WO2006011450A1 - 画像読取装置及び画像読取方法 - Google Patents
画像読取装置及び画像読取方法 Download PDFInfo
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- WO2006011450A1 WO2006011450A1 PCT/JP2005/013583 JP2005013583W WO2006011450A1 WO 2006011450 A1 WO2006011450 A1 WO 2006011450A1 JP 2005013583 W JP2005013583 W JP 2005013583W WO 2006011450 A1 WO2006011450 A1 WO 2006011450A1
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- light
- light emitting
- emitting elements
- light emission
- image
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/40—Picture signal circuits
- H04N1/40056—Circuits for driving or energising particular reading heads or original illumination means
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B27/00—Photographic printing apparatus
- G03B27/32—Projection printing apparatus, e.g. enlarger, copying camera
- G03B27/52—Details
- G03B27/54—Lamp housings; Illuminating means
- G03B27/542—Lamp housings; Illuminating means for copying cameras, reflex exposure lighting
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/024—Details of scanning heads ; Means for illuminating the original
- H04N1/028—Details of scanning heads ; Means for illuminating the original for picture information pick-up
- H04N1/02815—Means for illuminating the original, not specific to a particular type of pick-up head
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/024—Details of scanning heads ; Means for illuminating the original
- H04N1/028—Details of scanning heads ; Means for illuminating the original for picture information pick-up
- H04N1/02815—Means for illuminating the original, not specific to a particular type of pick-up head
- H04N1/0282—Using a single or a few point light sources, e.g. a laser diode
- H04N1/02835—Using a single or a few point light sources, e.g. a laser diode in combination with a light guide, e.g. optical fibre, glass plate
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/46—Colour picture communication systems
- H04N1/48—Picture signal generators
- H04N1/482—Picture signal generators using the same detector device sequentially for different colour components
- H04N1/484—Picture signal generators using the same detector device sequentially for different colour components with sequential colour illumination of the original
Definitions
- the present invention relates to an image reading apparatus and an image reading method, and is particularly suitable for use in reading image information.
- An image reading apparatus such as an image scanner generally has a configuration as shown in FIG. In FIG. 19, the image sensor unit 1 converts the optical information from the document sheet 7 placed on the document table glass plate 4 into an electrical signal.
- the displacement unit 2 changes the relative position of the original paper 7 and the image sensor unit 1 and changes the reading position of the original paper 7.
- the control unit 3 drives the image sensor unit 1 and the displacement unit 2 and processes electrical signals from the image sensor unit 1.
- RGB Red, green, and blue
- RGB LED Light Emitting Diode
- FIG. 8 is a cross-sectional view showing a configuration of a conventional image sensor (hereinafter abbreviated as CIS) which is a light source switching type image sensor unit 1 as a conventional technique.
- CIS a conventional image sensor
- the light emitted from the light source 41 disposed on the end face of the light guide 12 enters the light guide 12 and is guided in the longitudinal direction, and is placed on the platen glass 4. Illuminate the reading section of the original paper 7 in a line shape in the main scanning direction. The reflected light from the original paper 7 illuminated in this way is collected by the lens array 14, transmitted to the sensor array 15 disposed on the sensor substrate 16, and converted into an electrical signal. Original image obtained in this way The electrical signal corresponding to is output from the connector 17 to the outside.
- reference numeral 13 denotes a frame for fixing constituent members such as the light guide 12, the lens array 14, and the sensor substrate 16 at predetermined positions.
- the light source 41 is provided with three LEDs 41r, 41g, and 41b having different emission wavelengths. These three LEDs 41r, 41g, and 41b emit red, green, and blue light, respectively. As shown in FIG. 9, these LEDs are wired using one common wiring and each individual wiring, and each LED 41r, 41g, 41b can be individually controlled to be lit.
- the image sensor unit 1 and the displacement unit 2 that changes the relative position between the document sheet 7 and the image sensor unit 1 are driven by the control unit 3 at a predetermined timing.
- the control unit 3 converts optical information from the original paper 7 into an electrical signal. The operation of this control unit 3 will be described below.
- FIG. 10 is a block diagram showing a conventional technique and showing a configuration of an image reading apparatus.
- the control unit 3 uses the light source controller 33 and the sensor controller 34 to drive the image sensor unit 1 according to the timing chart shown in FIG.
- the sensor array 15 (Fig. 8) composing the image sensor unit 1 integrates image information during one operation cycle period, with one period of the synchronization signal SP input from the external force as the image information accumulation period TS. The output image information is output during the next operation cycle.
- a period TC corresponding to three periods of the image information accumulation period TS of the sensor array 15 is defined as one period of the color reading operation, and the light source controller shown in FIG. 12 is provided for each operation cycle period in this period TC.
- the LEDs 41r, 41g, 41b of the light source 41 are individually turned on sequentially by the control signal () Lr, Lg, ⁇ ⁇ ).
- the original paper 7 is color-separated by the light emission spectrum of each LED 41r, 41g, 41b, so-called light source switching type color separation is performed, and image information output (line output) that is color-separated line-sequentially OS (r), OS (g), and OS (b) are obtained.
- the control unit 3 drives the image sensor unit 1 as described above, and drives the displacement unit 2 by the displacement unit controller 32 in synchronization with the image sensor unit 1.
- the two-dimensional image information of the original paper 7 is collected. Gather.
- conventional image signal processing performed by the control unit 3 will be described.
- control unit 3 Prior to the reading operation of the original paper 7, the control unit 3 first performs the following preparatory operation.
- the control unit 3 controls the displacement unit 2 to move the image sensor unit 1 to a predetermined initial position.
- a white reference plate 5 is installed on the platen glass 4 at the initial position, and the control unit 3 here emits light of each LED 41r, 41g, 4 lb constituting the light source 41 of the image sensor unit 1. Adjust individually.
- each LED 41r, 41g, 41b is individually adjusted by correcting variations in the light emission efficiency and sensor sensitivity of each LED 41r, 41g, 41b, and RGB line output OS ( This is because the output levels of r), OS (g), and OS (b) are adapted to the input range VH of the AZD converter 35 to obtain image information with the optimum SZN ratio.
- a method of adjusting the light emission amount of each LED 41r, 41g, 41b for example, a method of adjusting the lighting intensity or lighting period of each LED 41r, 41g, 41b in the image information storage period TS is used.
- a predetermined lighting period TD is set in the lighting condition register 33a, and the white reference plate 5 installed on the upper surface of the platen glass 4 is read.
- the maximum value of the line output of each color in the sensor array 15 is Vrl, Vgl, Vbl
- the maximum value of the target output is VH
- the values TLr, TLg, Set TLb as shown in (Equation 1) to (Equation 3) below.
- TLr TD XVH / Vrl Equation (1)
- each LED 41r, 41g, and 41b is adjusted according to the lighting time, and the output levels of the RGB line outputs OS (r), OS (g), and OS (b) are equal to each other, and the AZD converter Fits 35 input ranges VH.
- reference data used by the shading corrector 36 that corrects the offset error and gain error included in the output signal of the sensor array 15 is acquired and stored in the memory 37.
- the offset correction data D is acquired with the light source 41 turned off, and stored in the memory 37.
- the lighting periods of the three LEDs 41r, 41g, and 41b constituting the light source 41 are respectively set to the lighting periods TLr, TLg, and TLb with the above-described light amount correction.
- the three LEDs 41r, 41g, and 41b are sequentially turned on during the set lighting periods TLr, TLg, and TLb, gain correction data Wr, Wg, and Wb are obtained and stored in the memory 37.
- control unit 3 drives the image sensor unit 1 and the displacement mute 2 to convert the optical information of the document sheet 7 into an electrical signal.
- the analog signal output by the image sensor unit 1 is converted into digital data by the AZD converter 35.
- the shading corrector 36 performs the following calculations (Equation 4) to (Equation 6) for each color line output Sr, Sg, Sb of the sensor array 15, for example. Is corrected, and standard line output [R], [G], [B] is obtained.
- the standard key line outputs [R], [G] and [B] subjected to the shading correction in this way are stored in the line memory 38. Then, the time delay of the image signal that has been color-separated line-sequentially is adjusted. Thereafter, the RGB standard output signals Ri, Gi, Bi corresponding to the same position on the original paper 7 are sequentially taken out, and the color space converter 39 performs color space conversion processing.
- FIG. 13 is a diagram for explaining color space conversion in this color space change. Here, color space conversion processing is performed using a 3 ⁇ 3 correction matrix M.
- the RGB standard key output signals Xi, Yi, and Zi are output in this way.
- the image data measured by the image input device is reproduced from the image output device (output device) such as a display.
- image input devices and image output devices have their own color space with light sources, filters, pigments, and so on. Therefore, in order to obtain the desired color reproduction by connecting the image input device and the image output device, it is necessary to perform signal processing in consideration of the difference in the color space.
- Image input device and image output device If there is a fixed one-to-one color space, there may be a single color space converter that connects each color space, but the input image data can be used for a variety of purposes. I cannot fix my tip.
- the image input device converts the image data in the color space unique to the image input device into a common standard color space independent of the device, and outputs it.
- the image data is reproduced by the image output device, the image data in the standard color space is converted into a color space unique to the image output device.
- a color space such as CIEXYZ or CIELAB is used as the standard color space for such conversion.
- the coefficients of the 3 ⁇ 3 correction matrix M included in the color space converter 39 described above are calculated, for example, from sensor signals for N color charts whose tristimulus values are known.
- TN is the tristimulus matrix for the N color target
- UN is the sensor output matrix for the N color target.
- the ISOZDIS 12641 IT8 color chart is known as the standard color chart used for color proofing.
- Patent Document 1 Japanese Patent Laid-Open No. 61-148959
- Patent Document 2 Japanese Patent Laid-Open No. 08-275006
- Patent Document 3 Japanese Patent Laid-Open No. 11-243492
- an image sensor unit used is used.
- the total spectral sensitivity of the sensor needs to be a linear combination with respect to the color matching functions constituting the standard color space.
- the LEDs 41r, 41g, and 41b are used as the light source 41, and color separation is performed by switching the lighting thereof. For this reason, the overall spectral sensitivity is almost
- Figure 14 shows the CIEXYZ color matching functions ⁇ ( ⁇ ), y ( ⁇ ), ⁇ ( ⁇ ) standardized at the peak, and the three RGB LEDs 41r, 41g, 411) emission spectrum 1: (e), g (l), b ().
- Typical values of the main wavelengths and half-value widths of the emission spectra r ( ⁇ ), g () and h () of the three RGB LEDs 41r, 41g and 41b used in the sensor array are as follows:
- the light emission spectrum of LED41r, 41g, and 411) has a half-value width of (e), g (l), b (e), and the corresponding color matching function ⁇ ( ⁇ ), ⁇ ( ⁇ ), and ⁇ ( ⁇ ) are narrower than the spectral width. Therefore, the color matching functions ⁇ ( ⁇ ), ⁇ ( ⁇ ), ⁇ () that constitute the standard color space are obtained only by combining the emission spectra r ( ⁇ ), g (l), b () of the LEDs 41r, 41g, 41b. It was difficult to approximate ⁇ ), and there was a problem that the colorimetric performance was good.
- FIG. 15 shows an xy chromaticity diagram representing a colorimetric error obtained by simulating a conventional image reading apparatus using LEDs 41r, 41g, and 41b.
- the white circle is the XYZ3 stimulus value of the IT8 target
- the black circle is the output of the image sensor unit 1 of the conventional image reader using LEDs 41r, 41g, 41b 3 Stimulus value.
- the positions of the white and black circles are misaligned, causing a color measurement error! / I can confirm that.
- the average color difference ⁇ obtained from the xy chromaticity diagram shown in FIG. 15 was “about 8”. In general, it is known that when this standard color difference ⁇ E is “3” or more, it is possible to identify a colorimetric error by the human eye. Accordingly, it can be said that the average color difference ⁇ E obtained from the XY chromaticity diagram shown in FIG. 15 is large enough to be recognized by humans.
- Patent Document 1 a method for changing a lighting condition of a light source to achieve a predetermined color reproduction has been studied. Also, by increasing the light source color, that is, the number of color separations, an attempt has been made to reduce the colorimetric error while using an LED having a narrow emission spectrum half-width as a light source (see Patent Documents 2 and 3). In Patent Document 2, a tri-stimulus value (tri-stim A method for improving the reproducibility of color information by converting to (ulus) is disclosed.
- the above-described problem will be described by taking as an example a configuration of an image sensor device in which color separation is performed into five colors using five color LEDs.
- the LEDs with five different emission wavelengths of the light source are connected by a circuit configuration similar to that shown in Fig. 9, and it is possible to control lighting of the five LEDs independently.
- Lc, Ld, and e the five LEDs provided as the light source 161 can be individually lit.
- the five LEDs are generated by control signals ⁇ La, ⁇ Lb, Lc, ⁇ ⁇ () Le generated according to the timing chart shown in FIG. Be controlled. That is, in the conventional general color separation method, as shown in FIG. 17, it can be easily imagined that five LEDs are sequentially emitted in time series and an image signal is obtained at each timing.
- the color space transformation 180 uses 3 ⁇ 5 correction matrix M from five types of color information Ai, Bi, Ci, Di, Ei, and 3 in the standard color space.
- An image signal converted into stimulus values (Xi, Yi, Zi) is obtained.
- the reading time is 5Z3 times (approximately 1.67) compared to the switching operation of the three color light sources. Times). Furthermore, as a system resource for the image reading device shown in Fig. 10, the amount of memory used for shading correction, line delay, or color conversion is also 5Z3 times (approximately 1. (67 times) Required. [0038]
- the present invention has been made in view of the above problems, and a feature of the present invention is to solve the above-mentioned drawbacks of the conventional examples.
- An object of the present invention is to reduce a colorimetric error as much as possible while suppressing an increase in reading time and an increase in memory capacity when reading an original.
- An image reading apparatus has the following configuration. That is,
- Light emission control means for controlling at least one of the light emission period and the light emission intensity of the three or more light emitting elements, and causing the light emitting elements to emit light at the same time or in different periods;
- Photoelectric conversion means for receiving and photoelectrically converting reflected light from the original obtained by emitting light from the plurality of light emitting elements toward the original in accordance with control by the light emission control means;
- Reading means for reading image information of the document based on the electrical signal photoelectrically converted by the photoelectric conversion means
- the photoelectric conversion means receives reflected light from the document in each of a plurality of accumulation periods in the main scanning direction,
- the light emission control means causes the plurality of light emitting elements to emit light under different conditions for each of a plurality of accumulation periods in the main scanning direction, and relative light emitted in at least one accumulation period.
- the ratio of the amount of light emitted is similar to the curve of one of the three color matching functions,
- the number of accumulation periods in the main scanning direction is less than or equal to the number of the plurality of light emitting elements.
- the present invention when reading an original, it is possible to reduce a colorimetric error while suppressing an increase in reading time and an increase in memory capacity.
- FIG. 1 is a schematic cross-sectional view illustrating a configuration example of an image reading apparatus according to Embodiment 1 of the present invention.
- FIG. 2 is a functional block diagram illustrating a functional configuration of the image reading apparatus according to Embodiment 1 of the present invention.
- FIG. 3 is a timing chart for explaining the driving operation of the image sensor unit during the reading operation of the original paper in the image reading device according to the first embodiment of the present invention.
- FIG. 4 is a block diagram showing a configuration example of a light source controller of the image reading apparatus according to Embodiment 1 of the present invention.
- FIG. 5C is a diagram showing an example of the characteristics of illumination light obtained by the image reading apparatus according to Embodiment 1 of the present invention.
- FIG. 6 is an XY chromaticity diagram showing colorimetric accuracy obtained by simulating the image reading apparatus according to Embodiment 1 of the present invention.
- FIG. 7 is a timing chart for explaining an example of the driving operation of the image sensor unit when the lighting time of the light source is time-divisioned in the image reading apparatus according to Embodiment 2 of the present invention.
- FIG. 8 is a cross-sectional view showing a configuration of a conventional image sensor unit.
- FIG. 9 is a diagram for explaining the arrangement of LEDs in a conventional image sensor unit.
- FIG. 10 is a block diagram showing a configuration of a conventional image reading apparatus.
- FIG. 11 is a timing chart for explaining the driving operation of the image sensor unit when there are three LEDs in the conventional image reading apparatus.
- FIG. 12 is a diagram showing a configuration of a light source controller when there are three LEDs in a conventional image reading apparatus.
- FIG. 14 is a diagram showing a relationship between a color matching function and an emission spectrum of an LED in a conventional image reading apparatus.
- FIG. 15 is an xy chromaticity diagram showing a colorimetric error obtained by simulating an image reading apparatus in the case of five LEDs in a conventional image reading apparatus.
- FIG. 16 is a diagram showing a configuration of a light source controller when there are five LEDs in a conventional image reading apparatus.
- FIG. 17 is a timing chart for explaining the driving operation of the image sensor unit when there are five LEDs in the conventional image reading apparatus.
- FIG. 18 is a block diagram showing a configuration of a color space corrector in the case of five LEDs in a conventional image reading apparatus.
- FIG. 19 is a schematic cross-sectional view illustrating the configuration of a conventional image reading apparatus.
- FIG. 1 is a schematic cross-sectional view for explaining the configuration of an image reading apparatus according to an embodiment of the present invention.
- the image reading device 6 according to the present embodiment is different from the conventional image reading device shown in FIG. 19 in the configuration of the image sensor unit and the control unit. Therefore, in the following description of the embodiment, the same parts as those of the conventional image reading apparatus are denoted by the same reference numerals as those shown in FIGS. 8 to 19 and their detailed description is omitted.
- the image reading apparatus 6 can be used for a scanner, a color facsimile, or a complex machine of these, and can also be used for an image input unit of a color copying machine.
- an image reading apparatus in which the image sensor unit 10 includes five LEDs 1 la, l ib, 11 c, 1 Id, and l ie (FIG. 4) having different emission wavelengths as light sources is provided. An example will be described.
- the five LEDs lla to lle include individual drive terminals for each light emitting element, and are configured to be able to light independently.
- the case where there are five LEDs will be described as an example. However, as will be described later, it is preferable that the number of LEDs constituting the light source is large.
- the image sensor unit 10 of the present embodiment is a CIS (contact image sensor) having the same configuration as that shown in FIG.
- the image reading apparatus 6 of the present embodiment shown in FIG. 1 will be briefly described by taking a flat bed type image reading apparatus as an example.
- the main part of the image reading device 6 is an image sensor unit 10, which is provided with a displacement unit 2 for changing the illumination reading position of the original paper 7.
- the document sheet 7 is fixed on the platen glass 4, and the image sensor unit 10 moves in the sub-scanning direction.
- the displacement unit 2 continuously changes the relative position of the image sensor unit 10. Therefore, the image information detected by the sensor array 15 is different for each position of the image sensor unit 10.
- the image reading device 6 according to the present embodiment performs a position correction line memory 38 (FIG. 2) in order to reproduce the information at the same position on the original paper 7 when scanning for three colors of RGB. ).
- CMOS type light receiving element As the photoelectric conversion unit of the sensor array 15 of the image sensor unit 10, there are generally a CMOS type light receiving element and a CCD type light receiving element.
- an image sensor unit 10 is configured by using multi-colored LEDs as a light source, and the original paper 7 is illuminated using three types of illumination light, and the reflected light is reflected. It is received by the light receiving element of sensor array 15. Therefore, the light receiving element only photoelectrically converts one-color image information in any image information accumulation period TS. Therefore, in the image reading device 6 according to the present embodiment, any of a CMOS type light receiving element and a CCD type light receiving element can be used as these light receiving elements.
- FIG. 2 is a functional block diagram showing a functional configuration of the image reading apparatus 6 according to the present embodiment.
- the image sensor unit 10 scans the entire original sheet 7 while changing the reading position of the original sheet 7 by the displacement unit 2 according to the control of the displacement unit controller 32 provided in the control unit 30.
- the light source control port The light source 23 provides the light source 11 in the image sensor unit 10 with a light source drive signal (drive signal) corresponding to the lighting conditions of the light source 11, that is, the light emission intensity and the light emission period of the LEDs 11.
- FIG. 3 is a timing chart for explaining an example of the driving operation of the image sensor unit 10 during the reading operation of the original paper 7 in the image reading apparatus according to the first embodiment.
- TC indicates an accumulation period of image information on one scanning line.
- the sensor array 15 constituting the image sensor unit 10 integrates (accumulates) the image signal in the integration period (accumulation period) TS1, TS2, TS3 of the image signal of 3 cycles. That is, in Embodiment 1, reading in the main scanning direction is performed three times.
- the light source controller shown in FIG. 2 23 power and LED1 la to: L ie, the horse motion signal ⁇ La, Lb, Lc, Ld , ⁇ Le force is output at the timing shown in Fig. 3, respectively. That is, provided in the light source controller 23 shown in FIG. 4, the pulse generator 23b generates the drive signals ⁇ La to ⁇ Le according to the values set in the lighting condition register 23a. These drive signals ⁇ La to ⁇ Le are supplied to the switching circuit corresponding to each LED in the lighting circuit 23c, and drive the LEDs 11 to 11 constituting the light source 11.
- each LED 11a to 11e can be driven with three types of lighting patterns with different amounts of light and lighting time by driving each LED according to the lighting conditions. That is, the lighting patterns of LEDs 1 to 1 can be made different in each integration period (cycle) TSl, TS2 and TS3.
- the three lighting patterns with different emission ratios for each LEDl la to lle are the three color matching functions expressed in the standard color space such as the emission spectral power of CIEXYZ.
- the three types of lighting patterns that change the light emission ratio of each LEDl la to l le are the relative light amounts of the light generated from LED 1 la to L le Is determined to have an intensity ratio that approximates three types of color matching functions expressed in a standard color space such as CIEXYZ.
- the control unit 30 drives the displacement unit 2 to move the image sensor unit 10 to the position of the white reference plate 5 installed on the document supporting glass 4.
- the white reference plate 5 should have a neutral color with a flat spectral reflectance.
- the five LEDs lla to lle are lit independently to illuminate the white reference plate 5, and the lighting time TLWn until the output of the sensor 15 reaches a predetermined value is measured.
- five LEDs lla to lle are used as light sources, and the measured lighting times TLWn of the five LEDs lla to lle are respectively TLWa, TLWb, TLWc, TLWd, and TLW e.
- a predetermined lighting period TD is set in the lighting condition register 23a to light each LED. Then, the light of each LED power reads the reflected light reflected from the white reference plate 5. At this time, assuming that the maximum value of the line output of each color of the image sensor unit 10 is Val, Vbl, Vcl, Vdl, Vel, and the maximum value of the target line output is VH, LEDl of each color:
- the lighting periods TLWa to TLWe of the white reference plate 5 can be obtained by the following (Expression 8) to (Expression 12), respectively.
- TLWa: TD XVH / Val (8)
- TLWb TD XVH / Vbl (9)
- TLWd TD XVH / Vdl Equation (11)
- the 3 x 5 color space used in the color space variation ⁇ shown in Fig. 18 It is possible to use the coefficients (all, al2, a34, a35) of the correction matrix M. For example, 5 color 1 ⁇ : 011 & ⁇ 1 ⁇ are turned on one by one and 5 light source switching operations are performed to read and read N color charts with known tristimulus values. Sen for each color chart The correction matrix M can be calculated from the signal.
- the lighting condition register values TLXa to TLZe of each LEDlla to lle set in the lighting condition register 23a are calculated by the following equations (14) to (28).
- TLXa: TLWaXall (14)
- TLYd TLWdXa24 ... Formula (24)
- the color space conversion process using the 3 ⁇ 5 correction matrix M is performed after the processing circuit of the image signal output from the sensor array 15.
- illumination light that approximates three types of color matching functions is created on the light source side by driving multicolor light sources (LEDlla to lle).
- signal processing times such as scanners The road can be processed in the same way as when using three conventional RGB light sources.
- the line memory 38 necessary for storing data required for these corrections or the like only needs to have the same capacity for three colors as the conventional one.
- the first embodiment it is possible to use the reading scanning method similar to the switching operation of the three color light sources in spite of the switching operation of the five color light sources.
- multiple light sources LED1 la ⁇ : Lie
- the overall illumination intensity is also increased, and the reading speed is faster than the conventional method of illuminating the three colors of RGB. It is possible to increase the speed.
- FIG. 5A to FIG. 5C are diagrams showing an example of characteristics of illumination light obtained by the image reading device 6 according to the first embodiment.
- the emission spectra 51a to 51c of three kinds of lighting patterns formed by appropriately mixing the amounts of light from the five LEDs lla to lle, and their CIE color matching functions ⁇ ( ⁇ ), ⁇ Curves 52a to 52c of ( ⁇ ) and ⁇ ( ⁇ ) are shown.
- the curves 52a to 52c of the color matching functions are discretely well approximated by the emission spectra 51a to 51c.
- each of the LEDs lla to lle performs a lighting operation so as to obtain an intensity corresponding to the relative intensity of the color matching function.
- the color information of the image sensor unit 10 is more abundant and the color reproducibility is improved in each stage compared to the conventional case where only one LED is illuminated for each color.
- the color space modulator 39 is not necessary as compared with the conventional image reading apparatus shown in FIG. Become. In this way, it is possible to directly read the modulated color information without converting the output signal into tristimulus values by color space conversion processing. Furthermore, the light emission timing of each LEDl la to lle is heavy. Therefore, the image information storage period may be set equal to or slightly longer than the maximum light emission time of LEDs lla to lle. Therefore, compared with the conventional image reading apparatus shown in FIG. 10, the reading time of the image information for one line portion can be shortened.
- the spectra 51a to 51c are approximated to three types of color matching functions (for example, CIE color matching functions 52a to 52c) expressed in a standard color space such as CIEXYZ. That is, the light emission spacers 51a to 51c approximated to the three types of color matching functions are generated on the light source side in the integration periods (accumulation periods) TS1, TS2, and TS3 of the image signal.
- LED1 la when determining three types of lighting patterns in the integration period (accumulation period) TS1, TS2, TS3 of the image signal, LED1 la to: Lle light quantity (intensity) and light emission Both periods are different for each of the three lighting patterns, but this is not necessary. That is, the emission spectrum formed using LEDl la ⁇ l le (for example, if the emission spectrum 51 a to 51 c) is approximated to three types of color matching functions (for example, CIE color matching functions 52 a to 52 c), only one of the light amounts and lighting times of LEDlla to lle is calculated. , You may make it differ for every three kinds of lighting patterns.
- image signals are integrated (accumulated) in three integration periods (accumulation periods) TS1, TS2, TS3 (that is, reading in the main scanning direction is performed three times).
- the number of integration periods is not limited to “3”. That is, if the emission spectrum formed using LEDlla ⁇ : Lie is approximated to three color matching functions, even if four or more LED light sources are used, The number can be 3 or more and less than the number of LEDs. Specifically, in the present embodiment, since five LEDs 1 la to l le are used, the number of image signal integration periods may be set to “4” instead of “3”.
- any of the three types of color matching functions can be used. Good.
- it may be the CIE color matching function as described above, or the three types of spectral curves (color matching function) of the CIE standard observer.
- the emission spectrum formed by the LEDlla to lle emission operation (for example, emission spectra 51a to 51c) is converted into three types of color matching curves (for example, CIE color matching functions ⁇ ( ⁇ ), ⁇ ( ⁇ ), The approximation of ⁇ ( ⁇ ) curves 52a to 52c) is to make the emission spectrum formed by the LEDlla to lle emission operation positively close to the three color matching functions. It is a concept that includes controlling the operation. [Modification]
- the mixing ratio of LED1 la to 1 le corresponding to the color matching function x ( ⁇ ) is x): ⁇ (): x ( ⁇ ): ⁇ ( ⁇ ): ⁇ ( ⁇ )
- the mixing ratio of LEDlla to lle corresponding to the color matching function y () is set to y (a): y (i8 ): y ( y ): y (6): LED set to y (s) and corresponding to color matching function ⁇ ( ⁇ )
- the mixing ratio of 11 & ⁇ 1 ⁇ is set to 2 (0;): 2 (
- the color matching functions ⁇ ( ⁇ ), y ( ⁇ ), and ⁇ ( ⁇ ) can be approximated by synthesizing the emission spectra of the five LEDlla to lle.
- each color LED1 la ⁇ drive signals for turning on and off Lie ⁇ La ⁇ ⁇ Le Is supplied to the lighting circuit 23c.
- the lighting circuit 23c is configured by using a predetermined power source for lighting each LEDlla to lle and a switching circuit (transistor) that operates in synchronization with the pulse generator 23b.
- LED1 la ⁇ L le should be lit during the on-period.
- the spectral reflectance characteristics of the dyes and pigments used in the manuscript paper 7 are comparatively gentle spectral curves on the wavelength axis, and the amount of change with respect to the wavelength is small. Even a discrete approximation can provide practically sufficient colorimetric performance.
- FIG. 6 is an XY chromaticity diagram showing the colorimetric accuracy obtained by simulating the image reading apparatus of the first embodiment.
- white circles are the XYZ3 stimulus values of the IT8 target
- black circles are the tristimulus values that are the output of the image sensor unit 10 of the image reading apparatus according to the first embodiment.
- the xy chromaticity diagram shown in Fig. 6 shows that the error is reduced for any color series compared to the xy chromaticity diagram shown in Fig. 15.
- the average color difference ⁇ obtained from the xy chromaticity diagram shown in Fig. 6 has been reduced to about 2, and the color difference cannot be recognized with the naked eye.
- the wavelength characteristics of the spectral reflectances of the dyes and pigments generally used for the original paper 7 are little changed, so that practically sufficient colorimetric accuracy can be obtained with 5 to 6 colors. For this reason, the case of having five light emitting elements has been described in the first embodiment.
- the effect of the first embodiment can arbitrarily determine which color of LED (light emitting element) to be used as the number of LEDs constituting the light source increases. In other words, the color measurement accuracy improves as the number of colors increases, but the system resources such as reading speed and memory do not increase even when the number of colors is increased, compared to the conventional method of switching the light source for the number of colors. ,.
- the second embodiment is different from the first embodiment described above only in the timing of turning on each of the LEDs 1-lle. Therefore, in the description of the second embodiment below, the same parts as those of the conventional image reading device and the image reading device 6 of the first embodiment are attached to FIGS. 1 to 6 and FIGS. The same reference numerals are used and detailed description is omitted.
- the photoelectric change capability of the sensor array 15 is determined by the integration period TS1, It may be done at any time in TS2 and TS3. For example, the lighting time of the light source 11 may be divided in time.
- FIG. 7 is a timing chart for explaining an example of the drive operation of the image sensor unit 10 when the lighting time of the light source 11 is time-divided in the second embodiment.
- the feature of the second embodiment is that the timings at which the LEDs 1la to lle in the integration periods TS1, TS2 and TS3 of the image signal are lit are overlapped! / That's it!
- the advantage of this method is that the drive current supplied to each LEDl la ⁇ l le is temporally distributed, so that the instantaneous current flowing to each LED1 la ⁇ : Lie is reduced and the load on the power supply circuit is reduced. It is to be reduced.
- the timing for lighting each LEDl la to l le is time-series, the next LED 1 la to l le is turned on in synchronization with the turn-off timing of one color LE Dl la to l le. Therefore, the configuration of the control circuit can be further simplified.
- this method takes the timing of lighting the LEDs l la to l le for each color separately, the integration periods TS1, TS2, TS3 are: This is longer than that of the first embodiment described above.
- the image information storage period TC in one scanning period tends to be long, which has a drawback.
- the program code of the software itself realizes the functions of the above-described embodiments, and the program code itself and means for supplying the program code to the computer, for example,
- a recording medium storing the program code to be used constitutes the present invention.
- a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used as a recording medium for storing the program code.
- the function expansion board or function expansion unit is based on the instruction of the program code. It goes without saying that the present invention also includes a case where the CPU or the like provided in the above performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.
- the image reading apparatus of the present invention can be applied to, for example, a document reading apparatus, and can also be used in a scan color facsimile, a copying machine, or a complex machine thereof. It can also be used for an image input unit of a color copying machine.
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- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Facsimile Scanning Arrangements (AREA)
- Facsimile Heads (AREA)
- Control Of Exposure In Printing And Copying (AREA)
- Facsimile Image Signal Circuits (AREA)
- Color Image Communication Systems (AREA)
Abstract
Description
Claims
Priority Applications (2)
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US11/572,786 US7476847B2 (en) | 2004-07-29 | 2005-07-25 | Adaptive image reading apparatus and control method of the apparatus |
JP2006529318A JPWO2006011450A1 (ja) | 2004-07-29 | 2005-07-25 | 画像読取装置及び画像読取方法 |
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JP2004221259 | 2004-07-29 | ||
JP2004-221259 | 2004-07-29 | ||
JP2005167464 | 2005-06-07 | ||
JP2005-167464 | 2005-06-07 |
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WO2006011450A1 true WO2006011450A1 (ja) | 2006-02-02 |
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PCT/JP2005/013583 WO2006011450A1 (ja) | 2004-07-29 | 2005-07-25 | 画像読取装置及び画像読取方法 |
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US (1) | US7476847B2 (ja) |
JP (1) | JPWO2006011450A1 (ja) |
TW (1) | TWI272832B (ja) |
WO (1) | WO2006011450A1 (ja) |
Cited By (3)
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US8184245B2 (en) | 2008-03-31 | 2012-05-22 | Fujifilm Corporation | Optical compensation film for VA-mode liquid crystal display device and VA-mode liquid crystal display device |
US8493314B2 (en) | 2007-06-12 | 2013-07-23 | Fujifilm Corporation | Backlight unit and liquid crystal display |
CN112147951A (zh) * | 2020-09-28 | 2020-12-29 | 沈机(上海)智能系统研发设计有限公司 | 机加工设备热误差补偿方法及其装置、系统、介质、终端 |
Families Citing this family (9)
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WO2005088955A1 (ja) * | 2004-03-16 | 2005-09-22 | Canon Components, Inc. | カラーイメージセンサユニット及び前記センサユニットを用いた画像読み取り装置及びその制御方法 |
US7746517B2 (en) * | 2007-01-25 | 2010-06-29 | Lexmark International, Inc. | Image illumination and capture in a scanning device |
JP2010161719A (ja) * | 2009-01-09 | 2010-07-22 | Nec Engineering Ltd | 画像読取装置 |
TW201039609A (en) * | 2009-04-29 | 2010-11-01 | jian-bo Wang | Mobile phone with integrated functions of receiving and sending fax |
KR101628238B1 (ko) * | 2009-12-21 | 2016-06-21 | 삼성전자주식회사 | 화상을 독취하는 장치 및 방법 |
IT1397417B1 (it) * | 2010-01-12 | 2013-01-10 | Colagrande | Dispositivo di illuminazione per la scansione digitale di immagini con configurazioni variabili delle angolazioni della luce. |
IT1400521B1 (it) | 2010-05-13 | 2013-06-11 | Colagrande | Metodo per la scansione digitale di immagini con modulazione dinamica dell'illuminazione durante la scansione |
JP2014071182A (ja) * | 2012-09-28 | 2014-04-21 | Canon Inc | 画像形成装置 |
KR101561618B1 (ko) * | 2014-02-19 | 2015-10-30 | 안동대학교 산학협력단 | 단색 스캐닝 카메라에서의 컬러 영상 획득 시스템 및 방법 |
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- 2005-07-25 WO PCT/JP2005/013583 patent/WO2006011450A1/ja active Application Filing
- 2005-07-25 US US11/572,786 patent/US7476847B2/en not_active Expired - Fee Related
- 2005-07-25 JP JP2006529318A patent/JPWO2006011450A1/ja active Pending
- 2005-07-28 TW TW094125639A patent/TWI272832B/zh not_active IP Right Cessation
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US8493314B2 (en) | 2007-06-12 | 2013-07-23 | Fujifilm Corporation | Backlight unit and liquid crystal display |
US8184245B2 (en) | 2008-03-31 | 2012-05-22 | Fujifilm Corporation | Optical compensation film for VA-mode liquid crystal display device and VA-mode liquid crystal display device |
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CN112147951A (zh) * | 2020-09-28 | 2020-12-29 | 沈机(上海)智能系统研发设计有限公司 | 机加工设备热误差补偿方法及其装置、系统、介质、终端 |
CN112147951B (zh) * | 2020-09-28 | 2022-09-30 | 沈机(上海)智能系统研发设计有限公司 | 机加工设备热误差补偿方法及其装置、系统、介质、终端 |
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JPWO2006011450A1 (ja) | 2008-07-31 |
US20080029687A1 (en) | 2008-02-07 |
TWI272832B (en) | 2007-02-01 |
TW200608766A (en) | 2006-03-01 |
US7476847B2 (en) | 2009-01-13 |
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