JP4586812B2 - Image reading apparatus and method thereof - Google Patents

Description

  The present invention relates to an image reading apparatus and a method thereof.

2. Description of the Related Art Conventionally, as an image reading apparatus, when an object to be read is an image (for example, a negative) containing many dark areas with small gradations, the charges of red (R), green (G), and blue (B) image sensors. The accumulation time is set to a predetermined ratio, and the reading sensor is driven to accumulate charges based on this ratio to obtain a sufficiently large output value for each color, thereby amplifying the output value later by gamma correction or the like. There has been proposed one that suppresses the influence of noise that occurs when the image is read and suppresses the deterioration of the read image quality (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2002-77545

  By the way, in general, in an image reading apparatus, as an image reading process, there is a series of processes for accumulating charges, reading the accumulated charges, and generating an image from the read charges. Since the reading sensor may be driven using any one of the accumulation intervals, there is a predetermined limitation in changing the accumulation interval for accumulating charges in the reading sensor. For example, the accumulation interval may not be freely changed when the amount of light from the light source that irradiates the reading target is large. Here, in the apparatus of Patent Document 1, light irradiation is not considered, and when the accumulation time of each color reading sensor is changed, the ratio of irradiating light to each color reading sensor is shifted. It has been desired to prevent this.

  The present invention has been made in view of such a problem, and prevents a predetermined ratio of irradiated light in each element array from deviating when the accumulation interval of each element array is set to a predetermined ratio. Another object of the present invention is to provide an image reading apparatus and a method thereof. Another object of the present invention is to provide an image reading apparatus and method that can further reduce the time required for the reading process of the reading target.

  The present invention adopts the following means in order to achieve at least one of the above objects.

The image reading apparatus of the present invention includes:
Irradiating means for irradiating the reading object with white light;
The first element array having a plurality of first photoelectric conversion elements that can detect the amount of light and photoelectrically convert and accumulate charges, and the second element array and the photoelectric elements that have a plurality of second photoelectric conversion elements that photoelectrically convert and accumulate charges. Image reading means comprising one or more third element arrays each having a plurality of third photoelectric conversion elements that convert and store charges;
Based on the light amount of the irradiation means detected by the image reading means, a first irradiation time to the first element row, a second irradiation time to the second element row, and a third to the third element row. An irradiation time setting means for setting the irradiation time;
Based on the set irradiation time, the first accumulation interval, which is an interval from the start of accumulation of charges in the photoelectric conversion elements of the first element array to the reading of the accumulated charges, and the photoelectric conversion of the second element array A second accumulation interval, which is an interval from the start of accumulation of charge in the element to reading out the accumulated charge, and an interval from the start of accumulation of charge in the photoelectric conversion elements of the third element array to the readout of the accumulated charge. Accumulation interval setting means for setting at least one of the certain third accumulation intervals as a different interval and setting the respective accumulation intervals so that the first accumulation interval, the second accumulation interval, and the third accumulation interval have a predetermined ratio. When,
When the set irradiation time is shorter than a predetermined reference time determined based on the storage interval of the element array corresponding to the irradiation time, the predetermined ratio of the storage interval, the first irradiation time, and the second irradiation time Based on the third irradiation time and the third irradiation time, a unit pulse time common to the respective element rows and a pulse number which is the number of irradiation of light of the unit pulse time to each of the element rows are set in the respective element rows. Pulse setting means for
Based on the set accumulation interval, the image reading means is controlled to start accumulating charges in the photoelectric conversion elements of the respective element arrays and read the accumulated charges, and the set value is set during the accumulation interval. Control means for controlling the irradiating means to irradiate light to each of the element rows based on the unit pulse time and the number of pulses,
It is equipped with.

  In this image reading apparatus, a first irradiation time to the first element row, a second irradiation time to the second element row, and a third irradiation time to the third element row are respectively set based on the detected light amount. Then, based on the set irradiation time, the first accumulation interval and the second accumulation interval of the second element row, which are intervals from the start of charge accumulation to the photoelectric conversion elements of the first element row until the accumulated charge is read out And at least one of the third storage intervals of the third element array is set to a different interval, and the respective storage intervals are set so that the first storage interval, the second storage interval, and the third storage interval have a predetermined ratio. When the set irradiation time is shorter than a predetermined reference time determined based on the storage interval of the element array corresponding to this irradiation time, the predetermined ratio of the storage interval, the first irradiation time, the second irradiation time, and the third Unit pulse common to each element array based on irradiation time Set the number of pulses, which is the number of light beams emitted during unit pulse time to each element row, for each element row, and start accumulating charges on the photoelectric conversion elements of each element row based on the accumulation interval Then, the accumulated electric charges are read out, and light is irradiated to each element row based on the unit pulse time and the number of pulses during the accumulation interval. As described above, since light is emitted to each element row for the number of pulses determined for each element row with a unit pulse time common to each element row, accumulation of charges caused by rising and falling of light irradiation is performed. It is possible to suppress the deviation. Therefore, it is possible to prevent the predetermined ratio of the light emitted from each element row from deviating. Here, the “predetermined reference time determined based on the accumulation interval” may be set to a time such that the read image data has an appropriate image quality, or may be the same time as the accumulation interval. Alternatively, a predetermined ratio (for example, 80% or 90%) of the accumulation interval may be used. In addition, “irradiate light to the element array” may be to irradiate light from the irradiation unit to the element array through the reading target, or to irradiate light from the irradiation unit to the element array without passing through the reading target. It is good also as what to do. In addition, “pulse irradiation” may be performed such that light irradiation for a unit pulse time is performed over the number of pulses so that light irradiation is performed at equal intervals during the accumulation interval, or light irradiation is performed during the accumulation interval. Irradiation of light of unit pulse time may be performed over the number of pulses so as not to be equally spaced.

  In the image reading apparatus of the present invention, the accumulation interval setting means sets the first accumulation interval to the longest accumulation interval, sets the second accumulation interval to the accumulation interval next to the first accumulation interval, The third accumulation interval is set to the shortest accumulation interval, and the control means includes the second accumulation interval between the first accumulation intervals and the third accumulation interval between the second accumulation intervals. The irradiation unit may be controlled so that the pulse irradiation is performed in the state. By so doing, charge accumulation in the first, second, and third element arrays is performed redundantly, so that the time required for the entire reading process can be further shortened. At this time, the control means performs pulse irradiation to the first element array during the first accumulation interval, and subsequently to the first and second element arrays during the first and second accumulation intervals. Pulse irradiation to the first, second and third element arrays during the first, second and third accumulation intervals, and then the first, second and third elements. The irradiation unit and the image reading unit may be controlled so as to read out the accumulated charges from the column at the same timing. By doing so, the timing for reading out the accumulated charge is the same for each element row, so that the accumulated charge can be easily read out. At this time, the accumulation interval setting means is configured such that the first accumulation interval, the second accumulation interval, and the third accumulation interval are in a ratio of X: Y: Z (X> Y ≧ Z and X, Y, and Z are positive integers). ), And the pulse setting means sets the number of pulses of the first element row to X × n times (n is an integer of 1 or more), and sets the number of pulses of the second element row to Y. Xn times, the number of pulses of the third element array is set to Z * n times, and the control means is configured to control the first element during the first accumulation interval and before reaching the second and third accumulation intervals. The column is irradiated with (X−Y) × n pulses of the set unit pulse time, and then the first and the second during the first and second accumulation intervals and before reaching the third accumulation interval. The second element array is irradiated with (YZ) × n pulses of the set unit pulse time, and then the first, second and second pulses are performed. During the third accumulation interval, the first, second, and third element arrays are irradiated with the set unit pulse time z × n times, and the same from the first, second, and third element arrays. The irradiation unit and the image reading unit may be controlled so as to read out the accumulated charges at a timing. At this time, the number of times n = 1 may be set. By doing so, the unit pulse time can be made the longest, so that the deviation of the light quantity due to the rising and falling of the light irradiation can be most suppressed.

  In the image reading apparatus of the present invention, the accumulation interval setting means sets the respective accumulation intervals in a reference process for reading a predetermined white reference for calibration of the image reading means before the reading process of the reading object, and Each accumulation interval in the reading process to be read is set, and the control unit controls the image reading unit based on the accumulation interval set for the reference process, and the pulse irradiation is performed during the accumulation interval. The reference processing is executed by controlling the irradiating means, and then the image reading means is controlled based on the accumulation interval set for the reading process of the reading object, and during the accumulation interval, etc. It is good also as what performs the reading process of reading object by controlling the said irradiation means so that the said pulse irradiation may be carried out at intervals. In this way, since pulse irradiation is performed at equal intervals at least during the reading process of the reading target, a reading result with a more uniform image quality can be obtained as compared with a case where pulse irradiation is performed at different intervals during the reading process.

  In the image reading apparatus of the present invention, the accumulation interval setting means sets each accumulation interval in the reference process to be the predetermined ratio, and sets each accumulation interval in the reading process to be read as the same interval. It is good also as what sets so that it may become. In this way, each element array is calibrated by setting the accumulation interval of each element array to a predetermined ratio during the reference process, and each accumulation interval is the same in the reading process. The reading process can be made relatively simple. Further, in this way, in the reading process of the reading object, the reading of the charge of the other element row is not performed during the accumulation of one of the element rows, so the accumulation of the charge and the reading of the accumulated charge overlap. Therefore, the time required for the entire reading process can be further shortened.

  In the image reading apparatus of the present invention, when the reading target is a suppressed document in which transmission of a specific color is suppressed, the accumulation interval setting unit is configured to determine the first accumulation interval and the first interval based on the set irradiation time. Each accumulation interval is set such that at least one of the two accumulation intervals and the third accumulation interval is different, and the first accumulation interval, the second accumulation interval, and the third accumulation interval have a predetermined ratio. It may be a thing. When the suppressed document is read, at least one of the first accumulation interval, the second accumulation interval, and the third accumulation interval is often set to a different interval, and the significance of applying the present invention is high. Here, the “suppressed original” may be, for example, a negative transparent original.

  In addition, the irradiation time setting means sets the first, second, and third irradiation times based on the image quality of the read image when setting the first, second, and third irradiation times based on the light amount of the irradiation means detected by the image reading means. It is also possible to set an irradiation time such that the detected light quantity of the irradiation means falls within a predetermined appropriate range. The accumulation interval setting means may read any one of a plurality of accumulation intervals stored in advance in the storage means and set the accumulation interval of the first, second, and third element arrays.

The image reading method of the present invention includes:
Irradiation means for irradiating the reading target with white light, and a second element that can detect the amount of light and photoelectrically convert and store the charge by photoelectric conversion with a first element array having a plurality of first photoelectric conversion elements that store the charge. An image reading apparatus comprising: a second element array having a plurality of photoelectric conversion elements; and an image reading unit including at least one third element array having a plurality of third photoelectric conversion elements that perform photoelectric conversion and store charges. An image reading method using
(A) Based on the light amount of the irradiation unit detected by the image reading unit, the first irradiation time to the first element row, the second irradiation time to the second element row, and the third element row Respectively setting the third irradiation time of
(B) based on the irradiation time set in the step (a), a first accumulation interval that is an interval from the start of accumulation of charges to the photoelectric conversion elements of the first element array until the accumulated charges are read out; The second accumulation interval, which is an interval from the start of charge accumulation to the photoelectric conversion elements of the second element row to the reading of the accumulated charge, and the accumulation from the start of charge accumulation to the photoelectric conversion elements of the third element row Each accumulation is performed so that at least one of the third accumulation intervals, which is an interval until the read charge is read out, is a different interval, and the first accumulation interval, the second accumulation interval, and the third accumulation interval have a predetermined ratio. A step for setting the interval;
(C) When the irradiation time set in step (a) is shorter than a predetermined reference time determined based on the storage interval of the element array corresponding to the irradiation time, the predetermined ratio of the storage intervals and the first Based on the irradiation time, the second irradiation time, and the third irradiation time, the unit pulse time that is common to each element row and the number of pulses that is the number of irradiation of light of the unit pulse time to each element row Setting each of the element rows;
(D) based on the accumulation interval set in the step (b), controlling the image reading means to start accumulating charges in the photoelectric conversion elements of the respective element arrays and reading the accumulated charges, Controlling the irradiating means to irradiate light to the respective element rows based on the unit pulse time and the pulse number set in the step (c) during the accumulation interval;
May be included.

  In this image reading method, the first irradiation time to the first element row, the second irradiation time to the second element row, and the third irradiation time to the third element row are set based on the detected light amount. Then, based on the set irradiation time, the first accumulation interval and the second accumulation interval of the second element row, which are intervals from the start of charge accumulation to the photoelectric conversion elements of the first element row until the accumulated charge is read out And at least one of the third storage intervals of the third element array is set to a different interval, and the respective storage intervals are set so that the first storage interval, the second storage interval, and the third storage interval have a predetermined ratio. When the set irradiation time is shorter than a predetermined reference time determined based on the accumulation interval corresponding to this irradiation time, the predetermined ratio of the accumulation interval, the first irradiation time, the second irradiation time, and the third irradiation time Unit pulse time and common to each element array based on The number of pulses, which is the number of light pulses emitted per unit pulse to each element row, is set for each element row, and charge accumulation to the photoelectric conversion elements of each element row is started based on the accumulation interval. The accumulated electric charges are read out, and light is irradiated to each element array based on the unit pulse time and the number of pulses during the accumulation interval. As described above, since light is emitted to each element row with the number of pulses determined for each element row with a unit pulse time common to each element row, accumulation of charges caused by rising and falling of light irradiation is performed. Can be suppressed. Therefore, it is possible to prevent the predetermined ratio of the light emitted from each element row from deviating. In this image reading method, various aspects of the above-described image reading apparatus may be adopted, and steps for realizing each function of the above-described image reading apparatus may be added.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an outline of a configuration of a scanner device 10 according to an embodiment of the present invention. As shown in FIG. 1, the scanner device 10 of the present embodiment includes a carriage 30 that reads an image of a read original M placed on a reading surface 12 that is a glass plate, a control unit 20 that controls the entire device, A transparent original light source 32 is provided above the read original M and used when reading the transparent original, and a drive motor 39 that moves the carriage 30 is provided.

  The carriage 30 is disposed below the read original M, and includes a reflective original light source 31 that irradiates light on the original placed on the reading surface 12, and a mirror 33 and a condenser lens that reflects or transmits light reflected from the original. And an image sensor 36 that reads an image by receiving the image through 34. The reflection original light source 31 is configured so that light from one or a plurality of white LEDs is linearly irradiated to the reading surface 12. In addition, it is good also as what irradiates white light by red LED, green LED, blue LED, etc. The transmissive original light source 32 has the same configuration as the reflective original light source 31. The image sensor 36 includes a first element array 36R provided with a plurality of imaging elements and outputting a red (R) signal; a second element array 36G provided with a plurality of imaging elements and outputting a green (G) signal; A plurality of image sensors are provided, and a third element array 36B that outputs a blue (B) signal is provided. The first element row 36R is a photoelectric conversion element corresponding to a pixel, and converts the light when exposed to charges into a plurality of photodiodes 41, and the charges received from the photodiodes formed for each photodiode. And a plurality of CCDs 42 capable of transferring. The second element array 36G includes a photodiode 43 and a CCD 44, and the third element array 36B includes a photodiode 45 and a CCD 46, and is configured in the same manner as the first element array 36R. . In the carriage 30, a carriage belt 38 is driven by a drive motor 39 between a drive motor 39 attached to one end of the housing of the scanner device 10 and a driven roller 38 a attached to the other end of the housing. Accordingly, it moves in the carriage movement direction (sub-scanning direction). Although a CCD image sensor is exemplified here as the image sensor 36, a CMOS type image sensor may be adopted. Further, the image sensor 36 in which the element rows 36R, 36G, and 36B for each color are arranged one by one in the main scanning direction is illustrated, but two or more element rows for each color may be arranged.

  The control unit 20 includes a main controller 21 that controls the entire apparatus, a CCD controller 25 that drives and controls the image sensor 36, and a timing generator (TG) that outputs to the image sensor 36 the start timing of various operations of the image sensor 36. ) 26, an analog front end (AFE) 27 that amplifies the electrical signal output from the image sensor 36 and converts it into a digital signal, and digital image data by executing predetermined processing such as gamma correction on the signal input from the AFE 27. And an interface (I / F) 29 that can be connected to an external device such as a user personal computer (PC) 50. The main controller 21 is configured as a microprocessor centered on a CPU 22, and includes a ROM 23 that stores processing programs and various tables, a RAM 24 that temporarily stores data, a light source 31 for reflective originals, and a light source 32 for transparent originals. Are provided with an irradiation control unit 22a for controlling on / off of the light and an input / output port (not shown). Various signals such as a read command from the I / F 29 and digital image data signals from the image processing unit 28 are input to the main controller 21. Further, from the main controller 21, an irradiation signal to the reflection original light source 31 and the transmission original light source 32, a drive signal to the drive motor 39, a gain adjustment signal to the AFE 27, and a digital image data signal to the I / F 29. Then, a main clock and a read command signal to the CCD controller 25 are output.

  The CCD controller 25 outputs, to the TG 26, a drive signal corresponding to the read start timing of the image sensor 36 generated based on the main clock input from the main controller 21. The TG 26 designates a drive signal to the CCDs 42, 44, 46 of the image sensor 36, an output timing of a shift signal as a command for moving charges from the photodiode to the CCD, and the like, and outputs them to the image sensor 36. The image sensor 36 is configured to move the charge accumulated in the photodiode to the CCD when the shift signal is input from the TG 26, and to output the charge in the CCD to the AFE 27 when the drive signal is input from the TG 26. Has been. The AFE 27 reads the electric charge read from the image sensor 36 as an image analog signal through a correlated double sampler (CDS) processing circuit while suppressing noise, and passes through a variable amplification amplifier that amplifies the signal to an appropriate signal level. It converts to a digital signal of a degree. The image processing unit 28 performs processing such as white balance processing and gamma correction processing on the digital signal input from the AFE 27 to generate image data.

  Next, the operation of the scanner apparatus 10 of the present embodiment configured as described above, particularly the operation of reading the read original M, which is a negative transparent original placed on the reading surface 12, will be described. FIG. 2 is a flowchart illustrating an example of a negative scan processing routine executed by the CPU 22 of the main controller 21. This routine is stored in the ROM 23 and executed after receiving a negative transparent original image reading command from the user PC 50. When this routine is executed, the CPU 22 detects the amount of light emitted from the light source 32 for transmissive originals, and performs an irradiation time T setting process based on the amount of light (step S100). The irradiation time T is a time for irradiating the read original M with light when reading one line of the read original M in the main scanning direction. In the setting process of the irradiation time T, an appropriate range of output values from the CCD (that is, an appropriate range of light amount) is empirically determined based on the image quality of the read image, and the reading document M on the reading surface 12 is determined. The output value from the CCD obtained when the carriage 30 is moved to a position where it is not placed, the rated current is supplied to the transmissive original light source 32, and light is irradiated for a predetermined time so that it falls within this proper range. The process of increasing or decreasing the light irradiation time is performed. When the output value from the obtained CCD is within an appropriate range, the irradiation time is set as the provisional irradiation time of the element array. Subsequently, the same process is performed on the other element rows, and the shortest preliminary irradiation time among the obtained results, that is, the one with the largest amount of light is used as a reference, and a first element row 36R and a second element row 36G which will be described later. The irradiation time T of each element row is determined so as to be a ratio (6: 3: 2) of the charge accumulation interval of the third element row 36B (hereinafter also referred to as “accumulation interval of each element row”). In this way, the irradiation time T of each element array is determined based on the amount of light emitted from the light source 32 for transmissive originals.

  Next, the CPU 22 sets the execution shift interval to the reference processing shift interval (step S110). The shift interval is an interval between a shift signal output to the image sensor 36 at the start of charge accumulation of the image sensor 36 and a shift signal output to the image sensor 36 at the start of reading of the accumulated charge (also referred to as an accumulation interval). The first element row 36R, the second element row 36G, and the third element row 36B are respectively determined. Here, the storage intervals corresponding to the irradiation time T among the plurality of storage intervals stored in advance in the ROM 23 are read and the storage intervals of the respective element arrays are set. The reference processing shift interval is used in a shading setting process described later. The first element row 36R is the longest first accumulation interval, and the second element row 36G is the second longest next to the first element row 36R. The accumulation interval, the third element row 36B is the shortest third accumulation interval, the second accumulation interval is included between the first accumulation intervals, the third accumulation interval is included between the second accumulation intervals, and the first The charges accumulated in the element row 36R, the second element row 36G, and the third element row 36B are read out at the same timing, and the charges of the first element row 36R, the second element row 36G, and the third element row 36B are read. The accumulation interval is set to a ratio of 6: 3: 2 (see FIG. 3 described later). The reason for setting the ratio here is related to reading of a negative transparent original, which will be described in detail later.

  Next, it is determined whether or not the shortest irradiation time T set is less than a predetermined reference time Tref (step S120). This reference time Tref is set empirically at such a time that the image data obtained by reading the read original M with the image sensor 36 has an appropriate image quality. The predetermined time (for example, 80% or 90%) of the storage interval of the element array 36B is set. That is, when the irradiation time T (here, the irradiation time T of the third element row 36B) is not less than the reference time Tref, the light amount of the light source 32 for the transmissive document is appropriate for the accumulation interval of each element row. When the irradiation time T is less than the reference time Tref, the amount of light of the transmissive original light source 32 is large with respect to the accumulation interval of each element row, and the irradiation time of the transmissive original light source 32 is shorter than the accumulation interval. This is the case. As the reading process of the read original M, there is a series of processes of accumulating charges, reading the accumulated charges, and generating an image from the read charges, or any of a plurality of accumulation intervals stored in advance. In some cases, the accumulation interval cannot be set freely, such as by using it. In such a case, the difference between the irradiation time and the accumulation interval becomes large. Here, the relationship between the irradiation time T and the accumulation interval of each element array is determined. When the irradiation time T is not less than the predetermined reference time Tref, that is, when the irradiation time T is within the predetermined reference time Tref, the CPU 22 is set to continuously irradiate the light source 32 for the transmissive document (step S130). , AFE27 gain / offset adjustment processing is executed (step S140). Here, processing for adjusting an appropriate gain to be set in the AFE 27 based on the difference between the output value from the image sensor 36 and the reference value of the AFE 27 is performed.

  Next, the CPU 22 executes a shading setting process (also referred to as a reference process) (step S150). In this reference process, a predetermined white reference and a predetermined black reference are read before the read original M is read (also referred to as a main read process). This is a process for calibrating variations in the amount of light of the light source 32 in the main scanning direction. Specifically, at a position where there is no read original M, the transmissive original light source 32 is turned on and this light is read by the image sensor 36, and the read value is set as a white shading setting value (white reference). Next, it is read by the image sensor 36 with the light source 32 for the transparent document turned off, and the read value is set as the black reference. Here, reading of the white reference in the reference process will be described. FIG. 3 is a timing chart of the reference process during continuous irradiation. As shown in FIG. 3, the CPU 22 performs the following processing based on the shift interval set in step S110. That is, the CPU 22 first drives the drive motor 39 so as to move the carriage 30 to a position where there is no read original M, and controls the light source 32 for the transparent original so as to continuously irradiate (time t1). Next, the CPU 22 controls the CCD controller 25 to output a charge accumulation start shift signal to the first element array 36R (time t2). Then, the first element row 36R starts to accumulate charges. Next, the CCD controller 25 is controlled to output a shift signal to the second element array 36G when the charge accumulation start timing of the second element array 36G is reached (time t3). Then, the second element row 36G starts to accumulate charges. Subsequently, the CCD controller 25 is controlled to output a shift signal to the third element row 36B when the charge accumulation start timing of the third element row 36B is reached (time t4). Then, the third element row 36B starts to accumulate charges. When the read start timing of the accumulated charge is reached, the CPU 22 controls the CCD controller 25 to output the shift signal and the drive signal to all the element rows (time t5). Then, the charge accumulated in each element row is read out from the image sensor 36, and when all the charges are read out, this processing is finished (time t6). The CPU 22 performs A / D conversion on the read charge by the AFE 27 and stores it in the RAM 24 as a white reference. Further, the CPU 22 executes the same processing with the transparent original light source 32 turned off, and stores the result in the RAM 24 as a black reference. In this reference process, one charge accumulation and one charge read are performed.

  Next, the CPU 22 executes a reading process (main reading process) of the read document M (steps S160 to S190). Specifically, the CPU 22 first sets the execution shift interval to the reading processing shift interval (step S160). This read processing shift interval has the same charge accumulation start timing and read start timing of accumulated charge in the first element array 36R, second element array 36G, and third element array 36B, and the first element array 36R. The charge accumulation intervals of 36R, the second element row 36G, and the third element row 36B are set to have a ratio of 1: 1: 1 (see FIG. 4 described later). Here, when the read original M is a negative transparent original including many dark areas with small gradations, the second element row 36G and the third element row 36B that read green and blue, which are difficult to transmit light, It is preferable to increase the output value (charge) relative to the first element row 36R. Here, the reference processing is executed so that the accumulation interval of each element row becomes a ratio of 6: 3: 2 (that is, 1: 1/2: 1/3), and the accumulation interval of each element row is changed to 1: 1: The main reading process is executed so as to have a ratio of 1, and the result of the main reading process is calibrated based on the result of the reference process. The output values of the element array 36G and the third element array 36B are relatively corrected so as to have a ratio of 1: 2: 3.

  Next, the CPU 22 executes a reading process for the read original M (step S170). In this reading process, the image sensor 36 accumulates the light transmitted through the read document M as a charge at the set shift interval while continuously illuminating the light source 32 for the transparent document and moving the carriage 30 in the sub-scanning direction. A process of reading out the generated charges from the image sensor 36 is performed. When the charge is input from the image sensor 36, the CPU 22 causes the AFE 27 and the image processing unit 28 to convert the read charge into image data (step S180). Then, it is determined whether or not the reading process has been completed based on whether or not the entire scanning designated range has been scanned (step S190). If the reading process has not been completed, the processes after step S170 are executed. When the reading process is finished, this routine is finished. The processing in steps S170 to S190 will be described with reference to FIG. FIG. 4 is a timing chart of the main reading process at the time of continuous irradiation. In this reading process, as shown in FIG. 4, the CPU 22 continuously irradiates the light source 32 for transmission originals (time t7), and controls the CCD controller 25 to output shift signals to all the element rows (time t8). . Then, all the element rows start accumulating read image charges at the same timing. Next, when the read start timing is reached, the shift signal and the drive signal are output to all the element rows (time t9). Then, in each element row, the charge accumulated in the photodiode is moved to the CCD, and the charge is read from the CCD. At this time, charge accumulation is newly started, and when the next read start timing is reached, a shift signal and a drive signal are output to all the element rows. By repeating this processing, the read original M is read. As described above, when the irradiation time T is within the reference time Tref, that is, when the light quantity of the light source 32 for the transparent original is within the reference, the light source 32 for the transparent original is continuously irradiated and the accumulation interval is set for each element row. Light is emitted all over, and then the accumulated charge is read out.

  On the other hand, when the shortest irradiation time T is shorter than the predetermined reference time Tref in step S120, that is, when the light amount of the transmissive original light source 32 is large with respect to the accumulation interval of each element row, the CPU 22 A pulse irradiation time TA for shortening the irradiation time of the light source 32 for the transmissive original with respect to the accumulation interval and a pulse number N that is the number of irradiation of light of this pulse irradiation time TA to each element array are set. (Step S200). This pulse irradiation time TA is determined as the same time common to the first element row 36R, the second element row 36G, and the third element row 36B. Further, the number N of pulses determined for each element row is a number that becomes the irradiation time T set for each element row when multiplied by the pulse irradiation time TA, and a value that can maximize the pulse irradiation time TA. It is stipulated in. Specifically, for example, when the accumulation interval of each element row is set to a ratio of 6: 3: 2, the accumulation interval of the first element row 36R is 12 ms, and the accumulation interval of the second element row 36G is 6 ms. When the accumulation interval of the third element array 36B is 4 ms, the irradiation time T of the first element array 36R is 6 ms, the irradiation time of the second element array 36G is 3 ms, and the irradiation time of the third element array 36B is 2 ms, the pulse The irradiation time TA is set to 1 ms, the number of pulses in the first element row 36R is set to 6, the number of pulses in the second element row 36G is set to 3, and the number of pulses in the third element row 36B is set to 2 times. With this setting, the image sensor 36 is irradiated with light for a part of time during the charge accumulation interval (see FIG. 5 described later).

  Subsequently, the CPU 22 executes the same processing as steps S140 to S190 described above except that light is pulsed by the light source 32 for transmissive originals (steps S210 to 260). Here, in order to avoid duplication of description, the reference process (step S220) and the main reading process (steps S240 to S260) which are main points will be described. FIG. 5 is a timing chart of the reference process at the time of pulse irradiation. In the reference process, the CPU 22 executes the following process based on the shift interval set in step S110 as shown in FIG. That is, the CPU 22 first drives the drive motor 39 so as to move the carriage 30 to a position where there is no read original M as white reference reading, and outputs a shift signal for starting charge accumulation to the first element row 36R. The CCD controller 25 is controlled (time t10). Then, the first element row 36R starts to accumulate charges in a state where no light is irradiated. Next, the transmissive original light source 32 is controlled to emit light of the set number of pulses for a pulse irradiation time TA from a predetermined timing (time t11). Here, during the first accumulation interval of the first element row 36R and before reaching the second and third accumulation intervals (time t10 to t12), the first element row 36R is irradiated with three pulses of the pulse irradiation time TA. Next, during the first and second accumulation intervals and before reaching the third accumulation interval (time t12 to t13), one pulse of the pulse irradiation time TA to the first element row 36R and the second element row 36G Irradiation is performed, and then, during the first, second, and third accumulation intervals, two pulse irradiations of the pulse irradiation time TA are performed on all the element rows (time t13 to t14), and the same timing is applied from all the element rows. Then, the CCD controller 25 and the transmissive original light source 32 are controlled so as to read out the accumulated charges (time t14). It should be noted that the pulse irradiation of the light source 32 for transmissive originals is executed so that each pulse is equally spaced. Here, as shown in the circle of FIG. 5, even if light is irradiated for the set pulse irradiation time TA, the charge accumulation shifts at the rise and fall of the light, so the actual irradiation time Ta is the pulse Deviation from the irradiation time TA. Here, during the same pulse irradiation time TA, light is irradiated with a predetermined number of pulses, that is, a predetermined ratio is established by maintaining the ratio of the rise and fall of light in each element row. The ratio of irradiation time is maintained. Then, when all the charges are read, this process is finished (time t15). Similarly to step S150, the CPU 22 also reads out the black reference, and stores the read results in the RAM 24 as the white reference and the black reference.

  Next, the main reading process (steps S240 to S260) will be described with reference to FIG. FIG. 6 is a timing chart of the main reading process at the time of pulse irradiation. In this reading process, as shown in FIG. 6, the CPU 22 controls the CCD controller 25 to output shift signals to all the element rows (time t16). Then, all the element rows start accumulating charges for the read image at the same timing in a state where no light is irradiated. Next, the transmissive original light source 32 is controlled to emit light of the set number of pulses for a pulse irradiation time TA from a predetermined timing (time t17). Here, six pulse irradiations were performed. It should be noted that the pulse irradiation of the light source 32 for transmissive originals is executed so that each pulse is equally spaced. Next, when the read start timing is reached, a shift signal and a drive signal are output to all the element rows (time t18). Then, in each element row, the charge accumulated in the photodiode is moved to the CCD, and the charge is read from the CCD. At this time, charge accumulation is newly started, and when the next read start timing is reached, a shift signal and a drive signal are output to all the element rows. By repeating this processing, the read original M is read. As described above, when the irradiation time T is shorter than the reference time Tref, that is, when the light amount of the light source 32 for the transmissive document is higher than the reference, the light source 32 for the transmissive document is pulsed using the pulse irradiation time TA common to each element row. Then, a part of the accumulation interval is irradiated with light to each element row, and then the accumulated charges are read out.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. In this embodiment, the light source 32 for transmissive document corresponds to the irradiation unit of the present invention, the image sensor 36 corresponds to the image reading unit, among which the photodiode 41 corresponds to the first photoelectric conversion element, and the photodiode 43 corresponds. It corresponds to a second photoelectric conversion element, the photodiode 45 corresponds to a third photoelectric conversion element, the first element row 36R corresponds to a first element row, and the second element row 36G corresponds to a second element row. The third element array 36B corresponds to a third element array, and the control unit 20 corresponds to an accumulation interval setting means, an irradiation time setting means, a pulse setting means, and a control means. Further, the negative transmission original corresponds to a suppression original, the reference time Tref corresponds to a predetermined reference time, and the pulse irradiation time TA corresponds to a unit pulse time. In this embodiment, an example of the image reading method of the present invention is also clarified by describing the operation of the scanner device 10.

  According to the scanner device 10 of the present embodiment described in detail above, when the object to be read is a negative transmission original, the irradiation time T of each element row is set so that the amount of light detected by the image sensor 36 falls within a predetermined appropriate range. Based on the irradiation time T, the reference processing shift interval is set such that the first element row 36R has the longest first accumulation interval, the second element row 36G has the second longest second accumulation interval, and the third element row 36B. Is the shortest third accumulation interval, the second accumulation interval is included in the first accumulation interval, and the third accumulation interval is included in the second accumulation interval, and all the element rows have the same timing. When the accumulated charge is read out and the accumulation interval of each element array is set to a ratio of 6: 3: 2, and the irradiation time T is shorter than the reference time Tref, the ratio of the accumulation intervals and the respective irradiation times And each element based on The pulse irradiation time TA common to both and the number of pulses of each element row is set based on the ratio of the accumulation intervals, and charge accumulation and reading of each element row are performed based on the accumulation interval, and the accumulation interval Meanwhile, light is irradiated to each element row based on the pulse irradiation time TA and the pulse number N. In this way, light is pulse-irradiated to each element array with the number of pulses determined for each element array with a pulse irradiation time TA common to each element array, so that the charge generated by the rise and fall of light irradiation is reduced. Accumulation deviation can be suppressed. Therefore, it is possible to prevent a predetermined ratio of light emitted from each element array from being shifted, and thus it is possible to suppress a decrease in quality of an image as a reading result. It should be noted that it is possible to suppress a change in the color of the read image as compared with a case where the light supplied to the transparent original light source 32 is weakened to reduce the light quantity when the light quantity of the transparent original light source 32 is large. In addition, since charge is accumulated in each element row in an overlapping manner, the time required for the entire reading process can be further shortened. Furthermore, since the timing for reading the accumulated charge is the same for each element row, it is easy to read the accumulated charge. Furthermore, since the pulse irradiation time TA is made the longest, the deviation of the light amount due to the rising and falling of the light irradiation can be most suppressed. Since pulse irradiation is performed at equal intervals during the reference processing and the main reading processing, a reading result with a more uniform image quality can be obtained as compared with the case where pulse irradiation is performed at different intervals. In addition, each element array is calibrated by setting the accumulation interval of each element array to a predetermined ratio during the reference process, and each accumulation interval is made the same in the reading process. The reading process can be made relatively simple, and in this reading process, charges are not read out from other element rows during the storage of any of the element rows. Thus, it is easy to carry out the reading of the electric charges in an overlapping manner, and as a result, the time required for the entire reading process can be further shortened. In addition, since any one of the plurality of shift intervals stored in advance in the ROM 23 is read and the shift interval for execution of each element array is set, the processing is simple.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the above-described embodiment, the charge accumulation intervals of the first element row 36R, the second element row 36G, and the third element row 36B are set to have a ratio of 6: 3: 2 in the reference process, and the main reading is performed. In the processing, the ratio is set to 1: 1: 1. However, as shown in FIG. 7, the charge accumulation intervals of the first element row 36R, the second element row 36G, and the third element row 36B are the reference processing. Then, the ratio may be set to 1: 1: 1, and the ratio may be set to 2: 3: 6 in the reading process. In other words, when performing pulse irradiation, light may be emitted from the light source 32 for the transparent original to the respective element rows via the read original M, or from the light source 32 for the transparent original without passing through the read original M. It is good also as what irradiates light to an element row | line | column. Specifically, in the reference process, processing is performed as the shift interval (time t30, 31) of the first element row 36R in the main reading process, and in the main reading process, the second element row 36G is compared with the first element row 36R. The third element row 36B is set to have a long shift interval. In this way, the ratio of the irradiation time to each element row can be maintained, and the time required for reading the read original M becomes longer, but the second element row 36G and the third element row 36B can sufficiently accumulate charges. Therefore, higher image quality of the read result can be obtained.

  In the above-described embodiment, the reference processing shift interval is such that the first element row 36R has the longest first accumulation interval, the second element row 36G has the second longest accumulation interval, and the third element row 36B has the shortest third accumulation interval. The accumulation interval includes the third accumulation interval between the second accumulation intervals and the second accumulation interval between the first accumulation intervals, and reads out the charges accumulated therein from each element row at the same timing. However, one or more of these may be omitted. For example, the second accumulation interval and the third accumulation interval may be the same, or charge accumulation in each element row may be performed without overlapping or partially overlapping, as shown in FIG. The timing for starting charge accumulation in each element array may be set to the same timing.

  In the above-described embodiment, the storage interval of each element array is set to have a ratio of 6: 3: 2. However, the present invention is not limited to this, and any value may be used as long as at least one is different from the other. . Further, the pulse irradiation time TA is set to be the longest. However, the present invention is not limited to this. For example, in the above embodiment, the pulse irradiation time TA is halved and the number of pulses of the first element row 36R is 6 × 2 = It does not matter if it is 12 times.

  In the embodiment described above, the read original M is a negative transparent original in which the transmission of green and blue light is suppressed. However, the present invention is not limited to this, and transmission of a specific color or reflection of a specific color is suppressed. The pulse control may be performed when the document is used. Alternatively, the above-described pulse control may be performed for a case where the accumulation interval of each element row is set to a predetermined ratio (excluding the ratio of 1: 1: 1) regardless of light transmission or reflection of the read document M. The reference time Tref is set to a predetermined ratio (for example, 80%, 90%, etc.) of the accumulation interval. However, the reference time Tref may be set to a time at which the read image data has an appropriate image quality. There may be. Further, in the pulse irradiation, the light irradiation for the pulse irradiation time TA may be performed over the number of pulses N so as to be equal intervals between the shift intervals, and the light irradiation is not equal intervals during the accumulation intervals. As described above, the light irradiation for the pulse irradiation time TA may be performed over the number of pulses N.

  In the above-described embodiment, the image reading apparatus of the present invention has been described as the scanner apparatus 10, but it may be a multifunction printer provided with a printing apparatus or a FAX apparatus. Further, although the present invention has been described in the form of the scanner device 10, it may be in the form of an image reading method or a program aspect of this method.

1 is a configuration diagram showing an outline of a configuration of a scanner device 10 of the present invention. It is a flowchart showing an example of a negative scan process routine. It is a timing chart of the standard processing at the time of continuous irradiation. It is a timing chart of this reading process at the time of continuous irradiation. It is a timing chart of the standard processing at the time of pulse irradiation. It is a timing chart of the main reading process at the time of pulse irradiation. It is a timing chart of the reference process at the time of another pulse irradiation and this reading process. It is a timing chart at the time of another pulse irradiation.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Scanner apparatus, 12 Reading surface, 20 Control unit, 21 Main controller, 22 CPU, 22a Irradiation control part, 23 ROM, 24 RAM, 25 CCD controller, 26 Timing generator (TG), 27 Analog front end (AFE), 28 Image processing unit, 29 interface (I / F), 30 carriage, 31 light source for reflection original, 32 light source for transmission original, 33 mirror, 34 condenser lens, 36 image sensor, 36R first element row, 36G second element row 36B Third element array, 38 Carriage belt, 38a Driven roller, 39 Drive motor, 41, 43, 45 Photodiode, 42, 44, 46 CCD, 50 User personal computer (PC).

Claims (8)

Irradiating means for irradiating the reading object with white light;
The first element array having a plurality of first photoelectric conversion elements that can detect the amount of light and photoelectrically convert and accumulate charges, and the second element array and the photoelectric elements that have a plurality of second photoelectric conversion elements that photoelectrically convert and accumulate charges. Image reading means comprising one or more third element arrays each having a plurality of third photoelectric conversion elements that convert and store charges;
Based on the light amount of the irradiation means detected by the image reading means, a first irradiation time to the first element row, a second irradiation time to the second element row, and a third to the third element row. An irradiation time setting means for setting the irradiation time;
Based on the set irradiation time, the first accumulation interval, which is an interval from the start of accumulation of charges in the photoelectric conversion elements of the first element array to the reading of the accumulated charges, and the photoelectric conversion of the second element array A second accumulation interval, which is an interval from the start of accumulation of charge in the element to reading out the accumulated charge, and an interval from the start of accumulation of charge in the photoelectric conversion elements of the third element array to the readout of the accumulated charge. Accumulation interval setting means for setting at least one of the certain third accumulation intervals as a different interval and setting the respective accumulation intervals so that the first accumulation interval, the second accumulation interval, and the third accumulation interval have a predetermined ratio. When,
When the set irradiation time is shorter than a predetermined reference time determined based on the storage interval of the element array corresponding to the irradiation time, the predetermined ratio of the storage interval, the first irradiation time, and the second irradiation time Based on the third irradiation time and the third irradiation time, a unit pulse time common to the respective element rows and a pulse number which is the number of irradiation of light of the unit pulse time to each of the element rows are set in the respective element rows. Pulse setting means for
Based on the set accumulation interval, the image reading means is controlled to start accumulating charges in the photoelectric conversion elements of the respective element arrays and read the accumulated charges, and the set value is set during the accumulation interval. Control means for controlling the irradiating means to irradiate light to each of the element rows based on the unit pulse time and the number of pulses,
An image reading apparatus comprising: The accumulation interval setting means sets the first accumulation interval to the longest accumulation interval, sets the second accumulation interval to the accumulation interval next to the first accumulation interval, and sets the third accumulation interval to the shortest. Set the accumulation interval,
The control means controls the irradiating means to irradiate the pulse while including the second accumulation interval between the first accumulation intervals and the third accumulation interval between the second accumulation intervals. The image reading apparatus according to claim 1.   The control means performs pulse irradiation on the first element row during the first accumulation interval, and subsequently pulse irradiation on the first and second element rows during the first and second accumulation intervals. Subsequently, pulse irradiation is performed on the first, second, and third element rows during the first, second, and third accumulation intervals, and the same is applied to the first, second, and third element rows. The image reading apparatus according to claim 2, wherein the irradiation unit and the image reading unit are controlled so as to read the accumulated electric charge at a timing. In the accumulation interval setting means, the first accumulation interval, the second accumulation interval, and the third accumulation interval have a ratio of X: Y: Z (X> Y ≧ Z and X, Y, and Z are positive integers). Set each accumulation interval so that
The pulse setting means sets the number of pulses of the first element row to X × n times (n is an integer of 1 or more), the number of pulses of the second element row is Y × n times, and the number of pulses of the third element row. Is set to Z × n times,
The control means applies (X−Y) × n pulse irradiations of the set unit pulse time to the first element row during the first accumulation interval and before reaching the second and third accumulation intervals. (YZ) × n times of the set unit pulse time to the first and second element arrays during the first and second accumulation intervals and before reaching the third accumulation interval. Next, z × n times of the set unit pulse time are applied to the first, second, and third element arrays during the first, second, and third accumulation intervals. 4. The image reading apparatus according to claim 3, wherein the irradiation unit and the image reading unit are controlled so as to read out the accumulated charges from the first, second, and third element arrays at the same timing. The accumulation interval setting means sets the respective accumulation intervals in a reference process for reading a predetermined white reference for calibration of the image reading means before the reading process for the reading object, and each of the each in the reading process for the reading object. Set the accumulation interval for
The control means controls the image reading means based on the accumulation interval set for the reference processing, and executes the reference processing by controlling the irradiation means to emit the pulse during the accumulation interval. Then, the image reading unit is controlled based on the accumulation interval set for the reading process of the reading target, and the irradiation unit is controlled to irradiate the pulse at equal intervals during the accumulation interval. The image reading apparatus according to claim 1, wherein a reading process of a reading target is executed.   6. The accumulation interval setting means sets each accumulation interval in the reference process to be the predetermined ratio, and sets each accumulation interval in the reading process to be read to be the same interval. The image reading apparatus described in 1.   The accumulation interval setting means is configured to set the first accumulation interval, the second accumulation interval, and the third accumulation based on the set irradiation time when the reading target is a suppressed document in which transmission of a specific color is suppressed. The accumulation interval is set so that at least one of the intervals is a different interval, and the first accumulation interval, the second accumulation interval, and the third accumulation interval have a predetermined ratio. An image reading apparatus according to claim 1. Irradiation means for irradiating the reading target with white light, and a second element that can detect the amount of light and photoelectrically convert and store the charge by photoelectric conversion with a first element array having a plurality of first photoelectric conversion elements that store the charge. An image reading apparatus comprising: a second element array having a plurality of photoelectric conversion elements; and an image reading unit including at least one third element array having a plurality of third photoelectric conversion elements that perform photoelectric conversion and store charges. An image reading method using
(A) Based on the light amount of the irradiation unit detected by the image reading unit, the first irradiation time to the first element row, the second irradiation time to the second element row, and the third element row Respectively setting the third irradiation time of
(B) based on the irradiation time set in the step (a), a first accumulation interval that is an interval from the start of accumulation of charges to the photoelectric conversion elements of the first element array until the accumulated charges are read out; The second accumulation interval, which is an interval from the start of charge accumulation to the photoelectric conversion elements of the second element row to the reading of the accumulated charge, and the accumulation from the start of charge accumulation to the photoelectric conversion elements of the third element row Each accumulation is performed so that at least one of the third accumulation intervals, which is an interval until the read charge is read out, is a different interval, and the first accumulation interval, the second accumulation interval, and the third accumulation interval have a predetermined ratio. A step for setting the interval;
(C) When the irradiation time set in step (a) is shorter than a predetermined reference time determined based on the storage interval of the element array corresponding to the irradiation time, the predetermined ratio of the storage intervals and the first Based on the irradiation time, the second irradiation time, and the third irradiation time, the unit pulse time that is common to each element row and the number of pulses that is the number of irradiation of light of the unit pulse time to each element row Setting each of the element rows;
(D) based on the accumulation interval set in the step (b), controlling the image reading means to start accumulating charges in the photoelectric conversion elements of the respective element arrays and reading the accumulated charges, Controlling the irradiating means to irradiate light to the respective element rows based on the unit pulse time and the pulse number set in the step (c) during the accumulation interval;
An image reading method including:

Images