JP2006270895A - Image-reading apparatus and image-reading method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image-reading apparatus and image reading method, wherein high-definition image information can be efficiently obtained. <P>SOLUTION: First, an amount of light of a light source is detected (step 110 and step 112), and the light source and an image sensor are located at an initial location. In this state, variations in the amount of light of the light source, after the light source and the image sensor have shifted from the initial location to an arrangement location, is derived, based on the detected amount of light and state information (step 114); and it is determined whether the derived amount of light is equal to or smaller than the predetermined change allowance (step 116), whereby control is made to start shifting of an image reading with a timing that it has been determined as being equal to or smaller than the change allowed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention integrally moves a light source and an image sensor from a predetermined initial position to an arrangement position of a reading target image, irradiates the reading target image with light from the light source, and starts from the reading target image. The present invention relates to an image reading apparatus and an image reading method for receiving image information indicating the image to be read by receiving the reflected light.

  2. Description of the Related Art In recent years, image forming apparatuses such as printers and copiers have been developed with higher definition and higher image quality, and it is required to evaluate the image quality of formed images with high accuracy.

  In order to evaluate the image quality with such high accuracy, it is necessary to acquire high-definition image information of the formed image. To acquire high-definition image information, a large number of light receiving elements are required. It is necessary to use an image sensor arranged at a density and to irradiate a reading target image with a large amount of light from a light source, and to receive sufficient reflected light from the image with a large amount of light by each light receiving element.

  However, as shown in FIG. 3 as an example, a light source with a large amount of light (for example, a halogen lamp) starts application of a predetermined voltage that causes the light source to emit light in order to acquire image information (t1 in FIG. 3). Starts increasing, and the increase in the amount of light gradually decreases, and it takes a certain time until the amount of light according to the applied voltage becomes substantially constant.

  On the other hand, in order to acquire high-definition image information, it is necessary to suppress noise due to a change in the light amount of the light source to a predetermined amount or less, so after waiting for the light amount to stabilize after starting applying a predetermined voltage It is necessary to read an image, which is an obstacle to shortening the image reading time.

Therefore, as a technique for shortening the image reading time, Patent Document 1 discloses a technique for shortening a lamp rise time by heating a halogen lamp with a heater. Patent Document 2 discloses a technique for adjusting the amount of reflected light received by a line sensor by predicting a change in the amount of light from the temperature of the halogen lamp and adjusting the moving speed of the line sensor that scans the image. ing. Further, it is conceivable to always turn on the light source with a necessary light amount.
JP 2001-160888 A JP-A-7-107249

  However, the techniques of Patent Document 1 and Patent Document 2 have a problem that high-definition image information may not be acquired efficiently.

  That is, even if the halogen lamp is heated by a heater according to the technique of Patent Document 1, the temperature of heating by the heater is limited, so that the filament temperature of the lamp cannot be increased efficiently, and the light quantity is stabilized. It is not enough to shorten the time until.

  Further, even if it is attempted to detect a change in the light amount by detecting the lamp temperature of the halogen lamp by the technique of Patent Document 2, it is difficult to detect a minute change in the light amount from the lamp temperature, and noise due to the change in the light amount is less than a predetermined amount. It is difficult to keep down.

  Further, when the light source is always turned on with the necessary light amount, as described above, since it is necessary to irradiate a large amount of light from the light source in order to acquire high-definition image information, the image to be read is recorded. If the light from the light source enters the eyes of the operator when the recording medium is changed, there is a risk of causing trouble.

  SUMMARY An advantage of some aspects of the invention is to provide an image reading apparatus and an image reading method capable of efficiently acquiring high-definition image information.

  In order to achieve the above-described object, the invention according to claim 1 is configured to receive a light source that irradiates light to the reading target image, and reflected light of the light irradiated to the reading target image from the light source. An image sensor that acquires image information indicating the image to be read; a moving unit that integrally moves the light source and the image sensor from a predetermined initial position to an arrangement position of the image to be read; and the image sensor Storage means for storing in advance state information indicating a change in the amount of light with time of the light source from the time when a predetermined voltage for emitting the light source is applied to obtain the image information, and the amount of light of the light source. With the detecting means for detecting, and the light source and the image sensor being located at the initial position, the light source and the image sensor are moved from the initial position to the arrangement position by the moving means. Deriving means for deriving the amount of change in the light amount of the light source after being moved based on the light amount detected by the detecting means and the state information; and the amount of change derived by the deriving means Determining means for determining whether or not the capacity has become equal to or less than the capacity; and control means for controlling the moving means to start the movement at a timing determined by the determining means to be equal to or less than the allowable change amount. ing.

  In the image reading apparatus according to claim 1, the moving unit integrally moves the light source and the image sensor from a predetermined initial position to an arrangement position of the reading target image by the moving unit, and the reading target image is moved by the light source. The image sensor receives the reflected light from the image to be read and acquires image information indicating the image to be read, and acquires the image information by the image sensor in a storage unit. In order to do so, state information indicating the state of change in the amount of light of the light source over time since the time when a predetermined voltage for causing the light source to emit light is applied is stored in advance. The storage means includes a semiconductor memory such as a RAM, a ROM, and a flash memory, a portable memory such as a compact flash (registered trademark) and an xD picture card (registered trademark), and a fixed storage device such as a hard disk. The image sensor includes a line sensor and an area sensor. In the case of a line sensor, the image to be read and the line sensor are relatively moved, and reflected light or transmitted light is received by the line sensor to acquire image information.

  In the image reading apparatus of the present invention, the light amount of the light source is detected by the detecting unit, and the light source and the image sensor are in the state where the light source and the image sensor are positioned at the initial position by the deriving unit. A change amount of the light amount of the light source after being moved by the moving unit from the initial position to the arrangement position is derived based on the light amount detected by the detecting unit and the state information, and by a determining unit, It is determined whether or not the amount of change derived by the deriving means is less than or equal to a predetermined change allowable amount, and the movement is started when the control means determines that the change amount is less than or equal to the allowable change amount. Thus, the moving means is controlled.

  Thus, according to the first aspect of the present invention, the light source and the image sensor are arranged from the initial position in the state where the light amount of the light source is detected and the light source and the image sensor are located at the initial position. The amount of change in the light amount of the light source after being moved to the installation position is derived based on the detected light amount and the state information, and it is determined whether or not the derived change amount is equal to or less than a predetermined change allowable amount, Since the control for starting the movement for acquiring the image information of the image to be read is started at the timing when it is determined that the change is less than or equal to the allowable change amount, high-definition image information can be acquired efficiently.

  The present invention is indicated by input means for inputting accuracy information indicating the reading accuracy of the image to be read by the image sensor, and accuracy information input by the input means, as in the invention of claim 2. Setting means for setting the change allowable amount to be smaller as the reading accuracy is higher may be further provided. Note that the input by the input means includes input from an external device via a communication line such as a LAN, the Internet, and an intranet, in addition to input via an input device such as a keyboard and a pointing device.

  According to a third aspect of the present invention, a white reference plate for shading correction is provided at the initial position, and the light irradiated from the light source is reflected from the white reference plate on the detection unit. A change rate calculating means for calculating a change rate of the amount of light received by the image sensor a plurality of times, and a specifying means for specifying the amount of light that becomes the change rate as the light amount of the light source based on the state information. It may be a thing.

  According to a third aspect of the present invention, as in the fourth aspect of the present invention, the reflected light from the white reference plate is reflected by the image sensor at the timing when the determination means determines that the change is less than the allowable amount. Generation means for generating correction data for performing shading correction based on image information acquired by receiving light, and shading based on the correction data for image information indicating the image to be read acquired by the image sensor It may be further provided with correction means for performing correction.

  Further, according to the present invention, as in the fifth aspect of the present invention, when the determination unit does not determine that the change amount is equal to or less than the change allowable amount within a predetermined period, the replacement of the light source is performed. Presentation means for presenting information that prompts the user may be further provided. The presentation (output) means includes presentation (display) by a display device such as a CRT display, plasma display, organic EL display, and liquid crystal display, and presentation (output) by printing by a printer, as well as LAN, Internet, and intranet. Presentation (output) to an external device via the network.

  Further, according to the present invention, as in the sixth aspect of the present invention, when the control means does not determine that the change amount has become equal to or less than the allowable change amount by the determination means within a predetermined period. The power supply to the light source may be controlled so that the change amount is equal to or less than the change allowable amount.

  According to a seventh aspect of the present invention, as in the seventh aspect of the present invention, the control unit is turned on with a predetermined light amount that is smaller than that at the time of acquisition of image information while the light source is not performing acquisition of the image information. As such, the power supply to the light source may be controlled.

  On the other hand, in order to achieve the above-mentioned object, the invention according to claim 8, the light source and the image sensor are integrally moved from a predetermined initial position to the arrangement position of the reading target image, and the reading target image is moved from the light source. An image reading method for obtaining image information indicating the read target image by irradiating light to the light, receiving reflected light from the read target image, and acquiring the image information by the image sensor When state information indicating a state of change in light quantity of the light source over time from the time when a predetermined voltage for causing the light source to emit light is stored in the storage unit in advance, the light source and the image sensor are at the initial position. Based on the light amount of the light source and the state information, the amount of change in the light amount of the light source after the light source and the image sensor are moved from the initial position to the arrangement position in the positioned state. And determining whether or not the derived change amount is equal to or less than a predetermined allowable change amount, and at the timing when it is determined that the change amount is equal to or less than the allowable change amount, the image to be read is read from the initial position of the light source and the image sensor. Control is performed so as to start the movement to the arrangement position.

  Therefore, since the invention described in claim 8 operates in the same manner as the invention described in claim 1, high-definition image information can be acquired efficiently as in the invention described in claim 1.

  As described above, according to the present invention, the light amount of the light source is detected, and the light source and the image sensor are moved from the initial position to the arrangement position in a state where the light source and the image sensor are positioned at the initial position. The amount of change in the light amount of the light source after being derived is derived based on the detected light amount and state information, and it is determined whether or not the derived change amount is less than or equal to a predetermined change allowable amount, and the change allowable amount or less. Since it is controlled to start the movement for acquiring the image information of the image to be read at the timing determined to have become, it has an excellent effect that high-definition image information can be acquired efficiently. Have.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, a case where the present invention is applied to an image evaluation apparatus that reads an image and evaluates the image quality of the image will be described.

  FIG. 1 shows a schematic configuration of an image evaluation apparatus 10 according to the present embodiment.

  As shown in the figure, the image evaluation apparatus 10 is provided with a white reference plate 16 at one end, a stage 14 on which a recording sheet 12 on which an image to be read is recorded, and a stage 14. An image reading unit 20 that reads an image of the recording paper 12 placed thereon.

  Note that the position corresponding to the position where the white reference plate 16 is disposed on the stage 14 is an initial position (home position) when the image reading unit 20 reads an image. Between the other end of the stage 14, the motor 54 (omitted in FIG. 1, see FIG. 2) can be moved in parallel to the surface of the stage 14 at a predetermined speed.

  The image reading unit 20 according to the present embodiment includes a pair of illumination devices 22 arranged in parallel to the surface of the stage 14 along a crossing direction that intersects the moving direction of the image reading unit 20, and the pair of lighting devices 22. A CCD (Charge Coupled Devices) line sensor 24 disposed along the intersecting direction between the illuminating devices 22 and a stage 14 side of the CCD line sensor 24. And a lens 26 that forms an image of the reflected light on the CCD line sensor.

  In the present embodiment, a halogen lamp is used as the illumination device 22, but the present invention is not limited to this, and another illumination light source such as a fluorescent lamp or a rare gas lamp may be used.

  FIG. 2 shows the configuration of the electrical system of the image evaluation apparatus 10 according to the present embodiment.

  As shown in the figure, the image evaluation apparatus 10 includes a CPU (central processing unit) 40 that controls the entire operation, various programs including various control programs for controlling the entire apparatus, an image evaluation processing program described later, various parameters, and the like. Is stored in advance, a RAM 44 that temporarily stores various data, a display 46 that displays various information, a display driver 48 that controls display of various information on the display 46, and an input device 50 such as a keyboard. And.

  Further, the image evaluation apparatus 10 moves a hard disk drive (hereinafter referred to as “HDD”) 52 in which light amount change information (corresponding to “status information” of the present invention) described later is stored in advance and the image reading unit 20. A drive control unit 56 that controls a drive signal to the motor 54, an illumination control unit 58 that controls the supply of power to the illumination device 22, and a sensor control unit 60 that controls the reading of image information by the CCD line sensor 24. It is equipped with.

  The CPU 40, ROM 42, RAM 44, display driver 48, input device 50, HDD 52, drive control unit 56, illumination control unit 58, and sensor control unit 60 are connected to each other via a system bus BUS. Therefore, the CPU 40 accesses the ROM 42, RAM 44, and HDD 52, displays various information on the display 46 via the display driver 48, grasps the operation contents by the operator for the input device 50, and drives the drive controller 56. The movement of the image reading unit 20 by controlling the driving of the motor 54, the control of the amount of light emitted from the illumination device 22 through the illumination control unit 58, and the image by the CCD line sensor 24 through the sensor control unit 60. Can be controlled separately.

  By the way, when the image evaluation apparatus 10 according to the present embodiment reads an image, the image evaluation apparatus 10 applies a predetermined reading voltage to the illuminating apparatus 22 so that the illuminating apparatus 22 has a predetermined reading light amount (in the present embodiment, 100,000). In a standby state in which an image is not read, a predetermined standby voltage is applied to the illuminating device 22 so that the illuminating device 22 has a predetermined standby light amount (mainly less than the predetermined read light amount). In the embodiment, the light is lit at 2,000 lux. The predetermined waiting light amount is a light amount that does not cause a failure such as a decrease in blue vision sensitivity, retinal burn, infrared cataract, corneal burn, etc. even if the light irradiated from the illumination device 22 is received by human eyes. It is said.

  Further, in the HDD 52 according to the present embodiment, a relational expression indicating a state of change in light quantity with time of the illumination device 22 after starting to apply a predetermined reading voltage to the illumination device 22 when an image is read is previously stored. It is remembered.

  FIG. 3 shows an example of a change over time in the amount of light when a reading voltage is applied to the illumination device 22.

  As shown in the figure, when a predetermined reading voltage is applied to the illumination device 22 according to the present embodiment, the amount of light to be irradiated increases with time, and a certain amount of time is required until the amount of light stabilizes at the predetermined reading light amount. I need.

  Next, the operation of the image evaluation apparatus 10 according to the present embodiment will be described.

  First, the operation flow of the image evaluation apparatus 10 when evaluating the image quality of an image recorded on the recording paper 12 will be briefly described.

  When the power supply of the image evaluation apparatus 10 is turned on, the lighting device 22 is applied with a predetermined standby voltage and starts lighting with a predetermined standby light amount.

  A recording paper 12 on which an image to be evaluated is recorded by the operator is placed on the stage 14 and an area to be read from the image recorded on the recording paper 12 via the input device 50 (hereinafter referred to as “reading target area”). When the reading conditions such as the size, position, and reading accuracy are input and a predetermined process start operation is performed, the image evaluation apparatus 10 executes an image evaluation process to be described later, Start reading the target area.

  Next, the operation of the image evaluation apparatus 10 when executing the above-described image evaluation process will be described with reference to FIG. FIG. 4 is a flowchart showing the processing flow of the image evaluation processing program executed by the CPU 40 at this time, and the program is stored in a predetermined area of the ROM 42 in advance.

  First, in step 100, the voltage applied to the illumination device 22 is switched, and the application of the reading voltage to the illumination device 22 is started.

  In the next step 102, based on the size and position of the reading target area input by the operator via the input device 50, the image reading unit 20 is moved from the initial position to the input position (starting position of the reading target area). The moving time required for moving and the reading time required for reading the image of the reading target area are calculated.

  For example, as shown in FIG. 5, when the reading target area is the area 70A of the recording paper 12, the area 70A is located near the white reference plate 16, so that the movement time required for movement is short. Since the size of the area 70A is also small, the reading time required for reading the image of the area 70A is shortened. On the other hand, when the reading target area is the area 70B of the recording paper 12, since the area 70B is located far from the white reference plate 16, the movement time required for movement is long, and the size of the area 70B is also large. For this reason, the reading time required for reading the image in the region 70B becomes long.

  In the next step 104, a permissible change amount indicating a permissible change range of the light amount when reading the read target area is set based on the read accuracy input as the read condition. That is, since the image can be evaluated with higher accuracy when the change in the amount of light when reading the reading target region is smaller, the allowable change amount is set so as to decrease as the input reading accuracy value increases.

  In the next step 106, the image reading unit 20 is moved and the reflected light from the white reference plate 16 is received by the CCD line sensor 24 to detect the amount of light. In the next step 108, the reflection from the previous white reference plate 16 is detected. After a predetermined time (for example, 0.2 seconds) after the light detection, the reflected light from the white reference plate 16 is received by the CCD line sensor 24 and the amount of light is detected again. The change rate of the light amount is calculated from the difference between the two light amounts.

  In the next step 112, based on the relational expression showing the change over time of the light amount irradiated from the illumination device 22 stored in the HDD 52, the light amount at which the change rate of the light amount becomes the change rate of the light amount calculated in step 110 is calculated. Identify. That is, the relational expression indicating the change in light quantity with time is an expression showing the relation between time and light quantity. Therefore, by differentiating the relational expression with respect to time, the differentiated relational expression can be expressed as the rate of change between time and light quantity. This is an expression showing the relationship. Therefore, using the differentiated relational expression, the time that is the rate of change of the light quantity calculated in step 110 is obtained, and by substituting the obtained time into the relational expression that is not differentiated, the light quantity change rate calculated in step 110 Specify the amount of light to be.

  In the next step 114, based on the relational expression showing the temporal change in the light quantity specified in step 112 and the light quantity stored in the HDD 52, the light quantity during the reading time after the movement time of the specified light quantity has elapsed. The amount of change is derived.

  For example, as shown in FIG. 3, when the light quantity specified in step 112 is A, and the reading target area is the area 70A shown in FIG. 5, the movement time t2 is short, so the area 70A is changed after the movement time t2. In the case of reading, the illumination device 22 is still standing up, but since the reading time t3 is short, the amount of change in light quantity at the reading time t3 is s1.

  Further, if the reading target area is the area 70B shown in FIG. 5, the movement time t4 is long, so when the area 70B is read after the movement time t4, the light amount of the illumination device 22 is relatively stable. Since the reading time t5 is long, the light amount change at the reading time t5 is s2.

  In the next step 116, it is determined whether or not the change amount of the light amount derived in step 114 is equal to or less than the allowable change amount set in step 104. If the determination is affirmative, the process proceeds to step 118, and a negative determination is made. If it is, the process returns to step 108, and the reflected light from the white reference plate 16 is received again to detect the light quantity. In the next step 110 when a negative determination is made, the change rate of the light amount is calculated from the difference in the light amount of the reflected light of the white reference plate 16 twice immediately before. Note that the processing in step 116 corresponds to the determination means of the present invention.

  In the next step 118, the motor 54 is driven to move the image reading unit 20 with respect to the white reference plate 16, and the CCD line sensor 24 receives the reflected light from the white reference plate 16 to detect the amount of light again. That is, detection is performed again by moving the detection position of the white reference plate 16 so that erroneous detection does not occur due to contamination of the white reference plate 16 or the like.

  In the next step 120, shading for calculating the average value of the amount of light received by each light receiving element of the CCD line sensor 24 detected in the above step 108 and step 118 to correct the sensitivity variation of each light receiving element of the CCD line sensor 24, etc. Create shading correction data for correction.

  In the next step 122, the motor 54 is driven to move the image reading unit 20 at a predetermined speed with respect to the stage 14, and the reflected light from the recording paper 12 placed on the stage 14 is received by the CCD line sensor 24. The image information indicating the image of the reading target area is acquired.

  In the next step 124, the voltage applied to the illumination device 22 is switched from the read voltage to the standby voltage, and the light amount is reduced to a predetermined standby light amount. Thereby, even if the operator replaces the recording paper 12 after completing the imaging, it is possible to prevent the eyes from being damaged by the light from the illumination device 22.

  In the next step 126, the image indicated by the image information is corrected in accordance with the correction data created in step 120.

  In the next step 128, in order to evaluate the image quality based on the corrected image information, various processes are performed to calculate evaluation values such as sharpness, graininess, and gradation. In addition, about this evaluation process, since various general evaluation methods can be applied, detailed process is abbreviate | omitted.

  In the next step 130, the calculated evaluation result is displayed on the display 46, and the image evaluation process is terminated.

  As described above, the image evaluation apparatus 10 according to the present embodiment derives the change amount of the light amount when reading the image of the read target area based on the size and position of the read target area, and the derived change amount is Since the movement of the image reading unit 20 is started at a timing within the allowable change amount, the reading target area can be read even when the lighting device 22 is started up, and the image can be read efficiently. Become. In addition, when evaluating an image with high accuracy, noise due to a change in the amount of light can be adjusted by reducing the allowable change amount, so that precise image information can also be acquired.

  As described above, according to the present embodiment, the image evaluation apparatus 10 uses the moving unit (here, the motor 54) to arrange the reading target image (the image of the reading target region) from the predetermined initial position. The light source (here, the illumination device 22) and the image sensor (here, the CCD line sensor 24) are integrally moved to irradiate the reading target image with light from the light source, and the reading target is read by the image sensor. Image information indicating the image to be read is received by receiving reflected light from the image, and the storage unit (here, HDD 52) causes the light source to emit light in order to acquire the image information by the image sensor. State information indicating the state of change in the amount of light with time of the light source from the time when a predetermined voltage is applied is stored in advance.

  In the present invention, the light quantity of the light source is detected by a detection means (here, step 110 and step 112 of image evaluation processing are equivalent), and by a derivation means (here, step 114 of image evaluation processing is equivalent). The amount of change in the light amount of the light source after the light source and the image sensor are moved from the initial position to the arrangement position by the moving means in a state where the light source and the image sensor are located at the initial position. Is derived based on the light quantity detected by the detection means and the state information, and the amount of change derived by the derivation means is determined by a determination means (here, the step 116 of the image evaluation process is equivalent). It is determined whether or not the change allowable amount has been reached, and the control means (here, the CPU 40) causes the determination means to make the change allowable amount or less. Since controls the moving means so as to start the movement in the determined timing and became, it is possible to obtain a high-definition image information efficiently.

  In addition, according to the present embodiment, the input unit (here, the input device 50) for inputting accuracy information indicating the reading accuracy of the image to be read by the image sensor, and the accuracy information input by the input unit are used. As the reading accuracy shown is higher, it further comprises setting means (in this case, corresponding to step 104 of the image evaluation process) for setting the permissible change amount to be smaller, so that the accuracy of the read image can be adjusted, with an appropriate accuracy. An image can be read efficiently.

  Further, according to the present embodiment, a white reference plate for shading correction is provided at the initial position, and reflected light from the white reference plate of light emitted from the light source is applied to the detection means by the image sensor. Change rate calculation means for calculating the change rate of the amount of light received a plurality of times (here, corresponding to step 110 of the image evaluation process), and the amount of light that becomes the change rate based on the state information is specified as the light amount of the light source Therefore, the light quantity of the light source can be specified without providing a separate sensor for directly detecting the light quantity of the light source. In addition, the amount of light reflected by the white reference plate is attenuated more than the amount of light emitted from the light source due to reflection, so the influence of attenuation due to reflection is reduced by specifying the light amount of the light source from the rate of change of the light amount. Thus, the amount of light emitted from the light source can be appropriately specified.

  Further, according to the present embodiment, based on the image information acquired by receiving the reflected light from the white reference plate by the image sensor at the timing when the determination unit determines that the change is less than the allowable amount. Generating means for generating correction data for performing shading correction (here, corresponding to step 120 of the image evaluation process), and the correction data for the image information indicating the image to be read acquired by the image sensor And a correction means for performing shading correction based on (here, corresponding to the step 126 of the image evaluation process) is further provided, so that unevenness occurring in the read image can be corrected.

  Further, according to the present embodiment, the controller is configured to turn on the light source so that the light source is turned on with a predetermined light amount smaller than that at the time of acquisition of the image information while the light source is not acquired. Therefore, the period of time required for the rise of the amount of light when acquiring image information is shortened, and image reading can be started quickly.

  If the determination in step 116 of the image evaluation process is not affirmative within a predetermined period (for example, 1 minute) after the image evaluation process is started, the light source deteriorates and the amount of light rises gradually. Since it is considered that the period until the light intensity stabilizes is longer, the display 46 displays information prompting the user to replace the light source (for example, the message “The lamp of the lighting device has deteriorated. Replace it”). It is good also as what to do. Thereby, since the lamp of the light source is replaced by the user, it is possible to prevent the image evaluation processing time from being prolonged due to deterioration of the light source. In addition, when the determination in step 116 of the image evaluation process is not affirmative within a predetermined period after the image evaluation process is started, the voltage applied to the light source may be controlled to increase. As a result, the amount of light emitted from the light source rises quickly and stabilizes quickly, so that the amount of change in the amount of light becomes equal to or less than a predetermined change allowable amount, and the image information acquisition timing can be advanced.

  In this embodiment, the case where the amount of light emitted from the light source is specified based on the change rate of the amount of light has been described. However, a sensor that detects the amount of light emitted from the light source is provided and detected by the sensor. The timing at which the change amount of the light amount reading time is equal to or less than the predetermined change allowable amount may be determined from the relational expression stored in the HDD 52 based on the light amount thus obtained. Also in this case, the same effects as in the present embodiment can be obtained.

  In addition, the configuration of the image evaluation apparatus 10 described in this embodiment (see FIGS. 1, 2, and 5) is merely an example, and it is needless to say that the configuration can be changed as appropriate without departing from the gist of the present invention. Yes.

  Further, the flow of image evaluation processing (see FIG. 4) described in the present embodiment is also an example, and it is needless to say that the image evaluation processing can be changed as appropriate without departing from the gist of the present invention.

It is a schematic perspective view which shows the structure of the image evaluation apparatus which concerns on this Embodiment. It is a block diagram which shows the electrical principal part structure of the image evaluation apparatus which concerns on this Embodiment. It is a graph which shows the change of the light quantity irradiated with time of the illuminating device concerning this embodiment. It is a flowchart which shows the flow of a process of the image evaluation processing program which concerns on this Embodiment. FIG. 6 is a schematic perspective view illustrating an example of a region to be read of an image recorded on a recording sheet according to the present embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image evaluation apparatus 12 Recording paper 14 Stage 16 White reference board 22 Illumination device 24 Line sensor 40 CPU
46 Display 52 HDD

Claims (8)

A light source that emits light to an image to be read;
An image sensor that receives reflected light of light emitted from the light source to the reading target image and acquires image information indicating the reading target image;
Moving means for integrally moving the light source and the image sensor from a predetermined initial position to an arrangement position of the reading target image;
Storage means for preliminarily storing state information indicating a state of change in light quantity of the light source over time from the time when a predetermined voltage for emitting the light source is applied to acquire the image information by the image sensor;
Detecting means for detecting the light quantity of the light source;
The amount of change in the light amount of the light source after the light source and the image sensor are moved from the initial position to the arrangement position by the moving means in a state where the light source and the image sensor are located at the initial position. Derivation means for deriving based on the light quantity detected by the detection means and the state information;
Determination means for determining whether or not the amount of change derived by the derivation means is equal to or less than a predetermined allowable change amount;
Control means for controlling the moving means to start the movement at a timing determined by the determining means to be equal to or less than the allowable change amount;
An image reading apparatus comprising: Input means for inputting accuracy information indicating the reading accuracy of the image to be read by the image sensor;
Setting means for setting the change allowable amount to be smaller as the reading accuracy indicated by the accuracy information input by the input unit is higher.
The image reading apparatus according to claim 1, further comprising: A white reference plate for shading correction is provided at the initial position,
In the detection means,
A rate-of-change calculating means for calculating a rate of change of the amount of light received by the image sensor a plurality of times from the white reference plate of the light emitted from the light source;
A specifying means for specifying a light amount that becomes the change rate based on the state information as a light amount of the light source;
The image reading apparatus according to claim 1, comprising: Correction data for performing shading correction based on image information obtained by receiving reflected light from the white reference plate by the image sensor at a timing when the determination unit determines that the change is less than or equal to the allowable amount. Generating means for generating;
Correction means for performing shading correction based on the correction data with respect to image information indicating the read target image acquired by the image sensor;
The image reading apparatus according to claim 3, further comprising: The present invention further comprises a presenting means for presenting information for prompting replacement of the light source when the determining means does not determine that the change amount has become equal to or less than the allowable change amount within a predetermined period. The image reading apparatus according to claim 4. If the control means does not determine that the amount of change is less than or equal to the change allowable amount within a predetermined period, the light source so that the amount of change is less than or equal to the change allowable amount. The image reading apparatus according to claim 1, wherein power supply to the printer is controlled. The control unit controls power supply to the light source so that the light source is turned on with a predetermined light amount smaller than that at the time of acquisition of the image information during standby when the image information is not acquired. The image reading apparatus according to any one of claims 1 to 6. The light source and the image sensor are integrally moved from a predetermined initial position to the arrangement position of the reading target image, light is irradiated from the light source to the reading target image, and reflected light from the reading target image is emitted. An image reading method for receiving light and acquiring image information indicating the image to be read,
State information indicating a state of change in light quantity of the light source over time from the time when a predetermined voltage for emitting the light source is applied in order to acquire the image information by the image sensor is stored in the storage unit in advance. ,
With the light source and the image sensor positioned at the initial position, the amount of change in the light amount of the light source after the light source and the image sensor are moved from the initial position to the arrangement position is expressed as the light amount of the light source. And deriving based on the state information,
It is determined whether or not the derived change amount is equal to or less than a predetermined change allowable amount,
Control to start the movement of the light source and the image sensor from the initial position to the arrangement position of the read target image at a timing determined to be equal to or less than the allowable change amount;
Image reading method.

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