JP2004349995A - Color image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image reading apparatus capable of rapidly reading an original in an ADF while suppressing cost. <P>SOLUTION: The image reading apparatus is provided with a document detecting sensor 16 for detecting that a document is in the ADF or in an FBS; line correction memories 7R, 7G, 7B for delaying sensor signals by a required line in order to correct displacement of reading lines of each of line image sensors 2R, 2G, 2B; and a changeover switch 15 for changing the delay amounts of line correction memories 7R, 7B for a delay memory writing control signal S1 and a delay memory writing control signal S3 on the basis of a signal from the sensor 16. The control signal S2 is fixedly connected to the correction memory 7G. The changeover switch 15 changes over a switch as shown in the figure when reading the document by the FBS, and changes over the switch to the opposite side when reading the document by the ADF. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a color image reading device such as a digital color copier.
[0002]
[Prior art]
As a color image reading device, an automatic document feeder (ADF) for automatically feeding a document to a reading position, a flatbed scanner (FBS) for reading a document, and a sub-scanning direction for reading a document (in a longitudinal direction of a line sensor). There are a plurality of (for example, three of RGB) line sensors arranged at intervals in a direction perpendicular to each other, and a line sensor is commonly used for reading an original by the ADF and reading an original by the FBS.
[0003]
For example, an ADF, an FBS, a four-line color CCD sensor having four line sensors (RGB color sensors, a monochrome Y sensor), a selector, an AD converter, a line delay rearranging unit, and a mode setting (color There is an apparatus that performs processing by appropriately switching the order of the output signals of the respective color sensors depending on the (/ monochrome or forward or backward scanning of the document) (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-2002-111968
[Problems to be solved by the invention]
In the apparatus described in Patent Document 1, at the time of reading with the ADF, the document taken out by the ADF is temporarily stopped on the platen glass of the FBS, and in this state, similarly to the time of reading the FBS, the document is positioned below the platen glass. This type scans while moving a carriage on which a 4-line sensor is mounted, that is, the type in which the document reading position in the ADF and the document reading position in the FBS are the same.
[0006]
However, according to this type of apparatus, the original taken out by the ADF is conveyed to the platen glass, stopped on the platen glass, and then moved by the carriage for scanning. When the number is large, the problem becomes remarkable. Even if a complicated circuit is mounted to solve such a problem, it is not preferable to increase the cost.
[0007]
SUMMARY OF THE INVENTION The present invention has been made in view of such current problems, and has as its object to provide a color image reading apparatus capable of quickly reading an original with an ADF while suppressing costs.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a color image reading apparatus according to a first aspect of the present invention includes an automatic document feeder (ADF) for automatically feeding a document to a reading position, and a reading start position different from the reading position. The scanner includes a flatbed scanner (FBS) that starts reading a document and a plurality of line sensors arranged in parallel, and reads a document at a reading position related to the ADF and reads a document from a reading start position related to the FBS. The line sensor is shared, and a judgment means for judging whether to execute reading by the ADF or reading by the FBS, and a sensor signal for correcting a displacement of a reading line of each line sensor are required. The line correction means that delays by an appropriate number of lines and the delay amount of the line correction means for each line sensor based on the determination result of the determination means are cut off. Characterized in that a changing switch means.
[0009]
This device differs from the device described in Patent Document 1 in that the reading position of the document on the ADF and the reading position of the document on the FBS are different. Since the document using the ADF is read at a reading position set for the ADF, that is, a type in which the document is read while being transported while the carriage on which the light source or the like is mounted is stationary (sheet-through type), a patent document is disclosed. Reading in the ADF does not take much time as compared with the apparatus described in (1). In particular, when the number of documents in the ADF is large, the reading time can be considerably reduced.
[0010]
In addition, since the connection mode between each line sensor and the line correction unit is switched based on the result of determining whether to execute reading by the ADF or reading by the FBS, the cost is suppressed by a simple circuit configuration. it can.
[0011]
In the above basic configuration, each line correction unit has the same number of delay cells, and switches the amount of delay by switching a write control signal to each line correction unit.
[0012]
Alternatively, the basic configuration may further include a pixel order changing unit that changes the order of pixels in the main scanning direction (longitudinal direction of the line sensor) with respect to the sensor signal of each line sensor based on the determination result of the determining unit. In this case, when the pixel at one end of the line sensor is set as the start point when reading with the ADF, the pixel at the other end is set as the start point when reading with the FBS. That is, the order of the left and right pixels is switched between when reading with the ADF and when reading with the FBS.
[0013]
A document detection sensor for detecting whether a document is set on the ADF is provided. The determination unit determines whether to perform reading by the ADF or FBS based on a detection signal of the document detection sensor. It may be determined. If there is a document in the ADF before or at the time when the reading start instruction is input by the user, it is determined that the reading is performed by the ADF.
[0014]
On the other hand, a document detection sensor for detecting whether a document is set on the FBS is provided, and the determination means determines whether to execute reading by the ADF or reading by the FBS based on a detection signal of the document detection sensor. It may be determined. If there is a document in the FBS before or at the time when the reading start instruction is input by the user, it is determined that the reading is performed by the FBS.
[0015]
As the document detection sensor related to the FBS, for example, a document size detection sensor related to the FBS or an image reading line sensor (CCD) can be used. In the latter case, in the document width detection performed immediately before the platen cover closes, when it is determined that there is a document, it is determined that reading is performed by the FBS.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to embodiments.
[0017]
FIG. 1 shows a schematic diagram of the internal structure of the color image reading apparatus according to the embodiment. An FBS 60 is provided on an upper part of the apparatus main body, and the FBS 60 has a book platen cover 61 that is hingedly connected to a deep position of the apparatus main body and that can be opened and closed on the front side. An ADF 70 is disposed on the left side of the book platen cover 61. A document supply tray 62 on which a document to be read by the ADF 70 is placed is placed above the document supply tray 62, and a document discharge tray 63 for discharging a document after reading is supplied to the document supply tray 63. Each is provided below the tray 62. The ADF 70, which is an automatic document feeder, automatically feeds documents one by one from a document feed tray 62 to a reading position.
[0018]
In the ADF 70, a separation roller 71 for separating documents one by one is provided at a position close to the document exit of the document supply tray 62, a transfer roller 72 is provided in the document conveyance path, and a document discharge tray 63 is provided. A discharge roller 73 is provided at a position close to the document entrance.
[0019]
At the reading position where the image of the document conveyed by the ADF 70 is read, two mirrors 75 and a three-line color CCD 76 are arranged. The image of the document is reflected by the mirror 75 and imaged by the three-line color CCD 76. Although not shown in the drawings, a light source for irradiating the document is also provided. The three-line color CCD 76 includes RGB pixel sensors, and each pixel sensor has a predetermined scanning position at the same timing in the sub-scanning direction (a direction orthogonal to the longitudinal direction of the CCD 76) for reading a document. It is placed open.
[0020]
As will be described later, here, the three-line color CCD 76 is integrally mounted on a carriage together with a mirror 75 and a light source, and when reading by the ADF 70, the carriage stops the original image at the position shown in FIG. In the case of reading and reading by the FBS 60, the document image is read while moving rightward from the reading start position (document set reference position) on the right side of the position in FIG. That is, in reading by the ADF 70, the original moves to the stationary 3-line color CCD 76, and in reading by the FBS 60, the 3-line color CCD 76 moves to the stationary original.
[0021]
In addition, a light source, a mirror, a lens, and a line sensor are all mounted on the moving carriage, and when reading by FBS, reading is performed while moving each element integrally with the moving carriage (this embodiment). Equipped with a light source and mirror, lens and line sensor are not mounted on the moving carriage. When reading by FBS, reading is performed while the lens and line sensor are stationary and the light source and mirror are moved integrally with the moving carriage. And any type is applicable.
[0022]
FIG. 2 is a block diagram showing a configuration example of the color image reading apparatus. 2, an MPU 21 (central processing unit) has a function of controlling the entire device. Further, the MPU 21 has a function of determining whether to execute reading by the FBS 60 or to execute reading by the ADF 70, as described later.
[0023]
An image reading unit 22, an operation unit 23, a display unit 24, a ROM 25, a RAM 26, a printer 27, an ADF original set sensor 28, and an FBS original set sensor 29 are connected to the MPU 21 via a system bus 20.
[0024]
The image reading unit 22 processes a signal of a document image from the three-line color CCD 76. Specifically, the output of the three-line color CCD 76 is amplified in an analog manner, and the digital data is output in multi-valued form. The operation unit 23 has a start key for instructing start of copying and the like, a numeric keypad for inputting the number of copies, the number of copies, and the like. The display unit 24 displays various information such as the number of copies and the number of copies input by the operation of the operation unit 23 and the remaining amount of toner in the printer 27. As the display unit 24, for example, an LCD (Liquid Crystal Display) is used.
[0025]
The ROM 25 stores in advance programs and the like for controlling the operation of the entire apparatus. The RAM 26 stores data necessary for control by the MPU 21, data that needs to be temporarily stored during control operation, and the like. The printer 27 prints the image data read by the three-line color CCD 76 on paper in color or monochrome.
[0026]
The ADF document set sensor 28 is for detecting whether or not a document is set on the document supply tray 62 related to the ADF 70. The MPU 21 detects whether or not a reading start instruction is input by the user or at the time when the reading start instruction is input. When it is determined that the document is present in the ADF 70, the reading by the ADF 70 is determined. The FBS document set sensor 29 is for detecting whether or not a document is set on a platen cover (not denoted by a reference numeral) relating to the FBS 60. The MPU 21 determines whether a reading start instruction is input by the user or If it is determined that the document is present in the FBS 60 at the time of input, it is determined that reading is performed by the FBS 60.
[0027]
As shown in FIG. 3, the image reading unit 22 includes an R signal processing unit 1R, a G signal processing unit 1G, a B signal processing unit 1B, a color conversion unit 8, an image processing unit 9, an image memory 10, And the output device 11 (the printer 27).
[0028]
The R signal processing unit 1R includes a line image sensor 2R, an analog front end (AFE) circuit 3R, an A / D conversion unit 4R, a shading correction circuit 5R, and a line correction memory (line correction unit) 7R. I have. The G signal processing unit 1G includes a line image sensor 2G, an analog front end circuit 3G, an A / D conversion unit 4G, a shading correction circuit 5G, and a line correction memory 7G. Further, the B signal processing section 1B includes a line image sensor 2B, an analog front end circuit 3B, an A / D conversion section 4B, and a shading correction circuit 5B. Here, the reason that the B signal processing section 1B is not provided with the line correction memory is to delay other R signals and G signals with reference to the B signal.
[0029]
The line image sensor 2R is composed of a CCD, and separates and reads the R signal of the image of one scan line of the document each time a timing signal is applied, and after a predetermined interval, scans the R signal of the image of the next one scan line. The signals are sequentially read, and the read image data of one scan line is output. The analog front end circuit 3R receives the output of the line image sensor 2R and performs analog amplification. The A / D converter 4R receives the analog output of the analog front-end circuit 3R and converts it into a digital signal.
[0030]
Here, the shading correction circuit 5R includes a shading RAM, and the output of the A / D converter 4R at the time of reading a reference plate (white reference plate) is stored in the shading RAM as shading correction data. The shading correction circuit 5R corrects the output of the A / D converter 4R at the time of reading a document by using shading correction data and outputs the result. The line correction memory 7R can store sensor signals for the lines (for example, eight lines) required to correct the displacement of the read line of the line image sensor 2R, and receive the output of the shading correction circuit 5R. The output is delayed by a predetermined line. The same applies to each circuit constituting the other G signal processing section 1G and B signal processing section 1B.
[0031]
Assuming that each interval between the line image sensors 2R, 2G, and 2B corresponds to four scanning lines, the shading correction circuit is delayed by four lines after the R signal of one scanning line is output from the shading correction circuit 5R. The G signal of one scanning line is output from 5G, and the B signal of one scanning line is output from the shading correction circuit 5B with a delay of four lines. Therefore, the R signal is delayed by eight lines in the line correction memory 7R, and the G signal is delayed by four lines in the line correction memory 7G, and is input to the color conversion unit 8, respectively. Therefore, the R, G, and B signals input to the color conversion unit 8 are on the same scanning line.
[0032]
The color converter 8 converts the R, G, B color signals into L ^* , a ^* , b ^* . The data converted into L ^* , a ^* , b ^* by the color conversion unit 8 is temporarily stored in the image memory 10 via the image processing unit 9 and then supplied to the output device 11.
[0033]
This color image reading device determines whether the MPU 21 performs reading by the FBS 60 or reading by the ADF 70, and based on the determination result, the respective line image sensors 2R, 2G, 2B and the line correction memories 7R, 7G, It is characterized by having a changeover switch (switching means) 15 for switching the connection mode with 7B (see FIG. 4).
[0034]
Here, the line correction memories 7R, 7G, and 7B have the same number of storage cells, control the write permission time for each line, and control the R, G, and B signals to be read simultaneously at the time of reading, thereby controlling the same line. The above data is output.
[0035]
On the other hand, the write control signal S1 is a control signal for writing a signal for one line, which is input first, of the read signals of R, G, and B into the line correction memory. The write control signal S2 is a control signal for writing the next signal into the line correction memory with a delay corresponding to the line between the line image sensors compared to the write control signal S1. Further, the write control signal S3 is a control signal for writing a signal of one line of the read signal input with the first delay into the line correction memory.
[0036]
Now, the R, G, and B images at the same line position of the document are sequentially input to the shading correction circuits 5R, 5G, and 5B, and the R signal, that is, the signal from the shading correction circuit 5R, is output first. , The signal from the shading correction circuit 5G is output with a delay of four lines. It is also assumed that the B signal, that is, the signal from the shading correction circuit 5B is output with a delay of eight lines.
[0037]
In this case, a delay memory write control signal S1 is applied to the line correction memory 7R, a delay memory write control signal S2 is applied to the line correction memory 7G, and a delay memory write control signal is applied to the line correction memory 7B. S3 is added. Therefore, one line of the R signal output from the shading correction circuit 5R first is written and stored in the line correction memory 7R by the delay memory write control signal S1. Next, when the G signal is output from the shading correction circuit 5G with a delay of four lines, the G signal for one line is written and stored in the line correction memory 7G by the delay memory write control signal S2. Further, when the B signal is output from the shading correction circuit 5B with a delay of four lines (eight lines from the R signal), the B signal for one line is output by the delay memory write control signal S3 to the line correction memory 7B. Is written and stored. At this time, if the contents stored in the line correction memories 7R, 7G, and 7B are simultaneously read, the R, G, and B signals at the same line position of the document are output simultaneously.
[0038]
When the B signal, that is, the data of the shading correction circuit 5B is output earlier with respect to the R, G, and B data at the same line position of the original, the changeover switch 15 is turned on in the reverse direction. When the changeover switch 15 is switched, the delay memory write control signal S1 is input to the line correction memory 7B and the delay memory write control signal S3 is input to the line correction memory 7R. Conversely, writing to the line correction memory 7B is performed. This is the earliest, and the writing to the line correction memory 7R is the latest. Then, the R, G, and B signals at the same line position of the original are output simultaneously from the line correction memories 7R, 7G, and 7B.
[0039]
Here, the scanning order of each line image sensor when reading each image of the FBS 60 and the ADF 70 will be described. In FIG. 5, in the case of reading by the ADF 70, the carriage 30 having three line image sensors stops at the illustrated position, and reads the original 41 conveyed by the ADF 70 at the reading position A. On the other hand, in the case of reading by the FBS 60, the carriage 30 reads the document 42 on the FBS 60 (platen glass) while moving rightward from the reading start position (document set reference position) B.
[0040]
That is, at the time of reading by the ADF 70, as shown in FIG. 6, since the original 41 moves in the direction of the arrow with respect to the three line image sensors RGB in the stationary state, the scanning order of one line of the original 41 is determined by the B line image sensor. First, the G line image sensor is the second, and the R line image sensor is the third. On the other hand, at the time of reading by the FBS 60, as shown in FIG. 7, since the three line image sensors RGB move in the direction of the arrow with respect to the stationary document 42, the scanning order of one line of the document 42 is R line. The image sensor is the first, the G line image sensor is the second, and the B line image sensor is the third. Therefore, the connection mode is switched between when reading with the FBS 60 and when reading with the ADF 70.
[0041]
FIG. 4 shows a circuit of the image reading unit 22 in this case. However, the same elements as those in FIG. 3 are denoted by the same reference numerals, and a part of the configuration is omitted. As is apparent from a comparison between FIG. 4 and FIG. 3, in the circuit of FIG. 4, a line correction memory 7B is provided at a stage subsequent to the shading correction circuit 5B of the B signal processing unit 1B, and each of the line correction memories 7R, 7G, A changeover switch (switching means) 15 for switching a connection mode between the delay memory write control signal S1 (12) and the delay memory write control signal S3 (14) and the line correction memories 7R and 7B is provided in a stage preceding the 7B. ing. However, the scanning order of the G line image sensor is the second between the reading by the FBS 60 and the reading by the ADF 70, so that the delay memory write control signal S2 (13) and the line correction memory 7G are fixedly connected.
[0042]
Here, the delay memory write control signal S1 is a signal delayed by eight scan lines, the delay memory write control signal S2 is a signal delayed by four scan lines, and the delay memory write control signal S3 is a signal not delayed. A document presence / absence signal from the document detection sensor 16 (ADF document set sensor 28 or FBS document set sensor 29) is input to the changeover switch 15, and the changeover switch 15 switches the switch based on the signal.
[0043]
When reading by the FBS 60 is performed, when a signal indicating that a document is present in the FBS 60 is input to the changeover switch 15 by the document detection sensor 16, the changeover switch 15 switches the switch according to the reading by the FBS 60 as illustrated. Thereby, the delay memory write control signal S1 is connected to the line correction memory 7R, and the delay memory write control signal S3 is connected to the line correction memory 7B. As a result, the R signal is relatively delayed by eight lines with respect to the B signal, and the G signal is relatively delayed by four lines, so that each of the R, G, and B signals input to the color conversion unit 8 is output. Are on the same scan line.
[0044]
On the other hand, when reading is performed by the ADF 70, when a signal indicating that a document is present in the ADF 70 is input to the changeover switch 15 by the document detection sensor 16, the changeover switch 15 switches the switch to the side opposite to the illustration according to the reading by the ADF 70. As a result, the delay memory write control signal S1 is connected to the line correction memory 7B, and the delay memory write control signal S3 is connected to the line correction memory 7R. As a result, since the B signal is relatively delayed by 8 lines and the G signal is relatively delayed by 4 lines with respect to the R signal, each of the R, G, and B signals input to the color conversion unit 8 is output. Are on the same scan line.
[0045]
【The invention's effect】
According to the present invention, the following effects can be obtained.
(1) No time is required for reading by the ADF. In particular, when the number of documents in the ADF is large, the reading time can be considerably reduced.
(2) The circuit configuration is simple, and the cost can be reduced.
(3) The order of signals can be changed without key input by the user.
(4) Since the switching is performed before the line correction unit, the processing circuit at the subsequent stage (circuits after the line correction unit) can be used without any setting change between reading by the ADF and reading by the FBS. That is, both reading by the ADF and the FBS can be realized without affecting the configuration and control of the line correction circuit and the shift correction circuit.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an internal structure of a color image reading device according to an embodiment.
FIG. 2 is a block diagram illustrating a configuration example of the color image reading apparatus.
FIG. 3 is a block diagram illustrating a configuration example of an image reading unit in the block diagram of FIG. 2;
FIG. 4 is a block diagram showing another configuration example of the image reading unit in the block diagram of FIG. 2;
FIG. 5 is a diagram for explaining a scanning order of each line image sensor when reading each image of the FBS and the ADF.
FIG. 6 is a diagram illustrating a scanning order of three line image sensors RGB for a document when reading by the ADF.
FIG. 7 is a diagram illustrating a scanning order of three line image sensors RGB for a document at the time of reading by FBS.
[Explanation of symbols]
1R R signal processing unit 1G G signal processing unit 1B B signal processing unit 2R, 2G, 2B Line image sensor 3R, 3G, 3B Analog front end (AFE) circuit 4R, 4G, 4B A / D conversion unit 5R, 5G, 5B Shading correction circuits 7R, 7G, 7B Line correction memory (line correction means)
8 color conversion unit 9 image processing unit 15 changeover switch (switching means)
16 Document detection sensor 21 MPU (judgment means)
22 Image reading unit 28 ADF original set sensor 29 FBS original set sensor 60 Flatbed scanner (FBS)
70 Automatic Document Feeder (ADF)
76 3-line color CCD

Claims (5)

An automatic document feeder that automatically supplies a document to a reading position, a flatbed scanner that starts reading a document from a reading start position different from the reading position, and a plurality of line sensors arranged in parallel, A color image reading device that shares the line sensor for reading a document at a reading position according to a supply device and reading a document from a reading start position according to a flatbed scanner,
Judgment means for judging whether to execute reading by the automatic document feeder or reading by the flatbed scanner, and a line for delaying a sensor signal by a necessary line in order to correct a displacement of a reading line of each line sensor. A color image reading apparatus comprising: a correction unit; and a switching unit that switches a delay amount of the line correction unit for each line sensor based on a determination result of the determination unit. 2. The color image reading apparatus according to claim 1, wherein each of the line correction units has the same number of delay cells, and switches the amount of delay by switching a write control signal to each line correction unit. 3. The color image reading device according to claim 1, further comprising a pixel order changing unit that changes the order of pixels in the main scanning direction with respect to a sensor signal of each line sensor based on a determination result of the determining unit. . A document detection sensor for detecting whether a document is set in the automatic document feeder is provided, and the determination unit performs reading by the automatic document feeder or a flatbed scanner based on a detection signal of the document detection sensor. 4. The color image reading device according to claim 1, wherein it is determined whether to execute reading. A document detection sensor for detecting whether a document is set on the flatbed scanner is provided, and the determination unit performs reading by the automatic document feeder or reading by the flatbed scanner based on a detection signal of the document detection sensor. 4. The color image reading apparatus according to claim 1, wherein it is determined whether or not to execute.

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