a horizontal scanning direction of a medium by a photoelectric conversion unit and reading an image by moving the medium relative to the photoelectric conversion unit in a vertical scanning direction, and forming an image on the medium by a recording head. And a computer-readable storage medium that stores a program that executes a method of controlling an image forming apparatus that forms an image by relatively moving a medium,
The control method includes the steps of: measuring a speed of a moving object that moves a medium; generating a speed synchronization signal synchronized with a speed signal based on the speed measurement and using the speed synchronization signal as a reference signal of the photoelectric conversion unit; Determining the magnitude of the gray level of the data of each pixel based on the reading of the medium by the reading device, and performing image correction at the time of creating image data based on the result of the determination.

Images