JP2008009128A - Image reader and image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image reader and an image processor, in which light quantity of a light source emitting reading light with which an original is irradiated and output from a photoelectric conversion means, are stabilized appropriately and quickly. <P>SOLUTION: In the color image reader, a lamp 4 starts lighting with maximum light quantity when it starts the lighting, thereafter, a measured value obtained by the digital conversion of output from a CCD 9a by an A/D converter 42b is compared with a target value by an image data comparison part 71; the CLK idle period of a clock signal CLK in one line is obtained by a CLK idle period arithmetic operation part 72 based on the result of comparison; and the clock signal CLK in the CLK idle period is input in an inverter circuit 62, whereby the inverter circuit 62 lights the lamp 4 according to the clock signal CLK in the CLK idle period, to thereby quickly make the light quantity of the lamp 4 stabilized. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image reading apparatus and an image processing apparatus, and more specifically, the output of a photoelectric conversion element that stabilizes the light quantity of a light source that irradiates light on a document inexpensively and promptly, and photoelectrically converts reflected light from the document. The present invention relates to an image reading apparatus and an image processing apparatus that can stabilize image quality quickly and quickly.

  Image readers such as scanners, copiers, and facsimile machines use fluorescent lamps, Xe (xenon) tubes, LEDs (Light Emitting Diodes), or the like as light sources. The image reading device irradiates the original with light from the light source, enters the reflected light from the original into a photoelectric conversion element such as a CCD (Charge Coupled Device), and converts the light into an electrical signal by the photoelectric conversion element. Reading.

  Therefore, in the image reading apparatus, it is important for the image of the document to be read in a good state that the light amount of the light source is appropriate.

  Conventionally, the image reading apparatus has produced a light source with a specific illuminance for each apparatus for various reading speeds and required light amounts for the light receiving elements, so that the reading speeds differ depending on the reading mode (monochrome / color). In order to prevent saturation of the photoelectric conversion element, an optical design adapted to a slow (generally, color) reading mode has been performed.

  As a result, in a system having a high reading speed, there is a possibility that the required light amount is insufficient and the S / N is deteriorated.

  In addition, the same light source cannot be used in image reading apparatuses having different required light amounts, and there is a problem that the number of parts increases, the number of parts increases, and part management becomes difficult.

  Furthermore, when using the same light source with image reading devices with different required light amounts, there are those that use a mechanical shading plate to cut the light amount, but in this case, excessive light is cut off from the photoelectric conversion element. Therefore, there has been a problem that wasteful energy is consumed.

  Also, if a light source adjusted to a high light level based on the temperature characteristics of the light source is lit with a low light level, the light level will gradually increase with respect to the required light level, and the light level will not stabilize until the light source temperature becomes constant. There is a problem that density unevenness occurs every time and the read image deteriorates.

  Conventionally, a flyback inverter circuit in which an external electrode type rare gas fluorescent lamp arranged in the original illumination unit is arranged outside the original illumination unit has a constant energy per pulse generated on the primary side of the transformer. In addition, an external electrode type rare gas fluorescent lamp lighting device has been proposed (see Patent Document 1).

  Conventionally, an image reading apparatus that controls the amount of light based on the reading cycle of each line and the cycle of turning on / off the exposure lamp has been proposed (see Patent Document 2).

Japanese Patent No. 3503542 Japanese Unexamined Patent Publication No. 7-74890

  However, in the above prior art, there is a need for improvement in order to stabilize the light quantity of the light source and the output of the photoelectric conversion element at a lower cost and promptly and to improve the image quality of the read image.

  That is, in the prior art described in Patent Document 1, the energy for each pulse is controlled to be constant and the light is adjusted by changing the frequency of the pulse, but the reference for changing the frequency of the pulse is not clear. In order to stabilize the light quantity of the light source appropriately and promptly, there was a need for improvement.

  In the prior art described in Patent Document 2, the light amount is controlled based on the reading cycle of each line and the lighting lamp on / off cycle, but it is not clear how the light amount control is performed. In order to stabilize the light quantity appropriately and promptly, there was a need for improvement.

  Therefore, the present invention stabilizes the light amount of the light source or the output of the photoelectric conversion means to the target light amount or the target value quickly and inexpensively even when the required target light amount is different, and has good versatility and usability. An object of the present invention is to provide an image reading apparatus and an image processing apparatus capable of improving the image quality of a read image.

  The image reading apparatus according to the first aspect of the present invention outputs a lighting pulse having a predetermined lighting pulse pause period in one line of image reading from the control means to the driving means, and the driving means uses the lighting pulse as a light source. In the image reading apparatus that illuminates the document with the reading light and converts the reflected light from the document into image data by the photoelectric conversion unit, the control unit sets the lighting pulse pause period to be output to the driving unit. The object is achieved by changing and adjusting the light quantity of the light source.

  In this case, for example, as described in claim 2, when the lighting starts at the maximum light amount of the light source, the control unit sets the lighting pulse at the maximum light amount set in advance as the lighting pulse pause period. A lighting pulse pause period longer than the pause period may be output to the driving means.

  For example, as described in claim 3, the control unit may determine the lighting pulse pause period based on image data output from the photoelectric conversion unit and output the period to the driving unit.

  Further, for example, as described in claim 4, the control unit determines the lighting pulse pause period in which the image data output from the photoelectric conversion unit becomes a predetermined target value, and outputs the determined period to the driving unit. Also good.

  For example, as described in claim 5, the control means may gradually change the lighting pulse pause period over a plurality of stages.

  In the image reading apparatus according to the sixth aspect of the invention, the reflected light of the light emitted from the light source to the document is converted into analog image data by the photoelectric conversion means, and the analog image data is subjected to signal processing by the signal processing means and finally processed. In the image reading apparatus for converting into digital image data, the signal processing means performs signal processing on the image data output from the photoelectric conversion means to a predetermined target value at least when the light source is turned on. The goal has been achieved.

  In the case of claim 6, for example, as described in claim 7, the signal processing means amplifies the analog image data from the photoelectric conversion means based on an analog gain value input from the control means. Processing means may be provided, and the control means may output the analog gain value for amplifying the image data output from the photoelectric conversion means to the predetermined target value to the analog signal processing means.

  Further, for example, as described in claim 8, the signal processing unit converts the analog image data from the photoelectric conversion unit into digital image data based on a reference voltage input from the control unit. The control means may output the reference voltage at which the digital image data converted by the digital conversion means becomes a predetermined target value to the digital conversion means.

  Further, for example, as described in claim 9, the signal processing unit is configured to convert the digital image data after digital conversion of the analog image data from the photoelectric conversion unit based on a digital gain value input from the control unit. Digital signal processing means for amplifying the digital image data, the control means for amplifying the digital image data obtained by digitally converting analog image data from the photoelectric conversion means to the predetermined target value, the digital signal processing means May be output.

  In the case of the above first to ninth aspects, for example, as described in the tenth aspect, the image reading apparatus performs the change of the lighting pulse pause period or the signal processing in the signal processing unit for one line of the image reading. It may be performed outside the effective image area.

  An image processing apparatus according to an eleventh aspect of the present invention includes an image reading unit that reads an image of an original by irradiating the original with light from a light source, and various types of image data of the original read by the image reading unit. An image processing apparatus that performs image processing includes the image reading unit according to any one of claims 1 to 10 as the image reading unit, thereby achieving the above object.

  According to the image reading apparatus of the first aspect of the present invention, the lighting pulse pause period in one line of image reading is appropriately changed to adjust the light amount of the light source. The amount of light can be appropriately stabilized to the target amount of light quickly and with a simple configuration, and the image quality of the read image can be improved while improving versatility and usability.

  According to the image reading apparatus of the invention described in claim 6, the signal processing means for performing the signal processing on the analog image data obtained by photoelectrically converting the incident light from the original by the photoelectric conversion means, and finally converting it into digital image data, At least when the light source is turned on, the image data output from the photoelectric conversion means is signal-processed to a predetermined target value, so even if the required target output is different, the output of the photoelectric conversion means can be quickly and easily configured. Thus, the target output can be appropriately stabilized, and the image quality of the read image can be improved while improving versatility and usability.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, since the Example described below is a suitable Example of this invention, various technically preferable restrictions are attached | subjected, However, The scope of the present invention limits this invention especially in the following description. As long as there is no description of the effect, it is not restricted to these aspects.

  1 to 12 are diagrams showing a first embodiment of an image reading apparatus and an image processing apparatus according to the present invention, and FIG. 1 is an application of the first embodiment of the image reading apparatus and the image processing apparatus according to the present invention. 1 is a schematic front view of a color image reading apparatus 1 provided with a sheet-through type document feeder. FIG.

  In FIG. 1, a color image reading apparatus 1 has a contact glass 3 disposed on an upper surface portion of a main body housing 2, and a lamp 4 as a light source is provided inside the main body housing 2 below the contact glass 3. A first mirror 5, a second mirror 6, a third mirror 7, a lens 8, a CCD drive unit (SBU) 9, a scanner motor 10, a system control unit (SCU: see FIG. 2) 41, and the like are disposed.

  The lamp 4 and the first mirror 5 are mounted on the first carriage 12, and the second mirror 6 and the third mirror 7 are mounted on the second carriage 13. The lamp 4 and the first mirror 5 are driven by the scanner motor 10 to perform maximum scanning from the carriage home position. It is moved in the region direction (left-right direction in FIG. 1: sub-scanning direction).

  When reading a document set on the contact glass 3, the color image reading apparatus 1 is set on the contact glass 3 from the lamp 4 while moving the first carriage 12 and the second carriage 13 in the sub-scanning direction. The original is irradiated with light, the light reflected from the original is reflected by the first mirror 5 toward the second mirror 6, and further reflected by the second mirror 6 toward the third mirror 7. To reflect in the direction of the lens 8. The color image reading apparatus 1 condenses the light incident on the lens 8 on a CCD drive unit 9 and a CCD (Charge Coupled Device) 9a as a photoelectric conversion means mounted on the CCD drive unit 9 (see FIG. 3). ) Photoelectrically converts the incident light and outputs an analog image signal.

  Further, the color image reading apparatus 1 is provided with a white reference plate (not shown) outside the document area, and reads the white reference plate prior to reading the document and collects shading data including optical system distortion information. ·save.

  In the color image reading apparatus 1, an ARDF (automatic duplex document feeder) 20 is attached to the upper part of the main body housing 2, and the ARDF 20 is composed of a document table 21, a calling roller 22, a sheet feeding belt 23, a conveying roller 24, a separation roller. A roller 25, a first conveying roller 26, a reflection guide plate 27, a second conveying roller 28, a paper discharge roller 29, a reversing roller 30, a branching claw 31, a reversing table 32, and the like are provided, and the rear end of the document is detected. Document trailing edge detection sensor 33, width size detection board 34 for detecting document size, first document length sensor 35, second document length sensor 36, and set for detecting whether or not a document is set on document table 21 A sensor 37 and the like are provided, and the feeding mechanism of the calling roller 22, the sheet feeding belt 23, the conveying roller 24, and the separation roller 25 is driven by a sheet feeding motor (not shown). First transport roller 26, the reflection guide plate 27, the second conveying roller 28, the conveying mechanism of the sheet discharge roller 29 and the reverse roller 30, the transport motor 39a, driven by the paper feed / reversal motor 39 b (see FIG. 2).

  A DF document glass 38 is disposed at an upper portion of the main body housing 2 and facing the reflection guide plate 27.

  When the color image reading apparatus 1 uses the ARDF 20 to convey an original and read the original, the single-sided original reading is selected for the original stacked along the original guide 21a of the original table 21. In this case, the calling roller 22, the conveying roller 24 by the paper feeding belt 23, the separation roller 25, and the first conveying roller 26 pass through the reading position between the DF original glass 38 and the reflection guide plate 27, and then the second conveying roller. 28 and the paper discharge roller 29 to discharge the original. A registration sensor 14 is disposed in front of the DF original glass 38, and detects the timing of the entry (front end) and rear end of the original into the reading unit.

  Further, when double-sided document reading is selected, the color image reading apparatus 1 first reads the surface of the document as described above, and performs the same operation as when single-sided document reading is selected.

  That is, the calling roller 22, the sheet feeding belt 23 conveys the conveying roller 24, the separation roller 25, and the first conveying roller 26 passes through the reading position between the DF original glass 38 and the reflection guide plate 27, and the second conveying roller 28 and The paper is fed to the paper discharge roller 29 and the branching claw 31 is switched downward without being discharged, and is transferred onto the reverse table 32 by the reverse roller 30.

  The color image reading apparatus 1 switches the branching claw 31 upward after the trailing edge of the document passes through the paper discharge roller 29, temporarily stops the reverse roller 30, and then moves the reverse roller 30 in the direction opposite to the above. , The original is conveyed from the reversing table 32 toward the first conveying roller 26. The color image reading apparatus 1 further passes through the first conveyance roller 26 and the reading position between the DF original glass 38 and the reflection guide plate 27 in the same manner as the surface, and then passes through the second conveyance roller 28 and the discharge roller 29. The document is transported to the printer, and then the document is discharged.

  The color image reading apparatus 1 is moved to the vicinity of the reading position when the document passes through the reading position between the DF document glass 38 and the reflection guide plate 27 in both reading on the front surface and the back surface. The original is irradiated by the lamp 4, and the reflected light is reflected by the first mirror 5, the second mirror 6, and the third mirror 7, condensed by the lens 8 onto the CCD 9 a of the CCD drive unit 9, and incident on the CCD 9 a. Photoelectric conversion of light to RGB. Further, the color image reading device 1 reads the white reference plate and collects and stores the shading data in the same manner as the reading of the original on the contact glass 3 before starting the conveyance of the first original. As a plate, a dedicated white reference plate may be provided at a predetermined reference position, or the reflection guide plate 27 may be used as a white reference plate.

  The color image reading apparatus 1 includes the main body of the color image reading apparatus 1 and the ARDF 20 as shown in FIG. 2 which is an overall block diagram of the color image reading apparatus 1 and FIG. 3 which is a block configuration diagram of the main part of FIG. SCU (control means) 41, VIOB (signal processing means) 42, ADU 43, OIPU 44, NIC 45, ISIC 46, PSU (power supply unit) 47, power switch 48, plug 49, A scanner motor 50 and an SOP (operation panel) 51 are provided.

  The color image reading device 1 converts the reflected light of the original incident on the CCD 9a on the CCD drive unit 9 into analog signals of RGB colors having voltage values corresponding to the light intensity in the CCD 9a. Are output to the VIOB 42 by dividing into odd bits and even bits. The analog image signal of the CCD driving unit 9 is subjected to the analog processing circuit 42a on the VIOB 42 shown in FIG. 3 after the dark potential portion is removed, the odd bits and the even bits are combined, and the gain is adjusted to a predetermined amplitude. The signal is input to the A / D converter 42b and converted into a digital signal. The image signal digitized by the A / D converter 42b is subjected to shading correction by a shading unit (shading unit) 42c, subjected to image processing such as gamma correction and MTF correction by the IPU 41a on the SCU 41 from the VIOB 42, and then synchronized. A digital video signal together with a signal and an image clock is input to a memory controller 41b that manages an SDRAM (Synchronous Dynamic Random Access Memory) 41c, and is stored in an image memory including the SDRAM 41c. The digital image data stored in the SDRAM 41c is sent to the external I / F driver 41d and transferred to the external output device 200 such as a personal computer or a printer. The external I / F driver 41 is a generic term for drivers such as SCSI, IEEE 1394, LAN, and local video signals.

  Here, the shading correction is performed based on correction data calculated from the shading data held in the memory of the shading unit 42c.

  Although not shown, the SOP 51 includes various operation keys necessary for operating the color image reading apparatus 1 such as a start switch and a display unit such as an LCD (Liquid Crystal Display).

  On the SCU 41, in addition to the IPU 41a, the memory controller 41b, the SDRAM 41c and the external I / F driver 41d, a CPU (Central Processing Unit) 41e, a ROM (Read Only Memory) 41f, a RAM (Random Access Memory) 41g, an NVRAM ( Nonvolatile Random Access Memory) 41h, motor driver 41i, and the like are mounted, and the CPU 41e, via the motor driver 41i, the scanner motor 10, which is a stepping motor of the scanner body, the carry motor 39a of the ARDF 20, the paper feed motor / reverse motor The timing control of 39b is also performed.

  The input port connected to the CPU 41e on the SCU 41 is connected to the main body operation panel (SOP) 51 via the VIOB 42. Although not shown, various switches such as a start switch and a stop switch are mounted on the SOP 51. Has been. When each switch on the SOP 51 is pressed, the CPU 41e detects that the switch is turned on via the input port.

  The ADU 43 mounted on the ARDF 20 has a function of relaying the power supply of the electrical components used for the ARDF 20. The input port connected to the CPU 41e on the SCU 41 is connected to the operation panel (SOP) 51 of the color image reading apparatus 1 main body via the VIOB 42.

  The color image reading apparatus 1 includes a lamp power supply circuit 60 shown in FIG. 4. The lamp power supply circuit 60 includes a constant voltage power supply 61, an inverter circuit (drive means) 62, a lighting control circuit 63, a step-up transformer 64, and the like. And the lamp 4 is connected to the step-up transformer 64.

  The lighting control unit 63 receives a line synchronization signal TG-INV that defines the read start timing of each line, a clock signal CLK, a control signal CNT, and a gate signal GATE. The lighting control unit 63 is based on these signals. It operates to control the inverter circuit 62. The output of the inverter circuit 62 is applied to the lamp 4 via the step-up transformer 63. The control signal CNT is a signal for controlling ON / OFF of the lamp 4, and the gate signal GATE is a control signal for defining a lamp pause period.

  The inverter circuit 62 and the lighting control unit 63 are configured as shown in FIG. 5, for example, and include a switching element FET1 including a transistor Tr1, resistors R1, R2, a diode D1, a field effect transistor (Field Effect Transistor), and An inverter control IC (Integrated Circuit) 65 and the like are provided, and a control signal CNT that is a lamp ON / OFF control signal is input to the base of the transistor Tr1 through the resistor R1, and the control signal CNT is at a high level. At this time, the transistor Tr1 is turned on, and power is supplied to the inverter control IC 65. The inverter control IC 65 has a built-in driver for driving the switching element FET1, and oscillates at a predetermined cycle according to the clock signal CLK. The internal driver The switching element FET1 is driven by the output of the driver, and when the switching element FET1 is turned on by the drive signal, the current flows through the constant voltage power supply 61 → the primary winding of the step-up transformer 63 → the switching element FET1. And the energy is stored in the step-up transformer 63. Next, when the switching element FET1 is turned OFF, the current flowing in the step-up transformer 63 is cut off, and the energy stored in the step-up transformer 63 is released, and the step-up transformer 63 is released. A voltage waveform having a steep rise on the primary side and the secondary side of the transformer 63 is generated.

  This voltage waveform decays with time, and when the switching element FET1 is turned on and then turned off, a voltage waveform having a steep rise is generated again as described above.

  That is, each time the switching element FET1 is turned on / off, a voltage waveform having a steep rise is generated, a current repeatedly flows through the lamp 4, and the lamp 4 is turned on to emit light. That is, the inverter circuit 62 and the lighting control unit 63 drive and drive the lamp 4 at a lighting frequency corresponding to the frequency of the clock signal CLK.

  Further, the inverter control IC 65 stops the output during the period when the gate signal GATE is input.

  The timing chart of each of the above signals is shown in FIGS. 6 and 7, and FIG. 6 shows the timing of the control signal CNT for controlling ON / OFF of the lamp 4 and the line synchronization signal TG-INV. Accordingly, the line synchronization signal TG-INV is supplied for the purpose of synchronizing the lighting frequency separately from the control signal CNT.

  Note that the control signal CNT and the line synchronization signal TG-INV are supplied asynchronously, and the ON / OFF of the control signal CNT is an arbitrary time.

  FIG. 7 shows the timing of the line synchronization signal TG-INV, the gate signal GATE, the clock signal CLK, and the inverter output (light waveform). In FIG. 7, T1 and T2 are lamp pause periods, The number of lighting pulses per line can be set to an arbitrary value by providing this pause period according to the required document surface illuminance.

  In FIG. 7, the lamp lighting pulse generation timing in the main scanning direction is arbitrarily controlled by controlling the gate signal GATE to control the end timing of the lamp pause period and the clock signal CLK to switch the lamp lighting pulse generation timing. Can do.

  Then, the color image reading apparatus 1 controls the lighting of the lamp 4 that is a light source by the light source control circuit 70 shown in FIG. In FIG. 8, a light source control circuit 70 includes the CCD 9a, the A / D conversion circuit 71 and the image data comparison unit 71, a CLK idle period calculation unit 72, and an inverter circuit 62, and controls the lighting of the lamp 4, which is a light source. I do. Note that the image data comparison unit 71 and the CLK idle period calculation unit 72 are configured by, for example, the CPU 41e of the SCU 41 executing a CLK idle period control program stored in the ROM 41f.

  As described above, the CCD 9a converts the reflected light from the original into analog signals (analog image data) of RGB colors having voltage values corresponding to the light intensity, and divides them into odd bits and even bits, as shown in FIG. The analog processing circuit 42a removes the dark potential portion from the analog image data, combines it into odd bits and even bits, and adjusts the gain to a predetermined amplitude. / D input to the D converter 42b. The A / D converter 42b converts the input analog image data into digital image data, and outputs the digital image data to the image processing unit at the subsequent stage of the shading unit 42c and also to the image data comparison unit 71.

  The image data comparison unit 71 compares the CCD target value and the measured image data by comparing the preset CCD target value (target value) with the measured image data (measured image data) input from the A / D converter 42b. Are not equal, the target value difference Δβ between the CCD target value and the measured image data is output to the CLK pause period calculation unit 72, and the CLK pause period calculation unit 72 outputs the target value difference between the CCD target value and the measured image data. Based on Δβ, the idle period of the clock signal CLK of one line for driving the lamp 4 input to the inverter circuit 62 (hereinafter simply referred to as CLK idle period) is calculated, and the calculated CLK idle period Is output to the inverter circuit 62. This CLK pause period determines a lamp pause period, which is a lighting pause period of the lamp 4. As described above, the inverter circuit 62 pauses lighting of the lamp 4 only during the CLK pause period from the CLK pause period calculation unit 72. This CCD target value is a target value when a density reference plate (for example, a white reference plate) is read by the CCD 9a, and differs depending on the reading mode (color mode, black and white mode, etc.) of the image reading apparatus 1, and image reading It depends on the type of device. Therefore, the CCD target value is appropriately set according to the color image reading device 1 and the mode.

  That is, the rest period when the lamp 4 is lit and the light emission amount (light source light emission amount) of the lamp 4 are excluding the temperature factor, the relationship of CLK pause period decrease → light source light emission increase, CLK pause period increase → light source light emission decrease There is.

  Therefore, the CLK idle period calculation unit 72 stores the CLK idle period calculation program and the CLK idle period change amount table, for example, a target value (target value) difference Δβ (digit) and the target value difference as shown in FIG. A CLK idle period change amount table corresponding to a CLK idle period change amount Δt (μs) to be selected by Δβ is stored in advance, a target value difference Δβ is calculated by a CLK idle period calculation program, and the target value difference Δβ is determined. The clock signal CLK having the CLK idle period obtained by reading the CLK idle period change amount Δt from the CLK idle period change amount table and adding the read CLK idle period change amount Δt to the current CLK idle period t Is output to the inverter circuit 62. In FIG. 9, the target value difference Δβ between the numerical values of the target value differences Δβ in the CLK pause period change amount table is the target value difference Δβ that selects the larger CLK pause period change amount Δt. To do.

  That is, when the target value (CCD target value) after the density reference plate is read by the CCD 9a and A / D converted is α, and the actual measured value of the CCD 9a after A / D conversion is β, the image data The comparison unit 71 calculates Δβ = α−β, obtains a difference (target value difference) Δβ with respect to the CCD target value (target value), and outputs the difference to the CLK pause period calculation unit 72. The CLK inactivity period calculator 72 obtains the CLK inactivity period change amount Δt from the CLK inactivity period change amount table based on the target value difference Δβ.

  At this time, the image data comparison unit 71 compares the CCD target value set in advance with the image data (actual measurement value). If the CCD target value and the image data that is the actual measurement value are equal, As a target value difference Δβ with respect to the image data, “0” is output to the CLK pause period calculation unit 72, and the CLK pause period calculation unit 72 sets the target value difference Δβ between the CCD target value and the actually measured image data to “0”. Therefore, the clock signal CLK in the same CLK idle period as before is output to the inverter circuit 62. The inverter circuit 62 drives the lamp 4 to turn on in the CLK pause period corresponding to the clock signal CLK from the CLK pause period calculation unit 72.

  Next, the operation of this embodiment will be described. The color image reading apparatus 1 according to the present embodiment controls the CLK pause period (lamp pause period) of the lamp 4 based on the image data value read by the CCD 9a to stabilize the light amount of the lamp 4 at a target value, and At the start of lighting start of No. 4, the CLK pause period is appropriately controlled from the CLK pause period longer than the CLK pause period at the maximum light amount, which is set in advance as the CLK pause period at the maximum light amount, and is quickly increased and exceeded. The document is read stably while suppressing the chute.

  That is, in the color image reading apparatus 1, when a document is set on the document table 21 of the ARDF 20, a setting operation necessary for reading the document is performed by the SOP 51, and the start switch is turned on, the CPU 41e is shown in FIG. As described above, the clock signal CLK having the CLK idle period longer than the preset maximum light quantity CLK idle period is output to the inverter circuit 62 at the lighting frequency at the maximum light quantity, and is output to the inverter circuit 62 at the maximum light quantity. The lamp 4 is driven to be lit by the clock signal CLK having the lighting frequency at the maximum light amount which is longer than the CLK suspension period (step S101). When the light quantity of the lamp 4 that is lit and driven by the clock signal CLK in the longer CLK idle period is longer, the CCD 9 The output analog image data of the capturing image data obtained by digital conversion at A / D converter 42b (step S102). As described above, the maximum light intensity CLK suspension period is a normal CLK light suspension period at the time of the maximum maximum light amount which is preset as a CLK suspension period when the lamp 4 is turned on with the maximum light amount.

  When the color image reading apparatus 1 reads the actual measurement image data that is the actual measurement value, the image data comparison unit 71 compares the actual measurement image data with the CCD target value to calculate the target value difference Δβ (step S103). If the target value difference Δβ is not “0” and there is a target value difference Δβ between the measured image data and the CCD target value, the CLK pause period calculation unit 72 changes the CLK pause period change amount of the ROM 41f shown in FIG. With reference to the table, the CLK pause period of the clock signal CLK in one line is calculated based on the target value difference Δβ (step S104).

  That is, now, assuming that the CCD target value is α and digitally measured actual image data is β, the image data comparison unit 71 calculates the target value difference Δβ from the following equation.

Δβ = α-β
When calculating the target value difference Δβ, the image data comparison unit 71 outputs the calculated target value difference Δβ to the CLK pause period calculation unit 72, and the CLK pause period calculation unit 72 is input from the image data comparison unit 71. Based on the target value difference Δβ, the CLK idle period change amount table of the ROM 41f is referred to, and the CLK idle period change amount (CLK idle period change amount) Δt (μs) of the clock signal CLK is calculated. For example, if the target value difference Δβ = −26, No. in the CLK pause period change amount table. A value corresponding to “−30” of 2, Δt = 3.0 μs is selected. In this case, if the current CLK idle period (CLK idle period of the clock signal CLK) t is t = 4.0 μs, the CLK idle period of the calculated clock signal CLK is t + Δt = 7.0 μs, and the lamp 4 As a result, the CLK idle period increases and the light is dimmed.

  Further, if Δβ = 15, No. in the CLK pause period change amount table. A value corresponding to “10” of 6 is selected, Δt = −1.0 μs. In this case, if the current CLK suspension period t is t = 4.0t, the CLK suspension period of the clock signal CLK after the calculation is t + Δt = 3.0t, and the CLK suspension period of the lamp 4 is reduced. It will brighten.

  The CLK idle period calculator 72 outputs the calculated clock signal CLK of the CLK idle period to the inverter circuit 62, and the inverter circuit 62 drives the lamp 4 to light up in the CLK idle period corresponding to the clock signal CLK.

  In this case, the light amount gradually approaches the target light amount from the clock signal CLK in the CLK pause period which is the lighting frequency at the maximum light amount at the start of lighting and is longer than the initial CLK pause period at the preset maximum light amount. Controls the CLK pause period of the clock signal CLK.

  At this time, in order to prevent the light quantity of the lamp 4 from overshooting, the CLK pause period is set to the target CLK pause period as the actually measured image data approaches the CCD target value, that is, as the light quantity approaches the target light quantity. Gradually approach the difference to make it smaller.

  When the CPU 41e changes the CLK pause period of the clock signal CLK and changes the pause period of the lamp 4 that is lit, the CPU 41e returns to step S102 and reads the image data by the CCD 9a again, The process of comparing the CCD target values is repeated in the same manner as described above (steps S102 to S104). When the actually measured image data and the CCD target values match in step S103, the ramp is stopped without changing the CLK pause period of the clock signal CLK. 4 is turned on, and the reading operation is started to read the document set on the document table 21 (step S105).

  When the reading of the document is completed, the CPU 41e turns off the lamp 4 and ends the process (step S106).

  As described above, the color image reading apparatus 1 according to the present embodiment starts lighting the lamp 4 in the CLK pause period longer than the CLK pause period at the maximum light amount at the start of lighting. Is compared with the CCD target value to control the CLK idle period of the clock signal CLK for driving the lamp 4 that determines the idle period of the lamp 4 that is lit.

  Therefore, even when the light amount of the lamp 4 (that is, the output of the CCD 9a) is different depending on the mode or the like, that is, when the target CCD output is different, the target CCD can be quickly and inexpensively while suppressing overshoot. The output (CCD target value) can be stabilized, versatility and usability can be improved without changing the lamp 4 and the inverter circuit 62, and the image quality of the read image can be improved.

  That is, in the prior art in which the CLK pause period of the clock signal CLK for driving the lamp 4 is lit at a predetermined constant CLK pause period t0, for example, as shown in FIG. With respect to the output (CCD target value), the CCD output once reaches the target output, and then overshoots a predetermined amount and stabilizes to the target CCD output, so that the light quantity of the lamp 4 is stable and the output of the CCD 9a is stable. It took a long time to do.

  However, in the color image reading apparatus 1 according to the present embodiment, as described above, at the start of lighting, the lamp 4 is turned on during the CLK pause period with the maximum light amount, and then the image data (read by the CCD 9a with the light amount of the lamp 4) (Actually measured value) is compared with the CCD target value to control the CLK pause period of the clock signal CLK for driving the lamp 4 that determines the pause period of the lamp 4 that is lit. For example, as shown in FIG. Based on the actually measured image data, the CLK pause period of the clock signal CLK of the lamp 4 is gradually changed from the CLK pause period t1 longer than the CLK pause period at the maximum light amount to the CLK pause periods t2, t3, etc. When the target CLK light amount (that is, the output of the CCD 9a) varies depending on the mode or the like when the target CLK pause period t0 is controlled, That is, even when the target CCD output is different, overshoot can be suppressed and the target CCD output (CCD target value) can be stabilized quickly and inexpensively, and the lamp 4 and the inverter circuit 62 can be changed. In addition, versatility and usability can be improved, and the image quality of the read image can be improved.

  Further, the color image reading apparatus 1 compares the actually measured image data read by the CCD 9a with the CCD target value, and controls the CLK pause period of the clock signal CLK based on the comparison result.

  Therefore, it is possible to adjust the light quantity of the lamp 4 at low cost and with high accuracy based on the actually measured image data of the CCD 9a, to improve versatility and usability, and to improve the image quality of the read image. Can do.

  Further, the color image reading device 1 calculates a target value difference Δβ between the actually measured image data of the CCD 9a and the CCD target value, and sets a CLK pause period of the clock signal CLK for driving the lamp 4 based on the target value difference Δβ. I have control.

  Therefore, the light quantity of the lamp 4 can be adjusted at low cost and with high accuracy while suppressing overshoot based on the actually measured image data of the CCD 9a, and versatility and usability can be improved. The image quality of the image can be improved.

  Further, the color image reading apparatus 1 uses an inverter circuit 62 for lighting the lamp 4 at a lighting frequency corresponding to the frequency of the input pulse as a driving circuit (driving means) for the lamp 4, and is an input pulse to the inverter circuit 62. The lighting suspension period of the lamp 4 is controlled by controlling the CLK suspension period of the clock signal CLK.

  Therefore, the light quantity of the lamp 4 can be adjusted at low cost and with high accuracy while suppressing overshoot, and versatility and usability can be improved, and the image quality of the read image can be improved. it can.

  13 to 15 are diagrams showing a second embodiment of the image reading apparatus of the present invention. FIG. 13 is a color image reading apparatus to which the second embodiment of the image reading apparatus and the image processing apparatus of the present invention is applied. FIG. 80 is a light source control circuit diagram 80 of FIG.

  The present embodiment is applied to a color image reading apparatus similar to the color image reading apparatus 1 of the first embodiment. In the description of this embodiment, the same components as those of the first embodiment are described. Are given the same reference numerals, and detailed description thereof is omitted, and parts not shown in the drawings are described using the reference numerals used in the description of the first embodiment as they are, if necessary.

  In FIG. 13, the light source control circuit 80 includes a CCD 9a, an A / D converter 42b, an image data comparison unit 71, and an inverter circuit 62, and also includes a CLK idle period switching unit 81. Perform lighting control. Note that the image data comparison unit 71 and the CLK idle period switching unit 81 are configured by the CPU 41e of the SCU 41 executing a CLK idle period control program stored in the ROM 41f, for example.

  As described above, the CCD 9a converts the reflected light from the original into analog image data of RGB colors having voltage values corresponding to the light intensity, and the gain is adjusted to a predetermined amplitude by the analog processing circuit 42a of FIG. Thereafter, the data is input to the A / D converter 42b. The A / D converter 42b converts the analog image data into digital image data, and outputs the digital image data to the image processing unit subsequent to the shading unit 42c. Output to.

  The image data comparison unit 71 compares a preset CCD target value (target value) with actual image data (actual image data) input from the A / D converter 42b, and compares the comparison result with the CLK pause period switching unit. 81.

  The CLK idle period switching unit 81 sets the CLK idle period of the clock signal CLK supplied to the inverter circuit 62 as the initial CLK idle period t1 and the target CLK idle period t0 based on the comparison result between the CCD target value and the measured image data. The clock signal CLK during the CLK idle period is output to the inverter circuit 62. That is, when there is a difference between the CCD target value and the measured image data, the CLK idle period switching unit 81 selects the initial CLK idle period t1 as the CLK idle period of the clock signal CLK, and the initial CLK idle period When the clock signal CLK of t1 is output to the inverter circuit 62 and the actually measured image data matches the CCD target value, the target time CLK inactive period t0 is selected as the CLK inactive period of the clock signal CLK, and the target time CLK inactive period The clock signal CLK at t0 is output to the inverter circuit 62. The initial CLK pause period t1 is a CLK pause period shorter than the target time CLK pause period t0 in order to quickly increase the light quantity of the lamp 4 to the target light quantity while preventing overshoot. The target time CLK pause period t0 is a CLK pause period in which the lamp 4 irradiates the target light amount, and differs depending on the reading mode (color mode, black and white mode, etc.) of the image reading apparatus 1, and the type of the image reading apparatus, etc. It depends on the situation.

  The inverter circuit 62 drives the lamp 4 to light at a lighting frequency corresponding to the clock signal CLK having the CLK pause period from the CLK pause period calculator 72.

  Next, the operation of this embodiment will be described. The color image reading apparatus 1 according to the present embodiment starts lighting the lamp 4 with the clock signal CLK in the initial CLK pause period, and then the CLK pause period (lamp pause period) of the lamp 4 based on the image data value read by the CCD 9a. Period) to the target time CLK idle period.

  That is, in the color image reading apparatus 1, when a document is set on the document table 21 of the ARDF 20, a setting operation necessary for reading the document is performed by the SOP 51, and the start switch is turned on, the CPU 41e is shown in FIG. As described above, the preset clock signal CLK of the initial CLK idle period t1 is output to the inverter circuit 62, and the inverter circuit 62 is driven to light the lamp 4 at the lighting frequency of the initial CLK idle period t1 (step S201). The actual measurement image data read by the CCD 9a and digitally converted by the A / D converter 42b is taken in (step S202).

  When the color image reading apparatus 1 captures the measured image data, the image data comparison unit 71 compares the measured image data (read value) with the CCD target value (target value) and checks whether there is a difference between the two ( In step S203), if there is a difference between the measured image data and the CCD target value, the process returns to step S202, and the measured image data read by the CCD 9a and digitally converted by the A / D converter 42b is taken in again. The process of comparing with the value is sequentially repeated (steps S202 and S203).

  When the actually measured image data and the CCD target value match in step S203, the CLK pause period switching unit 81 selects the target CLK pause period t0 as the CLK pause period of the clock signal CLK, and the target time CLK pause period t0. The clock signal CLK is output to the inverter circuit 62, and the inverter circuit 62 drives the lamp 4 to be lit at a lighting frequency according to the clock signal CLK of the target time CLK suspension period t 0 from the CLK suspension period switching unit 81.

  The CPU 41e starts the reading operation when the measured image data and the CCD target value match, and the lamp 4 is turned on by switching the CLK suspension period of the clock signal CLK from the initial CLK suspension period t1 to the target CLK suspension period t0. Then, the document set on the document table 21 is read (step S205), and when reading of the document is completed, the lamp 4 is turned off and the process is terminated (step S206).

  In this way, as shown in FIG. 15, the color image reading apparatus 1 causes the lamp 4 to be turned on with the clock signal CLK of the predetermined initial CLK pause period t1 shorter than the CLK pause period at the target light quantity when the lamp 4 starts to be lit. When the measured image data read by the CCD 9a is taken in and the measured image data becomes the CCD target value, the CLK pause period of the clock signal CLK, that is, the pause period of the lit lamp 4 is set as the target CLK pause period. The lamp 4 is turned on by switching to t0.

  Therefore, even when the required target light amount is different, the light amount of the lamp 4, that is, the output of the CCD 9a can be stabilized to the target CCD output more quickly and quickly while suppressing overshoot. In addition, versatility and usability can be improved without changing the inverter circuit 62 and the image quality of the read image can be improved.

  16 to 18 are diagrams showing a third embodiment of the image reading apparatus and the image processing apparatus of the present invention, and FIG. 16 applies the third embodiment of the image reading apparatus and the image processing apparatus of the present invention. FIG. 90 is a light source control circuit diagram 90 of the color image reading apparatus.

  The present embodiment is applied to a color image reading apparatus similar to the color image reading apparatus 1 of the first embodiment. In the description of this embodiment, the same components as those of the first embodiment are described. Are given the same reference numerals, and detailed description thereof is omitted, and parts not shown in the drawings are described using the reference numerals used in the description of the first embodiment as they are, if necessary.

  In FIG. 16, the light source control circuit 90 includes a CCD 9a, an analog processing circuit (analog signal processing means) 42a of a VIOB (signal processing means) 42, an A / D converter 42b, an image data comparison unit 71, and an inverter circuit 62. In addition, an analog gain calculation circuit 91 is provided, and the size of the analog image data output from the CCD 9a is adjusted by changing the analog gain value for gain adjustment in the analog signal processing circuit 42a. Note that the image data comparison unit 71 and the analog gain calculation circuit 91 are configured by, for example, the CPU 41e of the SCU 41 executing a CCD output control program stored in the ROM 41f.

  As described above, the CCD 9a converts the reflected light from the original into RGB analog image data having voltage values corresponding to the light intensity, and inputs the analog image data to the analog processing circuit 42a on the VIOB 42. The analog processing circuit 42a Removes the dark potential portion, synthesizes the odd and even bits, and adjusts (amplifies) the gain based on the gain setting value from the CPU 41e (analog gain calculation circuit 91), and then outputs it to the A / D converter 42b. To do. The A / D converter 42b converts the analog image data whose gain has been adjusted by the analog processing circuit 42a into digital image data, and outputs the digital image data to the subsequent image processing unit and also to the image data comparison unit 71. To do.

  The image data comparison unit 71 compares a preset CCD target value (target value) with gain-adjusted actual image data (actual image data) input from the A / D converter 42b, and compares the difference between the comparison results. Is output to the analog gain calculation circuit 91.

  The analog gain calculation circuit 91 determines an analog gain value to be set in the analog processing circuit 42a based on a difference that is a comparison result between the CCD target value and the measured image data, and outputs the analog gain value to the analog signal processing circuit 42a.

  That is, the analog gain calculation circuit 91 selects, in the ROM 41f, an analog gain calculation program and an analog gain change amount table, for example, a target value (target value) difference Δβ (digit) and the target value difference Δβ as shown in FIG. The analog gain change amount table corresponding to the analog gain change amount ΔG (times) to be stored is stored in advance, the target value difference Δβ is calculated by the analog gain calculation program, and the analog gain change amount ΔG corresponding to the target value difference Δβ is calculated. Is read from the analog gain change amount table, and the analog gain value G (= G + ΔG) obtained by adding the read analog gain change amount ΔG to the current analog gain value G is output to the analog processing circuit 42a as the changed analog gain value G. . In FIG. 17, the target value difference Δβ between the numerical values of the target value differences Δβ in the analog gain change amount table employs a target value difference Δβ that selects the larger analog gain change amount ΔG.

  That is, the target value (CCD target value) of the value after the density reference plate is read by the CCD 9a and A / D converted is α, the analog gain is adjusted by the analog processing circuit 42 after being read by the CCD 9a, and is digitally converted by the A / D converter 42b. When the converted current read image data (actually measured value) is β, the image data comparison unit 71 calculates a target value difference Δβ = α−β and outputs it to the analog gain calculation circuit 91 for analog gain calculation. The circuit 91 obtains an analog gain change amount ΔG from the analog gain change amount table based on the target value difference Δβ.

  At this time, the image data comparison unit 71 compares the CCD target value set in advance with the image data (actual measurement value). If the CCD target value and the image data that is the actual measurement value are equal, “0” is output to the analog gain calculation circuit 91 as the target value difference Δβ with respect to the image data, and the analog gain calculation circuit 91 has a target value difference Δβ between the CCD target value and the actually measured image data of “0”. Therefore, the same analog gain value G as before is output to the analog processing circuit 42a. The analog processing circuit 42a adjusts the gain of the analog image data from the CCD 9a to an amplitude based on the analog gain value G from the analog gain calculation circuit 91, and outputs it to the A / D converter 42b.

  Next, the operation of this embodiment will be described. The color image reading apparatus 1 of the present embodiment adjusts the image data processing of the actually measured image data based on the actually measured image data read by the CCD 9a, in particular, the analog gain, and sets the image data output from the CCD 9a to the target value (CCD (Target value).

  That is, in the color image reading apparatus 1, when a document is set on the document table 21 of the ARDF 20, a setting operation necessary for reading the document is performed by the SOP 51, and the start switch is turned on, the CPU 41e is shown in FIG. As described above, a clock signal CLK having a preset initial frequency is output to the inverter circuit 62, and the inverter circuit 62 is driven to turn on the lamp 4 at the initial frequency (step S301). This initial frequency is a frequency at which the lamp 4 is lit with the maximum light amount.

  The color image reading apparatus 1 inputs analog image data output from the CCD 9a to the analog processing circuit 42a when the light amount of the lamp 4 to be lit is on. The analog processing circuit 42a receives analog image data input from the CCD 9a. The dark potential portion is removed from the signal, and the gain is adjusted with the initial analog gain setting value from the analog gain calculation circuit 91 constructed by the CPU 41e, and then output to the A / D converter 42b. The A / D converter 42b converts the analog image data whose gain has been adjusted by the analog processing circuit 42a into digital image data, and outputs the digital image data to the image data comparison unit 71 as measured image data (step S302).

  This initial analog gain value is a gain value that appropriately adjusts the gain of the read value of the CCD 9a by the lamp 4 that is lit at the maximum light amount when it is lit.

  The color image reading device 1 adjusts the analog gain of the image data read by the CCD 9a in the analog processing circuit 42a with the analog gain value, converts the image data into a digital value by the A / D converter 42b, and takes it into the image data comparison unit 71 as the measured image data. Then, the image data comparison unit 71 compares the measured image data with the CCD target value to calculate the target value difference Δβ (step S303). The analog gain calculation circuit 91 is shown in FIG. 17 when the target value difference Δβ calculated by the image data comparison unit 71 is not “0” and there is a target value difference Δβ between the measured image data and the CCD target value. With reference to the analog gain change amount table in the ROM 41f, the analog gain value of the analog processing circuit 42a is calculated based on the target value difference Δβ (step S304).

  That is, now, assuming that the CCD target value is α and digitally measured actual image data is β, the image data comparison unit 71 calculates the target value difference Δβ from the following equation.

Δβ = α-β
When calculating the target value difference Δβ, the image data comparison unit 71 outputs the calculated target value difference Δβ to the analog gain calculation circuit 91, and the analog gain calculation circuit 91 receives the target value input from the image data comparison unit 71. Based on the difference Δβ, the analog gain change amount table in the ROM 41f is referred to, and the analog gain set value change amount (analog gain change amount) ΔG (times) of the analog processing circuit 42a is calculated. For example, if the target value difference Δβ = −26, No. in the analog gain change amount table. 2. A value corresponding to “−30” of 2, ΔG = −0.6 times is selected. In this case, if the current analog gain value G is G = 1.0 times, the calculated analog gain value G becomes G + ΔG = 0.4 times, and the analog gain value G in the analog processing circuit 42a decreases. As a result, the image data becomes smaller.

  If Δβ = 15, No. in the analog gain change amount table. A value corresponding to “10” of 6 and ΔG = + 0.2 times are selected. In this case, if the current analog gain value G is G = 1.0G, the calculated analog gain value G becomes G + ΔG = 1.2 times, and the analog gain value G of the analog processing circuit 42a increases. The image data becomes large.

  The analog gain calculation circuit 91 outputs the calculated analog gain value G to the analog processing circuit 42a, and the analog processing circuit 42a adjusts the gain of the image data with the analog gain value G.

  When the analog gain calculation circuit 91 changes the setting value of the analog gain of the analog processing circuit 42a, the color image reading apparatus 1 returns to step S302, reads the image data by the CCD 9a again, and converts the measured image data into analog data. The processing circuit 42a adjusts the gain with the changed analog gain value, digitally converts it with the A / D converter 42b, and repeats the same processing from the process of comparing the digitally converted actual measured image data with the CCD target value (as described above). In step S302 to S304), when the actually adjusted image data whose gain has been adjusted and the CCD target value coincide with each other in step S303, the reading operation is started without changing the analog gain value of the analog processing circuit 42a, and the document table 21 is loaded. The set original is read (step S305).

  When completing the reading of the document, the CPU 41e turns off the lamp 4 and ends the processing (step S306).

  As described above, when the color image reading apparatus 1 of the present embodiment starts lighting, the image data read by the CCD 9a fluctuates even if reading is performed by the lamp 4 having the maximum light amount, but the image data read by the CCD 9a is changed. The analog gain value of the analog processing circuit 42a for gain adjustment is adjusted so that the actually measured image data after the analog gain adjustment becomes the CCD target value.

  Therefore, even when the target light quantity of the lamp 4 differs depending on the mode or the like, that is, when the target CCD output is different, the target CCD output (CCD target value) is stabilized quickly and inexpensively while suppressing overshoot. Therefore, versatility and usability can be improved without changing the lamp 4 and the inverter circuit 62, and the image quality of the read image can be improved.

  19 to 21 are views showing a fourth embodiment of the image reading apparatus of the present invention, and FIG. 19 is a color image reading apparatus to which the fourth embodiment of the image reading apparatus and the image processing apparatus of the present invention is applied. FIG. 100 is a light source control circuit diagram 100 of FIG.

  The present embodiment is applied to a color image reading apparatus similar to the color image reading apparatus 1 of the first embodiment. In the description of this embodiment, the same components as those of the first embodiment are described. Are given the same reference numerals, and detailed description thereof is omitted, and parts not shown in the drawings are described using the reference numerals used in the description of the first embodiment as they are, if necessary.

  19, the light source control circuit 100 includes a CCD 9a, an analog processing circuit 42a of a VIOB (signal processing means) 42, an A / D converter (digital conversion means) 42b, an image data comparison section 71, and an inverter circuit 62. A reference voltage calculation circuit 101 and a D / A converter 102 are provided to adjust the size of analog image data output from the CCD 9a. The image data comparison unit 71, the reference voltage calculation circuit 101, and the D / A converter 102 are configured by, for example, the CPU 41e of the SCU 41 executing a CCD output control program stored in the ROM 41f.

  As described above, the CCD 9a converts the reflected light from the original into RGB analog image data having voltage values corresponding to the light intensity, and inputs the analog image data to the analog processing circuit 42a on the VIOB 42. The analog processing circuit 42a Removes the dark potential portion, synthesizes odd and even bits, adjusts the gain to the amplitude based on the gain value from the CPU 41e, and then outputs it to the A / D converter 42b. The A / D converter 42b compares the analog image data whose gain has been adjusted by the analog processing circuit 42a with the reference voltage set by the reference voltage calculation circuit 101 that is functionally configured by the CPU 41e, thereby converting the digital image data into digital image data. The image is converted and output to the subsequent image processing unit of the shading unit 42 c and also output to the image data comparison unit 71.

  The image data comparison unit 71 compares the CCD target value (target value) set in advance with the measured image data (measured image data) digitally converted according to the reference voltage input from the A / D converter 42b. The difference between the comparison results is output to the reference voltage calculation circuit 101.

  The reference voltage calculation circuit 101 calculates a reference voltage value to be set in the A / D converter 42b based on the difference that is a comparison result between the CCD target value and the measured image data, and the A / D converter 102 performs A / D output to the D converter 42b. The D / A converter 102 converts the digital reference voltage value calculated by the reference voltage calculation circuit 101 into an analog reference voltage value, and sets the analog reference voltage value in the A / D converter 42b.

  That is, the reference voltage calculation circuit 101 selects, in the ROM 41f, a reference voltage calculation program and a reference voltage change amount table, for example, a target value (target value) difference Δβ (digit) and the target value difference Δβ as shown in FIG. A reference voltage change amount table corresponding to the reference voltage change amount ΔVref (V) to be stored is stored in advance, the target value difference Δβ is calculated by the reference voltage calculation program, and the reference voltage change amount ΔVref corresponding to the target value difference Δβ is calculated. Is read from the reference voltage change amount table, and the reference voltage V (= V + ΔV) obtained by adding the read reference voltage change amount ΔVref to the current reference voltage V is used as the reference voltage after change to the A / D via the D / A converter 102. Output to the converter 42b. In FIG. 20, the target value difference Δβ between the numerical values of the target value differences Δβ in the reference voltage change amount table employs a target value difference Δβ that selects the larger reference voltage change amount ΔVref.

  That is, the target value (CCD target value) of the value after the density reference plate is read by the CCD 9a and A / D converted is α, the gain is read by the analog processing unit 42a by the CCD 9a, and the reference voltage is read by the A / D converter 42b. When the current read image data (actually measured value) digitally converted in (3) is β, the image data comparison unit 71 calculates the target value difference Δβ = α−β, and outputs it to the reference voltage calculation circuit 101 to obtain the reference voltage. The arithmetic circuit 101 obtains the reference voltage change amount ΔVref from the reference voltage change amount table based on the target value difference Δβ.

  At this time, the image data comparison unit 71 compares the CCD target value set in advance with the image data (actual measurement value). If the CCD target value and the image data that is the actual measurement value are equal, “0” is output to the reference voltage calculation circuit 101 as the target value difference Δβ with respect to the image data, and the reference voltage calculation circuit 101 has a target value difference Δβ between the CCD target value and the actually measured image data of “0”. Therefore, the same reference voltage V as before is output to the A / D converter 42b via the D / A converter 102. The A / D converter 42b compares the analog image data read and gain-adjusted by the CCD 9a from the analog processing circuit 42a with the reference voltage value V from the reference voltage calculation circuit 101 and converts it into analog image data. The data is output to the image data comparison unit 71.

  Next, the operation of this embodiment will be described. The color image reading apparatus 1 according to the present embodiment controls the reference voltage when image data processing of the actual measurement image data, particularly digital conversion by the A / D converter 42b, based on the actual measurement image data read by the CCD 9a. The image data output from the CCD 9a is stabilized at a target value (CCD target value).

  That is, in the color image reading apparatus 1, when a document is set on the document table 21 of the ARDF 20, a setting operation necessary for reading the document is performed by the SOP 51, and the start switch is turned on, the CPU 41e is shown in FIG. As described above, a clock signal CLK having a preset initial frequency is output to the inverter circuit 62, and the inverter circuit 62 is driven to light the lamp 4 at the initial frequency (step S401). This initial frequency is a frequency at which the lamp 4 is lit with the maximum light amount.

  The CCD 9a outputs analog image data with the amount of light from the lit lamp 4 to the analog processing circuit 42a. The analog processing circuit 42a removes the dark potential portion from the analog image data input from the CCD 9a, and the CPU 41e. After the gain is adjusted with the gain value from, the signal is output to the A / D converter 42b. The A / D converter 42b receives the analog image data whose gain has been adjusted by the analog processing circuit 42a as an initial reference voltage that is set and input via the D / A converter 102 from the reference voltage calculation circuit 101 that is functionally constructed by the CPU 41e. Compared with V, it is converted into digital image data and is taken into the image data comparison unit 71 (step S402).

  This initial reference voltage is a reference voltage value for appropriately digitally converting the value of the analog read image data of the CCD 9a by the lamp 4 that is lit at the maximum light amount when it is lit.

  When the color image reading device 1 reads the image data, converts it into digital data, and takes it in the image data comparison unit 71 as actual measurement image data, the image data comparison unit 71 compares the actual measurement image data with the CCD target value to obtain a target. The value difference Δβ is calculated (step S403). If the target value difference Δβ is not “0” and there is a target value difference Δβ between the measured image data and the CCD target value, the reference voltage calculation circuit 101 Referring to the reference voltage change amount table of ROM 41f shown in FIG. 20, the reference voltage value of A / D converter 42b is calculated based on the target value difference Δβ (step S404).

  That is, now, assuming that the CCD target value is α and digitally measured actual image data is β, the image data comparison unit 71 calculates the target value difference Δβ from the following equation.

Δβ = α-β
When the target value difference Δβ is calculated, the image data comparison unit 71 outputs the calculated target value difference Δβ to the reference voltage calculation circuit 101, and the reference voltage calculation circuit 101 receives the target value input from the image data comparison unit 71. Based on the difference Δβ, the reference voltage change amount table of the ROM 41f is referred to, and the reference voltage value change amount (reference voltage change amount) ΔVref (V) of the A / D converter 42b is calculated. For example, when the target value difference Δβ = −26, No. in the reference voltage change amount table. A value corresponding to “−30” of 2, ΔVref = 0.6V is selected. In this case, if the current reference voltage value V is V = 1.0V, the calculated reference voltage value V becomes V + ΔVref = 1.6V, and the reference voltage value in the A / D converter 42b becomes high. The image data becomes smaller.

  If Δβ = 15, No. in the reference voltage change amount table. A value corresponding to “10” of 6 and ΔVref = −0.2 V are selected. In this case, if the current reference voltage value V is V = 1.0V, the calculated reference voltage value V becomes V + ΔVref = 0.8V, and the reference voltage value of the A / D converter 42b becomes low. The image data becomes large.

  The reference voltage calculation circuit 101 converts the calculated reference voltage value into analog by the D / A converter 102 and outputs it to the A / D converter 42b. The A / D converter 42b compares the image data with the reference voltage value and performs digital conversion. To do.

  When the reference voltage calculation circuit 101 changes the set value of the reference voltage of the A / D converter 42b, the color image reading apparatus 1 returns to step S402, and reads the image data by the CCD 9a again to measure the measured image data. Is digitally converted by the A / D converter 42b with the changed reference voltage value, and the digitally converted actual measured image data and the CCD target value are compared and repeated in the same manner as above (steps S402 to S404). In S403, when the actually converted digital image data and the CCD target value match, the reading operation is started without changing the reference voltage value of the A / D converter 42b, and the document set on the document table 21 is started. Reading is performed (step S405).

  When the reading of the original is completed, the CPU 41e turns off the lamp 4 and ends the process (step S406).

  As described above, when the color image reading apparatus 1 of the present embodiment starts lighting, the image data read by the CCD 9a fluctuates even if reading is performed by the lamp 4 having the maximum light amount, but the image data read by the CCD 9a is changed. The reference voltage value of the A / D converter 42b for digital conversion is adjusted according to the CCD target value.

  Therefore, even when the target light quantity of the lamp 4 differs depending on the mode or the like, that is, when the target CCD output is different, the target CCD output (CCD target value) is stabilized quickly and inexpensively while suppressing overshoot. Therefore, versatility and usability can be improved without changing the lamp 4 and the inverter circuit 62, and the image quality of the read image can be improved.

  22 to 25 are views showing a fifth embodiment of the image reading apparatus and the image processing apparatus of the present invention, and FIG. 22 applies the fifth embodiment of the image reading apparatus and the image processing apparatus of the present invention. FIG. 110 is a light source control circuit diagram 110 of a color image reading apparatus.

  The present embodiment is applied to a color image reading apparatus similar to the color image reading apparatus 1 of the first embodiment. In the description of this embodiment, the same components as those of the first embodiment are described. Are given the same reference numerals, and detailed description thereof is omitted, and parts not shown in the drawings are described using the reference numerals used in the description of the first embodiment as they are, if necessary.

  In FIG. 22, a light source control circuit 110 includes a CCD 9a, an analog processing circuit 42a of a VIOB (signal processing means) 42, an A / D converter 42b, an image data comparison unit 71, and an inverter circuit 62, and a digital arithmetic circuit ( (Digital signal processing means) 111 and a digital gain calculation circuit 112, and the size of the analog image data output from the CCD 9a is adjusted by changing the digital gain. Note that the image data comparison unit 71, the digital arithmetic circuit 111, and the digital gain arithmetic circuit 112 are constructed by, for example, the CPU 41e of the SCU 41 executing a CCD output control program stored in the ROM 41f.

  As described above, the CCD 9a converts the reflected light from the original into RGB analog image data having voltage values corresponding to the light intensity, and inputs the analog image data to the analog processing circuit 42a on the VIOB 42. The analog processing circuit 42a Removes the dark potential portion, synthesizes the odd and even bits, adjusts the analog gain to the amplitude based on the analog gain setting value from the CPU 41e, and outputs it to the A / D converter 42b. The A / D converter 42b converts the analog image data whose gain has been adjusted by the analog processing circuit 42a into digital image data and outputs the digital image data to the digital arithmetic circuit 111. The digital arithmetic circuit 111 receives the digital gain setting value from the CPU 41e. The digital gain is adjusted to the amplitude based on the above and output to the subsequent image processing unit of the shading unit 42 c and also output to the image data comparison unit 71.

  The image data comparison unit 71 compares the CCD target value (target value) set in advance with the measured image data (measured image data) adjusted by the digital gain input from the digital arithmetic circuit 111, and the difference between the comparison results Is output to the digital gain calculation circuit 112.

  The digital gain calculation circuit 112 determines a digital gain value to be set in the digital calculation circuit 111 based on the difference that is a comparison result between the CCD target value and the measured image data, and outputs the digital gain value to the digital calculation circuit 111.

  That is, the digital gain calculation circuit 112 selects, in the ROM 41f, a digital gain calculation program and a digital gain change amount table, for example, a target value (target value) difference Δβ (digit) and the target value difference Δβ as shown in FIG. A digital gain change amount table corresponding to the digital gain change amount ΔG (times) to be stored is stored in advance, the target value difference Δβ is calculated by the digital gain calculation program, and the digital gain change amount ΔG corresponding to the target value difference Δβ is calculated. From the digital gain change amount table, and the digital gain G (= G + ΔG) obtained by adding the read digital gain change amount ΔG to the current digital gain G is output to the digital arithmetic circuit 111 as the changed digital gain. In FIG. 23, the target value difference Δβ between the numerical values of the target value differences Δβ in the digital gain change amount table employs a target value difference Δβ that selects the larger digital gain change amount ΔG.

  That is, the target value (CCD target value) of the value after the density reference plate is read by the CCD 9a and A / D converted is α, the analog gain is adjusted by the analog processing circuit 42 after being read by the CCD 9a, and is digitally converted by the A / D converter 42b. When the current image data (actually measured value) whose digital gain has been adjusted by the digital arithmetic circuit 111 after conversion is β, the image data comparison unit 71 calculates the target value difference Δβ = α−β to obtain the digital gain. The digital gain calculation circuit 112 obtains the digital gain change amount ΔG from the digital gain change amount table based on the target value difference Δβ.

  At this time, the image data comparison unit 71 compares the CCD target value set in advance with the image data (actual measurement value). If the CCD target value and the image data that is the actual measurement value are equal, “0” is output to the digital gain calculation circuit 112 as the target value difference Δβ with respect to the image data, and the digital gain calculation circuit 112 has a target value difference Δβ between the CCD target value and the actually measured image data of “0”. Therefore, the same digital gain G as before is output to the digital arithmetic circuit 111. The digital arithmetic circuit 111 converts the digital image data read by the CCD 9 a, analog gain adjusted by the analog processing circuit 42, and digitally converted by the A / D converter 42 b, based on the digital gain value G from the digital gain arithmetic circuit 112. The digital gain is adjusted and output to the image data comparison unit 71.

  Next, the operation of this embodiment will be described. The color image reading apparatus 1 of the present embodiment controls the image data processing of the actually measured image data based on the actually measured image data read by the CCD 9a, in particular, controls the digital gain, and sets the image data output from the CCD 9a to the target value (CCD (Target value).

  That is, in the color image reading apparatus 1, when a document is set on the document table 21 of the ARDF 20, a setting operation necessary for reading the document is performed by the SOP 51, and the start switch is turned on, the CPU 41e is shown in FIG. As described above, a clock signal CLK having a preset initial frequency is output to the inverter circuit 62, and the inverter circuit 62 is driven to turn on the lamp 4 at the initial frequency (step S501). This initial frequency is a frequency at which the lamp 4 is lit with the maximum light amount.

  The CCD 9a outputs analog image data with the amount of light from the lit lamp 4 to the analog processing circuit 42a. The analog processing circuit 42a removes the dark potential portion from the analog image data input from the CCD 9a, and the CPU 41e. After the gain is adjusted with the analog gain setting value from, the signal is output to the A / D converter 42b. The A / D converter 42b converts the analog image data whose gain has been adjusted by the analog processing circuit 42a into digital image data and outputs the digital image data to the digital arithmetic circuit 111. The digital arithmetic circuit 111 has a function constructed by the CPU 41e. The digital gain is adjusted in accordance with the digital gain value set from the digital gain calculation circuit 112, and is taken into the image data comparison unit 71 (step S502).

  This initial digital gain is a gain value that appropriately adjusts the digital gain of the reading value of the CCD 9a by the lamp 4 that is lit at the maximum light amount when lit.

  When the color image reading apparatus 1 takes in the image data whose digital gain has been adjusted by the digital arithmetic circuit 111 to the image data comparison unit 71 as the actual measurement image data, the image data comparison unit 71 compares the actual measurement image data with the CCD target value. The target value difference Δβ is calculated (step S503). If the target value difference Δβ is not “0” and the target value difference Δβ is between the actually measured image data and the CCD target value, the digital gain calculation circuit 112 is calculated. However, referring to the digital gain change amount table of the ROM 41f shown in FIG. 23, the digital gain value of the digital arithmetic circuit 111 is calculated based on the target value difference Δβ (step S504).

  That is, now, assuming that the CCD target value is α and digitally measured actual image data is β, the image data comparison unit 71 calculates the target value difference Δβ from the following equation.

Δβ = α-β
After calculating the target value difference Δβ, the image data comparison unit 71 outputs the calculated target value difference Δβ to the digital gain calculation circuit 112, and the digital gain calculation circuit 112 receives the target value input from the image data comparison unit 71. Based on the difference Δβ, the digital gain change amount table in the ROM 41f is referred to, and the digital gain set value change amount (digital gain change amount) ΔG (times) of the digital arithmetic circuit 11 is calculated. For example, if the target value difference Δβ = −26, No. in the digital gain change amount table. 2. A value corresponding to “−30” of 2, ΔG = −0.6 times is selected. In this case, if the current digital gain value G is G = 1.0 times, the calculated digital gain value G becomes G + ΔG = 0.4 times, and the digital gain value G in the digital operation circuit 111 decreases. As a result, the image data becomes smaller.

  If Δβ = 15, No. in the digital gain change amount table. A value corresponding to “10” of 6 and ΔG = + 0.2 times are selected. In this case, if the current digital gain value G is G = 1.0G, the calculated digital gain value G becomes G + ΔG = 1.2 times, and the digital gain value G of the digital arithmetic circuit 111 increases. The image data becomes large.

  The digital gain calculation circuit 112 outputs the calculated digital gain value G to the digital calculation circuit 111, and the digital calculation circuit 111 adjusts the gain of the image data with the digital gain value G.

  When the digital gain calculation circuit 112 changes the setting value of the digital gain of the digital calculation circuit 111, the color image reading apparatus 1 returns to step S502 and reads the image data by the CCD 9a again to obtain the measured image data. The actual image data obtained by adjusting the gain with a digital gain value G changed by the digital arithmetic circuit 111 after adjusting the gain with a predetermined analog gain value by the analog processing circuit 42a and digitally converting with the A / D converter 42b. The process of comparing the CCD target values is repeated in the same manner as described above (steps S502 to S504). When the actually measured image data adjusted with the digital gain matches the CCD target value in step S503, the digital gain value G of the digital arithmetic circuit 111 is obtained. Start reading operation without change Te, reads the document set on the document table 21 (step S505).

  When the reading of the document is completed, the CPU 41e turns off the lamp 4 and ends the process (step S506).

  As described above, when the color image reading apparatus 1 of the present embodiment starts lighting, the image data read by the CCD 9a fluctuates even if reading is performed by the lamp 4 having the maximum light amount, but the image data read by the CCD 9a is changed. The digital gain value of the digital arithmetic circuit 111 that performs digital gain adjustment of digital image data that has been digitally converted by analog gain adjustment is adjusted so that the actually measured image data after the digital gain adjustment becomes the CCD target value.

  Therefore, even when the target light quantity of the lamp 4 differs depending on the mode or the like, that is, when the target CCD output is different, the target CCD output (CCD target value) is stabilized quickly and inexpensively while suppressing overshoot. Therefore, versatility and usability can be improved without changing the lamp 4 and the inverter circuit 62, and the image quality of the read image can be improved.

  Then, the color image reading apparatus 1 performs the change adjustment of the digital gain value in the DUMMY pixel area other than the effective pixel area in the CCD reading 1 line at the main scanning timing of the output of the CCD 9a shown in FIG. . Further, the adjustment adjustment of the analog gain to the analog processing circuit 42a of the third embodiment and the adjustment adjustment of the reference voltage to the A / D converter 42b of the fourth embodiment may be performed in the DUMMY pixel region. .

  As described above, when the adjustment process is performed in the DUMMY pixel area, the adjustment process can be appropriately performed without affecting the document read image data.

  The invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to the above, and various modifications can be made without departing from the scope of the invention. Needless to say.

  The present invention can be applied to an image reading apparatus that turns on a light source, irradiates the original with light from the light source, and reads an image of the original and an image processing apparatus including such an image reading apparatus.

1 is a schematic front view of a color image reading apparatus to which a first embodiment of an image reading apparatus and an image processing apparatus of the present invention is applied. FIG. 2 is a block configuration diagram of the color image reading apparatus of FIG. 1. The circuit block block diagram of the principal part of FIG. FIG. 2 is a lamp power supply circuit diagram of the color image reading apparatus of FIG. 1. The detailed circuit block diagram of the inverter circuit and lighting control part of FIG. 6 is a timing chart of the control signal and the line synchronization signal in FIGS. 4 and 5. 6 is a timing chart of the control signal, line synchronization signal, clock signal, and optical waveform of FIGS. FIG. 2 is a light source control circuit diagram of the color image reading apparatus of FIG. 1. The figure which shows an example of the CLK idle period change amount table which the CLK idle period calculating part of FIG. 8 uses. 2 is a flowchart showing light amount adjustment processing by the color image reading apparatus of FIG. 1. The figure which shows the CCD output at the time of the conventional starting. The figure which shows CCD output at the time of a standup | rising at the time of performing the light quantity adjustment process of FIG. FIG. 6 is a light source control circuit diagram of a color image reading apparatus to which a second embodiment of the image reading apparatus and the image processing apparatus of the present invention is applied. 14 is a flowchart showing light amount adjustment processing by the color image reading apparatus of FIG. The figure which shows the CCD output at the time of the standup | rising at the time of performing the light quantity adjustment process of FIG. FIG. 7 is a light source control circuit diagram of a color image reading apparatus to which a third embodiment of the image reading apparatus and the image processing apparatus of the present invention is applied. The figure which shows an example of the analog gain change amount table which the analog gain calculating circuit of FIG. 16 uses. FIG. 17 is a flowchart showing an analog gain adjustment process by the color image reading apparatus of FIG. FIG. 10 is a light source control circuit diagram of a color image reading apparatus to which a fourth embodiment of the image reading apparatus and the image processing apparatus of the present invention is applied. The figure which shows an example of the reference voltage change amount table which the reference voltage calculating circuit of FIG. 19 uses. 20 is a flowchart showing reference voltage adjustment processing by the color image reading apparatus of FIG. FIG. 10 is a light source control circuit diagram of a color image reading apparatus to which a fifth embodiment of the image reading apparatus and the image processing apparatus of the present invention is applied. The figure which shows an example of the digital gain change amount table which the digital gain calculating circuit of FIG. 22 uses. 23 is a flowchart showing digital gain adjustment processing by the color image reading apparatus of FIG. FIG. 25 is a main scanning timing diagram of CCD output for explaining the processing timing of the digital gain adjustment processing of FIG. 24;

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color image reader 2 Main body housing 3 Contact glass 4 Lamp 5 1st mirror 6 2nd mirror 7 3rd mirror 8 Lens 9 CCD drive unit (SBU)
9a CCD
10 Scanner motor 11 System control unit (SCU)
12 First carriage 13 Second carriage 14 Registration sensor 20 ARDF
21 Document Plate 21a Document Guide 22 Calling Roller 23 Paper Feed Belt 24 Transport Roller 25 Separation Roller 26 First Transport Roller 27 Reflection Guide Plate 28 Second Transport Roller 29 Paper Discharge Roller 30 Reverse Roller 31 Branch Claw 32 Reverse Table 33 Original Document End Detection Sensor 34 Width Size Detection Board 35 First Document Length Sensor 36 Second Document Length Sensor 37 Set Sensor 38 DF Document Glass 39a Carrying Motor 39b Feed / Reverse Motor 41 SCU
41a IPU
41b memory controller 41c SDRAM
41d External I / F driver 41e CPU
41f ROM
41g RAM
41h NVRAM
41i Motor driver 42 VIOB
42a Analog processing circuit 42b A / D converter 42c Shading part 43 ADU
44 OIPU
45 NIC
46 ISIC
47 PSU (power supply unit)
48 Power switch 49 Plug 50 Scanner motor 51 SOP
60 Lamp power supply circuit 61 Constant voltage power supply 62 Inverter circuit 63 Lighting control circuit 64 Step-up transformer Tr1 Transistor R1, R2 Resistance D1 Diode FET1 Switching element 65 Inverter control IC
DESCRIPTION OF SYMBOLS 70 Light source control circuit 71 Image data comparison part 72 CLK idle period calculating part 80 Light source control circuit 81 CLK idle period switching part 90 Light source control circuit 91 Analog gain arithmetic circuit 100 Light source control circuit 101 Reference voltage arithmetic circuit 102 D / A converter 110 Light source Control circuit 111 Digital arithmetic circuit 112 Digital gain arithmetic circuit

Claims (11)

  A lighting pulse having a predetermined lighting pulse pause period in one image reading line is output from the control means to the driving means, and the driving means turns on the light source based on the lighting pulse to irradiate the original with the reading light, In the image reading apparatus that converts the reflected light from the original into image data by the photoelectric conversion means, the control means changes the lighting pulse pause period output to the driving means to adjust the light quantity of the light source. An image reading apparatus.   The control means provides the driving means with a lighting pulse pause period longer than a preset lighting pulse pause period at the maximum light quantity as the lighting pulse pause period when the light source rises at the maximum light quantity. The image reading apparatus according to claim 1, wherein the image reading apparatus outputs the image.   The image reading apparatus according to claim 1, wherein the control unit determines the lighting pulse pause period based on image data output from the photoelectric conversion unit and outputs the determined period to the driving unit.   3. The control unit according to claim 1, wherein the control unit determines the lighting pulse pause period in which the image data output from the photoelectric conversion unit has a predetermined target value, and outputs the determined period to the driving unit. Image reading device.   The image reading apparatus according to claim 1, wherein the control unit gradually changes the lighting pulse pause period over a plurality of stages.   In an image reading apparatus that converts reflected light of light emitted from a light source onto a document into analog image data by a photoelectric conversion unit, performs signal processing on the analog image data by a signal processing unit, and finally converts the analog image data into digital image data The image processing apparatus is characterized in that the signal processing means processes the image data output from the photoelectric conversion means to a predetermined target value at least when the light source is turned on.   The signal processing means includes analog signal processing means for amplifying analog image data from the photoelectric conversion means based on an analog gain value input from the control means, and the control means outputs the photoelectric conversion means. 7. The image reading apparatus according to claim 6, wherein the analog gain value for amplifying image data to the predetermined target value is output to the analog signal processing means.   The signal processing means includes digital conversion means for converting analog image data from the photoelectric conversion means into digital image data based on a reference voltage input from the control means, and the control means is the digital conversion means. 7. The image reading apparatus according to claim 6, wherein the reference voltage at which the converted digital image data becomes a predetermined target value is output to the digital conversion means.   The signal processing means comprises digital signal processing means for amplifying digital image data after digital conversion of analog image data from the photoelectric conversion means based on a digital gain value input from the control means, and the control means 8. The digital gain value for amplifying digital image data obtained by digitally converting analog image data from the photoelectric conversion means to the predetermined target value is output to the digital signal processing means. Image reading device.   10. The image reading apparatus according to claim 1, wherein the image reading device performs the change of the lighting pulse pause period or the signal processing by the signal processing unit in an area other than an effective image area in one line of image reading. The image reading apparatus according to any one of the above. An image processing apparatus, comprising: an image reading unit configured to irradiate a document with light from a light source and reading an image of the document; and performing various image processing on image data of the document read by the image reading unit. An image processing apparatus comprising the image reading unit according to claim 1 as a unit.

Images