JP2000216956A - Image reading device and its method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine whether or not the original is a black and white original or a color original, and to sharply shorten a copying time. SOLUTION: A deciding operation for deciding whether or not an original is monochromatic or color is started (S3), before the scanning of the whole face of the original by prescan is ended, and when decision is made before the scanning of the whole face of the original is ended, a first mirror unit is returned to a scanning start position for preparing for the reading of the original (S4), and the monochromatic reading and color reading is selectively executed, based on the decided result (S5 and S6).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, an image reading method, and a storage medium, and more particularly, to an image reading apparatus that selectively executes monochrome reading and color reading.

[0002]

2. Description of the Related Art Conventionally, in a color copying machine, when a document image is a black and white document, a copy image is formed only with black (Bk) toner, and when the document image is a color document, magenta (M) and cyan ( C), yellow (Y) and black (Bk) are used to form a copied image using four color toners. Therefore, a prescan operation is performed before the start of the copying operation to determine whether the original is a monochrome original or a color original (ACS operation).

FIG. 12 shows a scanning time and a home position of the scanning system (hereinafter referred to as H) in the scanning system used for image reading.
Described as P. )) And its displacement. In FIG. 12, the horizontal axis represents time, and the vertical axis represents displacement of the scanning system from the HP. The period from t20 to t21 is a period for accelerating the scanning system to a predetermined speed for performing the prescan operation. The period from t21 to t22 is a reading period for capturing image data of the document as a digital signal. Here, data of the maximum document width A3 size that can be read by the apparatus is captured. The period from t22 to t23 is a period for returning the scanning system to the HP. t23 to t2
In the four periods, it is determined whether the original is a black-and-white image or a color image based on the acquired original image data, and predetermined settings are made to the signal processing unit and the printer unit based on the determination result. The period from t24 to t25 is a period for accelerating the scanning system to a predetermined speed in order to actually perform the reading operation of the original image. A period from t25 to t26 is a reading operation period of the original image, and a period from t26 to t27 is a period for returning the scanning system to the HP.

[0004]

Normally, the shorter the time required for the prescan operation, the shorter the time required for copying the original document. Therefore, it is desirable that the time period from t20 to t24 shown in FIG. 12 be short. However, in the past, since the entire document was fetched at the time of pre-scanning, it was determined whether the document was a black and white image or a color image. Since the entire surface is pre-scanned, the time required for the pre-scan increases. As a result, there is a disadvantage that the copying time cannot be reduced.

In order to solve the above-mentioned problems, the present invention provides an image reading apparatus, an image reading method, and an image reading method which not only determine whether a document is a black-and-white document or a color document, but also greatly reduce a copying time. It is intended to provide a storage medium.

[0006]

An image reading apparatus according to the present invention reads an image as an electric signal line by line by moving a scanning system relative to an image of a document. The system has a determination unit for determining whether a document image is a monochrome document or a color document by preliminary scanning of the system, and starts the determination operation before the scanning of the entire document by the preliminary scanning is completed. If the determination is made before the end of the process, the scanning system is returned to the scanning start position to prepare for reading of the document, and the monochrome reading and the color reading are selectively executed based on the determination result.

One embodiment of the image reading apparatus of the present invention has a counting means for counting the number of color pixels of the original image, and the determination by the determining means is based on the number of color pixels counted by the counting means. It is done.

An image reading method according to the present invention is a method in which a scanning system is moved relative to an image of a document and the image is read line by line.
First to determine whether a document is monochrome or color
And a second step of selectively executing monochrome reading and color reading based on the determination result, wherein the first step is performed before scanning of the entire original by the preliminary scanning is completed. And if the determination is made before the scanning of the entire surface of the document is completed, the scanning system is returned to the scanning start position to prepare for the second step.

One aspect of the image reading method of the present invention includes a third step of counting the number of color pixels of the original image by the preliminary scanning, prior to the first step, The determination operation is performed based on the number of color pixels counted by the counting unit.

[0010] The storage medium of the present invention stores a program for causing a computer to function as each unit of the image reading device in a computer-readable manner.

The storage medium of the present invention stores a program for causing a computer to execute each step of the image reading method in a computer-readable manner.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on preferred embodiments. In the following embodiments, a copying apparatus is shown as an example of application of the present invention, but it is needless to say that the present invention is not limited to this and can be applied to various other apparatuses.

FIG. 1 shows the appearance of the image reading apparatus of the present embodiment. In FIG. 1, reference numeral 201 denotes an image scanner, which reads a document and performs digital signal processing. Reference numeral 202 denotes a printer unit which prints out an image corresponding to the document image read by the image scanner 201 on a recording sheet in full color.

In the image scanner unit 201, 20
Numeral 0 is a mirror surface thick plate, and a platen glass (hereinafter, platen) 2
The original 204 on the original 03 is irradiated with the light of the halogen lamp 205, and the reflected light from the original
The image is formed on a three-line sensor (hereinafter, sensor) 210 by a lens 209 and sent to the signal processing unit 211 as full-color information (red (R), green (G), and blue (B) components).

Note that the first mirror unit 2061 having the halogen lamp 205 and the reflection mirror 206 has a speed v
The second mirror unit 20 having the reflection mirror 207
Reference numeral 71 denotes 1/2 V, which is driven by a motor (not shown) in a direction (hereinafter, a sub-scanning direction) perpendicular to an electrical scanning direction (hereinafter, a main scanning direction) of the line sensor.
Scans the entire original. Reference numeral 5102 denotes a standard white plate, which is used for correction data of data read by the sensor 210 when the halogen lamp 205 is used.

When the original is a color image, the signal processing unit 211 electrically processes the read signal and outputs each component of magenta (M), cyan (C), yellow (Y), and black (Bk). And sends it to the printer unit 202.
In addition, for one document scan (scan) in the image scanner unit 201, one component among M, C, Y, and Bk is sent to the printer 202, and one printout is performed by a total of four document scans. Complete. If the original is a black and white image, the signal processing unit 211 electrically processes the read signal and sends a black (Bk) component signal to the printer unit 202.

The M, C, Y, and Bk image signals sent from the image scanner unit 201 are transmitted to the laser driver 21.
Sent to 2. The laser driver 212 modulates and drives the semiconductor laser 213 according to the image signal. The laser light is reflected by a polygon mirror 214, an fθ lens 215, and a mirror 216.
Scans over the photosensitive drum 217 via the.

Reference numeral 218 denotes a rotary developing device, which includes a magenta developing device 219, a cyan developing device 220, and a yellow developing device 22.
1. A black developing unit 222 is provided. The four developing units alternately contact the photosensitive drum, and develop the M, C, Y, and Bk electrostatic latent images formed on the photosensitive drum 217 with the corresponding toner.

Reference numeral 223 denotes a transfer drum, which winds the paper fed from the paper cassette 224 or 225 around the transfer drum 223, and transfers the toner image developed on the photosensitive drum 217 to the paper.

After the four colors of M, C, Y, and Bk are sequentially transferred in this manner, the sheet passes through the fixing unit 226 and is discharged.

FIG. 2 shows the configuration of the sensor 210 used in this embodiment. Here, 210-1, 210-2, 210
Reference numeral -3 denotes a light receiving element array for sequentially reading R, G, and B wavelength components.

The three light receiving element rows having different optical characteristics are monolithically mounted on the same silicon chip so that the R, G, and B sensors are arranged in parallel with each other to read the same line of the document. It is configured.

FIG. 3 is an enlarged view of the light receiving element. Each sensor has a length of 10 μm per pixel in the main scanning direction. Each sensor is 400d in the short direction (297mm) of A3 document
In order to enable reading at a resolution of pi, 5000 pixels are provided in the main scanning direction. Also, R, G, B
Of each sensor is 80 μm, and 4001
8 lines away from the pi sub-scanning resolution. Further, in each line sensor, an optical filter is formed on the sensor surface in order to obtain predetermined R, G, B spectral characteristics.

Referring to FIG. 4, R, G, B of sensor 210
The spectral characteristics of the line sensor will be described. Each line sensor R, G, B has an optical filter formed on the sensor surface in order to obtain a predetermined spectral characteristic.

FIG. 4A shows R,
These are the characteristics of the G and B filters. As can be seen from this figure, since the conventional R, G, B filters have sensitivity to infrared light of 700 nm or more, the lens 209 is provided with the infrared cut filter shown in FIG. ing.

FIG. 5 is a block diagram showing the flow of an image signal in the image scanner unit 201. An image signal output from the CCD 210 is output to an analog signal processing unit 4001.
After being converted into an 8-bit digital image signal in the analog signal processing unit 4001, the digital image signal is input to the shading correction unit 4002.

Reference numeral 419 denotes a main scanning address counter.
Reset at the rising edge of HSYNC, CLK
It is counted up at the timing of the signal, and generates a 13-bit main scanning address (X address) AX12 to AX0. Reference numeral 420 denotes a sub-scanning address counter,
It is reset in the section of "0" of the NC signal and counted up at the timing of the HSNCY signal to generate 13-bit sub-scanning addresses (Y addresses) AY12 to AY0. A decoder 4008 decodes the main scanning address from the main scanning address counter 419 and generates a line-by-line CCD drive signal such as a shift pulse or a reset pulse. A decoder 4201 decodes a sub-scanning address from the sub-scanning address counter 420 and outputs an ACS signal at a predetermined timing.

FIG. 6 is a block diagram of the analog signal processing section 4001. Here, since the processing circuits for R, G, and B are all the same, a circuit for one color is shown. CCD210
Is output from the sample-and-hold unit (S
(/ H unit) 4101 is sampled and held to stabilize the waveform of the analog signal. The CPU 417 controls the variable amplifier 4103 and the clamp circuit 4102 via the voltage control circuit 4103 so that the image signal can fully utilize the dynamic range of the A / D converter 4105.
Control. The A / D converter 4105 converts the analog image signal into an 8-bit digital image signal.

The 8-bit digital image signal is subjected to shading correction by known shading correction means in a shading correction unit 4002. At the time of reading shading data, the CPU sends a read signal for one line from the standard white plate 5102 to the read signal from the sensor 210 in the line memory 4003.
The multiplication coefficient for obtaining the read data of each pixel recorded in the line memory at the 255 level is obtained for each pixel, and the multiplication coefficient is stored in the coefficient memory 4006 for one line. Then, at the time of actual document reading, a multiplication coefficient corresponding to the pixel is read out from the coefficient memory in synchronization with the output of each pixel by the line reading of the sensor 210, and is applied to each pixel signal from the sensor 210 by the multiplier 4007. Perform shading correction.

As shown in FIG. 2, since the light receiving sections 210-1, 210-2, 210-3 of the sensor 210 are arranged at a fixed distance, the delay elements 401, 402
In, the spatial shift in the sub-scanning direction is corrected. Specifically, R, which reads the original in the sub-scanning direction in response to the B signal,
Each G signal is delayed in the sub-scanning direction to match the B signal.
Reference numerals 403, 404, and 405 denote log converters, each formed by a look-up table ROM, and convert a luminance signal into a density signal. Reference numeral 406 denotes a well-known masking and UCR circuit, which will not be described in detail. According to the input three primary color signals, Y, M, C, and Bk signals for output are sequentially converted into predetermined bits every time a multi-read operation is performed. It is output with a length of, for example, 8 bits.

FIG. 7 is an operation timing chart of each section during a copying operation in the image scanner section of the present embodiment.
The VSYNC signal is an image effective section signal in the sub-scanning direction, and in the section “1”, image reading (scanning) is performed.
(C), (M), (Y), and (Bk) are sequentially formed. VE is an image valid section signal in the main scanning direction, and takes a timing of a main scanning start position in a section of “1”. The CLK signal is a pixel synchronization signal, and transfers image data at the rising timing of 0 → 1.

A CPU 417 controls the apparatus in each mode. A window converter 4009 determines whether or not a specific level signal specified by the CPU 417 has been input. In the block processing circuit 409,
A 16 × 16 block process is performed, and the output of the window comparator 4009 is processed for each 16 × 16 block. 418 is a RAM / ROM added to the CPU 417
It is.

FIG. 8 shows the window comparator 40 shown in FIG.
FIG. 9 is a block diagram of the pixel 09, in which it is determined whether each pixel is a monochrome pixel or a color pixel based on an 8-bit R, G, B image signal. In 621, 622, and 623, the input R, G,
G × 128 / R, B × 128 /
G, R × 128 / B is calculated, and the calculation result is compared with comparators 607, 608, 609, 610, 611,
612. 607, 608, 609, 610,
Reference numerals 611 and 612 denote comparators, whose outputs become 1 only when A> B holds for the inputs A and B.

Reference numeral 613 denotes a 6-input OR gate. Now, the registers 601, 602, 603, 604, 60
RGL and R are respectively assigned to the CPUs 417 and 5,606.
When values GH, GBL, GBH, BRL, and BRH are written, for input signals R, G, B, RGL> G × 128 / R or G × 128 / R> RGH or GBL> B × 128 Window comparator 4009 only when / G or B × 128 / G> GBH or BRL> R × 128 / B or R × 128 / B> BRH holds.
Is "1", otherwise it is "0".

In this embodiment, the window comparator 4
By adjusting the threshold of 009, the R, G, and B signals are set to 70H> G × 128 / R or G × 128 / R> 90H or 70H> B × 128 / G or B × 128 / G> 90H or 70L > R × 128 / B or R × 128 / B> 90H, each pixel is determined to be a color image.

FIG. 9 is a diagram showing the internal details of the 16 × 16 block processing circuit 409 shown in FIG. 701, 7
, 714, 715 are 15 D flip-flops (hereinafter referred to as DFFs) arranged in series, which sequentially delay the input signal with the pixel clock CLK signal. VE = "0" Cleared to "0" in the non-image section. 738 is a 5-bit up / down counter, 737 is an EX-OR gate, 740 is an AND gate, and the operation is based on Table 1 below.

[0037]

[Table 1]

That is, the output of the counter 738 is VSYN
When C or VE is “0”, it is cleared to 0, and Xt =
It is held at the time of Xt-15, Xt = 1 and Xt-15
= 0, the count is incremented, and Xt = 0 and Xt−
When 15 = 1, the countdown is performed. That is, as a result, the sum total (= 1 number) of 16 data Xt to Xt-15 is output.

Further, the output is passed through DFF739 to 1
FIFO memories 721, 722, 723 in line units,
, 732, 735, the data for 16 lines are simultaneously input to the adder 741, and the sum thereof is output. As a result, the sum S of the numbers of 1 in the 16 × 16 window
UM is output from 0 to 256.

Reference numeral 742 denotes a digital comparator which compares the output SUM of the adder 741 with a comparison value TW predetermined by the CPU 417, and outputs the result as "0" or "1".

Therefore, by setting an appropriate number in TW in advance, it is possible to remove noise in units of 16 × 16 blocks (here, TW = 128).

20101 is a counter, 16 × 16
The number of color pixel blocks of the document from which noise has been removed by the block processing circuit 409 is counted by CLK. In this embodiment, an 8-bit down counter is used.
The counting of 55 color pixels is performed.

Reference numeral 20202 denotes an 8-bit register.
A value between 0 and 255 can be set by the CPU.
At 101, the counter value is decreased by one for each color pixel block from the value set in the register 20202, and when the count value becomes 0, the color signal (COLOR signal) is output to the interrupt terminal of the CPU 417 and the flip-flop (F / F) 20103. When the CPU 417 detects that a color signal has been input to the interrupt terminal, it determines that the document is a color image. That is, the document is pre-scanned, and when the number of color pixel blocks of the document becomes equal to the value set in the register 20202, the document is determined to be a color image.

Reference numeral 20102 denotes a 4-input AND gate, which is a main scanning section signal VE and a sub-scanning section signal VSYNC.
When (“H”) is generated, a binarized color signal output from the window comparator 4009 is given as an enable signal of the counter 20101. The counter 20101 is set in the register 20 by the SET signal from the CPU.
Although the value set in 202 is set, the flip-flop (F / F) 20103 is set by this SET signal, and the output from the gate 20102 is enabled. Also,
The F / F 20103 is reset by the color signal, the enable input of the counter is forcibly set to “0”, and the output of the counter is held at 0.

Hereinafter, the actual operation will be described with reference to the flowchart of FIG. When the operator places a document on the platen 203 and starts a copy operation from an operation unit (not shown), the CPU 417 sets the registers 601 to 606
Is set, and then a motor (not shown) is controlled to move the first mirror unit 2061 to start pre-scan (step S1), and the number of color pixels is counted by the counter 20101 (step S2). . Next, the CPU 417 continues to refer to the color signal output from the counter 20101, and determines whether the original is a monochrome image or a color image (step S3).

When the original is determined to be a color image,
Return the first mirror unit 2061 to HP (step S
4), setting for copying a color image to the signal processing unit 211 and the printer unit 202 is performed (step S5). When the document is determined to be a black and white image (when the number of color pixel blocks does not reach a predetermined value even when the apparatus performs a prescan operation of a maximum document width A3 size),
The settings for copying the black and white image are made in the signal processing unit 211 and the printer unit 202 (step S6), and then the copying operation is performed (step S7), and a series of operations is completed.

FIG. 11 shows the relationship between the scanning time and the displacement from the home position of the scanning system (hereinafter, referred to as HP) by the first mirror unit 2061 as the scanning system. In FIG. 11, the horizontal axis represents time, and the vertical axis represents displacement of the first mirror unit 2061 from the HP. Here, the period from t10 to t11 is a period for accelerating the first mirror unit 2061 to a predetermined speed in order to perform the prescan operation.

The period from t11 to t12 is a reading period for taking in the image data of the original as a digital signal. At the timing of t12 (before the completion of the data taking in of the whole original), the color signal is outputted from the counter 20101, and One mirror unit 2061 is returned to HP. During the period from t12 to t13, the first mirror unit 2061
Is returned to the HP. In the period from t13 to t14, it is determined whether the original is a black-and-white image or a color image, and predetermined settings are made to the signal processing unit 211 and the printer unit 202 based on the determination result. The period from t14 to t15 is a period for accelerating the first mirror unit 2061 to a predetermined speed in order to actually perform the reading operation of the original image. A period from t15 to t16 is a reading operation period of the original image, and a period from t16 to t17 is the first mirror unit 20.
This is a period for returning 61 to HP.

As described above, according to the image reading apparatus of the present embodiment, if the original is determined to be a color image during the prescan operation, the prescan operation is immediately stopped and the copy operation is started. By doing so, it is possible not only to determine whether the document is a black-and-white document or a color document, but also to greatly reduce the copying time.

In order to realize the functions of the image reading apparatus described in the present embodiment, the program code itself for operating various devices, means for supplying the program code to a computer, and an image reading method The program code itself for realizing the respective steps (steps S1 to S7 in FIG. 10 and the like) and means for supplying the program code to a computer, for example, a storage medium storing the program code are within the scope of the present invention. Belongs to.

In this case, the program code stored in the storage medium is read out by a predetermined storage / reproduction device, and the EEPROM operates. As a storage medium for storing such a program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.

When the computer executes the supplied program code, not only the functions of the present embodiment are realized, but also the OS (Operating System) or other application running on the computer in the program code. Such a program code is also included in the present invention when the functions of the present embodiment are realized in cooperation with software or the like.

Further, after the supplied program code is stored in a memory provided in a function expansion board of a computer or a function expansion unit connected to the computer, the function expansion board or the function expansion unit is operated based on the instruction of the program code. The present invention also includes a system in which a CPU or the like included in the system performs part or all of actual processing, and the processing realizes the functions of the present embodiment.

[0054]

According to the present invention, when a document is determined to be a color image during a pre-scan (pre-scan) operation, the pre-scan operation is immediately stopped, and a copy operation is performed. In addition to determining whether a document is a (monochrome) document or a color document, the copying time can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an appearance of an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of a reading sensor used in the embodiment.

FIG. 3 is an enlarged schematic view showing a light receiving element of the line sensor.

FIG. 4 is a characteristic diagram for explaining the spectral characteristics of a line sensor.

FIG. 5 is a block diagram illustrating a flow of an image signal in the image scanner unit.

FIG. 6 is a block diagram illustrating an analog signal processing unit.

FIG. 7 is an operation timing chart of each unit during a copying operation in the image scanner unit.

FIG. 8 is a block diagram of the window comparator shown in FIG.

FIG. 9 is a circuit diagram showing internal details of the 16 × 16 block processing circuit shown in FIG. 5;

FIG. 10 is a flowchart illustrating a copying operation using the image reading apparatus according to the embodiment of the present invention.

FIG. 11 is a characteristic diagram illustrating a relationship between a scanning time by a scanning system and a displacement from a home position of the scanning system in the image reading apparatus according to the embodiment of the present invention.

FIG. 12 is a characteristic diagram illustrating a relationship between a scanning time by a scanning system and a displacement from a home position of the scanning system in a conventional image reading apparatus.

DESCRIPTION OF SYMBOLS 201 Image scanner unit 202 Printer unit 203 Platen 204 Document 210 Line sensor 211 Signal processing unit 419 Main scanning address counter 601 to 606 Register 607 to 612 Comparator 2061 First mirror unit 4001 Analog signal processing unit 4002 Correction unit 4009 Window comparator 20101 counter 20202 register

Claims (6)

[Claims] 1. An image reading apparatus for reading an image as an electric signal line by line by moving a scanning system relative to an image of an original, wherein the preliminary scanning of the scanning system determines whether the original image is a monochrome original. A determination unit for determining whether the original is a color original, wherein the determination operation is started before the scanning of the entire original by the preliminary scanning is completed, and the determination is performed before the scanning of the entire original is completed. An image reading apparatus that returns the scanning system to a scanning start position and prepares for reading a document, and selectively executes monochrome reading and color reading based on the determination result. 2. The image processing apparatus according to claim 1, further comprising a counting unit that counts the number of color pixels of the document image, wherein the determination by the determining unit is performed based on the number of color pixels counted by the counting unit. Item 2. The image reading device according to Item 1. 3. An image reading method in which a scanning system is moved relative to an image of a document to read the image line by line, wherein whether the document is a monochrome document or a color document is determined by preliminary scanning of the scanning system. And a second step of selectively executing monochrome reading and color reading based on the result of the determination. The method further comprises: An image reading method, wherein the first step is started, and if the determination is made before the scanning of the entire surface of the document is completed, the scanning system is returned to a scanning start position, and the method is prepared for the second step. . 4. The method according to claim 1, further comprising: a third step of counting the number of color pixels of the original image by the preliminary scanning, prior to the first step, wherein the determining operation in the first step is performed by the counting unit. 4. The image reading method according to claim 3, wherein the method is performed based on the counted number of color pixels. 5. A storage medium, wherein a program for causing a computer to function as each unit of the image reading apparatus according to claim 1 or 2 is stored in a computer-readable manner. 6. A storage medium wherein a program for causing a computer to execute each step of the image reading method according to claim 3 or 4 is stored in a computer-readable manner.