JP2000224380A - Original reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an original reader where a degree of control freedom in the case of reading. SOLUTION: An RGB LED array 14 where a plurality of LEDs emitting lights with a plurality of different wavelength are arranged, emits a light onto a photo film 16. A 3-line CCD sensor 20 where a plurality of CCDs receiving lights with a plurality of different wavelength are arranged, receives a light transmitted through the photo film 16. A controller controls each CCD so that each CCD receives the light transmitted through the photo film 16 for a storage time that is an integer multiple of a minimum storage time in the unit of the predetermined minimum storage time and controls each LED so that each LED emits a light that is pulse-width-modulated synchronously with the storage time for one period of the minimum storage time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an original reading apparatus, and more particularly, to an original reading apparatus for reading an original using a light source for illuminating the original and an optical sensor for receiving light from the original.

[0002]

2. Description of the Related Art Conventionally, various devices have been proposed as devices for emitting a plurality of different color lights from a plurality of LEDs to illuminate a document and receiving reflected light from the document as light having a plurality of different wavelengths by a CCD sensor. ing. For example, there has been proposed an apparatus that illuminates an object by sequentially emitting a plurality of different color lights and reads reflected light from the object in synchronization with the emission of each color light (JP-A-10-32681). Also, L
The bar code is illuminated with light emitted from each LED of the ED array, the reflected light from the bar code is read by a CCD line sensor, and the bar code is illuminated with a uniform and constant light amount based on the amount of light received by each CCD. As described above, an apparatus for setting the duty of the light emission time of each LED corresponding to each CCD has been proposed (JP-A-7-6197).

[0003]

By the way, in the above-mentioned apparatus, the accumulation time (light receiving time) of the CCD sensor is changed by constantly emitting light from a plurality of LEDs so that the CCD sensor has a desired light receiving amount. The light emission time of a plurality of LEDs is controlled by fixing the accumulation time of the CCD.

As described above, if only one of the accumulation time of the CCD sensor and the light emission time of the plurality of LEDs is controlled, not only the degree of freedom of control is narrow, but also fine control cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has as its object to provide a document reading apparatus in which the degree of control in reading is improved.

[0006]

According to the first aspect of the present invention, there is provided a light source for illuminating a manuscript constituted by arranging a plurality of light emitting elements each of which emits light of a plurality of different wavelengths. An optical sensor configured to arrange a plurality of light receiving elements that receive light from a light source and configured to receive light from an original; and the optical sensor is configured to have a predetermined minimum storage time as a unit and to be an integral multiple of the minimum storage time. During the light reception time of
Control means for controlling to receive light from the original, and controlling each of the light emitting elements to emit light in pulse width modulation in synchronization with a light receiving available time and with a minimum accumulation time as one cycle. I have. Here, the light from the original includes both light transmitted through the original and light reflected by the original.

A light source according to the present invention illuminates a document by arranging a plurality of light emitting elements each emitting light of a plurality of different wavelengths. The optical sensor arranges a plurality of light receiving elements for receiving light, and receives light from a document.

[0008] The control means controls the optical sensor to receive light from the document during a receivable time that is an integral multiple of the minimum accumulation time in units of a predetermined minimum accumulation time. Each light-emitting element is controlled so as to emit light by pulse width modulation in synchronization with the light-receiving time and with the minimum accumulation time as one cycle.

As described above, the optical sensor receives light from a document for a light receiving time that is an integral multiple of the minimum storage time in units of a predetermined minimum storage time, and each light emitting element receives light from the original. Since light emission is performed by pulse width modulation in synchronization with the possible time and with the minimum accumulation time as one cycle, it is possible to improve the degree of freedom of control at the time of reading and to perform fine control.

[0010] By the way, the control means sets a state in which the plurality of optical sensors for receiving light of a plurality of different wavelengths read the transmitted light from the original without the original, and read the reflected light from the original. , Based on the outputs from the plurality of optical sensors when a reference plate of a predetermined color is arranged in place of the original,
Calculate the target value of at least one of the receivable time of each of the plurality of light sensors and the light emission pulse width of each of the light emitting elements so that the color balance and the light distribution of each light emitting element fall within the allowable range. Control may be performed so that

As described above, the target value of at least one of the light receiving time of each of the plurality of optical sensors and the light emission pulse width of each of the light emitting elements for calculating the color balance and the light distribution of the light emitting elements within the permissible range is calculated. Is controlled so as to become the calculated target value, so that the document can be illuminated with light having a color balance and light distribution within an allowable range.

The control means may control the receivable time and the light emitting pulse width of each light emitting element so that the light receiving amount of light from the document by the plurality of optical sensors becomes a desired light receiving amount. .

As described above, the drive current to the light emitting element, the light receiving time of each of the plurality of light sensors, and the light emission pulse width of each light emitting element so that the color balance and the light distribution of each light emitting element fall within the allowable range. Since at least one of the target values is calculated and controlled so as to become the calculated target value, finer control can be performed while further improving the degree of freedom of control in reading.

The control means includes a light-receiving available time, a light-emitting pulse width of each light-emitting element, and a drive to the light-emitting element such that the light-receiving amount of light from the original of each of the plurality of optical sensors becomes a desired light-receiving amount. The current may be controlled.

The light source includes a light emitting element arranged on a substrate, and further includes a detecting means for detecting the temperature of the substrate, and a temperature changing means for changing the temperature of the substrate. The temperature change means may be controlled so that the temperature of the substrate becomes the reference temperature based on the temperature detected by the method.

As described above, since the temperature of the substrate is set to the reference temperature based on the detected temperature of the substrate, the LEDs can be maintained at the reference temperature. Can be emitted with the same amount of light.

Further, according to the present invention, a light source for illuminating a document, which is constituted by arranging a plurality of light emitting elements for emitting light, an optical sensor for receiving light from the document, and each of the light emitting elements The blinking period of the light sensor becomes an integral multiple of a predetermined minimum accumulation time, and the light receivable time of the optical sensor is equal to or longer than the minimum accumulation time and the light can be received for an integer number of times of light emission of the light emitting element. Thus, a configuration may be provided that includes control means for controlling the light-receivable time and the blinking cycle. According to the present invention, both the light-receiving time of the optical sensor and the cycle and the light-emission pulse width of the light-emitting element are controlled. Compared to the case where only at least one of the widths is controlled, the degree of freedom of control for receiving a predetermined light amount is improved, and finer control can be performed. Note that the light receiving available time refers to a time during which the optical sensor is ready to receive light, and for example, a time during which an electronic shutter disposed between each light emitting element and the optical sensor is opened, that is, a charge accumulable time. Means In addition, the minimum accumulation time is a minimum time capable of controlling the light receiving available time, for example, a minimum time capable of controlling the opening of the electronic shutter.

According to a ninth aspect of the present invention, the control means calculates a target value of at least one of a light receiving time of the optical sensor and a light emission pulse width of each of the light emitting elements. It is also possible to control the light receiving available time and the blinking cycle so that

Further, according to the present invention, the control means can be configured to be capable of controlling a drive current to the light emitting element.

Further, in the present invention, a light emitting diode (LED) can be used as the light emitting element.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the image reading apparatus according to the present embodiment includes a plurality of LED groups each of which emits light in a different wavelength band, which illuminates a photographic film 16 by being driven by an LED driving circuit 12. In this embodiment, R light, G light
RGB with three LED groups that emit light and B light
A D array 14 is provided. Three LED groups that emit R light, G light, and B light are arranged in a row. Note that a temperature sensor and a heater (not shown) are arranged on the substrate of the RGB LED array 14 on which the LEDs are arranged.

A lens 18 for imaging transmitted light of the photographic film 16 along the optical axis C of the RGBLED array 14 in the order closer to the RGBLED array 14, and light in different wavelength ranges (images formed by the lens 18). A plurality of line light sensors that receive transmitted light), in the present embodiment, R
A three-line CCD sensor 20 having three CCD lines for receiving light, G light, and B light is arranged. Three C
The line direction of the CD line corresponds to the column direction of three LED groups that emit R light, G light, and B light in the RGB LED array 14. The three-line CCD sensor 20
Has an electronic shutter function for each line. An analog circuit 22 is connected to the three-line CCD sensor 20 corresponding to each of the three lines.
An analog / digital (A / D) converter 24 is connected to 2.

As shown in FIG. 2, the control system of the image reading apparatus according to the present embodiment includes a controller 26. The temperature sensor 30 and the heater 32 described above are connected to the controller 26. Controller 2
6 includes the LED drive circuit 12 and the A / D converter 2 described above.
CC for driving 4 and 3 line CCD sensor 20
The D driver 28 is connected.

As shown in FIG. 3, the LED driving circuit 12
A crystal oscillator 34, a counter 36 that counts signals from the crystal oscillator 34, outputs a signal corresponding to the count value, resets when the count reaches the upper limit value, and starts counting again, and a plurality of LEDs provided corresponding to each LED. The PWM modulation circuit 38 of FIG. Since each PWM modulation circuit 38 has the same configuration, only one PWM modulation circuit 38 will be described, and the other description will be omitted. The PWM modulation circuit 38 is set to a predetermined value by the controller 26 (see FIG. 2), a register 40 for outputting a signal corresponding to the set predetermined value, and a signal corresponding to the count value from the counter 36 being input. A first input terminal that is not provided and a second input terminal (not shown) to which a signal corresponding to a predetermined value from the register 40 is input, and is represented by a signal input to the first input terminal and the second input terminal. And a comparator 4 that outputs a signal when the value represented by the signal input to the first input terminal is smaller than the value represented by the signal input to the second input terminal.
2, a collector connected to the LED 56 via a resistor, and a transistor 52 connected to the output terminal of the comparator 42 via a resistor 48 and a capacitor 50, a buffer 46, and a D-FF 44 connected in parallel to the base.
It has.

Next, the operation of the present embodiment will be described. The photographic film 16 is made up of three CCs by a conveying means (not shown).
While being transported in a direction orthogonal to the direction of the D line,
The ED drive circuit 12 performs pulse width modulation (PWM) on each LED as described later. The light emitted from each LED illuminates the photographic film 16. The transmitted light transmitted through the photographic film 16 is transmitted by a lens 18 to a three-line CCD.
An image is formed on the sensor 20. That is, the image of the image frame recorded on the photographic film 16 is read while the photographic film 16 is being conveyed. In this embodiment, an image of an image frame recorded on the photographic film 16 is preliminarily read (pre-scanned) while the photographic film 16 is reciprocally conveyed, and each image frame obtained by the pre-scan is read. A reading condition such as an accumulation time (light receiving time) is calculated based on the density of the image, and the image of each image frame is fully read (fine scan) according to the calculated reading condition.

Here, in the present embodiment, three lines CC
Since the accumulation time of the D sensor 20 and the light emission time of each LED are pulse width modulated, the amount of light received during the accumulation time determined in the 3-line CCD sensor 20 according to the density of the image frame varies for each reading cycle. It is necessary to prevent flickering and the like. Further, it is necessary to adjust the color balance and light distribution of each LED. Furthermore, since the wavelength and the amount of color light emitted from each LED fluctuate according to the temperature, it is necessary to prevent this. In the present embodiment, in consideration of the above fact, control is performed as follows.

That is, the three-line CCD sensor 20
The light transmitted through the photographic film 16 is stored in an integral multiple of the minimum storage time T (see FIG. 4), which is determined from the time during which the CD can be driven and the time during which the LED can emit light. The electronic shutter is controlled for each line so as to receive light. Note that the minimum accumulation time T is determined as follows. First, the range of exposure control is determined, and the amount of received light in one step is determined. Next, the open time of the CCD electronic shutter is set to a value that does not affect the response of the CCD electronic shutter, and the blinking cycle and the light emission pulse width of the LED are determined so that the amount of light received in one step can be received by the CCD. Check if the LED blinking cycle and emission pulse width are reasonable.
The opening time of the D electronic shutter is defined as the minimum accumulation time T.
If it is impossible, the range of the exposure control is lowered, and the minimum accumulation time T is determined by the above procedure.

In this embodiment, one cycle of the electronic shutter is an integral multiple of the minimum accumulation time T, as shown in FIG.

On the other hand, the LED drive circuit 12
Is synchronized with the minimum accumulation time T and the minimum accumulation time T is set to 1
Performs pulse width modulation with a period. That is, the counter 36
The CCD drive signal is input and reset, and the pulse count corresponding to the minimum accumulation time T, for example, 100 pulses (upper limit) is counted and reset. On the other hand, the controller 26 controls the light emission time t within each minimum accumulation time so that the desired light reception amount is obtained in the accumulation time determined based on the density of the image frame to be read next.
(See FIG. 4), and a value corresponding to the calculated light emission time, for example, 50 is set in a register. The controller 26 outputs the CCD drive signal to the CCD driver 28 and the counter 36 of the LED drive circuit 12 as shown in FIG. The counter 36 that has received the CCD drive signal resets and starts counting pulse signals from the crystal oscillator, and outputs a signal corresponding to the count value to the comparator 42 as described above. on the other hand,
The register 40 outputs a signal corresponding to a value (for example, 50) corresponding to the light emission time t to the comparator 42 by the controller 26. The comparator 42 outputs a signal corresponding to the count value and a value corresponding to the light emission time t (for example, 5
The signal corresponding to 0) is compared with the signal, and a signal is output when the count value is smaller than the value corresponding to the light emission time t. This signal is input to the base side of the transistor 52 via the D-FF 44, the buffer 46, the resistor 48, and the capacitor 50. Therefore, while the count value of the counter 36 is smaller than the value corresponding to the light emission time t, the transistor 5
2 is turned on, and a drive current flows through the LED to emit light. When the count value of the counter 36 becomes equal to or longer than the value corresponding to the light emission time t, the transistor 52 is turned off and the LED is turned off.
As described above, is configured to count and reset to the number of pulses corresponding to the minimum accumulation time T, for example, 100 pulses. Therefore, when counting to 100, the LED emits light again. As described above, the LED drive circuit 12 performs pulse width modulation on each LED in synchronization with the minimum accumulation time T and using the minimum accumulation time T as one cycle.

Then, the CCD driver 28 is arranged as shown in FIG.
As shown in (B), when it is time to leave the accumulation time (an integral multiple of the minimum accumulation time) within one cycle from the input of the CCD drive signal, the next CCD drive signal is input. Until the operation is completed, that is, during the storage time. When the electronic shutter is opened, each LED is pulse-width modulated by the LED drive circuit 12 as described above, and emits light so as to have a desired light receiving amount.

As described above, the three-line CCD sensor 20
Using the minimum storage time as a unit, the electronic shutter is controlled so as to receive the transmitted light of the photographic film 16 with an integration time that is an integral multiple of the minimum storage time, and the LED drive circuit 12 synchronizes each LED with the minimum storage time. And the minimum accumulation time T
Is subjected to one cycle of pulse width modulation, so that the amount of light received by the three-line CCD sensor 20 can be freely and optimally controlled.

That is, it is possible to prevent flicker or the like in which the amount of received light during the fixed accumulation time of the three-line CCD sensor 20 fluctuates in each reading cycle.

Further, as described above, the light receiving amount of each line of the 3-line CCD sensor 20 can be freely and optimally controlled by the accumulation time of the 3-line CCD sensor 20 and the pulse width modulation of each LED of the LED drive circuit 12. So you can
A diaphragm plate, a color balance filter, and the like can be omitted, and the configuration can be simplified.

It should be noted that the three-line CCD sensor 2 has a desired light receiving amount determined based on the density of the image frame.
The accumulation time of 0 or the pulse width of each LED of the LED drive circuit 12 may be modulated.

In the present embodiment, the minimum accumulation time T
The electronic shutter is controlled so as to receive the transmitted light of the photographic film 16 for an integral time of the minimum accumulation time T in integral units of the minimum accumulation time T. However, as shown in FIG. The LED may be lighted for an integral number of times, and the CCD electronic shutter may be opened while the LED is turned off, simultaneously with turning off the LED, or simultaneously with turning on the LED. In the case of the control shown in FIG. 9, the CCD electronic shutter is opened for a time that can receive the light for the twice lighting of the LED and the transmitted light from the original is received.
In order to receive the light amount for the twice lighting, it is necessary to use P to Q in FIG.
During this time, the CCD electronic shutter opening operation may be completed.

Further, in this embodiment, as shown in FIG. 4B, one cycle of the CCD drive signal for driving the electronic shutter is set to an integral multiple of the minimum accumulation time T, but one cycle of the CCD drive signal is used. Any period can be set as one cycle as long as the period is equal to or longer than the minimum accumulation time T. For example, in the example shown in FIG. 10, one cycle of the CCD drive signal is set to 9.5T.

Further, in this embodiment, as shown in FIG. 4C, one cycle of the LED drive signal is set to the minimum accumulation time T.
However, the time obtained by multiplying one cycle of the LED drive signal by an integer becomes the minimum accumulation time, that is, the minimum accumulation time T
The pulse width modulation can also be performed with one cycle of the integral time as one cycle. For example, as shown in FIG. 10, one cycle of the LED drive signal is set to a half of the minimum accumulation time T, and the CCD is operated for a time capable of receiving light for three times of LED lighting.
The electronic shutter can be opened to receive the transmitted light from the document.

In this embodiment, R light, G light, B light
Although a three-line CCD sensor having three CCD line sensors for receiving each light is used, the present invention is not limited to this, and a color area CCD sensor may be used.

Further, a monochrome CCD sensor can be used. In this case, light of different wavelengths is read as follows. As a first method, the RGB LED array 14 is turned on in order of R light, G light, and B light to irradiate the photographic film, and during this time, the photographic film is stopped, and each color light is output from the photographic film. The transmitted light is read by a monochrome CCD sensor. As a second method, the photographic film 16 and the transmitted light from the photographic film are separated into R light, G light, and B light using a spectroscope such as a dichroic prism, and each light is separated into a plurality of different monochrome CCD sensors. Read with.

Incidentally, the RGB LED array 14
Since the three LED groups that emit light, G light, and B light are arranged in a line, the color balance and light distribution of the emitted R light, G light, and B light may be poor. Therefore, in the present embodiment, the color balance and the light distribution are adjusted in advance with no transparent original. That is, in a state where there is no transparent original, that is, in a state where the photographic film 16 is not loaded, in step 72 of FIG. 5, each LED is caused to emit light with an initial drive current and an initial pulse width. The light emitted from each LED is 3
The light is received by the line CCD sensor 20 and the analog circuit 2
2. Input to the controller 26 via the A / D converter 24. In step 74, each CCD without a transparent original
In step 76, the target value of the pulse width of each LED for calculating the color balance and the light distribution within an allowable range is calculated based on the received light reception data.
Set in register 40.

As described above, the target value of the pulse width of each LED for setting the color balance and the light distribution within the allowable range is calculated and set. Can be illuminated.

Each LED emits R light, G light, and B light. In order for the wavelength of each color light to be a desired wavelength, the temperature of the substrate on which the LEDs are mounted is the reference temperature. There is a need. That is, if the temperature of the substrate on which the LED is mounted fluctuates from the reference temperature, the wavelength of the emitted color light will deviate from the wavelength when the substrate is at the reference temperature, and the photoelectric conversion efficiency, that is, the amount of light emission will also deviate. is there.
Therefore, in the present embodiment, the adjustment process of the LED substrate temperature shown in FIG. 6 is executed at predetermined time intervals. That is, in step 78, the temperature of the substrate on which the LED is detected, which is detected by the temperature sensor 30, is acquired, and in step 80, the temperature of the substrate on which the LED is attached becomes the reference temperature based on the acquired temperature. The heater 32 is controlled. In this embodiment, the reference temperature is RGBLED
The temperature is set so that the substrate does not reach even when the array 14 is operated normally. Therefore, in the present embodiment, the substrate is heated by the heater so that the temperature of the substrate becomes the reference temperature.
Note that the reference temperature may be a temperature at which the substrate reaches when the RGB LED array 14 is normally operated. In this case, a device having a function of cooling and heating may be attached to control the temperature of the substrate to the reference temperature.

Next, a second embodiment of the present invention will be described. This embodiment has substantially the same configuration as that of the above-described first embodiment. Therefore, only different portions will be described, and description of the same portions will be omitted.

That is, as shown in FIG. 7, the PWM modulation circuit 38A according to the present embodiment includes a transistor 6 having a base connected to the D-FF 44 via an inverter 58.
2 is provided. The collector of the transistor 62 is connected to the power supply of the LED 56 via the resistor 60. The emitter side of the transistor 62 is connected to the emitter side of the transistor 52. That is, the driving transistor of the LED is of a differential type. That is, when one is on, the other is off. Transistor 62
The transistor 64 connected to the collector side is connected to the emitter side of the transistor 52. The base side of the transistor 64 is connected to the output terminal of the operational amplifier 66. The negative input terminal of the operational amplifier 66
The emitter side of the transistor 64 is connected, and the plus input terminal is connected to the controller 26. That is, the potential on the emitter side of the transistor 64 is
Is controlled to have the potential set by

In the above-described embodiment, the accumulation time of the three-line CCD sensor and the pulse width of each LED are adjusted so that the amount of light received by each CCD becomes a desired amount of light received.
The present invention is not limited to this, and in the second embodiment, 3
Accumulation time of line CCD sensor, pulse width of each LED,
And the drive current is adjusted. As a result, as shown in FIG. 8, the amount of light received by the CCD is increased or decreased so as to be a desired amount of received light. In addition, 3 line CC
At least one of the accumulation time of the D sensor, the pulse width of each LED, and the drive current may be adjusted.

That is, based on the density of the image frame, the controller 26 calculates the accumulation time of the three-line CCD sensor, the pulse width of each LED, and the value of the drive current so that the light receiving amount of each CCD becomes a desired light receiving amount. Is calculated, and control is performed so that the calculated value is obtained. That is, the potential at which the drive current becomes the calculated value is set in the operational amplifier 66.

When adjusting the color balance and the light distribution, the color balance and the light distribution should be within the allowable range.
The accumulation time of the three-line CCD sensor, the pulse width of each LED, and the value of the drive current may be calculated and controlled to be the calculated values. In the present embodiment, FIG.
May be performed.

The first embodiment and the second embodiment
In the above embodiment, the case where a CCD element is used as an optical sensor has been described as an example. However, the present invention is not limited to this, and another solid-state imaging device such as a MOS type imaging sensor can be used.

Further, while the above description has been made taking a negative film as an example, the present invention is not limited to this, and the original according to the present invention may be a transparent original other than a film image recorded on a photographic film. Often, the invention is applicable, for example, to a film reader for a telecine converter. Also,
It may be a reflection original such as an image recorded on a medium having low light transmittance or having no light transmittance (for example, plain paper). When adjusting the color balance or the light distribution in this case, for example, the reflected light from the white reference plate may be read and controlled as described above.

[0051]

As described above, according to the present invention, the blinking period of each light emitting element is an integral multiple of a predetermined minimum accumulation time, and the light receiving time of the optical sensor is longer than the minimum accumulation time; Since both the receivable time, the blinking cycle, and the light emission pulse width are controlled so that the light for the integer number of times of light emission of the light emitting element can be received, the degree of freedom of control at the time of reading can be improved. This also has the effect that fine control can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an image reading apparatus according to a first embodiment.

FIG. 2 is a block diagram of the image reading apparatus according to the first embodiment.

FIG. 3 is a circuit diagram of an LED drive circuit.

FIG. 4 is a timing chart of the image reading apparatus according to the first embodiment.

FIG. 5 is a flowchart illustrating a routine of a process for adjusting a color balance and a light distribution of each LED performed in a state where there is no transparent original.

FIG. 6 is a flowchart illustrating a routine of a process for adjusting the temperature of the LED substrate.

FIG. 7 is a circuit diagram of an LED drive circuit in an image reading device according to a second embodiment.

FIG. 8 is a conceptual diagram showing an output of a CCD when adjusting a color balance and a light distribution of each LED, which is performed in the absence of a transparent original in the second embodiment.

FIG. 9 is a timing chart of an image reading apparatus according to a modification.

FIG. 10 is a timing chart of an image reading apparatus according to a modification.

[Explanation of symbols]

 14 RGB LED array (light source) 20 3-line CCD sensor (plural light sensors) 26 Controller (control means) 12 LED drive circuit (control means) 28 CCD driver (control means) 30 Temperature sensor (detection means) 32 Heater (temperature change) means)

Claims (11)

[Claims] 1. A light source for illuminating a document, which is configured by arranging a plurality of light emitting elements each emitting light of a plurality of different wavelengths, and a plurality of light receiving elements for receiving light from the light source. An optical sensor that receives light from a document, and the optical sensor is based on a predetermined minimum accumulation time,
Pulse width modulation is performed so that light from the original is received during the light receiving available time which is an integral multiple of the minimum storage time, and each of the light emitting elements is synchronized with the light receiving available time and the minimum storage time is one cycle. And a control means for controlling the light emission in the document reading apparatus. 2. A control device comprising: a plurality of light sensors each including a plurality of light receiving elements for receiving light having a plurality of different wavelengths; wherein the plurality of light sensors read transmitted light from a document; In this case, when there is no original, and when reading reflected light from the original, the color of each light emitting element is determined based on the output from a plurality of optical sensors when a reference plate of a predetermined color is arranged in place of the original. The target value of at least one of the light receiving time of each of the plurality of light sensors and the light emission pulse width of each of the light emitting elements for the balance and the light distribution to be within an allowable range is calculated, and the calculated target value is obtained. 2. The document reading device according to claim 1, wherein the reading is performed. 3. The apparatus according to claim 1, wherein said control means is configured to control a drive current to said light emitting element.
Document reading device according to the above. 4. A control device comprising: a plurality of light sensors configured by arranging a plurality of light receiving elements for receiving light of a plurality of different wavelengths, wherein the plurality of light sensors read transmitted light from a document. In this case, when there is no original, and when reading reflected light from the original, the color of each light emitting element is determined based on the output from a plurality of optical sensors when a reference plate of a predetermined color is arranged in place of the original. Driving current to the light emitting element for balance and light distribution to be within an allowable range, light receiving time of the plurality of optical sensors, and at least one target value of the light emitting pulse width of each of the light emitting elements, 4. The control according to claim 3, wherein the calculated target value is controlled.
Document reading device according to the above. 5. The controller according to claim 1, wherein the light receiving time and the light emitting pulse width of each of the light emitting elements are adjusted such that the light receiving amount of the light from the document of each of the plurality of optical sensors becomes a desired light receiving amount. 3. The document reading device according to claim 1, wherein the document reading device controls the document reading device. 6. The control means includes: a light-receiving time of each of the plurality of light sensors; a light-emitting pulse width of each of the light-emitting elements; 5. The document reading apparatus according to claim 3, wherein a driving current to the light emitting element is controlled. 7. The control device according to claim 1, wherein the light source is configured by arranging the light emitting element on a substrate, further comprising: a detecting unit configured to detect a temperature of the substrate; and a temperature changing unit configured to change a temperature of the substrate. 7. The apparatus according to claim 1, wherein the control unit controls the temperature change unit based on the temperature detected by the detection unit so that the temperature of the substrate becomes a reference temperature. The document reading device according to 1. 8. A light source for illuminating a document constituted by arranging a plurality of light emitting elements for emitting light, a light sensor for receiving light from the document, and a minimum accumulation in which a blinking cycle of each of the light emitting elements is predetermined. The light-receiving time and the light-receiving time of the light sensor are set so that the light-receiving time of the light sensor is equal to or longer than the minimum accumulation time and the light can be received for an integer number of times of lighting of the light-emitting element. A document reading device comprising: a control unit configured to control a blink cycle. 9. The control means calculates a target value of at least one of a light-receiving time of the optical sensor and a light-emitting pulse width of each of the light-emitting elements, and calculates the light-receiving time so that the calculated target value is obtained. 9. The document reading apparatus according to claim 8, wherein a flicker cycle is controlled. 10. The document reading apparatus according to claim 8, wherein said control means is configured to control a drive current to said light emitting element. 11. The light emitting device according to claim 1, wherein said light emitting element is a light emitting diode.
The document reading device according to the item.